JP2007236945A - Metal wood club with improved hitting face - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal wood club with an improved hitting face having a relatively large zone of high initial ball velocity. <P>SOLUTION: The hitting face 2 of a golf club head has improved flexural stiffness properties. The hitting face 2 is made from multiple materials. Each material has a different tensile modulus of elasticity, where the center zone 4 of the hitting face 2 has a much higher tensile modulus of elasticity than the surrounding portions of the hitting face 2. This creates a stiff center zone 4 and a more easily deflected concentric portion. In another embodiment, the materials have different yield strengths, where the center zone 4 of the hitting face 2 has a very high yield strength compared to the surrounding portions of the hitting face 2. The hitting face 2 may then plastically deform around its periphery, while the center zone 4 retains its original shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the golf club head disclosed in Patent Document 1 and Patent Document 2, and the contents of the disclosure should be referred to as appropriate.

  The present invention relates to an improved golf club head. More specifically, the present invention relates to a golf club head having an improved striking face in which a zone with a high initial ball velocity is relatively large.

  It is well known that golf club designs are complex. The specifications of each club component (i.e., club head, shaft, hosel, grip, etc.) are directly linked to the performance of the club. Therefore, by changing the design specifications, it can be finished to realize special performance characteristics.

  Club head design has long been studied. More important considerations in club head design include loft, lie, face angle, horizontal face bulge, vertical face roll, center of gravity, inertia, material selection, and total head weight. This basic set of criteria is generally the focus of golf club engineering, but several other design aspects must also be considered. The internal design of the club head, such as the hosel housing, the means for coupling with the shaft, the peripheral weight of the club head, and the filler in the hollow club head can be adapted to achieve specific features.

  The golf club head must also be strong enough to withstand repeated impacts that occur during a collision between the golf club and the golf ball. The load that occurs at this moment gives the golf ball a force with a peak exceeding 907 kg (2000 pounds). For this reason, the club face and body must be designed to resist permanent deformation and critical damage due to material crushing and yielding. The face of the titanium hollow metal wood driver has a uniform face thickness greater than 2.5 mm, thereby ensuring structural integrity of the club head.

  Players typically seek a combination of metal wood drive and golf ball that achieves maximum distance and landing position accuracy. The ball flight distance after hitting is governed by the magnitude and direction of the translational speed of the ball and the rotational speed of the ball, ie, the spin. Environmental conditions including atmospheric pressure, humidity, temperature and wind speed further affect ball flight. However, the environmental effects are beyond the control of golf equipment manufacturers. The exact landing of a golf ball is also determined by many factors. Some of these factors are due to club head designs such as center of gravity and club head flexibility.

  The United States Golf Association (USGA), the governing body of golf regulations in the United States, has specifications for the performance of golf balls. These performance specifications define the size and weight of a compatible golf ball. One USGA regulation limits the initial velocity of a golf ball after a given impact to 76.2 m (250 ft) / sec + -2% (or a maximum initial velocity of 77.7 m (255 ft) / sec). Yes. In order to increase the flight distance of the golf ball, the ball speed after impact and the coefficient of restitution of the impact between the ball and the club must be optimized while satisfying this rule.

  In general, if the influence of the environment is ignored, the flight distance of the golf ball depends on the total kinetic energy applied to the ball during the impact by the club head. In the event of a collision, kinetic energy is transmitted from the club and stored as elastic strain energy in the club head and as viscoelastic strain energy of the ball. After impact, the energy stored in the ball and club is converted back to kinetic energy in the form of translational and rotational speeds of the ball and club. Since the collision is not completely elastic, some of the energy is consumed for club head vibration and ball viscoelastic relaxation. Viscoelastic relaxation is a material property of parimer materials used in golf balls.

