JP2004358224A - Golf club head with variable flexural stiffness for controlled ball flight and trajectory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf club head which includes a hitting face comprising a plurality of discontinuous zones each having different flexural stiffness, improves accuracy and increases a repulsive coefficient. <P>SOLUTION: The hitting face comprises a directional control portion, which has at least two zones with different flexural stiffnesses. When the hitting face strikes a golf ball, the two zones deform differently to selectively control the direction of the flight of the golf ball. The directional control portion may comprise an upper zone and a lower zone, where the upper zone has a lower flexural stiffness or the lower zone has a lower flexural stiffness. Alternatively, the directional control portion may comprise a left zone and a right zone, and either the left or right zone may have a lower flexural stiffness to selectively control the lateral launch angle either to the left or right. The hitting face may further comprise a central zone disposed within the directional control zone, wherein the central zone has a flexural stiffness of at least about three times the flexural stiffness of the directional control zone. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  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 that includes a plurality of discontinuous zones having different bending stiffnesses to improve accuracy and increase coefficient of restitution.

  It is well known that golf club designs are complex. The use of club components (i.e., club head, shaft, hosel, grip, and those components) is directly linked to club performance. 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, face progression, face size, sole curvature, center of gravity, 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 of coupling with the shaft, the club head face or body peripheral weight, and the filler in the hollow club head can be adapted to improve acoustics.

  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 causes the golf ball to exert a force on the golf ball that is several times the order of gravity. 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 thickness of a hollow metal wood driver made of titanium is typically uniform and greater than 0.010 inches, thereby ensuring the 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 rotation speed of the ball, that is, 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 the 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 rule limits the initial velocity of a golf ball after a given impact to 250 feet / second + -2% (or a maximum initial velocity of 255 feet / second). 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. Generally, in a conventional club head, the coefficient of restitution (COR) changes according to the collision position of the club face. Furthermore, the accuracy of conventional clubs is highly dependent on the impact location.

  Accordingly, there is a need for a golf club having a striking face that maximizes the flight distance of the golf ball while maintaining the landing accuracy of the golf ball.

  The present invention relates to a golf club head adapted to a shaft attachment. The head has a face and a body. The face has a shape and dimensions that include a central portion and an adjacent enclosing intermediate portion. The middle part is relatively stiff and the middle part is relatively flexible, and the middle part of the face is deformed to increase the ball speed when the ball collides, while the middle part is not substantially deformed. So that the ball flies towards the target. Therefore, at the time of the ball collision, the intermediate portion is deformed, and the central region moves in and out of the club head as a unit. As a result, the head achieves a coefficient of restitution greater than 0.81.

The above points can be realized by giving a first flexural rigidity to the central portion and giving a second flexural rigidity to the intermediate portion. The bending stiffness is defined as the Young's modulus, that is, the elastic modulus (E) multiplied by the cube of the thickness of the part, that is, Et ³ . The first bending stiffness is significantly different from the first bending stiffness. As a result, at the time of the ball collision, the intermediate portion is substantially deformed and the central portion is moved into the head, and the deformation of the central portion is minimized.

  In one embodiment, the first bending stiffness is at least three times the second bending stiffness. In other embodiments, the first bending stiffness is between 6 and 12 times the second bending stiffness. More preferably, the first bending stiffness is greater than 25,000 lb · in. Most preferably, the first bending stiffness is as high as 55,000 lb · in. Preferably, the second bending stiffness is less than 16,000 lb · in. More preferably, the second bending stiffness is less than 10,000 lb · in.

  Since the bending rigidity depends on the characteristics and thickness of the material, the following method can be employed to realize a substantial difference in rigidity between the first bending rigidity and the second. (1) Use different materials for each part. (2) Use different thickness for each part. (3) Use different materials and different thicknesses for each part. For example, in one embodiment, the thickness of the central portion is greater than the thickness of the middle portion, and the material of both portions is the same, for example, titanium or steel.

  The golf club head may further include a peripheral view between the intermediate zone and the body of the club. In one embodiment, the bending stiffness of the peripheral zone is a third bending stiffness that is at least twice as large as the second bending stiffness. The area of the periphery is preferably less than 30% of the total area of the golf club head face.

  In an alternative embodiment, the golf club head includes a shell and a face that define an internal cavity. The face defines a face region and has a central first portion and a second portion adjacent thereto. The first portion has a first thickness and defines a first area. The second portion has a second thickness. The first area is between about 15% and about 60% of the total area of the face, and the first thickness is greater than the second thickness. More preferably, the first area is between about 20% and about 50% of the face area. The shell further has a top crown portion and a separated sole plate, a heel portion and a separated toe portion, and a back surface separated from the face.

  In the club head described above, the first, second and third portions can take various shapes, such as b, a face shape or an elliptical shape. Furthermore, the internal cavity of the club head can have a volume of about 250 cubic centimeters, more preferably about 275 cubic centimeters. The club head face preferably has a loft of less than about 13 °.

  Further, the central, intermediate and peripheral portions can each have various thicknesses.

  Another feature of the present invention is that the center of gravity of the club head is arranged in relation to an orthogonal coordinate system. The origin of the Cartesian coordinate system coincides with the geometric center of the striking face. The X coordinate is a horizontal axis at a position in contact with the geometric center of the hitting face, and the heel direction of the club is the positive direction. The Y axis is another horizontal axis orthogonal to the X axis, and the positive direction is the back direction of the club. The Z axis is a vertical axis orthogonal to the X axis and the Y axis, and the positive direction is the crown direction of the club. The center of gravity is preferably at a lower position behind the geometric center of the face.

  In one embodiment, the center of gravity is separated from the geometric center along the Z axis by a first distance of at least about 0.1 inch. More preferably, the center of gravity is spaced from the geometric center along the Z-axis toward the sole plate and the first distance is at least about 0.15 inches. In other embodiments, the center of gravity is separated from the geometric center by a second distance along the X axis, the second distance being less than about 0.02 inches. Further, the center of gravity is separated from the geometric center along the Y axis by a third distance toward the back portion, the third distance being less than about 1.25 inches.

  The present invention is also directed to a golf club equipped with a striking face and adapted for shaft attachment. The face has a total face area and a first main resonance frequency, which is preferably less than about 2900 Hz. The face further has a central zone including the geometric center of the face and an intermediate zone disposed adjacent to the central zone. The central zone has a first bending stiffness and a central zone area, which is at least 15% of the total face area. The intermediate zone has a second bending stiffness. The first bending stiffness is at least 25,000 lb · in and is greater than the second bending stiffness.

  One embodiment of the present invention is adapted to attach to a shaft and has a striking face, the striking face has a direction control portion, and the direction control portion has two or more zones of different bending stiffness. It is directed to a golf club that selectively deforms the flight direction of the golf ball by deforming the zone to a different extent when the hitting face collides with the golf ball. The striking face further has a central portion in the directional control portion that includes the geometric center of the striking face, wherein the bending stiffness of the central portion is at least about three times, preferably at least about, the bending stiffness of the directional control portion. 6 times, more preferably at least about 12 times greater.

