JP2008200118A - Golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability and ball hitting feeling of a golf club head by improving a sole portion. <P>SOLUTION: The golf club head 1 includes a face portion having a face for striking a ball on the front side thereof and a sole portion 5 continued to the lower edge of the face and composing the bottom surface of the head, and is provided with a hollow portion inside, wherein the sole portion 5 is provided with at least two grooves 8A and 8B concaved toward the hollow portion side and extending in different directions to intersect each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a golf club head having a hollow portion therein, and more particularly to a golf club head capable of improving durability, feel at impact and sound at impact by improving a sole portion.

  In recent years, it has been known that a plurality of grooves extending substantially in parallel with the face are provided in a sole portion of a golf club head having a hollow structure (for example, a wood-type club head such as a driver) (for example, see Patent Document 1 below). ). Since such a groove extends in a direction perpendicular to the striking direction, it is expected that the sole portion is deformed with the groove serving as a node at the time of hitting and the impact at the time of hitting is absorbed.

JP 11-155982 A

  However, simply providing a groove extending in parallel with the face as in Patent Document 1 tends to concentrate stress on the bottom of the groove at the time of hitting the ball, which may reduce the durability of the club head. Further, as a result of various investigations, recent golfers tend to prefer a relatively high hitting sound having a peak in the vicinity of 5000 to 6000 Hz.

  The present invention has been devised in view of the above situation, and at least two grooves that are recessed toward the hollow portion and extend in different directions are formed in the sole portion of the club head having a hollow structure. The main object is to provide a golf club head capable of improving the hit feeling and hitting sound without impairing the durability.

  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, a sole portion connected to the lower edge of the face and forming a bottom surface of the head, and a hollow portion is provided inside. In the golf club head, at least two grooves that are recessed toward the hollow portion and extend in different directions from each other are provided in the sole portion.

  According to a second aspect of the present invention, in the golf club head according to the first aspect, the crossing angle of the grooves is 40 to 90 degrees.

  According to a third aspect of the present invention, there is provided the golf club head according to the first or second aspect, wherein the groove includes at least three grooves extending in different directions.

  A fourth aspect of the present invention is the golf club head according to any one of the first to third aspects, wherein a vibration absorbing material made of a viscoelastic material is disposed in at least one groove.

The invention according to claim 5 is the golf club head according to claim 4, wherein the vibration absorbing material has a complex elastic modulus of 2.0 × 10 ^{7 to} 2.0 × 10 ¹⁰ (dyn / cm ² ).

  In the club head of the present invention, at least two grooves that are recessed toward the hollow portion and extend in different directions from each other are provided in the sole portion. Grooves extending in different directions increase the bending rigidity and torsional resistance rigidity of the sole portion in multiple directions as compared to grooves extending in the same direction. This is useful for shifting the hitting sound to a higher frequency band. Further, since the groove extends in at least two directions, it can efficiently absorb multi-directional vibration generated in the sole portion. This improves the feel at impact by relaxing the impact transmitted to the golfer's hand when hitting.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 4, the golf club head (hereinafter, simply referred to as “head” or “club head”) 1 according to the present embodiment is held on a horizontal plane HP while being held at a specified lie angle and loft angle. FIG. 3 is a perspective view of a reference state, a plan view, an enlarged bottom view, and an enlarged sectional view taken along line XX in FIG. 2.

  The club head 1 includes a face portion 3 having a face 2 as a surface for hitting a ball on the front surface, a crown portion 4 connected to the upper edge 2a of the face 2 and forming the upper surface of the face 2, and a lower edge 2b of the face 2 A sole portion 5 that forms a continuous bottom of the head; a side portion 6 that connects between the crown portion 4 and the sole portion 5 and extends from the toe side edge 2c of the face 2 to the heel side edge 2d through the back face BF; And a hosel portion 7 provided on a heel side of the crown portion 4 and to which a shaft (not shown) is attached.

  As shown in FIG. 4, the club head 1 has a hollow structure in which a hollow portion i is provided, and is preferably made as a wood type such as a driver (# 1) or a fairway wood.

