JP2005046442A - Putter type golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the directional stability of a backswing and a stroke. <P>SOLUTION: The putter type golf club head 1 satisfies a formula (1) 0.5≤(Mx/My)≤1.0 and a formula (2) 0.2≤(My/Ms)≤0.5. Mx is the moment of inertia around a horizontal axis HL passing through the center of gravity G of the head in a reference condition in which the head is held at a specified loft angle and a lie angle, parallel with a face 2, My is the moment of inertia around a vertical axis VL in the reference condition passing through the center of gravity G of the head and Ms is the moment of inertia around the axial center line CL of a shaft fastening portion 4 to which a shaft S is fastened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a putter type golf club head capable of improving the directional stability of takeback and stroke.

  Generally, in a putter type golf club, the face surface is set at a right angle to a target line (address). Then, without changing the direction of the head, it is pulled straight back (take back), and the ball is impacted (stroke) by returning the addressed state again so that the head passes. If the takeback or stroke is not performed correctly, the face face of the head will not return correctly to the addressed state and the ball cannot be rolled onto the intended line. This reduces the accuracy of putting.

For example, Patent Documents 1 to 3 listed below are proposed as techniques for suppressing rotational blur of the head that occurs when a ball is hit with a sweet spot removed, for wood type golf club heads and iron type golf club heads. These patent documents describe limiting the value of the moment of inertia related to a specific axis of the head.
JP 2000-197716 A JP 2001-299968 A JP 2002-315852 A

  However, each of the above patent documents is a technique related to a wood type golf club head. Wood-type golf clubs are used in a high-speed region where the speed when hitting a ball (so-called head speed) is about 30 to 50 m / s, but putter-type golf clubs have a head speed as low as about 3 m / s at most. Used in the area. Based on such a difference in head speed, the putter type golf club head needs to be set differently from the wood type golf club head with respect to the moment of inertia.

  In the case of a wood-type golf club head, the orientation of the face face of the head changes greatly between address, takeback, and impact. In the case of a putter-type golf club, as described above, the face of the head is changed between address and impact. It is necessary to improve so that the orientation of the surface does not change.

  The present invention has been devised in view of the above-described problems. The moment of inertia about the vertical axis passing through the center of gravity of the head, the moment of inertia about the horizontal axis, and the axis center line of the shaft fixing portion to which the shaft is fixed. It is an object of the present invention to provide a putter-type golf club head that can stabilize the orientation of the head in takeback and stroke, and thus improve the accuracy of putting, based on the regulation of the moments of inertia in relation to each other.

The invention described in claim 1 among the present invention is a putter type golf club head satisfying the following formulas (1) and (2): 0.5 ≦ (Mx / My) ≦ 1.0 ... (1)
0.2 ≦ (My / Ms) ≦ 0.5 (2)
(Where, Mx: moment of inertia around the horizontal axis passing through the center of gravity of the head and parallel to the face surface in the reference state with the head held at the specified loft angle and lie angle, My: vertical axis in the reference state passing through the center of gravity of the head Inertia moment around, Ms: moment of inertia around the axial center line of the shaft fixing part to which the shaft is fixed).

In the invention according to claim 2, the inertia moment My is 2000 to 4000 (g · cm ² ), the inertia moment Mx is 1000 to 3000 (g · cm ² ), and the inertia moment Ms is 6000 to 13000 (g · cm ² ). ^2. The putter type golf club head according to claim 1, wherein the putter type golf club head is cm ² ).

  According to a third aspect of the present invention, in the reference state, from the toe end of the head to the heel side, the toe side of the head, and a toe side portion that is a region of 30% of the head length L that is the maximum length in the heel direction; The maximum depth in the front-rear direction of the head from the leading edge to the heel side which is 30% of the head length L from the heel end of the head to the toe side, and between the toe side and the heel side part When virtually divided into a back side portion that is a region separating a distance of 50% or more of the length W and a central portion that is a remaining region, the weight of the toe side portion and the weight of the back side portion The putter type golf club head according to claim 1 or 2, wherein the ratio is 30:70 to 60:40.

  The invention according to claim 4 is the putter type golf club head according to any one of claims 1 to 3, wherein the following expression (3) is satisfied.

  0.6 ≦ (Mx / My) <0.8 (3)

  According to the present invention, the weight distribution of the head is optimized, and the head shake in the vertical direction and the horizontal direction is suppressed during takeback and stroke, and the directional stability is improved. For this reason, the face surface can be easily returned to the address state correctly, so that the putting accuracy is improved.

