JP2001029515A - Iron golf club and iron golf club set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the amount of backspin by a club making it from a material whose angle of contact with water and Vickers hardness are specified, and providing a ball striking portion, the 10-point average roughness of the surface of which is specified. SOLUTION: The heat H of a club has integrally a head body 4 and a hosel 5 to which one end of a shaft is mounted. The head body 4 has a face 3 as the side to strike a ball. In this case, the face 3 is made from a material whose angle of contact with water is 70 to 120 (dgb) and Vickers hardness is 100 to 200 (HV 20), and a ball hitting portion 3a being exposed from the face 3, the 10-point average roughness of which is 1 to 20 (μm) is provided. Thus, by improving the affinity between the ball hitting portion 3a and a golf ball and making them contact in a high friction state, the amount of a backspin of the ball is optimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron golf club and an iron golf club set capable of optimizing the amount of back spin of a hit ball by controlling the surface condition of the face surface of a club head.

[0002]

2. Description of the Related Art General golfers tend to attach importance to flight distance performance in long irons and middle irons having a small loft angle. In order to increase the flight distance of the ball, the repulsion efficiency between the club and the ball is increased, and when the launch angle of the ball is large to some extent, the initial backspin amount of the ball (hereinafter simply referred to as the backspin amount or spin amount) Is effective.)

On the other hand, short irons having a large loft angle often aim directly at the green, so that the ball does not roll but rather rolls after falling (hereinafter simply referred to as "run"). It is desired to reduce it. In order to reduce the run of the hit ball, it is effective to increase the backspin amount of the hit ball.

[0004] Such a backspin amount largely depends on the material and surface condition of the face surface of the golf club with which the ball comes into contact at the time of impact. Conventionally, in order to perform this kind of spin control, for example, it has been proposed to change the friction coefficient of the face surface according to the iron number. For example, JP-A-5-329232 and JP-A-6-329.
Japanese Patent Publication No. 296713 proposes to use carbon for a long iron, iron or stainless steel for a middle iron, and copper for a short iron for a face material of a head.

The present invention was devised as a result of further research, and is based on improving the material of a ball hitting portion provided on the face surface, etc., to optimize the amount of back spin of the club. It is an object of the present invention to provide a golf club and an iron golf club set.

[0006]

According to the first aspect of the present invention, the face surface has a contact angle θ of 70 to 1 with water.
20 (deg) and Vickers hardness of 100 to 200
(HV20) material, and the surface has a ten-point average roughness R
An iron golf club including a ball hitting portion in which z is 1 to 20 (μm).

Here, the contact angle θ with water is shown in FIG.
As shown in (A) and (B), water (pure water) is dropped in small particles on a surface of a horizontally held sample a using a glass tube or the like. The angle formed with the surface of a. This contact angle θ can be measured using, for example, a contact angle measuring device M as shown in FIG. The contact angle measuring device M is capable of moving up and down and placing a sample on an upper surface, and a glass tube d is positioned and held on a surface of a sample a placed on the sample stage c. A stand e and a tube f having one end connected to the glass capillary d
, And an imaging device h such as a CCD equipped with a 50 × lens, for example. In this example, a video adapter j is connected to the imaging device h, and a video signal is sent to a monitor k, a video deck j, and the like.

The measurement of the contact angle θ can be performed according to the following procedure. First, the surface of the sample a is cleaned by wiping with toluene, and is fixed on the horizontally adjusted sample stage c. In order to properly evaluate the contact angle of the sample with water, the ten-point average roughness Rz of the surface is unified to 0.5 μm. The position of the imaging device h is adjusted in advance so that the sample a and the droplet b on the surface thereof are projected on the monitor k. Then, the micro syringe g is operated to form a droplet b of pure water on the surface of the sample a. At this time, the position and the like of the sample stage c are adjusted so that the glass tube d is at the center of the droplet b. After gradually increasing the size of the droplet b (the range of the diameter R of the contact surface of the droplet R <2.0 mm), this image is recorded by the video deck j.

Next, using a micro video scaler or the like, the diameter R and the height H of the contact surface between the sample a and the droplet b are read from the reproduced image of the video deck j, and the following formula (1) is obtained. From (2), the contact angle θ (deg) can be obtained by calculation. When θ ≦ 90 (deg) (FIG. 4 (A)), θ = 2 × tan ⁻¹ (2H / R) (1) When θ> 90 (deg) (FIG. 4 (B)), θ = 90 + cos ^-1 [R · H / {(H ² + (R / 2) ² )}] (2)

Further, in this embodiment, the droplet b is represented by
While the diameter R is increased within a range of less than 2 mm, the R and H are measured three times each, and the average value of contact angles obtained from the diameter R and the height H at each measurement (denoted as θa) )). The angle θa obtained in this manner was defined as the contact angle with water.