  The golf club head may further include a peripheral portion around the direction control portion, wherein the bending stiffness of the peripheral portion is at least about twice that of the direction control portion. According to one aspect, the bending stiffness of the first zone of the two or more directional control zones is between about 8,500 lb · in and about 60,000 lb · in. The bending stiffness of the second zone of the two or more directional control zones is about 0.5 to about 2 times the bending stiffness of the first zone. Further, the bending rigidity of the third zone of the two or more direction control zones is about 0.7 to about 1.3 times the bending rigidity of the first zone, and the bending rigidity of the fourth zone of the two or more direction control zones is The bending stiffness is about 0.7 to about 2 times that of the first zone.

  The directional control portion may have an upper crown zone and a lower heel zone, and may have a side heel zone and a side toe zone. Alternatively, the direction control portion may comprise all four of these zones. Preferably, these four zones are delineated by the vertical centerline and horizontal centerline of the striking face.

  1-5, a first embodiment of a golf club head 10 of the present invention is shown. The club head 10 includes a shell 12 having a body 14, a striking face 16, a toe portion 18, a heel portion 20, a sole plate 22, a hosel 24, a bottom portion 26, a crown portion 28, and a back portion 29. Sole plate 22 fits into recess 30 (shown in FIG. 5) in bottom portion 26 of body 14. Shell 12 and sole plate 22 create an internal cavity 31 (shown in FIG. 5). The striking surface 16 may include an outer surface 32 and an inner surface 34, and the outer surface 32 may additionally include a groove 35.

  A golf ball shaft (not shown) is attached to the hosel 24 and is disposed along the shaft axis SHA. The hosel may extend to the bottom of the club head, may stop between the top and bottom of the head, or the hosel may terminate flatly at the top portion and extend into the head cavity.

  The inner cavity 31 of the club head 10 may be a cavity or may be filled with a foaming agent or other low specific gravity material. It is desired that the volume of the internal cavity 31 be greater than 250 cubic centimeters, more preferably greater than 275 cubic centimeters. Preferably, the mass of the club head of this invention is greater than 150 grams but less than 220 grams.

  With reference to FIGS. 3-3B, the face 16 includes a central zone or portion 36, an intermediate sone or surrounding portion 38 adjacent to the central zone 36, and an additional peripheral zone or outer portion 40. The intermediate zone 38 preferably surrounds the central zone 36 and the peripheral zone 40 preferably surrounds the intermediate zone 38. The peripheral zone 40 is disposed between the intermediate zone 38 and the crown portion 28. In the following description and claims, the central zone 36 is a continuous zone disposed in the center of the striking face 16 and includes the geometric center (“GC”) of the striking face.

Zones 36, 38, and 40 are similar in shape to the striking face 16 except that their area is small as will be described below. Preferably, the thorns 36, 38 and 40 are substantially concentric with each other within the striking face 16. Central zone 36 has a first thickness _{t 1.} The intermediate zone 38 has a second thickness _{t 2.} First thickness _{t 1} is greater than the thickness _{t 2} of the second. Typically, the peripheral zone 40 becomes thicker than the intermediate zone 38 when casting the club head. However, the present invention is not limited to such calibration. Preferably, the first thickness t ₁ is equal to about 1.5 times to about 4 times the second thickness t ₂ of the intermediate zone 38.

The thickness relationship between zones 36, 38 and 40 is determined such that a predetermined relationship is achieved between the bending stiffness achieved by each zone. The bending stiffness (FS) of each zone is defined by the following simplified formula.
FS = E × t ³
Where E = elastic modulus of the material of the zone, that is, Young's modulus t = zone thickness

Central zone 36 has a first bending stiffness FS _1. The intermediate zone 38 has a second flexural rigidity FS _2. Peripheral zone 40 has a third flexural rigidity FS _3. The predetermined relationship between the zones is that the first bending stiffness FS ₁ is substantially greater than the second bending stiffness FS ₂ and, optionally, the third bending stiffness FS ₃ is the second bending stiffness. is that substantially larger than FS _2. Preferably, three times greater than the first bending stiffness FS ₁ at least a second flexural rigidity FS _2. As a ratio, the following relationship needs to be satisfied.
_{(FS 1 / FS 2)>} = 3
The expression ratio rigidity FS ₂ Flexural bending intermediate zone of stiffness FS ₁ of the central zone means that at least 3.0. If the above bending stiffness ratio is less than 3, the central zone is subjected to excessive deformation at the time of collision, and the accuracy of the club decreases. More preferably, the first bending stiffness FS ₁ is at least 6 to 12 times greater than the second bending stiffness FS ₂ , and most preferably the first bending stiffness FS ₁ is at least the second bending stiffness FS ₂ . Greater than about 8 times.

Preferably, the third bending stiffness FS ₃ is at least twice as large as the second bending stiffness FS ₂ . Therefore, the following relationship needs to be satisfied.
(FS ₃ / FS ₂ )> = 2
In the club head 10 (as shown in FIG. 3), the above-described flexural rigidity relationship is achieved by selecting a predetermined material having a specific elastic modulus and changing the zone thickness. In other embodiments, the bending stiffness relationship can be achieved by changing the zone materials to each other so that the zones have different moduli of elasticity, and correspondingly changing the pressure. Therefore, the thickness of each part can be the same or different depending on the elastic modulus of the material of each part. It is also possible to obtain a desired bending stiffness ratio through structural ribs, reinforcing plates and thickness parameters.

Quantitatively, the first bending stiffness FS ₁ is preferably greater than 20,000 lb · in. If the first bending rigidity FS ₁ is smaller than 20,000 lb · in, the central region is excessively deformed at the time of collision, and the accuracy is reduced. More preferably, the first bending stiffness FS ₁ is greater than 55,000 lb · in. Preferably, the second flexural rigidity FS ₂ is less than 16,000lb · in. If the second bending stiffness FS ₂ is greater than 16,000 lb · in, the COR and the resulting ball speed will decrease. More preferably, the second bending stiffness FS ₂ is less than 10,000 lb · in, and most preferably less than 7,000 lb · in.

  Referring to FIG. 3, the central portion 36 preferably has a first area between about 15% and about 60% of the outer surface region 32 or face region. The percentage of the face area is calculated by dividing the area of each zone 36, 38 or 40 by the total face area of the outer surface 32. Note that the total face area of outer surface 32 is equivalent to the sum of the areas of zones 36, 38 and 40. In the preferred embodiment, the central zone first area is greater than about 15% and less than about 60% of the total face area. If the central zone 36 is less than 15% of the total face area, the accuracy is reduced. When the central zone 36 is greater than 60% of the face area 32, the COR decreases.

  Referring again to FIG. 1, the club head 10 is positioned so that the center of gravity of the club head 10 is in a predetermined relationship with an orthogonal coordinate system whose origin is located on the outer surface and coincides with the geometric center GC of the face 16. It is manufactured. The face includes a vertical center line VCL and a horizontal center line HCL perpendicular thereto. The geometric face center GC is the intersection of these center lines VCL and HCL. Preferably, the geometric center of the central zone 36 coincides with the geometric sleeping GC of the club face.

