DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Referring first to FIG. 1 , an iron clubhead 10 constructed in accordance with a preferred embodiment of this invention is shown and includes a body 12 having hosel portion 14 , heel portion 16 , toe portion 18 , upper edge 20 and lower edge 22 . As shown best in FIGS. 1, 2 and 3 , clubhead body 12 includes front portion 24 with cavity 26 , and a back portion 25 having an aperture 28 therein. In FIG. 1 , the cavity 26 receives a strike face insert 34 , dampening insert 36 in back of the strike face insert 34 and a composite back insert 38 supporting the dampening insert 36 . The aperture 28 allows for the viewing of the composite back insert 38 .

[0023] Strike face insert 34 is preferably made from stainless steel, although the skilled artisan will recognize that other suitable materials, such as titanium, brass and carbon steel (having sufficient strength characteristics and a strength to weight ratio), may be substituted without deviating from the scope of the invention. Strike face insert 34 is preferably coldworked into cavity 26 and includes conventional grooves 38 on a front surface thereof. Undercuts (not detailed herein) may be provided along the peripheral edge of cavity 26 for holding the inserts 34 , 36 and 38 in place as shown in FIG. 3 . The strike face insert 34 has a thickness (t ₁ ) that is preferably in the range between about 0.07 inches to about 0.11 inches, and more preferably about 0.09 inches.

[0024] Placed into the cavity 26 , in back of the strike face insert 34 is the vibration dampening insert 36 , formed preferably of lead which dissipates the vibration energy effectively enough to minimize resonance and propagation of vibrations, as well as to reduce acoustic noises. Dampening insert 36 preferably has a thickness (t ₂ ) that is in the range between about 0.005 inches to about 0.025 inches, and more preferably is about 0.01 inches. Lead, being very moldable under pressure, fills all voids behind the strike face insert 34 and between the body 12 . The dampening insert 36 , being made of lead, provides for a measure of “feel” which is so highly desired by golfers of all skill levels. The skilled artisan will readily recognize that many different shock absorbing materials may be substituted without deviating from the scope of the invention. Other suitable materials for dampening insert 36 in accordance with the present invention includes without limitation viscoelastic elastomers; vinyl copolymers with or without inorganic fillers; polyvinyl acetate with or without mineral fillers such as barium sulfate; acrylics; polyesters; polyurethanes; polyethers; polyamides; polybutadienes; polystyrenes; polyisoprenes; polyethylenes; polyolefins; styrene/isoprene block copolymers; metallized polyesters; metallized acrylics; epoxies; epoxy and graphite composites; natural and synthetic rubbers; piezoelectric ceramics; thermoset and thermoplastic rubbers; foamed polymers; ionomers; low-density fiber glass; bitumen; air bladders; liquid bladders; and mixtures thereof. The metallized polyesters and acrylics preferably comprise aluminum as the metal. Piezoelectric ceramics particularly allow for specific vibration frequencies to be targeted and selectively damped electronically. Commercially available dampening and acoustical materials applicable for the present invention include resilient polymeric materials such as Scotchdamp™ from 3M, Sorbothane®) from Sorbothane, Inc., DYAD® and GP® from Soundcoat Compancy Inc., Dynamat® from Dynamat Control of North America, Inc., NoViFlex™ Sylomer® from Pole Star Maritime Group, LLC, and Legetolex™ from Piqua Technologies, Inc.

[0025] Another group of suitable dampening and acoustical materials are low-density granular materials that when coupled to structures for the purpose of reducing structural vibrations, provide a concomitant attenuation in airborne acoustic noises radiated from the structure. Such low-density granular materials including without limitation perlite; vermiculite; polyethylene beads; glass microspheres; expanded polystyrene; nylon flock; ceramics; polymeric elastomers; rubbers; dendritic particles; and mixtures thereof. Low-density granular materials with dendritic structures and low bulk sound speeds are used to maximize damping of low-frequency vibrations and attenuating acoustic noises in club heads. Technology associated with the use of these low-density granular materials for damping structural vibrations is described by the trademark name Lodengraf™. Other low-density granular materials and their applications in various dampening acoustical systems are described in U.S. Pat. Nos. 5,924,261, 6,224,341, and 6,237,302, the disclosures of which are incorporated herein by reference in their entirety.

