JP2008279249A - Iron golf club - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an iron golf club which can raise gear effect and accelerate backspin velocity. <P>SOLUTION: A lower grounding part side of a head 1 comprising a face part 2 with a ball hitting face, a sole part 6 with a grounding face at the lower part, a top part 4, and a hosel part 3 is configured into low rigidity by forming a cavity, changing materials, etc. A weight matter 55 is placed on the gravity center of the head 50 to make moment of inertia small at the upper and lower parts of the head 50. When the length of the hosel part 3 is equal to or longer than 50 mm, the value of moment of inertia is set to be lower than 800 g cm<SP>2</SP>, and when the length of the hosel part 3 is shorter than 50 mm, the value of the moment of inertial is set to be lower than 750 g cm<SP>2</SP>. By the above described constitution, a golf club which can raise gear effect and accelerate backspin velocity is materialized. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an iron golf club with an enhanced gear effect. More specifically, the present invention relates to an iron golf club in which the lower part of the head has a low rigidity, the head has a low moment of inertia, the gear effect is enhanced, and the spin of the ball is accelerated.

  2. Description of the Related Art Conventionally, golf clubs have been variously improved so that stable hitting can be performed in order to extend the flight distance or to fly the ball to an accurate position. In particular, for example, pitching wedges and sand wedges are used in iron-type golf clubs. This iron-type golf club basically has a structure in which the inclination angle of the face surface is determined and a sole surface is provided below the face surface which is a ball hitting surface. Golf club.

  Iron golf clubs have been proposed in various structures, and are selected and used according to the player's preference, such as a flat back type, a cavity type, a pocket cavity type, and a hollow structure type. In all of these, a score line is formed on the face surface, and the backspin amount of the ball is stabilized. In a shot hitting method for placing a ball on a green, a hitting method is performed in which a backspin (reverse rotation) is applied to the ball, and the ball is launched high and stopped on a target green at a predetermined position.

  With regard to the conventional technology for increasing the gear effect for applying more backspin to this ball, the present applicant also determines the height distance from the horizontal plane where the sole surface of the head is in contact to the center of gravity of the head to the radius of the ball. A golf club having a structure that is formed larger and easily applied with a spin has been proposed (see Patent Document 1). Further, the present applicant has proposed a golf club having a configuration in which the deflection of the face at the time of hitting or the relative displacement of the face with respect to the head is increased to make it easier to spin the ball (see Patent Document 2). Furthermore, as an example of a technique for improving the score line, there is known an iron golf club that sharply forms the edge of a score line and gives a back spin to the ball (see, for example, Patent Document 3).

  Generally, a golf club that spins a ball has a score line formed on the face surface as described above. When the ball is hit, the ball relatively moves while rotating along the face surface. At that time, the ball is caught by the edge of the score line, and a stable spin is applied to the ball. In order to apply more spin, various improvements have been proposed for the face surface on which an effective score line is formed.

Recently, however, a groove profile (marking) rule has been studied internationally and a rule has been proposed in order to set a certain limit in the groove formation of the score line. That is, as a new regulation proposal for club face marking and spin generation, the first point is the value obtained by dividing the total cross-sectional area of the score line groove by the groove pitch (groove width + interval) is 0.0025 square inches / inch. It is limited to (0.0635 mm ² / mm). Second, the sharpness of the groove edge (corner) is limited to an effective minimum radius of 0.010 inch (0.254 mm).

  There have been some restrictions on the scoreline from the past, but this time the regulations will be strengthened. Therefore, it will be constrained in the future to improve the spin effect by changing the score line groove, for example, by making the angle of the groove edge sharper.

JP 2006-149478 A JP 2007-44445 A JP 2004-141277 A

  As described above, the improvement plan for providing the score line on the face surface of the golf club will be limited in the future, and it is substantially difficult to improve the edge of the groove. Therefore, there is a situation where other methods must be considered. Increasing the gear effect for applying more backspin to the ball enhances the performance of the golf club, not just the face surface. However, even if there are restrictions on the score line and its improvement is restricted, there is room for improvement in aspects other than the score line, which is required.

  The present invention has been developed to solve the above-described problems of the conventional technical background, and achieves the following object. An object of the present invention is to provide a golf club in which a gear effect is enhanced in an iron golf club so as to make it easier to apply a spin.

The present invention adopts the following means in order to achieve the object.
The iron golf club according to the first aspect of the present invention is a head including a sole portion having a ground contact surface at a lower portion, a top portion at an upper portion, a face portion having a ball striking surface for hitting a ball, and a hosel portion which is a shaft connecting portion at one end. And an iron golf club comprising a shaft having one end connected to the hosel part, wherein the grounding surface side of the head is configured with low rigidity.

The iron golf club of the present invention 2 is characterized in that, in the present invention 1, the top portion side of the head is configured with relatively high rigidity compared to the ground contact surface side.
The iron golf club of the present invention 3 is characterized in that, in the present invention 1, the grounding surface side of the head has a relatively higher coefficient of restitution than the top portion side of the head.

  The iron golf club of the present invention 4 is characterized in that, in the present inventions 1 to 3, the grounding surface side of the head is in a range on the sole portion side from a substantially horizontal plane passing through the center of gravity parallel to the score line.

