Magill, Richard (Broomfield, CO, US)
Van Doren, John C. (Bailey, CO, US)
Sellers, Bruce (Golden, CO, US)
Erickson, Tim (Littleton, CO, US)
Schnieder, Scott (Aurora, CO, US)
Courington, Steve (Lone Tree, CO, US)
Bethel, Lance (Westminister, CO, US)

Plaque It!

11/694701

10/07/2008

03/30/2007

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Signature Control Systems, Inc. (Denver, CO, US)

700/108

700/30, 264/40.1, 700/198, 700/204

B29C39/00; B29C45/76; G05B13/02; G06F19/00

700/52, 700/197-199, 425/135, 702/53, 700/175, 700/30, 264/408, 264/494-496, 425/136, 700/31, 700/174, 702/179, 702/81-84, 700/47, 700/205, 264/40.1, 264/406, 702/176, 700/108-110, 700/204, 700/51, 702/52

2765219	Apparatus for measuring and controlling alkalinity of non-aqueous liquids	October, 1956	Shawhan
3593128	MOISTURE-CONTENT-MEASURING SYSTEM EMPLOYING A SEPARATE BRIDGE CIRCUIT FOR EACH SENSING ELECTRODE THEREOF	July, 1971	Perry
3600676	MOISTURE METER UTILIZING AMPLITUDE AND BANDWIDTH SIGNALS	August, 1971	Lugwig et al.
3746975	MEASURING CHARACTERISTICS OF MATERIALS BY USING SUSCEPTIVE AND CONDUCTIVE COMPONENTS OF ADMITTANCE	July, 1973	Maltby
3753092	LIQUID TESTING DEVICE FOR MEASURING CHANGES IN DIELECTRIC PROPERTIES	August, 1973	Ludlow et al.
3778705	SUSCEPTANCE MEASURING SYSTEM FOR INDICATING CONDITION OF A MATERIAL	December, 1973	Maltby
3781672	CONTINUOUS CONDITION MEASURING SYSTEM	December, 1973	Maltby et al.
3807055	METHOD AND APPARATUS FOR MEASURING THE MOISTURE CONTENT OF WOOD	April, 1974	Kraxberger
3879644	Probe responsive to conditions of material	April, 1975	Maltby
3985712	Method and apparatus for preparing intermediate polyester resin	October, 1976	Garst
4107599	Electrode for an impedance measuring apparatus	August, 1978	Preikschat
4261525	Moisture measuring apparatus	April, 1981	Wagner
4331516	Curing of tetrabasic lead pasted battery electrodes	May, 1982	Meighan
4338163	Curing of tetrabasic lead pasted battery electrodes	July, 1982	Rittenhouse
4344142	Direct digital control of rubber molding presses	August, 1982	Diehr, II et al.
4373092	Method of process control for thermosetting resins having addition-type reactions	February, 1983	Zsolnay
4377783	Moisture detector	March, 1983	Wagner
4381250	Curing of tetrabasic lead pasted battery electrodes	April, 1983	Rittenhouse
4389578	Controlled gate circuit	June, 1983	Wagner
4399100	Automatic process control system and method for curing polymeric materials	August, 1983	Zsolnay et al.
4423371	Methods and apparatus for microdielectrometry	December, 1983	Senturia et al.
4433286	Identification of materials using their complex dielectric response	February, 1984	Capots
4448943	Method for measuring polymerization process variables	May, 1984	Golba, Jr. et al.
4496697	Automatic process control system for curing polymeric material	January, 1985	Zsolnay et al.
4510103	Method of molding a composite body involving a thermosetting resin	April, 1985	Yamaguchi et al.
4510436	Dielectric measuring systems	April, 1985	Raymond
4515545	Control system for processing composite material	May, 1985	Hinrichs et al.
4546438	Rheometer and process of curing and testing rubber	October, 1985	Prewitt et al.
4551103	Farm products agricultural game	November, 1985	Vitale
4551807	Cure-control method for thermosetting polymeric material	November, 1985	Hsich et al.
4580233	Method of measuring moisture content of dielectric materials	April, 1986	Parker et al.
4588943	Instrument for measuring the moisture content of dielectric objects	May, 1986	Hirth
4616425	Moisture measurement apparatus and method	October, 1986	Burns
4676101	Capacitance-type material level indicator	June, 1987	Baughman
4683418	Moisture measuring method and apparatus	July, 1987	Wagner et al.
4710550	Method of using a dielectric probe to monitor the characteristics of a medium	December, 1987	Kranbuehl
4723908	Dielectric probe; method and apparatus including its use	February, 1988	Kranbuehl
4773021	Adaptive model-based pressure control and method of resin cure	September, 1988	Harris et al.
4777431	Apparatus for monitoring dielectric changes in polymeric materials	October, 1988	Day et al.
4868769	Method and an apparatus for determination of basic values	September, 1989	Persson
4881025	Frequency dependent identification of materials	November, 1989	Gregory
4896098	Turbulent shear force microsensor	January, 1990	Haritonidis et al.
5008307	Liquid silicone rubber composition capable of yielding a thermal conductive vulcanized product	April, 1991	Inomata
5032525	Qualitative process automation for autoclave cure of composite parts	July, 1991	Lee et al.
5184077	Abrasion-resistant, high pressure dielectric sensors	February, 1993	Day et al.
5201956	Cellular tumble coater	April, 1993	Humphrey et al.
5207956	Computer-controlled method for composite curing	May, 1993	Kline et al.
5208544	Noninvasive dielectric sensor and technique for measuring polymer properties	May, 1993	McBrearty et al.
5210499	In-situ sensor method and device	May, 1993	Walsh
5219498	Process for controlling curing and thermoforming of resins and composites	June, 1993	Keller et al.
5223796	Apparatus and methods for measuring the dielectric and geometric properties of materials	June, 1993	Waldman et al.
5283731	Computer-based classified ad system and method	February, 1994	Lalonde et al.
5317252	Dosimeter for monitoring the condition of polymeric materials and chemical fluids	May, 1994	Kranbuehl
5432435	Detection of cross-linking in pre-cure stage polymeric materials by measuring their impedance	July, 1995	Strong et al.
5453689	Magnetometer having periodic winding structure and material property estimator	September, 1995	Goldfine et al.
5459406	Guarded capacitance probes for measuring particle concentration and flow	October, 1995	Louge
5486319	Tire cure control system and method	January, 1996	Stone et al.
5521515	Frequency scanning capaciflector for capacitively determining the material properties	May, 1996	Campbell
5528155	Sensor for measuring material properties	June, 1996	King et al.
5569591	Analytical or monitoring apparatus and method	October, 1996	Kell et al.
5654643	Dielectric sensor apparatus	August, 1997	Bechtel et al.
5680315	System for optimizing cure and assuring quality of reversion susceptible rubber articles	October, 1997	Rimondi et al.	700/198
5749986	Control of batching and curing processes	May, 1998	Wyatt
5872447	Method and apparatus for in-situ measurement of polymer cure status	February, 1999	Hager, III
5874832	Precise high resolution non-contact method to measure dielectric homogeneity	February, 1999	Gabelich
5898309	Method for determining specific material characteristics	April, 1999	Becker et al.
5961913	Device and process for vulcanizing tires	October, 1999	Haase
5996006	Internet-audiotext electronic advertising system with enhanced matching and notification	November, 1999	Speicher
6043308	Conductive rubber composition and process for the production thereof	March, 2000	Tanahashi et al.
6114863	Method for determining the presence of water in materials	September, 2000	Krahn et al.
6124584	Moisture measurement control of wood in radio frequency dielectric processes	September, 2000	Blaker et al.
6229318	Electrical resistance type humidity sensor	May, 2001	Suda
6281801	System and method for monitoring water content or other dielectric influences in a medium	August, 2001	Cherry et al.
6323659	Material for improved sensitivity of stray field electrodes	November, 2001	Krahn
6472885	Method and apparatus for measuring and characterizing the frequency dependent electrical properties of dielectric materials	October, 2002	Green et al.
6490501	Cure monitoring and control system	December, 2002	Saunders
6703847	Determining the dielectric properties of wood	March, 2004	Venter et al.
6708555	Dielectric wood moisture meter	March, 2004	Lyons, Jr. et al.
6747461	Apparatus and method for monitoring drying of an agricultural porous medium such as grain or seed	June, 2004	Corak et al.
6784671	Moisture and density detector (MDD)	August, 2004	Steele et al.
6784672	Through-log density detector	August, 2004	Steele et al.
6797660	Silicon nitride wear resistant member and manufacturing method thereof	September, 2004	Komatsu
6989678	Determining the dielectric properties of wood	January, 2006	Venter et al.
7068050	Moisture and density detector (MDD)	June, 2006	Steele et al.
7068051	Permittivity monitor uses ultra wide band transmission	June, 2006	Anderson
7146747	Timber drying kiln	December, 2006	Studd et al.

