JP4871006B2 - Golf club head - Google Patents

Description

  The present invention relates to a golf club head in which a head body made of a metal material and a crown member made of a fiber reinforced resin are fixed, and more particularly to a golf club head capable of improving durability at a joint portion between both members.

  In recent years, a so-called composite type hollow golf club head composed of a metal material and a fiber reinforced resin has been proposed. For example, as shown in FIG. 11, the following Patent Document 1 includes a head main body b made of a metal material having an opening in a crown portion, and a fiber reinforced resin disposed in the opening to close the head body b. A golf club head d including a crown member c is disclosed.

  The club head d can twist a large weight margin from the crown due to the small specific gravity of the crown member c. Then, by allocating the weight margin to an appropriate position, for example, the head center of gravity can be positioned lower. Thus, the composite type club head greatly increases the degree of freedom in designing the center of gravity.

Japanese Patent Laid-Open No. 2005 296626

  By the way, when a ball is hit with a club head, a large stress is generated not only in the face portion that is in direct contact with the ball but also in the crown portion connected to the face portion. In particular, in the composite type club head d in which the opening of the crown portion is closed by the crown member as described above, there is a difference in rigidity at the boundary portion j on the face portion side between the crown member and the head body. Stress tends to concentrate, and as a result, the vicinity of the boundary j is a weak point in terms of durability.

The inventors have found that when a ball is hit with a club head, the crown portion is elastically deformed to protrude upward (outward of the head), and a large stress is applied to the boundary portion at each deformation. I found out. And in order to reduce such a stress, it turned out that it is effective to make the radius of the outer surface of the crown part which forms boundary part j vicinity larger than the radius of the curved surface before and behind that.

  As described above, the present invention provides a golf club head capable of improving the durability at the joint portion between both members, based on the limitation of the outer surface shape of the region in the vicinity of the boundary point centered on the boundary point. The purpose is to do.

The invention according to claim 1 of the present invention includes a face portion having a face for hitting a ball on the front surface, and a crown portion extending from the upper edge of the face to the back face side to form a head upper surface, A wood-type golf club head having a head volume of 360 to 470 cm ³ provided with a hollow portion, and made of a metal material and provided with an opening portion having an opening area of 20 to 80 cm ² in the crown portion Including a head body and a crown member made of fiber reinforced resin disposed in the opening and closing the opening, and in a reference state placed on a horizontal plane at a specified lie angle and loft angle, The outer surface of the crown portion on the head cutting surface passing through the face side position and parallel to the head longitudinal direction is from the upper edge of the face. Tsu to de rear has a boundary point of the face side of the head main body and the crown member at a position spaced 10 to 50 mm, and the head longitudinal direction around the boundary point of the face side of the outer surface of the crown portion The region near the boundary point, which is an 18 mm region, is formed by a smooth curve that is convex upward, and satisfies the following relationship.
Rc> Rf1 and Rc> Rb1.

  Here, “Rc” is a boundary point on the face side, a first front side point that separates 3.0 mm from the boundary point on the face side to the head front side, and a boundary point on the face side from the boundary point on the face side to the head rear side. The radius of the intermediate arc consisting of a single arc passing through three points with the first rear point separating 0 mm. Further, the “Rf1” is a single arc passing through three points of the boundary point on the face side, the first front side point, and the second front side point that is separated from the first front side point by 3.0 mm to the head front side. The radius of the first front arc is Further, the “Rb1” includes three points of the boundary point on the face side, the first rear side point, and the second rear side point that is separated from the first rear side point by 3.0 mm to the head rear side. Let it be the radius of the first rear arc consisting of a single arc passing through.

The invention according to claim 2 is the golf club head according to claim 1, wherein the boundary point vicinity region satisfies the following relationship.
Rf1> Rf2 and Rb1> Rb2

  Here, the “Rf2” is a single passing through the first front point, the second front point, and the third front point that is 3.0 mm from the second front point to the front of the head. This is the radius of the second front arc composed of arcs. The “Rb2” includes three points, the first rear point, the second rear point, and a third rear point that is separated from the second rear point by 3.0 mm from the second rear point to the head rear side. Is the radius of the second rear arc consisting of a single arc passing through.

  The invention according to claim 3 is the golf club head according to claim 1 or 2, wherein the radius ratios (Rc / Rf1) and (Rc / Rb1) are 1.02 to 2.00.

