JP2001062002A - Hollow golf club head and golf club formed by mounting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the noise generated by the movement of the foreign matter generated by dislogment from the inside surface of a hollow head of a golf club, etc., in the head and to obtain a good ball hitting feed of a gold club by applying a tacky adhesive resin to the inside surface of the hollow head. SOLUTION: A method for fixing a core by core sand into molds and casting the head 1 of a hermetic shell structure, then breaking the core and removing the sand from a take-out hole or a method putting a tubular bag, on which a composite material layer is formed, into the molds and molding the material to a hermetic shell structure, then removing the tubular bag is adopted when the hollow head 1 is produced by using a metallic material or composite material. There is a tendency that the dislodged materials of the sand, resin, etc., remain on the inside surface of the hollow head in both of these methods. The tacky adhesive resin is, thereupon, applied to the inside surface of the head 1, by which the capturing of the foreign matter, such as the and or resin pieces, is made possible and the generation of the noise by the movement of the foreign matter in the head 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hollow golf club head (hereinafter simply referred to as a head).

[0002]

2. Description of the Related Art In a golf club of a wood type such as a driver, a spoon, and a buffy, the flying distance and controllability (direction) of a ball are regarded as important. It is known that the flight distance and controllability of the ball are greatly affected by the moment of inertia about the center of gravity of the head, and since the moment of inertia increases in proportion to the volume of the head, recently, drivers, Wood type golf club heads such as spoons and buffies are mainly hollow type heads made of metal materials such as stainless steel, titanium alloy, and aluminum alloy in order to increase the moment of inertia. Are also increasing in size.
In such a head, the flight distance is increased, the sweet spot is enlarged, and the bend of the hit ball is reduced as compared with a solid type head typified by a conventional Persimmon head.

[0003]

When manufacturing a head using a metal material or a composite material, a core is made of core sand, the core is fixed in a mold, and a head having a closed shell structure is formed. After casting, a method is used in which the core is broken and sand is removed from the extraction hole.

On the other hand, when manufacturing a head with a composite material, a tube-like bag made of nylon or the like is used as a substitute for the core, a composite material layer is formed thereon, and then put in a mold and sealed. A method of forming a shell structure and removing the tubular bag after molding is also employed.

When core sand is used, it is difficult to completely remove the core sand adhered to the inner surface of the head, and the sand that has fallen off due to the impact force during use of the golf club stays in the head, and the golf club cannot be used. When using or transporting the device, abnormal noise was generated, which sometimes affected the shot feeling. Also, when a tubular bag is used, resin protrusions and thin films formed on the inner surface of the head due to wrinkles of the tubular bag during molding fall off due to the impact force during use of the golf club, and core sand is formed. In the same way as above, abnormal noise was generated, which sometimes affected the shot feeling. This problem is becoming more prominent as the size of the head increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a golf club head which suppresses abnormal noise caused by foreign substances generated by falling off from the inner surface of the hollow head and moving in the head, and which does not reduce the shot feeling of the golf club. And

[0007]

A first gist of the present invention is as follows.
A hollow golf club head is formed by applying an adhesive resin to the inner surface of the head.

The present invention also relates to the above-mentioned head, wherein the head has a weight of 200 g or less and a volume of 300 to 900 c.
c, A hollow head having a minimum thickness of 4 mm or more in the face portion is a preferable mode. Specific strength is 30 kg / mm ²
The above-mentioned head made of the above materials is also a preferable embodiment.

According to the present invention, the head having a moment of inertia of 4 × 10 ⁻⁴ kg · m ² or more is a further preferred form.

Further, the present invention resides in the use of a carbon fiber bidirectional reinforced epoxy resin or the like as the material having a specific strength of 30 kg / mm ² or more in the above invention. Second embodiment of the present invention
The gist of the present invention resides in a golf club equipped with the above hollow head.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The head of the present invention requires that an adhesive resin be applied to the inner surface of the head. Thereby, even if resin protrusions, thin films formed on the inner surface of the head during molding of the head, or core sand fixed to the inner surface of the head and cannot be removed fall off due to the impact of a hit ball, these are supplemented, and inside the head. It is possible to suppress the abnormal noise caused by the movement of the resin pieces and sand.

