JPH10286334A - Golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of back spins and improve the ball control by setting a dynamic frictional factor between a ball and the face surface at a specified value. SOLUTION: A dynamic frictional factor μb between a ball and the face surface 20 of a club head 2 is measured by using a cover 10 which is peeled from the golf ball as an indentator. That is, under a low load N1, the cover 10 is pressed to the face surface 20 at an area which is away from a score line. The cover 10 is moved at a speed of approx. 150 mm/min in parallel with the score line, and a horizontal force F1 which is required for the moving is measured, and F1/N1 is obtained as the dynamic frictional factor μb. This value is set at 0.10-0.23. By this constitution, the number of back spins can be increased, and the ball controllability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a golf club head.

[0002]

2. Description of the Related Art In recent years, two-piece balls have become the mainstream of golf balls instead of wound balls. Two-pisce balls have a smaller number of backspins than thread-wound balls, so that the ball is less likely to stop after landing (after dropping). In clubs aiming for distances such as drivers and long irons, although the rolling (run) after landing is extended, factors influenced by the environment such as obstacles and terrain are large,
There is a problem that the ball does not stop at the target location. On the other hand, in the case of a middle iron or a short iron, it is highly necessary to stop at a place where the ball is aimed. Therefore, it is desired to increase the number of spins so that rolling after landing is reduced.

[0003]

In a golf club head, an angle called a loft angle is provided on a face portion in order to positively increase the number of back spins. In addition, the face is modified to adjust the number of spins. In this example, the surface roughness is adjusted between golf club sets to adjust the spin rate between sets, or a resin plate, a metal plating film, a coating film, or the like is provided on the face surface, and the spin rate is adjusted. Has been made to control.

An object of the present invention is to improve ball control by improving the face surface of a golf club head to increase the number of back spins.

[0005]

Prior to the description of the structure of the present invention, the principle of the present invention will be described. As shown in FIG. 1A, at the time of hitting, a force (vertical force) N in a direction perpendicular to the face surface 20 of the head 2 and a horizontal force (horizontal force) F along the face surface 20 are applied to the ball. Join 1 FIG. 2 shows the results of measuring the temporal changes of these forces N and F.
(A) and (b) show. As can be seen from FIG.
The vertical force N starts to be applied to the ball 1 from the initial stage of contact, and the vertical force N becomes maximum at the time point t1 when the deformation becomes almost maximum. Thereafter, when the vertical force N decreases and eventually becomes zero, the ball 1 jumps away from the face surface 20. The horizontal force F shown in FIG. 1A is a factor that causes the back spin Sb to be applied to the ball 1 and acts on the ball 1 as a shearing force. As can be seen from FIG. 2 (b), the horizontal force F increases in the direction in which the backspin Sb is applied at the initial stage of contact, reaches a maximum slightly before the time t1 at which the deformation becomes almost maximum, and thereafter decreases, Before the end of the contact, after slightly acting in the direction of applying the top spin St, it becomes 0,
The ball 1 separates from the face surface 20. As described above, the cause of the top spin St is that the ball 1 collides with the face surface 20 obliquely, as shown in FIG.
It is presumed that this is because the deformation (the hatched portions L and R) of the ball 1 causes an elastic deformation in which the right and left become uneven, and the stress frequency of this elastic deformation is lower than the stress frequency of the elastic deformation with respect to the normal force N.

The number of back spins of the ball 1 is shown in FIG.
Is determined by a value obtained by integrating the horizontal force F with respect to time, and is increased by increasing the integrated value. On the other hand, by sliding the ball 1 in the initial stage of contact, it can be considered that the change in the horizontal force F becomes as shown in FIG.
It is presumed that the horizontal force (shear force) F in the top spin direction at the end of contact can be reduced. That is, it is assumed that the number of back spins can be increased by sliding the ball 1 at the initial stage of contact.

Here, in order to slide the ball 1 in FIG.
It is necessary to reduce the coefficient of dynamic friction μb between the ball 1 and the face surface 20. Therefore, the present invention reverses the conventional theory that the number of back spins can be increased by increasing the friction coefficient. By reducing the dynamic friction coefficient μb between the ball 1 and the face surface 20, the back spin is reduced. It increases the number.

That is, according to the first aspect of the present invention, the loft is 51
° is set below, and a golf club head having a groove in the face surface, having a face surface which the value of the dynamic friction coefficient μb with a golf ball is set to 0.10 to 0.23.

According to a second aspect of the present invention, in a golf club head having a loft set to 51 ° or less and having a groove on a face surface , a value of a dynamic coefficient μs with respect to a stainless steel ball made of SUS304 having a diameter of 10 mm is reduced. It has a face surface set between 0.070 and 0.140 .

A third aspect of the present invention is a golf club head having a loft set to 51 ° or less and having a groove on the face surface , wherein the face surface of the metal plating layer on which the fluorine-containing polymer fine particles are deposited is formed. In addition, the hardness of the face surface is set to 200 Hv to 600 Hv.