  A fourth aspect of the present invention is the golf club head according to the second aspect, wherein the radius ratios (Rf1 / Rf2) and (Rb1 / Rb2) are 1.02 to 2.00.

  According to a fifth aspect of the present invention, in the vicinity of the boundary point, the radius of curvature continuously decreases from the boundary point toward the head front side and the head rear side, respectively. The golf club head described.

  According to the first aspect of the present invention, there is a face-side boundary point between the head main body and the crown member at a position at least 10 mm behind the upper edge of the face on the outer surface of the crown portion. Therefore, the boundary point can be moved away from the upper edge of the face to the rear of the head, and the impact stress at the time of hitting the ball acting on the boundary point can be reduced.

In addition, an area near the boundary point, which is an 18 mm area in the head front-rear direction centering on the boundary point on the face side of the outer surface of the crown portion, is formed by a smooth curve that protrudes upward, and Satisfy the relationship.
Rc> Rf1 and Rc> Rb1

  Here, Rc is a radius of a curved surface in a range of 3.0 mm before and after the boundary point, and Rf1 is a radius of a curved surface in a range of 6.0 mm forward from the boundary point. Rb1 approximately represents the radius of the curved surface in the range of 6.0 mm behind the boundary point. Then, as described above, by making the radii Rf1 and Rb1 on both sides smaller than the radius Rc, the stress is distributed to the portion with a large curvature before and after the boundary point, and thus the stress or strain acting on the boundary point is reduced. Yes.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a reference state of a golf club head (hereinafter, simply referred to as “head” or “club head”) 1 of the present embodiment, FIG. 2 is a plan view thereof, and FIG. 3 is A in FIG. FIG. 4 is an exploded perspective view of the club head 1.

  The head 1 of this embodiment includes a face portion 3 having a face 2 that is a surface for hitting a ball, a crown portion 4 extending from the upper edge 2a of the face 2 to the back face BF side, and forming a head upper surface. The sole portion 5 that is continuous with the lower edge 2b of the face 2 and extends to the back face BF side to form the bottom surface of the head, and the crown portion 4 and the sole portion 5 are connected to each other and back from the toe side edge 2c of the face 2 A side portion 6 that passes through the face BF and extends to the heel side edge 2d, and a hosel portion 7 that is provided on the heel side of the crown portion 4 and has a shaft insertion hole 7a to which one end of a shaft (not shown) is attached. Yeah. Further, as shown in FIG. 3, the club head 1 has a hollow structure in which a hollow portion i is provided, and in this embodiment, a wood type such as a driver (# 1) or a fairway wood is shown.

  Here, the reference state of the club head 1 means that the axial center line CL of the shaft insertion hole 7a is arranged in an arbitrary vertical plane VP1 and is inclined at the lie angle with respect to the horizontal plane HP, and the face 2 is The head 1 is brought into contact with the horizontal plane HP by being tilted with respect to the vertical plane VP1 at a loft angle (which is a real loft angle and the same shall apply hereinafter). Unless otherwise specified in the present specification, the head 1 is described as being placed in a reference state.

  Further, as shown in FIG. 2, the head longitudinal direction is defined as a direction Fb parallel to a straight line obtained by projecting a normal line N raised from the head center of gravity G to the face 2 onto the horizontal plane HP, and from a certain arbitrary point. Relative to each other, the face 2 side is the front (or front side), and the back face BF side is the back (or rear side). The intersection SS between the normal N and the face 2 is called a sweet spot.

  The head width direction is a direction parallel to a direction perpendicular to the head longitudinal direction on the horizontal plane HP.

The club head 1, although 3 60cm ³ or more, more preferably it is desirable to have a 380 cm ³ or more by volume. Such a large volume is useful for increasing the moment of inertia and the center of gravity depth of the head 1. On the other hand, too large a volume of the club head 1, the increase in head weight, deterioration of swing balance, because of a problem such as a reduction and the golf rule violation durability, and 4 70cm ³ or less, more preferably 460 cm ³ or less Is desirable.

  The total weight of the club head 1 is preferably 170 g or more, more preferably 180 g or more in consideration of swing balance and the like. On the other hand, the upper limit is preferably 250 g or less, more preferably 240 g or less. In the case of a head, 200 g or less is desirable. If the total weight of the club head 1 is too small, it is difficult to feel the weight of the head during the swing, the timing becomes difficult to take, and the resilience tends to decrease and the flight distance tends to decrease. On the contrary, if the total weight of the head becomes too large, the club cannot be completely shaken, and the flight distance and the direction stability are likely to deteriorate.

