Metallic hollow golf club

Abstract

To set a shaft joining fulcrum at the same height as a hitting point or lower, to increase a hitting angle and to reduce a spin amount.SOLUTION: A male screw 75 is formed at the lower end portion of the outer peripheral surface 72 of the sleeve 7. A female screw 81 of a cap nut 8 is screwed into the male screw 75, and the sleeve 7 is fixed to an insertion hole composed of a large diameter circular hole 31, a step part 32 and a small diameter circular hole 33. The cap nut 8 is fastened to the lower end portion 35 of the hosel portion 3 via a washer 82.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hollow metal golf club, and more specifically to a hollow metal golf club in which the upper end of the fixing part of the golf shaft is positioned close to the impact point (face center), thereby increasing the launch angle of the golf ball and reducing the amount of spin, thereby increasing the flight distance. [Background technology]

[0002] A hollow metal golf club has been proposed in which the upper end of the attached portion of the golf shaft is positioned closer to the impact point (face center), thereby increasing the initial velocity, increasing the launch angle of the golf ball, reducing the spin rate, and enabling the golf ball to be hit farther (Patent Document 1). In this hollow metal golf club, the upper end of the golf shaft, which is attached with adhesive, is unconstrained, and the attachment point below this upper end (the upper end of the adhesive portion (shaft joint fulcrum)) is positioned closer to the impact point (face center), thereby increasing the launch angle of the golf ball, reducing the spin rate, and enabling the golf ball to be hit farther. In this case, the tip of the golf shaft 6 is inserted into a sleeve 7 and fixed with an adhesive.

[0003] On the other hand, a golf club has also been proposed in which a sleeve threaded hole 6h is formed in the lower end of a sleeve 5 to which the tip of a shaft 4 is fixed with an adhesive, and a bolt 6 is screwed into this sleeve threaded hole 6h to fix the shaft 4 to the head 2 (Patent Document 2). On the other hand, a golf club is also known in which a fixing male screw 36 is fixed to the tip of a shaft holding cylinder 32 to which the tip of a club shaft 14 is adhered, and a fixing nut 44 is screwed into this fixing male screw 36 to fix the club shaft 14 to the club head 12 (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO 2017 / 073705 A1 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-124092 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-334142 Summary of the Invention [Problem to be solved by the invention]

[0005] The shaft fixing structure of the hollow metal golf club described in Patent Document 1 can bring the shaft joint fulcrum and the impact point closer together, but structurally, it cannot bring them at the same height or lower. For this reason, the hollow metal golf club described in Patent Document 1 has limitations on increasing the ball's launch angle and reducing the amount of spin. Furthermore, the fixing structure of the shaft 4 and sleeve 5 of the golf club described in Patent Document 2 includes a sleeve screw hole 6h at the bottom end of the sleeve 5, which is a female thread that requires a certain length, and structurally, it cannot bring the shaft joint fulcrum and the impact point closer together. Furthermore, the fixing structure of the shaft 14 and shaft holding cylinder 32 of the golf club described in Patent Document 3 fixes the club shaft 14 to the club head 12 with a fixing nut 44 threaded into a fixing male screw 36. Because of the fixing male screw 36, it is not possible to bring the shaft joint fulcrum and the impact point closer together.

[0006] The present invention has been made in view of the above background to achieve the following objects. SUMMARY OF THE INVENTION An object of the present invention is to provide a hollow metal golf club that allows the shaft joint fulcrum and the impact point to be closer together. Another object of the present invention is to provide a hollow metal golf club in which the shaft joint fulcrum can be set at the same height as the impact point or lower. A further object of the present invention is to provide a hollow metal golf club that can achieve a large launch angle and a reduced amount of spin. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means. That is, the metal hollow golf club of the present invention 1 is a head body having a face surface for striking a golf ball; a hosel portion formed in the head body and having an insertion hole into which a tip end of a golf shaft is inserted and fixed; a golf shaft fixing means capable of fixing only the tip end of the golf shaft at any axial position within the insertion hole, and the golf shaft is not constrained at a position beyond the upper end of the fixing portion of the tip end of the golf shaft; The golf shaft fixing means includes a sleeve in which the tip end of the golf shaft is bonded to the inner peripheral hole with an adhesive and which is inserted into the insertion hole of the hosel portion. In a metal hollow golf club having The upper end of the fastening portion is located at a position lower than the impact point at which the player hits the golf ball.