  The Cartesian coordinate system is defined when the club head is placed on a flat surface (ie, with a natural loft) and has three axes, as shown in FIG. The origin of the Cartesian coordinate system preferably coincides with the geometric center of the striking face. The X coordinate is a horizontal axis at a position in contact with the geometric center of the hitting face, and the heel direction of the club is the positive direction. The Y axis is another horizontal axis orthogonal to the X axis, and the positive direction is the back direction of the club. The Z axis is a vertical axis orthogonal to the X axis and the Y axis, and the positive direction is the crown direction of the club. The center of gravity is preferably at a lower position behind the geometric center of the face.

Referring to FIG. 1, the position of the center of gravity is defined by the coordinates CG _z , CG _x , and CG _y of the center of gravity in relation to the Z, X, and Y axes, respectively. In the vertical direction along the Z axis, the ten-piece coordinate is represented by CG _z , and is separated from the geometric face center G by the first distance D1 along the Z axis. The first distance D1 is at least about −0.1 inches, and more preferably the first distance D1 is at least about −0.15 inches so that the vertical center of gravity is below the geometric center GC. ing.

In the horizontal direction along the X-axis, the barycentric coordinate is represented by CG _x and is separated from the geometric face center GC by the second distance D2. The second distance D2 is less than about 0.02 inches and greater than about −0.02 inches, so that the horizontal center of gravity is no more than the distance D2 from the center GC.
In one embodiment, the center of gravity is separated by a first distance of at least about 0.1 inch from the geometric center along the Z axis. More preferably, the center of gravity is spaced from the geometric center along the Z-axis toward the sole plate and the first distance is at least about 0.15 inches. In other embodiments, the center of gravity is separated from the geometric center by a second distance along the X axis, the second distance being less than about 0.02 inches. Further, the center of gravity is separated from the geometric center along the Y axis by a third distance toward the back portion, the third distance being less than about 1.25 inches.

Referring to FIG. 1, along the Y-axis, the barycentric coordinates are expressed as CG _{y and} are loaded from the geometric face center GC, preferably on the back portion 29, by a third distance D3. The center of gravity CG _{y in} the third direction is preferably no greater than about 1.25 inches, and more preferably is about 1 inch.

[Experimental example]

These and other aspects of the invention will be more fully understood with reference to the following non-limiting examples. These are merely examples of golf club embodiments of the present invention and are not to be understood as limiting the present invention. The scope of the invention is defined by the appended claims.

The comparative example 1-3 is comprised by the dimension as above using the material whose zone has a predetermined value. As a result, for the comparative example, the ratio of the central zone bending stiffness to the adjacent intermediate zone bending stiffness is 1.0, 2.2 and 0.9. These ratios deviate from the preferred ratio according to one aspect of the invention, ie (FS ₁ / FS ₃ > = 3). On the other hand, the example of the present invention has dimensions and shapes such that (FS ₁ / FS ₃ = about 8). In the above example, the intermediate zone is defined by a first intermediate zone adjacent to the central thorn and a second communication zone adjacent to the first intermediate zone. The peripheral zone is adjacent to the intermediate zone.

Comparative Examples 1 and 3 have FS ₃ / FS ₂ ratios of 1.0 and 1.8, respectively. These ratios also deviate from the preferred ratio according to another aspect of the invention, ie (FS ₃ / FS ₂ > = 2). Comparative Example 2 and the example of this invention are 3.4 and 4.1, respectively, satisfying such a ratio.

  The center of gravity of the club head of the example of the present invention was realized by adding 31.5 grams of weight to the sole plate in addition to the shape and dimensions of the club head. Employing other known weight operations can realize the center of gravity position.

As a result, referring to FIG. 1, in the example club head of the present invention, the center of gravity is located at least 0.10 inches below the geometric face center GC along the Z axis and the geometric face along the X axis. It is within 0.01 inches from the center GC and within 1.25 inches from the geometric face center GC along the y-axis. The parameter column in Table 2 indicates the distance at which the centroid is away from the face geometric center GC along each coordinate axis in relation to the Cartesian coordinate system for each position or coordinate of the centroid. The center of gravity of Comparative Example 1-3 is arranged along the Z axis and X axis without appropriately reflecting the conditions of the present invention. The center of gravity of the example of the present invention is arranged appropriately reflecting the strip of the present invention in the Z, X and Y axes.

  The numerical test results in Table 3 were generated using computer technology including a finite element analysis model. When the computer models the example club, the following assumptions were made: That is, the club head loft was 8.5 °; the club head mass was 201 grams; and the club head material was 6AL-4V titanium alloy. The golf ball used was a two-piece solid ball. Finite element return was used to predict ball launch conditions, and trajectory model was used to predict distance and landing area. The conditions for the swing used to predict or test the total distance and landing area are: club head speed is 109.1 mps, attack angle is +2 degrees, and the face vertical plane is at an angle of 8.5 degrees to the speed vector. The impact conditions used for the club coefficient of restitution (COR) test in which the clubs are oriented to comply with the USGA Golf Rules, and more particularly, according to Rule 4-1e, Appendix II, 2nd Edition, February 8, 1999. .

COR, or coefficient of restitution, is one technique for measuring the repulsive force of a ball. 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 _ball-pre -V _club-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 generally depends on the shape and characteristics of the impacting object. In a completely elastic collision, the COR is 1 and the energy loss is zero. 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. Thinner face club heads also achieved higher COR values, which can be seen by comparing Comparative Example 3 with Comparative Example 1. However, unexpectedly, the inventive examples have a larger COR. In the club head of this invention, the preferred COR is greater than about 0.81, more preferably greater than 0.83.

  As the COR increases, the flight distance of the ball increases and the maximum total distance is expected to increase. The example of the invention achieves the largest maximum total distance with the largest COR.

  It is also expected that shot accuracy will decrease as COR increases. However, the example of the present invention has the highest COR and the best accuracy as the landing area data shows. The landing area is an area that wraps around the positions of nine balls by colliding with various positions of the club. The nine impact locations were equally spaced in a 1 inch wide, 0.5 inch high rectangular area concentric with the geometric center of the club face. The club head of the example of this invention has the smallest landing area of 341 square yards. Comparative Example 3 is the only comparative example with a sufficient COR of at least 0.81, but the landing area is 1000 square yards, which is significantly larger than the landing area of the club of the present invention. The smaller the landing area, the greater the club accuracy.

  Several alternative embodiments of the invention are also feasible. Features of the invention include the bending stiffness of the individual zones of the club head and the ratio of bending stiffness between parts. A wide variety of rib structures and alternative materials can be used to meet the essential requirements of the flexural rigidity and flexural rigidity ratio of the face portion.