  The club head 1 includes a head main body 1A made of a metal material and provided with an opening O in the crown portion 4, and a crown member 1B made of a fiber reinforced resin disposed in the opening O and closing the opening O. These are joined and configured.

  The metal material forming the head main body 1A is not particularly limited, but preferably stainless steel, maraging steel, pure titanium, a titanium alloy, or the like is desirable.

  In the present embodiment, the opening O is accommodated in the region without protruding from the crown portion 4. As a result, the head main body 1A according to the present embodiment is arranged around the opening O in the face part 3, the sole part 5, the side part 6, the hosel part 7 and the crown part 4, as shown in FIG. And a crown edge 10 to be formed. However, it goes without saying that the opening O may be provided so as to straddle the crown portion 4 and the side portion 6, for example.

  Such a head main body 1A can be made by forging, casting, or joining two or more bent products such as rolled material, but preferably a single cast product in which each part is integrally formed in advance ( More specifically, it is desirable to be formed by a lost wax precision casting product). Thereby, the productivity of the head 1 is improved.

The contour shape of the opening O is not particularly limited. However, in order to prevent the concentration of stress and the like, it is desirable that the contour is formed with a smooth curve substantially along the contour of the crown portion 4 as in this embodiment. . Moreover, since the opening part O is closed with the crown member 1B which consists of fiber reinforced resin with small specific gravity, the weight of the crown part 4 can be reduced depending on the area. Therefore, in order to obtain a sufficient weight margin from the crown portion 4, the area of the opening O is, 2 0 cm ² or more at but, more preferably 40 cm ² or more, more preferably 50 cm ² or more. On the other hand, in order to ensure durability at the crown portion 4, the area of the opening O is 80 cm ² or less, and more preferably 70 cm ² or less. The area of the opening O is calculated as the opening area projected on the horizontal plane HP in the plan view of the head 1 in the reference state, as shown in FIG.

  As shown in FIG. 3, the crown edge portion 10 is provided with a main portion 11 that substantially forms an outer surface 4 a (finished surface) of the crown portion 4, and is provided in a stepped manner from the outer surface 4 a and is crowned. 1B of inner surface 1Bi of 1B and the receiving part 12 which overlaps and supports a peripheral part. The inner surface 1Bi of the crown member 1B is a surface facing the hollow portion i side of the head 1.

  In the present embodiment, both the main portion 11 and the receiving portion 12 are continuously provided in an annular shape around the opening O. Accordingly, the peripheral edge 1Be of the crown member 1B is moved away from the ridge line portion between the crown portion 4 and the side portion 6 of the head 1, and this helps to prevent stress concentration on the peripheral edge 1Be.

  The receiving portion 12 is configured so that the outer surfaces of the crown member 1B and the main portion 11 supported thereon are flush with each other by optimizing the step amount (dent amount) from the outer surface of the main portion 11. Useful for finishing. This simplifies the surface finishing process, such as subsequent polishing, and increases productivity.

  In order to effectively reduce the center of gravity of the head 1, the width RW of the receiving portion 12 overlapping the crown member 1B (measured in a direction perpendicular to the edge of the opening O as shown in FIG. 2). Is preferably 10.0 mm or less, more preferably 5.0 mm or less, and still more preferably 3.0 mm or less. On the other hand, if the width RW is too small, the bonding area between the crown member 1B and the receiving portion 12 is reduced, and the bonding strength may be reduced. From such a viewpoint, the width RW is preferably 1.0 mm or more, more preferably 2.0 mm or more, and further preferably 2.5 mm or more. The width RW of the receiving portion 12 may be constant or may vary.

  Further, in order to ensure the durability of the crown portion 4 and the moldability of the head main body 1A, the thickness t1 (shown in FIG. 7) of the main portion 11 is preferably 0.50 mm or more, more preferably 1 0.0 mm or more, more preferably 1.5 mm or more. On the other hand, when the thickness t1 of the main portion 11 is increased, the weight of the crown portion 4 tends to increase. Therefore, the thickness is preferably 2.0 mm or less, more preferably 1.7 mm or less.