  According to the second aspect of the present invention, when the inertia moments My, Mx, and Ms regarding the respective axes of the head are specifically limited, the above-described effect is further improved.

  Further, when the moment of inertia Ms around the axis center line of the shaft fixing portion is increased, the weight of the toe side portion that is generally farthest from the shaft increases. As a result, the sweet spot on the face surface tends to be largely shifted to the toe side from the face center. When the ratio of the weight of the toe side portion of the head and the weight of the back side portion is appropriately limited as in the third aspect of the invention, the sweet spot can be prevented from greatly deviating from the face center. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 is a perspective view of a putter type golf club head according to the present embodiment, FIG. 2 is a plan view thereof, FIG. 3 is a front view of FIG. 2 viewed from the face side, and FIG. 4 is a view of FIG. FIG. 5 is a side view, and FIG. 5 is a sectional view taken along line AA in FIG.

  The putter type golf club head (hereinafter, simply referred to as “head”) 1 of the present embodiment extends from the face surface 2 to the rear of the head, and the trailing edge Lb in a plan view shown in FIG. It is formed in a generally bowl-like shape in plan view with a border. This shape is sometimes called a mallet type. Further, the total weight of the head 1 is not particularly limited, but if it is too large, it becomes difficult to take back or stroke, and conversely, if it is too light, the direction of the head tends to change. From such a viewpoint, it is desirable to set it as about 320-350g.

  In the present embodiment, the head 1 is made of a metal material, and has the smooth face surface 2 that impacts the ball. The face surface 2 may be composited with resin, rubber, dissimilar metals, or the like on the surface. Further, in this embodiment, the face surface 2 is a horizontally long rectangular shape extending in the toe and heel directions of the head 1, and as shown in FIG. An inclined loft angle α is provided. The height FH (FIG. 3) of the face surface 2 is preferably about 20 to 40 mm, for example.

  Further, the head 1 is provided with a shaft fixing portion 4 to which the shaft S is fixed on the heel side. The shaft fixing portion 4 of this embodiment is formed of a bottomed hole that is recessed substantially perpendicularly to the upper surface of the head and has a substantially circular shape. The axial center line CL of the shaft fixing portion 4 substantially coincides with the axial center line of the shaft S to be inserted later (however, in the case where the shaft S is bent, it becomes the axial center line of the fixing portion of the shaft S). .

  In the head 1 of the present invention, the weight distribution is optimized in accordance with the swing motion of the putter, and the head shake during takeback and stroke is suppressed. Thereby, it becomes easy to return to the state where the face surface 2 is addressed accurately, and the putting accuracy is improved. The weight distribution of the optimized head 1 can be specified by satisfying the relational expression in which the three moments of inertia Mx, My, and Ms around a predetermined axis are related to each other. Specifically, the head 1 satisfies the following expressions (1) and (2).

0.5 ≦ (Mx / My) ≦ 1.0 (1)
0.2 ≦ (My / Ms) ≦ 0.5 (2)
Here, Mx is an inertia moment about a horizontal axis HL that passes through the center of gravity G of the head 1 and is parallel to the face surface 2 in a reference state where the head 1 is held at a specified loft angle α and lie angle with respect to the horizontal plane, and My is the head. The moment of inertia about the vertical axis VL in the reference state passing through the center of gravity G, Ms is the moment of inertia about the axis center line CL of the shaft fixing portion 4 to which the shaft is fixed, and the unit is (g · cm ² ). It is. When the above equation is compared with a conventional putter type golf club head, the conventional one is smaller than the value of Equation (1) and larger than the value of Equation (2).

  In general, in order to improve the putting accuracy, it is important to pull the head straight backward from the address state in the takeback, and to feed the head straight forward in the stroke. That is, in the putter type golf club, it is not preferable that the face surface is opened or closed in each state such as an address, a takeback and a stroke. Furthermore, in the putter type golf club, it is also important to reduce the vertical blur of the face surface in the takeback and stroke so that the loft angle α of the head 1 does not change. The golfer makes such efforts, but it is important to improve the head 1 so that it is less likely to be shaken during takeback and stroke.

  In the present invention, the ratio of the moment of inertia Mx about the horizontal axis HL and the moment of inertia My about the vertical axis VL is limited to 0.5 to 1.0, which is larger than the conventional value, by the above formula (1). . Thereby, especially in the operation of pulling the head backwards very slowly like a takeback, the left / right blur (blurring in a direction perpendicular to the target line) of the head is suppressed, and the direction of the takeback is stabilized. FIG. 6 shows a graph of the moments of inertia Mx and My, and the range of the formula (1) is indicated by hatching.