  Ball viscoelastic relaxation is a source of parasitic energy, which depends on the deformation rate. In order to minimize this effect, it is necessary to reduce the deformation rate. This can be realized by increasing the deformation at the time of a club face collision. Since the deformation of the metal will be purely elastic, the strain energy stored in the club face returns to the ball after the collision, resulting in an increased jumping speed of the ball after the collision.

Various methods can be employed to vary the allowable deformation of the club face. This includes uniform face thinning, thin face with rigid members as ribs, variable thickness, and others. These designs must have sufficient structural integrity to withstand repeated impacts without permanent club face deformation. In general, in a conventional club head, the ball initial velocity after the collision changes according to the collision position of the club face. Accordingly, it is desirable in the art that a zone that achieves a large, substantially uniform ball initial velocity, or “sweet zone”, provides a large club head.
US Pat. No. 6,605,007 JP 2004-358225 A

  According to the present invention, the golf club head has a striking face having a central zone made of a first material, the central zone having a first elastic tensile modulus. The second zone is concentric with the central zone and is manufactured from a second material having a second elastic tensile modulus. The first elastic tensile modulus is greater than the second elastic tensile modulus.

  Preferred features of the present invention are disclosed in the accompanying drawings, wherein like reference numerals represent like elements in the several views.

  US Pat. No. 6,605,007, which forms the basis of the present invention, is an improvement that also substantially increases the zone of a substantially uniform high initial velocity or high coefficient of restitution (COR. The disclosed golf club is disclosed. The contents of that patent are incorporated herein by reference.

COR or coefficient of restitution is a measure of collision efficiency. COR is the ratio of the speed at separation to the speed at approach. In this model, COR was therefore defined using the following equation:
(V _club-post -V _ball-post ) / (V _club-pre -V _ball-pre )
here,
V _club-post represents the speed of the club after the collision.
V _ball-post represents the speed of the ball after the collision.
V _club-post represents the speed of the club before the collision (zero value in USGA COR condition).
V _ball-pre represents the velocity of the ball before the collision.

  COR is generally dependent on the shape and material properties of the impacting object. In a completely elastic collision, the COR is 1 (1.0) and the energy loss is zero (0.0). In an inelastic or completely plastic collision, the COR is zero and the impacted object does not separate after the collision, maximizing energy loss. This means that a large COR value results in a larger ball speed and distance.

  FIG. 1 corresponds to FIG. 2 of the parent application '341, and as shown in this figure, club accuracy and a large zone of uniform high initial velocity are realized by the striking face 2. The striking face 2 comprises a central zone 4, an intermediate zone 6 surrounding it and an optional surrounding zone 8. Preferably, the area of the central zone 4 is about 15% to about 60%, more preferably about 20% to about 50% of the total area of the striking face 2.

  The central zone 4 is relatively stiff and the intermediate zone 6 is relatively soft. As a result, when the ball collides, the intermediate zone 6 of the face 2 is deformed to realize a high ball speed. On the other hand, the central zone is not substantially deformed and the ball flies toward the target. When the ball collides, due to the deformation of the intermediate zone 6, the central zone 4 moves into the club head 10 and is pushed out. The intermediate zone 6 may be located adjacent to the central zone 4 and the optional surrounding zone 8 may be located adjacent to the intermediate zone 6. As a result, the head produces a coefficient of restitution exceeding 0.81.

Such a coefficient of restitution is achieved by imparting a first bending stiffness to the central zone 4 and a second bending stiffness to the intermediate zone 6. The bending stiffness (FS) is obtained by multiplying the average elastic modulus (E) of each part by the cube of the average thickness (t) of each part, that is, FS = Et ³ (Equation 1)
Is defined as

  Reference is made to the above-mentioned US Pat. No. 6,605,007 for details on how to calculate the average elastic modulus and thickness. The US patent also describes how to determine the FS when the thickness varies or when the material is non-uniform.