  Similarly, if the thickness t2 of the receiving portion 12 is too small, the strength may be insufficient and breakage or deformation may occur. If the thickness t2 is too large, a sufficient weight margin cannot be obtained in the crown portion 4. From this point of view, the thickness t2 of the receiving portion 12 is preferably 0.3 mm or more, more preferably 0.5 mm or more, and further preferably 0.7 mm or more. 5 mm or less, more preferably 1.0 mm or less is desirable.

  The crown member 1B is a composite material of a matrix resin and a fiber that is a reinforcing material thereof, and may have a very small specific gravity compared to a metal material. Therefore, by configuring a part of the crown portion 4 with the crown member 1B made of fiber reinforced resin, a large weight reduction effect can be obtained on the head upper side. As described above, the reduced weight can be used for increasing the size of the head main body 1A and adjusting the position of the center of gravity G of the head.

  The matrix resin is not particularly limited, and examples thereof include thermosetting resins such as epoxy resins and phenol resins, and thermoplastic resins such as nylon resins and polycarbonate resins. The former matrix resin is preferable because it is inexpensive, has good adhesion to fibers, and has a relatively short molding time. Also, the fiber as the reinforcing material is not particularly limited. For example, organic fiber such as carbon fiber, glass fiber, aramid fiber or polyphenylenebenzoxazole resin fiber (PBO fiber), metal fiber such as amorphous fiber or titanium fiber, and the like are used. In particular, a carbon fiber having a small specific gravity and a large tensile elastic modulus is preferable.

The elastic modulus of the fiber is not particularly limited, but if it is too small, the rigidity of the crown member 1B cannot be ensured and the durability tends to decrease. Conversely, if it is too large, the cost increases and the tensile strength tends to decrease. . From such a viewpoint, the elastic modulus of the fiber is 50 GPa or more, more preferably 100 GPa or more, further preferably 150 GPa or more, particularly preferably 200 GPa or more, and the upper limit is preferably 450 GPa or less, more preferably 350 GPa or less. . The elastic modulus of the fiber is a tensile elastic modulus, which is a value measured according to “Carbon Fiber Test Method” of JIS R7601. When two or more kinds of fibers are included, the elastic modulus of each fiber is an average elastic modulus calculated by weighting the weight ratio, as represented by the following formula (1).
Average elastic modulus = Σ (Ei · Vi) / ΣVi (i = 1, 2,...)
(Here, Ei is the elastic modulus of the fiber i, and Vi is the total weight of the fiber i.)

  Further, the crown member 1B can be formed by various methods. For example, the crown member 1B is formed by molding and curing a laminate in which a plurality of uncured or semi-cured prepreg sheets are stacked in a mold or the like by applying heat and pressure in a mold or the like. Can be made. The molded crown member 1B is disposed on the receiving portion 12 of the opening O and is integrally joined to the head main body 1A by, for example, an adhesive.

  Further, the crown member 1B can be molded by using a so-called internal pressure molding method as shown in FIG. 5, for example. In the internal pressure molding method, as shown in FIG. 5A, first, one or a plurality of prepreg sheets 14 are arranged in the opening O of the head main body 1A so as to cover the opening O. 20 is preformed. In addition, for example, a thermosetting adhesive or a resin primer is applied between the prepreg sheet 14 and the receiving portion 12 in advance. Thereby, in the head base | substrate 20, position shift etc. of both members are prevented, and a shaping | molding precision is improved as a result.

  The preformed head base 20 is put into a mold 21 including, for example, a pair of separable upper mold 21a and lower mold 21b. However, the preliminary molding may be performed, for example, in a state where the head main body 1A is mounted on the lower mold 21b. The head main body 1A is provided with a through hole 22 that communicates with the hollow portion i in advance. In this example, although the through-hole 22 is shown, for example, provided in the side part 6, it is not limited to this position. Then, the bladder B is inserted into the hollow portion i from the through hole 22. The bladder B is configured to be able to expand and contract by entering and exiting a pressurized fluid.

  Thereafter, as shown in FIG. 5B, an internal pressure molding step is performed in which the mold 21 is heated and the bladder B is expanded and deformed in the hollow portion i. As a result, the prepreg sheet 14 that has received heat and pressure from the bladder B is deformed along the cavity C of the upper die 21a and is formed into a desired crown member 1B, and its peripheral portion is formed in the receiving portion 12. They are joined together. After forming the prepreg sheet 14, the bladder B is contracted and taken out from the through hole 22. Further, the through hole 22 is closed later by a badge, a cover or the like with a product name or a decorative pattern of the head.

