CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. Non-Provisional application Ser. No. 14/624,488, filed on Feb. 17, 2015, which is continuation-in-part of U.S. patent application Ser. No. 14/228,503, filed on Mar. 28, 2014, which claims the benefit of U.S. Provisional Application No. 61/941,117, filed on Feb. 18, 2014, the entire contents of which are fully incorporated herein.

TECHNICAL FIELD

This present disclosure relates generally to sports equipment, and relates more particularly to golf club head assembly.

BACKGROUND

The present invention relates to golf clubs and particularly to a method of forming a golf club head assembly.

Conventional golf club head assemblies include a faceplate welded to a club head. The faceplate has a slightly rounded shape in order to provide a straighter and/or longer flight path for a golf ball, even when the ball is struck off-center with respect to the faceplate. The faceplate has a bulge dimension, or curvature from a toe end to a heel end, and a roll dimension, or curvature from the crown edge to the sole edge.

Aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a club head and a face plate.

FIG. 2 is a perspective view of the club head with the face plate removed.

FIG. 3 is a top view of a club head assembly.

FIG. 4 is a side section view of the club head assembly of FIG. 3 along section 4-4.

FIG. 5 is a side view of the club head assembly of FIG. 3.

FIG. 6 is a schematic view of a process for forming a golf club head assembly.

FIG. 7 is a chart showing experimental bulge and roll measurements for faceplates that are subjected to various heat-treatment processes.

FIG. 8 is a chart showing experimental roll measurements for faceplates having various geometries.

FIG. 9 is a chart showing experimental bulge and roll measurements for faceplates that are subjected to various heat-treatment processes.

FIG. 10. is a chart showing durability measurements for faceplates having various material compositions.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of â€œincluding,â€ â€œcomprising,â€ and â€œhavingâ€ and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. All weight percent (wt %) numbers described below are a total weight percent.

DETAILED DESCRIPTION

FIG. 1-3 shows a golf club head 10 and a faceplate 14. In one embodiment, the golf club head 10 is formed from a cast material and the faceplate 14 is formed from a rolled material. Further, in the illustrated embodiment, the golf club head 10 is for a metal wood driver; in other embodiments, the golf club head 10 is for a fairway wood; in other embodiments, the golf club head 10 is for hybrid clubs; in other embodiments, the golf club head 10 is for an iron club. The club head 10 may also include a hosel and a hosel transition (shown as 18). For example, the hosel may be located at or proximate to the heel end 34. The hosel may extend from the club head 10 via the hosel transition 18. To form a golf club, the hosel may receive a first end of a shaft 20. The shaft 20 may be secured to the golf club head 10 by an adhesive bonding process (e.g., epoxy) and/or other suitable bonding processes (e.g., mechanical bonding, soldering, welding, and/or brazing). Further, a grip (not shown) may be secured to a second end of the shaft 20 to complete the golf club.

As shown in FIG. 2, the club head 10 further includes a recess or opening 22 for receiving the faceplate 14. In the illustrated embodiment, the opening 22 includes a lip 26 extending around the perimeter of the opening 22. The faceplate 14 is aligned with the opening and abuts the lip 26. The faceplate 14 is secured to the club head 10 by welding, forming a club head assembly 30. In one embodiment, the welding is a pulse plasma welding process.

The faceplate 14 includes a heel end 34 and a toe end 38 opposite the heel end 34. The heel end 34 is positioned proximate the hosel portion (hosel and hosel transition 18) where the shaft 20 (FIG. 1) is coupled to the club head assembly 30. The faceplate 14 further includes a crown edge 42 and a sole edge 46 opposite the crown edge 42. The crown edge 42 is positioned adjacent an upper edge of the club head 10, while the sole edge 46 is positioned adjacent the lower edge of the club head 10. As shown in FIG. 3, the faceplate 14 has a bulge curvature in a direction extending between the heel end 34 and the toe end 38. As shown in FIGS. 4 and 5, the faceplate 14 also has a roll curvature in a direction extending between the crown edge 42 and the sole edge 46. In one embodiment, the faceplate may have a minimum wall thickness of 1.5 millimeters, 1.4 millimeters, 1.3 millimeters, 1.2 millimeters, 1.1 millimeters, 1.0 millimeters, 0.9 millimeters, 0.8 millimeters, 0.7 millimeters, 0.6 millimeters, 0.5 millimeters and 0.4 millimeters. In one embodiment, the faceplate may have a minimum wall thickness of 0.7 millimeters.