[0026] As previously stated, a back insert 38 , preferably made of carbon graphite material, is pressed into the cavity 26 , just in back of the dampening insert 36 . This back insert 38 will prevent the dampening material from “squeezing” out, and will provide a support for the malleable material. The thickness (t ₃ ) of the back sheet 38 is preferably in the range between about 0.02 inches to about 0.04 inches and more preferably about 0.03 inches. The aperture 28 , in the back of the body 12 , allows for the back insert 38 to be viewable as well as having material removed thereby increasing the perimeter weighing of the club head.

[0027] The cavity 26 is limited in depth and the three inserts 34 , 36 and 38 , may vary in thickness to achieve predetermined club characteristics. As an example, if the depth of the cavity 26 were approximately 0.14 inches and an embodiment had a thickness of 0.095 inches for the face insert 34, 0.005 inches for the dampening insert 36 and 0.04 inches for the back insert 38 , then an increase in the thickness of one insert would mean a decrease in thickness for at least one other. An increase in the thickness of the heavy weighted lead dampening insert 36 would make for a heavier club head and vice versa for a reduction in the thickness of the dampening insert 36 .

[0028] The reduction of vibration and refinement of acoustics provides the club 10 of the present invention, with playing qualities that approach those achieved with forged clubs, but with a much larger “sweet spot” than is available with forged clubs.

[0029] In an embodiment of the invention, a set of iron golf club heads of the invention is either a set of eleven iron club heads including the 1st to 9th irons, a pitching wedge and a sand wedge, or a set of plural iron club heads excluding some therefrom. All of these golf club heads are not shown in the drawings. A 2 iron, 6 iron and pitching wedge are selected to show the inventive concept, which is best illustrated in FIGS. 4 a to 4 b and 5 a to 5 b . Typically, in a set of iron golf clubs, the 1, 2, 3 and 4 irons are considered “long” irons, the 5, 6 and 7 are considered intermediate irons and the 8, 9 and wedges are referred to as “short” irons. As the numerical sequence of the irons goes up, the length of their shafts get progressively shorter. Drawings 4 a - 4 c depict the dimensional concept wherein the location of the heavier weighted dampening insert 36 is positioned higher to achieve a higher center of gravity in the higher numerically sequenced irons. In FIG. 4 a , the dampening insert 36 is at a relatively low position for the 2 iron head, thereby giving it a higher launch projectory. In FIG. 4 b , in the iron head depicting a 6 iron, the dampening insert 36 is about at the midpoint between the lower edge 22 and the upper edge 20 thereby raising the specific gravity for a lower projectory and therein giving the golfer an added measure of control over the shot. In FIG. 4 c , the dampening insert 36 is yet still at a point further away from the lower edge 22 thereby providing the short wedge iron with a high center of gravity for better shot control. As previously stated, as a club sequence number gets progressively higher, the shaft becomes shorter and is accompanied by an increasing weight of the head. Further, the larger a club number becomes, the larger a loft angle or an angle of the front portion 24 to a vertical plane becomes. Furthermore, the larger a club number becomes, the larger a lie angle or an angle of the shaft to a horizontal plane becomes as well.

[0030] In general, longer irons require longer travelling distances of balls than shorter irons. In other words, the smaller the number of an iron club, the longer travelling distance it requires. Manipulating the club head center of gravity locations creates an impulse vector that has an upward directed vertical component in the long irons therein increasing the club's ability for getting the ball airborne. The high numbered club irons, having large lofts, provide no problem in getting the ball airborne and, in fact, extremely high ball trajectories can adversely affect hitting accuracy for these irons. This tendency for high ball trajectories is reduced with higher centers of gravity for the club head.

[0031] In the embodiment depicted in FIGS. 5 a , 5 b and 5 c , the same principle of weight distribution and gradual elevation of the center of gravity as previously illustrated in FIGS. 4 a - 4 b is utilized, but with a geometric scheme more like the preferred embodiment shown in FIGS. 1 to 3 . This embodiment shifts the specific gravity of the iron head by coordinating the weight ratio between the dampening insert 36 and the back insert 38 .

[0032] Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.