In FIG. 3-3B, a preferred embodiment of the club head 10 is shown. The club 10 has a face 16 having the following structure. The central zone 36 has a thickness t ₁ of about 0.150 inches, the intermediate zone 38 has a thickness t ₂ of about 0.075 inches, and the peripheral zone 40 has a thickness t ₃ of about 0.120 inches. Have Further, the central zone 36 includes about 20% of the total face surface area and the peripheral zone 40 includes less than about 20% of the total face surface area. Each of the three zones 36, 38 and 40 has a uniform thickness within the zone and is a single uniform material, preferably having a Young's modulus (E) of about 16.5 × 10 ⁶ lbs / in ² . It is composed of a titanium alloy.

ここで、
Ａｉはゾーン内の要素の面積であり、
Ｅｉはゾーン内の要素のポンド・パー・平方インチで表したヤング率であり、

はゾーンのトータル面積を表し、
ｔｉはインチで表したゾーンの要素の平均厚さであり、
ｎはゾーン内の要素の数である。
この一般式は、各ゾーンが均一の厚さを有し、定数のヤング率を有すると、上述した、簡略式、ＦＳ_ｚ＝Ｅｔ^３に変形できる。 Referring to FIG. 3-3B, may be defined by the general formula of flexural rigidity FS ₂ Hatsugi.

here,
Ai is the area of the element in the zone,
Ei is the Young's modulus in pounds per square inch of the elements in the zone,

Represents the total area of the zone,
ti is the average thickness of the zone elements in inches,
n is the number of elements in the zone.
This general formula can be transformed into the simplified formula, FS _z = Et ³ described above, when each zone has a uniform thickness and a constant Young's modulus.

Using a simplified formula, the bending stiffness can be calculated for the center and adjacent zones, and the bending stiffness ratio can be calculated. The bending stiffness ratio of the golf club head 10 of the preferred embodiment is calculated as follows.
^{_{FS c = E c t c 3}} = (16.5 × 10 6 lb / in 2) (0.15in) 3
= 55,689 lb · in
FS _I = E _I t _I ³ = (16.5 × 10 ⁶ lb / in ² ) (0.075 in) ³
= 6,961 lb · in
Here, FS _c is the bending stiffness of the central region 36 (also indicated by FS ₁ ), and FS _I is the bending stiffness of the intermediate region 38 (also indicated by FS ₂ ). These values are also reported in Table 1 above. Therefore, the bending rigidity ratio of the golf club head 10 is (FS _c / FS _I ) = 8.0.
It is.

  In FIG. 6, an alternative embodiment of the club head 110 is shown and an alternative structure of the striking face 116 is described that provides a flexural rigidity ratio to the adjacent intermediate zone of the central portion similar to the embodiment of FIG. In this club head 110, the face 116 has an elliptical central zone 136 and an adjacent intermediate zone 138. The central zone 136 occupies about 30% of the total face surface area.

7-7B, the central zone 136 has a rib support structure 137a (shown in dashed lines) that extends from the internal surface of the face. An asterisk-shaped rib structure has a plurality of ribs or legs to enhance the rigidity of the central zone. The thickness t _1A of the central zone rib portion 137a is about 0.225 inches. The rib width w is about 0.085 inches. The thickness t _1B of the remaining portion 138b between the ribs of the central zone is about 0.075 inch. The rib structure 137a is defined to include approximately 25% of the surface area of the central zone. The intermediate zone 138 has a uniform thickness t ₂ of about 0.075 inches and extends to the boundary of the face 116 and no peripheral zone is defined. The face 116 is preferably made of a uniform titanium alloy having a Young's modulus (E) of about 16.5 × 10 ⁶ lbs / in ² .

  Referring to FIGS. 6-7B, the bending stiffness ratio between the central region 136 and the adjacent intermediate zone 138 is calculated and is as follows.

The area of the ellipse central region 136 is A _C = π × b × a, “b” is ½ of the major axis of the ellipse, and “a” is ½ of the minor axis of the ellipse. When the major axis is 2 inches and the minor axis is 1 inch, the area of the central region is 1.57 in ² .

The area of the rib is simply the width (WI = 0.085 inch) times its length (LI = 4.6 inch), ie WI × LI = 0.39 in ² .

Therefore, the non-rib area A _NR = A _c −A _r = (1.57−0.39) = 1.18 in ² .

Therefore, the general formula of the bending stiffness described above is converted as follows.
FS _c = (A _r / A _c ) Et _1A ³ + (A _R / A _C ) Et _1B ³
FS _c = (0.39 / 1.57) (16.5 × 10 ⁶ lb / in ² ) (0.225 in) ³ + (1.81 / 1.57) (16.5 × 10 ⁶ lb / in ² ) (0.090in) ³
FS _c = 56,008 lb · in
FS _I = E (t ₂ ) ³ = (16.5 × 10 ⁶ lb / in ² ) (0.075 in) ³
= 6,961 lb · in
Therefore,
(FS _c / FS _I ) = 8.05
It is.

  Ribs, welts, pimples or other discontinuous thickness changes in a zone can be treated as discontinuous elements in a specific zone and calculated according to the general formula described above governing bending stiffness.

  6, an alternative embodiment of the club head 210 is shown and an alternative structure of the striking face 216 is described that provides a flexural rigidity ratio to the adjacent intermediate zone of the central portion similar to the embodiment of FIG. In this club head 210, the face 216 has an elliptical central zone 236 and an adjacent intermediate zone 238. The central zone 236 occupies about 30% of the total face surface area. Club head 210 does not define a peripheral zone.

Referring to FIGS. 9-9B, the central zone 236 has a uniform thickness t ₁ of about 0.140 inches. The intermediate zone 238 has a continuously tapered thickness from the face periphery to the central zone 236. The thickness of the intermediate zone 238 is defined as continuously changing.

The intermediate zone 238 has an inner thickness t _2A of about 0.07 inches at the boundary between the central zone 236 and the intermediate zone 238. Intermediate zone 238 has an outer internal thickness t _2B of about 0.10 inches. The outer thickness is that around the face. In an example where the thickness is not uniform within a zone, primarily in relation to a continuous taper zone, the average thickness is used to calculate the bending stiffness of that zone. This approximation simplifies the calculation and is physically based on the elastic shell theory.

In this embodiment, two uniform materials are used. The central zone 236 is preferably made from stainless steel with a Young's modulus of 30.0 × 10 ⁶ lb / in ² and the adjacent intermediate zone 238 is made from a titanium alloy with a Young's modulus of 16.5 × 10 ⁶ lb / in ^2. .

With reference to FIGS. 8-9A, the bending stiffness of the central and adjacent zones is calculated.
FS ^_c = _{E c t c} ³
= (30 × 10 ⁶ lb / in ² ) (0.140 in) ³
= 82,320lb · in
FS _I = E _I (t _2A + t _2B / 2) ³
= (16.5 × 10 ⁶ lb / in ² ) ((o.1 + 0.07) in / 2) ³
= 10, 133 lb · in
Therefore,
(FS _c / FS _I ) = 8.12
It is.

