A METHOD FOR CONSTRUCTING A MULTIPLE PIECE

GOLF CLUB HEAD (Corporate Docket Number PU2624)

Technical Field

[0001] The present invention relates to manufacturing golf club heads . More specifically, the present invention relates to manufacturing multiple piece golf club heads.

Background Art

[0002] Most conventional all metal golf club heads are manufactured using a cast titanium body with a sheet metal face insert. The major disadvantage of the cast face insert manufacturing method is the amount of casting stock that is wasted in casting a 460 cubic centimeters ("cc") golf club head (as shown in FIG. 6), and the fact that the center of gravity ("CG") consistency from the computer assisted drawing ("CAD") to the finished part is poor.

[0003] Another process involves a forged face cup with a sheet metal crown, sheet metal sole and hosel tube. The major disadvantage of this process is the performance and controlling the volume near 460cc may be difficult.

[0004] Some low quality drivers are composed of four pieces involving a sheet metal crown, sheet metal sole, sheet metal face and a hosel tube. The major disadvantage of this four piece method is the lower performance, lack of CG consistency, lack of characteristic time ("CT"), durability issues, and controlling the volume.

Summary of the Invention

[0005] One aspect is a method for manufacturing a golf club head. The method includes generating a CAD net size for the golf club head and the components of the golf club head. The components preferably comprise a

face component, a crown component, and a sole component. The method also includes forming the face component with the face component substantially matching the CAD net size. The face component preferably comprises a striking plate portion, a return portion and a hosel having a bore. The method also includes reaming the bore of the hosel to ensure a predetermined loft angle and lie angle for the golf club head to create a reamed face component. The method also includes forming the crown component with the crown component substantially matching the CAD net size. The method also includes forming the sole component with the sole component substantially matching the CAD net size. The method also includes tacking the crown component to the sole component to create a tacked aft-body. The method also includes tacking the tacked aft- body to the reamed face component to create a tacked golf club head. The method also includes welding the tacked golf club head to create a welded golf club head. The method also includes grinding the welded golf club head to create a ground golf club head. The method also includes finishing the ground golf club head to create a finished golf club head.

[0006] Another aspect is method for assembling a golf club head. The method includes providing a face component, a sole component and a crown component. The face component preferably comprises a striking plate section, a return section and a hosel. The method also includes tacking the crown component to the sole component to create a tacked aft- body. The method also includes tacking the tacked aft-body to the face component to create a tacked golf club head. The method also includes welding the tacked golf club head to create a welded golf club head.

[0007] The method disclosed reduces the cost of a large (near 460cc) titanium driver-type golf club head without sacrificing performance and durability.

[0008] For example, casting a 460cc driver body with very thin walls creates a lot of scrap titanium material. In a multi-piece format utilized in the method

disclosed, the thin walls are created using sheet material and scrap is much less than a casting process. In a multi-piece format utilized in the method disclosed, a face component is preferably cast, however more face components are used on a single casting tree than entire 460cc club head bodies, hi alternative embodiments the face component is formed by forging or a pressed sheet metal.

[0009] Specific performance aspects are preferably managed through different features of the method disclosed.

[0010] CT and durability are preferably managed by utilizing a face component design that includes the face to body transition geometry (the portion of the body that transitions into the face around the face). CT is more consistent by not having the weld directly at the face to body transition as in a prior art four-piece construction. Durability is higher and more consistent for a similar reason as CT such as by positioning the weld area away from the high stresses of the face to body transition corner.

[0011] The volume of the golf club head is managed in multiple ways. One way is by ensuring that the body and face component are formed "net" to CAD without reverse engineering. The method disclosed has the body and face component fit to each other on every set of components without using the tacking and a manual fitting process currently used on conventional four- piece and forged face cup assembly processes.

[0012] Another manner in which the volume of the golf club head is managed is the very close fit of the components (precision trimmed parts), which preferably results in butt welds at all intersections. This allows joints to be welded without having them pull or distort during the heating and cooling of welding. Another manner in which the volume of the golf club head is managed is precisely forming the sheet metal parts, which allows the parts to be fit together prior to tacking them to the face component.

[0013] Welding consistency is another benefit from the sheet metal aft-body created by tacking the crown and sole together. Welding consistency is

achieved since the weld joints are much more consistent than on manually fit crown to sole components. Weld consistency is key for numerous reasons including consistent joints that allow for semi or fully automated welding to be incorporated into the method.

