Patent ID: 12239891

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to golf club heads, and particularly iron-type golf club heads, which include a novel fill material comprising a polymeric material and a plurality of microscopic bubbles made of glass, ceramic, and/or plastic, also referred to herein as microscopic, hollow beads. The microscopic bubbles serve two purposes when incorporated with a polymeric material: (1) they lighten the overall fill weight by replacing elastomer with air, thus lowering the material's specific gravity; and (2) they increase the porosity of the fill material, allowing for the formation of micro-holes in the polymeric material. The micro-holes are little air pockets that allow the polymer to flex when the club head impacts a golf ball, thus increasing the COR of the head while at the same time maintaining the sound improvement provided by the polymer itself, such as reduction in dB level and duration. The polymeric material preferably is an elastomer such as polyurethane or silicone having a Poisson's ratio of 0.00-0.50, and more preferably 0.40-0.50, and the microscopic bubbles preferably are measured in D50 micron, which is the median particle size for a measured sample, each microscopic bubble having a diameter of approximately 18-50 microns.

A first embodiment of the golf club head is shown inFIGS.1and2. In this embodiment, the golf club head10is a cavity back iron having a face cup20, a body30, and a cavity40between the body and the striking portion22of the face cup. The cavity40is completely filled with the microscopic bubble fill material50, which does not extend into the upper cavity portion32of the body30.

In an alternative embodiment, shown inFIG.3, the golf club head10is a closed cavity back iron with a hollow interior15, which is completely filled with the microscopic bubble fill material50.

In yet another embodiment, shown inFIG.4, the golf club head10has an open cavity back35with a medallion60molded or otherwise formed from the microscopic bubble fill material50affixed to a rear surface23of the striking portion22. When the microscopic bubble fill material50is incorporated into a medallion60, it is preferably placed onto a back side of an electroformed medallion and permitted to cure, and then an adhesive is placed on the fill material and used to bond the medallion60onto the club head10.

In each of the embodiments disclosed herein, the microscopic bubbles in the novel fill material50preferably constitute 5% to 70% by volume of the fill material50, more preferably at least 20% of the volume, and most preferably approximately 25-30% of the fill material's 50 volume.

There are several methods of manufacturing the microscopic bubble fill material50and incorporating it into the golf club head10according to the present invention. The first method100, shown inFIG.5, comprises the steps of providing an elastomer material110such as polyurethane, providing microscopic bubbles120, combining the microscopic bubbles with the elastomer material130so that the microscopic bubbles form 5-70% of the volume of the resulting mixture, and more preferably approximately 25-30% of the volume of the resulting material, injecting the resulting mixture into a cavity40or hollow interior15of the golf club head, or a mold for a medallion140, and then oven curing the mixture or otherwise allowing it to cure150(e.g., at air temperature for self-curing materials).

The second, preferred method200, shown inFIG.6, comprises the steps of providing a pre-polymer resin (Part A)210such as a polyurethane or silicone, providing a curing or catalyst agent (Part B)220, and providing the microscopic bubbles230, combining the curing or catalyst agent (Part B) with the microscopic bubbles to form an intermediary material (Part C)240that is 5-70% by volume of microscopic bubbles, and more preferably 25-30% by volume, combining the intermediary material (Part C) with the polymer resin (Part A)250, preferably in a 1:1 Part A to Part B ratio, to form a final mixture, injecting the final mixture into a cavity40or hollow interior15of the golf club head, or a mold for a medallion260, and then oven curing the mixture or otherwise allowing it to cure270. The benefit of this method200is that the intermediary material (Part C) can be prepared and placed into storage until a manufacturer is ready to catalyze the pre-polymer resin.

The third method of the present invention is shown inFIG.7. This method300comprises the steps of providing a pre-polymer resin (Part A)310(preferably polyurethane or silicone), providing a curing or catalyst agent (Part B)320, and providing the microscopic bubbles330, combining the polymer resin (Part A) with the curing or catalyst agent (Part B)340, preferably in a 1:1 Part A to Part B ratio, to form an intermediary material, combining the intermediary material with microscopic bubbles350so that the microscopic bubbles are 5-70% of the volume of the resulting material, and more preferably 25-30% of the volume, injecting the resulting material into a cavity40or hollow interior15of the golf club head, or a mold for a medallion360, and then oven curing the mixture or otherwise allowing it to cure370.

In order to assess the COR performance of the inventive material, test iron-type golf club heads10having unfilled (empty) cavities were created and tested, and compared against golf club heads10having the same construction and filled with (1) the novel microscopic bubble fill material50comprising polyurethane and glass bubbles and made using one of the second200and third methods300and (2) polyurethane only. As shown in Tables 1 and 2, the polyurethane-only fill significantly lowers the COR of the golf club head10. In contrast, when a golf club head cavity is filled with the microscopic bubble fill material50(glass) of the present invention, the COR decreases, on average, only by 0.04, thereby retaining the performance benefits of an unfilled golf club head10. This is particularly evident when the microscopic bubbles or hollow microscopic beads constitute approximately 25% or 30% of the volume of the fill material50, as shown in Table 1.

