US20130225320A1 - Golf club heads with improved sound characteristics - Google Patents

Golf club heads with improved sound characteristics Download PDF

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Publication number
US20130225320A1
US20130225320A1 US13/842,011 US201313842011A US2013225320A1 US 20130225320 A1 US20130225320 A1 US 20130225320A1 US 201313842011 A US201313842011 A US 201313842011A US 2013225320 A1 US2013225320 A1 US 2013225320A1
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United States
Prior art keywords
face
portion
club head
golf club
less
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Abandoned
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US13/842,011
Inventor
Brandon H. Woolley
Bing-Ling Chao
Todd P. Beach
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TaylorMade Golf Co Inc
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TaylorMade Golf Co Inc
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Priority to US201061428547P priority Critical
Priority to US13/331,798 priority patent/US20130017904A1/en
Application filed by TaylorMade Golf Co Inc filed Critical TaylorMade Golf Co Inc
Priority to US13/842,011 priority patent/US20130225320A1/en
Assigned to TAYLOR MADE GOLF COMPANY, INC. reassignment TAYLOR MADE GOLF COMPANY, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BEACH, TODD P., CHAO, BING-LING, WOOLLEY, BRANDON H.
Publication of US20130225320A1 publication Critical patent/US20130225320A1/en
Application status is Abandoned legal-status Critical

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    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B53/0466Heads wood-type
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B53/047Heads iron-type
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B2053/0408Heads with defined dimensions
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B2053/0416Heads with an impact surface provided by a face insert
    • A63B2053/042Heads with an impact surface provided by a face insert the face insert consisting of a material different from that of the head
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B2053/0416Heads with an impact surface provided by a face insert
    • A63B2053/042Heads with an impact surface provided by a face insert the face insert consisting of a material different from that of the head
    • A63B2053/0425Heads with an impact surface provided by a face insert the face insert consisting of a material different from that of the head the face insert comprising two or more different materials
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B2053/0433Heads with special sole configurations
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00Golf clubs
    • A63B53/04Heads
    • A63B2053/0458Heads with non-uniform thickness of the impact face plate
    • A63B2053/0462Heads with non-uniform thickness of the impact face plate characterised by tapering thickness of the impact face plate
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2209/00Characteristics of used materials
    • AHUMAN NECESSITIES
    • A63SPORTS; GAMES; AMUSEMENTS
    • A63BAPPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2209/00Characteristics of used materials
    • A63B2209/02Characteristics of used materials with reinforcing fibres, e.g. carbon, polyamide fibres

Abstract

Golf club heads with improved sound can be provided while implementing an adjustable loft, lie, and face angle adjustment system. A face portion is attached to the front portion of the golf club head. A sleeve is received in the hosel portion having a sleeve bore, a threaded portion, and an anti-rotation portion. A screw inserted into a sole opening in the sole portion configured to engage the threaded portion of the sleeve.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application claims the benefit of U.S. Provisional Application No. 61/428,547 and is a continuation-in-part of U.S. patent application Ser. No. 13/331,798, which is incorporated herein by reference in its entirety.
  • The following disclosure is provided with reference to U.S. patent application Ser. Nos. 11/960,609 11/642,310, 11/825,138, 11/998,436, 11/823,638, 12/004,386, 12,004,387, 11/960,610, 12/156,947, 12/462,198, 11/895,195 and U.S. Pat. Nos. 6,800,038, 6,824,475, 6,904,663, 6,997,820, 7,140,974, 6,811,496, 7,267,620 and 7,066,832 which are incorporated herein by reference in their entirety.
  • BACKGROUND
  • Golf clubs, especially wood type golf clubs such as driver, fairway woods, and hybrids can provide large “sweet spots” to reduce the ill effects of mishits. In addition, golf club makers provide such clubs with mass distributions that can tend to promote particular ball trajectories, and have preferred club head moments of inertia. Mass distribution in some such clubs can be readily adjusted by a golfer to promote a selected shot properties such as a fade or draw to compensate for individual swing characteristics.
  • Driver type golf clubs with large heads can provide golfers with enhanced confidence when they approach a shot. However, club manufactures have not recognized and addressed how club head sounds relate to golfer playing experience. Some large driver type club heads produce loud and unpleasant sounds when used to strike a ball. Some golf equipment reviewers have suggested that in some cases, a particular driver should come with earplugs. Thus, golf clubs, especially driver type golf clubs are needed that can provide superior sound characteristics.
  • SUMMARY
  • Methods comprise selecting a striking face material for a golf club head, and selecting a striking face area and thickness. A striking face acoustic mode frequency is determined, and based on the determined frequency, the striking face is adjusted. In some examples, the striking face is adjusted by varying a thickness or selecting a material having a different elastic constant or density. Typically, the club face is adjusted so that a lowest resonance frequency of the club face is greater than about 3.8 kHz, 4.0 kHz, 4.2 kHz, or 4.5 kHz. In other examples a sole acoustic mode or a crown acoustic mode at a frequency less than about 3.5 kHz is identified, and the sole or crown is adjusted so as to reduce an amplitude of the sole or crown acoustic mode when striking a golf ball. In some embodiments, a sole acoustic mode or a crown acoustic mode at a frequency less than about 2.5 kHz or 2.0 kHz is identified. In other examples, an A-weighted sound pressure or a sound level in response to a ball strike is determined. If the sound pressure or sound level exceeds a limit associated with a satisfactory sound, the club head is adjusted. In some examples, the limit is 225 sones or an A-weighted sound pressure of 5 Pa in response to a golf ball strike at a club head speed of about 110 mph. (As used herein, A-weighted sound pressures are at a distance of about 1 m). The “golf ball” used in all tests described herein is a TaylorMade® Tour Preferred® TP Red golf ball.
  • Driver type golf club heads include a club body configured to receive a striking plate and a composite striking plate configured to have a lowest order acoustic resonance frequency at a frequency of at least 3.8 kHz.
  • In one aspect of the invention, a golf club head is described having a body having a front portion, a crown portion, a sole portion, and a hosel portion. The body is comprised of a first material and a hosel bore is located in the hosel portion. A sleeve having a sleeve bore, a threaded portion, and an anti-rotation portion is received in the hosel portion. A screw engages the threaded portion of the sleeve. The screw is inserted into a sole opening in the sole portion. A first longitudinal axis is defined by the sleeve bore and a second longitudinal axis is defined by the hosel bore of the hosel portion. An offset angle is located between the first longitudinal axis and second longitudinal axis. The offset angle is between 0 degrees and 4 degrees. A face portion comprising a second material is attached to the front portion of the body, the face portion having a face size surface area being at least at least 4,500 mm2. A coefficient of restitution greater than 0.79 and a characteristic time greater than 220 μs is also disclosed. A loudness of the club head is less than 240 sones upon striking a golf ball at about 110 mph. The loudness is measured by a microphone positioned at 64 inches above the golf ball. The face portion has a characteristic time slope of greater than 10 and less than 150.
  • In another aspect of the invention, the second material is a composite material having a layup-to-fiber ratio of greater than 0.5 but less than 1.
  • In yet another aspect of the invention, the second material is a composite material having a strength-to-modulus fiber ratio of greater than 1 and less than 10. In addition, the second material is a composite material having a strength-to-modulus layup ratio of greater than 0.5 and less than 10.
  • In another aspect of the invention, the face portion includes a face insert and a recess that receives the face insert and defines a face insert depth. A rear support member is disclosed having an end point thickness. A face insert ratio between 0.5 and 10 is also disclosed. The face insert ratio is defined as the face insert depth divided by the end point thickness.
  • In yet another aspect of the invention, a peak un-weighted acoustic amplitude of the club head is less than 114 dB. A peak A-weighted sound pressure level of the club head is less than 5 Pa as measured by the microphone positioned at 64 inches above the golf ball. The face portion includes a face insert having a face insert area and a face insert area-to-face size ratio of greater than 0.65 and less than 1.
  • In one aspect of the invention, the golf club head further includes a maximum sound power-to-frequency ratio greater than 1*10−5 watts/hertz and less than 4.5*10−5 watts/hertz. The golf club has a head volume between 400 cc to about 475 cc and has a frequency-to-volume ratio of greater than 6.0 hertz/cc and less than 16 hertz/cc. The golf club head includes at least one movable weight.
  • In another aspect of the invention, the sole opening is located adjacent to a non-undercut portion. Furthermore, a heel-side rear support member is integral with an internal hosel tube structure.
  • Methods comprise determining an acoustic resonance frequency of a driver type golf club head sole, crown, or face, and evaluating the resonance frequency to determine if a club head is to be adjusted. Based on the evaluation, at least one of the following adjustments is performed: selecting a less dense material for a crown, sole, or face; altering a face thickness, thinning or thickening a club face at an antinode of the acoustic resonance. In some examples, an acoustic level associated with a club face/golf ball impact is determined, and the club head is adjusted based on the determination.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is an exploded view of a club head in accordance with the invention, depicting a composite face insert and a metallic body.
  • FIG. 2 is a cross-sectional view of the club head of FIG. 1.
  • FIG. 3 is an exploded view of the composite region of the face insert of FIG. 1 showing the plies comprising the composite region.
  • FIG. 4 is a close-up view of area A-A of the club head of FIG. 2, depicting a junction of the composite face insert and the body portion.
  • FIG. 5 is a graph depicting resin viscosity over time during the soaking and curing phases for a preferred method of forming the composite portion of the face insert of FIG. 1.
  • FIG. 6 is a graph depicting pressure over time during the soaking and curing phases of forming the composite portion of the face insert, corresponding to FIG. 5.
  • FIG. 7 is a graph depicting temperature over time during the soaking and curing phases of forming the composite portion of the insert, corresponding to FIG. 5.
  • FIG. 8 is a graph depicting pressure over time during the soaking and curing phases of an alternative method of forming the composite portion of the insert of FIG. 1.
  • FIG. 9 is a graph depicting temperature over time during the soaking and curing phases of forming the composite portion of the insert, corresponding to FIG. 8.
  • FIG. 10A illustrates a front view of an embodiment of a golf club head in an address position.
  • FIG. 10B illustrates a toe-side view of the golf club head shown in FIG. 10A.
  • FIG. 11 illustrates a cross-sectional side view of a golf club head taken through an ideal impact location, according to one embodiment.
  • FIG. 12 illustrates a cross-sectional side view of a golf club head taken through an ideal impact location, according to another embodiment.
  • FIG. 13A illustrates a cross-sectional side view of a golf club head taken through an ideal impact location, according to another embodiment.
  • FIG. 13B illustrates a detailed view of a lower leading edge zone.
  • FIG. 14A illustrates an adhesive interface between a face insert and club head body, according to one embodiment.
  • FIG. 14B illustrates an adhesive interface between a face insert and club head body, according to another embodiment.
  • FIG. 15A illustrates an engineering gap between a face insert and a club head body, according to another embodiment.
  • FIG. 15B illustrates a front view of the golf club head shown in FIG. 15A.
  • FIG. 16 illustrates a cross-sectional side view of a golf club head taken through an ideal impact location, according to another embodiment.
  • FIG. 17 illustrates a cross-sectional side view of a golf club head taken through an ideal impact location, according to another embodiment.
  • FIG. 18 illustrates a cross-sectional side view of a golf club head taken through an ideal impact location, according to another embodiment.
  • FIG. 19 illustrates a front view of a golf club head in an address position, according to another embodiment.
  • FIG. 20 is a representative method of evaluating and modifying golf club head acoustic characteristics.
  • FIG. 21A is a graph illustrating acoustic vibrational amplitude as a function of time and frequency subsequent to striking a golf ball for a representative club head (#2) having a composite striking plate.
  • FIG. 21B illustrates acoustic vibrational amplitude at a frequency of about 3.84 kHz that is associated with a striking plate acoustic mode. (Club head #2).
  • FIG. 22A is a graph illustrating acoustic vibrational amplitude as a function of time and frequency subsequent to striking a golf ball for a representative club head (#1) having a titanium alloy striking plate.
  • FIGS. 22B-22E provide additional data for club head #1. FIG. 22B illustrates acoustic vibrational amplitude at a frequency of about 3.13 kHz that is associated with a striking plate acoustic mode for the club head used to obtain the data of FIG. 22A.
  • FIG. 22C illustrates relative acoustic amplitude as a function of frequency when this club head is used by two players (referred to herein for convenience as “Player A” and “Player B”) to strike a golf ball with different swing speeds.
  • FIGS. 22D-22E are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for the two different players.
  • FIG. 23A is a graph illustrating acoustic vibrational amplitude as a function of time and frequency subsequent to striking a golf ball for a representative club head (#3) having a composite striking plate with a titanium cap.
  • FIGS. 23B-23D provide additional data for club head #3. FIG. 23B illustrates relative acoustic amplitude as a function of frequency associated with a club head having a Ti-capped composite striking surface for ball strikes by two players with different swing speeds.
  • FIGS. 23C-23D are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for ball strikes the two different players with the Ti-capped composite striking face.
  • FIG. 24A is a graph illustrating acoustic vibrational amplitude as a function of time and frequency subsequent to striking a golf ball for a representative club head (#4) having a titanium striking plate.
  • FIGS. 24B-24G provide additional data for club head #4. FIGS. 24B-24D illustrate acoustic vibrational amplitude at frequencies of about 1.84 kHz, 2.59 kHz, and 3.93 kHz, respectively, that are associated with a sole mode, a crown mode, and a striking plate mode, respectively.
  • FIG. 24E illustrates relative acoustic amplitude as a function of frequency associated with the club head used for FIG. 24A for ball strikes by two players with different swing speeds.
  • FIGS. 24F-24G are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for ball strikes by the two different players.
  • FIGS. 25A-25D are graphs illustrating acoustic vibrational amplitude as a function of time and frequency subsequent to striking a golf ball for a representative club head (#5) having a composite striking plate. FIG. 25B illustrates relative acoustic amplitude as a function of frequency associated with ball strikes by two players with different swing speeds. FIGS. 25C-25D are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for the two different players.
  • FIGS. 26-27 are graphs illustrating acoustic vibrational amplitude as a function of time and frequency subsequent to striking a golf ball for additional representative club heads (#6 and #7, respectively) having a composite striking plate.
  • FIGS. 28A-28B illustrate sound levels in sones and an A-weighted sound pressure, respectively, for a plurality of club heads, in response to ball strikes with a club head speed of about 110 mph.
  • FIG. 29 illustrates a chart comparing loudness and face size.
  • FIG. 30 illustrates a chart comparing face frequency and face size.
  • FIG. 31 illustrates a chart comparing peak un-weighted signal and face size.
  • FIG. 32 illustrates a chart comparing peak un-weighted signal and face frequency.
  • FIG. 33A illustrates a method of measuring face size.
  • FIG. 33B illustrates a method of measuring face size to exclude the hosel portion surface area.
  • FIG. 33C illustrates a face surface area projected onto a plane.
  • FIG. 34A illustrates a top view of a golf club head.
  • FIG. 34B is an elevated front view of the golf club head in FIG. 34A showing a golf club head origin coordinate system and a center of gravity according to one embodiment.
  • FIG. 34C is an elevated toe view of the golf club head in FIG. 34A.
  • FIG. 34D is an isometric sole view of the golf club head in FIG. 34A.
  • FIG. 34E is a cross-sectional view taken along section lines 34E-34E in FIG. 34B.
  • FIG. 35 is a cross-sectional view of an undercut and non-undercut structure taken along section lines 35-35 in FIG. 34A.
  • FIG. 36A illustrates an acoustic amplitude as a function of frequency associated with the club head described in FIGS. 34A-E and FIG. 35 for two different swing speeds.
  • FIG. 36B illustrates loudness (sones) as a function of time for the two different players.
  • FIG. 36C illustrates acoustic amplitude (dB) as function of time for the two different players.
  • FIG. 37 illustrates a detailed cross-sectional view of an undercut region.
  • FIG. 38 illustrates a sound power estimate of an exemplary embodiment.
  • FIG. 39 illustrates a sound power estimate of another exemplary embodiment.
  • FIG. 40 illustrates a characteristic time slope.