The faceplate 14 is formed from a titanium alloy. In one embodiment, the faceplate 14 is an Î±-Î² titanium (Î±-Î² Ti) alloy. The Î±-Î² Ti alloy may contain neutral alloying elements such as tin and a stabilizers such as aluminum and oxygen. The Î±-Î² Ti alloy may contain Î²-stabilizers such as molybdenum, silicon and vanadium. All numbers described below regarding weight percent are a total weight percent (wt %). The total weight percent of Î±-stabilizer aluminum in Î±-Î² Ti alloy may be between 2 wt % to 10 wt %, 3 wt % to 9 wt %, 4 wt % to 8 wt %, or 5 wt % to 7 wt %. The total weight percent of Î±-stabilizer oxygen in Î±-Î² Ti alloy may be between 0.05 wt % to 0.35 wt %, or 0.10 wt % to 0.20 wt %. The total weight percent of Î²-stabilizer molybdenum in Î±-62 Ti alloy may be between 0.2 wt % to 1.0 wt %, or 0.6 wt % to 0.8 wt %, or trace amounts. The total weight percent of Î²-stabilizer vanadium in Î±-Î² Ti alloy may be between 1.5 wt % to 7 wt %, or 3.5 wt % to 4.5 wt %. The total weight percent of Î²-stabilizer silicon in Î±-Î² Ti alloy may be between 0.01 to 0.10 wt %, or 0.03 wt % to 0.07 wt %. The Î±-62 Ti alloy may be Ti-6Al-4V (or Ti 6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI 550. The combination of Î±, Î² stabilizers allows the Î±-Î² Ti alloys to be heat treated.

In one embodiment, after welding the faceplate 14 to the club head 10, the club head 10 and faceplate 14 may be heated to a temperature at, just above, or greater than the solvus temperature of the faceplate for a predetermined amount of time. In another embodiment, after welding the faceplate 14 to the club head 10, the club head assembly 30 may be heat treated at a temperature at, just above or greater than the Î±-62 Ti solvus temperature for a predetermined amount of time. In another embodiment, after welding the faceplate 14 to the club head 10, the club head assembly 30 may be heat treated at a temperature at, just above or greater than the Î±-Î² Ti solvus temperature for a predetermined amount of time. Also, during this step, an inert gas may be pumped into the heating chamber housing the club head assembly 30 to remove all oxygen over a predetermined amount of time discussed below. Upon cooling of the club head assembly 30 as discussed below, additional inert gas may be pumped back into the chamber where the club head assembly 30 is allowed to cool to room temperature.

As discussed above, after heating the club head assembly 30 (or the club head 10 and the welded faceplate 14), the club head assembly 30 is allowed to cool to room temperature. In another embodiment, after the heat treatment, the club head assembly 30 may be allowed to air cool to slowly reduce the club head assembly's temperature. The cooling of the club head assembly 30 may be done in an inert gas environment or non-contained environment (open air). In another embodiment, the club head assembly 30 may be allowed to cool in inert gas to slowly reduce the club head assembly's temperature and reduce chance for oxidation. The inert gas may be selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe) or a compound gas thereof. After heating to, just above, or greater than the Î±-Î² Ti solvus temperature, inert gas may be pumped back into a chamber under vacuum housing the club assembly 30, which ensures no oxygen is present to prevent oxidation to the titanium faceplate 14 and club head surfaces 10.

As understood by a person of ordinary skill, the solvus temperature for an alloy is the temperature barrier at which smaller constituent molecules dissolve within the general matrix of the material and become more mobile. The solvus temperatures of most Î±-Î² Ti alloys are verified and readily available in academic literature or information published by material suppliers. If published data is unavailable, the temperature values can be estimated and experimentally confirmed, since it is dependent on the material's chemistry. The solvus temperature for Î±-Î² Ti can be above 400Â° C. and below 600Â° C.