The iron golf club of the present invention 5 is a head comprising a sole portion having a ground contact surface at the lower portion, a top portion at the upper portion, a face portion having a ball striking surface for hitting a ball, and a hosel portion which is a shaft connecting portion at one end. And an iron golf club comprising a shaft having one end connected to the hosel part, and when the hosel part has a length of 50 mm or more, the axis centering on the axis passing through the center of gravity of the head horizontally in the toe heel direction. The value of the moment of inertia is less than 800 g · cm ² . Preferably it is 770 g · cm ² or less.

The iron golf club of the present invention 6 is a head comprising a sole portion having a ground contact surface at the lower portion, a top portion at the upper portion, a face portion having a ball striking surface for hitting a ball, and a hosel portion which is a shaft connecting portion at one end. And an iron golf club comprising a shaft having one end connected to the shaft connecting portion, when the hosel portion has a length of less than 50 mm, the axis that passes through the center of gravity of the head horizontally in the toe heel direction is the center The value of the moment of inertia is less than 750 g · cm ² .

The iron golf club of the present invention 7 is characterized in that, in the present inventions 1 to 5, the material constituting the main part of the head has a specific gravity of 6.5 g / cm ³ or more.
The iron golf club of the present invention 8 is characterized in that, in the present inventions 1 to 6, the head is a short iron head or a wedge head.

In any case, if the rigidity of the lower part of the head is reduced and the moment of inertia of the head is reduced, the gear effect is increased and the spin is easily applied. In order to achieve this, the following means are effective.
1stly, a head is a thing of the means which comprises the hollow body which has a cavity inside only on the ground-contact side.
Secondly, the head constitutes a hollow body having a cavity therein, and only the sole portion is made of a material having a lower Young's modulus than the other portions.

Third, the head constitutes a hollow body having a cavity inside only on the grounding surface side, and a material having a high mechanical strength is laminated between the face portion and other portions at the upper portion of the cavity. Means.
Fourth, the head constitutes a hollow body having a hollow inside, and only a sole portion is a means in which a concave groove having a partially thinner thickness than other portions is formed.

Fifth, the head constitutes a hollow body having a cavity inside, and is a means for forming a thicker thickness at the upper part of the face part than at the lower part.
Sixth, the head constitutes a hollow body having a cavity inside, and is a means in which a thin concave groove is partially formed in the lower portion of the face portion.

Seventh, the head comprises a hollow body having a hollow inside, and has a face part made of the same material and a lower part of the face part made of a material having a lower hardness than that of the upper part.
Eighth, the head comprises a hollow body having a cavity inside, and the upper part and the lower part of the face part are made of different materials, and the lower part material has a lower hardness than the upper part. It is.

Ninth, the head comprises a hollow body having a hollow inside, the portion except the face portion is made of the same material, and the material of the lower part of the head is formed with a lower hardness than the material of the upper part. is there.
Tenth, the head constitutes a hollow body having a hollow inside, and the upper and lower portions of the portion excluding the face portion are made of different materials, and the lower material has a softer hardness than the upper material. Of the means formed in the material.

Eleventh, the head constitutes a hollow body having a cavity therein, and the material of the lower portion of the face portion is formed with a relatively lower Young's modulus than the material of the upper portion.
Twelfth, the head constitutes a hollow body having a cavity therein, and the material in the lower part of the portion excluding the face part is formed with a relatively lower Young's modulus than the material in the upper part.

13thly, a head is a thing of the means in which the through-groove parallel to the score line formed in the hitting surface of a face part was formed in the head intermediate part of the face part back side.
14thly, the head is of a means in which a pocket-like concave groove which is parallel to the score line formed on the hitting surface of the face part and whose toe side end part is opened is formed in the head intermediate part on the back side of the face part. It is.

Fifteenth, the head is a means in which a concave groove is formed in the lower part of the head along the vertical direction of the ground contact surface to the middle position.
Sixteenth, the head is a means in which an elastic member is disposed in a concave groove formed in the lower part of the head along the vertical direction of the ground contact surface up to an intermediate position.

Seventeenth, the head is a means in which a heavy object for reducing the vertical moment of inertia is arranged near the center of gravity of the head.
Eighteenth, the head is a means in which the vicinity of the center of gravity of the head on which a heavy object for reducing the vertical moment of inertia is arranged is formed in a concave groove.

Nineteenth, the head constitutes a hollow body having a cavity inside, and a heavy object for reducing the vertical moment of inertia is arranged in the vicinity of the center of gravity of the head. It is formed in the intermediate part.
20th, the head comprises a hollow body having a cavity inside, and a heavy object for reducing the vertical moment of inertia is arranged in the vicinity of the center of gravity of the head, and the cavity is an intermediate part above and below the face part. Is formed.

21stly, in the head, a heavy object for reducing the vertical moment of inertia is arranged in the vicinity of the center of gravity of the head, and a concave groove is formed in the middle part of the upper and lower parts. It is formed in a hollow body that is a cavity inside the part side.
Twenty-second, in the head, a heavy object for reducing the vertical moment of inertia is arranged in the vicinity of the center of gravity of the head, and this heavy object is arranged at the rising end of the lower part of the head excluding the face part. It is a thing.

  As described above in detail, the iron golf club of the present invention has a configuration in which the head is easily bent at the lower portion of the face or a configuration in which the moment of inertia is reduced, that is, the lower portion of the head is deformed to rotate. By adopting an easy-to-use structure, the face surface can be turned downward in a hitting direction, and the ball retention (contact) can be lengthened, so that the gear effect is higher than that of the prior art. Therefore, the ball is effectively rotated in the reverse direction. For this reason, the iron golf club of the present invention can apply more backspin to the ball.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The golf club that is the subject of the present invention is an iron golf club. FIG. 1 is an overall view showing the appearance of the entire iron golf club. 2 and 3 are explanatory views of the side, and FIG. 2 shows a state immediately before the ball is hit by the head. FIG. 3 shows a state immediately after the ball is hit by the head. The basic structure of the iron golf club is well known and will not be described in detail. However, in order to facilitate understanding of the present invention, an outline will be described below.