The Vickers hardness is JIS Z2
244 "Vickers hardness test method"
The hardness is a hardness obtained by using a diamond square quadrangular pyramid indenter having a facing angle of 136 ° and a test load when a recess is formed on a test surface and a surface area of the recess. Here, assuming that the test load is F (N) and the surface area of the depression is S (mm ² ), the Vickers hardness HV is calculated from the following equation (3). The test load of Vickers hardness referred to in this specification is 196.1.
(N), corresponding to the hardness symbol HV20. Further, in order to properly evaluate the Vickers hardness unique to the sample, a hardness test is performed by unifying the ten-point average roughness Rz of the surface to 0.5 μm. HV = 0.102 × F / S (3)

[0012] The ten-point average roughness is JIS B06.
It is assumed that the measurement is performed in accordance with “Definition and display of ten-point average roughness (Rz)” in the fifth section of No. 01.

According to a second aspect of the present invention, a golf club having the lowest loft angle (i = 1) has the lowest loft angle.
An iron golf club set including a plurality of golf clubs up to the golf club having the highest loft angle (i = q), wherein all of the golf clubs are in contact with water on the face surface. Angle θ is 70 to 120 (de
g) and a material having a Vickers hardness of 100 to 200 (HV20) and a ten-point average roughness Rz of the surface of 1 to 2
It is characterized by including a ball hitting portion of 0 (μm).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings, taking an iron golf club set as an example. As shown in FIG. 1, the iron golf club set 1 of the present embodiment has the lowest loft angle α and the highest count (i = 1) from the golf club 2 a with the highest loft angle α. i = q = 5) golf club 2e
Up to a total number of five. Here, the number “i” is a natural number that is assigned in order from the lowest golf club 2 a to identify each golf club 2, and is the actual number of clubs (for example, a 5 iron number). "5"). FIG. 1 shows the loft angle α of each golf club 2.

Such an iron golf club set 1
Are, for example, a half set consisting of only odd numbers or even numbers, or a seven-piece set of 3 irons to 9 irons (i = 1 to 7). Furthermore, driving irons, 2 irons, pitching wedges , An approach wedge, a sand wedge, a lob wedge, or the like. And the total number of sets is 3 or more, preferably 6 or more, and more preferably 7 or more.
More preferably, the number is preferably 9 to 11, and it is not limited to the combination of FIG.
Further, in the iron golf club set 1, for example, it is preferable that the smallest loft angle is about 10 to 25 degrees and the largest loft angle is about 56 to 60 degrees. Further, the length of the shaft S of each golf club and the like can be gradually shortened with an increase in the loft angle according to a custom.

Each of the golf clubs 2 has a head H. As shown in an enlarged manner in FIG. 2, the head H integrally includes, for example, a head body 4 and a hosel 5 to which one end of a shaft S is mounted. In the present embodiment, the head body 4 has a face surface 3 which is a surface on which a ball is hit. In the present embodiment, all the golf clubs 2a
To 2e, the face surface 3 has a contact angle θ with water of 70
~ 120 (deg) and Vickers hardness is 100 ~ 20
0 (HV20) material with a ten-point average roughness of 1 to
An example including a ball hitting portion 3a exposed on the face surface 3 of 20 (μm) is illustrated.

Here, the contact angle θ with water is generally used as a method for evaluating the “wettability” of the surface of a certain member. It can be said that the larger the contact angle θ is, the less the material is wetted by water. The present inventors have found that, when two objects having surfaces with similar wettability within a certain range are brought into contact with each other, the affinity between them is improved and an excellent high friction state can be obtained. Then, based on such knowledge, the inventors tried to improve the affinity between the ball hitting portion 3a of the face surface 3 and the golf ball in order to create a high frictional contact state.

First, when various contact angles with water were examined for various representative cover materials covering the surface of the golf ball, they were found to be approximately 75 to 90 (deg). In addition, when the contact angles with water of various materials used for the head of the conventional general iron golf club were examined, it was found that the angle was 35 (deg) or more and 70 (deg) or more.
It was found that the value was set to less than the value, which was lower than the wettability of the golf ball. The inventors prototyped a head using various materials and performed experiments by changing the contact angle of the ball hitting portion 3a with water, and found that the contact angle θ with water has a larger value than before. Materials, among others
By using a material having a contact angle θ with water of 70 to 120 (deg), more preferably 75 to 115 (deg), the affinity between the ball hitting portion 3a and the cover material of the golf ball is improved. It has been found that the friction coefficient between objects can be increased. In an iron golf club set having such a ball hitting portion 3a, a back iron is easily applied to a back spin with a short iron, controllability is improved, and, for example, the loft angle is 4
It was confirmed that with a middle iron or a long iron of less than 0 °, the backspin of the hit ball is hardly applied and the flight distance can be improved.