In one embodiment, the Î±-62 Ti may be Ti 6-4 containing 6 wt % aluminum (Al), and 4 wt % vanadium (V), with the remaining alloy composition being titanium and possibly some trace elements. In some embodiments, Ti 6-4 contains between 5.5 wt %-6.75 wt % Al, between 3.5 wt %-4.5 wt % V, a maximum of 0.08 wt % carbon (C), a maximum of 0.03 wt % silicon (Si), a maximum of 0.3 wt % iron (Fe), a maximum of 0.2 wt % oxygen (O), a maximum of 0.015 wt % tin (Sn), and trace amounts of molybedenum (Mo), with the remaining alloy composition being titanium. In some embodiments, Ti 6-4 contains between 5.5 wt %-6.75 wt % Al, between 3.5 wt %-4.5 wt % V, 0.08 wt % or less carbon (C), 0.03 wt % or less silicon (Si), 0.3 wt % or less iron (Fe), 0.2 wt % or less oxygen (O), 0.015 wt % or less tin (Sn), and trace amounts of molybedenum (Mo), with the remaining alloy composition being titanium. Ti 6-4 is a grade 5 titanium. The solvus temperature for Ti 6-4 is between 540Â° C. and 560Â° C. In some embodiments, Ti 6-4 has a density of 0.1597 lb/in³(4.37 g/cc). Ti-6-4 may also be designated as T-65K.

In other embodiments, the faceplate 14 of the golf club head 10 may be another Î±-Î² Ti alloy, such as Ti-9S (or T-9S), which contains 8 wt % Al, 1 wt % V, and 0.2 wt % Si, with the remaining alloy composition being titanium and possibly some trace elements. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt %-8.5 wt % Al, between lwt %-2 wt % V, a maximum of 0.08 wt % C, a maximum of 0.2 wt % Si, a maximum of 0.3 wt % Fe, a maximum of 0.2 wt % O, a maximum of 0.05 wt % N, trace amounts of Mo, and trace amounts of Sn, with the remaining alloy composition being titanium. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt %-8.5 wt % Al, between lwt %-2 wt % V, less than 0.1 wt % C, a maximum of 0.2 wt % Si, a maximum of 0.4 wt % Fe, a maximum of 0.15 wt % O, less than 0.05 wt % N, trace amounts of Mo, and trace amounts of Sn, with the remaining alloy composition being titanium. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt %-8.5 wt % Al, between 1 wt %-2 wt % V, 0.1 wt % or less C, 0.2 wt % or less Si, 0.4 wt % or less Fe, 0.15 wt % or less O, less than 0.05 wt % N, trace amounts of Mo, and trace amounts of Sn, with the remaining alloy composition being titanium. The solvus temperature for Ti-9S (or T-9S) is between 560Â° C. and 590Â° C. In some embodiments, the Ti-9S (or T-9s) will have higher porosity and a lower yield than Ti 8-1-1. Ti-9S (or T-9S) has a density of about 0.156 lb/in³to 0.157 lb/in³(4.32-4.35 g/cc). Ti-9S (or T-9S) has a density of 0.156 lb/in³(4.32 g/cc).

In other embodiments, the material may be another Î±-Î² Ti alloy, such as Ti-6-6-2, Ti-6246, or IMI 550. Titanium 662 may contain 6 wt % Al, 6 wt % V, and 2 wt % Sn, with the remaining alloy composition being titanium and possibly some trace elements. Ti-6-6-2 has a density of 0.164 lb/in3 (4.54 g/cc). The solvus temperature for Ti 662 is between 540Â° C. and 560Â° C. Titanium 6246 may contain 6 wt % Al, 2 wt % Sn, 4 wt % zirconium (Zr), and 6 wt % Mo, with the remaining alloy composition being titanium and possibly some trace elements. The solvus temperature for Ti 6246 is between 570Â° C. and 590Â° C. Ti-6246 has a density of 0.168 lb/in3 (4.65 g/cc). IMI 550 may contain 6 wt % Al, 2 wt % Sn, 4 wt % Mo, and 0.5 wt % Si, with the remaining alloy composition being titanium and possibly some trace elements. The solvus temperature for IMI 550 is between 490Â° C. and 510Â° C. IMI 550 has a density of 0.157 lb/in³(4.60 g/cc).