  As shown in FIG. 1, the iron golf club according to the present invention is in contact with the face portion 2 on the front surface, the hosel portion 3 that is the shaft connecting portion on the shaft side, the top portion 4 on the upper portion, the toe portion 5 on the front portion, and the ground. The head 1 is formed with a sole portion 6 at the lower portion, and a shaft 7 connected to the hosel portion 3 of the head 1. Further, the inclination angle of the hitting surface with respect to the perpendicular (vertical line) of the ground surface 11 of the sole portion 6 is defined as the loft angle δ (see FIG. 2).

  A score line 8 is inscribed on the hitting surface of the face portion 2. The invention of the golf club in which the height from the ground level 11 of the sole portion 6 to the position of the center of gravity 9 of the head is larger than the radius of the ball 10 is proposed by the same applicant as the present invention. Therefore, the spin effect will be described as an example. As shown in FIGS. 2 and 3, the head 1 swings down with respect to the ball 10 while drawing an arc so as to enter below the ball 10 when hit.

  At this time, the hitting surface of the face portion 2 hits the ball 10 in contact with the ball 10 so as to enter the lower side. As a result, the ball 10 is slightly depressed by the collision and is caught on the edge portion of the score line 8, and the ball 10 rotates counterclockwise as shown by an arrow A in FIG. In accordance with the hitting swing, the ball 10 is moved in the direction indicated by the arrow C while moving and rotating in the direction indicated by the arrow B in the drawing by relative motion on the hitting surface.

  When the ball 10 collides with the head 1 at the time of hitting, the height D of the center of gravity 9 of the head 1 is above the center of the ball 10, so that the hitting surface is instantaneously pulled down on the sole portion 6 side and the hitting surface rises. Rotate clockwise. That is, the loft angle δ instantaneously decreases (see FIG. 3). As a result, a gear effect that the ball 10 is rotated in the direction opposite to the rotation of the hitting surface is generated, and the backspin is generated. Is accelerated. Further, although not shown in other inventions, the applicant of the present invention has also proposed to increase the spin effect by other methods (see Patent Document 2).

  That is, a displacement portion is provided in which the deflection of the face portion at the time of impact or the relative displacement of the face portion with respect to the head increases. Specifically, a continuous peripheral groove is provided on the front and back of the face part, and a front-side displacement groove is provided only on the top side edge, the toe side edge, and the leading edge of the face part. At the time of hitting, relative displacement is caused so that the toe side becomes larger with the heel side as the center of rotation, thereby facilitating the ball launch by the gear effect.

  Although these techniques are effective as they are, improvements such as changing the performance of the score line 8 with respect to the hitting surface of the face portion 2 as described above are limited by new rules. Therefore, an optimum method must be found by improving the portion other than the surface of the face portion 2. The ball 10 normally collides with the lower portion of the face against the face portion 2. As described above, the ball 10 that has collided moves while relatively touching the ball striking surface on which the score line 8 is located, and the ball 10 rotates counterclockwise and backspin is applied.

  According to the present invention, when the ball 10 collides with the lower part of the face, the structure of the lower part of the head is changed so that the lower part warps backward and the fluctuation is relatively easy. That is, as described above, in the present embodiment, in order to enhance the gear effect, the hitting ball portion at the lower part of the face rotates relatively rearward with the position of the center of gravity 9 of the head 1 as a fulcrum, particularly when hitting. The head 1 can be warped.

  By doing so, the ball 10 does not move immediately after the collision, and the lower part of the face relatively pivots backward, that is, the lower part of the face is likely to be warped, so that the ball 10 stays long (contacts) on the hitting surface. ). As a result, the movement of the ball 10 on the ball striking surface becomes longer, that is, the contact time becomes longer, the bite of the ball 10 is promoted, the gear effect is increased, and the ball 10 having a large back spin is launched. As described above, the present invention solves the above-described problems and further enhances the gear effect to accelerate the spin. Next, the embodiment will be specifically described.

(Embodiment with low rigidity at the bottom of the head)
This is an example in which the lower part of the head has a low rigidity, that is, a structure that is easily bent or easily deformed, and a relative rotation is given to the head at the time of hitting to increase the gear effect on the ball and accelerate the backspin. . The iron head shown in FIG. 4 is a hollow body having a cavity 20 inside only at the lower part of the head 1, that is, only on the grounding surface side of the sole part. The cavity 20 is a space on the grounding surface side surrounded by the back surface of the face portion 21 and the portion 22 except the face portion 21.

  This is an example in which the upper part is solid and the lower part is hollowed so that the rigidity is relatively different between the upper and lower sides, and the lower part is made low in rigidity to facilitate bending. The rigidity in the present invention is based on the following definition. When a load P acts on a part of the solid, and the deformation amount generated at the load point is u, the deformation amount u is proportional to the load P in the elastic body. That is, u = αP. This proportional constant α is called softness, and 1 / α = K is called rigidity.