The club head 1 is preferably 400 cm ³ or more, more preferably 420 cm ³ or more, more preferably it is desirable to have a 430 cm ³ or more by volume. Thereby, the moment of inertia of the head 1 is increased, and the directionality of the hit ball is improved. On the other hand, even if the volume of the head 1 is too large, the club weight increases, which may lead to deterioration of swing balance and durability, for example, and violates golf rules in official competitions. From such a viewpoint, the volume of the head 1 is preferably 470 cm ³ or less.

  The total weight of the club head 1 is preferably 170 g or more, more preferably 180 g or more. If the total weight of the club head 1 is too small, it is difficult to sense the weight of the head during the swing and it is difficult to take timing, and the resilience is lowered and the flight distance of the hit ball tends to be reduced. On the other hand, if the total weight of the club head 1 becomes too large, the club cannot be completely shaken, and the flight distance and directional stability tend to be lowered. From such a viewpoint, the total weight of the club head 1 is preferably 250 g or less, more preferably 240 g or less.

  The material constituting the club head 1 is preferably a metal material such as titanium, titanium alloy, aluminum alloy, maraging steel, stainless steel or magnesium alloy from the viewpoint of durability and damage resistance. Further, a fiber reinforced resin or the like may be used for a part of the club head 1 in order to optimize the center of gravity of the head.

  As shown in FIG. 4, the face portion 3 includes a central portion 3a having a relatively large thickness tc and an annular shape so as to surround the central portion 3a and is larger than the thickness tc of the central portion 3a. A peripheral thin portion 3b having a small thickness tp. The durability of the face portion 3 is maintained by the central portion 3a. Further, the peripheral thin portion 3b can be greatly bent when the ball is hit. This helps to maximize the coefficient of restitution of the head, for example within the rules of golf.

  The thickness tc of the central portion 3a is preferably 2.0 mm or more, more preferably 2.3 mm or more, and further preferably 2.5 mm or more. When the thickness tc is less than 2.0 mm, the durability of the face portion 3 may be reduced. On the other hand, if the thickness tc is too large, the resilience may be lowered. Therefore, the thickness is preferably 4.0 mm or less, more preferably 3.7 mm or less, and further preferably 3.5 mm or less. From the same point of view, the thickness tp of the peripheral thin portion 3b is preferably 1.0 mm or more, more preferably 1.5 mm or more, further preferably 2.0 mm or more, and the upper limit is preferably 3.5 mm. Hereinafter, it is more preferably 3.3 mm or less, and still more preferably 3.0 mm or less.

  In addition, the face portion 3 is preferably provided with a thickness transition portion 3c that smoothly changes its thickness and connects the central portion 3a and the peripheral thin portion 3b. As a result, stress concentration at the boundary portion between the central portion 3a and the peripheral thin portion 3b is prevented, and the durability of the face portion 3 is further improved.

  The club head 1 of the present invention is provided with at least two grooves 8 that are recessed in the hollow portion i side and extend in different directions and intersect with each other in the sole portion 5.

  When a plurality of grooves extending in the same direction along the face 2 are provided on the sole portion 5 as in the prior art, distortion tends to concentrate between adjacent grooves. Further, rigidity anisotropy occurs in which the rigidity in the head longitudinal direction is significantly reduced. As a result, the durability of the sole portion 5 is deteriorated and the hitting sound tends to be reduced.

  On the other hand, in the club head 1 of the present invention, at least two grooves 8 extend in different directions and intersect each other, so that the bending rigidity and torsional rigidity of the sole portion 5 are improved in a balanced manner and in many directions. It is done. The club head 1 having such a highly rigid sole portion 5 has a high hitting sound. Specifically, it is possible to provide a desired hitting sound having a peak near 5000 to 6000 Hz.

  Further, since the grooves 8 extending in different directions can prevent excessive rigidity anisotropy from occurring in the sole portion 5, durability of the sole portion 5 is improved. Furthermore, the groove 8 provided in the sole portion 5 can absorb an impact acting on the sole portion 5 by elastic deformation that increases or decreases the groove width. Accordingly, the two grooves 8A and 8B extending in different directions can absorb vibrations of the sole portion 5 in more directions than the conventional grooves. Thereby, the impact transmitted to the golfer's hand at the time of hitting is effectively relieved, and the hit feeling is improved.