  • DETAILED DESCRIPTION
  • With reference to the illustrative drawings, and particularly FIGS. 1 and 2, there is shown a golf club head 10 having a metallic body 12 and a face insert 14 comprising a composite region 16 and a metallic cap 18. The face insert 14 is durable and yet lightweight. As a result, weight can be allocated to other areas of the club head 10, enabling the club head's center of gravity to be desirably located farther from the striking face 40 and to further enhance the club head's moment of inertia. The body 12 includes an annular ledge 32 for supporting the face insert 14. In a preferred embodiment, the body 12 is formed by investment casting a titanium alloy. With the face insert 14 in place, the club head 10 defines a volume of at least 200 cc and more preferably a volume of at least 300 cc. The volume described herein is measured according the USGA method of measuring head volume. The club head 10 has superior durability and club performance, including a coefficient of restitution (COR) of at least 0.79.
  • With reference to FIG. 3, the composite region 16 of the face insert 14 is configured to have a relatively consistent distribution of reinforcement fibers across a cross section of its thickness to facilitate efficient distribution of impact forces and overall durability. The composite region 16 includes prepreg plies, each ply having a fiber reinforcement and a resin matrix selected to contribute to the club's durability and overall performance. Tests have demonstrated that composite regions formed of prepreg plies having a relatively low fiber areal weight (FAW) provide superior attributes in several areas, such as, impact resistance, durability and overall club performance. More particularly, FAW values below 140 g/m2, 100 g/m2, or 70 g/m2 or 50 g/m2, are considered to be particularly effective. Several prepreg plies having a low FAW can be stacked and still have a relatively uniform distribution of fiber across the thickness of the stacked plies. In contrast, at comparable resin content (R/C) levels, stacked plies of prepreg materials having a higher FAW tend to have more significant resin rich regions, particularly at the interfaces of adjacent plies, than stacked plies of lower FAW materials. It is believed that resin rich regions tend to inhibit the efficacy of the fiber reinforcement, particularly since the force resulting from golf ball impact is generally transverse to the orientation of the fibers of the fiber reinforcement. Preferred methods of manufacturing, which aid in reducing resin rich regions, are discussed in detail further below.
  • Due to the efficiency of prepreg plies of low FAW, the face insert 14 can be relatively thin, less than about 10 mm, or less than about 4.5 mm, or less than about 3.5 mm. Thus, use of the face insert 14 results in weight savings of about 10 g to 15 g over a comparable volume of metal used in the body 12 (e.g., Ti-6Al-4V). As mentioned above, this weight can be allocated to other areas of the club, as desired. Moreover, the club head 10 has demonstrated both superior durability and performance. In a durability test, the club head 10 survived over 3000 impacts of a golf ball shot at a velocity of about 44 m/sec. In a performance test of the club's COR, measured in accordance with the United States Golf Association Rule 4-1a, the club head had a COR of about 0.828.
  • With continued reference to FIG. 3, each prepreg ply of the composite region 16 as a quasi-isotropic fiber reinforcement, and the plies are stacked in a prescribed order and orientation. For convenience of reference, the orientation of the plies is measured from a horizontal axis of the club head's face plane to a line aligned with the fiber orientation of each ply. A first ply 20 of the composite region 16 is oriented at 0 degrees, followed by ten to twelve groups of plies (22, 24, 26) each having four plies oriented at 0, +45, 90 and −45 degrees, respectively. Thereafter, a ply 28 oriented at 90 degrees precedes the final or innermost ply 30 oriented at 0 degrees. In this embodiment, the first and final plies are formed of a prepreg material reinforced by glass fibers, such as 1080 glass fibers. The remaining plies are formed of prepreg material reinforced by carbon fiber.
  • A suitable carbon fiber reinforcement comprises a carbon fiber known as “34-700” fiber, available from Grafil, Inc., of Sacramento, Calif., which has a tensile modulus of 234 GPa (34 Msi) and tensile strength of 4500 Mpa (650 Ksi). Another suitable fiber, also available from Grafil, Inc., is a carbon fiber known as “TR50S” fiber which has a tensile modulus of 240 GPa (35 Msi) and tensile strength of 4900 Mpa (710 Ksi). Suitable epoxy resins known as Newport 301 and 350 are available from Newport Adhesives & Composites, Inc., of Irvine, Calif.
  • In a preferred embodiment, the composite region 16 includes prepreg sheets having a quasi-isotropic fiber reinforcement of 34-700 fiber having an areal weight of about 70 g/m2 and impregnated with an epoxy resin (e.g., Newport 301) resulting in a resin content (R/C) of about 40%. For convenience of reference, the primary composition of a prepreg sheet can be specified in abbreviated form by identifying its fiber areal weight, type of fiber, e.g., 70 FAW 34-700. The abbreviated form can further identify the resin system and resin content, e.g., 70 FAW 34-700/301, R/C 40%. In a durability test, several plies of this material were configured in a composite region 16 having a thickness of about 3.7 mm. The resulting composite region 16 survived over 3000 impacts of a golf ball shot at a velocity of about 44 m/sec. In another preferred embodiment, the composite region 16 comprises prepreg plies of 50 FAW TR50S/350. This material was tested in a composite region 16 having a thickness of about 3.7 mm and it too survived a similar durability test.
  • With reference to FIG. 4, the face insert 14 has sufficient structural strength that excessive reinforcement along the interface of the body 12 and the face insert 14 is not required, which further enhances beneficial weight allocation effects. In this embodiment, the body 12 is formed of a titanium alloy, Ti-6Al-4V; however, other suitable material can be used. The face insert 14 is supported by an annular ledge 32 and is secured with an adhesive. The annular ledge 32 has a thickness of about 1.5 mm and extends inwardly between about 3 mm to about 6 mm. The annular ledge 32 is sufficiently recessed to allow the face insert 14 to sit generally flush with a transition edge 34 of the body. Although, in this embodiment, the annular ledge 32 extends around the periphery of the front opening, it will be appreciated that other embodiments can utilize a plurality of spaced annular ledges, e.g., a plurality of tabs, to support the face insert 14.
  • With continued reference to FIG. 4, the metallic cap 18 of the face insert 14 includes a rim 36 about the periphery of the composite region 16. In a preferred embodiment, the metallic cap 18 may be attached to a front surface of the face insert 14, wherein the combined thickness of the prepreg plies of the face insert 14 and the metallic cap 18 are no greater than the depth D of the annular ledge 32 at the front opening of the body 12. The rim 36 covers a side edge 38 of the composite region 16 to further protect against peeling and delamination of the plies. The rim 36 has a height substantially the same as the thickness of the face insert 14. In an alternative embodiment, the rim 36 may comprise a series of segments instead of a continuous cover over the side edge 38 of the composite region 16. The metallic cap 18 and rim 36 may be formed, for example, by stamping or other methods known to those skilled in the art. A preferred thickness of the metallic cap 18 is less than about 0.5 mm or less than about 0.3 mm. However, in embodiments having a face insert 14 without a metallic cap 18, weight savings of about 15 g can be realized.
  • In one embodiment, the thickness of the composite region 16 is about 4.5 mm or less and the thickness of the metallic cap 18 is about 0.5 mm or less. The thickness of the composite region 16 is about 3.5 mm or less and the thickness of the metallic cap 18 is about 0.3 mm or less. In some embodiments, the metallic cap comprises a titanium alloy.
  • Composite Material Process
  • The metallic cap 18 defines a striking face 40 having a plurality of grooves 42. The metallic cap 18 further aids in resisting wear from repeated impacts with golf balls even when covered with sand. A bond gap 44 of about 0.05 mm to 0.2 mm, or about 0.1 mm, is provided for adhesive attachment of the metallic cap 18 to the composite region 16. In an alternative embodiment, the bond gap 44 may be no greater than 0.2 mm. The metallic cap 18 is formed of Ti-6Al-4V titanium alloy; however, other titanium alloys or other materials having suitable characteristics can be employed. For example, a non-metallic cap, such as a cap comprising injection-molded plastic, having a density less than 5 g/cc and a hardness value of 80 Shore D may be employed.
  • As mentioned above, it is beneficial to have a composite region 16 that is relatively free of resin rich regions. To that end, fiber reinforcement sheets are impregnated with a controlled amount of resin to achieve a prescribed resin content. This is realized, in part, through management of the timing and environment in which the fiber sheets are cured and soaked.
  • The plies can be cut at least twice before achieving the desired dimensions. A preferred approach includes cutting plies to a first size, debulking the plies in two compression steps of about two minutes each. Thereafter, the plies are die cut to the desired shape, and compressed a third time; this time using a panel conformed to the desired bulge and roll. The plies are then stacked to a final thickness and compressed a fourth time with the conformed panel for about three minutes. The weight and thickness are measured preferably prior to the curing step.
  • The plies can be cut at least twice before achieving the desired dimensions. A preferred approach includes cutting plies to a first size and debulking the plies in two compression steps of about two minutes each. Thereafter, the plies are die cut to the desired shape, and compressed a third time using a panel conformed to the desired bulge and roll. The plies are then stacked to a final thickness and compressed a fourth time with the conformed panel for about three minutes. The weight and thickness of the plies are measured preferably prior to the curing step.
  • FIGS. 5-7 depict an effective soaking and curing profile for impregnating plies 70 FAW 34/700 fiber sheet with Newport 301 resin. Soaking and curing occurs in a tool having upper and lower plates. The tool is pre-layered with a mold release to facilitate removal of the composite material and is pre-heated to an initial temperature (T1) of about 200° F. The initial soak period is for about 5 minutes, from t0 to t1. During the soak phase, the temperature and pressure remain relatively constant. The pressure (P1) is at about 15 psi.
  • An alternative soaking and curing profile is depicted in FIGS. 8 and 9. In this process, the temperature of the tool is initially about 200° F. (T1) and upon placement of the composite material into the tool, the temperature is increased to about 270° F. (T2). The temperature is then kept constant. The initial pressure (P1) is about 20 psi. The initial soak period is for about 5 minutes, from t0 (0 sec.) to t′1. The pressure is then ramped up to about 200 psi (P2). The post cure phase lasts about 15 minutes (t′1 to t′2) and a final soaking/curing cycle is performed at a pressure (P1) of 20 psi for 20 minutes (t′2 to t′3).
  • Composite Face Roughness Treatment
  • In order to increase the surface roughness of the composite golf club face and to enhance bonding of adhesives used therewith, a layer of textured film can be placed on the material before curing. An example of the textured film is ordinary nylon fabric. Curing conditions do not degrade the fabric and an imprint of the fabric texture is transferred to the composite surface. Tests have shown that adhesion of urethane and epoxy, such as 3M® DP460, to the treated composite surface was greatly improved and superior to adhesion to a metallic surface, such as cast titanium alloy.
  • In order to increase the surface roughness of the composite region 16 and to enhance bonding of adhesives used therewith, a layer of textured film can be placed on the composite material before curing. An example of the textured film is ordinary nylon fabric. Curing conditions do not degrade the fabric and an imprint of the fabric texture is transferred to the composite surface. Tests have shown that adhesion of urethane and epoxy, such as 3M® DP460, to a composite surface treated in such a fashion was greatly improved and superior to adhesion to a metallic surface, such as cast titanium alloy.
  • A face insert 14 having increased surface roughness may comprise a layer of textured film co-cured with the plies of low FAW material, in which the layer of textured film forms a front surface of the face insert 14 instead of the metallic cap 18. The layer of textured film preferably comprises nylon fabric. Without the metallic cap 18, the mass of the face insert 14 is at least 15 grams less than a face insert of equivalent volume formed of the metallic material of the body 12 of the club head 10.
  • Typically, adhesion of the 3M® DP460 adhesive to a cast metallic surface is greater than to an untreated composite surface. Consequently, when the face structure fails on impact, the adhesive peels off the composite surface but remains bonded to the metallic surface. After treating a composite surface as described above, the situation is reversed [−] and the 3M® DP460 peels off the metallic surface but remains bonded to the composite surface.
  • The enhanced adhesion properties of this treatment contribute to an improved fatigue life for a composite golf club face. In a test, a club head having an untreated face insert 14 and a COR of about 0.847 endured about 250 test shots before significant degradation or failure occurred. In contrast, a similar club head having a treated face insert 14 and a COR of about 0.842 endured over 2000 shots before significant degradation or failure occurred.
  • Alternatively, the means for applying the composite texture improvement may be incorporated into the mold surface. By doing so, the textured area can be more precisely controlled. For simple face plate joining to the opening of a cast body, the texture can be formed in surfaces where shear and peel are the dominant modes of failure.
  • It should be appreciated from the foregoing that the present invention provides a club head 10 having a composite face insert (or face portion) 14 attached to a metallic body 12, forming a volume of at least 200 cc and providing superior durability and club performance. To that end, the face insert 14 comprises prepreg plies having a fiber areal weight (FAW) of less than 100 g/m2. The face insert 14 has a thickness less than 6 mm and has a mass at least 10 grams less than a face insert of equivalent volume formed of the metallic material of the body 12 of the club head 10. The coefficient of restitution for the club head 10 is at least 0.79.
  • Alternatively, the face insert 14 may comprise any non-metallic material having a density less than a metallic material of the body 12 along with a metallic cap 18 covering a front surface of the face insert 14 and having a rim 36. For example, the face insert 14 of the present invention may comprise a composite material, such as a fiber-reinforced plastic or a chopped-fiber compound (e.g., bulk molded compound or sheet molded compound), or an injection-molded polymer either alone or in combination with prepreg plies having low FAW. The thickness of the face insert 14 may be substantially constant or it may comprise a variation of at least two thicknesses, one being measured at a geometric center and another measured near a periphery of the face insert 14. In one embodiment, for example, an injection-molded polymer disk may be embedded in a central region of a plurality of low FAW prepreg plies. The total thickness of the face insert 14 may range between about 1 mm and about 8 mm, and between about 2 mm and about 7 mm, or between about 2.5 mm and about 4 mm, or between about 3 mm and about 4 mm.
  • In addition, the body 12 of a club head 10 in the present invention may be formed of a metallic material, a non-metallic material or a combination of materials, such as a steel skirt and sole with a composite crown, for example. Also, one or more weights may be located in or on the body 12, as desired, to achieve final performance characteristics for the club head 10.
  • FIG. 10A illustrates a hollow iron golf club head 1000 including a heel 1002, toe 1004, sole portion 1008, and top line portion 1006. The striking face 1010 includes scoreline grooves 1012 that are designed for impact with the golf ball. The scorelines described in the embodiments herein can be molded into a composite face insert. In some embodiments, the golf club head 1000 body can be a single unitary cast piece that is adhesively attached to a striking face 1010 that is formed separately. In certain embodiments, the striking face 1010 is a composite insert as will be described in further detail below.
  • FIGS. 10A and 10B also show a center point 1001 being an ideal striking point in the center of the striking face 1010 and respective orthogonal center of gravity (hereinafter, “CG”) axes. A CG x-axis 1005, CG y-axis 1007, and CG z-axis 1003 intersect at the center point 1001. In addition, a CG z-up axis 1009 is defined as an axis perpendicular to the ground plane 1011 and having an origin at the ground plane 1011. The ground plane 1011 is assumed to be a perfectly flat plane.
  • In certain embodiments, a desirable CG-x location is between about 5 mm (heel side) and about −5 mm (toe side) along the CG x-axis 1005. A desirable CG-y location is between about 5 mm to about 20 mm along the CG y-axis 1007 toward the rear portion of the club head. Additionally, a desirable CG-z location is between about 12 mm to about 25 mm along the CG z-up axis 1009, as previously described.
  • FIG. 10B illustrates an elevated toe view of the golf club head 1000 including a back portion 1028, a front portion 1030, a sole portion 1008, a top line portion 1006, and a striking face 1010, as previously described. The front surface of the striking face 1010 is contained within a face plane 1025.
  • FIG. 11 illustrates a cross-sectional view according to one exemplary embodiment. The club head 1100 includes a back portion 1106, a top line portion 1104, a front portion 1102 and a sole portion 1108. A composite striking face 1112 is located on the front portion 1102 of the body. In other words, the body includes a front opening that receives the composite striking face 1112. After adhesively attaching the composite face 1112, an interior cavity 1114 is formed. The club head 1100 back portion 1106 further includes a rear wall having an upper rear wall 1132 and a lower rear wall 1128, and a sound and vibration dampening badge 1130. The back portion 1106 also includes a rear protrusion 1124, an upper edge 1126, and a sole thickness 1122.