  On the other hand, when the ratio (Mx / My) is smaller than 0.5, the inertia moment Mx around the horizontal axis HL is excessively smaller than the inertia moment My around the vertical axis VL. In this case, at the time of takeback, the effect of suppressing rotational blurring in the vertical direction of the face surface 2, particularly around the horizontal axis HL is unfavorable. On the contrary, when the ratio (Mx / My) is larger than 1.0, the inertia moment Mx around the horizontal axis HL becomes excessively larger than the inertia moment My around the vertical axis VL. As a result, at the time of takeback, the effect of suppressing rotational blurring in the left-right direction, particularly around the vertical axis VL tends to be reduced. It is particularly preferable that the ratio (Mx / My) satisfies the following formula (3) or formula (4).

0.6 ≦ (Mx / My) <0.8 (3)
0.6 ≦ (Mx / My) <0.7 (4)
In the present invention, the ratio of the moment of inertia My around the vertical axis VL to the moment of inertia Ms around the axis center line CL of the shaft fixing portion 4 is limited to 0.2 to 0.5 by the equation (2). . This is useful for minimizing the blurring of the face surface 2 particularly during a stroke. During the stroke, the head speed is gradually accelerated and becomes faster than during takeback. In this case, it is the moment of inertia Ms around the axial center line of the shaft fixing portion 4 rather than around the center of gravity of the head that has a great influence on head blurring. In the expression (2), the inertia moment Ms is set to be larger than the inertia moment My to stabilize the head behavior during the stroke. The moment of inertia Ms around the shaft axis is considered to have a great influence on so-called “cutting” in which the movement is switched from takeback to stroke. Therefore, by increasing the moment of inertia Ms as shown in the equation (2), the behavior at the time of turning is stabilized, and the face surface 2 that is often used in an average golfer is excessively returned (in the case of a right-handed golfer, the face surface 2 is To the left of the target line.). FIG. 7 shows a graph of moments of inertia My and Ms, and the range of equation (2) is indicated by hatching.

  When the inertia moment ratio (My / Ms) is smaller than 0.2, the inertia moment My around the vertical axis VL is excessively larger than the inertia moment Ms around the axis center line CL of the shaft fixing portion 4. Therefore, when the ratio (My / Ms) is larger than 0.5, the moment of inertia around the axis center line CL is reduced. Since Ms is excessively smaller than the moment of inertia My around the vertical axis VL, the head is likely to be returned or generated. It is particularly preferable that the ratio (My / Ms) satisfies the following formula (5).

0.3 ≦ (My / Ms) ≦ 0.4 (5)
Further, it is particularly desirable to limit the specific values of the respective moments of inertia Mx, My, and Ms as shown by the chain lines in FIGS. For example, the moment of inertia My is preferably 2000 to 4000 (g · cm ² ), more preferably 2000 to 3000 (g · cm ² ), and particularly preferably 2100 to 2700 (g · cm ² ). The moment of inertia Mx is preferably 1000 to 3000 (g · cm ² ), more preferably 1000 to 2000 (g · cm ² ), and particularly preferably 1000 to 1500 (g · cm ² ). As a result, the left / right blur around the vertical axis VL and the vertical blur around the horizontal axis HL can be further reduced to further improve the direction stability during take-back or stroke. Further, the moment of inertia Ms is preferably 6000 to 13000 (g · cm ² ), more preferably 6000 to 9000 (g · cm ² ), and particularly preferably 6000 to 8500 (g · cm ² ).

  There is no particular limitation on the shape and material of the head as long as it satisfies the limitation of the moment of inertia as described above, but an example in which such weight distribution design can be easily performed will be described below. For example, the head 1 according to the present embodiment includes a head body 10 formed of a metal material having a small specific gravity such as aluminum or aluminum alloy, and a weight member 11 fixed to the head body 10.

  The head body 10 has a mallet shape as described above. This is advantageous in that a large head volume is secured and the degree of freedom in weight distribution design is increased. The head body 10 is provided with a through hole 3 that penetrates the head body 10 in the toe and heel directions. As shown in FIG. 4, the through hole 3 has a rectangular cross section. As a result, the head main body 10 is located in front of the through hole 3 and includes the face base 3 including the face surface 2, the upper wall portion 5 disposed above the through hole 3, and the lower portion disposed below the through hole 3. A side view having a wall portion 6 and a back wall portion 7 arranged behind the through hole 3 and connecting the upper wall portion 5 and the lower wall portion 6 is formed in an annular shape. The through hole 3 can distribute the head weight up and down, front and back, and is useful for adjusting the moments of inertia Mx and My.