[0008] The metal hollow golf club of invention 2 is invention 1, wherein the golf shaft is unconstrained outside the insertion hole of the hosel portion. The metal hollow golf club of Invention 3 is characterized in that, in Invention 1 or 2, it comprises a male screw formed on the outer periphery of the lower end of the sleeve, and a nut screwed onto the male screw to fix the sleeve in the insertion hole.

[0009] The metal hollow golf club of Invention 4 is Invention 3, characterized in that the nut is a cap nut with a closed screw hole. The metal hollow golf club of Invention 5 is Invention 4, characterized in that the cap nut is formed with a wrench hole for turning the cap nut. [Lie angle θ] In the metal hollow golf club of the present invention, the above-mentioned "the upper end of the fixing portion is located at a position lower than the impact point where the player hits the golf ball" refers to the position when the player hits the golf ball, and the assumed lie angle θ is the position when the design lie angle is 59° to 60° and is 51° to 54°. [Effects of the Invention]

[0010] The metal hollow golf club of the present invention allows the shaft joint fulcrum and the impact point to be closer together, which increases the launch angle and reduces the amount of spin, thereby increasing the flight distance. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a partially cutaway front view showing a head body of a hollow metal golf club according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged vertical cross-sectional view showing the vicinity of a hosel portion of the head body of FIG. [Figure 3] FIG. 3 is an exploded perspective view showing the vicinity of the hosel portion of FIG. [Figure 4] FIG. 4 is a right side view of FIG. [Figure 5] FIG. 5 is a partially cutaway front view showing a head body of a hollow metal golf club according to a second embodiment of the present invention. [Figure 6] 6 is an enlarged vertical cross-sectional view showing the vicinity of the hosel portion of the head main body of FIG. [Figure 7] FIG. 7 is an exploded perspective view showing the vicinity of the hosel portion of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment of metal hollow golf club] A first embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a partially cross-sectional front view of a head body of a hollow metal golf club according to the first embodiment of the present invention. FIG. 2 is an enlarged longitudinal cross-sectional view showing the vicinity of the hosel portion of the head body of FIG. 1. FIG. 3 is an exploded perspective view showing the vicinity of the hosel portion of FIG. 2. The head body 1 shown in FIGS. 1 to 3 is an example applied to a metal wood club. The head body 1 shown in FIG. 1 does not have a lie angle of 60 degrees as specified in the Equipment Rules, but rather has a lie angle that is assumed when a player actually hits a ball. Generally, players swing from an address position with the toe raised about 14° to 16° above the designed lie angle of the head (59° to 60°). However, players do not actually hit a golf ball in this state. In reality, when swinging, a toe-down phenomenon occurs, in which the toe is lowered by 6° to 8° due to flex of the shaft or the like.

[0013] For the above reasons, when a player hits a golf ball, the expected lie angle θ, assuming a design lie angle of 59° to 60°, is 51° to 54°. Head body 1 is formed with face surface 2 having a striking surface in front for hitting the ball, hosel portion 3 which is a shaft connection portion on the shaft side, crown portion 4 at the top, and sole portion 5 at the bottom which comes into contact with the ground, and a golf shaft 6 is inserted into and fixed to hosel portion 3. In this example, face surface 2, hosel portion 3, crown portion 4, and sole portion 5 are formed by press molding titanium or a titanium alloy, and each edge is welded to form a single unit, forming hollow head body 1.