EP0313435	April, 1989			Process and device for characterizing a sample of a crosslinked plastic material by its gel fraction during its continuous manufacture
EP0540103	May, 1993			Peroxide vulcanized rubber composition
EP0733456	September, 1996			System for optimizing cure and assuring quality of reversion susceptible rubber articles
EP0743153	November, 1996			VULCANIZATION METHOD AND APPARATUS
EP0815458	January, 1998			DETERMINING THE DIELECTRIC PROPERTIES OF WOOD
EP1050888	November, 2000			CONDUCTIVE PASTE, CONDUCTIVE STRUCTURE USING THE SAME, ELECTRONIC PART, MODULE, CIRCUIT BOARD, METHOD FOR ELECTRICAL CONNECTION, METHOD FOR MANUFACTURING CIRCUIT BOARD, AND METHOD FOR MANUFACTURING CERAMIC ELECTRONIC PART
FR2645275	October, 1990
JP58103361S	July, 1983
JP62110743S	May, 1987			CONTROL METHOD FOR EQUIVALENT REACTION AMOUNT
JP03502728H	June, 1991
JP07198642H	August, 1995			VULCANIZATION CHARACTERISTIC TESTER INCORPORATING FUNCTION FOR MEASURING ELECTRICAL RESISTANCE OF RUBBER COMPOSITE
JP08285802H	November, 1996			MEASURING METHOD OF PROGRESS STATE OF CROSS-LINKING REACTION OF RUBBER BY ELECTRICAL CHARACTERISTIC VALUE
JP08323775	December, 1996			METHOD FOR FORMING DATA BASE OF VULCANIZATION CONSTANT OPTIMIZING VULCANIZATION OF RUBBER COMPOUND AND VULCANIZING APPARATUS
JP09049817H	February, 1997			METHOD FOR INSPECTING INSIDE OF VEGETABLE AND FRUIT FOR QUALITY
JP09076251	March, 1997			METHOD FOR MEASURING VULCANIZATION REACTION AND METHOD AND APPARATUS FOR PREPARING RUBBER PRODUCT
JP11506838H	June, 1999
JP2001018240	January, 2001			RESIN CASTING APPARATUS
WO/1989/003047	April, 1989			APPARATUS AND METHODS FOR MEASURING PERMITIVITY IN MATERIALS
WO/1995/034945	December, 1995			A METHOD AND AN APPARATUS FOR CONTROLLING THE TRANSFER OF HIGH FREQUENCY POWER FROM AN ELECTRIC AC GENERATOR TO AN ITEM TO BE TREATED
WO/1996/028741	September, 1996			DETERMINING THE DIELECTRIC PROPERTIES OF WOOD
WO/1996/039623	December, 1996			MONITORING OF RESISTANCE IN POLYMERS
WO/1997/004299	February, 1997			PREDICTION OF THE PROPERTIES OF BOARD BY USING A SPECTROSCOPIC METHOD COMBINED WITH MULTIVARIATE CALIBRATION
WO/1998/039639	September, 1998			METHOD AND DEVICE FOR DETERMINING A PLURALITY OF QUALITY VARIABLES WHICH DESCRIBE THE CONDITION OF AN ORGANIC MATTER
WO/1999/013346	March, 1999			METHOD AND APPARATUS FOR IN-SITU MEASUREMENT OF POLYMER CURE STATUS
WO/2000/079266	December, 2000			MOISTURE MEASUREMENT CONTROL OF WOOD IN RADIO FREQUENCY DIELECTRIC PROCESSES
WO/2001/001056	January, 2001			SPECIAL STICKER AND PROCEDURE FOR DETECTING ACOUSTIC EMISSION (AE) OR ULTRASONIC TRANSMISSION DURING DRYING OF LUMBER
WO/2003/067275	August, 2003			MOISTURE AND DENSITY DETECTOR (MDD)
WO/2005/069021	July, 2005			PERMITTIVITY MONITOR USES ULTRA WIDE BAND TRANSMISSION

“Wellons True Capacitance Moisture Meter System” Wellons, Inc. 2005; 1 page.
“Automatic, Computer Controlled, Processing of Advanced Composites”; Defense Small Business Innovation Research (SBIR) Program; Apr. 7, 1988; 25 pgs.
“Critical Point Control/Statistical Quality Control Software Module”; Micromet Instruments; 1993; 2 pgs.
“Dielectric Cure Testing on Polyester Bulk Molding Compound”; Holometrix Micromet; 2001; 3 pgs.; http://www.holometrix.com/holometrix/m—materialtest.asp.
“Dielectric Sensors”; NETZSCH; Feb. 21, 2002; pgs.
“Eumetric System III Microdielectrometer . . . ”; Holometrix Micromet; 2001; 5 pgs.
“ICAM-1000—In-mold Monitoring For SPC, SQC, and CPC (Critical Point Control) of Thermoset Molding Operations”; Micromet Instruments, Inc.; at least as early as Mar. 1990; 4 pgs.
“ICAM-1000 Industrial Cure Analysis & Monitoring System”; Micromet Instruments, Inc.; Aug. 1, 1991; 1 pg.
“ICAM-2000 Multi-Channel Cure Analyzer”; Micromet Instruments; 1993; 2 pgs.
“Lockheed Signature Process Control for Composites Proposal”; Ketema Programmed Composites, Inc.; Jul. 1, 1993; pp. 1-12.
“MDE Series 10 Cure Monitor”; Holometrix Micromet; at least as early as Mar. 15, 2000; 2 pgs.
“Mono-Probe”; TYT-NAM-MON; Oct. 27, 2000; 1 pg.
“Northrup Aircraft Division RTM System Proposal”; Ketema Programmed Composites, Inc.; Apr. 1, 1993; 13 pgs.
Prepeg Cure Characterization Using Simultaneous Dynamic Mechanical Analysis-Dielectric Analysis (DMA-DEA); Perkin Elmer Thermal Analysis Newsletter; (date unknown); 4 pp.
“Product Selection Grid”; Holometrix Micromet; 2001; 1 pg.; http://www.holometrix.com/holometrix/m—prgrid.asp.
“SmartTrac”; Innovative Aftermarket Systems, Inc.; 2001; 2 pgs. http://www.ias-inc.net/pages/products/smart.html.
“Textron Aerostructures Autoclave Process Control Proposal”; Ketema Programmed Composites, Inc.; Feb. 12, 1993; 16 pgs.
“The Eumetric System III Microdielectrometer”; Micromet Instruments, Inc.; Sep. 1991; 4 pgs.
“Tool Mount Sensors”; http://www.micromet.com/home/rds.htm; (date unknown); 2 pp.
“Tool Mount Sensors”; NETZSCH; Feb. 21, 2002; 2 pgs.
“Vulcanization of Natural Rubber”; NETZSCH; Nov. 8, 2001; 2 pgs.
Baumgartner et al.; “Computer Assisted Dielectric Cure Monitoring in Material Quality and Cure Process Control”; SAMPE Journal; Jul./Aug. 1983; pp. 6-16.
Buczek; “Considerations in the Dielectric Analysis of Composites”; 40th International SAMPE Symposium; May 8-11, 1995; pp. 696-710.
Buczek; “Self-Directed Process Control System for Epoxy Matrix Composites”; 40th International SAMPE Symposium; May 8-11, 1995; 8 pgs.
Day; “Cure Characterization of Thick Polyester Composite Structures Using Dielectric and Finite Difference Analysis”; Composite Material Technology; ASME; 1993; PD-vol. 53:249-252.
Desanges; “Changes in the Electrical Properties of Natural Rubber/Carbon Black Compounds During Vulcaniation”; Revue Generate du Caoutchouc; Dec. 1957; 34(12); pp. 631-649.
International Preliminary Report on Patentability for International (PCT) Patent Application No. PCT/US2005/008254, issued Sep. 13, 2006, 10 pages.
International Search Report for International (PCT) Patent Application No. PCT/US02/32480, issued Mar. 20, 2003, 5 pages.
James “Dielectric Properties of Lumber Loads in a Dry Kiln” United States Department of Agriculture, Research Paper FPL 436; 1983; p. 1-16, cover, abstract and final page (19 pages total).
James et al. “In-Kiln Moisture Monitoring Systmes” In: Robertson, Doris, coord. Computer automation for sawmill profit: Proceedings 7333: Oct. 4-6, 1982; Norfolk, VA. Madison, WI: Forest Products Research Society; 1984: p. 91-94.
Johnson et al.; “Production Implementation of Fully Automated, Closed Loop cure Control for Advanced Composite Strucutres”; 34th International SAMPE Symposium; May 8-11, 1989; pp. 373-384.
Keller et al.; “Computer Controlled Processing of Composites Utilizing Dielectric Signature Curves”; SAMPE Journal; Sep./Oct. 1992; 28(5); pp. 25-33.
Keller et al.; “Real Time, In-Situ Dielectric Monitoring of Advanced Composites Curing Processes”; Programmed Composites, Inc.; Aug. 1, 1987; 63 pgs.
Khastgir; “A Comparative Study of Step Curing and Continuous Curing Methods”; Rubber World; Jan. 1994; pp. 28-31.
O'Conor et al.; “Update to the Jun. 1990 Confidential Descriptive Memorandum”; Micromet Instrument, Inc.; Dec. 1, 1990; 17 pgs.
Persson; “A Novel Method of Measuring Cure—Dielectric Vulcametry”; Plastics and Rubber Processing and Applications; 1987; 7(2); pp. 111-125.
Rajeshwar; “AC Impedance Spectroscopy of Carbon Black-Rubber Composites”; Department of Chemistry and Biochemistry at The University of Texas as Arlington; Sep. 21-24, 1999; 13 pgs.
SmartTrac Advertisement, Automotive News; May 21, 2001, 1 pg.
Thermokinetics; NETZSCH; ; Nov. 8, 2001, 2 pgs.
Wagner Electronics—Press Releases; 2001, 2002, 2004, and 2005; 5 pages; Wagner Products Inc.
English Translation of the First Office Action for Chinese Patent Application No. 02829296.0, issued Nov. 17, 2006.
English Translation of the Second Office Action for Chinese Patent Application No. 02829296.0, issued Nov. 16, 2007.
Official Action (including translation) for Japanese Patent Application No. 2004-519513, mailed Jun. 17, 2008.
Notification of the Decision to Grant a Patent Right for Patent for Invention, including Notification of Fullfilling of Registration Formality (including translation) Chinese Patent Application No. 02829296.0, issued Apr. 25, 2008.

Shechtman, Sean P.