In other embodiments, the material may be another Î±-62 Ti alloy, such as Ti-8-1-1, which may contain 8 wt % Al, 1.0 wt % Mo, and 1 wt % V, with the remaining alloy composition being titanium and possibly some trace elements. In some embodiments, Ti-8-1-1 may contain 7.5 wt %-8.5 wt % Al, 0.75 wt %-1.25 wt % Mo., 0.75 wt %-1.25 wt % V, a maximum of 0.08 wt % C, a maximum of 0.3 wt % Fe, a maximum of 0.12 wt % O, a maximum of 0.05 wt % N, a maximum of 0.015 wt % H, a maximum of 0.015 wt % Sn, and trace amounts of Si, with the remaining alloy composition being titanium. The solvus temperature for Ti-8-1-1 is between 560Â° C. and 590Â° C. In some embodiments, Ti-8-1-1 has a density of 0.1580 lb/in³(4.37 g/cc).

FIG. 6 shows the process for forming for the club head assembly 30. In the first step 62, the faceplate 14 is aligned with respect to the club head 10. The second step 66 involves welding the faceplate 14 to the club head 10. In the third step 70, the club head 10 and the faceplate 14 are heated to a temperature at or above the solvus temperature of the faceplate 14 material. Finally, in the fourth step 74 the club head 10 and the faceplate 14 are air cooled.

In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 1 hour and 6 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 1 hour and 2 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 1 hour and 4 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 4 hours and 6 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 1.5 hours and 5.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 2 hours and 5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 2.5 hours and 4.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for between 3 hours and 4 hours in the third step 70.

In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 1 hour in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 1.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 2 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 2.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-Î² Ti alloy for at least 3 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 3.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 4 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 4.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 5.5 hours in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature at or above the solvus temperature of the Î±-62 Ti alloy for at least 6 hours in the third step 70.

In one embodiment, the club head assembly 30 is heat treated between 400Â° C. and 630Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated between 425Â° C. and 550Â° C. In one embodiment, the club head assembly 30 is heat treated between 450Â° C. and 525Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated between 550Â° C. and 625Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at 400Â° C., 410Â° C., 420Â° C., 430Â° C., 440Â° C., 450Â° C., 460Â° C., 470Â° C., 480Â° C., 490Â° C., 500Â° C., 510Â° C., 520Â° C., 530Â° C., 540Â° C., 550Â° C., 560Â° C., 570Â° C., 580Â° C., 590Â° C., 600Â° C., 610Â° C., 620Â° C., or 630Â° C. in the third step 70 for 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 210 minutes, 240 minutes, 270 minutes, 300 minutes, 330 minutes or 360 minutes.

In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 400Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 420Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 440Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 460Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 475Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 480Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 500Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 520Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 540Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 560Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 575Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 580Â° C. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 600Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 620Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 625Â° C. in the third step 70. In one embodiment, the club head assembly 30 is heat treated at a temperature of at least 630Â° C. in the third step 70.

In one embodiment, the club head assembly 30 is heat treated between 475Â° C. and 500Â° C. for between 4 hours and 6 hours in the third step 70. In another embodiment, the club head is heat treated between 575Â° C. and 625Â° C. for between 1 hour and 2 hours in the third step 70. In another embodiment, the club head is heat treated at about 550Â° C. for between 1 hour and 4 hours. In other embodiments, the face plate 14 may be formed from a different alloy in the third step 70. In other embodiments, the heat treatment process may be implemented at other temperatures for a different amount of time. In addition, the heat treatment may be applied to a variety of materials and a variety of weld-types.