  • FIG. 11 further shows the front opening of the club head body having a ledge 1134 extending around an entire periphery of the front opening of the body. It is understood that the ledge 1134 can be continuous or intermittently located around a periphery of the front opening. In one embodiment, the ledge 1134 is perpendicular to a front opening wall 1136. In one embodiment, the ledge extends inwardly toward a center region of the face by a ledge distance 1118 of about 1 mm to about 5 mm, or about 3 mm to about 4 mm. Similarly, the front opening wall 1136 extends perpendicularly away from a plane of the striking face by a depth distance 1120 between about 1 mm to about 5 mm, or between 3 mm to about 4 mm.
  • In addition the striking insert 1112 includes a varying thickness and a thickened peripheral portion having a third thickness dimension 1110. The composite insert 1112 includes a first thickness 1111 at the thinnest region of the striking insert 1112 and a second thickness 1116 located in a central region of the striking insert 1112. The second thickness 1116 is the thickest dimension within the central region of the striking insert 1112. In one embodiment, the second thickness 1116 is greater than the first thickness 1111 and less than the third thickness 1110 of the peripheral portion. The third thickness 1110 located in a peripheral portion of the striking insert 1112 is greater than both the second thickness 1116 and the first thickness 1111. The peripheral region of the striking insert 1112 having the third thickness 1110 is attached to the ledge 1134.
  • In one embodiment, the first thickness 1111 can be between about 1.5 mm and about 2.0 mm, with a preferred thickness of about 2 mm or less. The second thickness 1116 can be between about 2 mm and about 3 mm and the third thickness 1110 is between about 3 mm and about 4.5 mm, or about 3.5 mm to about 4.0 mm.
  • Alternatively, variable thickness configurations or inverted cone configurations can be implemented in the striking face 1112 as discussed in U.S. Pat. Nos. 6,800,038, 6,824,475, 6,904,663, and 6,997,820, all incorporated herein by reference in their entirety.
  • In the examples described herein, a composite face insert can have a striking surface area in a range of about 2,700 mm2 to about 5,000 mm2. The unsupported surface area (surface area on the rear surface of the striking insert that is not engaged with a supporting surface) of the composite face insert can be within a range of about 300 mm2 to about 4,000 mm2, or 450 mm2 to about 3,500 mm2. In some embodiments, the unsupported surface area is at least greater than about 2,000 mm2. The unsupported surface area is the portion of the composite insert that is defined by the first thickness 1111 and second thickness 1116 excluding the peripheral portion. The composite face thickness can be within a range of about 1 mm to about 8.0 mm, or about 2.5 to about 6 mm. In certain embodiments, the composite face thickness is less than about 5.5 mm. In embodiments having a thickened region, the thickened region surface area can range from about 230 mm2 to about 2,000 mm2.
  • FIG. 12 illustrates an alternative embodiment of a golf club head 1200 including a front portion 1202, a rear portion 1206, a sole portion 1208 and a top line portion 1204. The club head 1200 includes a front opening located in the front portion 1202. The club head 1200 further includes a composite striking insert 1216, a gap cavity 1218, a back wall 1214, and a peripheral front opening wall 1210. The composite striking insert 1216 includes a first thickness 1222, a second thickness 1220, and a third thickness 1224. The third thickness 1224 corresponds to a thickened end portion 1212 of the striking insert 1216.
  • The back wall 1214 includes a front engaging surface 1214 a which provides support for the composite insert 1216 to be adhesively attached. The front engaging surface 1214 a and the peripheral front opening wall 1210 create the front opening to receive the composite striking insert 1216. The front engaging surface 1214 a is offset from the front surface 1230 of the club head by an offset distance 1226. The offset distance 1226 can be between about 1 mm and about 5 mm or about 4 mm.
  • The offset distance 1226 is greater than or equal to the third thickness 1224 of the striking insert 1216 to enable the striking insert 1216 to sit within the front opening. The striking insert 1216 is located within the front opening so that the front striking insert 1216 surface is flush with the front portion surface 1230 of the club head body 1200. The interior gap cavity 1218 is located between the striking insert 1216 and the front engaging surface 1214 a of the back wall 1214 and can be about 0.1 cc to about 20 cc. In one embodiment, the interior cavity is less than about 10 cc.
  • The interior cavity is entirely defined and surrounded by the striking insert 1216 and the rear back wall 1214 only. The back wall 1214 is in direct adhesive contact with the striking insert 1216 and supports the striking insert 1216. In other words, the thickened peripheral region 1212 of the striking insert is in direct contact with an interior surface of the back wall 1214.
  • It is critical that the central region of the striking insert 1216 is not capable of making direct contact with the back wall 1214 upon impact with the golf ball to avoid unwanted sound and unwanted performance effects. Therefore, a critical distance 1228 of about 1 mm or more is maintained between the front engaging surface 1214 a and a rear surface 1216 a of the striking insert 1216 at a maximum second thickness 1220 location.
  • FIG. 13A illustrates another exemplary embodiment according to another alternative embodiment of a golf club head 1300 including a front portion 1302, a back portion 1306, a sole portion 1308, and a top line portion 1304. The golf club head also includes a badge 1330, back wall portion 1332, an interior back wall surface 1328, a protruding portion 1324, an upper edge 1326, a sole thickness 1320, a ledge 1322, a front opening wall 1310, an interior cavity 1334, and a striking insert 1312. The ledge 1322 extends a distance 1316 inwardly and the front opening wall 1310 also extends a distance 1318 as previously described.
  • The striking insert material, of the embodiments described herein, are made of the processes and materials described above but can also be a composite material as described in U.S. patent application Ser. Nos. 10/831,496 (now U.S. Pat. No. 7,140,974), 11/642,310, 11/825,138, 11/998,436, 11/823,638, 12/004,386, 12/004,387, 11/960,609, 11/960,610, and 12/156,947, which are incorporated herein by reference in their entirety. All of the composite inserts described herein can be made according to the processes and composite materials described within the above listed patents and patent applications. For example, in one embodiment, a composite face insert material having a fiber areal weight of less than 200 g/m2 is utilized. In another embodiment, a face insert material has a fiber areal weight less than 100 g/m2. In yet other embodiments, the face insert material has a fiber areal weight less than 150 g/m2.
  • For example, water jet cutting can be utilized to cut the composite face inserts from a sheet of composite material as described in the patents and patent applications incorporated by reference. In addition, the face insert can be formed by CNC cutting
  • Some examples of composites that can be used to form the components include, without limitation, glass fiber reinforced polymers (GFRP), carbon fiber reinforced polymers (CFRP), metal matrix composites (MMC), ceramic matrix composites (CMC), and natural composites (e.g., wood composites). The face insert may also be made of a thermoplastic material, as described herein. In certain embodiments, the composite face inserts described herein are made of a material having a density less than about 1.5 g/cc or less than 2.7 g/cc. By contrast, the golf club head material supporting the face insert can be a titanium material having a density greater than 4 g/cc.
  • FIG. 13A shows a center cross-sectional view of the striking insert 1312 being a constant thickness 1314 (across the face of the striking insert 1312) and the constant thickness 1314 being between about 3.0 mm to about 5.0 mm, or about 3.5 mm to about 4.5 mm.
  • FIG. 13B is a detailed view of a lower portion of the golf club head 1300 shown in FIG. 13A. FIG. 13B shows a non-undercut design. Specifically, a lower leading edge zone 1346 of the club head body is completely filled with material and does not include an undercut or gap within the lower leading edge zone 1346 in a transition region between the striking surface of the club face and the sole portion 1308.
  • FIG. 13B shows a club face plane 1336 which contains the striking surface and is co-planar with the striking surface. Furthermore, the ledge 1322 includes a front engaging surface 1344 that is contained within a ledge plane 1338. The club face plane 1336 and the ledge plane 1338 are substantially parallel with respect to one another. A segment 1342 of the sole portion 1308 is located between the face plane 1336 and the ledge plane 1338.
  • The lower leading edge zone 1346 is defined by the front opening wall 1310, the ledge plane 1338, the club face plane 1336, and the sole portion segment 1342. Within the lower leading edge zone 1346, an undercut or gap is avoided in order to lower the first leading edge groove centerline axis 1348 with respect to the ground 1301. The leading edge groove centerline axis 1348 is defined as the intersection of a bisectional plane 1352 and the club face plane 1336 at the centerline axis 1348 shown in FIG. 13B.
  • A low leading edge groove centerline axis 1348 is beneficial in allowing a golfer to make engaging contact with a ball sooner upon impact. In addition, a lower leading edge groove centerline axis 1348 may have additional benefits when a golfer mis-hits a ball by improving the quality of contact between the ball and the leading groove or lowest groove.
  • A horizontal plane 1350 contains the leading edge groove centerline axis 1348 and is parallel with the ground surface 1301. The height distance, h, between the horizontal plane 1350 of the leading edge groove axis 1348 and the ground surface 1301 is between about 4 mm and about 10 mm. In certain embodiments, the height distance, h, is between about 4 mm and about 8 mm or between about 4 mm and about 6 mm.
  • FIG. 14A illustrates a magnified view 1400 of the junction between a composite face insert 1404 and a ledge 1418, according to one exemplary embodiment. The composite face insert 1404 includes an end wall 1410 and a rear surface wall 1412. The composite face insert 1404 is attached to a front opening wall 1408 and front ledge surface 1406 by an adhesive 1414. The adhesive 1414 is applied over a majority of the interface between the composite face insert 1404 and the front opening wall 1408 and front ledge surface 1406.
  • The front ledge surface 1406 intersects with the front opening wall 1408 at a rounded corner location 1416. The corner 1416 includes a radius of between about 0.1 mm and about 0.5 mm. In certain embodiments, the radius is at least about 0.30 mm or greater. A larger corner 1416 radius will avoid high stress concentrations that may result in material failure of the ledge 1418 after repeated use.
  • The rear bond gap distance, x, is located between the front ledge surface 1406 and the rear surface wall 1412. The rear bond gap distance, x, is measured along an axis that is perpendicular to the face plane toward a rear portion of the club head.
  • The side bond gap distance 1402 between the end wall 1410 and the front opening wall 1408 is between 0.1 mm and 0.5 mm, or about 0.3 mm or less. In one embodiment, the side bond gap distance 1402 and the rear bond gap distance, x, are filled with an adhesive epoxy to attach the composite insert 1404.
  • In certain embodiments, the rear bond gap distance, x, is equal to or greater than the side bond gap distance 1402. In some embodiments, the rear bond gap distance, x, is in accordance with the following inequality:

  • x≧0.2 mm  Eq. 1
  • In the above inequality, the side bond gap distance 1402 is set at a distance of about 0.2 mm. If the rear bond gap distance, x, follows the inequality of Equation 1 described above, the composite face insert 1404 will be securely attached within the front opening. Without maintaining a rear bond gap distance, x, larger than the side bond gap distance 1402, the composite face insert 1404 may become loose after repeated impacts and bending.
  • FIG. 14A also shows a metallic cap 1420 which can be implemented in any of the embodiments described herein. The metallic cap 1420 can be made of a material having a density less than 9 g/cc or less than 5 g/cc such as a titanium alloy, CP titanium, or a nickel based alloy. In addition, the metallic cap 1420 can be a Ni—Cr or Co—Ni alloy with a chrome plated layer formed by electro-plating or electro-forming.
  • FIG. 14B further shows another embodiment similar to FIG. 14A except the metallic cap 1420 is replaced by a polymer or polyurethane front layer 1421 having grooves incorporated thereon. The polymer or polyurethane material can be of the type described in U.S. patent application Ser. No. 11/960,609, already incorporated by reference in its entirety. Both the metallic cap 1420 and polymer or polyurethane layer 1421 cover the entire front surface of the face insert 1404.
  • FIG. 15A illustrates an alternative embodiment 1500 including a composite face insert 1504, a ledge 1518, an end wall 1510, a rear surface wall 1512, a front opening wall 1508, front ledge surface 1506, an adhesive 1514 and a corner 1516, as previously described. The face insert 1504 can include a metallic cap or polyurethane cover as previously described.
  • However, the embodiment shown in FIG. 15A includes an additional step gap 1522 in addition to a side bond gap distance 1502 or bond gap. The side bond gap distance 1502 and the step gap 1522 (measured along an axis parallel to the face plane) create a total engineering gap 1520. The step gap 1522 is created by a step region 1524. The step region 1524 and step gap 1522 are present about the entire circumference of the front opening wall 1508.
  • As shown, the side bond gap 1502 and step gap 1522 are filled with the adhesive 1514. The adhesive 1514 in the front portion parallel with the face plane to avoid unwanted bumps or sharp edges on the striking face.
  • In one embodiment, the total engineering gap 1520 is about 0.5 mm and the side bond gap distance 1502 is about 0.2 mm. As a result, the step gap 1522 is about 0.3 mm. The total engineering gap 1520 can be between about 0.2 mm and about 1 mm or between about 0.2 mm and about 0.8 mm.
  • The engineering gap 1520 enables the composite face insert 1504 to be attached without maintaining a perfect side bond gap distance 1502 about the entire circumference of the face insert 1504. For example, the embodiment of FIGS. 14A and 14B, without a step gap and engineering gap would require the exact placement of the composite face insert centered within the front opening to achieve a consistent side bond gap distance. An inconsistent side bond gap distance, without an engineering gap, would be clearly seen by the user and would have a negative impact on aesthetic appeal and performance parameters. In other words, the composite face insert without an engineering gap may look off-center to the golfer and negatively impact the golfer's performance.
  • FIG. 15B is a front view of a composite face insert with an engineering gap 1520. The side bond gap distance 1502 and step gap 1522 are also shown. Within the face plane, the engineering gap 1520, the side bond gap distance 1502, and the step gap 1522 are measured along an axis that is perpendicular to the end wall 1510 at any given point along the outer peripheral edge of the composite face insert 1504 (within the face plane). The front opening wall 1508 is shown in dashed lines from a front perspective.
  • The above described engineering gap distance, side bond gap distance and step gap distance can be applied to any of the embodiments described herein. It is understood that the gaps shown in FIG. 15B are exaggerated for clarity.
  • FIGS. 16-18 illustrate similar embodiments to FIGS. 11-13B, having similar features except the club heads are filled with a filler material.
  • FIG. 16 illustrates a cross sectional view of an alternative embodiment of a golf club head 1600. The cross section is taken through an ideal striking point in the center of the striking face as previously described.
  • The club head 1600 includes a front portion 1602, back portion 1606, a top line portion 1604, and a sole portion 1608. The club head 1600 further includes an upper back wall 1632, a lower back wall 1628, a badge 1630, a sole thickness 1622, a rear protrusion 1624, and filler material 1614. The badge 1630 is positioned above an upper edge 1626 and covers an aperture 1638 used for introducing the plug 1640 and filler material 1614 into the interior cavity of the club head 1600. The filler material 1614 and plug 1640 can be of the same configuration, material, and keying design as described in U.S. patent application Ser. No. 12/462,198, incorporated by reference herein, in its entirety.
  • FIG. 16 further shows a front opening wall 1636, a ledge distance 1618, a depth distance 1620, a first thickness 1611, a second thickness 1616, a third thickness 1610, a ledge 1634, and a composite face insert 1612, previously described.
  • In one embodiment, the filler material can be an expandable foam such as Expancel® 920 DU 40 which is an acrylic copolymer encapsulating a blowing agent, such as isopentane. A copolymer is greater than about 75 weight percent of the composition and the blowing agent is about 15-20 weight percent. The unexpanded particle size of the filler material can be between about 2 μm and about 90 μm depending on the context.
  • In one embodiment, the density of the filler material is between about 0.16 g/cc and about 0.19 g/cc. In certain embodiments, the density of the filler material is in the range of about 0.03 g/cc to about 0.2 g/cc, or about 0.04-0.10 g/cc. The density of the filler material impacts the COR, durability, strength, and filling capacity. In general, a lower density material will have less of an impact on the COR of a club head. The filler material can have a hardness range of about 15-85 Shore OO hardness or about 80 Shore OO hardness or less.
