JPH04288173A - Ball shooting tool - Google Patents

Abstract

PURPOSE:To increase the restitution coefficient of a ball for elongating a carry of the ball by reducing the loss of kinetic energy due to friction in collision of the ball with a ball shooting tool. CONSTITUTION:At least a ball hitting face part 11a of a ball shooting tool body 11 is formed of a titanium alloy of diamond-shaped carbon (DLC), TiN, TiAlN, TiC, etc., or ceramics or thermit of ZrO2, Al2O3, etc., and the surface is subjected to mirror finish so that the Vicker's hardness of the surface of the ball hitting face part exceeds at least Hv1000kg/mm<2> and the coefficient of friction mu of the surface is about 0.02. The loss of kinetic energy due to the friction between a ball and a ball shooting tool can be reduced to 1% or less. The restitution coefficient of the ball can be increased by about 10% or more of conventional ones to elongate the carry of the ball by about 5% or more.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of flying ball implements such as golf wood clubs, iron clubs, baseball bats, etc., and more particularly to improvements in the ball hitting surface of such flying ball implements.

0002

[Prior Art] Conventionally, there have been golf wood clubs, iron clubs, and golf clubs aimed at extending the flight distance of the ball.
In flying ball implements such as baseball bats, at least the ball-hitting surface is made of various materials such as wood, metal, and fiber-reinforced resin. The structure is such that friction occurs.

0003

[Problem to be solved by the invention] When friction occurs due to the elastic deformation of the ball on the contact surface with the ball during a collision, kinetic energy is lost, resulting in a decrease in the ball's coefficient of restitution and a decrease in the ball's flight speed. The ball flight distance decreases. Therefore, we will consider the influence of friction on the ball flight speed.

First, consider a situation in which a ball collides with a fixed wall. Figure 5(a) shows the state of frictional force generation when the amount of axial compression of the ball due to collision is increasing.
FIG. 5(b) shows a state in which the amount of axial compression is recovering from the maximum compression state. As shown in Fig. 5(a), when friction occurs between the ball and the wall surface during compressive deformation of the ball, the friction increases while the contact area of the ball with radius r increases by a small amount dr in the radial direction. The kinetic energy dWr lost due to dWr can be calculated using Equation 1.

[0005]

[Math 1]

[0006] Here, μ is the coefficient of friction between the ball and the wall, and F is the force applied to the wall due to the collision of the ball. Further, ν represents the Poisson's ratio of the ball, and dδ represents the minute increment of the amount of deformation δ in the axial direction (direction of collision) of the ball. Therefore, dδ/r on the right side of the second line of Equation 1 indicates the axial distortion, the term on the right side indicates the radius of the outermost edge of the contact surface, and (1/root 2) represents the entire contact surface of the ball. This is a coefficient for averaging the amount of deformation in the radial direction.

According to experiments, when a golf ball weighing 45.9 g collides with a wall at a speed of 40 m/sec, the force F applied to the wall is approximately 3.8×10 7 N. Therefore, the kinetic energy Wr lost due to friction until the amount of axial deformation δ of the ball reaches the maximum value δ0
can be determined by equation 2.

[0008]

[Math 2]

On the other hand, if the mass of the ball is m and the initial velocity of the ball at the start of the collision is v1, then the kinetic energy W1 of the ball at the initial velocity v1 and the maximum deformation amount δ0 of the ball
can be determined using Equation 3, respectively.

0010

[Math 3]

As can be seen from FIGS. 5(a) and 5(b), contact friction between the ball and the wall occurs while the amount of ball compression increases and while the ball recovers, so the ball collides with the wall. The kinetic energy lost due to friction between the time it hits the wall and the time it flies off the wall is 2Wr. Therefore, the residual rate Rw of the ball's kinetic energy when the ball flies out from the wall surface, and the ball's flying velocity v
2 and the coefficient of restitution e of the ball can be determined by equation 4, respectively.

0012

[Math 4]

On the other hand, the surface hardness of the ball-hitting surface of the head of a conventional wood club or the like is Hv800 kg/mm2 or less, and the contact friction coefficient μ with the ball is about 0.5 when the surface is relatively smooth. Also, a typical golf ball has a mass m of about 45.9 g and a radius r of about 21.3 mm.
, Poisson's ratio ν is approximately 0.48. For example, when a head weighing 200g collides with a golf ball at a speed of 40m/sec2, the maximum compression amount of the ball is approximately 5.7m.
m. Therefore, if the wall surface is made of the same material as a conventional wood club head, etc., and the maximum compression amount δ0 when a golf ball collides with this wall surface is 5.7 mm, then if the wall surface has a friction coefficient μ of 0.5, , from Equations 1 to 4, the residual energy rate Rw at the time of collision is 0.804, and it can be seen that 19.6% of the kinetic energy is lost due to friction between the ball and the impact surface of the flying ball. The ball has a coefficient of restitution e of 0.897. Therefore, using the coefficient of restitution e of the ball determined by Equation 4, the flight velocity vb of the ball when the club head of mass M collides with the ball at velocity vh can be determined by Equation 5.