Unlike conventional club head metal aging processes that occur at low temperature, heat-treating the club head assembly 30 above the solvus temperature after welding the faceplate 14 relieves stresses in the faceplate 14 and between the weld and the metal matrix of the club head 10. The post-weld stress relief disperses stresses associated with the weld-metal heat affected zone (HAZ), or the area around the weld in which the material properties have been altered due to the welding process. Because of the stark contrast in mechanical properties between the HAZ and the rest of the metal matrix, the HAZ is much more likely to experience a crack and fail. Previous post-weld treatments were performed below the solvus temperature for a short duration of time. These processes simply aged the metals, but did not address the increased stresses transferred to the weld area. Furthermore, the faceplate was not sufficiently strong and would flatten or lose its curvature relatively quickly. In contrast, the heat treatment above the solvus temperature disperses stresses in the weld metal HAZ. The heat-treatment improves the durability of the HAZ by relieving the stresses. In addition, heat-treating the club head assembly 30 above the solvus temperature reduces the possibility of generating titanium-aluminum (Ti₃A1) crystals along the weld.

The grains of the faceplate alloy may be aligned in a crown to sole orientation prior to heat treating. The crown to sole orientation of the alloy grains permits stretching in the same direction. In some embodiments, the grains of the faceplate Î±-62 titanium (Î±-Î² Ti) alloy may be aligned in a crown to sole orientation prior to heat treating. The crown to sole orientation of the Î±-62 Ti alloy grains permits stretching in the same direction. In some embodiments, the grains of the faceplate Ti-6Al-4V (or Ti 6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI 550 alloy may be aligned in a crown to sole orientation prior to heat treating. The crown to sole orientation of the Ti-6Al-4V (or Ti 6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI 550 alloy grains permits stretching in the same direction.

The heat treatment also improves the strength of the faceplate 14. The improved strength permits the faceplate 14 to be made thinner without sacrificing durability, thereby reducing club head weight. The reduced weight of faceplate 14 shifts the center of gravity of the club head assembly 30, and allows additional weight to be added to another component of the club to further adjust the center of gravity. Increasing the strength of the faceplate 14 also increases the durability of the faceplate 14, which permits the faceplate 14 to endure a significantly higher number of hits against a golf ball and maintain the faceplate's slightly bowed or rounded shape over the life of the club while sustaining hundreds or thousands of golf ball strikes. Therefore, the club is more forgiving when a ball is struck off-center because the rounded shape of the faceplate 14 provides a â€œgear effectâ€ between the ball and faceplate 14.

As shown in FIG. 7, an experiment was performed to compare the effect of various heat treatment temperatures on the faceplate 14 over the course of 2,000 hits or ball strikes. The faceplates 14 were formed from Ti-9S (or T-9S) alloy. One club head assembly was heated to 400Â° C., which is below the solvus temperature of the Ti-9S (or T-9S) alloy. A second club head assembly was heated to 600Â° C., which is above the solvus temperature of the Ti-9S (or T-9S) alloy. The measurement data provided in FIG. 7 represent the percent change in the radius of curvature of the bulge and the roll dimensions compared to the original radius curvature. As the faceplate becomes more flat, the radius of curvature increases. The club head assembly having a faceplate 14 with Ti-9S treated at 400Â° C. flattened significantly in both its roll and bulge dimensions within 25 hits on a golf ball. In contrast, the club head assembly having a Ti-9S faceplate treated at 600Â° C. maintained its curvature significantly better than the first club head assembly after 2,000 hits. The Ti-9S faceplate treated at 600Â° C. maintained its' curvature better after 2000 hits than the first club head assembly having a faceplate 14 of Ti-6-4 untreated maintained curvature in both roll and bulge dimensions.