  • In one embodiment, the filler material is subject to heat for expansion of about 150° C.+/−10° C. for about 30 minutes. In some embodiments, the expansion of the filler material can begin at about 125° C. to about 140° C. A maximum expansion temperature range can be between about 160° C. to about 190° C. The temperature at which the expansion of the filler material begins is critical in preventing unwanted expansion after the club head is assembled. For example, a filler material that begins expanding at about 120° C. will not cause unwanted expansion when the club is placed in the trunk of a car (where temperatures can reach up to about 83° C.). Thus, a filler material that has a beginning expansion temperature of greater than about 80° C. is preferred.
  • Some other examples of materials that can be used as a filler material or plug material include, 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; silicone; and mixtures thereof. The metallized polyesters and acrylics can comprise aluminum as the metal. Commercially available materials include resilient polymeric materials such as Scotchdamp™ from 3M, Sorbothane® from Sorbothane, Inc., DYAD® and GP® from Soundcoat Company Inc., Dynamat® from Dynamat Control of North America, Inc., NoViFlex™ Sylomer® from Pole Star Maritime Group, LLC, Isoplast® from The Dow Chemical Company, and Legetolex™ from Piqua Technologies, Inc. In one embodiment the filler material may have a modulus of elasticity ranging from about 0.001 GPa to about 25 GPa, and a durometer ranging from about 5 to about 95 on a Shore D scale. In other examples, gels or liquids can be used, and softer materials which are better characterized on a Shore A or other scale can be used. The Shore D hardness on a polymer is measured in accordance with the ASTM (American Society for Testing and Materials) test D2240.
  • In certain embodiments, the interior cavity of the club head 1600 can includes the plug 1640 for absorbing vibration. It is understood, that an embodiment without the plug 1640 is within the scope of the present description.
  • After the plug 1640 is frictionally engaged in a position, the filler material 1614 can be inserted into the cavity. In certain embodiments, the plug 1640 is a polymeric material.
  • In one embodiment, the plug 1640 material is a urethane or silicone material having a density of about 0.95 g/cc to about 1.75 g/cc, or about 1 g/cc. The plug 1640 can have a hardness of about 10 to about 70 shore A hardness. In certain embodiments, a shore A hardness of about 40 or less is preferred.
  • The filler material 1614 can be an expanding foam material that is expanded by a certain amount of heat as previously described. The filler material 1614 expands and fills a relatively large volume, greater than the volume occupied by the plug 1640.
  • In some embodiments, the volume of the cavity is between about 1 cc and about 200 cc, or between about 10 cc and about 20 cc. For the purposes of measuring the cavity volume herein, the aperture 1638 is assumed to be removed from the back wall 1632 and an imaginary continuous back wall or substantially planar back wall is utilized to calculate the cavity volume.
  • In some embodiments, the filler material 1614 occupies about 50% to about 99% of the total club head cavity volume while the plug 1640 occupies between about 0% to about 20% of the total cavity volume. In specific embodiments, the plug 1640 occupies between about 0.1 cc and 1 cc with the remainder of the cavity volume being filled by the filler material 1614. It is understood that any of the embodiments described herein can be provided without a plug and filler material.
  • In order to achieve a desirable CG location, the filler material 1614 and plug 1640 must be lightweight. In certain embodiments, the total mass of the filler material 1614 and plug 1640 is less than about 5 g or between about 2 g and about 4 g. In one embodiment, the total weight of the filler material 1614 and the plug 1640 is 10 g or less or about 3 g or less. In certain embodiments, the total weight of the filler material 714 and plug 1640 is less than 2% of the total weight of the club head 1600 (excluding any badges, filler material/plug, and ferrule ring). In other embodiments, the total weight of the filler material 714 and plug 1640 is less than about 10% of the total weight of the club head 1600.
  • In some embodiments, the total weight of the filler material 1614 and plug 1640 is between about 1% and about 5% of the total weight of the club head (excluding the badges, filler material/plug, and ferrule ring). Thus, a desirable CG location is still attainable while improving the sound and feel of the golf club head. In certain embodiments, the plug 1640 can weigh about 0.5 g to about 1 g and the filler material 1614 can weigh about 5 grams or less. In some embodiments, the plug 1640 weighs about 0.7 g or less. In other embodiments, the plug 1640 can be equal to or heavier than the total filler material weight.
  • In yet other embodiments, the filler material 1614 and the plug 1640 have a combined weight of less than 20% of the total club head weight (excluding badges, filler material/plug, and ferrule ring). In one embodiment, the combined weight of the filler material 1614 and plug 1640 is less than 5%.
  • FIG. 17 illustrates an alternative embodiment of a golf club head 1700 including a front portion 1702, a rear portion 1706, a sole portion 1708 and a top line portion 1704. The club head 1700 includes a front opening located in the front portion 1702. The club head 1700 further includes a composite striking insert 1716, filler material 1718, a back wall 1714, and a peripheral front opening wall 1710. It is possible to include a plug, badge, and aperture as described above. The striking insert 1716 includes a first thickness 1722, a second thickness 1720, and a third thickness 1724. A critical distance 1728 having dimensions described above is also present. The peripheral region 1712 is in contact with the front surface of the rear wall 1714. The front surface of the rear wall 1714 is located at an offset distance 1726, previously described.
  • The filler material 1718 can be of the type already described above or can be a thermoplastic elastomer having a density of about 0.9 g/cc to about 1.20 g/cc.
  • FIG. 18 shows a top line portion 1804, back portion 1806, front portion 1802, sole portion 1808, back wall portion 1832, badge 1830, interior back wall surface 1828, upper edge 1826, protruding portion 1824, ledge 1822, sole thickness 1820, offset distance 1818, ledge distance 1816, constant face thickness 1814, front opening wall 1810, and filler material 1834, as previously described.
  • In certain embodiments, the badges and composite face inserts, described herein, can be adhesively attached with epoxy or any known adhesive. For example, an epoxy such as 3M® DP460 can be used. It is possible for the badge 1830 to be mechanically attached to the back portion 1806 of the club head 1800.
  • After the hollow iron 1800 is filled with the filler material 1834, the badge 1830 is adhesively or mechanically attached to the back wall 1832 to cover or occlude the aperture to prevent filler material from leaving the cavity and also to achieve a desired aesthetic and while creating further dampening.
  • In some embodiments, the COR is greater than about 0.790. The COR is at least 0.80 as measured according to the USGA Rules of Golf based on a 160 ft./s ball speed test and the USGA calibration plate. The COR can even be as high as 0.83.
  • In one embodiment, the body portion is made from 17-4 steel. However another material such as carbon steel (e.g., 1020, 1030, 8620, or 1040 carbon steel), chrome-molybdenum steel (e.g., 4140 Cr—Mo steel), Ni—Cr—Mo steel (e.g., 8620 Ni—Cr—Mo steel), or austenitic stainless steel (e.g., 304, N50, or N60 stainless steel, 410 stainless steel) can be used.
  • The components of the described components disclosed in the present specification can be formed from any of various suitable metals or metal alloys.
  • In addition to those noted above, some examples of metals and metal alloys that can be used to form the components of the parts described include, without limitation: titanium alloys (e.g., 3-2.5, 6-4, SP700, 15-3-3-3, 10-2-3, or other alpha/near alpha, alpha-beta, and beta/near beta titanium alloys), aluminum/aluminum alloys (e.g., 3000 series alloys, 5000 series alloys, 6000 series alloys, such as 6061-T6, and 7000 series alloys, such as 7075), magnesium alloys, copper alloys, and nickel alloys.
  • The body portion can include various features such as weighting elements, cartridges, and/or inserts or applied bodies as used for CG placement, vibration control or damping, or acoustic control or damping. For example, U.S. Pat. No. 6,811,496, incorporated herein by reference in its entirety, discloses the attachment of mass altering pins or cartridge weighting elements.
  • FIG. 19 shows a golf club head 1900 having a heel 1902, toe portion 1904, sole portion 1908, top line portion 1906, striking face 1910, scoreline grooves 1912, a center point 1901, a CG x-axis 1905, a CG z-axis 1903, a CG z-up axis, a ground plane 1911 as previously described in FIG. 10A.
  • However, the composite face insert 1916 does not extend across the striking surface to a toe portion 1904 edge 1920 as shown in FIG. 19. The composite face insert 1916 occupies about 50% to about 90% of the front striking surface plane. Subsequently, about 50% to about 10% of the front striking surface plane is comprised of the metallic material similar to the golf club head body.
  • Including a smaller percentage of composite face insert 1916 striking surface area can result in a significant reduction in manufacturing cost and composite material savings.
  • At least one advantage of the present invention is that a lightweight composite face insert will provide an improved CG club head location.
  • In addition, a certain engineering gap can be utilized to reduce the manufacturing time and expense associated with perfectly centering a composite face insert in a front opening of the golf club head.
  • At least another advantage of the embodiments described above, is that a rear back wall and badge can act to create an enclosed cavity behind the composite face so that the ledge and adhesive material used to bond the face insert to the club body is not visible to the user.
  • At least another advantage of the embodiments described is that a lightweight filler material arrangement is created allowing the center of gravity of the hollow iron construction to remain low while improving the sound and feel of the club during use.
  • The embodiments described herein conform with the USGA (United States Golf Association) Rules of Golf and Appendix II, 5c related to the Determination of Groove Conformance (issued in August 2008). For example, clubs having a loft of 25 degrees or higher meets the groove width, groove depth, groove separation, groove consistency, area limitations, and edge radius requirements set forth by the USGA. In the embodiments described herein, less than 50% of measured values of Area/(Width+Separation) are greater than 0.0030 in2/in and no single measured value of Area/(Width+Separation) value for any single groove is greater than 0.0032 in2/in.
  • With respect to a groove edge radius, the groove edges are in the form of a radius having an effective radius not less than 0.010″ as described by the two circles method described in the USGA rules. In addition, the effective radius is not greater than 0.020″. In the embodiments described, less than 50% of the upper groove edges or lower groove edges fails the two circles method subject to a 10 degree angular allowance as described in the USGA rules. No single groove edge protrudes more than 0.0003″ outside the outer circle.
  • In some examples, golf club heads are described with reference to a Coefficient of Restitution (COR) that is based on a ratio of a difference between ball speed and club head speed after impact to club head speed prior to impact. A COR of 1 corresponds to a maximum theoretical ball speed and a COR of 0 corresponds to a ball and club head moving together after impact. A COR of 0.83 or less is a suitable design goal for most club heads to insure compliance with USGA rules. Club heads can also be described with reference to a Characteristic Time (CT) that is associated with a time duration in which an object remains in contact with a club face. A CT of about 257 μs or less is a suitable design goal, corresponding to a current USGA limit of 239 μs plus a USGA tolerance of 18 μs. Thinner club faces tend to be associated with relatively larger COR and CT values.
  • Wood type golf club heads generally have dimensions selected to conform to USGA requirements. A wood type golf club head that conforms to USGA Rules can have dimensions no greater than about 71.1 mm from club sole to club crown, 127 mm from club toe to club heel, and 127 mm from club face to a backmost portion of the club head when held in a standard address position. In addition, total club head volume cannot exceed 470 cm3, including a 10 cm3 tolerance.
  • At club head/golf ball impact, a club striking face is deformed so that vibrational modes of the club head associated with the club crown, sole, or striking face are excited. The geometry of most golf clubs is complex, consisting of surfaces having a variety of curvatures, thicknesses, and materials, and precise calculation of club head modes may be difficult. Club head modes can be calculated using computer-aided simulation tools. For any manufactured club heads, and acoustic signal produced with ball/club impact can be evaluated as described below to select suitable club head characteristics for a desired club sound. Some club heads that are suitable for the following methods are described in U.S. patent application Ser. No. 11/960,609, filed Dec. 19, 2007.
  • Generally, club face acoustic modes at frequencies less than about 3 kHz, 3.5 kHz, or 3.8 kHz are associated with unpleasant sounds when used to strike a golf ball. Acoustic modes at these frequencies in the sole or crown can also cause a club to have an unpleasant sound. Conventional titanium or steel faces tend to exhibit such resonance frequencies due to the combination of material density, striking plate thickness, and elastic constant for the large club faces preferred by many golfers. However, with a composite striking plate, material properties are substantially changed so that face acoustic resonance frequencies can be raised to frequencies of 3.9 kHz, 4.0 kHz, 4.5 kHz, or higher, thereby providing golf clubs that have satisfactory sound characteristics. Because sound quality is particularly significant for driver type clubs, such clubs are discussed herein but other clubs such as fairway woods can be similarly configured, but these clubs have much less tendency to produce unpleasant sounds.
  • Referring to FIG. 20, a method 2000 of evaluating club head sound and modifying a club head based on the evaluation includes making a golf ball and club head impact at 2002 under conditions related to actual play. For example, a golfer can be directed to strike a ball with a club using her normal golf swing, and the sound produced thereby recorded and stored at 2004. Club/ball impact speed can be varied by selecting golfer with differing swing speeds, generally in range of about 50 mph to about 130 mph. Higher swing speeds tend to produce more sound and thus can be more conveniently analyzed. At 2006, a time-varying spectrum is obtained that includes amplitudes (as a function of time) of the various frequency components of the recorded acoustic signal. A complex set of frequency components is generally produced at 2006, and in a step 2008 one or more club head surfaces are selected to determine if one or more frequency components should be associated with particular club head surfaces. For example, at 2008, club head surface displacements for a club head striking surface at one or more selected frequencies (based on the frequency components determined at 2006) are determined by measuring surface vibration or otherwise determined or estimated. At some frequencies, the selected surface (for example, the striking surface) can exhibit little displacement so that this frequency component should be associated with some other club head surface. In some cases, a low or lowest order vibration mode of the striking surface can be observed based on a striking surface displacement pattern. A lowest order mode of a club face is associated with a relatively large displacements at the selected frequency at a striking face center and relatively small (or no) displacements at the striking face perimeter. At 2010, one or more frequencies are associated with a mode of a particular surface. At 2012, a characteristic of the selected surface can be adjusted to increase or decrease a mode frequency, or dampen, or substantially attenuate a selected mode frequency.
  • Although the method 2000 is described with reference to measured values, in some examples, computer simulations using finite element analysis or other modeling methods can be used.
  • Representative data is illustrated in FIGS. 21A-21B. In this example, a driver type test club head (noted as #2 in the following table) with a composite striking plate formed of about 24 layers having an estimated COR of 0.835 and a CT of 269 μs was used to strike a golf ball with a club head speed of about 120 mph. Referring to FIG. 21A, acoustic signal amplitude is displayed as a function of time and frequency. For convenience, signal amplitudes are generally color coded in such plots. In FIG. 21A, selected relatively large amplitudes and relatively small amplitudes are noted. Acoustic signal production in response to impact is particularly apparent at times less than about 10-20 ms, with substantial amplitudes persisting at some frequencies for up to about 80 ms. FIG. 21B illustrates vibrational amplitude of the club head striking face at 2120, a club head crown at 2122, and a club head sole at 2124 at a selected frequency of about 3.84 kHz. Thus, this frequency corresponds primarily to a vibrational mode of the striking face and to a lesser extent, the crown. The frequency response data is obtained by using a laser vibrometer and an impact hammer at various locations on the club.
  • Driver type test club head #2 in Table 1 below includes a significantly large face area of about 6978 mm2, a volume of about 460 cc and a head mass of about 203 g. It should be noted that driver type test club heads #2, #3, #5, and #6 in Table 1 below are exemplary embodiments of the invention and incorporate a composite type face insert illustrated at least in FIG. 1 and described in detail above. However, the face size of club heads #2, #3, #5, and #6 are significantly larger than previously known composite face drivers. Because the face size is significantly larger, the sound of the club heads have achieved unique sound qualities as described herein. Club heads #1 and #4 are titanium face drivers provided for comparison purposes with the exemplary embodiments of the present invention having a composite face insert.