  The thickness t3 (shown in FIG. 7) of the crown member 1B is not particularly limited. However, if the thickness is too small, the strength may be insufficient and durability may be impaired. May not be obtained. From such a viewpoint, the thickness t3 of the crown member 1B is preferably 0.3 mm or more, more preferably 0.5 mm or more, still more preferably 0.7 mm or more, and preferably 2.0 mm or less. Preferably it is 1.5 mm or less, more preferably 1.0 mm or less.

  As shown in FIG. 2, the club head 1 of the present embodiment is a vertical plane (AA in FIG. 2) that passes through the position Pf closest to the face 2 of the crown member 1B and is parallel to the head longitudinal direction Fb. ) At the head cutting surface (this is shown in FIG. 3), the outer surface 4a of the crown portion 4 is at least 10 mm, more preferably 15 mm, more preferably 20 mm from the upper edge 2a of the face 2 to the rear of the head. It is desirable to have the boundary point J on the face side between the head main body 1A and the crown member 1B at positions separated by the distance A described above.

In this way, by moving the boundary point J away from the face 2 to the rear of the head, the stress acting on the boundary point J at the time of hitting the ball is reduced, and as a result, peeling or peeling at the joint between the head body 1A and the crown member 1B is possible. Damage and the like can be effectively prevented. Incidentally, the distance when A is significantly larger, the smaller the area of the opening O provided in the crown portion 4, that can not be adequately reduced weight at the head top side. From this point of view, the distance A is set to 5 0 mm or less, and more preferably at most 40 mm.

  Here, when the upper edge 2a of the face 2 can be identified by a clear ridgeline (edge), it is determined based on the ridgeline. However, when the upper edge 2a of the face 2 is not clear due to an arc or the like, as shown in FIG. 6 (A), the head 1 is cut along a number of planes P1, P2,. obtain. Then, as shown in FIG. 5B, the position Z where the radius of curvature r of the face outer surface contour line Lf is 200 mm for the first time when measured from the sweet spot side toward the outer surface 4a side of the crown portion is Considered edge 2a. The face outer surface outline is defined by filling a face line, a punch mark, and the like.

  Further, the position Pf closest to the face 2 of the crown member 1B is a contact point between the face 2 side edge of the crown member 1B and a vertical plane parallel to the vertical plane VP1 in plan view. When the two-side edge and the vertical surface are in line contact, the intermediate point of the length is determined as the position Pf closest to the face 2 of the crown member 1B.

  In this embodiment, the front edge of the crown member 1B extends smoothly from the position Pf toward the toe side and the heel side while being inclined in a direction away from the upper edge of the face 2. Further, the rear edge of the crown member 1 </ b> B extends smoothly along the boundary between the crown portion 4 and the side portion 6.

  Further, FIG. 7 shows a partially enlarged view near the boundary point J in FIG. In the present invention, on the head cutting surface, the boundary point vicinity region Y, which is an 18 mm region in the head front-rear direction of the outer surface 4a of the crown portion 4 centered on the boundary point J on the face side, is convex upward. Formed with a smooth curve.

  The “smooth curve” means a curve that does not reverse the curvature and has no substantial unevenness. A smooth curve can be formed as a continuous arc, for example.

  Further, in the club head 1 of the present embodiment, the outer surface 4a of the crown portion 4 has a three-dimensional shape, and not only in the head front-rear direction but also in the head cross section along the cross section in the head width direction. It has a smooth curved surface that is convex.

  In such a boundary point vicinity region Y, when the ball is hit, bending deformation occurs in a direction that becomes convex upward. That is, by being sandwiched between the face part 3 tilted backward by the impact force of the hit ball and the side part 6, the boundary point vicinity region Y is compressed, and the curved line protrudes upward, that is, bends upward. Make a transformation.