For heat treatments below the solvus temperature (for example, at 400Â° C.), Ti₃A1 particles become more mobile and can precipitate into the a-matrix. Some of the Ti₃A1 particles gather at grain boundaries and age harden the material. In contrast, for heat treatments above the solvus temperature (for example, at 600Â° C.), Ti₃A1 particles instead dissolve within the Î±-matrix and relieve stresses within the material. The stress relief processes enables the club head assembly 30 to withstand tensile and compressive forces during impact against a golf ball.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 2 wt % of its original bulge and roll curvature after about 25 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 3 wt % of its original roll curvature and within 8 wt % of its original bulge curvature after about 25 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 8 wt % of its original bulge and roll curvature after about 50 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 5 wt % of its original roll curvature and within 10 wt % of its original bulge curvature after about 50 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 10 wt % of its original bulge and roll curvature after about 75 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 13 wt % of its original roll curvature and within 10 wt % of its original bulge curvature after about 75 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 10 wt % of its original bulge and roll curvature after about 100 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 14 wt % of its original roll curvature and within 10 wt % of its original bulge curvature after about 100 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 10 wt % of its original bulge and roll curvature after about 150 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 15 wt % of its original roll curvature and within l lwt % of its original bulge curvature after about 150 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 10 wt % of its original bulge and roll curvature after about 300 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 15 wt % of its original roll and bulge curvature after about 300 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 10 wt % of its original bulge and roll curvature after about 1,000 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 23 wt % of its original roll curvature and within 17 wt % of its original bulge curvature after about 1,000 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S) and heat treated above the solvus temperature of Ti-9S (or T-9S) remains within 10 wt % of its original bulge and roll curvature after about 2,000 strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4 and heat treated above the solvus temperature of Ti 6-4 remains within 24 wt % of its original roll curvature and within 18 wt % of its original bulge curvature after about 2,000 strikes.

Furthermore, an experiment was performed to compare the effect of various heat treatment temperatures on the faceplate 14 over the course of 2,000 hits or ball strikes. The faceplate 14 was formed from Î±-62 Ti alloy. One club head assembly was heated to 400Â° C., which is below the solvus temperature of the Î±-62 Ti alloy. A second club head assembly was heated to 600Â° C., which is above the solvus temperature of the Î±-62 Ti alloy. The club head assembly treated at 400Â° C. flattened significantly in both its roll and bulge dimensions within 25 hits on a golf ball. In contrast, the club head assembly treated at 600Â° C. did not begin to flatten until 225 strikes on a golf ball and maintained its curvature significantly better than the first club head assembly after 2,000 hits.

In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 25 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 50 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 75 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 100 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 125 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 150 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 175 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 200 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge and roll curvature after 225 hits.

In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 250 hits. In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 275 hits. In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 300 hits. In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 500 hits. In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 1,000 hits. In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 1500 hits. In one embodiment, the club head assembly treated at 600Â° C. substantially maintained its bulge and roll curvature after 2,000 hits.

In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge curvature and its roll curvature radius increased from 11 inches to 13 inches after 250 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its original bulge curvature and maintained a roll curvature radius of 13 inches after 275 hits. In one embodiment, the club head assembly treated at 600Â° C. increased its bulge curvature radius from 12 inches to 13 inches and maintained a roll curvature radius of 13 inches after 300 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its bulge curvature radius of 13 inches and maintained a roll curvature radius of 13 inches after 500 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its bulge curvature radius of 13 inches and increased its roll curvature radius from 13 inches to 14 inches after 1,000 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its bulge curvature radius of 13 inches and maintained a roll curvature radius of 14 inches after 1,500 hits. In one embodiment, the club head assembly treated at 600Â° C. maintained its bulge curvature radius of 13 inches and maintained a roll curvature radius of 14 inches after 2,000 hits.

Also, as shown in FIG. 8, a follow-up experiment was performed to compare the impact of a 600Â° C. heat treatment on three different faceplate geometries. The roll measurements for all three faceplate geometries were consistent, confirming that the stress-relief heat treatment increases the faceplate's ability to maintain its curvature. The faceplate comprised the Ti-9S (or T-9S) alloy.