The adhesive resin is applied to the whole or a part of the inner surface of the head. Even if applied to a part, the resin pieces and sand move by vibration and can be captured by the adhesive resin. In the present invention, the material of the adhesive resin is not particularly limited as long as the resin pieces and sand can be supplemented, but a silicone resin, a vinyl acetate resin, or the like can be given as a preferable example.
It is appropriate to apply in the range of 1 to 10 mm.

The adhesive resin can be sprayed onto the entire inner surface of the head with a spray gun from a hosel hole or a core sand take-out hole in the neck of the head, or applied to a part of the head with a syringe.

Next, the reason why the bending of the hit ball is reduced by increasing the moment of inertia of the head, which is a preferred embodiment of the present invention, and a decrease in the flight distance due to this will be described.

When a golf club hits a golf ball (hereinafter, simply referred to as "ball"), the collision force between the head and the ball is expressed by the following equation (1). Impact force = head weight x head acceleration (1)

On the other hand, the impact force corresponds to a change in momentum received by the ball during the impact time, and is represented by the following equation (2). Impact force = ball weight x (ball initial speed x 2) / impact time (2)

The collision time between the ball and the head when the ball impacts on the golf club is actually measured to be 5 / 10,000 seconds by a technique such as flash photography. On the other hand, the weight of the ball is set at 46 g. Therefore, if the initial velocity of the ball is 50 m / sec, a load of 940 kg acts on the ball at the moment of impact.

Incidentally, it has been found by measurement that the deformation of the club shaft upon impact of the ball is zero. Therefore, at the time of impact, only kinetic energy is exchanged between the ball and the head, and it is assumed that a part of the kinetic energy of the head is transferred to the ball.

Therefore, the flight distance of the ball is proportional to the kinetic energy of the head (ie, head weight × speed ² ). That is, in order to extend the flight distance, one or both of the head weight and the head speed may be increased. However, if this is increased unnecessarily, there is a problem that it is practically difficult to catch the ball at the sweet spot on the striking surface of the head.

The sweet spot here refers to a point at which a straight line passing through the center of gravity of the head intersects the head's striking surface (face) at right angles. If the ball does not hit the sweet spot of the head, the ball fluctuates in the ball flying direction. Assuming that the loft angle of the face is 0 degrees, the deflection of the ball in the flight direction in the horizontal plane is calculated as follows.

When the ball hits outside the sweet spot of the head, a rotational torque is generated around the vertical axis passing through the center of gravity of the head, and the head rotates. This rotation torque is calculated by the following equation. Here, it is assumed that the user hit the ball 3 cm left or right in the horizontal plane from the sweet spot. Rotational torque = collision force × distance from center of gravity to impact point (3) = 940 × 0.03 = 28.2 kg · m (3 ′) The rotational energy of the head is: rotational energy = moment of inertia × angular acceleration (4) ).

Since the rotational energy and the rotational torque are balanced, the angular acceleration during the rotation of the head can be obtained from the equations (3 ') and (4). Here, the moment of inertia of the head is set to 2 × 10 ⁻⁴ kg · m ² of a general head. Angular acceleration = 28.2 kg · m × 9.8 m / Sec ² ÷ 2 × 10 ⁻⁴ kg · m ² = 1.38 × 10 ⁶ rad / sec ^{2 When} this angular acceleration is multiplied by the collision time to obtain the rotation speed,
1.38 × 10 ⁶ × 0.0005 = 690 rad / se
c, and the rotation angle is expressed by the following equation (5), and 9.9 is obtained.
Calculated as degrees. Rotation angle = angular acceleration x (collision time) ² 2 (5)

From the above calculations, if the ball is hit 3 cm away from the sweet spot of the head,
It turns out that it rotates 9.9 degrees in / 10000 seconds.
For this reason, the rotation angle of the head shifts the launch angle of the ball leftward or rightward.
In the case of a flight distance of m, approximately 30 m is shifted leftward or rightward from the target point.