  The head body 10 is provided with a weight mounting hole 9 to which the weight member 11 can be fixed. In the present embodiment, one weight mounting hole 9 is formed by an upper hole 9A provided in the upper wall part 5 and a lower hole 9B provided concentrically with the upper hole 9A in the lower wall part 6. . The upper hole 9A is a circular hole formed of one or more, more preferably a plurality (eight in this example) penetrating the upper wall portion 9 vertically. The lower hole 9B is formed with the same inner diameter as the upper hole 9A. In this example, the lower hole 9B is a bottomed concave hole. The upper and lower ends of one weight member 11 are supported by the pair of upper holes 9A and lower holes 9B, respectively, and can be fixed by caulking, adhesion welding, screws, or the like. However, the lower hole 9B can also be a through-hole, like the upper hole 9A. Furthermore, the lower hole 9B can be omitted, and the weight mounting hole 9 can be configured only by the upper hole 9A.

  In this embodiment, as shown in FIGS. 1 and 8, the weight member 11 is exemplified by a cylindrical member having an outer diameter that can be inserted into the upper hole 9A and the lower hole 9B. The weight member 11 includes a first weight member 11A formed of a single metal material, and a second weight member 11B to which at least two weight pieces 11a, 11b... Formed of different metal materials are fixed. Can be included. The second weight member 11B can easily and finely adjust the height of its center of gravity by changing the specific gravity and occupation ratio of the weight pieces 11a and 11b. Accordingly, it is possible to finely adjust the weight distribution in the vertical direction, which is particularly effective for adjusting the inertia moment Mx and the like. Of course, in the first weight member 11A, two or more kinds of different metal materials can be used.

  As the metal material constituting the weight member 11, stainless steel (specific gravity about 7.8 to 8.0), nickel-copper alloy (specific gravity about 8.9), tungsten alloy (specific gravity about 12 to 19) or copper alloy (specific gravity) About 8 to 13) is desirable. In particular, stainless steel is particularly preferable in consideration of workability, productivity, cost, and the like. Further, the weight member 11 need not be mounted in all the weight mounting holes 9. As described above, it is particularly desirable in that the weight distribution of the head 1 can be easily performed by forming a plurality of weight attachment holes 9 in the head 1 in advance and attaching the weight members 11 to only necessary portions.

  Further, as shown schematically in plan view of the reference state in FIG. 9, the head 1 is the toe of the head 1 from the toe end T that forms the most toe side to the heel side, and the head length that is the maximum length in the heel direction. A toe side A that is 30% of L, a heel side B that is 30% of the head length L from the heel end H of the head 1 to the toe side, the toe side A and the heel Back side portion C that is a region that is separated by 50% or more of the maximum depth length W in the front-rear direction of the head 1 from the leading edge LE and the central portion D that is the remaining region. When virtually divided, it is desirable that the ratio of the weight of the toe side A and the weight of the back side C is 30:70 to 60:40, more preferably 40:60 to 60:40.

  In general, in order to increase the moment of inertia Ms around the axis center line CL of the shaft fixing portion 4, more weight is distributed to a position farthest from the axis center line CL, specifically, the toe side portion A. It is necessary to increase the weight. In this case, the sweet spot SS of the face surface 2 (the point where the normal line drawn from the head center of gravity G to the face surface 2 intersects the face surface 2 as shown in FIG. 4) is a diagram of the face surface 2 shown in FIG. There is a tendency to shift to the toe side more than the core face center FC. Since a general golfer usually cannot know the position of the sweet spot SS, he tries to hit the ball at the face center FC. In this case, if the difference between the sweet spot SS and the face center FC is large, there is a problem that a miss hit is caused and a side spin is applied to the hit ball or the hit feeling is impaired.

  In this embodiment, by appropriately limiting the ratio of the weight of the toe side portion A of the head 1 and the weight of the back side portion C as described above, the sweet spot SS can be faced while increasing the moment of inertia Ms. It is possible to prevent a large deviation from the center FC toward the toe. Therefore, the toe and heel direction deviation between the actual hit point (face center FC) and the sweet spot SS is substantially matched to 5 mm or less, more preferably 3 mm or less, thereby preventing mis-hits and improving the directionality of the hit ball. Can improve. Also, the impact force acting on the golfer's hand is reduced, and the hitting feeling is excellent.