  • The table below lists measured lowest order striking surface (face) mode frequencies for a variety of driver type club heads. The damping constant provided in Table 1 is measured using ME'scope VES™ (Visual Engineering Series) software from Vibrant Technology Inc. version 5.1.2010.0709. The damping constant of club heads #2, #3, #5, #6, and #7 are at least greater than 0.232 due to the composite face providing a damping effect on a fully metallic body, crown, and sole construction. The damping constant for the composite face clubs range from 0.27 to 0.462 within these examples. The damping constant can be between about 0.25 or 0.3 to about 0.5 or 0.6 for a composite face insert club construction with a metallic body, crown, and sole. The damping increase is primarily due to the composite face construction in club heads 2, #3, #5, #6, and #7. In contrast, club head #1 illustrates a titanium face club head of similar face size and volume but having a significantly reduced amount of damping at 0.232 due to the titanium face construction. In addition, club head #4 appears to have an increased damping constant of 0.639 due to the composite crown construction alone. The damping constant of club head #4 is not increased due to a composite face insert. In some cases, the club heads are provided for acoustic testing only, and do not correspond to USGA rules compliant clubs.
  • TABLE 1 Comparison of Composite Face Clubs and Titanium Face Clubs Face CT Freq. Damp. Club No. Club Description COR (μs) (Hz) Const. Comments 1 Ti Striking Plate 0.846 294 3140 0.232 A008 2 Composite 0.835 269 3839 0.405 A013 Striking Plate 3 Composite 0.813 217 3870 0.462 A013/Ti Striking Plate with Ti Cap 4 Production Club 0.817 228 3930 .639 1.84 kHz sole mode Comparison with Ti Striking 2.55 kHz crown mode Club Plate 5 Composite .822 242 4240 .34 A016 Striking Plate 6 Composite .816 233 4610 .27 A018 Striking Plate 7 Composite 0.82 237 4480 .32 A019/Ti Striking Plate with Ti Cap
  • Representative data for club head #1 of the table above is illustrated in FIGS. 22A-22B. In this example, a driver type test club head with a titanium striking plate having an estimated COR of 0.846 and a CT of 294 μs was used to strike a golf ball with a club head speed of about 120 mph. The club head #1 has been manufactured with a face area of 6978 mm2 and a volume of about 460 cc for comparison purposes with club head #2 and #3. As mentioned above, club heads #2 and #3 have a composite face insert while the club head #1 has a titanium face with no composite material in the face area. Because the face area and volume between club head #1, #2, and #3 are similar, the loudness and frequency of the clubs can be compared between composite face clubs and titanium face clubs while controlling for the face area and volume variables.
  • Referring to FIG. 22A, acoustic signal amplitude is displayed as a function of time and frequency. In FIG. 22A, selected relatively large amplitudes and relatively small amplitudes are noted. Acoustic signal production in response to impact is particularly apparent at times less than about 10-20 ms, with substantial amplitudes persisting at some frequencies for up to about 80 ms. FIG. 22B illustrates vibrational amplitude of the club head striking face at 2220, a club head crown at 2222, and a club head sole at 2224 at a selected frequency of about 3.13 kHz. Thus, this frequency corresponds primarily to a vibrational mode of the striking face and to a lesser extent, the Crown.
  • FIG. 22C illustrates relative acoustic amplitude as a function of frequency associated with club #1 for ball strikes by two players (referred to herein for convenience as “Player A” and “Player B”) with different swing speeds. (The “Player A’ driver swing speed is about 110 mph, with the “Player B” swing speed is about 100 mph). FIGS. 22D-22E are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for the two different players. For reference, a sound level of about 140 dB corresponds to the sound of a rifle shot at a distance of 1 m, 130 dB is a level associated with hearing damage, and 120 dB is a pain threshold. The sone is equivalent to 40 phons, which is defined as the loudness level of a 1 kHz tone at 40 dB SPL (sound pressure level).
  • The loudness (sones), sound power (watts) and acoustic amplitude (dB) data described throughout the present application is obtained through a specific test procedure. The loudness and amplitude are measured using a microphone positioned at exactly 64 inches directly above the ball at impact as measured from the outer surface of the ball to the outer surface of the microphone's sound recording portion. The microphone used in the test procedure is a G.R.A.S. Sound and Vibration pre-polarized microphone type 40AE. The microphone was connected to a Brüel & Kjaer Pulse™ noise and vibration analysis system (model 3160-B-140). The furthest distance of any impact location away from the center-face of the club was 11 mm as measured from the center face to the center point of the impact location. Post-processing of the recorded data was done using the Pulse™ Sound Quality software from Brüel & Kjaer.
  • Data for additional club heads are provided in additional figures. FIG. 23A is a plot of acoustic signal amplitude as a function of time and frequency for club head #3 having a composite face with a titanium cap layer as described in U.S. patent application Ser. No. 11/960,609, filed Dec. 19, 2007, which is incorporated herein by reference in its entirety. Club head #3 also has a measured face area of about 6978 mm2, a volume of about 460 cc, and a mass of about 203 g. Club head #3 is virtually identical to club head #2 except for the addition of the titanium cap layer as described above. FIG. 23B illustrates relative acoustic amplitude as a function of frequency associated with club #3 (A013/Ti) for ball strikes by two players with different swing speeds. FIGS. 23C-23D are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for the two different players.
  • FIGS. 24A-24D illustrate acoustic properties of production club head #4 that has a conventional titanium face. Club head #4 is a comparison club that does not have a composite type club face. The volume of club head #4 is about 446 cc and the estimated face area is about 5229 mm2. Club head #4 has a mass of about 207 g. Club head #4 is unique in that it is the only club head provided with a composite crown construction. This composite crown construction may increase the amount of damping upon impact even though the club face is a titanium construction. FIGS. 24B-24D illustrate vibrational amplitudes at frequencies of about 1.84 kHz, 2.59 kHz, and 3.93 kHz, respectively, corresponding to a sole mode, a crown mode, and a striking face mode. FIG. 24E illustrates relative acoustic amplitude as a function of frequency associated with club #4 for ball strikes by two players with different swing speeds. FIGS. 24F-24G are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for the two different players.
  • FIG. 25A illustrates acoustic properties of club head #5 that has a composite striking plate. Club head #5 has an estimated face area of about 5236 mm2 and a volume of about 448 cc. The head mass of club head #5 is about 203 g. A lowest order striking face acoustic mode is at a frequency of about 4.24 kHz. Lower order modes that appear in FIG. 25A correspond to modes associated with other parts of the club head such as the crown or the sole. FIG. 25B illustrates relative acoustic amplitude as a function of frequency associated with club #5 for ball strikes by two players with different swing speeds. FIGS. 25C-25D are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time for the two different players.
  • FIG. 26 illustrates acoustic properties of club head #6 that has a composite striking plate. Club head #6 has a face area of about 5257 mm2, a volume of about 454 cc and a mass of about 203 g. A lowest order striking face acoustic mode is at a frequency of about 4.61 kHz. Lower order modes that appear in FIG. 26 correspond to modes associated with other parts of the club head such as the crown or the sole
  • FIG. 27 illustrates acoustic properties of club head #7 that has a composite striking plate. Club head #7 has a face area of about 5715 mm2, a volume of about 459 cc and a head mass of about 203 g. Club head #7 also includes a titanium cap layer as described in U.S. patent application Ser. No. 11/960,609, filed Dec. 19, 2007, which is incorporated herein by reference in its entirety. A lowest order striking face acoustic mode is at a frequency of about 4.48 kHz. Lower order modes that appear in FIG. 27 correspond to modes associated with other parts of the club head such as the crown or the sole.
  • FIGS. 28A-28B illustrate sound levels in sones and A-weighted sound pressure, respectively, for ball strikes with a plurality of club heads. As shown in FIGS. 28A and 28B, the Club numbers shown in the x-axis correspond to the club numbers shown in Table 1 shown above. In some cases, multiple prototypes with minor variations but similar overall parameters were tested as shown. For example, club head #2 from Table 1 was tested for loudness and sound pressure levels in four distinct exemplary heads, club #2-1, club #2-2, club #2-3, and club #2-4. The “−1 . . . -4” designation indicates for separate test clubs having the same overall construction and composite face type club head with potentially minor modifications to the construction and varying manufacturing tolerances.
  • FIGS. 28A and 28B also show an additional “competitor club” which includes a fully titanium face construction but has a composite crown similar to the construction of comparison club head #4. Club head #4 and the “competitor club” shown in FIGS. 28A and 28B do not have a composite face insert.
  • As shown in FIG. 28A, Ti strike plates produce sound levels greater than 225 sones. FIG. 28A also illustrates the striking difference between loudness levels between a titanium face driver, a composite face driver, an a composite face driver with a thin titanium exterior cap. It should be noted that all the composite face drivers (without a titanium cap) tested fall below the 225 sones loudness level. For example, club heads #2, #5, and #6 all fall below the 225 sones level irrespective of club head speed (the distinction between Player A and Player B). Club head #3, which has a titanium cap, exceeds the sones limit of 225 slightly when struck at a higher swing speed. However, all composite face club heads (irrespective of whether a titanium cap is present) are below 237 sones and below 240 sones. In other words, club head #2, #3, #5, #6, and #7 all fall below 237 sones and below 240 sones regardless of the two player swing speeds provided and regardless of the presence of a titanium cap construction. For comparison, it is noted that all club heads tested having a fully titanium face have a loudness of greater than 240 sones.
  • As shown in FIG. 28B, A-weighted sound pressures for clubs with Ti striking plates exceed 5 Pa. Sound levels and A-weighted sound pressures less than these values tend to produce satisfactory sounds. It should be noted that all the composite face insert club heads fall below the 5 Pa A-weighted sound pressure level except club head #7. However, club head #7 includes a titanium cap layer and this feature may explain why the A-weighted pressure data is slightly higher for this club. All the composite face clubs including club head #2, #3, #5, #6, and #7 all fall below an A-weighted sound pressure level of about 5.6 Pa regardless of the two types of swing speeds and regardless of whether a titanium cap is present. For comparison, it is noted that all club heads tested having a fully titanium face further have an A-weighted sound pressure level that exceeds 5.6 Pa.
  • All the club head samples listed in FIGS. 28A and 28B have been measured and are represented as data points in FIGS. 29-32. FIGS. 29, 31, and 32 provide data points for loudness and non-weighted sound measurements for the club head samples when struck by Player A only (corresponding to a swing speed of about 110 mph), for ease of illustration.
  • FIG. 29 illustrates a plot of loudness (sones) on the y-axis and face size (mm2) on the x-axis. As noted above, the loudness for the titanium face drivers are clearly much louder than the composite face insert drivers. Also, the loudness of the titanium drivers appear to increase as a function of the face size (face size as measured according to the procedure described below). Based on the sample composite face insert drivers tested, there also appears to be a trend of increased loudness as the face size increases. However, the sample club heads with a composite face insert (regardless of the presence of a Ti cap) are about 50 sones less when compared to a titanium face head construction having the same face size. In some embodiments, the composite face insert construction is at least 45 sones, 35 sones, 25 sones, or 15 sones less than a comparable titanium face club.
  • FIG. 29 further illustrates an expression to define a zone of potential composite face insert embodiments. A linear boundary expression described as Equation 1 is shown below:

  • y=0.0267x+81.667  Eq. 2
  • In Equation 2, y is the sones variable and x is the face size variable. Equation 2 defines an upper limit of a primary composite face insert zone. The primary composite face insert zone extends between a face size of 5,000 mm2 to 8000 mm2 on the x-axis and extends between about 175 sones up to the boundary of Equation 2 described above on the y-axis.
  • FIG. 29 also illustrates a secondary composite face insert zone that extends between a face size of 5,000 mm2 to 7,000 mm2 on the x-axis and extends between 175 sones up to the boundary of Equation 2 described above on the y-axis. A narrower composite face insert zone can also be defined such as a zone having a y-axis limit between 175 sones up to the boundary of Equation 2 and a x-axis limit between a face size of 5,000 mm2 to 6,000 mm2, 5,500 mm2 to 7,000 mm2, 6,000 mm2 to 7,000 mm2, or 6,500 mm2 to 7,000 mm2. In Equation 2, it should be noted that the slope value is a positive number providing a positively sloped upper limit.
  • FIG. 30 illustrates a comparison between face frequency and face size. Because the composite face is lighter than an ordinary titanium face, the face frequency is higher for a composite face. FIG. 30 illustrates a linear boundary equation defined by Equation 3 shown below:

  • y=−0.44x+6300  Eq. 3
  • In Equation 3, the y variable is the primary face frequency mode of the face after an impact force and the x variable is the face size (mm2). In Equation 3, the slope value is negative. As the face size of a club is increased, the frequency appears to decrease as well.
  • As previously discussed, the composite face clubs all fall under 237 sones when impacted at center face. In addition to a low loudness characteristic, the composite face clubs generally have a face frequency greater than 3,800 Hz. When compared with titanium face clubs of similar face size that are less than 5,500 mm2 in FIG. 30, the composite face clubs are at least 200 Hz, 100 Hz, or 50 Hz higher. When compared with titanium face clubs of similar face size that are greater than 6,000 mm2, the composite face clubs are at least 600 Hz, 500 Hz, 400 Hz, 300 Hz, or 200 Hz higher. For composite face clubs having a face size less than 5,500 mm2, the face frequency values ranged from about 4200 Hz to about 4625 Hz. For composite face clubs having a face size greater than 6,000 mm2, the face frequency values ranged from about 3,800 Hz to about 4,500 Hz.
  • Equation 3 defines an lower limit of a primary composite face insert zone. The primary composite face insert zone extends between a face size of 5,000 mm2 to 8000 mm2 on the x-axis and extends between about 4,800 Hz down to the boundary of Equation 3 described above on the y-axis.
  • FIG. 30 also illustrates a secondary composite face insert zone that extends between a face size of 5,000 mm2 to 7,000 mm2 on the x-axis and extends between 4,700 Hz down to the boundary of Equation 3 described above on the y-axis. A narrower composite face insert zone can also be defined such as a zone having a y-axis limit between 4,600 Hz down to the boundary of Equation 3 and a x-axis limit between a face size of 5,000 mm2 to 6,000 mm2, 5,500 mm2 to 7,000 mm2, 6,000 mm2 to 7,000 mm2, or 6,500 mm2 to 7,000 mm2.
  • FIG. 31 illustrates a comparison between a sound pressure level peak un-weighted signal (dB) at impact (by player A) with the club head face size. In general, the composite face club heads have a much lower sound pressure level than metallic clubs having a metallic crown. The data point labeled 3100 in FIG. 31 is a titanium face driver having a composite crown associated with club head #4 in Table 1. Because of the dampening effect of the composite crown, the comparison club head appears to have a lower than usual sound pressure level. However, the dampening provided to lower the sound pressure level is not created by the face. The composite face insert club heads that are shown provide a dampening of sound pressure levels primarily created via the composite face while the body material and crown material is a metallic material in such club heads.
  • FIG. 31 illustrates two linear boundary equations defined by Equations 4 and 5 shown below:

  • y=0.0005x+110  Eq. 4

  • y=0.0005x+108.5  Eq. 5
  • The first proposed limit is Equation 4 and the second proposed limit is Equation 5. In Equations 4 and 5, the y variable is the sound pressure level at impact (by Player A) and the x variable is the face size (mm2). In Equations 4 and 5, the slope value is positive. As the face size of a club is increased, the sound pressure level appears to increase as well.
  • The composite face clubs all fall under 113 dB when struck. When compared with titanium face clubs of similar face size that are greater than 6,000 mm2, the composite face clubs are at least 3 dB, 2.5 dB, 2 dB, 1.5 dB, or 1 dB lower. For composite face clubs (without a titanium cap) having a face size less than 5,500 mm2, the sound pressure values ranged from about 109 dB to about 112 dB. For composite face clubs (without a titanium cap) having a face size greater than 6,000 mm2, the sound pressure values ranged from about 109 dB to about 112 dB. An outlier data point 3102 occurring between 112 dB and 113 dB, at a face size between 5,500 mm2 and 6,000 mm2, is associated with a composite face insert having a titanium cap layer which is within the scope of this invention. It should be noted that the club head associated with data point 3102 is slightly higher in sound pressure levels than other composite face drivers without a titanium cap, but would still be well below the sound pressure levels found in ordinary titanium drivers (without a composite crown).