[0014] The method allows for the butt joints to be welded using a plasma welding method or laser welding method which is typically easier to automate than conventional TIG welding. Automated plasma welding methods are generally faster than manual TIG welding, thus increasing throughput and potentially offering cost benefits. Consistent joints provide for more consistent welds, such that the added mass at the weld line is also easier to manage. The result of the method is a more consistent CG position of the golf club head than in conventional four-piece construction methods.

[0015] The method allows for face angle consistency to be managed without having to manually check and iterate the angle of the sole to the face or face component on each head. In a conventional four-piece construction and other face component assembly methods, the first two components combined are the face and the sole. The angle of the face to the sole then directly affects the face angle of the finished golf club head.

[0016] A resultant of forming well fitting, net components (face component, crown, and sole) is better management of the final CG positioning within a golf club head as compared to the original CAD data (specifically compared to cast body methods). The CG is managed by controlling the aft-body thickness. For the method, the crown and sole components are rolled to a tight tolerance prior to forming (+/-0.0015 inch). In conventional castings, there are many factors that will determine the 'raw' unfinished crown thickness such as actual tool fabrication, tool benching, tool to tool variation, shell expansion issues, shrink issues, and finishing. The fit management using precision trimmed and net components in the method provides CG management by ensuring the golf club head is not too large or small. Typically, a conventional casting requires more thickness removal during the

finishing operations, which moves the CG more than using the method disclosed, especially with a grinding process that is not very tightly controlled for thickness and weight.

[0017] In the multi-piece construction method disclosed, the different components are preferably composed of different alloys. In a typical cast titanium body for a driver golf club head, there are very few alloys that can be used for casting. It is typical to use 6-4 titanium alloy since it has the appropriate strength characteristics and can be cast relatively thin. Thinner castings result in more issues with costly casting rejects, porosity, poor mold fill and the like. A sheet metal aft-body of the method disclosed allows the crown and sole components to be made from different alloys. The alloy choice is preferably made to manage different aspects such as cost, durability, performance and the like.

[0018] With high quality forming and precision sheet components, it is easier to achieve consistently thin crowns than in casting. Combined with alloy selection (using 15-3-3-3 alloy for the crown component), the crown component is greatly reduced in thickness compared to cast crowns. Further, the field durability of the crown component is increased with the method disclosed. The saved discretionary mass is used to specify the CG position, increase the moment of inertia ("MOI") or both.

Brief Description of the Drawings [0019] FIG. 1 is an exploded view of a golf club head. [0020] FIG. 2 is an isolated perspective view of a sole component and a weight chip component. [0021] FIG. 3 is an isolated perspective view of a tacked body having a crown component tacked to a sole component with a weight chip component. [0022] FIG. 4 is a perspective view of a tacked body and a face component.

[0023] FIG. 5 is a perspective view of a tacked golf club head.

[0024] FIG. 6 is a graph of raw material usage in grams.

[0025] FIG. 7 is a flow chart of a specific method for manufacturing a golf club head. [0026] FIG. 8 is a flow chart of a general method for assembling a golf club head.

Best Mode(s) For Carrying Out The Invention

[0027] As shown in FIG. 1 , a golf club head 20 generally comprises a face component 25, a crown component 30, a sole component 35 and a weight chip component 40.

[0028] The golf club head 20, when designed as a driver, preferably has a volume from 200 cubic centimeters to 600 cubic centimeters, more preferably from 300 cubic centimeters to 500 cubic centimeters, and most preferably from 420 cubic centimeters to 470 cubic centimeters, with a most preferred volume of 460 cubic centimeters. The volume of the golf club head 20 will also vary between fairway woods (preferably ranging from 3 -woods to eleven woods) with smaller volumes than drivers.

[0029] The golf club head 20, when designed as a driver, preferably has a mass no more than 215 grams, and most preferably a mass of 180 to 215 grams. When the golf club head 20 is designed as a fairway wood, the golf club head 20 preferably has a mass of 135 grams to 200 grams, and preferably from 140 grams to 165 grams.