Sheridan Ross P.C.
Dupray, Dennis

RELATED APPLICATIONS

This is a continuation application of a pending prior U.S. patent application Ser. No. 10/800,079, filed Mar. 11, 2004, which is a continuation-in-part application of prior U.S. patent application Ser. No. 10/666,433 filed Sep. 18, 2003, which is a continuation-in-part of U.S. patent application Ser. No. 10/267,197 filed Oct. 8, 2002, now U.S. Pat. No. 6,855,791 issued on Feb. 15, 2005, which claims the benefit of U.S. Provisional Patent Application No. 60/394,736, filed Jul. 9, 2002. U.S. patent application Ser. No. 10/666,433 is also a continuation-in-part of both U.S. patent application Ser. No. 09/815,342, filed Mar. 21, 2001, and U.S. patent application Ser. No. 10/102,614, filed Mar. 19, 2002, now U.S. Pat. No. 6,774,643 issued on Aug. 10, 2004, which claims the benefit of U.S. Provisional Patent Application No. 60/278,034, filed Mar. 21, 2001; the entire disclosures of the above-cited prior applications are considered to be part of the present application and accordingly are hereby fully incorporated by reference.

What is claimed is:

1. A process for curing a plurality of curable parts composed of a compound that is curable using heat, comprising: a) curing, at each of a plurality of predetermined specifications for a corresponding curing environment, a corresponding sample of the compound for obtaining a corresponding curing time indicative of the cured sample having one or more predetermined desired or specified mechanical properties; b) for each specification (S) of the plurality of predetermined curing environment specifications, curing a corresponding amount of the compound while obtaining measurements of curing conditions indicative of dielectric or impedance signals transmitted through the corresponding amount, wherein the corresponding amount is cured for obtaining a corresponding part, or cured in a witness cavity for a corresponding curing part, wherein the measurements are used to produce a corresponding process curve for the compound and the specification S of the corresponding curing environment; c) obtaining data for predicting a curing end time, the data for predicting dependent upon a result of a correlation performed between; (i) the curing times of the cured samples, and (ii) a collection of evaluations, each evaluation for representing at least one characteristic of one of the process curves, the at least one characteristic being different from a curing time; and d) for a plurality of additional amounts of the compound, curing each additional amount corresponding to an additional part while obtaining curing condition measurements by dielectric or impedance signals transmitted through the additional amount being cured, wherein the data for predicting is combined with the curing condition measurements of the addition amount for thereby determining when to terminate the curing of the additional amount so that the additional part has the one or more predetermined desired or specified mechanical properties.

2. The process of claim 1, wherein the dielectric or impedance measurements are obtained using a circuit that is non-bridged.

3. The process of claim 1, further including determining the correlation by statistically correlating the curing times of the samples with the one or more characteristics of the process curves.

4. The process of claim 1, wherein the correlation is accomplished using a rheometric instrument for identifying the one or more predetermined desired or specified mechanical properties when curing the samples.

5. The process of claim 1, wherein for at least one of the corresponding amounts, further including determining a Maximum Value, and/or a Time of Maximum Value in a predetermined time segment when curing the at least one corresponding amount.

6. The process of claim 1, wherein for at least one of the corresponding amounts, further including determining a Minimum Value, and/or a Time of Minimum Value in a predetermined time segment when curing the at least one corresponding amount.

7. The process of claim 1, wherein for at least one of the additional parts, the data for predicting includes a rate of a cure that is determined using a linear least-squares best fit extending over a predetermined time segment of the curing condition measurements of a process curve (PC) for the at least one additional part, wherein the linear least squares best fit is used to obtain a slope (in) of a line equation: y =mx +b that is a linear approximation of the process curve PC in the predetermined time segment, wherein the variable x in the line equation represents a time in the predetermined time segment, the variable y in the line equation represents an impedance value that approximates the process curve PC at the time for the variable x, and the constant b in the line equation represents an impedance value that approximates the process curve PC when x is zero.

8. The process of claim 1, wherein for at least one of the additional parts, the data for predicting includes a rate of a cure that is determined using an exponential best fit over a predetermined time segment of the curing condition measurements of a process curve (PC) for the at least one additional part, wherein the exponential best fit is used to obtain a damping coefficient, x, from an equation: y =Ae^αx, that is an approximation of the process curve PC in the predetermined time segment, wherein the variable x in the equation represents a time in the predetermined time segment, the variable y in the equation represents an impedance value that approximates the process curve PC at the time for the variable x, and the constant A in the equation represents an amplitude coefficient.

9. The process of claim 1, wherein for at least one of the additional parts, the data for predicting includes a rate of a cure that is determined using an exponential best fit over a predetermined time segment of the curing condition measurements of a process curve (PC) for the at least one additional part, wherein the exponential best fit is used to obtain an amplitude coefficient, A, from an equation: y =Ae^αx, that is an approximation of the process curve PC in the predetermined time segment, wherein the variable x in the equation represents a time in the predetermined time segment, the variable y in the equation represents an impedance value that approximates the process curve PC at the time for the variable x, and the constant a in the equation represents a damping coefficient.

10. The process of claim 1, wherein an integrated area under one of the corresponding process curves or a portion of the one process curve is used to determine the data for predicting.

11. The process of claim 1, in which the dielectric or impedance measurements include impedance (Z), phase angle (Φ), resistance (R), reactance (X), conductance (G) or capacitance (C) values as the dependent variable of the process curve as plotted against time as the independent variable.

12. The process of claim 1, wherein the correlation is made between: (a) mathematical measurements of the corresponding process curves, and (b) rheometric property measurements of the samples, wherein the desired or specified part mechanical properties of the samples include one or more of: tensile strength, compression set, dynamic stiffness, and elastic torque.

13. The process of claim 12, wherein data for predicting includes a modifier which provides a linear adjustment to a T90 or rheometric correlation equation.

14. The process of claim 1, wherein the curing condition measurements are made from the dielectric or impedance signals being transmitted at a frequency in a range of about 10 Hz to 100 kHz.

15. The process of claim 1, in which said compound is selected from the group consisting of: styrene-butadiene, polybutadiene, polyisoprene, ethylene-propylene, butyl, halobutyl, nitrile , polyacrylic, neoprene, hypalon, silicone, fluorocarbon elastomers, polyurethane elastomers, and mixtures thereof.

16. The process of claim 15, in which fillers for the compound include carbon black, clays, oils, and silicas.

17. The process of claim 1, in which the said process is controlled using a computer.

18. The process of claim 17, in which said computer controls the process by receiving a start cure signal from vulcanization equipment and based on a predefined software algorithm sends an end cure signal back to the vulcanization equipment.

19. The process of claim 1, wherein each of the corresponding amounts, and the additional amounts are cured using vulcanization equipment and associated tooling, wherein an impedance measuring means, for measuring impedance related signals indicative of a curing state of each of the corresponding amounts and the additional amounts, is included in one of the vulcanization equipment and the associated tooling.

20. The process of claim 19, wherein the impedance measuring means includes a primary sensor electrode coupled with an opposing grounded surface electrode, which is part of the vulcanization equipment or the associated tooling.

21. The process of claim 20, wherein the impedance measuring means includes an impedance sensor in contact with each of the corresponding amounts, and the additional amounts being cured.

22. The process of claim 21, in which the impedance sensor includes an additional guard electrode to help preclude the primary electrode from fringing or becoming non-linear.

23. The process of claim 22, wherein the primary and guard electrodes are separated from each of the corresponding amounts, and the additional amounts being cured by alumina ceramic or other stable and abrasion resistant dielectric material.

24. The process of claim 20, wherein the primary sensor electrode, a guard electrode, and a housing are separated electrically from each other by a dielectrically stable polymer, and alumina ceramic.

25. The process of claim 20, wherein the primary sensor electrode, a guard electrode, and a housing are fused together and separated electrically from each other by glass or glass doped with alumina ceramic.

26. The process of claim 20, in which the primary sensor electrode and a guard electrode are embedded in a metallized and layered ceramic circuit.

27. The process of claim 20, wherein the primary sensor electrode, a guard electrode, and a housing are: (a) press fit together, and (b) separated electrically from each other and each of the corresponding amounts, and the additional amounts being cured by a diamond coating.

28. The process of claim 18, in which said vulcanization equipment includes one of: injection molding machines, compression and transfer molding presses, belt making presses, autoclaves, and tire molding machines.

29. The process of claim 19, wherein said associated tooling includes: injection molds, compression and transfer molds, mandrels, platens, and tire molds.

30. The process of claim 18, wherein the dielectric or impedance signals are transmitted using an dielectric or impedance means that includes more than one sensor to monitor the process, wherein one of the sensors that lags from cycle-to-cycle is used to control the termination of the curing of one or more of the additional amounts.

31. The process of claim 4, wherein the rheometric instrument includes one of an oscillating disk rheometer and a moving die rheometer.

32. The process of claim 24, wherein the dielectrically stable polymer includes cyanate ester.

33. The process of claim 1, wherein the correlation determines how well a distribution of the curing times corresponds to a distribution of the evaluations.

34. The process of claim 1, wherein for each of the plurality of predetermined curing environment specifications, the corresponding sample is different from the corresponding amount.

35. A process for curing a plurality of curable parts composed of a compound that is curable using heat, comprising: curing, at each of a plurality of predetermined specifications for a corresponding curing environment, a corresponding sample of the compound for obtaining a corresponding curing time indicative of the cured sample having one or more predetermined desired or specified mechanical properties; for each specification (S) of the plurality of predetermined curing environment specifications, curing a corresponding amount (AMTs) of the compound at the specification S while obtaining corresponding measurements of curing conditions indicative of dielectric or impedance signals transmitted through the corresponding amount AMTs; wherein each corresponding amount AMTs is cured using first heat curing equipment that is different from the heat curing equipment for curing the samples, wherein the corresponding measurements are used to produce a corresponding process curve for the compound and the specification S of the corresponding curing environment; obtaining data for predicting a curing end time, the data for predicting dependent upon a result of a correlation performed between: (i) the curing times of the cured samples, and (ii) a collection of evaluations, each evaluation for representing at least one characteristic of one of the process curves, the at least one characteristic being different from a curing time; and for a plurality of additional amounts of the compound, curing each additional amount corresponding to an additional part, using first heat curing equipment, while obtaining curing condition measurements by dielectric or impedance signals transmitted through the additional amount being cured, wherein the data for predicting is combined with the curing condition measurements of the additional amount for thereby determining when to terminate the curing of the additional amount so that the additional part has the one or more predetermined desired or specified mechanical properties.