  The groove 8 of the present embodiment is composed of two grooves, a first groove 8A extending substantially linearly in the head longitudinal direction and a second groove 8B extending substantially linearly in the toe-heel direction. A mode in which these intersect (orthogonal) at one place is shown. Specifically, the two grooves 8A and 8B intersect in the middle of each length, and one groove intersection 13 is formed. In such a club head 1, the head longitudinal rigidity is enhanced by the first groove 8A, and the toe-heel direction rigidity is enhanced by the second groove 8B. Therefore, the rigidity of the sole portion 5 is improved with a good balance.

  Here, the “head longitudinal direction” means, as shown in FIG. 2, a normal N drawn from the center of gravity G of the head to the face 2 in the reference state (the intersection of the normal N and the face 2 is a sweet spot) (Referred to as SS) is defined as a direction Y parallel to the straight line projected onto the horizontal plane HP. The “toe / heel direction” is a direction perpendicular to the front-rear direction of the head.

  The crossing angle θ between the two grooves 8A and 8B is not particularly limited, but is preferably 40 degrees or more, more preferably 45 degrees or more. When the crossing angle θ is less than 40 degrees, the strain concentrates on the acute angle portion sandwiched between the grooves 8A and 8B in the sole portion 5, and there is a possibility that the durability of the sole portion is deteriorated. The upper limit of the intersection angle θ is 90 degrees.

  Here, as understood from FIG. 3, the intersection angle θ is an angle at which the center lines GL of the grooves 8A and 8B projected onto the horizontal plane HP intersect, and the smaller angle is adopted. When the center line GL is a curve, the intersection angle θ is the intersection angle of the tangent lines drawn to the respective center lines GL at the groove intersection 13. Further, the groove center line GL is a line segment passing through the middle of the opening width GW of the groove 8 as shown in FIG.

  As shown in FIG. 5, the groove 8 includes a substantially flat groove bottom 9, a groove wall portion 10 on the face side and a back face extending linearly from the groove bottom 9 in the direction of expanding the groove width. Side groove wall portion 11. In order to prevent deterioration in durability at the groove bottom 9, the thickness tg 1 of the sole portion 5 at the groove bottom 9 is preferably at least the same as the thickness tg 2 of the groove wall portions 10 and 11. . In the present embodiment, the thicknesses tg1 and tg2 of the groove 8 are formed substantially the same as the thickness ts of the other part of the sole portion 5 excluding the groove 8.

  The thicknesses tg1, tg2, and ts are not particularly limited, but are preferably 0.5 mm or more, more preferably 0.8 mm or more, and further preferably 1.0 mm or more. When the thickness ts is less than 0.5 mm, the rigidity of the sole portion 5 is excessively lowered and the durability is likely to be lowered. The upper limit of the thickness ts of the sole portion 5 may be appropriately determined depending on the balance with the head weight, but is preferably 2.0 mm or less.

  The opening width GW and the depth GD of the groove 8 are not particularly limited. However, when the opening width GW or the depth GD is too small, the reinforcing effect of the sole portion 5 by the groove 8 tends not to be sufficiently obtained. On the other hand, if the opening width GW or the depth GD is too large, stress tends to concentrate on the groove bottom 9 and the like, and as a result, damage starting from the groove 8 tends to occur. From such a viewpoint, the opening width GW is preferably 2 mm or more, more preferably 3 mm or more, and the upper limit is preferably 12 mm or less, more preferably 10 mm or less. The depth GD is preferably 0.5 mm or more, and the upper limit is preferably 5.0 mm or less.