[0011] In the invention of claim 4, the loft is set at 51 ° or less.
In a golf club head having a fixed iron count and a groove on the face surface, the golf club head has a face surface of a metal plating layer on which fluoropolymer fine particles are deposited. Claim
In the invention of Item 5, the loft is set to 20 ° to 51 °, and
In a golf club head having a groove on a face surface,
The value of the coefficient of kinetic friction μb with the golf ball is 0.10 to 0.281
It has a set face surface. The invention of claim 6 is
The shaft is set at 20 ° to 51 ° and a groove is formed on the face
SUS with a diameter of 10mm
The value of dynamic friction coefficient μs with 304 stainless steel ball is 0.07
It has a face surface set to 0-0.190.

[0012]

Hereinafter, examples, test examples and comparative examples of the present invention will be shown, and the relationship between these results and the scope of the present invention will be described.

First, the specimen used for the test will be described. Golf club head: The golf clubs used for the test were driver, spoon, buffy, 4 iron (4I) to 9 iron (9I), pitching wedge (PW), approach wedge (AW) and sand wedge (SW). is there. The reason for using many types of golf clubs in this way is that the loft differs greatly for each type of club head, and the horizontal force F in FIG. The horizontal force F in FIG. 1A is affected by the angle between the face surface 20 and the moving direction of the head 2 when the face surface 20 contacts the ball 1, so that the face surface 20 and the vertical line Was determined from a large number of subjects, and an actual loft θ was set. As shown in FIG. 3, a club head having a large number of score lines (face lines) 21 was used.

Dynamic friction coefficient μb with the ball: The cover of the golf ball was peeled off, and the cover 10 was used as an indenter as shown in FIG. To reproduce the state close to the initial stage of contact,
The load N1 was set to a low load (100 g). The cover 10 of the ball is pressed against the face surface 20 at a portion off the score line, the cover 10 is moved at a speed of 150 mm / min. In parallel with the score line, and the horizontal force F1 required for the movement is measured.
Was defined as the dynamic friction coefficient μb. As the golf ball, a two-piece ball manufactured by ASICS Corporation was used.

Dynamic friction coefficient μs with stainless steel ball: Golf balls change with the times, and it may be difficult to obtain a cover equivalent to the golf ball cover used in this test in the future. In drawing
A dynamic friction coefficient μs with the stainless steel ball was measured using an objective stainless steel ball (reference material) to define the dynamic friction coefficient. A stainless steel ball having a diameter of 10 mm and made of SUS304 was used. The load N1 was set to 50 g, and F1 / N1 was set to the dynamic friction coefficient μs in the same manner as described above.

As a method of changing the dynamic friction coefficient, as in the case of a normal head, in addition to a method of sandblasting, a mirror-finished method, a face of these heads,
The surface 20 coated with water containing a surfactant, and a nickel plating layer (hereinafter referred to as a “co-fold layer”) on which fine particles of polytetrafluoroethylene (PTFE) are deposited (eutectoid). And the one whose face surface was coated with PTFE (Teflon processing). The co-fold layer had a thickness of about 10 μm to 15 μm. Fine particles of PTFE exist inside and on the surface of the nickel plating layer, and the content (co-folding amount) of the PTFE was changed to change the dynamic friction coefficient μb in small steps. Further, since the dynamic friction coefficient μb changes depending on the surface hardness, some of the test pieces were heat-treated at about 300 ° C. for 2 hours to change the surface hardness. The surface hardness was measured by a Vickers hardness test. The method of forming the co-folded layer is described in paragraph No. 0022 of JP-A-5-228229.
A method similar to the known method described in detail in ００３０-0030 was used.

In the test, an angle θ between the face surface 20 and the vertical line is set as a set loft, and a repulsion experiment is performed in which a non-rotating ball collides against the face surface 20 from a horizontal direction.
An actual hitting experiment in which a plurality of subjects actually hit the ball was performed. In addition, as a method of obtaining the number of back spins, a strobe photographing of a ball that has jumped out of the face surface 20 is performed.
From the change in the position of the mark on the ball, the number of spins was calculated. The launch ball speed V and the launch ball angle α were also calculated. The launch ball speed V and the launch ball angle α in the rebound test are shown in FIG.
As shown in (a) and (b), the coordinates were converted to obtain from the velocity vectors Vin and Vout of the ball before and after the collision.

Examples 1 to 10: A SUS431 head for 7-iron (7I) was provided with a co-fold layer having a co-fold amount of 2.5 wt% to 12 wt%, and the dynamic friction coefficients μb, μs and hardness were measured. , Set the loft to 28.9 ° and conducted a rebound experiment,
The number of back spins was measured. Comparative Examples 1 to 3: The 7th iron (7I) was subjected to sandblasting or mirror finishing, and measured in the same manner as in Examples 1 to 10. Examples 1S, 1M: 7-iron iron used in comparative example
Example 1 was coated with water containing a surfactant on the ground surface.
It measured similarly to 10. Examples 1 to 10 above , Examples
The test results of 1S, 1M and Comparative Examples 1 to 3 are shown in Table 1 and FIG.