[0014] The hosel portion 3 has an insertion hole formed therein, which is composed of, in order from the upper end, a large-diameter circular hole 31, a stepped portion 32, and a small-diameter circular hole 33. A hollow, cylindrical sleeve 7 made of metal (e.g., aluminum) is inserted into the large-diameter circular hole 31, the stepped portion 32, and the small-diameter circular hole 33. The tip end (lower end) of the golf shaft 6 is fixed to the inner peripheral hole 71 of the sleeve 7 by adhesive bonding with an adhesive such as epoxy resin. The diameter of the inner peripheral hole 71 of the sleeve 7 is formed slightly larger than the diameter of the tip end of the golf shaft 6, and adhesive penetrates into the gap between the inner peripheral hole 71 and the outer peripheral surface of the tip end of the golf shaft 6, thereby fixing the tip end of the golf shaft 6 to the sleeve 7. A flange 73 is formed at the upper end of the outer peripheral surface 72 of the sleeve 7, and the outer peripheral surface of the flange 73 is tightly fitted into the large-diameter circular hole 31. Two male splines 74 are formed on the outer peripheral surface 72 of the sleeve 7, extending downward from the lower end of the flange 73. Two male splines 74 are formed circumferentially at 180-degree intervals on the outer peripheral surface 72. The male splines 74 are formed partway along the axial length of the outer peripheral surface 72 of the sleeve 7. Two female splines 34 are formed at 180-degree intervals on the lower end side of the large diameter circular hole 31 and engage with the male splines 74 to prevent rotation of the sleeve 7. In addition, a lower end surface 741 of the male splines 74 abuts against the stepped portion 32, restricting downward movement of the sleeve 7.

[0015] A male thread 75 is formed at the lower end of the outer peripheral surface 72 of the sleeve 7. The female thread 81 of a metal cap nut 8 is threaded onto the male thread 75, and the sleeve 7 is fixed in an insertion hole consisting of the large-diameter circular hole 31, the stepped portion 32, and the small-diameter circular hole 33. The cap nut 8 is tightened to the lower end 35 of the hosel portion 3 via a metal washer 82. A wrench hole 83 is formed in the cap nut 8 for turning the cap nut 8. A wrench (not shown) that fits the wrench hole 83, which may be hexagonal, star-shaped, or flower-shaped, may be used. A screwdriver may also be used instead of a wrench. The female thread 81 of the cap nut 8 is preferably closed at the lower end, preventing dirt and dust from entering the female thread 81 and the male thread 75. A hollow, cylindrical elastomer 91 having rubber elasticity is inserted into the large-diameter circular hole 31, and the lower end surface 912 of the elastomer 91 abuts against the upper end surface 76 of the sleeve 7. Additionally, a lower end surface 922 of a hollow cylindrical ferrule 92 is assembled and abuts against an upper end surface 913 of the elastomer 91. The elastomer 91 and the ferrule 92 act as buffers that absorb the strong loads applied to the golf shaft 6 from the swing through to impact.

[0016] The diameters of the inner peripheral hole 911 of the elastomer 91 and the inner peripheral hole 921 of the ferrule 92 are slightly larger than the diameter of the tip of the golf shaft 6. Therefore, the tip of the golf shaft 6 is fixed (adhered) only along the entire axial length of the inner peripheral hole 71 of the sleeve 7, and is not fixed (adhered) within the inner peripheral hole 911 of the elastomer 91 or the inner peripheral hole 921 of the ferrule 92. In other words, the upper portion of the tip of the golf shaft 6, beyond the upper end of the fixing portion (the upper end surface 76 of the sleeve 7), is unconstrained within the insertion hole of the hosel part 3. The entire axial length of the inner peripheral hole 71 of the sleeve 7 is set to a length that ensures sufficient adhesive strength between the golf shaft 6 and the sleeve 7 to withstand impact force. In this embodiment of the present invention, the lower end 77 of the inner peripheral hole 71 of the sleeve 7 can be positioned below the lower end 35 of the hosel part 3, making it possible to position the upper end of the fixing portion of the tip of the golf shaft 6 (the upper end surface 76 of the sleeve 7) below the impact point of the golf ball.