  The opening width GW and / or the depth GD of the groove 8 may be constant or may vary. In particular, in order to alleviate the stress concentration, it is desirable that the opening width GW and / or the depth GD of the groove ends 8Ae and 8Be of the groove 8 be smoothly reduced. That is, as shown in FIG. 3, the end portions 8Ae and 8Be of the groove terminate in an arcuate curve in a plan view and do not include a sharp edge. Similarly, as shown in FIG. 4, in the cross section along the length of the groove 8, the end portion 8 </ b> Ae (not shown but the same applies to 8Be) has a smoothly reduced depth and an arc shape. The groove bottom section is formed. These serve to prevent stress concentrations that tend to occur at such edges when hitting the ends of the grooves with large balls. In the present embodiment, the end portions 8Ae and 8Be of the groove are both provided in the sole portion 5 without protruding from the sole portion. However, it is needless to say that the groove end portions 8Ae and 8Be may be provided protruding from the side portion 6.

  Further, as shown in FIG. 5, the groove wall portion 10 on the face side is inclined toward the face 2 side. The angle is represented by an inclination angle toward the face 2 with respect to the horizontal line (that is, an angle between the horizontal line and the extension line of the groove wall portion 10) θf. Further, the groove wall 11 on the back face side is inclined toward the back face BF side. This angle is represented by an angle θb toward the back face BF with respect to the horizontal line (that is, an angle between the horizontal line and the extension line of the groove wall portion 11) θb.

  The inclination angle θf or θb is preferably 30 degrees or more, more preferably 45 degrees or more. When the inclination angle is less than 30 degrees, the effect of increasing the rigidity of the sole portion 5 tends to be insufficient. The upper limit of the inclination angle θf or θb is preferably 90 degrees or less, more preferably less than 90 degrees, and still more preferably 80 degrees or less. When the inclination angle exceeds 90 degrees, a so-called dovetail shape is formed and mud and foreign matter are easily clogged in the groove 8, and the moldability is liable to deteriorate.

  Also, as shown in FIG. 6, the cross-sectional shape of the groove 8 can be variously modified. For example, in the groove 8 shown in FIG. 6A, the face-side and back-face-side groove wall portions 10 and 11 are each formed in a square groove shape having an inclination angle θf and θb of substantially 90 degrees. . Such a groove | channel 8 can raise the rigidity of the sole part 5 more effectively compared with the aspect of FIG.

  Further, the groove 8 shown in FIG. 4B is formed with a substantially triangular cross section that is sharpened toward the hollow portion i side.

  Further, the groove 8 shown in FIG. 6C is formed such that the inclination angle θb of the groove wall portion 11 on the back face side is relatively smaller than the inclination angle θf of the groove wall portion 10 on the face side. Compared to the embodiment of FIG. 6A, such a groove 8 is less likely to pierce the ground even when the sole portion 5 comes into contact with the ground during the swing, and as a result, swing-out performance is improved. Further, since the groove wall portion 10 on the face side has a relatively large inclination angle as compared with the groove wall portion 11 on the back face side, the rigidity of the groove 8 can be effectively increased as compared with the embodiment of FIG. .

  Therefore, by forming the inclination angle θb of the groove wall portion 11 on the back face side to be smaller than the inclination angle θf of the groove wall portion 10 on the face side, the durability of the sole portion 5 can be effectively enhanced while swinging performance is improved. Deterioration can be prevented. At this time, the difference in inclination angle (θf−θb) is preferably 10 degrees or more, more preferably 20 degrees or more, and the upper limit is preferably 60 degrees or less, more preferably 40 degrees or less, and still more preferably. Is preferably 30 degrees or less.

  Further, the length of the groove 8 provided in the sole portion 5 is not particularly limited, but if it is too small, the effect of improving the rigidity and the like of the sole portion 5 tends not to be sufficiently obtained. From such a point of view, the total length of the grooves obtained by adding the lengths of the grooves 8 provided in the sole portion 5 (measured along the center line GL) is preferably 30 mm or more, more preferably 40 mm or more is desirable. On the other hand, the total length of the groove 8 is preferably 100 mm or less, more preferably 90 mm or less, and still more preferably 80 mm or less, for reasons such as limitations on the dimensions of the club head and head weight.