  In the iron head shown in FIG. 5, the head 1 is made into a hollow body having a cavity 23 therein, and the material of the lower portion of the head 1, that is, the sole portion side of the portion 24 excluding the face portion 21 on the grounding surface side, is low Young's. This is an example in which the rate material is 25. This example is also an example in which the ground surface side is lower in rigidity than the upper part and is easily bent. The iron head shown in FIG. 6 is a hollow body having a cavity 20 inside only the lower portion of the head 1, that is, the grounding surface side, and between the face portion 21 at the top of the head and the portion 26 except the face portion 21. This is an example in which the high-strength material 27 is disposed in a sandwiched manner. This example is also an example in which the rigidity is relatively different between the upper part and the lower part of the head 1 so that the grounding surface side is lower in rigidity than the upper part and is easily bent.

  In the iron head shown in FIG. 7, the head 1 is formed into a hollow body having a cavity 23 therein, and a concave groove 29 is formed in the cavity 23 at a part on the grounding surface side of the portion 28 except the face 21 at the lower part of the head. Is an example. This example is an example in which the ground contact surface side of the head 1 is made lower in rigidity than the upper portion by the concave groove 29 so as to be easily bent.

  The iron head shown in FIG. 8 is an example in which the head 1 is formed as a hollow body having a cavity 23 therein, and a step is provided in the thickness of the face portion 30. In other words, the face hitting surface of the face part 30 is the same plane, and a step is provided in the cavity 23 so that the upper part has a thick part 31 and the lower part has a thin part 32. As a result, the lower part of the face part 30 has a lower rigidity than the upper part, and the lower part of the head is easily bent.

  The iron head shown in FIG. 9 is an example in which the head 1 is formed as a hollow body having a cavity 23 inside, and a concave groove 34 is provided below the face portion 33. That is, the face hitting surface of the face portion 33 is the same plane, and a face configuration is provided in which a concave groove 34 is provided on a part of the grounding surface side on the back surface side. This is an example in which the lower portion of the face portion 33 is made lower in rigidity than the upper portion so that the lower portion of the head is easily bent.

  The iron head shown in FIG. 10 is an example in which the hardness is changed between the upper part and the lower part of the face part 35 after the head 1 has a hollow body having a cavity 23 inside. That is, the face portion 35 is made of the same material, with the upper portion made of a high hardness material 35a and the lower portion made of a low hardness material 35b. According to the hardness difference between the high hardness material 35a and the low hardness material 35, the upper portion and the lower portion of the face portion 35 are relatively different in rigidity. As a result, the lower portion of the face portion 35 is lower in rigidity than the upper portion, and the lower portion of the head is easily bent.

  The iron head shown in FIG. 11 is an example in which the hardness of the material is changed between the upper part and the lower part of the face part 36 after the head 1 is made into a hollow body having a cavity 23 inside. That is, the upper portion of the face portion 36 is made of a high hardness material 36a, the lower portion is made of a low hardness material 36b, and materials having different hardnesses are joined by welding. The rigidity of the upper part and the lower part of the face part 36 is relatively different depending on the hardness difference between the high hardness material 36a and the low hardness material 36b. As a result, the lower portion of the face portion 36 is lower in rigidity than the upper portion, and the lower portion of the head is easily bent.

  The iron head shown in FIG. 12 is an example in which the hardness of the head 1 is changed between the upper part and the lower part of the part 37 excluding the face part 21 after making the head 1 into a hollow body having a cavity 23 inside. That is, the portion 37 excluding the face portion 21 is made of the same material, with the upper portion made of a high hardness material 37a and the lower portion made of a low hardness material 37b. Due to the difference in hardness between the high hardness material 37a and the low hardness material 37b, the upper portion and the lower portion of the portion 37 excluding the face portion 21 are relatively different in rigidity. As a result, the lower portion of the portion 37 excluding the face portion 21 is lower in rigidity than the upper portion so that the lower portion of the head is easily bent.

  The iron head shown in FIG. 13 is an example in which the head 1 is formed as a hollow body having a cavity 23 therein, and the hardness is changed between the upper part and the lower part of the part 38 except the face part 21. That is, the upper portion of the portion 38 excluding the face portion 21 is made of a high hardness material 38a, the lower portion is made of a low hardness material 38b, and both materials having different hardnesses are joined by welding. Due to the difference in hardness between the high hardness material 38a and the low hardness material 38b, the upper portion and the lower portion of the portion 38 except for the face portion 21 are relatively different in rigidity. As a result, the lower portion of the portion 38 excluding the face portion 21 is lower in rigidity than the upper portion so that the lower portion of the head is easily bent.

  The iron head shown in FIG. 14 is an example in which the head 1 is changed to a different Young's modulus between the upper part and the lower part of the face part 39 after making the head 1 into a hollow body having a cavity 23 inside. That is, the upper portion of the face portion 39 is made of a high Young's modulus material 39a, the lower portion is made of a low Young's modulus material 39b, and both materials having different Young's modulus are joined by welding. The rigidity of the upper portion and the lower portion of the face portion 39 is relatively different depending on the difference in Young's modulus between the high Young's modulus material 39a and the low Young's modulus material 39b. As a result, the lower portion of the face portion 39 is lower in rigidity than the upper portion, and the lower portion of the head is easily bent.