Further, the rotational movement of the head is applied to the ball.
Consumes part of the kinetic energy of the head to be transmitted
The ball's flight distance.
You. When calculating the decrease in flight distance, the kinetic energy of the head
ー is weight x (head speed) ^TwoIs represented by $ 2
With a head weight of 200g and a head speed of 50m /
If it is sec, it will be 250J. On the other hand, the head rotation
Energy is moment of inertia x (rotational speed)^TwoTable with $ 2
The moment of inertia is 2 × 10^-Fourkg ・
m^TwoAnd the rotation speed is 690 rad / sec.
It becomes 48J. In other words, the head rotated when hitting
Sometimes about 20% of the kinetic energy of the head is lost
As a result, the flight distance is shortened by about 20%.

When the above-mentioned theoretical calculation is performed while changing the moment of inertia of the head and the deviation of the ball from the target point and the decrease in the flight distance are obtained, the results shown in the graphs of FIGS. 1 and 2 are obtained. . The vertical axis in FIG. 1 represents the deviation of the ball (bending of the hit ball) from the target point in the case of a flight distance of 200 m, and the vertical axis in FIG. 2 represents the decrease in the flight distance corresponding to the kinetic energy loss ratio. The horizontal axes of the graphs in FIGS. 1 and 2 represent the moment of inertia of the head. In the graphs of FIGS. 1 and 2, theoretical calculations were performed in the same manner as described above, except that the head weight was 200 g, the head speed at impact was 40 m / sec, and the deviation of the ball hit point from the sweet spot was 2 cm.

From these graphs, it can be seen that by increasing the moment of inertia of the head, the bend of the ball is reduced even if the hit point of the ball slightly deviates from the sweet spot of the head, and the decrease in the flight distance is thereby reduced. Understand.

FIG. 3 shows the moment of inertia in the present invention.
As shown in FIG. 2, when the sole 2 of the head 1 is placed so as to land on a horizontal plane, that is, when the head 1 is in a normal use position, the moment about the vertical axis H passing through the center of gravity G is referred to. In FIG. 3, reference numeral 3 denotes a face, 4 denotes a crown, and 5 denotes a neck.

The measurement of the moment of inertia is performed by a two-pending pendulum method using the apparatus shown in FIG. FIG.
In the figure, reference numeral 1 denotes a cross section of the head.
Is mounted on a support 6 having a flat disk-shaped moment of inertia. The support 6 is suspended from the base 8 by two wires 7, 7. First, in this state, the support base 6 is opened after being twisted and freely rotated,
The period T at that time is measured. Next, from the period T measured here, the moment of inertia Ig of the head is calculated by the following equation (6).

[0029]

(Equation 1)

In FIG. 4, a is 1/2 of the fixed distance of the wires 7, 7 on the support 6; b is 1/2 of the fixed distance of the wires 7, 7 on the base 8; The distance from the support 6 is shown.

As described in detail above, by increasing the moment of inertia of the head, the bending of the hit ball can be reduced, and the decrease in the flight distance can be reduced. To increase the moment of inertia of the head, the size of the head may be increased. However, if the weight of the head is unnecessarily increased when the size of the head is increased, a swing or the like becomes difficult. Therefore,
In practice, the upper limit of the head weight is 200 g. Therefore, in order to increase the size while keeping the weight of the head constant, it is necessary to make the structure of the head hollow and make the volume as large as possible.

However, for example, when the head weight is 200 g and the volume which is an index indicating the size of the head is 300 c.
c, When a large hollow head having a moment of inertia of 3 × 10 ⁻⁴ kg · m ² , which is another index indicating the size of the head, is made of a metal material such as stainless steel, a titanium alloy, or an aluminum high-strength alloy, The thickness of the head must be reduced, and as a result, the head may be broken by the impact at the time of hitting the ball. When a larger head having a moment of inertia of 4 × 10 ⁻⁴ kg · m ² is made of these metal materials, a portion such as a face portion having a thickness of 1 mm or less occurs.
Experiments have confirmed that the ball actually breaks when hit.