Referring now to FIG. 9, an experiment was performed to compare the effect of various heat treatment temperatures on the faceplate 14 over the course of 2,000 hits or ball strikes. The faceplates 14 were formed from Ti-9S (or T-9S) alloy. One club head assembly was heated to 550Â° C., which is below the solvus temperature of the Ti-9S (or T-9S) alloy. A second club head assembly was heated to 575Â° C. and a third club head was heated to 600Â° C., which is above the solvus temperature of the Ti-9S (or T-9S) alloy. The measurement data provided in FIG. 9 represent the percentage change in the radius of curvature of the bulge and the roll dimensions compared to the original radius curvature. As the faceplate becomes more flat, the radius of curvature increases. The club head assembly treated at 550Â° C. flattened significantly in both its roll and bulge dimensions within a few hits on a golf ball. In contrast, the club head assembly treated at 600Â° C. maintained its curvature significantly better than the club head assemblies after 2,000 hits.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. remains within 1 wt % of its original roll curvature and within 3 wt % of its original bulge curvature after 25 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 24 wt % of its original roll curvature and within 11 wt % of its original bulge curvature after 25 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 19 wt % of its original roll curvature and within 9 wt % of its original bulge curvature after 25 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. retains its original roll curvature and is within 4 wt % of its original bulge curvature after 50 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 28 wt % of its original roll curvature and within 13 wt % of its original bulge curvature after 50 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 23 wt % of its original roll curvature and within 15 wt % of its original bulge curvature after 50 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. retains its original roll curvature and is within 5 wt % of its original bulge curvature after 75 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 28 wt % of its original roll curvature and within 12 wt % of its original bulge curvature after 75 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 28 wt % of its original roll curvature and within 23 wt % of its original bulge curvature after 75 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. retains its original roll curvature and is within 6 wt % of its original bulge curvature after 100 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 30 wt % of its original roll curvature and within 13 wt % of its original bulge curvature after 100 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 29 wt % of its original roll curvature and within 22 wt % of its original bulge curvature after 100 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. retains its original roll curvature and is within 7 wt % of its original bulge curvature after 150 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 28 wt % of its original roll curvature and within 13 wt % of its original bulge curvature after 150 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 31 wt % of its original roll curvature and within 24 wt % of its original bulge curvature after 150 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. remains within 5 wt % of its original roll curvature and within 5 wt % of its original bulge curvature after 300 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 28 wt % of its original roll curvature and within 14 wt % of its original bulge curvature after 300 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 34 wt % of its original roll curvature and within 26 wt % of its original bulge curvature after 300 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. remains within 4 wt % of its original roll curvature and within 7 wt % of its original bulge curvature after 1,000 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 27 wt % of its original roll curvature and within 13 wt % of its original bulge curvature after 1,000 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 34 wt % of its original roll curvature and within 27 wt % of its original bulge curvature after 1,000 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 600Â° C. remains within 5 wt % of its original roll curvature and within 6 wt % of its original bulge curvature after 2,000 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 575Â° C. remains within 25 wt % of its original roll curvature and within 15 wt % of its original bulge curvature after 2,000 strikes. In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heat treated at 550Â° C. remains within 34 wt % of its original roll curvature and within 28 wt % of its original bulge curvature after 2,000 strikes.

As shown in FIG. 10, an experiment was performed to compare the durability of faceplate 14 when composed of either the Ti-6-4 alloy or the Ti-9S (T-9S) alloy. The experiment tracked the number of strikes from an air cannon until failure of the faceplate 14. One club head assembly used Ti 6-4 alloy as the faceplate material. A second club head assembly used a different model club head with Ti 6-4 alloy as the faceplate material (data not shown). A third club head assembly used a third model club head with the Ti 6-4 alloy as the faceplate material (data not shown). A fourth club head assembly uses the same model club head as the third club head assembly, with T-9S (or Ti-9S) alloy as the faceplate material. The measurement data provided in FIG. 10 represents the number of hits until failure of the faceplate. The club head assembly with the T-9S (or Ti-9S) alloy faceplate showed increased durability over assemblies with Ti 6-4 alloy faceplates. The same club head model showed an increased durability of about 3200 hits until failure of the faceplate with T-9S (or Ti-9S) alloy as the faceplate material, as opposed to a durability of 2600 hits until failure with Ti 6-4 alloy as the faceplate material.

Thus, the invention provides, among other things, a method of forming a golf club head assembly. Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.