  The iron head shown in FIG. 15 is an example in which the Young's modulus is changed between the upper portion and the lower portion of the portion 40 excluding the face portion 21 after the head 1 has a hollow body having a cavity 23 therein. That is, the upper part of the part 40 excluding the face part 21 is made of a high Young's modulus material 40a, the lower part is made of a low Young's modulus material 40b, and both materials having different Young's moduli are joined by welding. Due to the difference in Young's modulus between the high Young's modulus material 40a and the low Young's modulus material 40b, the upper portion and the lower portion of the portion 40 excluding the face portion 21 are relatively different in rigidity. As a result, the lower portion of the portion 40 excluding the face portion 21 is lower in rigidity than the upper portion, and the lower portion of the head is easily bent. In addition to the above, other methods such as heat treatment can be selected as means for making the hardness and Young's modulus different.

  The iron head shown in FIG. 16 is an example in which through grooves 42 provided on the back surface of the head 41 and parallel to the score line formed on the hitting surface of the face portion are formed in the head intermediate portion on the back surface of the face portion. FIG. 17 is a side view of FIG. The through-groove 42 is a through-groove groove that penetrates in the direction of the head 41 toward the toe part 5 and the hosel part 3. The head 41 has a configuration in which the intermediate portion formed by the through-groove 42 is lower in rigidity than the upper and lower portions of the head 41, so that the lower portion of the head 41 is easily bent when hit. As a result, the lower portion of the head 41 is low in rigidity and easily bent.

  The iron head shown in FIG. 18 is provided on the back surface of the head 43. A pocket-shaped concave groove 44 that is parallel to the score line formed on the hitting surface of the face portion and has an open toe side end portion is provided on the back surface of the face portion. 43 is an example formed in the middle part. FIG. 19 is a side view of FIG. In this iron head, since the side end portion of the toe portion 5 of the pocket-shaped groove 44 is open, the portion of the pocket-shaped groove 44 has low rigidity, so that the lower portion of the head 43 is easily bent at the time of hitting. It has a configuration. As a result, the lower portion of the head 43 is low in rigidity and easily bent.

  In the iron head shown in FIG. 20, a groove 46 is formed in the lower part of the head 45 up to an intermediate position in a substantially vertical (vertical) direction from the ground plane, more precisely in a direction from the vertical to an acute angle (almost loft angle). This is an example of the configuration. In the example in which a groove 46 is provided in a slit shape in the portion 47 excluding the face portion which is almost integrated with the back surface of the face portion, the thickness of the lower portion of the face portion is relatively smaller than the thickness of the upper portion of the face portion. It is getting thinner. With this configuration, the lower portion of the head is easily bent when hit. As a result, the lower part of the head has low rigidity and is easily bent.

  The iron head shown in FIG. 21 has a configuration in which a concave groove 46 is formed from the bottom surface of the sole portion to the middle position along the loft angle direction of the ground contact surface with respect to the lower portion of the head 45 in the same manner as in FIG. However, in this example, an elastic body 48 such as rubber or synthetic resin is disposed in the concave groove 46. Also in this example, the lower part of the head is easily bent at the time of impact, and as a result, the lower part of the head becomes low in rigidity and easily bent.

(Embodiment with reduced moment of inertia)
Reduced the moment of inertia of the head in the vertical direction to make it easier to return the head at the time of hitting, giving a relative rotation to the head at the time of hitting, increasing the gear effect on the ball and accelerating backspin This is an example. The iron head shown in FIG. 22 is an explanatory view showing an example of a head in which the vertical moment of inertia is reduced. As an example of comparison, FIG. 23 shows a head of an iron golf club in the configuration of the prior art.

22 and FIG. 23 assume that the center of gravity of the head is the same, and the difference will be explained. In the case of the conventional iron head shown in FIG. 23, the resistance force for the relative rotation of the head 51 becomes large. ing. This indicates a state in which the head 51 is difficult to rotate, and the moment of inertia in the vertical direction around the position of the center of gravity exceeds 850 g · cm ² .

  On the other hand, in the case of the iron head shown in FIG. 22, by changing the configuration of the head 50 without changing the face surface of the head 50, the resistance force for the relative rotation of the head 50 is reduced, and the rotation of the head 50 is performed. It was easy to do. The magnitudes of the moments of inertia of the iron head shown in FIG. 23 are indicated by the rotation arrows a and b. The iron head shown in FIG. 24 shows a state immediately before the ball 53 collides with the face portion 52 of the head 50. When the ball 53 collides with the head 50, the iron head changes as shown in FIG. The ball 53 is given a spin and rotates counterclockwise as indicated by an arrow, and relatively moves on the hitting surface of the face portion 52.

Further, the position of the head 50 immediately before the collision changes from the state indicated by the dotted line 50a to the solid line position shown in the figure. In this state, an inertia moment is generated in the vertical direction with respect to the head 50, and the head 50 rotates relative to the position of the center of gravity 54. The inertia moment of the head 50 is small, and the rotational deformation is larger than that shown in FIG. As a result, in the case of the iron head shown in FIG. 22, the vertical moment of inertia achieved less than 800 g · cm ² at a length of the hosel part (this definition will be described later) at 50 mm or more.

As described above, the iron golf club according to the present invention includes the sole portion 6 having the ground contact surface at the lower portion, the top portion 4 at the upper portion, the face portion 2 having a ball striking surface for hitting the ball, and the shaft connecting portion at one end. The head 1 is composed of a hosel portion 3, and a shaft 7 having one end connected to the hosel portion 3. When the length of the hosel part 3 is 50 mm or more, the value of the moment of inertia about the axis passing through the center of gravity of the head 50 horizontally in the toe heel direction is less than 800 g · cm ² .