Here, when the contact angle θ with water exceeds 120 (deg) in the ball hitting portion 3a, the reverse of the above-mentioned case is attained. In addition, with a middle or long iron, the backspin of the hit ball tends to be applied, and the flying distance tends to be lost. The reason for such a phenomenon will be described later.

In addition, the material constituting the ball hitting portion 3a needs to have a Vickers hardness of 100 to 200 (HV20). Various conventional iron golf club heads have a ball hitting portion 3a having a Vickers hardness exceeding 300 (HV20). However, according to experiments by the inventors, when the Vickers hardness (surface hardness) of the ball hitting portion 3a is reduced, the true contact area when the ball hitting portion 3a and the golf ball are in contact increases. It was found that the coefficient of friction was large. Accordingly, the material of the ball hitting portion 3a has a Vickers hardness of 100 to 200 (HV20), more preferably 1 to 200.
By setting the value to 20 to 180 (HV20), the coefficient of friction between the ball hitting portion 3a and the golf ball can be further increased while maintaining the minimum surface hardness required for the ball hitting portion. Back spin control performance can be further enhanced. Ball hitting part 3
If the Vickers hardness is less than 100 (HV20), the ball hitting portion 3a is liable to be scratched and a stable spin characteristic tends not to be obtained for a long period. The effect of increasing the coefficient tends to decrease.

As described above, any material can be used for the ball hitting portion 3a as long as the contact angle θ with water is 70 to 120 (deg) and the Vickers hardness is 100 to 200 (HV20). For example, various alloys satisfying these conditions, such as aluminum alloys, copper alloys, and other alloys, can be used.

The ball hitting portion 3a is made of a material that satisfies the above-mentioned conditions, thereby improving the affinity with the cover material of the golf ball and obtaining a high friction state.
It has been found that a more favorable high friction state can be obtained by regulating the surface roughness of the ball hitting portion 3a made of such a material within a certain range. That is, the ball hitting portion 9a has a ten-point average roughness Rz of 1 to
It is desirable that the thickness be 20 (μm), more preferably 3 to 18 (μm). In general, the contact between the golf ball and the ball hitting portion 3a is such that, when the two surfaces are microscopically captured in the friction process, the projections on the two surfaces mesh with each other and climb, slip, scratch, or are crushed, It forms a so-called sliding friction state that sticks or separates. Therefore, as the surface roughness of the ball hitting portion 3a becomes rough, the friction coefficient between the two objects increases.

Therefore, the golf club of the present embodiment regulates the surface roughness (ten-point average roughness Rz) of the surface of the ball hitting portion 3a as described above, so that the distance between the ball hitting portion 3a and the golf ball is reduced. Can be further increased, and the backspin control performance as described above can be further enhanced. Here, if the ten-point average roughness Rz of the ball hitting portion 3a exceeds 20 (μm), it is not preferable because the golf ball is easily damaged. The ten-point average roughness Rz can be variously adjusted by, for example, performing a surface treatment in which abrasive grains having a predetermined particle diameter collide with the ball hitting portion 3a.

As described above, the iron golf club or set of the present invention focuses on the unique surface characteristics (contact angle θ with water, Vickers hardness) of the material constituting the ball hitting portion 3a of the head H, and uses the material. By controlling the surface roughness of the golf ball 2 to be within a certain range, the golf ball 2 having a large loft angle increases the backspin of the hit ball, thereby improving the controllability. Is reduced, which helps to increase the flight distance by preventing the air from rising.

The ball hitting portion 3a of this embodiment is formed as a region sandwiched between vertical lines L1, L2 extending vertically on the toe side and the heel side of the face surface 3. In the ball hitting surface 3a, for example, concave portions such as a plurality of grooves, such as a score line 6 and a punch mark (not shown), may be appropriately formed according to a customary manner, or may be omitted. When the ball hitting portion 3a is made of a material capable of forming a high friction state as described above, for example, only the ball hitting portion 3a is made of the above-described material, and the toe portion, the heel portion, and the like of the face surface 3 are separately provided. In addition to the case where the head H is formed of a material, the entire head H may be formed integrally with the above-described material. In particular, the latter case is preferable in that the production becomes easy.