TABLE 1Test Club No.COR (no fill)COR (polyurethane only)Change in COR1.0.8270.806−0.0212.0.8270.806−0.0213.0.8240.812−0.0124.0.8180.796−0.0225.0.8130.793−0.020Average change in COR−0.019Test Club No.COR (no fill)COR (30% glass bubble fill)6.0.8250.820−0.0057.0.8230.818−0.0058.0.8260.821−0.0059.0.8250.821−0.00410.0.8260.823−0.00311.0.8250.823−0.00212.0.8230.817−0.00613.0.8210.817−0.00414.0.8180.816−0.00215.0.8160.813−0.00316.0.8250.821−0.00417.0.8250.817−0.008Test Club No.COR (no fill)COR (25% glass bubble fill)18.0.8240.821−0.00321.0.8230.817−0.006Average change in COR−0.004

TABLE 2Test Club No.COR (no fill)COR (polyurethane only)Change in COR1.0.8130.793−0.20Test Club No.COR (no fill)COR (5% glass bubble fill)Change in COR2.0.8150.804−0.11

In order to assess sound performance, another group of test golf club heads10incorporating the 30% by volume novel microscopic bubble fill material50comprising polyurethane and glass bubbles, and made using one of the second200and third methods300were tested and compared with golf club heads10having: (1) the same construction and filled with only polyurethane; (2) no polyurethane filler at all; and (3) a small polyurethane snubber insert. As shown inFIGS.8and9, the 30% by volume microscopic bubble fill material50improves the pitch and amplitude of the golf club head10upon impact with a golf ball compared to a polyurethane-only fill, thereby improving the overall sound of the golf club head10. Preferably, a golf club head10incorporating the novel fill material has a pitch upon impact with a golf ball of 3000-6000 Hz, and more preferably of 4500-6000 Hz, an amplitude of 90-100 dB, and a duration of 1.0-2.5 ms.

To assess the effects of the novel fill material on ball speed performance, the performance of a Callaway Golf Apex CF 16 6-iron comprising a small polymeric snubber was compared with the performance of test 6-irons having no fill, test 6-irons with a fill having 30% by volume microscopic bubbles (glass material), and test 6-irons with a fill having 20% by volume microscopic bubbles (glass material). As shown inFIGS.10and11, the test irons comprising the novel, microscopic bubble fill had a higher median ball speed measured at both the center and low center of the striking face compared with the Apex CF 16 6-iron, and approached or surpassed the ball speed of test clubs lacking a fill material.

In yet another embodiment of the present invention, shown inFIGS.12and13, the golf club head10has many of the same features as the embodiments shown inFIGS.1-3, except that the cavity40extends further into a rear portion35of the body30of the golf club head10, and the golf club head10includes a weight70sized to fit within at least a portion of the cavity40. The weight70, which preferably is composed of a metal alloy material having a density of 4 g/cc or greater, such as steel or tungsten alloy, is over-molded with the novel fill material50of the present invention, which preferably completely envelops the weight70and at least partially fills the cavity40of the golf club head10. This embodiment serves to move mass downwards and towards the striking portion22of the face cup20without compromising the COR of the golf club head10.

The embodiment shown inFIGS.12-13can be achieved via several methods. A first method400, shown inFIG.14, comprises the steps of providing a golf club head comprising a body having a cavity410, providing a metal weight420, providing a fill material comprising a polymer material and a plurality of microscopic bubbles composed of a low-density material430, injection-molding the fill material onto the metal weight to create a co-molded weight440, and inserting the co-molded weight into the cavity450. An alternative method500, shown inFIG.15, comprises the steps of providing a golf club head comprising a body having a cavity510, providing a metal weight520, providing a fill material50comprising a polymer material and a plurality of microscopic bubbles composed of a low-density material530, inserting the metal weight into the cavity540, and injection-molding the fill material into the cavity and around at least a portion of the metal weight550. Each of these methods produces a golf club head having a low center of gravity and an optimized COR.

In a preferred embodiment, shown inFIGS.16-17, the face portion26of the face cup20has a variable thickness, with the striking portion22being planar and the rear surface23having a topography reflecting the variable thickness pattern. The variable thickness pattern improves the striking performance of the face cup20, but complicates the process of adding a medallion60to the rear surface23. As shown inFIGS.16and17, the golf club head comprises a thin layer of the fill material50coating the rear surface23, which creates a flat or planar surface80. The medallion60is then affixed to the planar surface80with an adhesive material65. The embodiment shown inFIGS.16-17also includes a weight70, which is enveloped in a first overmold material75and is secured within the cavity40with the fill material50of the present invention. This feature may be provided using the method illustrated inFIG.15.

A method of manufacturing the preferred embodiment is illustrated inFIG.18. This method600includes a first step610of providing a golf club face component or face cup20having a variable thickness striking portion22with a rear surface23topography; a second step620of injecting the fill material50onto the rear surface23of the striking portion22to form a flat, planar surface80, and a third step630of affixing a medallion60to the planar surface80630. The second step620preferably is performed when the face cup20is oriented so that the striking portion22is parallel with a ground plane, which is illustrated inFIG.18as step number615. In this orientation, the fill material50free flows onto the rear surface23and becomes self-leveling until the fill material50reaches its gel state.

From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.