  • Equations 4 and 5 define an upper limit of a number of composite face insert zone. The primary composite face insert zone (including Ti cap embodiments) extends between a face size of 5,000 mm2 to 8000 mm2 on the x-axis and extends between about 109 dB up to the boundary of Equation 4 on the y-axis. An alternative primary composite face insert zone (excluding Ti cap embodiments) extends between a face size of 5,000 mm2 to 8000 mm2 on the x-axis and extends between about 109 dB up to the boundary of Equation 5 on the y-axis.
  • FIG. 31 also illustrates a secondary composite face insert zone (including Ti cap embodiments) that extends between a face size of 5,000 mm2 to 7,000 mm2 on the x-axis and extends between 109 dB up to the boundary of Equation 4 described above on the y-axis. An alternative second composite face insert zone (including Ti cap embodiments) extends between a face size of 5,000 mm2 to 7,000 mm2 on the x-axis and extends between 109 dB up to the boundary of Equation 5.
  • A narrower composite face insert zone can also be defined such as a zone having a y-axis limit between 109 dB up to the boundary of Equation 4 or 5 and a x-axis limit between a face size of 5,000 mm2 to 6,000 mm2, 5,500 mm2 to 7,000 mm2, 6,000 mm2 to 7,000 mm2, or 6,500 mm2 to 7,000 mm2.
  • FIG. 32 illustrates a comparison between a sound pressure level peak un-weighted signal (dB) at impact (by Player A) with the club head face size. In general, the composite face club heads have a much lower sound pressure level than metallic clubs having a metallic crown. Again, club head #4 labeled 3200 in FIG. 32 is a titanium face driver having a composite crown. As mentioned above, because of the dampening effect of the composite crown, the comparison club head appears to have a lower than usual sound pressure level. However, the dampening provided to lower the sound pressure level is not created by the face in the club head associated with this data point 3200.
  • A primary composite face insert zone extends between frequency of 3,800 Hz to 4,800 Hz on the x-axis and extends between about 105 dB up to 114 dB on the y-axis. An alternative primary composite face insert zone (that does not include composite crown clubs) extends between a frequency of 4,000 Hz to 4,800 Hz on the x-axis and extends between about 105 dB up to 114 dB on the y-axis.
  • FIG. 32 also illustrates a secondary composite face insert zone that extends between a frequency of 3,800 Hz to 4,700 Hz on the x-axis and extends between 109 dB up to 112 dB on the y-axis. An alternative second composite face insert zone extends between a frequency of 4,000 Hz to 4,700 Hz on the x-axis and extends between 109 dB up to 112 dB on the y-axis.
  • A narrower composite face insert zone can also be defined such as a zone having a y-axis limit between 109 dB up to 110 dB or 111 dB and a x-axis limit between a frequency of 3,800 Hz to 4,000 Hz, 4,000 Hz to 4,400 Hz, 4,400 Hz to 4,600 Hz, or 4,600 Hz to 4,800 Hz. All the composite face club heads tested in FIG. 32 have face size greater than at least 5,000 mm2.
  • Thus, by varying striking face density, elastic constant, thickness, CT, COR, or other striking face property a suitable club head sound can be achieved. In some examples, club head sound levels in response to ball strikes at club head speeds of between 100-120 mph are less that 5 Pa (A-weighted) or less than 225 sones are suitable. Face resonance frequencies of 3.9 kHz, 4.2 kHz, or 4.4 kHz or greater are associated with suitable “pleasing” shot sounds. In some examples, a face thickness can be varied or a face thickness can be modified by local thinning or thickening at or near acoustic resonance nodes and/or antinodes.
  • While the above discussion is generally directed to improving sound characteristics (i.e., providing more pleasant sounds), in other examples club heads can be configured to produce unpleasant sounds or have other sound characteristics. Sound characteristics can be adjusted to provide a more aggressive or less pleasing sound by, for example, providing face resonances at frequencies less than about 3.5 kHz and/or amplitudes greater than about 225 sones or A-weighted pressures of greater than about 5 Pa. It will be appreciated that the examples disclosed herein are not to be taken as limiting the scope of the disclosure, and I claim all that is encompassed by the appended claims.
  • In certain embodiments, the total mass of the golf club head is between 185 g and 215 g or between 190 g and 210 or between about 194 g and 205 g. In similar embodiments, the volume of the golf club head as measured according to the USGA rules is between 390 cc and about 475 cc, or between about 410 cc and 470 cc, or between about 400 cc to about 475 cc, or greater than 400 cc. In certain embodiments, the coefficient of restitution is greater than 0.80 or 0.81 or between about 0.81 and 0.83 as measured according to the USGA rules of golf. Furthermore, the COR in the club heads of the present invention are between 0.80 and 0.81, or between 0.81 and 0.82, or between 0.82 and 0.83, or between 0.83 and 0.84. In some cases, a COR is achieved between 0.80 and 0.84. In addition, in some embodiments, the characteristic time is greater than 230 μs or 220 μs or between about 230 μs and 257 μs as measured according to the USGA rules.
  • The golf club head has a head origin defined as a position on the face plane at a geometric center of the face. The head origin includes an x-axis tangential to the face and is generally parallel to the ground when the head is in an address position. At the address position, a positive x-axis extends towards the heel portion and a y-axis extends perpendicular to the x-axis and is generally parallel to the ground. A positive y-axis extends from the face and through the rearward portion of the body and a z-axis extends perpendicular to the ground, to the x-axis and to the y-axis when the head is ideally positioned. Furthermore, a positive z-axis extends from the origin and generally upward.
  • In the metal-wood embodiments described herein, the “face size” or “face area” or “striking surface area” of “face size surface area” is defined according to a specific procedure described herein. A front wall extended surface 3306 is first defined which is the external face surface that is extended outward (extrapolated) using the average bulge radius (heel-to-toe) and average roll radius (crown-to-sole). The bulge radius is calculated using five equidistant points of measurement fitted across a 2.5 inch segment along the surface of the face as projected from the x-axis (symmetric about the center point). The roll radius is calculated by three equidistant points fitted across a 1.5 inch segment along the surface of the face as projected from the y-axis (also symmetric about the center point).
  • The front wall extended surface 3306 is then offset by a distance of 0.5 mm towards the center of the head in a direction along an axis that is parallel to the face surface normal vector at the center of the face. The center of the face is defined according to USGA “Procedure for Measuring the Flexibility of a Golf Clubhead”, Revision 2.0, Mar. 25, 2005.
  • FIG. 33A illustrates the front wall extended surface 3306 after it has been offset by the 0.5 mm distance. A face front wall profile shape curve 3308 is defined at the intersection of the external surface of the head 3300 with the offset front wall extended surface 3306. A cylindrical section 3302 is also defined having a 30 mm diameter cylindrical surface that is co-axial with the shaft or hosel axis. The intersection of the face front wall profile shape curve 3308 with the cylindrical section 3302 occurs at a first intersection point 3314. Futthermore, a sectioning line 3304 is drawn from the first intersection point 3314 along the surface of the club in a direction normal to the hosel axis 3318. The section line 3304 then intersects a second intersection point 3320 that represents the intersection of the front wall profile shape curve 3308 with the section line 3304 as it is extended in a direction normal to the hosel axis. A hosel trimmed front wall profile shape curve 3322 is then created as seen in FIG. 33B. The hosel trimmed front wall profile shape curve 3322 is defined by a portion of the front wall profile shape curve 3308 and the section line 3304 as it extends between the first intersection point 3314 and the second intersection point 3320. The hosel trimmed front wall profile shape curve 3322 contains a first area 3310.
  • A front wall plane is then defined as a plane which is tangent to the face surface at the geometric center of the face using the method defined in Section 6.1 of the USGA Procedure for Measuring the Flexibility of a Golf Clubhead (Revision 2.0 Mar. 25, 2005).
  • The hosel trimmed front wall profile shape curve 3322 is then projected onto the front wall plane, which is a two dimensional surface plane. Subsequently, the projection of the hosel trimmed front wall profile shape curve 3322 on the front wall plane is modified to find the final face area as defined herein. Specifically, in the projection plane at the first intersection point 3314 and the second intersection point 3320, a tangent line 3330,3324 is drawing tangent to the hosel trimmed front wall profile shape curve 3322 (as projected on the front plane) at the intersection points 3314,3320 until the tangent lines 3330,3324 intersect each other at a vertex 3326, as seen in FIG. 33C. These two tangent lines 3330,3324 and the remaining hosel trimmed front wall profile shape curve 3322 together define the “face size” or “face size surface area” as discussed above. In other words, the two tangent lines 3330,3324 create a second area 3328 which is added to the first area 3310 (as projected on a plane) to create the final face size or face size surface area, as seen in FIG. 33C.
  • In certain embodiments, the striking surface has a surface area between about 4,500 mm2 and 6,200 mm2 and, in certain preferred embodiments, the striking surface is at least about 5,000 mm2 or between about 5,300 mm2 and 6,900 mm2 or between about 5,000 mm2 and 7,000 mm2. In some embodiments, the face size surface area includes a metallic material and a composite material which are both located on the front portion of the club head and are within a face size surface area region.
  • In order to achieve the desired face size, mass is removed from the crown material so that the crown material is between about 0.4 mm and 0.8 mm or less than 0.7 mm over at least 50% of the crown surface area.
  • FIG. 34A illustrates a wood-type (e.g., driver or fairway wood) golf club head from a top view of the club head 3400 with a face insert, according to another embodiment. The club head 3400 includes a front portion 3402, a back portion 3404, a heel portion 3418, a toe portion 3410, a striking surface 3416, a hosel 3412, and a crown portion 3406. The club head 3400 also includes a face angle 3401 when at an address position. A hosel plane 3403 is shown which contains a hosel axis 3405. For ease of illustration, striking face score lines are excluded from this view.
  • FIG. 34B shows the club head 3400 from a front view at an address position including a hollow body having a crown portion 3406, a sole portion 3408, and a front portion 3402. The club head 3400 also includes a hosel 3412 which defines a hosel bore defining a hosel axis 3405 and is connected with the hollow body. The hollow body further includes a heel portion 3418 and a toe portion 3410. A striking surface 3416 is located on the front portion 3402 of the golf club head 3400 having score lines or markings 3420. In some embodiments, the striking surface 3416 can include a bulge and roll curvature or a face insert. In the embodiments of the present invention, the striking surface 3416 is at least partially made of a composite material as described in U.S. patent application Ser. Nos. 10/442,348 (now U.S. Pat. No. 7,267,620), 10/831,496 (now U.S. Pat. No. 7,140,974), 11/642,310, 11/825,138, 11/998,436, 11/895,195, 11/823,638, 12/004,386, 12/004,387, 11/960,609, 11/960,610, and 12/156,947, which are incorporated herein by reference in their entirety. The composite material can be manufactured according to the methods described at least in U.S. patent application Ser. No. 11/825,138. A polymer coating is be applied to the composite material as shown in FIGS. 34A-E.
  • In other embodiments, the striking surface 3416 is at least partially made from a metal alloy (e.g., titanium, steel, aluminum, and/or magnesium), ceramic material, or a combination of composite, polymer, metal alloy, and/or ceramic materials. Moreover, the striking face 3416 can be a striking plate having a variable thickness as described in U.S. Pat. Nos. 6,997,820, 6,800,038, 6,824,475, and 7,066,832 which are incorporated herein by reference in their entirety. For example, the face insert can have a total thickness that is within a range of about 1 mm to about 8 mm. The face insert can be made of prepreg plies having a fiber areal weight of less than 100 g/m2.
  • FIG. 34B also shows an inset distance 3442 that defines a distance between the perimeter of the face insert and the perimeter of the striking surface 3416. The inset distance 3442 may be less than about 13 mm and greater than 1 mm, less than about 8 mm and greater than 6 mm.
  • FIGS. 34B and 34C generally show a club head origin coordinate system being provided such that the location of various features of the club head (including, e.g., a club head CG) can be determined. In FIGS. 34B and 34C, a club head origin point 3422 is represented on the club head 3400. The club head origin point 3422 is positioned at the ideal impact location which can be a geometric center of the striking surface 3416.
  • The head origin coordinate system is defined with respect to the head origin point 3422 and includes a Z-axis 3424, an X-axis 3426, and a Y-axis 3428. The Z-axis 3424 extends through the head origin point 3422 in a generally vertical direction relative the ground 3401 when the club head 3400 is at an address position (although the Z-axis 3424, X-axis 3426, and Y-axis 3428 are independent of club head 3400 orientation). Furthermore, the Z-axis 3424 extends in a positive direction from the origin point 3422 in an upward direction.
  • The X-axis 3426 extends through the head origin point 3422 in a toe-to-heel direction substantially parallel or tangential to the striking surface 116 at the origin point 3422. The X-axis 3426 extends in a positive direction from the origin point 3422 to the heel 3418 of the club head 3400 and is perpendicular to the Z-axis 3424 and Y-axis 3428.
  • The Y-axis 3428 extends through the head origin point 3422 in a front-to-back direction and is generally perpendicular to the X-axis 3426 and Z-axis 3424. The Y-axis 3428 extends in a positive direction from the origin point 3422 towards the rear portion or back portion 3404 of the club head 3400.
  • Referring to FIGS. 34B and 34C, the golf club heads described herein each have a maximum club head height (H, top-bottom), width (W, heel-toe) and depth (D, front-back). The maximum height, H, is defined as the distance between the lowest and highest points on the outer surface of the golf club head body measured along an axis parallel to the origin Z-axis 3424 when the club head is at a proper address position. The maximum depth, D, is defined as the distance between the forward-most and rearward-most points on the surface of the body measured along an axis parallel to the origin Y-axis 3428 when the head is at a proper address position. The maximum width, W, is defined as the distance between the farthest distal toe point and closest proximal heel point on the surface of the body measured along an axis parallel to the origin X-axis 3426 when the head is at a proper address position. FIG. 34B further shows a lie angle 3434 between a hosel axis 3424 and a level ground surface 3401 when the head 3400 is at a proper address position. FIG. 34C shows the striking surface 3416 having a face normal vector 3430 that forms a face loft angle 3414. The face normal vector 3430 intersects the origin point 3422 and extends in a positive direction away from the club head body. The face normal vector 3430 is perpendicular to a plane that is tangent to the origin point 3422.
  • The height, H, width, W, and depth D of the club head in the embodiments herein are measured according to the United States Golf Association “Procedure for Measuring the Club Head Size of Wood Clubs” revision 1.0 and Rules of Golf, Appendix II(4)(b)(i).
  • Golf club head moments of inertia are defined about three axes extending through the golf club head CG 3432 including: a CG z-axis extending through the CG 3432 in a generally vertical direction relative to the ground 3401 when the club head 3400 is at address position, a CG x-axis extending through the CG 132 in a heel-to-toe direction generally parallel to the origin X-axis 3426 and generally perpendicular to the CG z-axis, and a CG y-axis extending through the CG 3432 in a front-to-back direction and generally perpendicular to the CG x-axis and the CG z-axis. The CG x-axis and the CG y-axis both extend in a generally horizontal direction relative to the ground 3401 when the club head 3400 is at the address position. In other words, the CG x-axis and CG y-axis lie in a plane parallel to the ground 3401. Specific CG location values are discussed in further detail below with respect to certain exemplary embodiments.
  • The moment of inertia about the golf club head CG x-axis is calculated by the following equation:

  • I CG=∫(y 2 +z 2)dm  Eq. 6
  • In the above equation, y is the distance from a golf club head CG xz-plane to an infinitesimal mass, dm, and z is the distance from a golf club head CG xy-plane to the infinitesimal mass, dm. The golf club head CG xz-plane is a plane defined by the CG x-axis and the CG z-axis. The CG xy-plane is a plane defined by the CG x-axis and the CG y-axis.