Clause 1. A method of forming a golf club head assembly, the method comprising:

- (a) providing a faceplate formed from an Î±-62 titanium alloy, the Î±-62 titanium alloy comprising between 2 wt % to 10 wt % aluminum (Al);
- (b) aligning the faceplate with a recess of a club head;
- (c) welding the faceplate to the club head;
- (d) heating the club head and the faceplate to a temperature that is greater than the solvus temperature of the faceplate for a predetermined amount of time; and
- (e) allowing the club head and the faceplate to cool in an inert gas, wherein step (d) is performed at a temperature of at least 580Â° C.

Clause 2. The method of clause 1, wherein the Î±-62 titanium alloy comprising between 6.5 wt % to 10 wt % aluminum.

Clause 3. The method of clause 1, wherein the Î±-62 titanium alloy further comprises 1.0 wt % to 2.0 wt % vanadium (V), 0.20 wt % or less oxygen (O), and 0.20 wt % or less silicon (Si);.

Clause 4. The method of clause 3, wherein the Î±-62 titanium alloy further comprises 0.30 wt % or less iron (Fe), 0.08 wt % or less carbon (C), 0.05 wt % or less nitrogen (N), trace molybdenum (Mo), trace tin (Sn), and the remaining weight percent is titanium (Ti).

Clause 5. The method of clause 1, wherein the welding of step (c) includes a pulse plasma welding process.

Clause 6. The method of clause 1, wherein the inert gas of step (e) is selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe) or a compound gas thereof.

Clause 7. The method of clause 6, wherein the inert gas is nitrogen (N) or argon (Ar).

Clause 8. The method of clause 1, wherein the faceplate of step (a) has a minimum thickness of 0.7 mm.

Clause 9. The method of clause 1, wherein step (d) includes heating the club head and the faceplate between 550Â° C. and 625Â° C. for between 1 hour and 2 hours.

Clause 10. The method of clause 9, wherein heating the club head and the faceplate includes heating the club head and the faceplate to between 575Â° C. and 625Â° C. for between 1 hour and 2 hours.

Clause 11. A method of forming a golf club head assembly, the method comprising:

- (a) providing a faceplate formed from an Î±-62 titanium alloy, the alloy having a solvus temperature;
- (b) aligning the faceplate with a recess of a club head;
- (c) welding the faceplate to the club head;
- (d) heating the club head and the faceplate to a temperature that is greater than the solvus temperature of the faceplate for a predetermined amount of time; and
- (e) allowing the club head and the faceplate to cool in an inert gas,
- wherein the club head assembly substantially maintains its bulge and roll curvature after 2,000 golf ball strikes.

Clause 12. The method of clause 11, wherein the faceplate remains within 10% of its original bulge and roll curvature after about 2,000 golf ball strikes.

Clause 13. The method of clause 11, wherein the faceplate remains within 5% of its original roll curvature and within 6% of its original bulge curvature after 2,000 golf ball strikes.

Clause 14. The method of clause 11, wherein the faceplate exhibits about 3,200 hits until failure, assessed by tracking the number of golf ball strikes from an air cannon until failure.

Clause 15. The method of clause 11, wherein the club head and the faceplate are heated to a temperature that is greater than the solvus temperature of the faceplate for at least one hour.

Clause 16. The method of clause 11, wherein the club head and the faceplate are heat treated at a temperature of at least 580Â° C.

Clause 17. The method of clause 11, wherein the Î±-62 titanium alloy comprises between 2 wt % to 10 wt % aluminum (Al).

Clause 18. The method of clause 11, wherein the Î±-62 titanium alloy comprises between 6.5 wt % to 10 wt % aluminum (Al).

Clause 19. The method of clause 11, wherein the faceplate of step (a) has a minimum thickness of 0.7 mm.

Clause 20. A method of dispersing stresses in the weld-metal heat affected zone (HAZ) of a faceplate welded to a golf club head, the method comprising:

- (a) heating the club head and the faceplate to a temperature that is greater than the solvus temperature of the faceplate for a predetermined amount of time;
  wherein the faceplate is formed from an Î±-62 titanium alloy, the Î±-62 titanium alloy comprising between 6.5 wt % to 8.5 wt % aluminum (Al), 1.0 wt % to 2.0 wt % vanadium (V), 0.20 wt % or less oxygen (O), and 0.20 wt % or less silicon (Si).