[0017] FIG. 1 shows the angular position of the head when hitting a ball, with the head body 1 placed on a horizontal plane at a set loft angle and lie angle. In other words, this is not the angle at which the head is placed at a specified loft angle and lie angle, but the set (design) angle when actually hitting a ball. FIG. 4 is a right side view of FIG. 1. As shown in FIGS. 1 and 4, a horizontal line 22 is drawn through the impact point (face center) 21 of the face 2 when hitting a golf ball 63. Also, a point of intersection 62 between the upper end of the fixing portion of the tip of the golf shaft 6 (the upper end surface 76 of the sleeve 7) and the shaft axis 61 of the golf shaft 6 is found. The horizontal line 23 passing through this intersection point 62 is then lower than the horizontal line 22 passing through the impact point (face center) 21 (for the assumed lie angle θ at the time of hitting described above). As a result, as shown in FIG. 4, the impact loft becomes flatter (arrow A in FIG. 4) during impact, resulting in a larger launch angle (arrow B in FIG. 4). In addition, the gear effect (arrow C in Figure 4) reduces the amount of spin, increasing the flight distance. As a result, the golf ball 63 is hit with a loft angle greater than the indicated loft angle. This allows for a larger launch angle at the time of impact, which is preferable for golfers with a relatively slow head speed, as it enables the golf ball 63 to fly farther.

[0018] [Second embodiment of metal hollow golf club] A second embodiment of the present invention will now be described with reference to the drawings. FIG. 5 is a partially cross-sectional front view of a head body 100 of a hollow metal golf club according to the second embodiment of the present invention. FIG. 6 is an enlarged longitudinal cross-sectional view showing the vicinity of the hosel portion 3 of the head body 100 of FIG. 5. FIG. 7 is an exploded perspective view showing the vicinity of the hosel portion 3 of FIG. 6. The lie angle θ shown in FIG. 5 is the same as the assumed lie angle (θ) when a player actually hits the ball in the first embodiment described above. The hollow metal golf club according to the second embodiment is an example in which the heel-side shape of the crown portion 4 and the shape of the hosel portion 3 are changed so that the upper end of the fixing portion of the tip of the golf shaft 6 is located outside the head body 100. In other words, the joint boundary between the golf shaft 6 and the head is located outside the head. As shown in FIGS. 5 and 6, in the second embodiment, the axial length of the large-diameter circular hole 31 formed in the hosel portion 3 is shortened, thereby shortening the overall axial length of the insertion hole consisting of the large-diameter circular hole 31, the stepped portion 32, and the small-diameter circular hole 33.

[0019] The outer diameter of a flange 73 at the upper end of the sleeve 7, which is inserted into the large-diameter circular hole 31, the stepped portion 32, and the small-diameter circular hole 33, is larger than the inner diameter of the large-diameter circular hole 31. A lower end surface 731 of the flange 73 abuts against the upper end 36 of the hosel portion 3, restricting downward movement of the sleeve 7. Two male splines 74 are formed on the outer peripheral surface 72 of the sleeve 7, extending downward from the lower end surface 731 of the flange 73. The two male splines 74 are formed 180 degrees apart on the circumference of the outer peripheral surface 72. The male splines 74 extend partway along the axial length of the outer peripheral surface 72 of the sleeve 7. Two female splines 34 are formed 180 degrees apart along the entire axial length of the large-diameter circular hole 31, and engage with the male splines 74 to prevent the sleeve 7 from rotating. Furthermore, the lower end surface 741 of the male spline 74 abuts against the step portion 32 to restrict the downward movement of the sleeve 7.