  Since the bending stiffness varies depending on the material and thickness, the following technique can be employed to form a substantial difference in the bending stiffness of the central zone 4 and the intermediate zone 6. (1) Different materials are used for each part. (2) Each part has a different thickness. Or (3) The material and thickness of each part are varied. For example, in the preferred embodiment, the thickness of the central zone is greater than the thickness of the intermediate zone and the material is common.

  In the club head 10, in order to achieve the above-described bending rigidity relationship, a material having a predetermined elastic modulus is selected and the thickness of each zone is changed. In another embodiment, in order to achieve the above-described bending stiffness relationship, the material of each part is changed to have a different elastic modulus, and the thickness is changed accordingly. Thus, the thickness of each zone may be the same or different depending on the elastic modulus of the material of each zone. Further, in order to obtain a desired bending rigidity, a structural rib, a reinforcing plate, and a thickness auxiliary material (parameter) may be used. The preferred ratio of flexural rigidity of the central zone 4 and the intermediate zone 6 is described in detail in the above parent application and US Pat. No. 6,605,007, to which reference is made.

Further, as discussed in the aforementioned US Pat. No. 6,605,007, the striking face 2 may be manufactured using two or more different uniform materials. For example, the central zone 4 has a generally uniform thickness and is made of stainless steel having a Young's modulus of 30.0 × 10 ⁶ lbs / in ² . Adjacent intermediate zones 6 continuously taper from the flat periphery to the central zone 4. The thickness of the intermediate zone varies linearly. The intermediate zone 6 is made of a titanium alloy having a Young's modulus of 16.5 × 10 ⁶ lbs / in ² .

  Referring now to FIGS. 2-3, another embodiment of the parent application, the '341 patent application, is shown. In this embodiment, the central zone 4 of the striking face 2 is formed by a face insert 42. The face insert 42 is preferably welded to the club head 10 along the weld line 20. The face insert 42 includes a polygonal or elliptical main plate portion 34 and side walls or wings 70 that extend in the direction of the crown 14 and form part of the crown 14. With such a configuration, the upper portion 71 of the weld line 20 is moved to the crown 14. By removing the distortion caused by the weld line 20 from the striking face 2, it is possible to suppress the occurrence of damage along the upper weld line 71 when receiving repeated impacts from the golf ball.

  The face insert 42 is preferably made of the same material as the rest of the club head 10. For example, titanium, titanium alloy, steel, or any other material suitable for use in a club head. The face insert 42 is preferably the same thickness as the other parts of the club head 10, but the face insert 42 may be thickened or thinned in order to change the bending rigidity.

  The shape and dimensions of the face insert 42 are various. As described above, the face insert 42 is a modified oval U-cup or L-cup, but may have other shapes. For example, a rectangle, an ellipse, or a circle. The face insert 42 preferably protects the entire surface of the striking face. However, the face insert 42 may form a smaller portion of the striking face. Further, the wing 70 may extend to the sole 22 to form a part of the sole. This is shown in FIG. It is only necessary to change the shape of the face insert 42. In this case, the affected weld line is the lower weld line 73.

  The material properties of the face insert 42 are affected by the technique selected to manufacture the face insert 42. For example, after the sheet metal is cold-rolled or cold-worked to align the metal crystal grains, the face insert 42 is preferably manufactured from the sheet metal by stamping. Stamping such metal makes the striking face stronger than other methods. Further, the face insert 42 is arranged in the striking face 2 so that the flow pattern of the grains is aligned in the direction from the sole to the crown. Alternatively, the grain flow pattern of the face insert 42 may be aligned in the heel-to-toe direction, that is, the diagonal direction. Other known techniques can be used to manufacture the face insert 42. For example, forging or casting.

  Preferably, the face insert 42 is formed by milling or stamping and forming. In the manufacturing process, malleable metals available for the striking face, such as titanium, titanium alloys, carbon steel, stainless steel, beryllium copper, and other forgeable metals are heated and forged to the desired shape of the face cup. Examples of suitable metals include, but are not limited to, titanium 6-4 alloy, titanium 15-3-3-3 alloy, titanium 20-4-1 alloy, and Daido Steel, Tokyo, Japan. Available DAT55 and DAT55G are included.