Further, FIG. 8 schematically shows the boundary point vicinity region Y. The club head 1 of the present embodiment satisfies the following relationship.
Rc> Rf1 and Rc> Rb1

  Here, the reference sign “Rc” is obtained from the boundary point J on the face side, the first front side point f1 that is 3.0 mm from the boundary point J on the face side to the front side of the head, and the boundary point J on the face side. This is the radius of an intermediate arc Ac consisting of a single arc passing through three points, the first rear point b1 separating 3.0 mm on the rear side of the head. The symbol “Rf1” includes a face-side boundary point J, the first front point f1, and a second front point f2 that is separated from the first front point f1 by 3.0 mm to the head front side. This is the radius of the first front arc Af1 made up of a single arc passing through three points. Further, the symbol “Rb1” indicates the boundary point J on the face side, the first rear side point b1, and the second rear side that separates 3.0 mm from the first rear side point b1 to the head rear side. This is the radius of the first rear circular arc Ab1 composed of a single circular arc passing through three points with the side point b2.

  Here, as shown in FIG. 9, a single circular arc passing through the three points D, E and F has a normal K1 passing through the midpoint of the straight line DE connecting the two adjacent points D and E, and other adjacent points. The center is at the intersection O1 with the normal K2 passing through the midpoint of the straight line EF connecting the two matching points E and F. Thus, the radius R can be obtained.

  The boundary point vicinity region Y is formed with a smooth curve and the points J, f1, f2, b1, and b2 are set at small intervals of 3.0 mm, so that the intermediate point formed by a single circular arc. The circular arc Ac approximately represents a curve of the outer surface 4a of the crown portion between the first front point f1 and the first rear point b1. Similarly, the first front arc Af1 approximately represents a curve of the outer surface 4a of the crown portion between the boundary point J and the second front point f2. Further, the first rear arc Ab1 approximately represents a curve of the outer surface 4a of the crown portion between the boundary point J and the second rear point b2.

Therefore, by defining the radii Rc, Rf1 and Rb1 of the intermediate arc Ac, the first front arc Af1 and the first rear arc Ab1 as described above, the curvature is relatively increased before and after the boundary point J. Can be provided, and the stress or strain at the time of hitting the ball is distributed to the portion, and as a result, the strain is distorted in the range between the first front point f1 and the first rear point b1 including the boundary point j. It can be reduced. Therefore, the stress acting on the boundary point J at the time of hitting can be reduced, and the durability of the joint portion between the head main body 1A and the crown member 1B can be improved.

  Here, the radius Rc of the intermediate arc Ac is not particularly limited, but if the radius Rc is too small, the curvature of the boundary point J increases, and there is a possibility that stress relaxation at this portion cannot be effectively achieved. Therefore, it is preferably 50 mm or more, more preferably 70 mm or more. On the other hand, even if the radius Rc is too large, not only the above-described stress dispersion effect reaches a peak, but the outer surface of the crown portion 4 may become flat, resulting in an uncomfortable appearance. From this point of view, the radius Rc can be set to 1000 mm or less, preferably 500 mm or less, more preferably 200 mm or less, and still more preferably 150 mm or less.

  Further, the ratios (Rc / Rf1) and (Rc / Rb1) of the radii are both larger than 1.0, but when these ratios are reduced, stress or strain is dispersed before and after the boundary point J. Since the effect tends to decrease, it is preferably 1.02 or more, more preferably 1.03 or more, further preferably 1.05 or more, and most preferably 1.06 or more. However, if the ratio is excessively large, stress or strain is excessively concentrated on both side portions of the boundary point Jb, and the effect of improving the durability of the joint portion tends not to be obtained sufficiently. From this point of view, the radius ratios (Rc / Rf1) and (Rc / Rb1) are both 2.00 or less, more preferably 1.50 or less, and still more preferably 1.20 or less.

Further, it is desirable that the boundary point vicinity region Y further satisfies the following relationship.
Rf1> Rf2 and Rb1> Rb2

  Here, as shown in FIG. 8, the symbol “Rf2” includes the first front point f1, the second front point f2, and the front side of the second front point f2 of 3.0 mm. Is a radius of a second front arc Af2 formed of a single arc passing through three points with a third front point f3 separating the two. Further, the symbol “Rb2” is a third rear point b1, a second rear point b2, and a third rear portion that separates 3.0 mm from the second rear point b2 to the head rear side. This is the radius of the second rear arc Ab2 formed of a single arc passing through three points with the rear point b3.

  Thus, by defining the outer surface shape of the boundary point vicinity region Y in a wider range, stress or strain can be more effectively distributed before and after the boundary point J, and the durability at the boundary point J can be further improved. .