[0030] The face component 25 is generally composed of a single piece of metal, and is preferably composed of a cast or coined metal material. More preferably, the cast or coined metal material is a titanium alloy material. Such titanium materials include titanium alloys such as 6-4 titanium alloy, SP-700 titanium alloy (available from Nippon Steel of Tokyo, Japan), DAT 55G titanium alloy available from Diado Steel of Tokyo, Japan, Ti 10-2-3 Beta-C titanium alloy available from RTI

International Metals of Ohio, and the like. Other metals for the face component 25 include stainless steel, other high strength steel alloy metals and amorphous metals. Alternatively, the face component 25 is manufactured through forging, machining, powdered metal forming, metal-injection-molding, electro chemical milling, and the like.

[0031] The face component 25 generally includes a striking plate portion (also referred to herein as a face plate) and a return portion extending laterally inward from a perimeter of the striking plate portion. The striking plate portion preferably has a plurality of scorelines thereon. The striking plate portion preferably has a thickness ranging from 0.010 inch to 0.250 inch, and the return portion preferably has a thickness ranging from 0.010 inch to 0.250 inch. The return portion preferably extends a distance ranging from 0.25 inch to 1.5 inches from the perimeter of the striking plate portion.

[0032] In a preferred embodiment, the return portion generally includes an upper lateral section, a lower lateral section, a heel lateral section and a toe lateral section. Thus, the return preferably encircles the striking plate portion a full 360 degrees. However, those skilled in the pertinent art will recognize that the return portion may only encompass a partial section of the striking plate portion such as 270 degrees or 180 degrees, and may also be discontinuous.

[0033] The upper lateral section preferably extends inward, towards the aft-body, a predetermined distance to engage the crown. In a preferred embodiment, the predetermined distance ranges from 0.2 inch to 1.2 inch, more preferably 0.40 inch to 1.0 inch, and most preferably 0.8 inch, as measured from the perimeter of the striking plate portion to the rearward edge of the upper lateral section. In a preferred embodiment, the upper lateral section is substantially straight and substantially parallel to the striking plate portion from the heel end to the toe end. The perimeter of the striking plate portion is preferably defined as the transition point

where the face component 25 transitions from a plane substantially parallel to the striking plate portion to a plane substantially perpendicular to the striking plate portion. Alternatively, one method for determining the transition point is to take a plane parallel to the striking plate portion and a plane perpendicular to the striking plate portion, and then take a plane at an angle of forty-five degrees to the parallel plane and the perpendicular plane. Where the forty-five degrees plane contacts the face component is the transition point thereby defining the perimeter of the striking plate portion,

[0034] The heel lateral section is substantially perpendicular to the striking plate portion and the heel lateral section preferably covers a portion of the hosel before engaging an optional ribbon section and a bottom section of the sole portion of the aft-body. The heel lateral section is attached to the sole portion, both the ribbon section and the bottom section. The heel lateral section extends inward a distance from the perimeter a distance of 0.2 inch to 1.2 inch, more preferably 0.40 inch to 1.0 inch, and most preferably 0.8 inch. The heel lateral section is preferably straight at its edge.

[0035] At the other end of the face component 25 is the toe lateral section. The toe lateral section is preferably attached to the sole component 35. The toe lateral section extends inward a distance from the perimeter a distance of 0.2 inch to 1.2 inch, more preferably 0.40 inch to 1.0 inch, and most preferably 0.8 inch. The toe lateral section preferably is preferably straight at its edge.

[0036] The lower lateral section extends inward, toward the aft-body, a distance to engage the sole component 35. In a preferred embodiment, the distance ranges from 0.2 inch to 1.2 inch, more preferably 0.40 inch to 1.0 inch, and most preferably 0.8 inch, as measured from the perimeter of the striking plate portion to the edge of the lower lateral section.

[0037] The face component preferably as a striking plate portion with

varying thickness. In a preferred embodiment, the striking plate portion has a varying thickness such as described in U. S Patent Number 6398666, for a Golf Club Striking Plate With Variable Thickness, which pertinent parts are hereby incorporated by reference. Other alternative embodiments of the thickness of the striking plate portion are disclosed in U.S. Patent Number 6471603, for a Contoured Golf Club Face and U.S. Patent Number 6368234, for a Golf Club Striking Plate Having Elliptical Regions Of Thickness, which are both owned by Callaway Golf Company and which pertinent parts are hereby incorporated by reference. Alternatively, the striking plate portion has a uniform thickness.