  In FIG. 10, an alternative embodiment of the club head 310 is shown and an alternative structure of the striking face 316 is described that provides a flexural rigidity ratio to the adjacent intermediate zone of the central portion similar to the embodiment of FIG. In the club head 310, the face 316 has an elliptical central zone 336 and an adjacent intermediate zone 338. The central zone 336 is manufactured using two materials 337a (shown with dashed lines) and 337b (shown with dashed lines).

The central zone 336 has a uniform thickness t ₁ of about 0.140 inches. The first material 337a is a titanium alloy having a Young's modulus of 16.5 × 10 ⁶ lb / in ² . The second material 337b is stainless steel with a Young's modulus of 30 × 10 ⁶ lb / in ² . The central zone 336 contains about 60% stainless steel.

Further, the central zone 336 is elliptical and has a total face surface area of about 25%. The intermediate zone 338 is accompanied by a peripheral zone 340 and includes 20% or less of the total face surface area. The intermediate zone has a thickness t ₂ of about 0.08 inches and is constructed from the same titanium alloy as the central zone 336.

  Referring to FIGS. 10-11AB, the bending stiffness ratio between the central region 336 and the adjacent intermediate zone 338 is calculated and is as follows.

Using the above equation for determining the area of the ellipse, assuming that the major axis is about 1.8 inches and the minor axis is about 0.9 inches, the area of the central region 336 is A _C = 1.272 in ² . As described above, the area (A _S ) of stainless steel is 60%, and the area of titanium or non-steel (A _NS ) is 40%.
_{FS c = (A S / A} C) E S (t 1) 3 + (A NS / A C) E t (t 1) 3
FS _c = (0.60) (30 × 10 ⁶ lb / in ² ) (0.14 in) ³ + (0.40) (16.5 × 10 ⁶ lb / in ² ) (0.14 in) ³
FS _c = 67,502 lb · in
FS _I = E _t (t ₂ ) ³ = (16.5 × 10 ⁶ lb / in ² ) (0.080 in) ³
= 8,448 lb.in
Therefore,
(FS _c / FS _I ) = 8.0
It is.

  Considered in FIGS. 1-11A, golf club head examples 10, 110, 210 and 310 show four unique face structures that provide similar flexural stiffness, where the ratio of the central zone to the adjacent zone Is greater than or equal to 3, more preferably greater than about 8. If the face structure is uncertain due to manufacturing errors or methods, or other possible reasons, a non-destructive test method may be applied to a given face structure to determine non-bending stiffness.

  Referring to FIG. 12, a typical club 410 is shown and the face thickness profile is unknown. Preferably, certain matters relating to the structural material of the face are known or have been determined experimentally by test methods known to those skilled in the art. In FIG. 12, random distribution points on the face 416 are shown. This distribution is referred to herein as a “point cloud” or a predetermined point distribution. The point labeled C indicates the position within the central zone 436. The point labeled I indicates the position within the intermediate zone 438. The point labeled P indicates a position within the peripheral zone 440. The number following the letters “C”, “I”, or “P” indicates the relative face position.

  Using the defined point cloud, the ultrasonic device 450 (shown in FIG. 13) can be used to map the thickness profile of the face 416. The point cloud approach has the advantage that it can capture the presence of discontinuous variations in face thickness, such as ribs and discontinuous thickness changes. One preferred ultrasonic measurement device is the Panametric model 25DL ultrasonic thickness device 455 and the Panametric model M208 probe 460. Sensors or devices 455 and probes or transducers 460 are manufactured by Panametric, Inc. Commercially available from Waltham, MA.

  Referring to FIG. 12, the face thickness data obtained from the ultrasound device is used with the material modulus information to define a central, intermediate and, where appropriate, peripheral zone. The central zone 436 is defined by constructing a region that includes a certain percentage of the total face surface area and encloses the geometric center. Point cloud thickness data within the defined zone is averaged or divided into individual elements within the zone. If the latter is required, the area percentage for the elements in the zone is calculated. The flexural stiffness of the central and adjacent zones 436 and 438, which was outlined above and the FS calculation was next performed, is determined.

The following example illustrates this technique. In Table 4, random face thickness measurements are made for a titanium alloy club 410 (shown in FIG. 12) with an unknown face thickness profile. The method described above is used.

  FIG. 12 shows measured data points and predicted central, intermediate and peripheral zones 436, 438 and 440. Based on these predicted regions, the percentage of each zone can be more accurately estimated or calculated by other techniques such as face scanning. This data defines three zones. That is, an actual central zone with an average thickness of 0.131 inches; an actual intermediate zone with an average thickness of 0.099 inches; an actual peripheral zone with an average thickness of 0.114 inches. Further, the area of the central zone is estimated to have about 23 percent of the total face surface area, and the area of the peripheral zone is estimated to have about 35 percent of the total face surface area. Based on this information, the bending stiffness can be calculated as shown below.

  In connection with the calculation of face bending stiffness and non-bending stiffness, all of the above examples and point clouds assume that the striking face has isotropic material properties and symmetry with respect to the central surface of the face structure. Material isotropy, however, is not an essential requirement of the present invention. The invention may also include an anisotropic material head. Bending stiffness or bending stiffness ratio can also be used in the context of anisotropic structures. These calculations are still applicable, but take a more general form as discussed below.

The calculation of bending stiffness is simplified by the symmetrical notation associated with the central surface of the face. Calculation of bending stiffness for asymmetric shells relative to the central surface is common in composite structures where Laminate Shell Theory is applicable. The Kirchhoff shell assumption can be applied here. Referring to FIG. 14, an asymmetric isotropic laminate 500 is shown and there are N sheets or layers 502. Furthermore, the laminate has a thickness t as described, x _i is the directed distance also coordinates according to Figure 14. By definition, the positive direction is downward, laminate, points to the directed distance x _i of the k-th stack layer at the bottom. For example, x ₀ = −t / 2 and x _N = + t / 2 for a stack of N layers with thickness t.

である。 When a thin plate is constructed from a plurality of materials M, it becomes more complicated. In this case, the area percentage Ai is included in the individual summation across the sheet, as before, in the bending stiffness calculation. The most common way to calculate the bending stiffness of this case is as described above,

It is.

ここで、ｘ_０＝−ｔ／２，ｘ_１＝ｔ／２−ＷＩ，ｘ_２＝ｔ／２であり、置換すると、

となる。ｔ＝０．１２５であると、ＷＩ＝０。０８３であり、ゾーンのＦＳは３，７４５ｌｂ・ｉｎである。ただし、スチール層の厚さはチタン層の厚さの約１／２である。 Asymmetry arises due to the thin plate geometry around the central surface. That is, the laminate lacks material symmetry around the central layer of the laminate. However, this asymmetry does not change the calculated value of the bending stiffness, which causes forces and moments in the laminate under an applied load. Examples of this type of configuration, a titanium alloy face of the first elastic modulus E _t in a uniform thickness, and lined with steel members of the second elastic modulus E _s of the thickness of half the width of the titanium part to the central zone It will be a thing. In this example, the bending stiffness is approximated by a simplified formula and is as follows.