By the way, conventionally, in the iron golf club 2, it has been considered that the backspin amount of the hit ball increases as the friction coefficient of the ball hitting portion 3a of the face surface 3 increases irrespective of the iron number. That is, when the backspin amount of the hit ball is to be reduced, the friction coefficient of the ball hitting portion 3a is reduced, and when the backspin amount is to be increased, the friction coefficient of the ball hitting portion 3a is increased. there were.

However, as a result of various experiments by the present inventors, for example, for an iron golf club having a loft angle of 40 ° or more, when the friction coefficient of the ball hitting portion 3a is increased, the initial spin amount of the hit ball is certainly increased. But
For iron golf clubs having a loft angle of less than 40 °, it has been found that as the friction coefficient is reduced, the backspin amount of the ball tends to increase slightly, contrary to the conventional expectation.

FIG. 5 shows the relationship between the surface state of the face surface of the club head and the backspin amount of the hit ball in the experimental results. 6 to 9 show the relationship between the surface state of the face surface and the launch angle of a hit ball.

In this experiment, 3 irons (loft angle 21 °), 5 irons (loft angle 29 °), and 7 irons (loft angle 37) were selected from the iron golf club set.
°) and a sand wedge (loft angle: 56 °), and the same ball (two-piece ball) is hit by a swing robot under the same conditions using a swing robot. The initial spin amount (back spin) of the hit ball at that time Amount) and launch angle were measured. The face of each iron is made of titanium, but has no grooves and a smooth surface (smooth).
h) (the one having the lowest coefficient of friction), the one having no grooves and having a rough surface (rough), and the one having grooves and having a rough surface (rough) (the one having the highest coefficient of friction) The comparison was performed with the surface condition of.

According to the results of these experiments, in the case of the # 3, # 5 and # 7 irons having a small loft angle, contrary to the conventional expectation, the larger the friction coefficient of the face is, the smaller the back spin amount of the hit ball is. The tendency that the launch angle was increased was confirmed.

To theoretically and completely elucidate such a phenomenon, a detailed analysis of the complicated deformation behavior of the ball at the time of impact is further required. It can be guessed that the internal spin of the core portion of the ball generated at the time of impact has an influence.

FIGS. 10A to 10D show the state of impact of the ball in time series. FIG. 11 is a graph showing the relationship between the shearing force between the core portion B1 (position P1) of the ball B and the cover B2 (position P2) and the elapsed time from the impact.

As shown in FIG. 10A, the impacted ball B is deformed and adheres to the face surface 3 in a relatively wide area. At this time, the ball B moves from the face 3
It receives a frictional force M in a direction along the face surface 3 and a vertical force from the face surface 3. Conventionally, attention has been paid to only the frictional force M, and it has been considered that the backspin amount of the ball B increases as the frictional force M increases. The inventors examined the process during the impact of the ball B in more detail. As a result, the cover B2 of the ball B was moved by the shear force pulling the cover B2 in the direction of the frictional force. It was determined that the gap was relatively displaced in the circumferential direction (FIG. 10B).

Such a displacement between the core portion B1 and the cover B2 tends to return as the deformation of the impacted ball B starts restoring to the original state. Due to this restoring force, a shear force in the opposite direction acts between the core portion B1 and the cover B2, and the positions P1 and P2 are shifted to the neutral position where the displacement has been eliminated (FIG. 10C). From the face surface 3 at a position that exceeds the threshold value. Immediately before this launch (FIG. 10D), the core portion B1
, There remains a forward internal spin opposite to the back spin, and the more the internal spin, the lower the backspin amount of the ball.

Further, it has been found that such an effect of the internal spin becomes remarkable especially in an iron golf club having a loft angle of, for example, less than 40 °. Therefore, in the iron golf club set of the present embodiment, the ball hitting portion 3a comes into contact with the golf ball in a high friction state, so that in a so-called short iron, the back spin amount of the hit ball increases, the run is reduced, and the controllability is improved. With a middle or long iron having a loft angle of less than 40 °, the backspin amount of the hit ball is relatively reduced. Therefore, when the launch angle is sufficiently large, the flight distance of the hit ball can be greatly improved.

The embodiments of the present invention have been described in detail above. For example, in the case of an iron golf club set, it is sufficient that the ball hitting portion 3a of each club is within the range of each of the above specified values. Club hitting part 3
a is preferably formed of the same material, and more preferably, the ball hitting portions 3a of all clubs are formed of the same material and have the same specifications from the viewpoint of productivity. In the above embodiment, the ball hitting portion 3a
Has been described as an example in which the surface is not coated with plating or the like, but various thin film coatings or the like may be applied. In this case, the contact angle with water and the ten-point average roughness were measured on the coating surface, and the Vickers hardness was measured on the coating surface. The test load F is set so as to be / 10.