[0038] Alternatively, the face component 25 is composed of an amorphous metal material such as disclosed in U.S. Patent Number 6471604, which is hereby incorporated by reference in its entirety.

[0039] In a preferred embodiment, the golf club head 20 has a high coefficient of restitution thereby enabling for greater distance of a golf ball hit with the golf club. The coefficient of restitution (also referred to herein as "COR") is determined by the following equation: e = v±→i

U ₁ -U ₂

[0040] wherein Uj is the club head velocity prior to impact; £/_• is the golf ball velocity prior to impact which is zero; vj is the club head velocity just after separation of the golf ball from the face of the club head; v _∑ is the golf ball velocity just after separation of the golf ball from the face of the club head; and e is the coefficient of restitution between the golf ball and the club face.

[0041] The values of e are limited between zero and 1.0 for systems with no energy addition. The coefficient of restitution, e, for a material such as a soft clay or putty would be near zero, while for a perfectly elastic material, where no energy is lost as a result of deformation, the value of e

would be 1.0. The present invention provides a club head having a coefficient of restitution ranging from 0.81 to 0.94, as measured under conventional test conditions.

[0042] The coefficient of restitution of the club head 20 under standard USGA test conditions with a given ball ranges from approximately 0.81 to 0.94, preferably ranges from 0.825 to 0.883 and is most preferably 0.845.

[0043] Additionally, the striking plate portion of the face component 25 has a more rectangular face providing a greater aspect ratio. The aspect ratio as used herein is defined as the width, "W", of the face divided by the height, "H", of the face. In one preferred embodiment, the width W is 100 millimeters and the height H is 56 millimeters giving an aspect ratio of 1.8. The striking plate portion of the present invention preferably has an aspect ratio that is greater than 1.8 for a club head having a volume greater than 420 cubic centimeters.

[0044] The face area of the striking plate portion preferably ranges from 5.00 square inches to 10.0 square inches, more preferably from 6.0 square inches to 9.5 square inches, and most preferably from 7.0 square inches to 9.0 square inches.

[0045] The axes of inertia are designated X, Y and Z. The X-axis extends from the striking plate portion through the center of gravity, CG, and to the rear of the golf club head 42. The Y-axis extends from the toe end of the golf club head 20 through the center of gravity, CG, and to the heel end of the golf club head 20. The Z-axis extends from the crown component 30 through the center of gravity, CG, and through the sole component 35.

[0046] As defined in Golf Club Design, Fitting, Alteration & Repair, 4 ^th Edition, by Ralph Maltby, the center of gravity, or center of mass, of the golf club head is a point inside of the club head determined by the vertical intersection of two or more points where the club head balances when suspended. A more thorough explanation of this definition of the center

of gravity is provided in Golf Club Design, Fitting, Alteration & Repair.

[0047] The center of gravity and the moment of inertia of a golf club head 20 are preferably measured using a test frame (X ^τ , Y ^τ , Z ^τ ), and then transformed to a head frame (X ^H , Y ^H , Z ^H ). The center of gravity of a golf club head may be obtained using a center of gravity table having two weight scales thereon, as disclosed in U.S. Patent Number 6607452, entitled High Moment Of Inertia Composite Golf Club, and hereby incorporated by reference in its entirety. If a shaft is present, it is removed and replaced with a hosel cube that has a multitude of faces normal to the axes of the golf club head. Given the weight of the golf club head, the scales allow one to determine the weight distribution of the golf club head when the golf club head is placed on both scales simultaneously and weighed along a particular direction, the X, Y or Z direction. Those skilled in the pertinent art will recognize other methods to determine the center of gravity and moments of inertia of a golf club head.

[0048] In general, the moment of inertia, Izz, about the Z axis for the golf club head 20 of the present invention will range from 3500g-cm ² to 6000g-cm ² , preferably from 4000g-cm ² to 5000g-cm ² , and most preferably from 4200g-cm ² to 4750g-cm ² . The moment of inertia, Iyy, about the Y axis for the golf club head 20 of the present invention will range from 2000g-cm ² to 4000g-cm ² , preferably from 2500g-cm ² to 3500g-cm ² , and most preferably from 2900g-cm ² to 3300g-cm ² . The moment of inertia, Ixx, about the X axis for the golf club head 20 of the present invention will range from 2000g-cm ² to 4000g-cm ² , preferably from 2500g-cm ² to 3750g-cm ² , and most preferably from 3000g-cm ² to 3500g-cm ² .