[0014]

[Math 5]

In Equation 5, the head speed vh is set to 40 m.
/sec, and the head mass M is 200 g, and when the ball's coefficient of restitution e is 0.897, the ball launch speed vb is approximately 61.7 m/sec. According to experiments,
If the flight speed of the ball changes by 1%, the flight distance of the ball will also change by about 1% (for example, about 2m compared to a flight distance of 200m). It can be seen that the kinetic energy loss due to friction cannot be ignored.

However, conventionally, for example,
As seen in Publication No. 877, there has been a tendency to further increase the coefficient of friction μ by providing unevenness on the surface of the face member, which further increases the amount of kinetic energy loss and reduces the flight distance of the ball. It had become.

In view of the above-mentioned problems of the prior art, it is an object of the present invention to increase the coefficient of restitution of the ball by reducing the amount of kinetic energy loss due to friction during collision between the ball and the flying ball. To provide a ball flying device capable of extending the flying distance of a ball.

[0018]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, at least the ball hitting surface portion of the main body of the flying ball tool is formed of a hard material having a surface Vickers hardness of Hv1000 kg/mm2 or more, and It is characterized by a mirror finish on the ball hitting surface.

As the hard material, for example, diamond-like carbon (DLC), titanium alloys such as TiN, TiAlN, TiC, ceramics such as ZrO2, Al2O3, etc., or cermet (ceramic-metal microcrystalline composite material) may be used. Can be done. Diamond-like carbon (DLC), TiN, TiAlN, Ti as hard materials
When using a titanium alloy such as C, the Vickers hardness of the ball hitting surface can be set to Hv2000 kg/mm2 or more. When using these hard materials, a film of the hard material is directly coated on at least the ball hitting surface of the ball flying tool body by vacuum deposition using CVD, PVD, etc., or a recess is formed on the ball hitting surface of the ball flying tool body. Preferably, a film of hard material is formed in a similar manner on the surface of the face plate that is mounted within the recess. In addition, when ceramics or cermets such as ZrO2, Al2O3, etc. are used as the hard material, a face plate made of these hard materials is installed in the recess formed in the ball hitting surface of the fly ball tool body, or the entire fly ball tool main body is Preferably, it is made of a hard material. ZrO2 has a surface hardness of Hv115.
0 to 1250 kg/mm2, Al2O3 has a surface hardness of Hv1000 to 2300 kg/mm2, and cermet has a surface hardness of Hv1500 to 1650 kg/mm2.

[0020]

[Function] In the flying ball device having the above configuration, the friction coefficient μ of the surface of the hard film formed on the ball hitting surface can be set to about 0.02, so that the friction between the ball and the flying ball device can be reduced. The loss of kinetic energy can be reduced to about 1% or less, and the coefficient of restitution of the ball can be increased by about 10% or more compared to the conventional standard flight ball device, so the flight distance of the ball can be increased by about 5%. It can be extended more than that.

[0021]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4. In order to facilitate understanding, the same or similar components in these figures are given the same reference numerals.

FIGS. 1 and 2 show a first embodiment in which the present invention is applied to a wood club for golf. Referring to these figures, the wood club has a hollow head body 11 made of metal, fiber-reinforced resin, fiber-reinforced metal, or the like. Ball hitting surface portion 11 of this head body 11
A recess is formed in a, and a hard metal face plate 12 made of tool steel, alloy tool steel, carbide material, etc. is fixed in the recess. A hard material film 13 made of one of diamond-like carbon, TiN, TiAlN, or TiC is deposited on the surface of the face plate 12 to a thickness of several μm, for example, by a vacuum deposition method known per se using CVD or PVD. It is formed to have a film thickness of 1 to 5 μm, and its surface is mirror-finished. Although a face line (groove) is formed in the ball hitting surface portion 11a of the head body 11 shown in FIG. 2, this face line may be omitted.