  • Moreover, a moment of inertia about the golf club head CG z-axis is calculated by the following equation:

  • I CG=∫(x 2 +y 2)dm  Eq. 7
  • In the equation above, x is the distance from a golf club head CG yz-plane to an infinitesimal mass dm and y is the distance from the golf club head CG xz-plane to the infinitesimal mass dm. The golf club head CG yz-plane is a plane defined by the CG y-axis and the CG z-axis. Specific moment of inertia values for certain exemplary embodiments are discussed further below.
  • FIG. 34D shows a sole view of an exemplary embodiment club head 3400 including a front portion 3402, a rear portion 3404, a heel portion 3418, a toe portion 3410, a crown portion 3406, and a sole portion 3408. A movable weight 3436 is located within a weight port 3438 in the heel portion 3418 of the sole 3408. The movable weight 3436 increases the MOI of the club head while lowering the CG location. In addition a badge 3440 is located on the sole portion 3408 of the club head near the rear portion 3404 of the club head. The badge 3440 contains identifying indicia such as the club head name, for example.
  • FIG. 34E illustrates a cross-sectional profile view 3444 of the golf club head taken along horizontal sectional lines 34E-34E in FIG. 34B. The heel-side support structure 3448 includes a non-undercut region 3456 within the heel-side region of the club head. The heel-side rear support member 3452 is integral with the internal hosel tube structure 3454. The outer surface of the internal hosel tube structure 3454 directly connects to the non-undercut region 3456. The non-undercut region 3456 extends toward the face away from the outer surface of the internal hosel tube structure 3454 to form the heel-side rear support member 3452. In contrast, the toe-side support structure 3446 includes an undercut region 3450 within the toe-side region of the club head. As seen in FIG. 34E, the most aggressive undercut structure occurs on the toe-side of the club head due to the fact that structural failure is less likely to occur when a mishit occurs on the toe-side of the club head.
  • FIG. 35 illustrates a golf club head 3500 sectional view when taken along section lines 35-35 in FIG. 34A showing a rear portion of the striking face and insert 3518, a toe portion 3534, a heel portion 3536, a crown portion 3538, and a sole portion 3540. The striking face includes a front opening 3530 having a face insert support structure 3516 that includes a rear support member 3532. The face insert 3518 is attached at the front opening 3530 and thereby closes the front opening of the body when the club head is fully assembled. The face insert 3518 has a face insert area which is defined as the frontal surface area of the face insert 3518 when viewed from the front of the club head. In one embodiment, the face insert 3518 has a variable thickness with a thickest portion 3520 located near the geometric center of the face insert 3518 and thinner face insert 3518 portions located near the peripheral edges of the face insert 3518. The rear support member 3532 provides a ledge for which the face insert 3518 is supported.
  • A toe undercut portion 3526,3524 is located toward the toe portion 3534 of the golf club head 3500. A heel undercut portion 3514 is located toward the heel portion 3536. A crown non-undercut portion 3522 is located toward a crown portion 3538 and a sole non-undercut portion 3528 is located toward a sole portion 3540.
  • The toe undercut portion 3526,3524 extends from a crown-side toe undercut portion 3524 to a sole-side toe undercut portion 3526. In one embodiment, the heel undercut portion 3514 is located primarily near the crown portion 3538 only as shown in FIG. 35. However, in another embodiment, the heel undercut portion 3514 is located near the crown portion 3538 and the sole portion 3540, similar to the toe undercut portion 3526,3524.
  • FIG. 35 further illustrates a removable shaft system having a ferrule 3502, a sleeve bore 3542 within a sleeve 3504. A shaft is inserted into the sleeve bore 3542 and is mechanically secured (includes adhesive bonding, threaded attachments, pin attachments or other known mechanical connections) to the sleeve 3504. The sleeve 3504 further includes an anti-rotation portion 3544 at a distal tip of the sleeve 3504 and a threaded bore 3506 for engagement with a screw 3510 or mechanical fastener that is inserted into the sole opening 3512 of the club head 3500. In one embodiment, the sole opening 3512 is directly adjacent to a non-undercut portion 3528. The anti-rotation portion 3544 of the sleeve 3504 engages with an anti-rotation collar 3508 which is bonded or welded within the hosel bore or opening of the golf club head 3500. The adjustable loft, lie, and face angle system is described in U.S. patent application Ser. No. 12/687,003 (now U.S. Pat. No. 8,303,431), which is incorporated by reference in its entirety.
  • The embodiment shown in FIG. 35 includes an adjustable loft, lie, or face angle system that is capable of adjusting the loft, lie, or face angle either in combination with one another or independently from one another. For example, a portion of the sleeve 3504, the sleeve bore 3542, and the shaft collectively define a longitudinal axis 3546 of the assembly. The hosel sleeve is effective to support the shaft along the longitudinal axis 3546, which is offset from a longitudinal axis 3548 of the interior hosel tube bore by offset angle 3550. The sleeve can provide a single offset angle that can be between 0 degrees and 4 degrees, in 0.25 degree increments. For example, the offset angle can be 1.0 degree, 1.25 degrees, 1.5 degrees, 1.75 degrees, 2.0 degrees, 2.25 degrees, 2.5 degrees, 2.75 degrees, or 3.0 degrees. The offset angle of the embodiment shown in FIG. 35 is 1.5 degrees. The amount of offset angle can have an impact on the face angle and loft of the golf club head at impact and thus may impact sound. Thus, the club head of FIG. 35 achieves desirably sound properties despite the offset angle.
  • In certain embodiments, the face insert 3518 is adhesively or mechanically attached to the face insert support structure 3516. In one embodiment, an epoxy adhesive such as 3M™ Scotch-Weld™ Epoxy Adhesive DP460 is utilized having a shore D hardness of about 75 to 84. In other embodiments, an epoxy adhesive such as 3M™ Scotch-Weld™ Epoxy Adhesive DP420 is utilized to attach the face insert 3518 to the support structure 3516. It is understood that numerous equivalent adhesives can be used to attach the face insert 3518 to the support structure 3516.
  • With respect to the embodiment of FIGS. 34A-E and FIG. 35, the overall club head weight is about 190 g to about 210 g or between 180 g and 250 g. The club head of the embodiments described herein can have a mass of about 200 g to about 210 g or about 190 g to about 200 g. In certain embodiments, the total mass of the golf club head is between 185 g and 215 g or between about 194 g and 205 g. Additional mass added by the undercut fill material, such as titanium, will have an effect on moment of inertia and center of gravity values as shown in Tables 2 and 3. Table 2 illustrates exemplary MOI that can be achieved by the embodiments described herein.
  • TABLE 2 ICGx ICGy ICGz (kg · mm2) (kg · mm2) (kg · mm2) 180 to 300 290 to 330 390 to 410 170 to 310 280 to 340 380 to 420 160 to 320 270 to 350 370 to 430
  • The embodiments described conform with the U.S.G.A. Rules of Golf and in some examples the ICGz is less than 590 kg·mm2 plus a test tolerance of 10 kg·mm2. In similar embodiments, the moment of inertia about the CG x-axis (toe to heel), the CG y-axis (back to front), and CG z-axis (sole to crown) is defined. In certain implementations, the club head can have a moment of inertia about the CG z-axis, between about 450 kg·mm2 and about 650 kg·mm2, and a moment of inertia about the CG x-axis between about 300 kg·mm2 and about 500 kg·mm2, and a moment of inertia about the CG y-axis between about 300 kg·mm2 and about 500 kg·mm2.
  • Table 3 illustrates exemplary CG location coordinates with respect to the origin point axes.
  • TABLE 3 CGX origin x-axis CGY origin y-axis CGZ origin z-axis coordinate (mm) coordinate (mm) coordinate (mm) 2.8 to 4.5 27 to 32 −1 to −4 2.5 to 5.0 22 to 37 −0.5 to −5   2 to 6 20 to 40  1 to −8
  • The non-undercut regions of the face support area described herein are a solid single piece casting that may have a negative impact on CG location. However, the negative impact on CG location is far outweighed by the durability benefits and performance benefits, such as sound, achieved by having some regions of the face support structure having an undercut while strategically selecting other regions to be without an undercut (as measured according to the methodology outlined above). In certain embodiments, the CG x-axis coordinate is between approximately −5 mm and approximately 10 mm, a CG y-axis coordinate is between approximately 20 mm and approximately 50 mm, and a CG z-axis coordinate between approximately −10 mm and approximately 5 mm.
  • Furthermore, a significant advantage of the present invention is that an adjustable shaft system that adjusts loft, lie, or face angle is implemented in a single golf club head having strategically placed non-undercut and undercut regions to ensure durability while maintaining sound performance characteristics.
  • In similar embodiments, the volume of the golf club head as measured according to the USGA rules is between 390 cc and about 475 cc, or between about 410 cc and 470 cc, or between about 400 cc to about 475 cc, or greater than 400 cc. In certain embodiments, the coefficient of restitution is greater than 0.80 or 0.81 or between about 0.81 and 0.83 as measured according to the USGA rules of golf. Furthermore, the COR in the club heads of the present invention are between 0.80 and 0.81, or between 0.81 and 0.82, or between 0.82 and 0.83, or between 0.83 and 0.85. In some cases, a COR is achieved between 0.80 and 0.85. In addition, in some embodiments, the characteristic time is greater than 230 μs or 220 μs or between about 230 μs and 257 μs as measured according to the USGA rules. In one example of the golf club head shown in FIGS. 34A-E and FIG. 35, a single tested club head had a COR of 0.825 and a characteristic time of 233 μs.
  • The face insert 3518 area and face size, as defined in the above methodology, can be described in a face insert area to face size ratio, as shown below in Equation 8:
  • Face Insert Area - to - Face Size Ratio = Face Insert Area Face Size Ratio Eq . 8
  • The face insert area to face size ratio needs to be greater than about 0.65 and less than 1, greater than about 0.70 and less than 1, or greater than about 0.75 and less than 1. The face insert area to face size ratio is defined as the face insert area divided by the face size according to the offset plane method described above. In the embodiment shown in FIGS. 34A-E and FIG. 35, the face insert is 4,654 mm2 and the face area is 5,678 mm2 thereby providing an exemplary ratio of 0.82.
  • FIGS. 36A-C relate to acoustic properties of the club head construction shown in FIGS. 34A-E and FIG. 35. FIG. 36A is a plot of acoustic signal amplitude (dB) as a function of frequency. In this exemplary embodiment, the club head also has a measured face area or face size of about 5678 mm2, a volume of about 448 cc, and a mass of about 192 g. FIG. 36A illustrates relative acoustic amplitude as a function of frequency for ball strikes by two players with different swing speeds, as described above. FIGS. 36B-36C are graphs illustrating loudness (sones) and acoustic amplitude (dB) as a function of time, respectively for the two different players. In FIG. 36B, a peak loudness value of 219.99 sones is achieved by a player with a higher swing speed, as defined above. A slower swing speed player achieves a peak loudness value of 213.4 sones. In FIG. 36C, a peak amplitude of 111.81 dB is achieved by a higher swing speed player compared to an amplitude of 110.22 dB for a slower swing speed player. The values achieved by the embodiments of FIGS. 34A-E and FIG. 35 are consistent with the results for amplitude and loudness of the previous embodiments described above. However, the embodiment of FIGS. 34A-E and FIG. 35 implements an adjustable loft, lie, and face angle system and a performance enhancing support member having undercut and non-undercut regions while maintaining improved sound characteristics.
  • FIG. 37 illustrates a golf club head cross-sectional view 3700 having a face insert 3734 that includes a composite layer 3706 having a side wall 3736 portion. A cover layer 3704 that is attached to the composite layer 3706 and can include score lines 3738. In one embodiment, the cover layer 3704 can be a polymer cover layer that attaches to the front surface of the composite layer 3706. In another embodiment, the cover layer 3704 can be a metallic titanium such as 6-4 titanium, 10-2-3 titanium, 15-3-3-3 titanium, 7-2 titanium, or commercially pure titanium. In certain embodiments, the cover layer 3704 does not overlap with the side wall 3736 of the composite layer 3706. The side wall 3736 engages either directly or indirectly with a peripheral wall of the support structure that receives the face insert 3734. In other embodiments, the cover layer 3704 acts as a cap where a wrap-around portion of the cover layer 3704 does overlap with the side wall 3736 of the composite layer 3706.
  • FIG. 37 further shows a rear support member 3710, an apex point 3714 on the interior surface contour 3712, an undercut nadir 3720, an interior body surface 3718, an interior surface contour end point 3708, an outer body surface 3702, and a face curvature 3728 that matches the curvature of the golf club head striking face at a given cross-section through the center of the face. For example, if the cross-sectional view is taken through a vertical plane containing the center of the face, the Z-axis origin, and Y-axis origin, the face curvature 3728 would be the roll curvature of the club head as measured according to the method outlined below. Similarly, if the cross-sectional view is taken through a horizontal plane containing the center of the face, the X-axis origin, and Y-axis origin, the face curvature 3728 would be the bulge curvature of the club head as measured according to the method outlined below.
  • The method for determining the face curvature 3728 within any cross-sectional plane through the face center consists of calculating three equidistant points fitted across a 1.5 inch curved segment along the surface of the face. The middle equidistant point is located in the middle of the 1.5 inch segment. The middle equidistant point is located at the face center location and a face curvature line is fitted through the three equidistant points. The face curvature described is a constant radius curvature between the three equidistant points and cannot be an arbitrary complex spline curvature.
  • FIG. 37 further shows an apex offset curvature 3724 that is identical in orientation and curvature to the face curvature 3728. However, the location of the apex offset curvature 3724 is offset or spaced away from the face curvature 3728 along a face normal vector 3730. The apex offset curvature 3724 is offset along the face normal vector 3430 until the apex offset curvature 3724 becomes tangent to an apex point 3714 located on the interior surface contour 3712. Similarly, a nadir offset curvature 3726 is offset along the face normal vector 3430 by an offset distance. The nadir offset curvature 3726 is tangent to the undercut nadir point 3720 as measured along the face normal vector 3430 axis. An undercut distance 3722 is defined between the nadir offset curvature 3726 and the apex offset curvature 3724 as defined along the face normal vector axis 3430. If the undercut distance 3722 is greater than zero (assuming a positive direction is along the face normal vector pointing away from the club head as shown in FIG. 34C), then an undercut is deemed to exist within the cross-sectional plane in question. In some embodiments, the undercut distance 622 is between 0-1 mm, 1-2 mm, 2-3 mm, 4-5 mm, 0-15 mm, 0-10 mm, or between 0-20 mm. In contrast, if the undercut distance 622 is non-existent, zero, or less (assuming a negative direction is along the face normal vector pointing toward the interior of the club head), then an undercut is deemed not to exist within the cross-sectional plane in question. In some instances, an undercut cannot be measured because no nadir point can be identified and therefore the undercut distance is deemed to be non-existent.
  • FIG. 37 further shows a nadir face normal axis 3730 that passes through the nadir point 3720. The nadir face normal axis 3730 is parallel to the face normal vector 3430 but passes through the nadir point 3720 of the undercut instead of the face center. Likewise, an apex face normal axis 3732 passes through the apex point 3714 and is parallel to both the face normal vector 3430 and the nadir face normal axis 3730. An apex thickness 3716 is measured along the apex face normal axis 3732. In one example, the apex thickness is about 5.8 mm. In some embodiments, the apex thickness is between 5 mm and 6 mm, between 4 mm and 7 mm, or between 3 mm and 8 mm.
  • An undercut height 3744 is defined as the distance between the apex face normal axis 3732 and the nadir face normal axis 3730 as measured along a direction perpendicular to both axis 3730,3732. In some embodiments, the undercut height 3744 is between 0-1 mm, 1-2 mm, 2-3 mm, 4-5 mm, 1-15 mm, 1-10 mm, or between 0-20 mm.