Further, when the length of the hosel portion 3 is less than 50 mm, the value of the moment of inertia about the axis passing horizontally through the center of gravity of the head 50 in the toe heel direction is less than 750 g · cm ² . Next, specific embodiments will be described. In order to reduce the moment of inertia, a heavy object is arranged near the center of gravity of the head.

  The iron head shown in FIG. 26 is a configuration diagram in which a heavy object 55 for reducing the vertical moment of inertia is arranged in the vicinity of the center of gravity of the head 56, and a concave groove 57 is formed on the face side near the center of gravity. A configuration in which a heavy object 55 is disposed in the groove 57 is shown. FIG. 27 is a side view of FIG. The heavy object 55 is located at the position of the center of gravity of the head 56 along the direction substantially parallel to the ground contact surface, that is, the position centered on the axis passing horizontally in the toe heel direction from the tip part on the toe part 58 side to the hosel part 59 side. Is arranged.

  A portion 60 on the sole side of the head 56 is a hollow body 62 having a cavity 61 inside. Further, although not shown in the drawings, the hollow body 62 may have a hollow shape with the upper part opened. With this configuration, the weight of the lower portion of the head is reduced, the moment of inertia is reduced, and at the same time, the rigidity of the lower portion of the head is reduced.

  The iron head shown in FIG. 28 is an example in which the head 64 is a hollow body having a cavity 65 inside, and a heavy object 63 for reducing the vertical moment of inertia is arranged near the center of gravity of the head 64. FIG. 29 is a side view of FIG. The heavy object 63 is arranged at a position near the center of gravity of the portion 66 excluding the face part. The heavy object 63 is located near the center of gravity of the head 64 and along a direction substantially parallel to the ground contact surface, that is, from the toe part 58 side to the hosel part 59 side and centering on an axis line passing horizontally in the toe heel direction. It is arranged in the middle of the position.

  The iron head shown in FIG. 30 is an example in which the head 68 is a hollow body having a cavity 65 inside, and a heavy object 67 for reducing the vertical moment of inertia is arranged in the vicinity of the center of gravity of the head 68. FIG. 31 is a side view of FIG. The heavy object 67 is disposed near the center of gravity of the back surface of the face part 69. The heavy object 67 is located in the vicinity of the center of gravity of the head 68, along a substantially parallel direction to the ground contact surface, that is, a position centered on an axis passing horizontally in the toe heel direction from the toe part 58 side to the hosel part 59 side. It is arranged in the middle part.

  The iron head shown in FIG. 32 is an example in which a heavy object 70 is arranged near the center of gravity of the back surface of the head 71. FIG. 33 is a side view of FIG. In this example, the upper portion of the hollow body 62 of the iron head shown in FIG. Similar to the iron head shown in FIG. 26, the heavy object 70 is disposed in the vicinity of the center of gravity of the head 71 and along the substantially parallel direction to the ground contact surface. That is, the heavy object 70 is disposed from the tip on the toe part 58 side to the hosel part 59 side at a position centered on an axis that passes horizontally in the toe heel direction.

  The iron head shown in FIG. 34 has an apex where a heavy object 72 for reducing the vertical moment of inertia rises upward from the lower part of the head of the portion 74 excluding the face portion at a position near the center of gravity of the head 73, that is, This is an example of arrangement near the upper end (top) 74a and in the vicinity of the center of gravity. FIG. 35 is a side view of FIG. The heavy object 72 is located in the vicinity of the center of gravity of the head 73 and along a direction substantially parallel to the ground contact surface, that is, from the toe part 58 side to the hosel part 59 side, with an axis passing horizontally in the toe heel direction as the center. And it is arrange | positioned in the intermediate part of a top part and a sole part.

  The iron head shown in FIG. 36 is a side view in which the score line 8 is shown on the face portion 2. In the iron head 1 shown in FIG. 36, the score line 8 is placed on the ground surface 11 so as to be parallel to the ground surface 11 of the sole portion 6. In this example, the position G is a position that is approximately a half of the height (vertical direction) from the top part 4 to the sole part 6 of the face part 2 surface. This position G is precisely the position projected from the center of gravity of the head 1 onto the face surface of the face portion 2 with a perpendicular line.

  A horizontal axis P passing through the position G is parallel to the score line 8 and substantially parallel to the ground plane 11. The horizontal plane including the horizontal axis P is substantially the horizontal axis P in the hitting surface of the face portion 2. In the head 1 of the present embodiment, the lower part of the substantially horizontal plane passing through the position G, that is, the sole part on the grounding surface 11 side is made low in rigidity to increase the coefficient of restitution.

  Further, if the vicinity of the position G is made heavier than other parts, the moment of inertia can be reduced. When shown in the vertical direction, the hosel portion 3 is generally closer to the top portion 4 side than the position G. For this reason, when the length (L) of the hosel part 3 is long, the center of gravity of the head 1 is relatively close to the top part 4 side. Therefore, if the length (L) of the hosel part 3 is short, the center of gravity of the head 1 is relatively close to the sole part 6 side, and as a result, the position of the center of gravity is lowered and the moment of inertia is reduced. The hosel portion length L is the length to the intersection of the upper end surface of the hosel portion, the center line of the hosel portion, and the sole surface (see FIG. 37).

  In the iron head shown in FIG. 37, the toe side of the top portion 4 is higher than the heel side (larger in a taper shape), as shown in FIGS. 27, 29, 31, 33, and 35. An example determined in consideration of the shape is shown. That is, as shown in FIG. 36, the head 1 is positioned so that the score line is horizontal.