Where x ₀ = −t / 2, x ₁ = t / 2−WI, x ₂ = t / 2,

It becomes. When t = 0.125, WI = 0.083 and the FS of the zone is 3,745 lb · in. However, the thickness of the steel layer is about ½ of the thickness of the titanium layer.

  Referring to FIG. 15, a test apparatus 650 for measuring inertance is schematically shown. In general, inertance is a frequency response. More specifically, inertance is a measure of the stiffness of a structure, in this example a club face, at various vibration frequencies. The unit of inertance is the unit of acceleration over the unit of force. The preferred first resonance frequency of the face of the present invention is located at the point where the inertance is maximized.

  The test device 650 includes a club head 652, a rigid mass 654, an accelerometer 656 and an impact hammer 658. The mass 654 is preferably a 1 inch diameter cylindrical steel rod. Referring to FIGS. 15 and 15A, the mass 654 is preferably provided with a cylindrical cavity 659 at one end to receive an accelerometer 656 and a slot 660 for holding a cable 662. The accelerometer 656 is placed at the geometric center of the face of the club head 62 at a high modulus adhesive, such as a cyanoacrylate adhesive, Lactite Corp. Bound by Lactite available from Newington, CT. The mass 654 is then placed on the accelerometer 656 and secured to the club face with a cyanoacrylate adhesive. The total mass of mass 654 and accelerometer 656 should be equal to the mass of the golf ball, ie 1.62 ounces. The impact mamma 658 has an integral force transducer 658a and is reciprocable with respect to the free end 654a of the rigid mass as indicated by arrow I and is coupled at its geometric center of the club head. Hit 654. The collision force or excitation force is perpendicular to the club head and is transmitted to the striking face via the mass body 654 at the time of collision.

The test apparatus further includes a connection box and ICP power source 660, and a cable 662 that connects the accelerometer 656 and impact hammer transducer 658a. The connection box and ICP power supply 660 is further connected to a digital signal processing board 664, which is located in a computer 665 with signal processing software 667. The digital signal processing board 664, computer 665 and software 667 are used to adjust the frequency signal and calculate the frequency response function. The accelerometer 656, transducer 658a, connection box and ICP power supply 660, cable 662, digital signal processing board 664, computer 665 and software 667 are commercially available and those skilled in the art can easily use these components to obtain inertance values. It can be acquired by identification. Typically, data from 20 collisions is averaged to reduce noise and improve measurement accuracy. Table 5 below lists specific model numbers for the vibration device shown in FIG.

Referring to FIG. 16, a graph of inertance versus frequency for a conventional club head is shown. A conventional golf head is an 8 ° loft Callaway Great Big Bertha War Bird. The inertance I shown is the result of a test using the device 650 of FIG. The point I ₁ of the frequency of 3330 Hz is the first main resonance frequency, and is the point where the first main maximum inertance of the inertance function I occurs. One maximum value does not represent the main resonance natural frequency of the face, but is also represented as point I ₂ at a frequency of 2572 Hz in FIG. This second maximum value I ₂ is characterized by the described inertance transition of less than 10 decibels. This second maximum may be due to vibrations of the crown, sole or skirt that do not move perpendicular to the face of the club face. The second maximum value is not correlated with the COR and the ball measure because the vibration response is numerically small and does not match the ball response. The COR of the tested normal club head was measured according to USGA, Rule4-1e Appendix II, 2nd edition, February 8, 1999 and found to be 0.785. A preferred first main resonance frequency of vibration is defined by the following relationship:
1 / (2 × contact period) <I ₁ <3 / (2 × contact period)
The contact period is the time interval during which the ball is in contact with the club face. In a typical driver collision, the contact period is 500 microseconds (500 × 10 ⁻⁶ seconds). Thus, the preferred main resonant frequency of club head vibration is between about 1000 and 3000 Hz. The closer the contact time is to the lower limit, the greater the COR, resulting in a higher rebound ball speed. More preferably, the first type resonance frequency is less than 2900 Hz.

  FIG. 17 shows the inertance function of the club head of the present invention. The first main resonance frequency was 2632 Hz, and the COR of the club of the present invention was measured as 0.824. The COR of the club of the present invention is larger than that of the conventional club shown in FIG.

  Several club head examples were made using two commercially available titanium alloys 6AL-4V and SP700. Clubs were manufactured with various uniform face thicknesses. FIG. 18 shows that the COR increases linearly with decreasing face thickness for a given security alloy. However, different titanium alloys having slightly different elastic moduli have completely different trend lines, and it is difficult to predict COR with a thickness alone. FIG. 19 shows a plot of COR versus first main resonance frequency for the same set of club heads as in FIG. FIG. 18 occupies the first main resonance frequency predicting COR independently of the titanium alloy. The first main resonance frequency of the club head can be used as a quality control element to comply with USGACOR regulations.

  According to another embodiment of the invention, as shown in FIGS. 20-23, the striking face 16 is divided into two or more non-concentric regions having different bending stiffnesses. The club head 510 has a toe 18, a heel 20, a sole plate 22, a hosel 24, a crown 28 and a rear portion, and is similar to the other club heads of the present invention described above. The club head 510 further has a striking face 516 that has an upper or crown face portion 520 and a lower or sole base portion 522. Club head 510 may also optionally include a peripheral portion 540. Preferably, the bending stiffness of the crown face portion 520 is different from the bending stiffness of the sole face portion 522.

  According to one aspect, the bending stiffness of the crown face portion 520 is preferably about ½ that of the sole face portion 522. In other words, the bending stiffness of the striking face 516 changes, and more specifically increases from the crown 28 toward the sole 22. When the golf ball hits the golf ball just at or near the center, the crown face portion 520 deforms more greatly than the sole face portion 522 due to its lower bending stiffness when the striking face deforms. Due to such a shift in deformation, the launch angle of the golf ball becomes larger than that when a similar golf club is used at a similar club loft angle except for a change in bending rigidity from the crown to the sole.

  The increase in golf club launch angle achieved by changing the bending stiffness from the crown to the sole depends on a number of factors including the impact position of the striking face and the bending stiffness of the impact location. Conversely, by changing the bending stiffness from the crown to the sole, that is, by making the bending stiffness of the crown face portion 520 larger than that of the sole face portion 522, the launch angle of the golf ball can be reduced. . In this embodiment, since the sole face portion is deformed more than the crown face portion, the launch angle is reduced.

Preferably, the bending stiffness (Et ³ ) of the crown face portion 520 of the striking face 516 is between about 8,500 lb · in and 60,000 lb · in, and the bending stiffness of the sole face portion 522 is that of the crown face portion 520. Is approximately twice (200%) or less, thereby increasing the launch angle of the golf ball. On the other hand, the bending stiffness of the sole face portion 522 is about ½ (50%) or more than the bending stiffness of the crown face portion 520, thereby reducing the launch angle of the golf ball. Suitable ratios of flexural rigidity between the parts include 4: 1, 1: 4, 2: 3, 3: 2.