The reason for this is that the specific gravity (tensile strength (kg / mm ² ))
/ Specific gravity) is reduced. Actually, the specific strength of these metallic materials is 14 to 16 kg / mm ² , and the upper limit of the moment of inertia of the head is 3 × 10 ⁻⁴ kg · m ² for materials having such specific strength. Therefore, it is difficult to increase the size (volume) of the head and increase the moment of inertia in the head made of the metal material.

However, as can be seen from the graphs of FIGS. 1 and 2, in order for the amount of bending of the hit ball and the decrease in the flight distance to be within an allowable range, at least the moment of inertia of the head is 4 × 10 ⁻⁴ kg. · desirably m is ² or more, it is necessary to set the volume of the head to obtain the moment of inertia of this range above 300 cc.

On the other hand, if the volume of the head is increased, the thickness of the face portion must be reduced, and such a head may be damaged at the time of hitting a ball. Specifically, to prevent the hollow head from being damaged when hitting a ball,
It is necessary to use a material having a specific strength of 30 kg / mm ² or more and a head volume of 9 mm or more.
As a result of examination, it has been found that it is necessary to set the pressure to 00 cc or less.

As a material having a specific strength of 30 kg / mm ² or more, carbon fiber, glass fiber, aramid fiber, polyester fiber and the like are reinforced with a matrix resin such as an epoxy resin, an unsaturated polyester resin and a vinyl ester resin. Although there is a fiber reinforced plastic, carbon fiber is preferable as the reinforcing fiber in terms of strength. In particular, it is preferable to use carbon fiber oriented in two orthogonal directions because impact resistance can be ensured. When a high elasticity and high density component such as tungsten powder is dispersed in the matrix resin, the vibration characteristics of the head can be improved and the sound when hit can be improved.

In the case of carbon fiber bidirectional reinforced epoxy resin using orthogonal bidirectionally oriented carbon fiber as reinforcing fiber and epoxy resin as matrix resin, the carbon fiber content is preferably in the range of 40 to 70% by volume. Has a specific strength of 35 to 60 kg / mm ² . As the carbon fiber bidirectional reinforced epoxy resin, specifically, a prepreg obtained by impregnating an uncured epoxy resin into a roving cloth, a plain weave cloth, or the like made of a high elastic carbon fiber, for example, "Pyrofil TR3110-340" manufactured by Mitsubishi Rayon Co., Ltd. Etc. can be used.

In order to prepare a head made of a carbon fiber bidirectional reinforced epoxy resin, for example, the prepreg is cut into a required shape, and a required number of pieces are laminated on the inner surface of a halving female mold for molding. Next, a tube-shaped bag made of nylon or the like is arranged inside when the two-piece female mold is combined. Next, the mold is placed in a heating furnace, and simultaneously with heating, pressurized air is injected into the bag, and the laminated pre-leg is cured while being pressed against the mold.

The specific strength is 35 kg with the carbon fiber content of 40% by volume.
/ Creating a hollow head volume 400cc with carbon fiber bidirectional reinforced epoxy resin mm ^2, the moment of inertia is 4 × 10 ^-4 kg · m ^2, and the applying the moment of inertia of sufficient magnitude to head Can be. And
In this case, the thickness of the head is 3 mm at the thinnest portion, and the minimum thickness is 6 mm at the face portion, so that the head can have sufficient breaking strength, and there is no possibility of breaking due to impact at the time of hitting a ball.

In addition to the carbon fiber two-way reinforced epoxy resin, the material having a specific strength of 30 kg / mm ² or more and which can be used for the head of the present invention is expensive, There is.

The golf club head of the present invention has a head volume of 300 cc or more and has a higher moment of inertia than that of the conventional head. Preferably, the value of the moment of inertia is 4 × 10 ^-4 kg · m ² or more. Therefore, even when the ball hits the ball slightly out of the sweet spot on the face of the head, the bending of the ball is small, and the decrease in the flight distance due to the bending of the ball can be reduced.