  • FIG. 37 also shows an end point face normal axis 3740 that passes through the interior surface contour end point 3708 and is also parallel to the face normal vector 3430. The thickness of the rear support member 3742 at the end point 3708 (i.e. end point thickness) is measured along the end point face normal axis 3740. In the embodiment shown, the end point thickness 3742 is less than the apex thickness 3716. In one example, the end point thickness 3742 is about 1 mm. In some embodiments, the end point thickness 3742 is between 0.2 mm and 2 mm, or between 0.5 mm and 1.5 mm. FIG. 37 also shows a face insert depth 3746 which defines the recess that receives the face insert 3734. The face insert depth 3746 and the end point thickness 3742 define a face insert ratio shown below in Equation 9 below:
  • Face Insert Ratio = Face Insert Depth End Point Thickness Eq . 9
  • In one embodiment, the face insert depth is about 4.5 mm and the end point thickness is about 1 mm thereby creating a ratio of about 4.5. The face insert ratio may generally be between 0.5 and 10. However, in some embodiments, the face insert ratio may be less than 1.0, less than 0.8, or less than 0.7. In other embodiments, the face insert depth 3746 is greater than 0.2 mm and less than 10 mm or greater than 0.5 mm and less than 2.0 mm.
  • An adhesive is disposed between the face insert 3734 and the face insert rear support member 3710. A bond gap is provided between the rear support member 3710 and a rear surface of the composite face 3706 where the adhesive material fills the bond gap. In certain embodiments, the bond gap is less than about 0.8 mm or less than about 0.2 mm. In a preferred embodiment, the bond gap is about 0.15 mm or less. In the exemplary embodiment of FIG. 37, the cover layer 3704 includes an outer edge that is generally coplanar with the edge of the composite face 3706. In other words, the cover layer 3704 does not include a return side wall portion.
  • FIG. 38 illustrates a sound power estimate diagram in accordance with the golf club head shown in FIGS. 34A-E and FIG. 35 as measured using the equipment and methodology disclosed above where the microphone is place 64 inches above the ball impact with player A (i.e. 110 mph swing speed). The sound power estimate diagram shows a maximum peak 3800 in sound power occurs at greater than 3,500 Hz and less than 7,000 Hz. In one embodiment, the maximum peak 3800 sound power is occurring at greater than 3,750 Hz and less than 6,500 Hz. The exemplary golf club head of FIGS. 34A-E and FIG. 35 has a maximum peak 3800 in sound power at 6,003 Hz while producing a sound power greater than about 0.06 watts but less than 0.07 watts, at 0.064 watts. The frequency at maximum sound power can be divided by the offset angle, discussed above, to create a frequency-to-offset angle ratio (frequency divided by offset angle) of between 2,333 Hz/degree to 4,666 Hz/degree for a 1.5 degree offset angle. For a sleeve of about 2 degrees, the frequency-to-offset angle ratio is between 1,750 Hz/degree and 3,500 Hz/degree. The frequency-to-offset angle ratio can range from 1,000 Hz/degree to 7,000 Hz/degree. FIG. 39 illustrates a sound power estimate diagram of a club head similar to that shown in FIGS. 34A-E and FIG. 35. However, the club head tested in FIG. 39 includes a titanium cover layer that is adhesively attached to the composite face insert. The sound power estimate diagram shows a maximum peak 3900 in sound power is occurs at greater than 3,000 Hz and less than 6,000 Hz. In the embodiment shown in FIG. 39, the maximum peak 3900 sound power is occurs at 5,659 Hz while producing a sound power greater than about 0.1 watts but less than 0.2 watts, and greater than 0.125 watts but less than 0.19 watts. The exact sound power generated by the embodiment of FIG. 39 is 0.188 watts.
  • Equation 10 creates a maximum power to frequency ratio defined below:
  • Max . Sound Power - to - Freq . Ratio = Maximum Sound Power Freq . of the Max . Sound Power Eq . 10
  • The maximum sound power-to-frequency ratio is greater than about 2.5*10−5 watts/hertz and less than about 5*10−5 watts/hertz, or greater than 1*10−5 watts/hertz and less than 4.5*10−5 watts/hertz. For example, the embodiment of FIG. 39 has a maximum sound power-to-frequency ratio of about 3.3*10−5 watts/hertz and the embodiment of FIG. 38 has a maximum sound power-to-frequency ratio of about 1.1*10−5 watts/hertz. In some embodiments, the maximum sound power-to-frequency ratio is between 3.0*10−5 watts/hertz and 4.5*10−5 watts/hertz.
  • In addition, a frequency-to-volume ratio at the maximum sound power is defined below in Equation 11:
  • Frequency - to - Volume Ratio = Freq . of Max . Sound Power Volume Eq . 11
  • The frequency-to-volume ratio can be greater than 6.0 hertz/cc and less than about 16 hertz/cc, or greater than 7.0 hertz/cc and less than about 15 hertz/cc, or between 7.0 hertz/cc and 10 hertz/cc. For example, the frequency-to-volume ratio of the exemplary embodiment of FIG. 38 is about 13.4 hertz/cc for a maximum frequency of 6,003 Hz and a volume of 448 cc. In another exemplary embodiment of FIG. 39, the frequency-to-volume ratio is about 13.1 for a maximum frequency of 5,659 Hz and a volume of 430 cc.
  • A characteristic time test was performed on the embodiments of FIGS. 38 and 39, as defined and performed by the USGA in the United States Golf Association Technical Description of the Pendulum Test, Revised Version, Discussion of points raised during Notice & Comment period (November 2003), the disclosure of which is incorporated by reference in its entirety. The procedure of measuring characteristic time and slope is performed according to the R&A Rules Limited and USGA, Procedure for Measuring the Flexibility of a Driving Club, Revision 1.1 (January 2004) publication.
  • The slope formed from the trend-line of the data points used to calculate the characteristic time is defined as the “characteristic time slope”. In the embodiments described, the characteristic slope is greater than 5 and less than 90, or greater than 10 and less than 45, or greater than 10 and less than 50, or greater than 12.5 and less than 30, or greater than 15 and less than 30, or between 15 and 20. In some embodiments, the characteristic slope is between 50 and 60, or between 50 and 90, or between 50 and 80, or between 50 and 150, or between 10 and 150. By way of example, the example club head tested in FIG. 38 has a characteristic time of 231 μs and a characteristic time slope of 62.8. In contrast, the embodiment disclosed in FIG. 39 has a characteristic time of 226 μs and a characteristic time slope of 37.6. FIG. 40 illustrates an example of a characteristic time slope of a club head constructed of the design in FIG. 35 and FIG. 38. In FIG. 40, the characteristic time slope is about 225 μs when corrected according to the USGA rules for a polymer coating described above of about 400 μm. The slope as shown in the equation of FIG. 40 is 65 based on the corrected USGA value. All slopes and CT values discussed herein are the corrected USGA value which accounts for special face coatings such as polymers.
  • The fibers of the composite material are arranged in a quasi-isotropic layup of less than 10 mm thickness, as described above, and can have a layup tensile strength of greater than 100 MPa and less than 9000 MPa, or greater than 200 MPa and less than 1500 MPa, or greater than 300 MPa and less than 1000 MPa. All tests conducted relative to the term “layup”, as used herein, refers to the quasi-isotropic layup after curing when the resin and the panels of carbon fiber have created a uniform face insert body. In one exemplary embodiment shown in FIG. 38, the composite material layup has a tensile strength of about 689 MPa to about 773 MPa with an average of about 737 MPa taken over a plurality of measurements. When examining individual carbon fibers, a high tensile strength composite fiber is contemplated such as composites having a tensile strength of 4.0 GPa and less than 6.0 GPa, or greater than 4.5 GPa and less than about 5.5 GPa. In one exemplary embodiment shown in FIG. 38, the composite fiber has a tensile strength of 4.83 GPa.
  • In addition, the composite material quasi-isotropic layup described above has a tensile modulus of elasticity of greater than 10 GPa and less than 200 GPa, or greater than 20 GPa and less than 150 GPa, or greater than 20 GPa and less than 100 GPa. In one exemplary embodiment shown in FIG. 38, the composite material layup has a tensile modulus of elasticity of about 38 GPa to about 45 GPa, with an average of about 41 GPa taken over a plurality of measurements. When examining individual carbon fibers, a high tensile modulus of elasticity composite fiber is contemplated such as composites having a tensile modulus of elasticity of greater than 200 GPa and less than about 300 GPa, or greater than 225 GPa and less than about 275 GPa. In one embodiment of FIG. 38, the tensile modulus of elasticity of the composite fiber is 234 GPa.
  • A strength-to-modulus layup ratio is defined as the tensile strength of the composite quasi-isotropic layup divided by the tensile modulus of the elasticity of the composite quasi-isotropic layup, as shown in Equation 12:
  • Strength - to - Modulus Layup Ratio = Layup Tensile Strength Layup Tensile Modulus of Elasticity × 100 Eq . 12
  • The strength-to-modulus layup ratio is greater than 0.5 and less than 10.0, or greater than 1.0 and less than 10.0, or greater than 2.0 and less than 8.0, or greater than 1.0 and less than 2.0. In one exemplary embodiment of FIG. 38, the strength-to-modulus layup ratio is about 1.8 (calculated by 737 MPa/41 GPa).
  • Furthermore a strength-to-modulus fiber ratio is defined as the tensile strength of the fiber alone divided by the tensile modulus of the elasticity of the fiber alone, as shown in Equation 13:
  • Strength - to - Modulus Fiber Ratio = Fiber Tensile Strength Fiber Tensile Modulus of Elasticity × 100 Eq . 13
  • The strength-to-modulus fiber ratio is greater than 1.0 and less than 10.0, or greater than 2.0 and less than 8.0, or greater than 2.0 and less than 3.0. In one exemplary embodiment of FIG. 38, the strength-to-modulus fiber ratio is about 2.1 (calculated by 4.83 GPa/234 GPa). When comparing the strength-to-modulus layup ratio and the strength-to-modulus fiber ratio, the embodiment of FIG. 38 shows the strength-to-modulus layup ratio being less than the strength-to-modulus fiber ratio.
  • The exemplary embodiment of FIG. 38 possesses a unique characteristic in that the strength-to-modulus layup ratio of 1.8 is less than the strength-to-modulus fiber ratio of 2.1 satisfying the inequality of Equation 14:
  • 0.5 < strength - to - modulus layup ratio strength - to - modulus fiber ratio < 1 Eq . 14
  • A layup-to-fiber ratio is shown in Equation 14 and is defined as the strength-to-modulus layup ratio divided by the strength-to-modulus fiber ratio. Maintaining a layup-to-fiber ratio within the above described range ensures a durable face insert is produced and can also have a positive impact on the sound characteristics of the overall golf club head. In the exemplary embodiment of FIG. 38, a layup-to-fiber ratio of about 0.86 is produced (calculated by 1.8/2.1). In some embodiments, the layup-to-fiber ratio may be greater than 0.1 and less than 1, or greater than 0.25 and less than 1.
  • In certain embodiments, the club head height is between about 63.5 mm to 71 mm (2.5″ to 2.8″) and the width is between about 116.84 mm to about 127 mm (4.6″ to 5.0″). Furthermore, the depth dimension is between about 111.76 mm to about 127 mm (4.4″ to 5.0″). The club head height, width, and depth are measured according to the USGA rules.
  • In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Claims (20)

We claim:
1. A golf club comprising:
a golf club head with a body having a front portion, a crown portion, a sole portion, and a hosel portion, the body comprised of a first material;
a hosel bore located in the hosel portion;
a sleeve having a sleeve bore, a threaded portion, and an anti-rotation portion, the sleeve being configured to be received in the hosel portion;
a screw configured to engage the threaded portion of the sleeve, the screw also configured to be inserted into a sole opening in the sole portion;
a first longitudinal axis defined by the sleeve bore;
a second longitudinal axis defined by the hosel bore of the hosel portion;
an offset angle located between the first longitudinal axis and second longitudinal axis, the offset angle being between 0 degrees and 4 degrees;
a face portion comprising a second material and being configured to be attached to the front portion of the body, the face portion having a face size surface area being at least at least 4,500 mm2;
a coefficient of restitution greater than 0.79 and a characteristic time greater than 220 μs;
a loudness of the club head is less than 240 sones upon striking a golf ball at about 110 mph, measured by a microphone positioned at 64 inches above the golf ball, wherein the face portion has a characteristic time slope of greater than 10 and less than 150.
2. The golf club of claim 1, wherein the second material is a composite material having a layup-to-fiber ratio of greater than 0.5 but less than 1.
3. The golf club of claim 1, wherein the second material is a composite material having a strength-to-modulus fiber ratio of greater than 1 and less than 10.
4. The golf club of claim 3, wherein the second material includes a strength-to-modulus layup ratio of greater than 0.5 and less than 10.
5. The golf club of claim 1, wherein the face portion further includes a face insert;
a recess that receives the face insert and defines a face insert depth;
a rear support member having an end point thickness; and
a face insert ratio between 0.5 and 10, the face insert ratio being defined as the face insert depth divided by the end point thickness.
6. The golf club of claim 1, wherein a peak un-weighted acoustic amplitude of the club head is less than 114 dB, a peak A-weighted sound pressure level of the club head is less than 5 Pa as measured by the microphone positioned at 64 inches above the golf ball.
7. The golf club of claim 1, wherein the face portion includes a face insert having a face insert area and a face insert area-to-face size ratio of greater than 0.65 and less than 1.
8. The golf club of claim 7, wherein the golf club head further includes a maximum sound power-to-frequency ratio greater than 1*10−5 watts/hertz and less than 4.5*10−5 watts/hertz.
9. The golf club of claim 1, wherein the golf club has a head volume between 400 cc to about 475 cc.
10. The golf club of claim 8, wherein the golf club head has a frequency-to-volume ratio of greater than 6.0 hertz/cc and less than 16 hertz/cc.
11. The golf club of claim 1, wherein the golf club head includes frequency-to-offset angle ratio between 1,000 Hz/degree to 7,000 Hz/degree.
12. The golf club of claim 1, wherein the sole opening is located adjacent to a non-undercut portion.
13. The golf club of claim 12, wherein a heel-side rear support member is integral with an internal hosel tube structure.
14. A golf club comprising:
a golf club head with a body having a front portion, a crown portion, a sole portion, and a hosel portion, the body comprised of a first material;
a face portion comprising a second material and being configured to be attached to the front portion of the body;
a sleeve having a sleeve bore, a threaded portion, and an anti-rotation portion, the sleeve being configured to be received in the hosel portion;
a screw configured to engage the threaded portion of the sleeve, the screw also configured to be inserted into a sole opening in the sole portion;
a first longitudinal axis defined by the sleeve bore;
a second longitudinal axis defined by a hosel bore of the hosel portion;
an offset angle located between the first longitudinal axis and second longitudinal axis, the offset angle being between 0 degrees and 4 degrees;
a peak un-weighted acoustic amplitude of the club head is less than 113 dB upon striking a golf ball at about 110 mph, measured by a microphone positioned at 64 inches above the golf ball, wherein the face portion has a characteristic time slope of greater than 10 and less than 150.
15. The golf club of claim 14, wherein the second material is a composite material having a layup-to-fiber ratio of greater than 0.5 but less than 1.
16. The golf club of claim 14, wherein the second material is a composite material having a strength-to-modulus fiber ratio of greater than 1 and less than 10.
17. The golf club of claim 14, wherein the second material is a composite material having a strength-to-modulus layup ratio of greater than 0.5 and less than 10.
18. A golf club comprising:
a golf club head with a body having a front portion, a crown portion, a sole portion, and a hosel portion, the body comprised of a first material;
a face portion comprising a second material and being configured to be attached to the front portion of the body;
a sleeve having a sleeve bore, a threaded portion, and an anti-rotation portion, the sleeve being configured to be received in the hosel portion;
a screw configured to engage the threaded portion of the sleeve, the screw also configured to be inserted into a sole opening in the sole portion;
a first longitudinal axis defined by the sleeve bore;
a second longitudinal axis defined by a hosel bore of the hosel portion;
an offset angle located between the first longitudinal axis and second longitudinal axis, the offset angle being between 0 degrees and 4 degrees;
a peak A-weighted sound pressure level of the club head is less than 5 Pa upon striking a golf ball at about 110 mph, measured by a microphone positioned at 64 inches above the golf ball, wherein the face portion has a characteristic time slope of greater than 10 and less than 150.
19. The golf club of claim 18, wherein the second material is a composite material having a strength-to-modulus layup ratio of greater than 0.5 and less than 10.
20. The golf club of claim 18, wherein the second material is a composite material having a layup-to-fiber ratio of greater than 0.5 but less than 1.
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