  It is desirable that the groove intersection portion 13 where the two grooves 8A and 8B intersect is provided in the central portion of the sole portion 5. That is, a mode in which a plurality of grooves extend from the groove intersection portion 13 to the outer edge side of the sole portion 5 is desirable. This helps to increase the rigidity of the sole portion 5 in a balanced manner in many directions.

  Here, as shown in FIG. 3, the center portion of the sole portion 5 includes a maximum length SL of the sole portion 5 in the head front-rear direction and a maximum width SW of the sole portion 5 in the toe / heel direction, respectively. When equally divided, each intermediate area is defined as a rectangular area 5 </ b> C that overlaps with the sole portion 5. In addition, the sole portion 5 is an area surrounded by the edge when the side portion 6 can be clearly distinguished from the edge. However, the portion where the edge is unclear is shown in FIG. In the state, the intersecting line between the horizontal plane HP separating 10 mm from the horizontal plane HP and the head outer surface (excluding the face) is regarded as the edge, and the region of the sole portion 5 is determined.

  In the club head 1 of the present invention, the arrangement of the grooves 8 is not limited to the embodiment shown in FIGS. For example, as shown in FIG. 7, in the groove 8, the first groove 8A extending in the longitudinal direction of the head and the first groove 8A form a three-way-shaped (T-shaped) groove intersection 13. And a second groove 8B extending in the toe-heel direction. That is, the first groove 8A intersects the second groove 8B without penetrating the second groove 8B.

  In the embodiment of FIGS. 1 to 4, the length of the first groove 8A and the length of the second groove 8B are formed substantially the same. However, as in the embodiment of FIG. The length L1 of the first groove 8A may be different from the length L2 of the second groove 8B. However, if the difference between the lengths L1 and L2 of the first groove 8A and the second groove 8B is increased, the rigidity balance of the sole portion 5 may be deteriorated, so the ratio of the lengths (L1 / L2 ) Is preferably 1.0 ± 0.5, more preferably 1.0 ± 0.3, and still more preferably 1.0 ± 0.1.

  Further, as shown in FIG. 8, the groove 8 provided in the sole portion 5 can be inclined with respect to the head longitudinal direction and the toe-heel direction. For example, in the club head 1 of FIG. 8A, the first groove 8A and the second groove 8B are both inclined at an angle of ± 15 degrees with respect to the toe-heel direction. The crossing angle θ between the two grooves 8A and 8B is 30 degrees. Further, in the club head 1 in FIG. 5B, the first groove 8A and the second groove 8B are both inclined at an angle of ± 22.5 degrees with respect to the toe-heel direction. And the crossing angle θ of 8B is 45 degrees.

  Further, as shown in FIGS. 3, 7, and 8, the groove 8 has a groove 8 </ b> A and a groove 8 </ b> A with respect to the head front-rear direction line passing through the center of the groove intersection 13 (the intersection of the two center lines). It is desirable that 8B be arranged substantially line-symmetrically. Thereby, the toe part side and the heel part side of the sole part 5 are reinforced with good balance.

  Further, as shown in FIG. 9, the sole portion 5 may be provided with three or more grooves 8. In the embodiment of FIG. 9A, the first to third grooves 8A, 8B and 8C extend in three different directions and intersect to form one groove intersection 13. . In other words, a plurality of grooves extend in six directions that are substantially equiangularly spaced from one groove intersection 13. In this embodiment, the crossing angle θ of each groove 8 is 60 degrees, and each of the grooves 8A to 8C crosses at an intermediate position in the length. Such a groove arrangement can improve the rigidity of the sole portion 5 in a balanced manner in multiple directions. In such an embodiment, it is desirable that the groove 8 includes at least one groove 8A extending in the front-rear direction of the head in order to increase resistance to stress generated during hitting.

  In the embodiment of FIG. 9B, the first groove 8A extending in the front-rear direction of the head, the second groove 8B extending in parallel with a distance in the toe-heel direction, and the first and second grooves And a third groove 8C that intersects both of the grooves 8A and 8B. Therefore, in this embodiment, two groove crossing portions 13 are provided in the sole portion 5.