RELATED FIELD OF THE INVENTION

This invention relates to a new and improved process and apparatus for monitoring and controlling the vulcanization of natural and synthetic rubber compounds containing fillers such as carbon black, oils, clay, and the like. Typical base rubber polymers which may be employed include styrene-butadiene, polybutadiene, polyisoprene, ethylene-propylene, butyl, halobutyl, nitrile, polyacrylic, neoprene, hypalon, silicone, fluorocarbon elastomers, polyurethane elastomers, natural rubber and hydrogenated nitrile-butadiene rubber, and mixtures thereof.

BACKGROUND OF THE INVENTION

Heretofore methods of applying fixed process parameters to the processing of rubber polymeric compounds during vulcanization have resulted in both reduced productivity due to overly conservative cure times and poor product uniformity due to the inability of the fixed process parameters to accommodate the inherent variability in the process.

The relationship of dielectric properties and the state and rate of the cure of polymers is well known. Related publications, incorporated herein fully by reference, in this field are:

U.S. PATENT DOCUMENTS

	4,344,142	August 1982	Diehr, II et al.
	4,373,092	February 1983	Zsolnay
	4,399,100	August 1983	Zsolnay, et al.
	4,423,371	December 1983	Senturia, et al.
	4,496,697	January 1985	Zsolnay, et al.
	4,510,103	April 1985	Yamaguchi, et al.
	4,551,807	November 1985	Hinrichs, et al.
	4,723,908	February 1988	Kranbuehl
	4,777,431	October 1988	Day, et al.
	4,773,021	September 1988	Harris, et al.
	4,868,769	September 1989	Persson, et al.
	5,032,525	July 1991	Lee, et al.
	5,219,498	June 1993	Keller, et al.
	5,317,252	May 1994	Kranbuehl
	5,486,319	January 1996	Stone, et al.
	5,528,155	June 1996	King, et al.
	5,872,447	February 1999	Hager, III

OTHER PUBLICATIONS

• • Changes in the Electrical Properties of Natural Rubber/Carbon Black Compounds during Vulcanization, 1957, H. Desanges, French Rubber Institute
  • A novel method of measuring cure—dielectric vulcametry, 1986, Sture Persson, The Plastics and Rubber Institute, England
  • A comparative study of step curing and continuous curing methods, 1994, D. Khastgir, Indian Institute of Technology
  • AC Impedance Spectroscopy of Carbon Black-Rubber composites, 1999, K. Rajeshwar, University of Texas at Arlington

The prior art has clearly established a relationship between the dielectric (herein also referred to as “impedance”) properties of polymeric resins and the curing of such resins. For example, these resins exhibit rheometric and chemical behavior such as melt, volatile release, gelation, and crosslinking that can be recognized by dielectric changes. However, unlike polymeric resins, rubber polymeric compounds do not melt or exhibit gelation during cure or vulcanization and are therefore much more difficult to characterize, monitor and control by analysis of dielectric characteristics. Moreover, none of the prior art associated with polymeric rubber curing (also referred to as “vulcanization”) addresses the practical aspects of taking measurements directly in the production process, especially in the highly abrasive and high pressure environment of injection molding. Additionally the prior art does not show how to use the electrical data obtained to achieve closed-loop control of the curing or vulcanization process of, e.g., polymeric rubber over a wide range of molding methods and conditions.

The prior art also does not show how to compensate, in the vulcanization process: (a) for variations in polymeric rubber curing compounds from batch to batch and within batches, and (b) for differences in vulcanizate thickness. Additionally, the prior art does not compensate for additional variables, which are introduced into the vulcanization process by the nature of the vulcanization equipment, tooling, and thermal history of polymeric rubber curing compounds.

Moreover, the prior art uses dielectric or impedance measuring apparatus, which employ opposing and parallel electrodes of precise area and separation distance, and in which, the electrodes are in direct contact with the rubber compound. Although such electrodes and apparatus provide a means for measuring impedance properties during cure, they are entirely impractical for use in a production environment. For example, many rubber components are produced using injection molding technology which subjects the sensors to pressures up to 30,000 psi and temperatures up to 425° F. Moreover, due to the flow inside the mold during injection, in addition to the carbon and silica fillers present in many rubber compounds, the sensor must survive in a highly abrasive environment. Finally, the sensor must also be able to survive mold cleaning via typical cleaning methods such as CO ₂ and plastic bead blast.

Accordingly, it is desirable to have an apparatus and method for alleviating the above described drawbacks to using impedance data measurements for monitoring and controlling the vulcanization process for rubber polymeric compounds. In particular, it is desirable for the impedance sensor provided at the vulcanization equipment to be both extremely rugged and more easily used in that the electrodes: (a) need not be of precise area, (b) need not be of precise separation distance from one another, and (c) need not be in direct contact with the material being vulcanized. In addition, it would be desirable to have a method for correlating the desired properties of a rubber polymeric compound product with impedance measurements.

DEFINITIONS AND TERMS

Numerous technical terms and abbreviations are used in the description below. Accordingly, many of these terms and abbreviations are described in this section for convenience. Thus, if a term is unfamiliar to the reader, it is suggested that this section be consulted to obtain a description of the unknown term.

• Rubber Polymeric Compounds (equivalently, “Polymeric Rubber Compounds”, and “Rubber Compounds” herein): Typical base rubber polymeric compounds including (but not limited to) styrene-butadiene, polybutadiene, polyisoprene, ethylene-propylene, butyl, halobutyl, nitrile, polyacrylic, neoprene, hypalon, silicone, fluorocarbon elastomers, polyurethane elastomers, natural rubber and hydrogenated nitrile-butadiene rubber (HNBR), and mixtures of such rubber compounds having fillers such as recited hereinabove.
• ODR: Oscillating Disk Rheometer—A device that measures the Theological characteristics (elastic torque, viscous torque, etc.) of a polymer during vulcanization, using an oscillating disk to apply stress to the curing polymer.
• MDR: Moving Die Rheometer—A device that measures the rheological characteristics (elastic torque, viscous torque, etc.) of a polymer during vulcanization, using a moving die to apply stress to the curing polymer.
• Rheometric instrument: A device that measures the rheological characteristics (elastic torque, viscous torque, etc.) of a polymer during vulcanization.
• T90 Time: The time, as measured in an ODR or MDR at which a given rubber compound at a given curing temperature, reaches 90% of its ultimate elastic torque value.
• Designed Experiment: A single set of related experiments drawn up from one of the types of designs to be found in the body of methods for design of experiments described hereinbelow in the Detailed Description.
• Exponential Dampening: The damping coefficient (□) as defined by a best exponential fit to a set of raw data, where the fit curve (y) is described by the equation:
  y=Ae ^−αt , where t is time.
• Exponential Amplitude Coefficient: The amplitude coefficient (A) as defined by a best exponential fit to a set of raw data, where the fit curve (y) is described by the equation
  y=Ae ^−αt , where t is time.
• Topological Features of Impedance Related Data: Recognizable and distinct features within a cure curve, such as a peak (maxima), valley (minima) or flat (no slope).
• Low CTE Metallic Material: A material with a low coefficient of thermal expansion.
• Tool Steel: A steel suitable for use in making injection and compression molds such as AISI Type A2 Tool Steel.
• Witness cavity: A small cavity attached to but separate from injection mold for the rubber polymeric compound part being produced, wherein this small cavity is for allowing in-mold vulcanization sensor measurements of a rubber compound cure without the sensor being in direct contact with the curing part. In particular, a dielectric sensor in the witness cavity does not directly sense any of the parts that are being produced. Instead, the sensor monitors the cure of the rubber polymeric compound in the witness cavity.
• R-square (R ² ): R-square (also known as the coefficient of determination) is a statistical measure of the reduction in the total variation of the dependent variable due to the independent variables. An R-square close to 1.0 indicates that a model (also referred to herein as an “algorithm”) accounts for almost all of the variability in the respective variables.
• Confidence interval: A range of values within which a particular number of interest is desired to be, at some specific level of probability such as 95%.

SUMMARY OF THE INVENTION

The present invention is a method and system for controlling the vulcanization (herein also denoted “curing”) of rubber polymeric compounds. In particular, the present invention includes novel features for monitoring the polymerization and determining in real-time the optimum cure time for the production of parts made from rubber polymeric compounds (herein also denoted as “polymeric rubber compounds” or merely “rubber compounds”). According to the present invention, during the curing of rubber polymeric compounds, data streams of impedance values are obtained (denoted herein as “impedance data streams”), wherein these values are indicative of impedance measurements obtained from one or more capacitor circuits (CC). Each of the capacitor circuits is operatively configured so that such a rubber polymeric compound becomes part of the capacitor circuit, and in particular, becomes a dielectric for the circuit. For each of the impedance data streams there is a corresponding graphical representation for presenting the particular impedance properties versus time that are provided by the impedance data stream. Such graphs are denoted “process curves” herein, and each such process curve is generally identical in informational content to the impedance data stream from which the process curve is derived. Accordingly, in many embodiments of the present invention utilizes derived characteristics of the impedance data streams that is more easily described in terms of their graphical representations as process curves, e.g., shape and/or geometric curve characteristics such as slopes and/or an area under such a process curve. Note that such impedance data streams can be representative of a time series of one or more of the following impedance types of impedance values: the impedance (Z), phase angle (ø), resistance (R), reactance (X), conductance (G), and/or capacitance (C). Thus, the impedance data streams (and their related process graphs) are derived from the signal responses output by the activation of one or more of the capacitor circuits CC, wherein such activation is the result of at least one, and more generally, a plurality of signals of different frequencies being input to such capacitor circuit(s). Thus, in some embodiments of the present invention, each of the process curves may be obtained from a single, and in general different, signal frequency input to the capacitor circuit(s), and the corresponding shape (or other computational characteristics) of each of a process curves may be used in monitoring, controlling and/or predicting an outcome of a curing process for polymeric rubber compounds.