  A preferred forging process is die or billet forging, in which a premeasured rod of forgeable metal is heated and placed between the die and the hammer. The die has the desired shape of the face insert 42. The heated metal is processed into a desired shape by hammering. When the face insert 42 is manufactured by forging, the face thickness can be about 0.060 inches (about 1.5 mm) around its periphery.

  4-8, another embodiment of the present invention is shown. This embodiment combines both the previously described embodiments, i.e., the feature of having a striking face insert 42 with a central zone insert 44 having a main plate 34 disposed thereon. As shown most clearly in FIGS. 7 and 8, the central zone insert 44 can be any shape known in the art, for example, a polygon, oval, as a whole in an irregular shape, as shown. It is a flat member. The main plate portion 34 functions as a support for joining the central zone insert 44 by, for example, welding.

  As is known in the art, a weld line or joint is a discontinuous region, and even when two members of the same material are joined, the structural properties of the member change in the vicinity of the joint. By moving the weld line to the crown or sole of the club head, the striking face thickness can be adjusted more accurately, and the overall striking face thickness can be made thinner. It is also possible to change the characteristics of the striking face using the joint. In accordance with this aspect of the invention, the striking face 42 preferably has optional extensions 70, 73 that form part of the crown 14 and / or the sole 22.

  Preferably, two different materials are selected to construct the striking face 42. The first material is used to form the central zone insert 44 and the second material is used to form the remaining portion of the striking face 42. In other words, the central zone 4 of this embodiment is manufactured in the first embodiment, similar to the previously described central zone, and the transition zone 7 of this embodiment is similar to the transition zone described above. Manufactured from a second material. In this embodiment, the intermediate zone 6 is formed in the shape of the face support 30 of the striking face 2. This is the same as the intermediate zone described above. In this embodiment, the intermediate zone 6 may be made from a first material, a second material or a completely different material. Further, a part of the intermediate zone 6 may be disposed on the hitting face 42. The thickness of the central zone insert 44 may be uniform or variable, and may be the same as or different from the thickness of the striking face insert 42.

  The first alloy is selected such that its elastic tensile modulus ε1 is significantly greater than that of the second alloy. Preferably, the ratio of ε1 to ε2 is as large as a practical material. An example of a suitable material is a titanium alloy. Preferably, the selected materials are weldable to each other.

The performance of the golf club head 10, particularly the hitting face 2 of the head designed as a driver, is generally equivalent to the physics of plate behavior. Typical characteristics expressed in equations for evaluating plate behavior in relation to deflections and stresses are the industry's industry to generate the following equations using standard hypotheses in basic plate theory: It takes the form of a known constant.
D = εt ³ / (12 (1-v ² )) (Formula 2)
Where ε is the elastic tensile modulus, t is the thickness of the plate, and v is the Poisson's ratio. In a preferred embodiment, when a titanium alloy is used, ε ranges from about 70 GPa to about 128 GPa and v ranges from about 0.33 to about 0.35. The thickness t of the plate of the invention depends in particular on the manufacturing technique and material properties, so that the club face withstands the repeated high impact forces associated with the golf ball during the lifetime of the club. It will be a thing.

The structural behavior of the striking face can be partially adjusted by selecting an alloy with a different elastic tensile modulus. As is known in the art, the solution of the deflection w of a circular plate loaded with a point load P in the center with a radius a is as follows.
w = Pa ² / (16πD) (Formula 3)

  Therefore, the deflection w is determined in part by the elastic tensile modulus ε of the circular plate material. Although the striking face 42 and the central zone insert 44 are not perfectly circular plates, the deflection of both the striking face 42 and the central zone insert 44 can be approximated by Equation 3. As is known in the art, the actual deflection w of a plate of specific material properties and thickness can be determined using various techniques including the finite element method.