Further, since a material having a specific strength of 30 kg / mm ² or more is used, the thickness of the head can be increased even if the moment of inertia is increased, and the destruction of the head due to a hit ball or the like can be prevented. it can. Especially in the face part which receives an impact, the minimum thickness of the face is set to 4mm or more so that stress is not concentrated on a part of the face. can do.

In the head of the present invention, a metal plate is disposed on the sole to lower the position of the center of gravity, a back metal is attached to move the position of the center of gravity backward, and a balance weight or foam is provided inside the hollow. A body can also be provided.

[0044]

The present invention will be described more specifically with reference to specific examples below. (Example) "Pyrofil TR3110" manufactured by Mitsubishi Rayon Co., Ltd. as a carbon fiber woven fabric reinforced epoxy resin prepreg.
-340 "(carbon fiber content 40% by volume), this prepreg is cut into a predetermined shape, and the required number of pieces are laminated orthogonally in two directions on the inner surface of a halving female mold for molding. Was placed on the outermost layer, and when assembling the molds together, a nylon tubular bag was placed inside.

This female mold was placed in a heating furnace and the temperature was set to 130.
At the same time, heating was performed at a temperature of 1 ° C. for 1 hour, and simultaneously, pressurized air having a pressure of 4 kgf / cm ² was injected into the nylon bag. After curing, the mold was cracked to obtain the desired head, and the nylon tubular bag was removed. This head has a specific strength of the carbon fiber woven epoxy resin used of 60 kg · m ² , a weight of 180 g, a moment of inertia of 6.0 × 10 ⁻⁴ kg · m ² , and a volume of 700 c.
c, the minimum thickness of the face portion was 5 mm, and the loft angle was 13 degrees.

Wacker Chemicals Co., Ltd. Wacker Chemicals Co., Ltd.
Inject 1 g of ilGel612 with a syringe,
Heating was performed for 0 minutes to form a 1 mm thick adhesive resin region on a part of the inner surface of the head.

A golf club was obtained by attaching a carbon fiber woven fabric epoxy resin shaft to the head. The golf club was attached to a swing robot, and the head speed was set at 50 m / sec, and the golf club was not damaged even when repeatedly hit 1000 times. When the golf club was set to a head speed of 40 m / sec and subjected to a field test by a swing robot, the ball was concentrated in a range of several meters at a landing point 200 m away from the tee shot point. Was confirmed.

[0048]

According to the head of the present invention, since the adhesive resin is applied to the inner surface of the head, generation of abnormal noise due to falling off of resin pieces and sand on the inner surface of the head can be suppressed. Furthermore, the golf club has a very small bending of the ball when hit with a ball as compared with a conventional head, so that it is possible to obtain a golf club which does not fly and bends without a decrease in flight distance. Moreover, since the thickness of the face portion is sufficiently ensured, the club head is not damaged at the time of hitting the ball.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the moment of inertia and the bending of a hit ball.

FIG. 2 is a graph showing a relationship between a moment of inertia and an amount of decrease in a flight distance.

FIG. 3 is an explanatory diagram for explaining the definition of a moment of inertia.

FIG. 4 is a schematic configuration diagram illustrating a measuring device of a moment of inertia.

[Explanation of symbols]

 1 Head 2 Sole 3 Face 4 Crown 5 Neck 6 Support 7 Wire 8 Base

Claims (6)

[Claims] 1. A hollow golf club head comprising an inner surface of a hollow head coated with an adhesive resin. 2. The weight of the hollow head is 200 g or less, the volume is 300 to 900 cc, and the minimum thickness of the face portion is 4 mm.
The hollow golf club head according to claim 1, which is as described above. 3. The hollow golf club head according to claim 1, wherein the golf club head is made of a material having a specific strength of 30 kg / mm ² or more. 4. A head having a moment of inertia of 4 × 10 ^−4.
The hollow golf club head according to claim 1, wherein the weight is not less than kg · m ² . 5. The hollow golf club head according to claim 1, wherein the head is made of a carbon fiber bidirectional reinforced epoxy resin. 6. A golf club provided with the hollow golf club head according to claim 1.