In the golf club having the above configuration, the Vickers hardness of the surface of the hard material film 13 on the face substrate 12 forming the ball hitting surface portion 11a of the head body 11 is at least Hv2000 kg/mm2, and the surface Due to the mirror finish, the friction coefficient μ is 0.0
It will be about 2.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, the recess and the face substrate in the first embodiment are omitted, and the ball hitting surface portion 11 of the head body 11 is
diamond-like carbon, TiN over the entire surface including a
, TiAlN, or TiC is formed to a thickness of several μm, for example, 1 to 5 μm, by the same method as in the above embodiment, and furthermore, its surface is mirror-finished. There is.

Therefore, in this embodiment as well, the hard material film 13 forming the ball hitting surface portion 11a of the head body 11 is
The Vickers hardness of the surface is Hv2000kg/mm2
As a result, the friction coefficient μ of the surface becomes approximately 0.02.

FIG. 4 shows a third embodiment of the present invention. In this embodiment, the head body 1 is similar to the first embodiment.
A recess is formed in the first ball hitting surface portion 11a, and a face plate 14 made of ceramics such as ZrO, Al2O3, or cermet is fixed in the recess. The surface of this face plate 14 is mirror finished.

In this third embodiment, the Vickers hardness of the surface of the face plate 14 made of ceramics or cermet is at least Hv1000 kg/mm2.
As a result, the friction coefficient μ of the surface becomes approximately 0.02.

Applying the value of the friction coefficient μ in each of the above-mentioned examples to the above-mentioned Equations 1 to 4, the energy residual rate Rw at the time of collision becomes 0.992, and the ball's repulsion coefficient e becomes 0.996. . In other words, the kinetic energy lost due to friction between the ball and the impact surface of the flying ball is less than 1%, reducing the ball's coefficient of restitution to about 11 compared to that of a conventional standard golf club (μ = 0.897). % can be increased. From Equation 5, the ball launch velocity vb is approximately 64.9 m/sec, which is compared to the ball launch velocity (vb = 61.7 m/sec) of a conventional standard golf club (μ = 0.897). This will result in an increase of approximately 5%. Therefore, the flight distance of the ball is also approximately 5% (2
00m).

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the aspects of the above embodiments, for example, the manner in which the face plate is attached to the head body, the internal structure of the head body itself, etc. Various changes can be made to . Furthermore, when ceramics are used as the hard material, the entire head body 11 can be formed of ceramics or cermet. Furthermore, the present invention can be applied to various flying ball implements such as iron clubs, baseball bats, etc. in addition to the illustrated wood clubs.

[0030]

As is clear from the above description, according to the present invention, the loss of kinetic energy due to friction between the ball and the collision surface of the flying ball can be reduced to about 1% or less, and the coefficient of restitution of the ball can be improved. It is possible to provide a flying ball device that can increase the distance of the ball by about 10% or more compared to a conventional standard flying ball device and extend the flight distance of the ball by about 5% or more.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a golf wood club head showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the club head shown in FIG. 1.

FIG. 3 is a longitudinal sectional view of a wood club head showing a second embodiment of the present invention.

FIG. 4 is a vertical sectional view of a golf club head showing a third embodiment of the present invention.

[Figure 5] Diagrams showing the state in which the ball collides with the flying ball, (a) shows the state where the compressive deformation is increasing, (b)
indicates a state where compressive deformation is decreasing.

[Explanation of symbols]

11 Head body 11a Ball hitting surface part 12 Face plate 13 Hard material film

Claims (7)

[Claims] 1. A flying ball tool, wherein at least the ball hitting surface of the ball flying tool main body is made of a hard material having a surface Vickers hardness of Hv1000 kg/mm2 or more, and further, at least the ball hitting surface is mirror-finished. 2. The flying ball tool according to claim 1, wherein the surface of the hard material has a Vickers hardness of Hv2000 kg/mm2 or more. 3. The hard material is diamond-like carbon,
TiN, TiAlN, TiC, ZrO2, Al2O3
The flying ball tool according to claim 1, comprising any one of: or cermet. 4. The flying ball tool according to claim 1, wherein the hard material is coated on at least the surface of the ball hitting surface portion of the main body of the flying ball tool. 5. The flying ball device according to claim 1, wherein a face plate is mounted in a recess formed in a ball hitting surface of the main body of the flying ball device, and the hard material is coated on the surface of the face plate. 6. The flying ball tool according to claim 1, wherein the face plate made of the hard material is mounted in a recess formed in the ball hitting surface of the flying ball tool main body. 7. The flying ball tool according to claim 1, wherein the entire main body of the flying ball tool is made of the hard material.