In some embodiments of the present invention, various time series capacitor circuit output data components (i.e., impedance (Z), phase angle (ø), resistance (R), reactance (X), conductance (G), or capacitance (C)) are separately processed, thereby resulting in a process curve with distinctive shape (or other features) for each of these components. Accordingly, it is an aspect of the present invention that such features from impedance (Z), phase angle (ø), resistance (R), reactance (X), conductance (G), or capacitance (C) graphs (e.g., plotted versus time) can be used for monitoring and controlling the cure time by measuring a portion of the process curve and calculating or predicting the optimum cure time. Thus, since a particular shape (or other “computational features” such maxima, minima, slope, rate of slope, portion having substantially zero slope, inflection point, the area under a portion of the curve, etc.) of such process curves may be substantially repeatable for curing a particular rubber polymeric compound or material, such features can be effectively utilized in a mass production environment for producing consistent high quality cured products (e.g., seals, gaskets, and tires).

Moreover, it is a further aspect of the present invention that for a given rubber polymeric material to be cured, the present invention can identify at least some of the computational features of these process curves substantially independently of the configuration of the product being produced by utilizing dielectric properties obtained from a “witness cavity” incorporated into the runner system (i.e., the flow path within the mold that channels the rubber to the product cavities) of the mold, as one skilled in the art will understand. In particular, such computational features can be correlated with the chemical and rheometric changes occurring during the curing process.

Thus, although such process curves may vary in amplitude and duration (e.g., due to cured part thickness, thermal history, mold temperature and heat rate, curative level, compound batch variations, and various other factors), the present invention may be used for monitoring, controlling and/or predicting cure states of products in a mass production environment wherein the products being produced may be subject to significant process and rubber compound variation.

For example, for a particular sample or product to be cured, properties of one or more of the above described process curves can be calculated for a specific measurement period wherein a portion of the data corresponding to each process curve of the sample may be correlated to a desired final cure state of the product. Thus, such a correlation can be used to establish a time for appropriately curing a part in production, wherein the part is substantially identical to the sample. In particular, the present invention predicts cure times as will be described more fully herein below.

In one embodiment of the present invention, it has been found that during the curing of a polymeric rubber compound, there is a distinctive capacitance versus time process curve, and/or a distinctive conductance versus time process curve produced. Thus, for a part molded from a particular rubber polymeric compound, the shape of at least one of the corresponding distinctive capacitance and/or conductance process curves (for the particular rubber polymeric compound) may be consistent enough for predicting the state of the part during vulcanization. Thus, although such process curves for individual parts may vary in amplitude and time ordinates (principally due to part thickness, thermal history, mold temperature and heat rate, curative level, and various other factors), the general shape of such curves can be used in predicting the state of vulcanization. That is, the shape of such process curves can be correlated to the chemical and physical changes occurring during the curing process.

For example, the initial slope of at least one of the distinctive capacitance and conductance process curves for a rubber compound being cured is associated with the rate of the curing reaction and this initial slope can be used to establish or predict the preferred or correct cure time for the polymeric rubber part being produced. In addition, the area under such a process curve or a portion of the process curve may be associated with the cure “energy” and can be also be used to control or predict the cure time. For certain rubber compounds, one or more of the capacitance and conductance process curves exhibit a shape including a “VALLEY” and/or a “PEAK” which can be used to control or predict the cure time. Moreover, it is an aspect of the present invention to employ software algorithms for identifying process curve features, wherein such algorithms compute process curve characteristics such as linear fit coefficients, polynomial fit coefficients, and logarithmic fit coefficients so that these computed characteristics can be used to control the cure time and thereby achieve a desired part property such as a predetermined range of tensile strength and/or compression set.

In one embodiment, the present invention (FIG. 1) includes an equipment enclosure 5 having the following high level components:

• • (1.1) Data acquisition hardware (e.g., data acquisition card 35 as shown in FIG. 13), and control hardware (e.g., for implementing the control system 39 , also shown in FIG. 13, thereon);
  • (1.2) A host computer 9 with human machine interface software, and signal conditioning and control software.
    Additionally, FIG. 1 shows vulcanizing equipment 45 having the following high level component:
  • (1.3) Capacitor 68 formed from: (i) impedance sensor(s) 17 which is placed directly adjacent to the rubber compound 16 being vulcanized, (ii) a grounded capacitor plate 64 , and (iii) the rubber compound 16 as the capacitor dielectric.

Furthermore, this embodiment may include an expert system and/or rule base software for recognizing topographical features or mathematical properties and/or patterns of the impedance process curve(s).

The data acquisition and control hardware of the embodiment of FIG. 1 provides a means to generate a plurality of sinusoidal signals of various frequencies, which are multiplexed onto the impedance sensor 17 . The frequency range applied then allows for a spectrum of conductance and capacitance measurements to be captured as output from the impedance sensor 17 . Thus, the conductance and capacitance readings (equivalently, process curves) are specific to the rubber polymeric compound under cure, in that the dipolar and/or carbon constituents of the compound will generate a pattern of dielectric responses specific to the rubber polymeric compound. Accordingly, a high level representation of an algorithm that uses such readings of impedance characteristics for controlling the vulcanization process is shown in FIG. 2.

Note that in the present embodiment of the invention (i.e., FIG. 1), each impedance sensor 17 includes a primary electrode 10 (FIG. 3) that serves as a capacitor plate for the capacitor 68 . An additional electrode 11 rings the primary electrode 10 and acts as a shield that precludes excessive fringing of the electrical field to the adjacent tool surface in which the sensor 17 is typically flush mounted. Both electrodes 10 and 11 are embedded in a ceramic body (not shown) and are separated from the rubber polymeric compound 16 being evaluated by a thin layer of alumina ceramic 13 or other suitable material, which is dielectrically stable over the temperature range of the vulcanizing process. Any other planar or semi-planar conductive surface within the production process (typically an opposing mold surface) can serve as the opposing plate (i.e., ground plate 64 ) of the capacitor 68 and acts as the third electrode for capacitively coupling with the primary electrode 10 . Thus, since the opposing plate is grounded, when a complex current is driven through a resistor 19 (FIG. 3) to ground, this current passes through the rubber compound 16 which is the dielectric within the formed capacitor. The complex voltage across the resistor 19 is then measured with a high precision amplifier 36 . The resulting signal is then demodulated via software component(s) collectively labeled 23 (FIG. 1) into its complex impedance components (e.g., conductance and capacitance).

It is a further aspect of the present invention, that in various embodiments and for certain rubber compounds, the corresponding shape of one or more of the above described process curves may exhibit a “maxima” and/or a “minima” at a given time which can also be used to infer useful information in monitoring, controlling and/or predicting the proper cure time.

It is a further aspect of the present invention that in various embodiments and for certain rubber compounds, one or more (preferably a plurality) of “evaluators” are provided for outputting values related to the cure time of a part. Such evaluators may be, e.g., the corresponding slope or integrated area under one or more of the above described process curves. The output from each of the evaluators can be correlated with known curing times of rubber compound samples to thereby determine a predictive effectiveness of the evaluator. In one embodiment, the known curing times can be T90 times, T75 times, or T50 times that are determined by obtaining rheometric measurements of the samples during their curing. The evaluators that exhibit a high degree of correlation to physically measured rheometric curing properties of the samples are used to infer useful information in monitoring, controlling and/or predicting the proper cure time of rubber compound molded parts such as parts that are mass produced. In at least one embodiment of the present invention, the output from two or more (e.g., four) evaluators providing the highest degree of correlation with the measured rheometric curing properties are combined (e.g., as a linear combination) to yield an even better predictor for predicting part curing times.

It is a further aspect of the present invention that embodiments thereof include signal processing and other software and hardware (“components”) for both deriving such computational features (e.g., maxima and/or minima) of the process curves obtained from a rubber polymeric compound being cured, and utilizing such features to determine, in real-time, the optimum cure time for each production cure cycle.

Moreover, it is an aspect of the present invention that such cure times are determined for achieving a desired property such as tensile strength, dynamic stiffness, and/or compression set in the resulting cured part.

Accordingly, the present invention may be described by the following aspects:

• • Aspect 1: A method for curing a part composed a rubber compound composed of natural or synthetic rubber together with fillers using vulcanization equipment, comprising:
    • (a) measuring curing conditions by dielectric or impedance means applied on opposite sides and through the rubber part or a witness cavity representing the part during the curing process to produce a process curve for a specific rubber compound, wherein said process curve is correlated with one or more rheometric properties of the rubber compound and one or more desired or specified mechanical properties of the rubber part;
    • (b) analyzing the process curve for the specific rubber compound with a software algorithm which defines and quantifies a correlation relationship between the process curve and the rheometric properties of the rubber compound and the desired or specified part mechanical properties; and
    • (c) applying the correlation relationship in real-time to end the curing process and thereby produce rubber part(s) of uniform quality and with reduced process cycle time.
  • Aspect 2: A method for curing one or more parts, comprising:
    • determining, for each evaluator of a plurality of evaluators, a part curing predictive effectiveness;
    • wherein for each of said evaluators (E), said step of determining determines, for a plurality of curing conditions, a correspondence between (a1) and (a2) following:
      • (a1) outputs by the evaluator E, wherein for each curing condition (CC _j ) of the curing conditions, there is a portion of the outputs obtained when the evaluator E is provided with a corresponding activation input that includes a sequence of impedance responses from a device providing signals indicative of impedance measurements of a rubber compound (RC), wherein the rubber compound RC is being cured:
        • (i) according to the curing condition CC _j ; and
        • (ii) in curing equipment that is also to be used in curing the part, and
      • (a2) for each curing condition (CC _k ) of the curing conditions, a known curing of a rubber compound for the curing condition CC _k ;
    • providing, for each of a plurality of predetermined frequencies, an electrical current to the device, wherein the device outputs signals indicative of impedance measurements for a rubber compound from which the part is being formed in the curing equipment;
    • receiving, for each of said frequencies, an impedance data stream including a sequence of impedance responses from said device during the curing of the part;
    • for each of one or more of the curing evaluators, activating the evaluator for obtaining a corresponding result related to a prediction of a cure time of the part, when the evaluator is provided with a corresponding activation input from said impedance data streams;
    • using the corresponding results from the one or more evaluators for obtaining a predicted cure time for the part;
    • wherein a step of identifying is performed prior to said step of using, and said step of identifying identifies at least one of the evaluators (E ₁ ) for predicting a cure time for the part, wherein the predictive effectiveness for E ₁ is better than the predictive effectiveness of at least one other of the evaluators.