[0020] The hollow cylindrical elastomer 91 having rubber elasticity has a short axial length, and a lower end surface 912 of the elastomer 91 abuts against the upper end surface 76 of the sleeve 7. A lower end surface 922 of a hollow cylindrical ferrule 92 abuts against an upper end surface 913 of the elastomer 91 and is assembled thereto. An upper portion of the golf shaft 6, which extends beyond the upper end of the fixing portion of the tip end thereof (the upper end surface 76 of the sleeve 7), is disposed outside the head body 1. In the second embodiment of the present invention, the lower end 77 of the inner circumferential hole 71 of the sleeve 7 can be disposed below the lower end 35 of the hosel portion 3, so that the upper end of the fixing portion of the tip end thereof (the upper end surface 76 of the sleeve 7) can be disposed closer to or below the impact point 21 of the golf ball.

[0021] [Trial test] A performance evaluation was carried out to compare the metal hollow golf club of the second embodiment with a conventional product. Table 1 shows the test results. [Table 1]

[0022] The clubs used in the test shot test in Table 1 above for the Example and Comparative Examples were identical in material, club length, loft angle, and CT, and were hollow metal golf club drivers. CT is the contact time between a pendulum-type metal ball and the club face, with the practical upper limit set by rules at 257 μs. The golf club used for the Comparative Example was a driver with the product name "EF-02D" (sold by Epon Golf Co., Ltd., head office: Niigata Prefecture, Japan). The golf club used for the Example was an "EF-02D" with the shaft tip unconstrained within the hosel insertion hole, as in the previously described embodiment. The test method was a hit test conducted by the same person. Five balls were hit for each test, and the average values ​​were used. Measurements of the flight distance, head speed (H / S), etc. in Table 1 were performed using a TrackMan® 4. The Example driver used in the test shot test was confirmed to have increased flight distance, reduced backspin, and a larger launch angle. [Explanation of symbols]

[0023] 1, 100...Head body 2...Face 21...Impact point (face center) 22…horizontal line 23…horizontal line 3...Hosel 31...Large diameter circular hole 32...Step 33...Small diameter circular hole 34...Female spline 35…Lower end 36...Top end 4...Crown part 5...Sole 6...Golf shaft 61...Shaft axis 62...intersection 63...Golf ball 7...Sleeve 71...Inner hole 72...Outer surface 73... Tsuba section 731...Lower end surface 74...Male spline 741…Lower end surface 75...Male screw 76...Upper end surface of sleeve (upper end of fixed part) 77...Lower end 8...Cap nut 81...Female thread 82...Washer 83...Wrench hole 91...Elastomer 911...Inner hole 912…Lower end surface 913…Top end surface 92...Ferrule 921...Inner hole 922…Lower end surface

Claims

1. a head body having a face surface for striking a golf ball; a hosel portion formed in the head body and having an insertion hole into which a tip end of a golf shaft is inserted and fixed; a golf shaft fixing means capable of fixing only the tip end of the golf shaft at any axial position within the insertion hole, and the golf shaft is not constrained at a position beyond the upper end of the fixing portion of the tip end of the golf shaft; The golf shaft fixing means includes a sleeve in which the tip end of the golf shaft is bonded to the inner peripheral hole with an adhesive and which is inserted into the insertion hole of the hosel portion. In a metal hollow golf club having The upper end of the fixing portion is located at a position lower than the impact point at which the player hits the golf ball. A hollow metal golf club.

2. 2. The metal hollow golf club according to claim 1, The golf shaft is unconstrained outside the insertion hole of the hosel portion. A hollow metal golf club.

3. 3. The metal hollow golf club according to claim 1, a male thread formed on the outer periphery of the lower end of the sleeve; a nut screwed onto the male thread to fix the sleeve in the insertion hole; A metal hollow golf club comprising:

4. 4. The metal hollow golf club according to claim 3, The nut is a cap nut with a closed screw hole. A hollow metal golf club.

5. 5. The metal hollow golf club according to claim 4, The cap nut has a wrench hole for turning the cap nut. A hollow metal golf club.

Images