  Further, the ratios (Rf1 / Rf2) and (Rb1 / Rb2) of the radii are both greater than 1.0, but when these ratios are reduced, stress or strain is dispersed before and after the boundary point J. Since the effect tends to decrease, it is preferably 1.02 or more, more preferably 1.05 or more, further preferably 1.06 or more, and most preferably 1.07 or more. However, if the ratio is excessively large, stress or strain is excessively concentrated on both side portions of the boundary point Jb, and the effect of improving the durability of the joint portion tends not to be obtained sufficiently. From this point of view, the radius ratios (Rf1 / Rf2) and (Rb1 / Rb2) are both 2.00 or less, more preferably 1.50 or less, and even more preferably 1.25 or less.

  From the same viewpoint, the ratio of the radii (Rc / Rf2) and (Rc / Rb2) is preferably 1.03 or more, more preferably 1.05 or more, further preferably 1.06 or more, and most preferably 1. The upper limit is preferably 07 or more, and the upper limit is preferably 2.00 or less, more preferably 1.50 or less, and still more preferably 1.29 or less.

  As a more preferable aspect of the golf club head as described above, as shown in a simplified manner in FIG. 10, the radius of curvature of the boundary point vicinity region Y is from the boundary point J toward the head front side and the head rear side, respectively. A thing that becomes continuously smaller is desirable. As such a curve, for example, an involute curve or the like is suitable. Thus, by continuously changing the radius of curvature, the stress or strain at the time of hitting the ball can be more smoothly distributed before and after the boundary point J, thereby further improving the durability at the boundary point.

  When the curvature radius of the outer surface in the boundary point vicinity region Y is continuously changed, the ratio of the curvature radius Rj at the boundary point J to the curvature radius Rfe at the front end of the boundary point vicinity region Y (Rj / Rfe) In addition, the ratio (Rj / Rbe) between the same radius of curvature Rj and the radius of curvature Rbe at the rear end of the boundary point vicinity region Y is preferably 1.06 or more, more preferably 1.07 or more, and further preferably 1 0.08 or more is desirable. However, if the ratio is excessively large, stress or strain is excessively concentrated on both side portions of the boundary point Jb, and the effect of improving the durability of the joint portion tends not to be obtained sufficiently. From such a viewpoint, the ratio is preferably 2.10 or less, more preferably 1.55 or less, and still more preferably 1.30 or less.

  The club head 1 having the boundary point vicinity region Y as described above can be easily formed by molding with the mold 21 having the molding surface F having the curved surface described above, when manufactured using, for example, an internal pressure molding method. Can be manufactured. Further, if necessary, polishing is performed thereafter. Further, after molding the head main body 1A and the crown member 1B separately and joining them together with an adhesive or the like, the region Y near the boundary point is polished, and in particular, the amount of polishing near the boundary point J is increased. Therefore, it can be easily manufactured by flattening.

A wood type driver head having a head volume of 420 cm ³ was made on the basis of the specifications shown in FIGS. 1 to 4 and Table 1, and its durability was evaluated. The face-side boundary point between the head body and the crown member was provided at a position 20 mm behind the head from the upper edge of the face. Each part has the same specifications except for the shape of the boundary point vicinity region.

The head body was integrally cast using a titanium alloy (Ti 6Al 4V), and then the shape of the opening was unified by NC processing. The details of the specification are as follows.
Opening area: 60cm ²
Main part thickness t1: 1.6mm
Thickness of receiving part t2: 0.8mm
Width of receiving part RW: 3 mm (uniform and continuous in a ring)

The crown member is formed by adhering a laminate of three prepreg sheets to the receiving portion of the opening of the head body with an adhesive, and integrally molding them in the mold (internal pressure Molding method). Each prepreg sheet is a unidirectional prepreg in which long fibers are aligned in one direction, and detailed specifications are as follows.
Prepreg: MR350C 050S manufactured by Mitsubishi Rayon Co., Ltd.
Tensile modulus of prepreg fiber: 294 GPa (carbon fiber)
Prepreg weight per unit area: 58 g / m ²
Resin content of prepreg: 25%
Fiber angle Innermost layer: 90 degrees with respect to head longitudinal direction Intermediate layer: 0 degree with respect to head longitudinal direction Outermost layer: 90 degrees with respect to head longitudinal direction The crown member is substantially 0.8 mm after molding. Finished with a thickness of.

  And the outer surface shape was adjusted by grind | polishing the boundary point vicinity area | region of the club head taken out from the metal mold | die.