Additional aspects, features and benefits of the present invention will become evident from the accompanying drawings and the detailed description herein below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the Invention System Overview Schematic.

FIG. 2 shows the System Operation and Software Algorithm Control Logic.

FIG. 3 shows the Impedance Sensor Excitation and Measurement Schematic.

FIG. 4 shows the sensor arrangement schematically in a mold.

FIG. 5 shows an exploded view of one embodiment of the sensor 17 .

FIG. 6 shows the sensor electrical circuit.

FIG. 7 shows sensor capacitance data collected at 8 frequencies from 3 kHz to 10 kHz.

FIG. 8 shows sensor conductance data collected at 8 frequencies from 3 kHz to 10 kHz.

FIG. 9 shows the correlation between observed T90 times and an impedance measurement.

FIG. 10 Shows the correlation between observed T90 times and 4-term multiple regression of impedance measurements.

FIG. 11 shows a plot of modifier setting versus a specific part property (compression set).

FIG. 12 shows the controller 43 development logic.

FIG. 13 shows a block diagram of the control system 39 .

FIG. 14 shows the control system 39 logic.

FIG. 15 shows plots of typical impedance data obtained by the present invention during the curing of a sample of natural rubber.

FIG. 16 shows curing conditions and resulting rheometry data (i.e., T90 data) for samples of a natural rubber in a designed experiment for determining the effects of various curing conditions on cure rates.

FIG. 17 shows the correlation between the algorithm and rheometry within the natural rubber designed experiment.

FIG. 18 shows the conditions and rheometry for a broad sampling of natural rubber batches and temperatures.

FIG. 19 shows the correlation between the algorithm and rheometry within the broad sampling of natural rubber batches.

FIG. 20 shows average cure times selected by the algorithm under various cure conditions—no porosity observed in any of the algorithm-controlled parts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Key Components of the Invention:

A representative embodiment of the invention can fundamentally be broken into five key components and/or methods, which together form the equipment, tools and processes necessary for monitoring impedance properties in injection and other rubber compound molds or molding environments such as molds for compression molding, transfer molding, and the like. These components and methods are identified as follows:

• • (2.1) A production-capable sensor 17 (e.g., FIGS. 1, 3 and 5 );
  • (2.2) A non-bridged sensor measurement unit 60 (FIG. 3);
  • (2.3) A demodulation method for the sensor signal;
  • (2.4) A method for establishing curing process control algorithms and/or formulas; and
  • (2.5) A real-time curing control system and method for the mass production of rubber compound molded parts.
    Each of these components (2.1) through (2.5) are described hereinbelow.
    (2.1) Production-Capable Sensor 17

The prior art uses dielectric or impedance measuring apparatuses that employ opposing and parallel electrodes of precise area and precise separation distance. Additionally, the metallic prior art electrodes are typically in direct contact with the rubber compound 16 . Although such electrodes and apparatus provide a means for measuring impedance properties during cure, they are entirely impractical for use in a production environment that mass produces molded rubber compound parts. For example, many rubber components are produced using injection-molding technology that subjects the sensors to pressures up to 30,000 psi and temperatures up to 425° F. Moreover, due to the flow inside the molds during injection, and the carbon and silica fillers present in many rubber compounds, the sensor must survive in a highly abrasive environment. Finally, the sensor must be able to survive mold cleaning via the use of CO ₂ bead blast, plastic bead blast, and the like.

Accordingly, it is desirable to have a sensor for alleviating the above described prior art sensor drawbacks to obtaining in-situ impedance data for monitoring and controlling a vulcanization process. In particular, it is desirable for the impedance sensor provided at the vulcanization equipment to be both extremely rugged and more easily used than prior art sensors. More precisely, it is desirable that the electrodes need not be of precise area, need not be of precise separation distance from one another, and need not be in direct contact with the rubber compound being vulcanized.

The impedance sensor 17 (e.g., FIGS. 1 and 3) satisfies the above requirements. The sensor 17 includes a primary electrode 10 that serves as a capacitor plate for a capacitor 68 . An additional capacitor, acting as a guard or shielding electrode 11 , rings the primary electrode 10 of each such sensor 17 (there may be more than one of these sensors). The guard electrode 11 , which is excited along with the electrode 10 , helps to preclude the electrical field induced at the primary electrode 10 of the sensor 17 from fringing or becoming non-linear, as one skilled in the art will understand. The electrodes 10 and 11 are separated from the rubber compound 16 by a thin (e.g., approximately 0.001 to 0.05 inches) ceramic coating 13 (FIG. 3) such as alumina ceramic or other stable dielectric insulator (e.g., dielectrically stable over the temperature range of the vulcanizing process such as, 300° F. to 425° F.). Both electrodes 10 and 11 may be composed of a low CTE metallic material, such as stainless steels, titanium, a nickel-cobalt-iron alloy called Kovar® (which is a trademark owned by CRS Holdings Inc., a subsidiary of Carpenter Technology Corp. of Wyomissing, Pa.), nickel steels, tool steels, tungsten, super alloys, and soft-magnetic alloys., etc embedded in a layered ceramic circuit (not shown).

An alternative embodiment of the sensor 17 is shown in FIG. 5, wherein this embodiment includes a nested construction of A2 tool steel components including a sensor housing 12 , the primary electrode 10 , and the guard electrode 11 , wherein the electrodes are separated radially by a cyanate ester potting material 76 and axially by a thin ceramic coating 13 such as alumina ceramic or other stable dielectric insulator. The ceramic coating 13 may be applied with a thermal spray process (i.e. detonation gun, plasma, or high velocity ceramic (HVOF) spray process, as is well known to those skilled in the art). The ceramic coating 13 provides: (a) electrical isolation for the electrodes 10 and 11 , (b) transmits the compressive loads generated by the curing process to the sensor 17 , and (c) separates the electrodes 10 and 11 from the rubber compound 16 being cured. A coaxial cable 80 is connected to the sensor via an MCX connector 14 such as Johnson Components' MCX connector 14 , p.n. 133-833-401 manufactured by Johnson's Components located at 299 Johnson Ave S.W., Suite 100, Waseca Minn. 56093 which is screwed into the guard electrode 11 . The center conductor 84 mates with a pin machined integral with or press fit into the electrode 10 . In some embodiments of the sensor 17 shown in FIG. 5, the primary electrode 10 , the guard electrode 11 , and the housing 12 , along with an alumina ceramic face 13 may be fused together and separated electrically with glass or glass doped with alumina ceramic. Also, in some embodiments of the sensor 17 shown in FIG. 5, the primary electrode 10 , the guard electrode 11 , and the housing 12 may be coated with a diamond or diamond-like 2 to 4 micron coating such as Casidium as supplied by Anatech Ltd of Springfield, Va., and then press fit together such that the diamond or diamond-like coating provides electrical isolation between these three components, and also between the rubber compound 16 and the face 88 of the sensor 17 .

Therefore the production-ready sensor 17 can be an extremely rugged device, capable of survival in a high pressure, high abrasion, and high temperature environment. The fundamental electrical function of the sensor 17 is to act as a guarded or shielded electrode, forming a single plate of the capacitor 68 (FIG. 1).

Any other planar or semi-planar conductive surface within the interior of the vulcanizing equipment 45 (FIG. 1) can serve as the opposing electrode plate 64 (FIGS. 1, 3 and 13 ) of the capacitor 68 . Note that the opposing plate 64 acts as the third electrode of the capacitor 68 , and thus the opposing plate electrically couples with the primary electrode 10 . Further note that the opposing plate 64 is grounded to electrical ground 25 to provide a common signal reference point.

The vulcanizing rubber compound 16 in the injection mold 18 (FIG. 1) is the dielectric within the formed capacitor 68 , since it is sandwiched between the sensor 17 and the opposing capacitor plate 64 (e.g., a surface of the mold 18 or a metallic insert within the part being molded from the rubber compound 16 ). Since the dielectric properties of the rubber compound 16 change as the compound vulcanizes, the impedance of the formed capacitor 68 changes as well. Thus, the present invention provides a non-invasive method of monitoring and controlling vulcanization in the mold 18 .

FIG. 4 shows how an embodiment of the sensor 17 may be positioned in the mold 18 . In particular, the sensor 17 may be flush mounted in the mold 18 so that the sensor is in electrical contact with the part being molded from the rubber compound 16 . Alternative locations for the sensor 17 are also within the scope of the present invention. For example, the sensor 17 may be located: (a) in electrical contact with the rubber compound 16 in the runner system feeding the interior of the mold 18 , and/or (b) in contact with the rubber compound 16 of a “witness cavity” as described in Definitions and Terms section above. Note that such a witness cavity (not shown) may be particularly important in molding applications where the parts being produced are too small and/or the dimensional specifications are too strict to allow sensor 17 placement directly in contact with the part being produced. However, since the rubber compound 16 in a witness cavity is from the same batch, is subjected to the same mold temperature, and experiences the same heat history as the corresponding rubber compound in the mold 18 , the rubber compound of the witness cavity provides a good representation of curing behavior observed in the part itself.