[0049] In general, the golf club head 20 has products of inertia such as disclosed in U.S. Patent Number 6425832, which is hereby incorporated by reference in its entirety. Preferably, each of the products of inertia, Ixy, Ixz and Iyz, of the golf club head 20 have an absolute value less than 100

grams-centimeter squared. Alternatively, at least two of the products of inertia, Ixy, Ixz or Iyz, of the golf club head 20 have an absolute value less than 100 grams-centimeter squared.

[0050] A specific method 700 for manufacturing a golf club head is shown in FIG. 7. At block 701, the method begins with generating a CAD net size for a golf club head and the components of the golf club head. The components include a face component, a crown component, a sole component and a weight chip component.

[0051] At block 702, the face component is formed. The face component substantially matches the CAD net size. The face component includes a striking plate portion, a return portion and a hosel having a bore.

[0052] At block 703, the bore of the hosel is reamed to ensure a predetermined loft angle and lie angle for the golf club head, resulting in a reamed face component.

[0053] At block 704, the crown component, the sole component and the weight component are formed. Each of the crown component and the sole component substantially matches the CAD net size. For example, the crown and sole components may be formed from a sheet of titanium material that is first rolled to a tight tolerance (+/-0.0015 inch) prior to forming. The formed components are precision trimmed, and the net components help tighten any variation in the resulting golf club head's center of gravity from the CAD specifcations. The weight chip component also substantially matches the CAD net size.

[0054] At block 705, the weight chip component is tacked to an internal surface of the sole component to create a tacked weight component, as shown in FIG. 2.

[0055] At block 706, the tacked weight component is welded to the internal surface of the sole component to create a welded sole component.

[0056] At block 707, the crown component is tacked to the welded sole

component to create tacked aft-body, as shown in FIG. 3. [0057] At block 708, the tacked aft-body is tacked to the reamed face component to create a tacked golf club head. [0058] At block 709, the tacked golf club head is welded to create a welded golf club head. [0059] At block 710, the welded golf club head is ground to create a ground golf club head. [0060] At block 711, the ground golf club head is finished to create a finished golf club head. [0061] A flow chart for a general method 800 for assembling a golf club head is shown FIG. 8. At block 801 , a face component, a sole component and a crown component are provided for assembly. The face component includes a striking plate section, a return section and a hosel. Each of these components is preferably made to net to its CAD specifications, so that any grinding, bending or tweaking of the components to get them to fit together is eliminated. [0062] At block 802, the crown component is tacked to the sole component to create tacked aft-body. [0063] At block 803, the tacked aft-body is tacked to the face component to create a tacked golf club head. [0064] At block 804, the tacked golf club head is welded to create a welded golf club head. [0065] Each of the components preferably is composed of titanium alloy.

More specifically, the face component is preferably composed of cast titanium alloy. The sole component and the crown component are preferably composed of a sheet-formed titanium alloy. [0066] Alternatively, the face component is preferably composed of coined titanium alloy. The sole component and the crown component are preferably composed of a sheet-formed titanium alloy. [0067] Alternatively, the face component is preferably composed of

forged titanium alloy. The sole component and the crown component are preferably composed of a sheet-formed titanium alloy.

[0068] The finished golf club head preferably has a volume ranging from 450cc to 475cc, and more preferably from 455cc to 465cc. The finished golf club head preferably has a mass ranging from 175 grams to 224 grams, and more preferably from 190 grams to 210 grams. The weight chip component preferably has a mass ranging from 5 grams to 30 grams.

[0069] The finished golf club head preferably has a moment of inertia, Iyy, about the center of gravity of the finished golf club head greater than 2000 grams-centimeters squared and a moment of inertia, Izz, about the center of gravity of the finished golf club head greater than 3000 grams- centimeters squared.

[0070] More preferably, the finished golf club head has a moment of inertia, Iyy, about the center of gravity of the finished golf club head greater than 2000 grams-centimeters squared and a moment of inertia, Izz, about the center of gravity of the finished golf club head greater than 4000 grams-centimeters squared.