  According to another aspect of the present invention, as shown in FIG. 21, the striking face 516 of the club head 510 has a heel face portion 524 and a toe face portion 526, and the bending rigidity of the striking face 516 is from heel to toe. Change direction. Similar to the embodiment shown in FIG. 20, the striking face is selectively and partially deformed to direct the angle of the golf ball in the desired lateral direction. More specifically, when the bending stiffness of the heel face portion 524 is less than the bending stiffness of the toe face portion 526 with respect to a collision just at or near the center, the heel face portion 524 is more deformed and the golf ball is Orient the left hand of the right-handed golfer to compensate for the tendency to slice or hook the ball to the right. On the other hand, when the bending stiffness of the toe face portion 526 is less than the bending stiffness of the heel face portion 524, the toe face portion 526 is more deformed to direct the golf ball to the right side of the right-handed golfer's body and the ball to the left side Compensate for the tendency to slice or hook.

Preferably, the bending stiffness (Et ³ ) of the heel face portion 524 of the striking face 516 is between about 8,500 lb · in and 60,000 lb · in, and the bending stiffness of the toe face portion 526 is that of the heel face portion 524. About twice (200%) or less, thereby directing the golf ball to the left. On the other hand, the bending stiffness of the toe face portion is about 1/2 (50%) or more than the bending stiffness of the heel face portion, thereby directing the golf ball to the right. Suitable ratios of flexural rigidity between the parts include 4: 1, 1: 4, 2: 3, 3: 2.

  According to another aspect of the present invention, the advantages of the striking face shown in FIGS. 20 and 21 can be realized with a single striking face as shown in FIG. Here, the striking face 516 has four parts: a crown-heel part 528, a crown-toe part 530, a sole-toe part 532 and a sole-heel part 534. The bending stiffness of the striking face 516 varies both in the direction from the crown to the sole and from the heel to the toe. In either direction, the bending stiffness may increase or decrease. Therefore, the advantage of deflecting the vertical launch angle of the golf ball and the lateral direction of the flight can be realized with a single golf club head.

Preferably, the bending stiffness (Et ³ ) of the crown-heel portion 528 is between about 8,500 lb · in and 60,000 lb · in. The bending stiffness of the crown-toe portion 530 is preferably about 70% to about 130% of the bending stiffness of the crown-heel portion 528. The bending stiffness of the sole-toe portion 532 is preferably about 50% to about 130% of the bending stiffness of the crown-heel portion 528. The bending stiffness of the sole-heel portion 534 is preferably about 70% to about 200% of the bending stiffness of the crown-heel portion 528.

  Alternatively, the striking face 516 may include two or more non-concentric portions that constitute a normal or unusual shape, such as the embodiment shown in FIG. Further, the boundaries between non-concentric regions need not be substantially vertical or substantially horizontal.

  The obvious advantage of this embodiment is that it reduces the manufacturing cost of the golf ware. By changing the bending stiffness of the striking face according to the present invention, multiple lofts can be cured with a predetermined head club design at a fixed loft angle. A single molding facility can be used with a variety of face cavity inserts to produce a family of club heads that are effectively different from the loft angle while having the same external loft angle.

According to another embodiment of the present invention, the advantages of the embodiment shown in FIGS. 1-19, namely, a rigid central portion 36, 136, 236, 336 or 436 and a relatively flexible central portion 38, 138. 238, 338 or 438, and the intermediate portion is deformed upon impact to achieve a high initial velocity, while the central portion is not substantially deformed and the ball flies without detaching from the target (FS _c / FS ₁ > = 3) etc. can be combined with the advantages of the embodiment shown in FIGS. 20-23, ie vertical or horizontal control of the flight of the ball. As shown in FIGS. 24-25, the golf club head 610 has a striking face 616 that has a central portion 36, 136, 236, 336 or 436 that includes a crown intermediate portion 620 and a sole intermediate portion 622. Surround with the middle part including. The face 616 may optionally include a peripheral region (not shown). Preferably, the flexural rigidity ratio between any portion of the central region and the intermediate region is greater than or equal to about 3.0, more preferably between about 6.0 and about 12.0. In other words, the ratio between the central region and the crown intermediate portion 620 and between the central region and the sole intermediate portion 622 is greater than or equal to about 3.0, more preferably between about 6.0 and about 12.0. It is.

  In this embodiment, the bending stiffness of the two intermediate portions 620 and 622 are preferably different. The crown middle portion 620 may have a lower bending stiffness than the sole middle portion 622 and vice versa, depending on the desired launch angle of the ball. In one non-limiting example, the ratio of flexural rigidity between the central portion and the crown intermediate portion 620 is about 9.0, while the ratio between the central portion and the sole intermediate portion 622 is about 6. 0 and controls the launch angle of the golf ball.

On the other hand, in order to control the launch angle in the lateral direction of the golf ball while maintaining a high initial velocity with a flexural rigidity ratio of (FS _c / FS ₁ > = 3), as shown in FIG. May have a central portion 36, 136, 236, 336 or 436 and a heel intermediate portion 624 and a toe intermediate portion 626. Preferably, the flexural rigidity ratio between any portion of the central region and the intermediate region is greater than or equal to about 3.0, more preferably between about 6.0 and about 12.0. In other words, the ratio between the central region and the heel middle portion 624 and between the central region and the toe middle portion 626 is greater than or equal to about 3.0, more preferably between about 6.0 and about 12.0. Or greater than about 12.0.

  In this embodiment, preferably the bending stiffness of the two intermediate portions 624 and 626 are different. The heel middle portion 620 may have a lower bending stiffness than the toe middle portion 622 and vice versa, depending on the desired lateral launch angle of the ball. In one non-limiting example, the ratio of flexural rigidity between the central portion and the heel intermediate portion 620 is about 9.0, while the ratio between the central portion and the toe intermediate portion is about 6.0. It controls the launch angle in the lateral direction of the golf ball.

  According to another aspect of the invention, similar to the embodiment shown in FIG. 22, the striking face 616 has a central region and, as described above, four parts: a crown-heel part 528 and a crown-toe part 530. , And an intermediate region consisting of a sole-toe portion 532 and a sole-heel portion 534. Each intermediate portion preferably has a different bending stiffness to control the launch and lateral angle of the golf ball. Further, the flexural rigidity ratio between the central region and each intermediate portion is greater than or equal to about 3.0, and more preferably between about 6.0 and about 12.0.

Preferably, the bending stiffness (Et ³ ) of the crown-heel portion 528 is between about 8,500 lb · in and 60,000 lb · in. The bending stiffness of the crown-toe portion 530 is preferably about 70% to about 130% of the bending stiffness of the crown-heel portion 528. The bending stiffness of the sole-toe portion 532 is preferably about 50% to about 130% of the bending stiffness of the crown-heel portion 528. The bending stiffness of the sole-heel portion 534 is preferably about 70% to about 200% of the bending stiffness of the crown-heel portion 528.