  Furthermore, in the embodiment of FIG. 9C, the first to third grooves 8A, 8B, and 8C are arranged in a triangular shape so as to intersect so that three groove intersecting portions 13 are formed in the sole portion 5. You can also. In this embodiment, the grooves 8A to 8C intersect at an intersection angle θ of 60 degrees, and the groove intersecting portion 13 is disposed substantially at the apex of the equilateral triangle. Such a club head 1 can also improve the rigidity of the sole part 5 in a well-balanced manner.

  Further, as shown in FIG. 10, it is desirable that a vibration absorbing material 15 made of an elastic material is disposed in at least a part of at least one groove 8. Such a vibration absorber 15 converts the vibration transmitted to the groove 8 into thermal energy and attenuates it at an early stage, thereby further improving the feel at impact. Further, the vibration absorbing material 15 arranged in the groove 8 is useful as a weight member that increases the weight of the sole portion 5 and thus realizes a low center of gravity and a large depth of center of gravity.

  The vibration absorber 15 is not particularly limited as long as it is a viscoelastic material that absorbs impact, and examples thereof include rubber, a thermoplastic resin, and a thermosetting resin. In particular, a thermoplastic resin such as polyurethane is preferable from the viewpoint of moldability. Such a vibration absorbing material attenuates vibration by converting vibration into heat energy.

In order to effectively exhibit such vibration action, the complex elastic modulus of the vibration absorber 15 is preferably 1.4 × 10 ⁷ dyn / cm ² or more, more preferably 1.0 × 10 ⁸ dyn / cm ^2. More preferably, 3.9 × 10 ⁸ dyn / cm ² or more is desirable. If the complex elastic modulus is less than 1.4 × 10 ⁷ dyn / cm ² , the vibration of the sole portion 5 is excessively absorbed, which may result in a low hitting sound. On the other hand, if the complex elastic modulus of the vibration absorbing material 15 is excessively large, vibration from the groove wall portion or the like cannot be sufficiently attenuated, and as a result, the shot feeling may not be improved. From such a viewpoint, the complex elastic modulus of the vibration absorbing material 15 is preferably 2.0 × 10 ¹⁰ dyn / cm ² or less, more preferably 1.4 × 10 ¹⁰ dyn / cm ² or less, and still more preferably 2. 7 × 10 ⁹ dyn / cm ² or less is desirable. Note that the complex elastic modulus is a viscoelastic spectrometer manufactured by Shimadzu Corporation, which is a 4 mm wide × 30 mm long × 2.0 mm thick strip-shaped sample (each holding 5 mm at both ends and the length of the displacement portion of the sample is 20 mm). Is a value measured under conditions of a temperature of 10 ° C., a frequency of 10 Hz, an initial strain of 10% (elongation of 2 mm), and an amplitude of ± 0.0625% (± 0.0125 mm).

  Such a vibration absorbing material 15 is formed in advance in a shape corresponding to the inner peripheral surface of the groove 8 and is fixed in the groove 8 using, for example, an adhesive. At this time, in order to prevent the vibration absorbing material 15 from being peeled off due to contact with the ground, it is desirable that the vibration absorbing material 15 is arranged in the groove without protruding from the groove 8 as shown in FIG. . Preferably, the vibration absorbing material 15 is disposed over the entire length of one groove 8.

  Although the embodiments of the present invention have been described above, the present invention can be modified and implemented in various embodiments. For example, as shown in FIG. 11A, it goes without saying that another groove 8E that does not intersect any groove may be provided in the sole portion 5. Further, as shown in FIG. 11B, the present invention includes a mode in which an odd number of grooves extends radially around the groove intersection 13. Further, the groove 8 is not limited to a straight one, but may be a curved one as shown in FIG.

Next, a preferred embodiment of the present invention will be described.
The heads of Examples and Comparative Examples are wood type golf club heads having a head volume of 460 cm ³ in which a face member made of a titanium alloy (Ti-6Al-4V) and a head body are joined. The face member was finished with a thickness of 2.8 mm at the center and a thickness of 2.5 mm at the peripheral thin portion by pressing a Ti-6Al-4V plate.