[0037]

EXAMPLES Each head of an iron golf club set having a total of five iron golf club sets was experimentally produced using the materials shown in Table 1 (Examples 1 to 5 and Comparative Examples 1 to 5). A golf club was manufactured by attaching a shaft to these heads, and a test hit test was performed by a swing robot to measure the back spin amount of the hit ball. In the head of Example 5, the copper alloy plate was coated with PTEF resin (polytetrafluoroethylene resin). For the head of Comparative Example 4, Ti-N was ion-plated on a stainless steel plate.

In the test hitting test, a two-piece ball "DDH Tour Special RB" manufactured by Sumitomo Rubber Industries, Ltd. using an ionomer resin as a cover material (contact angle of water of the cover material with 93 deg) was used. Table 1 shows the specifications of each head, and Tables 2 and 3 show the chemical compositions of these materials.
Table 4 shows the results of the test hit test.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

As a result of the test, for example, when the contact angle θ with water is 1
In Comparative Example 4 of the material exceeding 20 (deg) and in Comparative Example 2 in which the contact angle θ with water was less than 70 (deg), the back iron was low in the short iron, and the back spin was high in the middle to long iron. You can see that it has become. On the other hand, in the iron golf club set of the present embodiment, it can be confirmed that the golf ball having a small loft angle has a smaller amount of back spin of the hit ball than the iron golf club set of the comparative example. This helps to increase the flight distance. Further, it can be seen that in the iron golf club having a large loft angle, the backspin amount is increased and the controllability is improved.

[0044]

As described above, in the iron golf club of the present invention, the face surface has a contact angle θ of 70 to 1 with water.
20 (deg) and Vickers hardness of 100 to 200
(HV20) material, and the surface has a ten-point average roughness R
By including the ball hitting portion having z of 1 to 20 (μm), the affinity with the golf ball is improved, and the golf ball comes into contact with the golf ball in a high friction state, so that the back spin amount of the hit ball can be optimized.
Specifically, a middle or long iron having such a ball hitting portion helps to reduce the backspin amount of the hit ball to increase the flight distance, and a short iron with a large loft angle increases the backspin amount to control. Performance can be improved.

According to the second aspect of the present invention, all the golf clubs of the iron golf club set include the above-described ball hitting portion on the face surface, so that the back spin amount of the hit ball is reduced in the middle or long iron. In addition to helping to increase the flight distance, a short iron having a large loft angle can provide an excellent set of golf clubs that can increase the backspin amount and improve controllability.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of an iron golf club set according to an embodiment.

FIG. 2 is a front view illustrating a part of a golf club taken out of the set of the embodiment and illustrating the golf club;

FIG. 3 is an explanatory diagram illustrating a method for measuring a contact angle with water using a contact angle measuring device M;

FIGS. 4A and 4B are cross-sectional views of a sample for explaining measurement of a contact angle.

FIG. 5 is a graph showing a relationship between a surface state of a face surface and a back spin amount of a ball.

FIG. 6 is a graph showing a relationship between a surface state of a face surface and a launch angle of a hit ball.

FIG. 7 is a graph showing a relationship between a surface state of a face surface and a launch angle of a hit ball.

FIG. 8 is a graph showing a relationship between a surface state of a face surface and a launch angle of a hit ball.

FIG. 9 is a graph showing a relationship between a surface state of a face surface and a launch angle of a hit ball.

FIGS. 10A to 10D are cross-sectional views illustrating a process of impact between a ball and a face surface.

FIG. 11 is a graph showing the relationship between the time elapsed from impact and the shearing force between the ball cover and the core portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron golf club set 2 Golf club 3 Face surface 3a Ball hitting part S shaft H Club head

Claims (2)

[Claims] 1. The face surface has a contact angle θ of 70 to 1 with water.
20 (deg) and Vickers hardness of 100 to 200
(HV20) material, and the surface has a ten-point average roughness R
An iron golf club, comprising a ball hitting portion wherein z is 1 to 20 (μm). 2. The lowest count (i = lowest loft angle)
An iron golf club set including a plurality of golf clubs from the golf club of 1) to a golf club having the largest loft angle (i = q), wherein all the golf clubs have a face. The surface has a contact angle θ with water of 70 to 120 (deg) and a Vickers hardness of 1
An iron golf club set comprising a ball striking portion made of a material of 00 to 200 (HV20) and having a ten-point average roughness Rz of 1 to 20 (μm) on the surface.