  While the present invention has been described in various ways, it should be understood that the various features of each embodiment may be used alone or in combination. Accordingly, the present invention is not limited to the specific preferred embodiments described herein. Furthermore, it should be understood that variations and modifications can be made by those skilled in the art to which the present invention pertains within the spirit and scope of the present invention. For example, the change in the thickness of the face and / or individual parts may be stepwise or continuous. Other modifications include a peripheral portion having a thickness that is greater or less than an adjacent intermediate portion. Further, the shapes of the central, intermediate and peripheral portions are not limited to those disclosed herein. Accordingly, all suitable modifications that can be made by those skilled in the art from the contents individually disclosed as based on the scope and spirit of the present invention are included as further embodiments of the present invention. The scope of the invention is thus defined and shown in the examples.

1 is a front perspective view of a toe side of a first embodiment of a golf club head of the present invention. FIG. 2 is a rear perspective view of a heel side of the golf club head of FIG. 1. It is a front view of the golf club head of FIG. FIG. 4 is a cross-sectional view taken along line 3A-3A of the face of the golf club head of FIG. FIG. 4 is a cross-sectional view of the face of the golf club head of FIG. 3 taken along line 3B-3B. FIG. 2 is a plan view of the golf club head of FIG. 1. FIG. 2 is a bottom perspective view of the golf club head of FIG. 1. It is a front perspective view by the side of the toe of 2nd Example of the golf club head of this invention. FIG. 7 is a front view of the golf club head of FIG. 6. FIG. 8 is a cross-sectional view taken along line 7A-7A of the face of the golf club head of FIG. FIG. 8 is a cross-sectional view taken along line 7B-7B of the face of the golf club head of FIG. It is a front perspective view by the side of the toe of 3rd Example of the golf club head of this invention. FIG. 9 is a front view of the golf club head of FIG. 8. FIG. 10 is a cross-sectional view taken along line 9A-9A of the face of the golf club head of FIG. 9; It is a front perspective view by the side of the toe of 4th Example of the golf club head of this invention. FIG. 11 is a front view of the golf club head of FIG. 10. FIG. 12 is a cross-sectional view taken along 11A-11A of the face of the golf club head of FIG. It is an enlarged front view of a golf club head showing an ultrasonic thickness measurement position. It is a schematic diagram of the apparatus which performs ultrasonic thickness measurement on the face of a club head. FIG. 3 is an enlarged elevation view of a part of the face of the laminated golf club head of the present invention. It is a schematic diagram of the test apparatus which acquires frequency response data from a club head. FIG. 16 is a perspective view of a mass body that is used together with the test apparatus of FIG. 15. 4 is a graph of inertance versus frequency for a conventional club head. 4 is a graph of inertance versus frequency for a club head of the present invention. 2 is a graph of COR versus thickness for two alternative titanium alloys. 2 is a graph of COR versus first resonance frequency for two alternative titanium alloys. It is a front view of the other Example of this invention. It is a front view of the other Example of this invention. It is a front view of the other Example of this invention. It is a front view of the other Example of this invention. It is a perspective view of the other Example of this invention. It is a front view of the other Example of this invention. It is a front view of the other Example of this invention.

Claims (25)

  A golf club head adapted to be attached to a shaft and having a striking face, the striking face having a direction control portion, the direction control portion having two or more zones having different bending stiffnesses; A golf club head characterized in that when the hitting face hits a golf ball, the zone is deformed to a different degree to selectively control the flight direction of the ball.   The striking face further includes a central portion disposed within the direction control portion, the central portion including a geometric center of the striking face, and a bending rigidity of the central portion is a bending rigidity of the direction control portion. The golf club head of claim 1, wherein the golf club head is at least about three times greater than.   The golf club head of claim 2, wherein the bending stiffness of the central portion is at least about 6 times greater than the bending stiffness of the directional control portion.   The golf club head of claim 3, wherein the bending stiffness of the central portion is at least about 12 times greater than the bending stiffness of the directional control portion.   3. The golf club head of claim 2, further comprising a peripheral portion disposed around the direction control portion, wherein the peripheral portion has a bending stiffness greater than at least about twice the bending stiffness of the direction control portion.   The golf club head of claim 1, further comprising a peripheral portion disposed around the direction control portion, wherein the bending stiffness of the peripheral portion is greater than at least about twice the bending stiffness of the direction control portion.   The golf club head of claim 1, wherein the first zone of the two or more zones has a flexural rigidity between about 8,5000 lb.in and about 60,000 lb.in.   8. The golf club head according to claim 7, wherein the bending rigidity of the second zone of the two or more zones is about 0.5 to about 2 times the bending rigidity of the first zone.   8. The golf club head according to claim 7, wherein a bending stiffness of a third zone of the two or more zones is about 0.7 times to about 1.3 times a bending stiffness of the first zone.   8. The golf club head according to claim 7, wherein a bending rigidity of a fourth zone of the two or more zones is about 0.7 to about 2 times a bending rigidity of the first zone.   The golf club head of claim 1, wherein the direction control portion has an upper crown zone and a lower heel zone.   The golf club head of claim 1, wherein the direction control portion has a side heel zone and a side toe zone.   The golf club head according to claim 1, wherein the direction control portion includes four zones, and the zones are divided by a vertical center line and a horizontal center line of the hitting face.   The golf club head according to claim 1, wherein the hitting face includes a laminated material.   The golf club head according to claim 2, wherein the hitting face includes a laminated material.   A golf club head adapted to be attached to a shaft and having a striking face, the striking face having a central portion and an intermediate portion surrounding the central portion, the central portion being a geometric center of the striking face A golf club head characterized in that the central portion and the intermediate portion have different bending stiffnesses so that the central portion is not substantially deformed after the golf ball collides.   The golf club head according to claim 16, wherein the intermediate portion is deformed after the golf ball collides.   The golf club head of claim 16, wherein the flexural rigidity of the central portion is at least about 3 times greater than the flexural rigidity of the intermediate portion.   The golf club head of claim 18, wherein the bending stiffness of the central portion is at least about 6 times greater than the bending stiffness of the intermediate portion.   The golf club head of claim 19, wherein the flexural rigidity of the central portion is at least about 12 times greater than the flexural rigidity of the intermediate portion.   A golf club head adapted to be attached to a shaft and having a striking face, the striking face having a central portion and an intermediate portion, the central portion including the geometric center of the striking face, the central portion A golf club head, wherein the portion and the intermediate portion have different bending stiffnesses so that the central portion can move inward and outward of the outer surface of the striking face after a golf ball impact.   The golf club head according to claim 21, wherein the intermediate portion is deformed after the golf ball collides.   The golf club head of claim 21, wherein the flexural rigidity of the central portion is at least about 3 times greater than the flexural rigidity of the intermediate portion.   The golf club head of claim 23, wherein the flexural rigidity of the central portion is at least about 6 times greater than the flexural rigidity of the intermediate portion.   25. A golf club head according to claim 24, wherein the flexural rigidity of the central portion is at least about 12 times greater than the flexural rigidity of the intermediate portion.

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