  At this time, an angle formed between the axis parallel to the upper surface of the top portion 4 toward the hosel portion 3 and the ground contact surface 11 is defined as an intersection angle α. A line segment passing through an angle that is approximately ½ of the intersection angle α is defined as a through-axis line S. With respect to the relationship between the axis S of the through shaft and the central axis of the shaft 7, the axis S of the through shaft is an axis closer to a right angle than the axis parallel to the ground plane 11. Each of the examples of the heads shown in FIGS. 27, 29, 31, 33, and 35 described above has a structure in which a heavy object is disposed along the axis close to the through-axis S.

The specific gravity of the material constituting the main part of the head for reducing the upper and lower moments of inertia described above is preferably 6.5 g / cm ³ or more. The target iron golf club is preferably applied to a so-called short iron or wedge having a large loft angle. The embodiment of the present invention is configured as described above, but it goes without saying that the present invention is not limited to this embodiment.

Next, an experiment for showing the effect of the embodiment of the present invention was conducted. The golf club head used in the experiment relates to the iron head shown in FIGS. 32 and 33. Table 1 shows the test hit results in Examples 1 to 3. In this example, the length L of the hosel part is 54 mm, and there is no overlay on the back side except the sole part, that is, a plate-like face part is used. A heavy object 70 at the center of gravity in FIG. 32 is fixed to the plate-like face portion as a surplus, and the weight of the heavy object is 100 g. In Examples 1 to 3, the position of the heavy object was changed little by little to change the moment of inertia. The respective moments of inertia were 715 to 770 g · cm ² . The score line is formed by pressing.

In the comparative example, the moment of inertia was set to 800 g · cm ² by the same method. Conventional example 1 is a normal muscle back type wedge, and the score line is formed by a press. In Conventional Example 2, the score line is formed by engraving (cutting with a cutting tool). Compared with press molding, the angle of the score line becomes sharper, and conventionally the spin rate has been increased by this method. However, as described above, this point will be regulated in the future. The head speed was 30 m / s, and trial hits were made under the same conditions as in the conventional example and the comparative example. The result showed the effect of the example of this plan shown in FIG. 22 compared with the conventional example shown in FIG.

When the moment of inertia is 800 g · cm ^2, the amount of spin is almost the same as that of Conventional Example 1, and the amount of spin increases as the value of the moment of inertia decreases. Therefore, when the hosel length is 50 mm or more, the moment of inertia is reduced. Demonstration of less than 800 g · cm ² was obtained. From these results, when the hosel length is 50 mm or less, it is possible to realize the moment of inertia of less than 750 g · cm ² .

  20 is an example of the golf club related to the iron head shown in FIGS. 20 and 21, and Table 2 shows the test hit results in X to W of the face portion shown in FIG. 36. In this example, the thickness of the face part of the slit part was 2 mm, the slit width was 1.5 mm, and the slit depth was 30 mm from the bottom of the sole part. As shown in the figure, the test hit position is a position in the direction perpendicular to the score line, and X and Y are determined at the top portion side position, and Z and W are determined at the sole portion side position with the center of gravity position G as the boundary.

  The positions in the toe heel direction were the same at each position, and the distance between each position between the top portion and the sole portion was 5 mm. As a result, it was proved by the data in the following table 2 that the coefficient of restitution is higher on the sole portion side of the center of gravity than the conventional case without slits.

Further, the spin amount was a large value as shown in Table 3 in comparison with the conventional case. The head speed at this time is 30 m / s.