  Alternatively, the first and second materials have various elongation and yield strengths. Preferably, the central zone insert 44 is manufactured from a first material having a very high yield strength. On the other hand, the main plate portion 34 and the extended portions 70 and 73 of the striking face 42 are manufactured from a second material having a significantly lower yield strength. For example purposes, the central zone insert 44 may be made of titanium, while the main plate portion 34 and the extension portions 70, 73 may be made of steel. By utilizing a material with a lower yield strength, this embodiment can realize the advantage of the plastic deformation behavior of a material with a lower yield strength. When the golf ball hits, the striking face 2 receives stress due to impact force. If a portion of the striking face 42 experiences a stress level that exceeds the yield strength, that portion will stretch. Since the yield strength of the central zone insert 44 is significantly greater than the yield strength of the surrounding portion of the striking face 42, the central zone insert 44 is subject to such plastic deformation, although the main plate portion 34 is slightly plastically deformed. Not receive. That is, the peripheral portion of the main plate portion 34 acts like a hinge with respect to the central zone insert 44 and the impact stress is redistributed to the harder region of the striking face 42.

  Although various aspects of the present invention have been described so far, it will be apparent that the various features of each embodiment can be used alone or in combination. Thus, it should be apparent that the present invention should not be limited to the specific preferred embodiments described herein. Further, it is obvious that those who have knowledge in the field to which the present invention can make modifications and changes within the spirit and scope of the present invention. For example, the thickness may change stepwise or continuously in the face or individual zones. In other variations, surrounding zones that are thicker or thinner than adjacent intermediate zones may be used. Furthermore, the shapes of the central, intermediate and surrounding zones are not limited to the shapes described above. Accordingly, all modifications that can be readily made by a person skilled in the art in accordance with the disclosure contained herein without departing from the spirit and scope of the present invention are described in the other embodiments of the present invention. Included as The scope of the invention is defined by the claims.

1 is an exploded front view of a golf club head according to the present invention as shown in the parent application. FIG. 1 is a perspective view of a golf club head according to the present invention as shown in the parent application. FIG. FIG. 3 is a reverse perspective view of the golf club head of FIG. 2. 6 is a perspective view of an alternative embodiment of a golf club head according to the present invention. FIG. FIG. 5 is a plan view of the golf club head of FIG. 4. FIG. 5 is an exploded perspective view of the golf club head of FIG. 4. FIG. 5 is a perspective view of a hitting face of the golf club head of FIG. 4. FIG. 8 is an exploded view of the striking face of FIG. 7.

Explanation of symbols

2 hitting face 4 central zone 6 intermediate zone 7 transition zone 8 peripheral zone 10 golf club head 14 crown 20 weld line 22 sole 30 face support 34 main plate portion 42 hitting face insert 44 central zone inserts 70, 73 extension

Claims (10)

Having a striking face,
This striking face
A central zone having a first material and having a first elastic tensile modulus;
A second zone concentric with the central zone, the second zone having a second material with a second elastic tensile modulus, wherein the first elastic tensile modulus is the second A golf club head characterized by being larger than an elastic tensile modulus.   The golf club head according to claim 1, wherein the yield strength of the first material is smaller than the yield strength of the first material.   The golf club head according to claim 9, wherein the second material is deformed upon collision to redistribute the collision stress to the first material.   The golf club head of claim 1, wherein the ratio of the first elastic tensile modulus to the second elastic tensile modulus is maximized.   The golf club head according to claim 1, wherein the hitting face is welded to the club head. The golf club head of claim 1, wherein the central zone is welded to the second zone.   The golf club head according to claim 1, wherein the hitting face further has a crown extension.   The golf club head according to claim 1, wherein the hitting face further has a sole extension.   The golf club head of claim 1, wherein the first and second materials comprise an alloy of the same material.   8. A golf club head according to claim 7, wherein the same material is titanium.

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