Each head is mounted on a carbon shaft MP 300 (hardness: X) made by SRI Sports, and a 45-inch wood type golf club is prototyped. The head is attached to a swing robot made by Miyamae. Adjusting the speed to 50 m / s, repeating a cycle of hitting 500 golf balls at a sweet spot position, a 10 mm distance from the sweet spot to the heel side, and a 10 mm distance from the sweet spot to the toe side. , And evaluated by an actual hit test hitting a total of 4800 balls. Then, the head was observed with the naked eye for every 100 hitting balls and examined for damage. If the head was damaged during the process, the number of hits was displayed.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the heads of the examples had improved durability.

It is a perspective view of the standard state of the head which shows the embodiment of the present invention. FIG. It is AA sectional drawing of FIG. It is a disassembled perspective view of a head. (A), (B) is sectional drawing explaining the internal pressure forming method. (A), (B) is the front view explaining the upper edge of a face, and its sectional drawing. It is a principal part enlarged view of FIG. It is a schematic diagram of the outer surface of a boundary point vicinity area | region. It is a diagram explaining the single circular arc which passes 3 points | pieces. It is a schematic diagram of the outer surface of a boundary point vicinity area | region as embodiment of this invention. It is a top view of the conventional head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Golf club head 1A Head main body 1B Face member 2 Face 3 Face part 4 Crown part 5 Sole part 6 Side part 7 Neck part 10 Crown edge part 11 Main part 12 Receiving part O Opening part J Face side boundary point Pf Crown member Position Rc closest to the face Radius of the intermediate arc Rf1 Radius of the first front arc Rf2 Radius of the second front arc Rb1 Radius of the first rear arc Rb2 Radius of the second rear arc

Claims (5)

A head volume including a face part having a face for hitting a ball on the front face and a crown part extending from the upper edge of the face to the back face side to form the upper surface of the head and having a hollow part inside is 360 to 360 A wood-type golf club head of 470 cm ³ ,
A head body made of a metal material and provided with an opening having an opening area of 20 to 80 cm ² in the crown, and a crown member made of fiber reinforced resin disposed in the opening and closing the opening And in a reference state placed on a horizontal plane with the specified lie angle and loft angle,
The outer surface of the crown portion at the head cutting surface in a vertical plane passing through the position closest to the face side of the crown member and parallel to the head longitudinal direction is a position separated from the upper edge of the face by 10 to 50 mm behind the head. The region near the boundary point, which is an 18 mm region in the head longitudinal direction with the boundary point on the face side of the outer surface of the crown portion as the center, A golf club head characterized by being formed with a smooth curve convex toward the top and satisfying the following relationship.
Rc> Rf1 and Rc> Rb1
(Here, “Rc” is a boundary point on the face side, a first front side point that separates 3.0 mm from the boundary point on the face side to the front side of the head, and a boundary point on the head side of the face side. The radius of the intermediate arc consisting of a single arc passing through three points of the first rear point separated by .0 mm, and "Rf1" is the boundary point on the face side, the first front point and the first point The radius of the first front arc composed of a single arc passing through three points of the second front side that is 3.0 mm from the front point of the head 1 to the front side of the head, and “Rb1” is the radius of the face side A first rear arc consisting of a single arc passing through three points: a boundary point, the first rear point, and a second rear point that is 3.0 mm from the first rear point to the head rear side. Radius) The golf club head according to claim 1, wherein the boundary point vicinity region satisfies the following relationship.
Rf1> Rf2 and Rb1> Rb2
(Here, “Rf2” is a single point passing through the first front point, the second front point, and a third front point that is 3.0 mm from the second front point to the front of the head. The radius of the second front arc composed of one arc, and “Rb2” is the first rear side point, the second rear side point, and the second rear side point to the head rear side. This is the radius of the second rear circular arc consisting of a single circular arc passing through three points of the third rear side separating 3.0 mm.)   3. The golf club head according to claim 1, wherein the radius ratio (Rc / Rf1) and (Rc / Rb1) is 1.02 to 2.00.   3. The golf club head according to claim 2, wherein the radius ratio (Rf1 / Rf2) and (Rb1 / Rb2) is 1.02 to 2.00.   5. The golf club head according to claim 1, wherein a radius of curvature of the boundary point vicinity region continuously decreases from the boundary point toward a head front side and a head rear side.

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