Golf club head with increased radius of gyration and face reinforcement

Abstract

An improved high impact metal clubhead with a unique reinforced composite face wall, increased radius of gyration, and a positive lift air foil surface contour. The composite face wall includes an impact supporting wall rigidified by a pattern of integrally cast reinforcing bars that extend forwardly, rather than rearwardly, from the supporting wall. The reinforced supporting wall is covered by a very hard plastic ball striking insert that is cast in situ over the supporting wall. The increase in radius of gyration is accomplished by extending the heel and toe portions of the clubhead along the face wall further from the geometric center of the head, beyond present day parameters for high impact clubheads. And the positive lift is effected by contouring the top wall of the clubhead downwardly and rearwardly from the base wall more severely almost to the plane of the sole plate, and flattening the rear wall so it is almost co-planar with the sole plate. This configuration results in the top wall being equal to or greater in length than the combined length of the sole plate and rear wall in a vertical plane extending through the clubhead along the target line. The laws of continuity of matter and the air foil shape of the top wall eliminate the negative lift or drag in today's "woods" and offer the possibility of some positive lift to increase ball overspin.

Description

BACKGROUND OF THE INVENTIONInvestment casting techniques innovated in the late 1960s have revolutionized the design, construction and performance of golf clubheads up to the present time Initially only novelty putters and irons were investment cast, and it was only until the early years of the 1980s that investment cast metal woods achieved any degree of commercial success. The initial iron clubheads that were investment cast in the very late 1960s and early 1970s innovated the cavity backed clubheads made possible by investment casting which enabled the molder and tool designer to form rather severe surface changes in the tooling that were not possible in prior manufacturing techniques for irons which were predominantly at that time forgings. The forging technology was expensive because of the repetition of forging impacts and the necessity for progressive tooling that rendered the forging process considerably more expensive than the investment casting process and that distinction ...

AI Technical Summary

Benefits of technology

In accordance with the present invention, an improved high impact metal clubhead is provided with a unique composite face wall, increased radius of gyration, and a positive lift air foil contour.

Toward these ends, the composite face wall includes an impact supporting wall that is investment cast with the remainder of the head(without the sole plate which is a separate piece as cast). This impact supporting wall is rigidified by a pattern of integrally cast reinforcing bars that extend forwardly from the forward wall rather than rearwardly as described in the above discussed Raymont and Allen patents. This reinforcing pattern has a depth of approximately 0.150 inches which is significantly greater than reinforcing patterns possible on the rear of the ball striking faces of prior constructions. This increased depth provides far greater supporting wall reinforcement. It is also easily cast because the core piece that forms these deep depth reinforcing elements are removed by a direct forward withdrawal unencumbered by the perimeter wall that inhibits rearward core withdrawal inside the clubhead. In the exemplary embodiment of this pattern of reinforcing bars, the reinforcing bars are formed into hexagonal unit cells having a major diameter of 0.500 inches, although other geometric patterns are within the scope of the present invention.

This reinforced supporting wall is covered by a very hard plastic ball striking insert that is cast in situ(in place) over the supporting wall. That is, after the head is investment cast, the forward wall is cleaned and vulcanized with a bonding agent and placed in a mold that carries the configuration of the outer surface of the insert and an elastomeric material is either poured or injected under pressure into the mold to form the insert. One material that has been found successful is a Shore D 75 hardness polyurethane, which results in a very hard high frequency ball striking surface. This plastic insert, not only provides a very hard ball striking surface, but more importantly because it is intimately bonded to the forward wall and the reinforcing bars, it provides an effective "I" beam support with the bars for the forward wall as opposed to a "T" beam support found in today's rearwardly reinforced ball striking wall. It can be easily demonstrated by engineering calculation that I beam supports for transverse loads are substantially stronger than T beam supports.

The increase in the radius of gyration is accomplished by extending the heel and toe portions of the beyond present day parameters for high impact clubheads. These extensions provide greater effective heel and toe weighting. The heel of the clubhead is formed by extending the club face significantly beyond the hosel, that is, on the side of the hosel opposite the ball striking area, and extending the top wall and rear wall to accommodate this extended face. These extensions of the heel and toe are accomplished without any significant increase in overall clubhead weights, by extending the clubhead top wall downwardly almost to the plane of the sole plate, and flattening the rear wall almost to the plane of the sole plate. This design reduces perimeter wall and sole plate wall weight for a given size head and enables the saved weight to be positioned at the extended heel and toe portions of the clubhead.

Another advantage in the downward extension of the top wall and the flattening of the back wall almost to the plane of the sole plate is that at speeds normally encountered in ball driving; i.e., 100 to 150 feet per second, the resulting aerodynamic shape of the head eliminates the negative drag caused by present day clubhead designs as the clubhead passes through the hitting area. This is accomplished by firstly providing the top wall with a known airfoil shape in the vertical plane passing through the clubhead along the target line. Next, the clubhead back wall is flattened almost to the plane of the sole plate, and this results in the arc length of the top wall being somewhat greater than the arc length of the sum of the sole plate and back wall, all taken in that same vertical plane passing through the clubhead along the target line. Following known airfoil technology and the law of continuity of matter, this configuration results in the elimination of prior clubhead drag going through the ball striking area and in fact produces a slight upward force on the clubhead as it passes through the hitting area, and this effects ball overspin which is desirable in a driving club to produce increased total ball distance travel. Ball overspin of course causes the ball to roll further after it initially impacts with the ground.

Problems solved by technology

The forging technology was expensive because of the repetition of forging impacts and the necessity for progressive tooling that rendered the forging process considerably more expensive than the investment casting process and that distinction is true today although there have been recent techniques in forging technology to increase the severity of surface contours able them at considerable expense.

Faced with this dilemma of manufacturing a clubhead of adequate strength while limiting the weight of the clubhead in a driving metal wood in the range of 195 to 210 grams, designers have found it difficult to increase the perimeter weighting effect of the clubhead.

Such a face depth was not formerly believed possible because of the requirement for face structural integrity under the high impact loads at 100 to 150 feet per second, and the weight requirements of the clubhead of 195 to 210 grams.

There are however limitations on the effectiveness of the reinforcing elements on the face wall of investment cast clubs and particularly metal woods.

However, the perimeter wall extending rearwardly from the forward wall inhibits the direct rearward removal of these core pieces from the forward wall during the casting operation.

These limitations detract from the effectiveness of the reinforcing elements and their capability of achieving a lighter front ball striking wall.

In an "I" beam configuration, the width of the cross piece away from the forward wall, can be selected as desired but is extremely difficult to mold because of the undercut on the rear web.

To this date, however, increased perimeter weighting has not been found easy because of the weight and impact strength requirements in metal woods.

Since it is not practical, except for the techniques discussed in the above Raymont and Allen patents, to add weight to the perimeter wall because or the weight limitations of metal woods and particularly the driving woods, one alternative is to increase the moment arm or radius of gyration.

Another problem arises from the aerodynamics of today's metal woods as well as those of the "wooden" type.

The top wall in many metal and wooden woods has an aerodynamic shape but due lo the configuration of the sole plate and the back wall, there is no possible air foil lift generated in the normal clubhead impact speed range of 100 to 150 feet per second.

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