In addition, note that more than one sensor 17 can be used to monitor the curing process of a single part. Moreover, in one embodiment of such a multi-sensor 17 configuration of the present invention, the sensor 17 whose impedance data lags the corresponding impedance data from another of the sensors 17 can be used to control the end point of any given cure cycle.

(2.2) Sensor Measurement Unit 60 (Non-Bridged)

Electrical circuits described in the prior art typically include the use of bridge circuits, which are often complex and poorly suited for automation and/or mass production of rubber based parts. Moreover, such bridge circuits typically require an operator to manually balance the bridge, as one skilled in the art will understand.

The sensor measurement unit 60 (FIGS. 3, 6 and 13 ) for the present invention includes a simple voltage divider (FIG. 3) that, in turn, includes the resistor 19 and the complex voltage measurement and demodulation unit 25 . The sensor measurement unit is operatively connected to the capacitor 68 formed by sensor 17 and curing rubber 68 for both providing electrical current to the capacitor, and detecting impedance values resulting from the capacitor's response to the electrical signals. Note that the combination of the sensor measurement unit 60 and the capacitor 68 forms an impedance sensor circuit 62 . The current provided to sensor circuit 62 is driven to the electrical ground 25 of the mold 18 (via the opposing capacitor plate 64 described hereinabove) through the curing (polymeric) rubber compound 16 . The load resistor 19 (typically, having approximately a 200k-ohm resistance, although a range can be anywhere from 1 kOhm to several Mohms) is placed in line with the flow of current to the sensor 17 . The resultant voltage V 2 on circuit line 20 (FIG. 6) output by the amplifier 36 measures the voltage across the resistor 19 . By simultaneously measuring the applied voltage at position 21 (this applied voltage also known as the “excitation voltage”, and also referred to as “V 0 ”), the amount of attenuation and phase shift resultant from the flow of a complex current through the capacitor 68 is determined. FIG. 6 illustrates the sensor electrical circuit 60 , where the applied (excitation) voltage at position 21 (e.g., V 0 =sinωt) is placed at one terminal of the amplifier 36 , and this potential drives a complex current I* through the load resistor 19 (R) and then finally through the capacitor 68 formed by the sensor 17 , rubber compound 16 , and the electrical ground 25 attached to the mold 18 .

The following description assumes a voltage amplitude of 1 volt for the excitation V 0 at circuit position 21 . However, all the subsequent analysis remains the same if the voltage is not unity, in that for the non-unity cases, the constant “k” in the equations below is defined as the ratio of the negative voltage (V 1 ) at circuit position 22 to the positive voltage (V 0 ) at circuit position 21 .

The excitation voltage at position 21 (V 0 =sinωt) drives a complex current (I*) through the resistor 19 to ground 25 . Accordingly, the voltage V 0 is a digitally generated sine wave generated by a high-speed data acquisition card 35 (FIG. 13), such as the PCI-MIO-16E4 card manufactured by National Instruments of Austin, Tex. The data acquisition card 35 produces high quality sinusoidal signals at frequencies varying from 10 Hz to 10 kHz as specified by a user; however, other data acquisition cards 35 are also within the scope of the invention for generating similar or different ranges of frequencies such as the PCI-MIO-16E1 data acquisition card manufactured by National Instruments of Austin, Tex. which can generate and monitor frequencies from 10 Hz to 1.25 MHz. It is also within the scope of the invention to use a simultaneous sampling data acquisition card (e.g., a card specifically designed to carefully preserve interchannel phase relationships) such as the PCI-6110 card manufactured by National Instruments of Austin, Tex.

Upon application of the excitation voltage V 0 at circuit position 21 , there is a voltage drop that occurs across the load resistor 19 , leaving an attenuated and phase shifted signal at the circuit position 22 (i.e., V 1 =k sin(ωt+θ)=k<θ, where “<” is used to indicate a polar representation of a complex number and denotes the term “at a phase angle of”). The rubber compound 16 between the sensor 17 and electrical ground 25 provides a complex impedance of magnitude Z at phase angle Φ, wherein the phase angle Φ is a property of the curing rubber compound 16 , and is not to be confused with the phase angle θ, which is defined as the phase angle difference between V 0 and V 1 .

(2.3) Demodulation of the Sensor Signal.

Calculating Z and Φ is done by simultaneously digitally capturing the excitation signal V 0 (e.g., V0=sin(ωt)) and the amplifier 36 output voltage V 2 on circuit line 20 , where V 2 =sin(ωt)−k sin(ωt+θ). Alternately, in another embodiment of the invention, the same data could be obtained by capturing the sinusoids V 0 ((sin(ωt)) and V 1 (k sin(ωt+θ)) directly rather than capturing V 2 (sin(ωt)−k sin(ωt+θ)). Note that the previously referenced high-speed data acquisition card 35 can be used to digitize the signals V 0 at position 21 and the signals V 2 at position 20 thereby preserving the digital representation of the waveforms for further digital signal processing. Note that the values of Z and Φ obtained from the sensor measurement unit 60 as well as the various voltages (e.g., V 0 and V 2 , or alternatively, V 0 , V 1 and V 2 ) from which the values of Z and Φ are derived will hereinbelow be referred to “impedance signal data”.

Provided with the digitally preserved signals of V 0 and V 2 , measurement of the quantities k (attenuation) and θ (phase shift) is done via standard demodulation practices, as is understood by one skilled in the art.

Once the quantities k and θ have been measured, determination of Z and Φ is done by analyzing the circuit described in FIG. 6 as follows.

• • i. I*=(V 0 −V 1 )/R
  • ii. z=V 1 /I*
  • iii. Substituting, since V 1 =k<θ and V 0 =1
  • iv. Impedance (Z)*=R(k<θ)/(1−k<θ)=Z<Φ
  • v. As can be seen in the equation immediately above, the magnitude Z and phase angle are easily derived from the known values of R, k, and θ.
  • vi. Converting the polar number into a complex number separates out the real and imaginary components, series resistance and reactance.
  • vii. Series Reactance (Xs)=Z sinΦ=1/wC, where w=2πf
  • viii. Series Resistance (Rs)=Z cosΦ
  • ix. Series Capacitance (Cs)=1/wXs
  • x. Series Conductance (Gs)=1/Rs
  • xi. Rather than a series model, the impedance can also be modeled as a parallel combination of reactance (Xp) and resistance (Rp), as one skilled in the art will understand.
  • xii. Parallel Capacitance (Cp) can be calculated from the series reactance and resistance as follows: Cp=−X _S /[w(R _S ² +X _S ² )]
  • xiii. Parallel Resistance (Rp) can be calculated as follows: R _P =−X _S /wC _P R _S
  • xiv. Parallel Reactance (Xp) can be calculated as follows: X _P =−1/wC
  • xv. Parallel Conductance (Gp)=1/Rp.

In various embodiments of the invention, any time series of data pairs: (Z and Φ), (Rp and Xp), (Gp and Cp), (Xs and Rs) or (Gs and Cs) can be used to represent the resultant cure data (also referred to as “process curves” or equivalently impedance data streams).

In this document, reference to capacitance (C), conductance (G), reactance (X) or resistance (R) is generally made irrespective of the type of model selected (e.g., a series model, or a parallel model as described above). The impedance analysis performed by the present invention is the same regardless of which model is selected for use. That is, generic references to C, G, R, and X apply equally to either parallel or series data.

FIG. 7 shows a typical set of capacitance (C) data collected from a rubber compound cure process according to the present invention, wherein the data collected is displayed at 4 different excitation frequencies from 3 kHz to 9 kHz. FIG. 8 shows a typical set of conductance (G) data collected from the same rubber compound cure, wherein the data collected is again displayed for 4 different excitation frequencies from 3 kHz to 9 kHz.

(2.4) Method for Establishing Control Algorithms and/or Formulas

Given that impedance property data, i.e., (Z and Φ), (R and X), and/or (G and C), is capable of being observed and recorded during a rubber compound 16 curing process (e.g., as depicted in FIGS. 7 and 8), the present invention provides a control method for:

• • (a) measuring such impedance property data directly in the mass production process of cured rubber compound based parts, and
  • (b) reaching a conclusion with respect to proper cure time for a particular production cycle (i.e., the part(s) being currently cured), based on the data measurement from the capacitor 68 .

The process for algorithm or formula development is outlined below.