  If the head length L is too small, it is difficult to align the face surface 2 with the target line at the time of addressing. On the other hand, if the head length L is too large, the head 1 tends to blur during takeback. The head length L is preferably 60 to 110 mm. Also, if the maximum depth W of the head 1 is too small, the head lacks stability at the time of addressing, and it is difficult to obtain stability in the vertical direction. It is easy to lower. From such a viewpoint, the maximum depth length W is preferably 40 to 100 mm.

  As for the position of the shaft fixing portion 4, a general position, that is, the position of the heel side portion B described above is desirable, and in particular, it is set within a range from the leading edge LE to 50% of the maximum depth length W. desirable. The head 1 of the present invention has a feature of weight distribution, and its specific shape is not restricted to the above embodiment.

  A putter-type golf club head having the basic configuration shown in FIG. 1 was prototyped based on the specifications shown in Table 1, and a putter-type golf club having a total length of 34.5 inches was manufactured by fixing a steel shaft thereto. The test club was then used to measure the face opening angle when hitting the ball and to perform a sensory test. The specifications of the head are as shown in FIGS. The test contents are as follows.

<Face opening angle>
The tester puts on each club under test, and with a high-speed camera, the opening angle θ2 at a position 20 cm before impacting the ball at the time of the stroke and the opening angle θ1 at the moment of impact are respectively photographed. The difference δ (= θ2−θ1) was measured. The smaller the value, the better the change in the orientation of the face. The testers were performed on 12 average golfers with handicap 0-20, and each golfer was hit with 20 balls, and the average value excluding the maximum and minimum values was evaluated.

<Sensory test>
In the above test, the stability of takeback and stroke was evaluated based on the following criteria based on the sensation of each tester.

◎: 8 or more testers felt stable ○: 5-7 testers felt stable ×: 5-10 testers felt unstable Results are shown in Table 1.

テストの結果、実施例のものは、フェース開き角が小さいことが確認しうる。また官能テストにおいてもテイクバック及びストロークが安定せいていることが確認できる。

As a result of the test, it can be confirmed that the embodiment has a small face opening angle. It can also be confirmed that the takeback and stroke are stable in the sensory test.

1 is a perspective view of a putter type golf club head showing an embodiment of the present invention. FIG. FIG. 3 is a front view of FIG. 2 viewed from the face side. It is the side view which looked at FIG. 2 from the heel side. It is AA sectional drawing of FIG. It is a graph which shows the relationship between the inertia moment Mx and the inertia moment My. It is a graph which shows the relationship between the inertia moment Ms and the inertia moment My. FIG. 2 is an exploded view of FIG. 1. It is the top view which divided the head virtually. 1 is a plan view showing Example 1. FIG. 6 is a plan view showing Example 2. FIG. 6 is a plan view showing a comparative example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Putter type golf club head 2 Face surface 9 Weight attachment hole 10 Head main body 11 Weight member A Toe side part C Back part CL Shaft fixing part

Claims (4)

Putter-type golf club head satisfying the following formulas (1) and (2) 0.5 ≦ (Mx / My) ≦ 1.0 (1)
0.2 ≦ (My / Ms) ≦ 0.5 (2)
(Where, Mx: moment of inertia around the horizontal axis passing through the center of gravity of the head and parallel to the face surface in the reference state with the head held at the specified loft angle and lie angle, My: vertical axis in the reference state passing through the center of gravity of the head Inertia moment around, Ms: moment of inertia around the axial center line of the shaft fixing part to which the shaft is fixed). The inertia moment My is 2000 to 4000 (g · cm ² ), the inertia moment Mx is 1000 to 3000 (g · cm ² ), and the inertia moment Ms is 6000 to 13000 (g · cm ² ). The putter type golf club head according to claim 1. In the reference state, from the toe end of the head to the heel side, the toe side of the head, a toe side portion that is a region of 30% of the head length L that is the maximum length in the heel direction;
A heel side portion that is a region of 30% of the head length L from the heel end of the head to the toe side;
A back side portion that is a region separating the distance between the toe side portion and the heel side portion by 50% or more of the maximum depth length W in the front-rear direction of the head from the leading edge;
The ratio of the weight of the toe side portion to the weight of the back side portion is 30:70 to 60:40 when virtually divided into a central portion that is a remaining region. Or the putter-type golf club head described in 2; The putter type golf club head according to any one of claims 1 to 3, wherein the following formula (3) is satisfied.
0.6 ≦ (Mx / My) <0.8 (3)

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