Metal working – Method of mechanical manufacture – Providing transitory integral holding or handling portion
Reexamination Certificate
1996-07-30
2001-10-23
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Providing transitory integral holding or handling portion
C029S445000, C029S558000, C473S345000, C473S305000
Reexamination Certificate
active
06305063
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to golf clubs and their manufacture, and is particularly concerned with golf clubs of the so-called “metalwood” type.
Golf clubs are generally divided into four main types, comprising putters, irons, fairway clubs and drivers. Drivers in the past were normally made of wood, and so were often referred to as “woods”. More recently, drivers have been made of metal and so are often now called metalwoods.
Most metalwoods are conventionally made of stainless steel, and with very few exceptions they are manufactured by investment casting a hollow stainless steel shell. The investment cast process can be inconsistent, and the golf club has a face which can be inconsistent and can contain sinks. It must be polished and is normally cosmetically sand blasted to hide its imperfections. When investment casting thin wall stainless steel heads, a large number of rejections result due to porosity and thin spots. The investment casting process itself is expensive, involving high tooling expenses, and the results are inconsistent.
Stainless steel is relatively heavy and thus the walls of the club head must be made relatively thin in order to maintain an acceptable club head weight. Since the skin is relatively thin, relatively high amounts of club face deflection occur when the club head strikes the ball, resulting in inconsistent performance.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new and improved metalwood golf club head and a new and improved method of making such a golf club.
According to one aspect of the present invention, a golf club head is provided which comprises a hollow body having a front striking face, a heel, a toe, an upper wall or crown, a lower wall or sole, and a rear wall, the body being made in one piece from forged material with an internal cavity milled out through the lower wall. A separate sole plate may be secured in a machined recess in the lower face of the body, at least the body being of forged aluminum alloy or high density nonmetallic material with physical characteristics equivalent to aluminum alloy, the striking face being machined or milled to have a predetermined bulge and roll, and having a thickness of at least more than 0.125 inches thick. Preferably, the heel has a bore projecting inwardly from the upper wall into the heel and terminating within the heel, the bore comprising means for receiving a hosel and being oriented to determine the desired face angle and lie angle.
Because the club head is fabricated from a single, solid billet of forged material, it is possible to incorporate any desired face angle, lie, weight distribution or other parameters at the time of manufacture using the same basic cutting tools. The disadvantages of cast and welded club heads are thereby avoided, and the club head is significantly improved in performance. Due to the lightweight material used, and the manufacture from a single, solid billet of material, the club head can be designed to have the playing characteristics of a true wood club head, for example enhanced gear effect, which generally cannot be achieved in a large cast stainless steel head due to weight limitations. At the same time, the forged metal wood does not experience as much loss of distance as do wood heads when struck off center, and has reduced susceptibility to damage such as splitting and chipping.
Due to the lower weight of aluminum alloy as compared to stainless steel, the shell walls can be made thicker and therefore stronger than a stainless steel metalwood, while still maintaining the desired club head weight as required for men's or ladies' clubs. The alloy is preferably 6061 T6 or 7075 T6 aluminum alloy of the type which has up to now been used mainly in the aircraft industry.
Since the shell or body walls do not have to be kept to a minimum thickness to meet weight requirements, additional material may be distributed about the shell in order to adjust the club head performance properties as desired. For example, extra weight may be used at the toe and heel to produce a larger sweet spot. Extra weight may be provided at the rear wall to move the center of gravity away from the club face. This produces an enhanced “gear effect” when a ball is struck away from the center of the club face. The enhanced gear effect can be a help both to an average golfer who does not always strike the ball at the center of the club face, and to a professional who likes to be able to control the flight of the ball more accurately. The center of gravity is preferably positioned at an equivalent spot to that of a persimmon wood, about halfway between the front and rear face of the club.
According to another aspect of the present invention, a method of making a metalwood golf club head is provided, which comprises the steps of forming a solid billet of aluminum material having an upper face, a lower face, a front end, and a rear end, and milling out the lower face to form a cavity of predetermined dimensions. A sole plate receiving recess is machined on the lower face surrounding the cavity, a sole plate is secured in the recess, and the front end is machined to form a ball striking face of predetermined bulge and roll.
Preferably, the billet is forged with a projecting lug which is used to hold the billet while machining the cavity and sole plate recess. The billet and secured sole plate may be machined together to form continuous heel, toe and rear walls of the head, and the billet may then be held at a different position before machining off the lug to form a striking face of predetermined bulge and roll.
The machining steps are preferably performed in a computer controlled milling machine or CNC machine. This permits machining to very precise tolerances, resulting in improved accuracy in the finished club head. Club heads manufactured by this method will consistently meet design specifications, and the specifications can be easily varied to conform to different design parameters. The club head is machined both externally and internally by the computerized milling machine process, resulting in a high precision product with essentially no distortions.
The club head which is fabricated from a forged billet of high strength aluminum alloy will be strong, consistent in performance, and will have far superior strength, performance and rigidity as compared with a conventional stainless steel metalwood.
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Ashcraft Danny C.
Cruz Richard De La
Parente Richard E.
Bryant David P.
Danny Ashcraft
Gray Cary Ware & Freidenrich
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