(2.4.1) Embodiment for Algorithm Development Using a Production Mold and a Rheometer

The following steps of FIG. 12 may be performed when a rheometer is available for used in conjunction with the mold 18 :

• • (Step 23 ) Identify the application of interest (type of part, type of polymeric rubber compound 16 to be used, and the desired characteristics of the parts to be produced, e.g., compression set, modulus, porosity, solvent swell, differential scanning calorimetry, maximum elongation, enlongation at break, dynamic spring rate, face load, as one skilled in the art will understand).
  • (Step 24 ) Install at least one sensor 17 in each production mold 18 , so that it can be used to obtain impedance property data on the curing rubber compound 16 .
  • (Step 26 ) Determine a plurality of curing conditions for producing the desired part, wherein each curing condition identifies one or more important cure parameters and a corresponding value or range for each such parameter. In one embodiment of the invention, curing conditions for two such parameters are determined, e.g., mold temperatures ranges, and rubber compound 16 batch identifiers. Note that the curing conditions may be determined by performing a statistically designed experiment, wherein each curing condition: (i) includes, for at least one parameter that substantially affects the curing process, a corresponding range of variation expected to occur within the normal production curing processes of the rubber compound 16 , and (ii) for each such parameter, a particular range of variation that is considered at least possible (if not likely) to occur during the curing of one or more of the rubber compound produced parts.
    • For example, the variations expected to occur within the normal curing production process includes changes in the composition of the rubber compound 16 being provided to the mold 18 . In particular, such rubber compound 16 composition changes typically correspond to changes in the batch of the rubber compound 16 being provided to the molds 18 . Thus, unique batch identifiers are used to identify (possibly) different compositions of the rubber compound 16 being used, and which may have different curing characteristics thereby requiring a different a cure time to reach an optimal or desired cure state. Similarly, for mold 18 temperature, the expected variations include, e.g., a +/−5 degree F. change in mold temperature, which could necessitate a different cure time to reach the desired cure state.
    • Each row of TABLE A following is illustrative of a typical or expected curing condition that may likely occur, wherein the term “normal”°in the mold temperature column of TABLE A is a predetermined temperature that is believed to be at least an acceptable curing temperature, and likely a preferred curing temperature. Accordingly, for each table row, by curing one or more rubber compound 16 samples according to the curing condition specified in the row, cure data can be obtained (which may be considered as calibration data in that this data becomes reference data to which various correlations are performed), wherein (as described hereinbelow) a first portion of this cure data includes impedance signal data (e.g., Z, Φ, R, X, G or C values) obtained from the capacitor(s) 68 , and a second portion that includes curing related data obtained from samples cured in a rheometer, wherein such curing related data (also referred to as rheometric data) includes one or more curing times for curing a sample to corresponding cure states indicative of, e.g., a particular elasticity, and/or a particular compression set property.

TABLE A
Case number	Mold temperature	Batch number
01	5 F. below nominal	Batch A
02	5 F. below nominal	Batch B
03	5 F. below nominal	Batch C
04	nominal	Batch A
05	nominal	Batch B
06	nominal	Batch C
07	5 F. above nominal	Batch A
08	5 F. above nominal	Batch B
09	5 F. above nominal	Batch C

• • (Step 27 ) Assuming that a plurality of curing conditions have been defined as in TABLE A above, the above-mentioned rheometric data can be collected using a rheometer (not shown) in a more controlled environment than that provided for mass part production using a mold 18 . In particular, each of the in-mold curing conditions can be simulated with a corresponding rubber compound 16 sample in a rheometer with the appropriate environmental curing conditions provided, thereby obtaining various types of rheometric data for the curing condition.
    • As will be described further hereinbelow, such rheometric data is used in combination with impedance related data (e.g., obtained from the first portion of the cure data that is, in turn, obtained from the curing of in-mold test samples) to determine cure prediction data, wherein such cure prediction data is for predicting: (i) an in-mold cure time for a desired likely or default cure state, and/or (ii) an in-mold relative rate of cure. In particular, for dominant environmental curing factors such as temperature, a likely or predicted cure time and/or rate of cure can be determined for each of a plurality of mold 18 temperatures, wherein such cure prediction data can be effectively used in predicting a cure time/rate of parts made from various rubber compound batches. For example, it is an aspect of the invention that such cure prediction data can be used not only for providing cure predictions for curing parts made from the rubber compound batches used in obtaining the prediction data, but additionally, the prediction data can be used for providing cure predictions for curing parts made from rubber compound batches not used in obtaining the prediction data.
    • In one embodiment of the invention, the rheometric data includes, what is known in the art as, the “T90 time” for each rubber compound sample cured in the rheometer, wherein the T90 time is the time that the curing rubber compound 16 reaches 90% of its desired final elastic torque maximum. However, it is within the scope of the invention to provide other cure state times in the rheometric data. For example, as one skilled in the art will understand after reviewing all the steps of FIG. 12, the following cure times may also be used: (a) T50 time for curing the rubber compound 16 to 50% of its desired final elastic torque maximum, (b) T75 time for curing the rubber compound 16 to 75% of its desired final elastic torque maximum, and/or (c) other times related to the rubber compound's desired final elastic torque, or related to tensile strength, spring constant, compression set, or dynamic stiffness.
    • So for each of the curing conditions (i.e., rows) described in Table A above, a rheometer may be set to the specified temperature, with a sample for the specified rubber compound 16 batch therein, for measuring, e.g., the T90 time. An illustrative example of the type of rheometric data collected by the present invention is as follows (TABLE B):

TABLE B
			Proper Cure
Case		Batch	time (T90:
number	Mold temperature	number	seconds)
01	5 F. below nominal	Batch A	120
02	5 F. below nominal	Batch B	135
03	5 F. below nominal	Batch C	142
04	nominal	Batch A	100
05	nominal	Batch B	110
06	nominal	Batch C	115
07	5 F. above nominal	Batch A	90
08	5 F. above nominal	Batch B	95
09	5 F. above nominal	Batch C	98

• • • Fundamentally, the purpose for the rheometric data is to establish relative rubber compound 16 cure rates and/or cure times that are likely to occur during, e.g., mass production of cured parts. Since in-mold conditions may vary significantly from rheometric instrument conditions, the optimum production cure time for a given part(s) may not be the same as the T90 time from the rheometer. However, the rheometric data does provide useful information regarding the relative cure rates and times observed due to the variation in both rubber compound 16 batch and cure temperature provided at the rheometer. In particular, for such rheometric data obtained from a sufficiently large number of samples (e.g., from a large number of both batches and curing temperatures), the rheometric data can be used for interpolating and/or extrapolating predictions of in-mold cure times/rates as will be described further hereinbelow.
  • (Step 28 ) In is step the effects of various curing conditions are determined by curing samples in the mold 18 . In particular, for each of the curing conditions (e.g., the rows of TABLE A), the curing condition is created at the mold 18 for curing a rubber compound sample. Accordingly, impedance signal data is obtained from the curing of each such in-mold sample. Examples of graphs of the impedance signal data that is captured from the in-mold curing of such samples is shown in FIGS. 7 and 8.
    • Multiple rubber compound samples are preferably cured for each in-mold curing condition, and more particularly, at least three such samples are cured per curing condition. For example, a production mold 18 can be set at a temperature 5 degrees below nominal, and batch A of a rubber compound 16 can be provided to this mold for obtaining impedance signal data during the curing of each of three rubber compound samples to the desired cure state (e.g., desired elasticity). Thus, once all the samples for batch A of the rubber compound 16 have been appropriately cured, the rubber compound 16 may then be changed to, e.g., batch B, and the impedance signal data for a plurality of batch B samples can be recorded. Accordingly, this process can be repeated until all designated rubber compound 16 batches have had samples therefrom cured, and accordingly an aggregate collection of impedance signal data is captured that is representative of the curing process for these batches. Note that although variations between rubber compound 16 batches are not, in general, believed to affect part curing as much as mold temperature, such variations can still impact the curing time and/or rate. However, by capturing impedance signal data as described here, most typical variations between rubber compound batches can be reflected in the aggregate collection. Thus, cure prediction data that is derived (in steps 29 and 30 hereinbelow) using this aggregate collection of impedance signal data is believed to be predictive of the in-mold curing time and/or rate substantially independently of what rubber compound batch is supplying the mold 18 with the rubber compound to be cured. That is, it is assumed that for a given type of rubber compound the variations between batches of the given type of rubber compound will not vary substantially from the batches used to determine the rheometric data, e.g., of TABLE B above. In particular, for each of the production parts cured in the mold 18 from a single type of a rubber compound, the actual instance or portion of a batch of this rubber compound is assumed to have each of its constituent ingredients in a range provided by some of the instances of the rubber compound obtained from the batches used to determine the rheometric data, e.g., of TABLE B above.
    • In one embodiment, at least three such rubber compound samples are cured in the mold 18 from each batch, wherein each of the three is cured at a different mold 18 temperature. In other embodiments, there may be additional samples cured. For example, there may be a plurality of samples cured according to the same curing conditions. In particular, for each rubber compound batch and each mold 18 temperature, there may be a plurality (e.g., 3) samples cured, and the impedance related data therefrom combined to obtain a composite for the impedance signal data resulting from the same signal frequency input to the capacitors 68 .
    • When all such simulations (i.e., sample curings) are complete for each mold 18 (and/or each distinct capacitor 68 in each mold), the impedance data obtained (likely in a distinct data file for each sample) will be associated with its corresponding curing condition as illustrated in Table C following.

TABLE C
			Proper
			Cure time	Associated
Case		Batch	(T90:	impedance
number	Mold temperature	number	seconds)	files
01	5 F. below nominal	Batch A	120	01, 02, 03
02	5 F. below nominal	Batch B	135	04, 05, 06
03	5 F. below nominal	Batch C	142	07, 08, 09
04	Nominal	Batch A	100	10, 11, 12
05	Nominal	Batch B	110	13, 14, 15
06	Nominal	Batch C	115	16, 17, 18
07	5 F. above nominal	Batch A	90	19, 20, 21
08	5 F. above nominal	Batch B	95	22, 23, 24
09	5 F. above nominal	Batch C	98	25, 26, 27

• • • Note that for simplicity of the remaining description, it will be assumed that there is a single mold 18 and a single capacitor 68 in the mold unless stated explicitly otherwise. One of ordinary skill in the art will readily understand how to apply the invention to a plurality of molds 18 and/or a plurality of capacitors 68 within a single mold 18 . For example, the invention can be applied to each mold 18 as if this mold were the only mold. Moreover, the invention can be applied to each of a plurality of capacitors 68 within a single mold 18 as if each such capacitor were the only capacitor, except that a curing time resolving component or task may be required to resolve cure time discrepancies between the outputs from multiple capacitors within the same mold 18 . Note, that one such resolving component can be described as follows: in the event that multiple sensors are used in a mold, lag logic may be applied to ensure that the mold is not opened until the longest predicted cure t