FIG. 1 is an overall view of an iron golf club. FIG. 2 is an explanatory diagram showing a state immediately before the ball is hit by the head. FIG. 3 is an explanatory view showing a state immediately after the ball is hit by the head. FIG. 4 is an explanatory view of an embodiment in which the lower portion of the head is made into a hollow body and has low rigidity. FIG. 5 is an explanatory diagram of an embodiment in which the head is a hollow body, the sole portion is made of a low Young's modulus, and the lower portion of the head is made low in rigidity. FIG. 6 is an explanatory diagram of an embodiment in which the lower part of the head is a hollow body and a high strength material is disposed on the upper part to make the lower part of the head low rigidity. FIG. 7 is an explanatory view of an embodiment in which the head is a hollow body, and a part of the lower portion of the portion excluding the face is formed as a concave groove to reduce the rigidity. FIG. 8 is an explanatory view of an embodiment in which the head is a hollow body, the thickness of the lower portion of the face is made thinner than the thickness of the upper portion, and the lower portion of the head is made low in rigidity. FIG. 9 is an explanatory diagram of an embodiment in which the head is a hollow body and a part of the lower portion of the face is recessed to make it low in rigidity. FIG. 10 is an explanatory view of an embodiment in which the head is made of a hollow body, the face is made of the same material, the upper part is made of a high hardness material, the lower part is made of a low hardness material, and the lower part of the head is made low in rigidity. FIG. 11 is an explanatory view of an embodiment in which the head is a hollow body, the upper part of the face is made of a high hardness material, the lower part is made of a low hardness material, and the lower part of the head is made low in rigidity. FIG. 12 is an explanatory diagram of an embodiment in which the head is a hollow body, the portion other than the face is made of the same material, the upper part is made of a high hardness material, the lower part is made of a low hardness material, and the lower part of the head is made low in rigidity. FIG. 13 is an explanatory diagram of an embodiment in which the head is a hollow body, the upper part of the portion excluding the face is made of a high hardness material, the lower part is made of a low hardness material, and the lower part of the head is made low in rigidity. FIG. 14 is an explanatory diagram of an embodiment in which the head is a hollow body, the upper part of the face is made of a high Young's modulus material and the lower part is made of a low Young's modulus material, and the lower part of the head is made low in rigidity. FIG. 15 is an explanatory diagram of an embodiment in which the head is a hollow body, the upper part of the portion excluding the face is made of a high Young's modulus material and the lower part is made of a low Young's modulus material, and the lower part of the head is made low in rigidity. FIG. 16 is an explanatory diagram of an embodiment in which a substantially horizontal through-groove is provided at the position of the center of gravity of the back surface of the head to make the lower portion of the head low rigidity. FIG. 17 is a side view of FIG. FIG. 18 is an explanatory diagram of an embodiment in which a pocket concave groove that is open on the toe side is provided at the position of the center of gravity of the back surface of the head to make the lower portion of the head low rigidity. FIG. 19 is a side view of FIG. FIG. 20 is an explanatory diagram of an embodiment in which a slit-like groove is provided in the lower part of the head in the direction perpendicular to the ground surface to make the lower part of the head low rigidity. FIG. 21 is an explanatory view of an embodiment in which an elastic body is arranged in the slit-shaped concave groove having the same shape as in FIG. FIG. 22 is an explanatory diagram showing that the inertia moment in the head vertical direction is reduced. FIG. 23 is an explanatory diagram showing a situation of a conventional moment of inertia. FIG. 24 is an explanatory view showing a state immediately before the ball collides with the head, which is the same shape as FIG. FIG. 25 is an explanatory view showing a state immediately after the ball collides with the head, in the same shape as FIG. FIG. 26 is an explanatory diagram of an embodiment in which a heavy object is provided in a concave groove on the face side near the center of gravity of the head to reduce the moment of inertia. FIG. 27 is a side view of FIG. FIG. 28 is an explanatory diagram of an embodiment in which the head is a hollow body and a heavy object is arranged at the position of the center of gravity of the portion excluding the face to reduce the moment of inertia. FIG. 29 is a side view of FIG. FIG. 30 is an explanatory diagram of an embodiment in which the head is a hollow body and a heavy object is disposed in the vicinity of the center of gravity of the face to reduce the moment of inertia. FIG. 31 is a side view of FIG. FIG. 32 is an explanatory diagram of an embodiment in which a heavy object is arranged in the vicinity of the center of gravity of the back surface of the head to reduce the moment of inertia. FIG. 33 is a side view of FIG. FIG. 34 is an explanatory diagram of an embodiment in which a heavy object is arranged in the vicinity of the center of gravity of the end rising from the lower part of the sole part excluding the face to reduce the moment of inertia. FIG. 35 is a side view of FIG. FIG. 36 is a side view of a head showing a face portion provided with a score line. FIG. 37 is an explanatory diagram of a head showing a through shaft having an angle with respect to an axis parallel to the ground plane.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 50 ... Head 2, 21 ... Face part 3, 59 ... Hosel part 4 ... Top part 5, 58 ... Toe part 6 ... Sole part 7 ... Shaft 8 ... Score line 9 ... Center of gravity part 10 ... Balls 20, 23 ... Cavity 42 ... concave groove 55 ... heavy object

Claims (8)

A sole part (6) having a ground contact surface at the bottom, a top part (4) at the top, a face part (2) having a ball striking surface for hitting a ball, and a hosel part (3) as a shaft connection part at one end; A head (1) comprising:
In an iron golf club comprising a shaft (7) having one end connected to the hosel part,
An iron golf club characterized in that the ground surface side of the head (1) is configured with low rigidity. 2. The iron golf club according to claim 1, wherein the top portion (4) side of the head (1) is configured to have relatively higher rigidity than the ground contact surface side. The iron golf according to claim 1, wherein the grounding surface side of the head (1) has a relatively high coefficient of restitution compared to the top portion (4) side of the head (1). club. The iron according to any one of claims 1 to 3, wherein the ground surface side of the head (1) is in a range on a sole portion side from a substantially horizontal plane passing through the center of gravity and parallel to the score line. Golf club. A sole part (6) having a ground contact surface at the bottom, a top part (4) at the top, a face part (2) having a ball striking surface for hitting a ball, and a hosel part (3) as a shaft connection part at one end; A head (50) comprising:
In an iron golf club comprising a shaft (7) having one end connected to the hosel part,
When the length (L) of the hosel part (3) is 50 mm or more, the value of the moment of inertia about the axis passing through the center of gravity (9) of the head (50) horizontally in the toe heel direction is 800 g · cm. An iron golf club characterized by being less than ^two . A sole part (6) having a ground contact surface at the bottom, a top part (4) at the top, a face part (2) having a ball striking surface for hitting a ball, and a hosel part (3) as a shaft connection part at one end; A head (50) comprising:
In an iron golf club comprising a shaft (7) having one end connected to the hosel part,
When the length (L) of the hosel part (3) is less than 50 mm, the value of the moment of inertia about the axis passing through the center of gravity (9) of the head (50) horizontally in the toe heel direction is 750 g · cm. An iron golf club characterized by being less than ^two . The iron golf club according to any one of claims 1 to 6, wherein a specific gravity of a material constituting a main part of the head (50) is 6.5 g / cm ³ or more. The iron golf club according to any one of claims 1 to 7, wherein the head (50) is a short iron head or a wedge head.

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