  Further, the head main body is a Ti-6Al-4V lost wax precision casting product, the thickness of the crown and side portions is 0.7 mm, and the thickness of the sole portion is 1.2 mm. For those having a groove in the sole part, this groove was formed by casting. Each part of the groove was 1.2 mm which is the same as the thickness of the sole part. And both members were joined by carbon dioxide laser welding.

  The vibration absorbers include silicon rubber, vulcanized rubber (SBR + carbon), polyether block amide copolymer (product number “PEBAX5533” manufactured by ARKEMA) and 11-nylon (product number “RILSAN BESN TL manufactured by ARKEMA”). 4) were used. These were all formed along the cross-sectional shape of the groove and fixed to the groove with a cyanoacrylate adhesive. Specific specifications of the grooves and the like are as shown in Table 1. The sweet spot height is a vertical height from the horizontal plane to the sweet spot in the reference state.

  Next, each head was tested for durability, feel at impact and hitting sound. The test method is as follows.

<Durability>
First, the same shaft made of FRP was attached to each test head to make a 45-inch wood type golf club. Next, each club was attached to a swing robot, and the golf ball was hit by adjusting the head speed to 54 m / s, and the number of hits in which the club head was damaged was examined. The head damage was examined with the naked eye after every 100 shots. The maximum number of hits was 5000.

<Hit feel>
Using the above-mentioned golf club, a professional and single player golfer made 12 trial shots of commercially available three-piece golf balls (XXIO (registered trademark) DC manufactured by SRI Sports Co., Ltd.) five balls at a time. Relative evaluation was performed with reference to the impact at the time of hitting.

<Hit sound>
The three-piece golf balls were hit with each golf club using a microphone and a sound level meter manufactured by Lion, and the hitting sounds were collected. A frequency response function of the hitting sound was obtained from the hitting sound using an FFT analyzer or the like (CF-4220 manufactured by Ono Sokki Co., Ltd., analysis software “Graduo”), and a peak frequency near 5000 Hz was read. Since recent golfers tend to prefer high hitting sounds, the higher the frequency, the better the hitting sound.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the club head of the example had improved durability, feel at impact, and sound at impact. In addition, about what arranged vibration absorbing material in the groove,

It is a perspective view of the club head of the regular state which shows one Embodiment of this invention. FIG. It is an enlarged bottom view of FIG. It is XX sectional drawing of FIG. FIG. 4 is a cross-sectional view taken along the line AA in FIG. (A)-(c) is sectional drawing of the groove | channel which shows other embodiment of this invention. It is a bottom view of the club head which shows other embodiment. It is a bottom view of the club head which shows other embodiment. (A)-(c) is sectional drawing of the groove | channel which shows other embodiment of this invention. It is sectional drawing of the groove | channel which shows other embodiment. (A)-(c) is a bottom view of the club head which shows other embodiment of this invention. (A)-(c) is a bottom view of the club head of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Golf club head 2 Face surface 3 Face part 4 Crown part 5 Sole part 6 Side part 8 Groove 8A 1st groove 8B 2nd groove 8C 3rd groove 15 Vibration absorber i Hollow part Y Head front-back direction (theta) Groove Intersection angle

Claims (5)

A golf club head including a face portion having a face for hitting a ball on the front surface, a sole portion connected to the lower edge of the face and forming a bottom surface of the head, and having a hollow portion therein,
A golf club head according to claim 1, wherein at least two grooves that are recessed toward the hollow portion and extend in different directions from each other are provided in the sole portion.   The golf club head according to claim 1, wherein the crossing angle of the grooves is 40 to 90 degrees.   The golf club head according to claim 1, wherein the groove includes at least three grooves extending in different directions from each other.   4. The golf club head according to claim 1, wherein a vibration absorbing material made of a viscoelastic material is disposed in at least one groove. The golf club head according to claim 4, wherein a complex elastic modulus of the vibration absorbing material is 2.0 × 10 ^{7 to} 2.0 × 10 ¹⁰ (dyn / cm ² ).

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