[0019]

[Table 1]

[0020] Examples 11 to 20, Comparative Examples 11 to 13, the real
Example 2S, 2M : Except that a SUS431 4-iron (4I) head was used and the set loft was set to 21.2 °,
It measured using the same method as Examples 1-10, Comparative Examples 1-3, Examples 1S and 1M . Table 2 and FIG.
Shown in

[0021]

[Table 2]

[0022] Examples 21 to 30, Comparative Examples 21 to 23, trial
Experimental Example 3S, 3M : The same method as in Examples 1 to 10, Comparative Examples 1 to 3, and Examples 1S and 1M was used, except that the set loft was set to 10.7 ° using a SUS630 driver head. Measured. The results are shown in Table 3 and FIG.

[0023]

[Table 3]

FIG. 6 shows that the backspin number increases by reducing the dynamic friction coefficients μb and μs. In some drivers, the number of back spins decreased, but this was presumed to be due to the large variation in the measurement results of the spin number and the dynamic friction coefficient. Therefore, a driver is also included in the present invention. On the other hand, Japanese Patent Laid-Open No. 5-2
In the invention of Japanese Patent No. 28229, an actual hitting experiment similar to that of the present invention was performed on a driver, and it was reported that a club having a co-folded layer had a lower backspin number.
As described above, the difference between the test result according to the present invention and the test result according to the prior art may be due to the difference in the dynamic friction coefficient μb with the golf ball. That is, FIG.
As can be seen from this test, the dynamic friction coefficient μb with the golf ball was only obtained from 0.123 to 0.281 in this test.
Therefore, the following test was performed to determine the lower limit of the dynamic friction coefficient μb at which the number of back spins increases.

Comparative Examples 24 and 25: A hitting test was carried out on a conventional product sandblasted using a 9-iron head and a Teflon-processed product on which a score line was re-engraved, and then measured. . Table 4 shows the results.

[0026]

[Table 4]

As can be seen from the results of Comparative Examples 24 and 25, when the dynamic friction coefficient μb is too small, the backspin number is greatly reduced. This is the dynamic friction coefficient μ
If b is too small, it is presumed that the slip between the ball and the face surface becomes too large, causing not only an initial slip but also a continuous slip, and the horizontal force F is not sufficiently applied to the ball. You. Further, from the results of Comparative Examples 24 and 25, in the above prior art, the coefficient of dynamic friction μ with the golf ball was
It is presumed that the number of back spins was reduced because b was too small and only the driver was tested. Therefore, it is estimated from Tables 1 to 4 that the coefficient of dynamic friction μb with the golf ball is preferably set to 0.10 or more. The coefficient of dynamic friction μs with the stainless steel ball is 0.0
To set more than 70 Ru is presumed preferable.

In the above embodiment, the hardness is 264 Hv to 5
Although the backspin number increases for 10 Hv, the hardness of 700 Hv to 900 Hv is described as decreasing the backspin number in the invention of JP-A-5-228229. 200Hv ~ 600
It is presumed that Hv is preferable.

Next, in order to examine the relationship between the set loft and the number of back spins, the number of back spins was measured while changing the set loft. Examples 31 to 40, Test Example 41: A co-fold layer having a co-fold amount of 9 wt% was applied to various club heads, and a rebound test was performed by changing the set loft, and the number of back spins was measured. Table 5 shows the results.

[0030]

[Table 5]

Comparative Examples 31 to 41: Various club heads were subjected to sand blast, and a rebound test was performed while changing the set loft to measure the number of back spins. The results are shown in Table 5 above.

Except for the sand wedge having a large loft and a large loft, the backspin number increased in all cases. The reason for the decrease in the number of back spins in the sand wedge is that the sand wedge has a large set loft,
Even if the dynamic friction coefficient μb is not reduced, the initial slip occurs. It is presumed that if the dynamic friction coefficient μb is reduced, not only the initial slip but also the continuous slip occurs.
Therefore, the present invention is applied to a head having a loft angle of 51.0 ° or less. Next, loft, dynamic friction coefficient
The relationship between the upper limit of μb and μs and the number of back spins
To consider. First, the dry loft in Table 3 with the smallest loft
When we examine the bars, we can see from the results in Table 3.
In addition, the coefficient of dynamic friction μb with the golf ball is 0.230 or less.
Since the number of spins has increased on average,
Even if the loft is small, the coefficient of dynamic friction μb with the golf ball is
0.230 or less or dynamic friction coefficient μs with reference object is 0.140 or less
If it is below, it is included in the present invention. In addition, based on the results in Table 5,
As you can see, the larger the loft, the more backspin
Head is more than 13 °
Then, the coefficient of dynamic friction μb with the ball is 0.10 to 0.23, or
Has a dynamic friction coefficient μs of 0.070 to 0.140
However, a sufficient effect can be expected. In addition, Table 1 to Table 5
As can be seen, irons with larger lofts
Since the increase in the number of pins has become even more pronounced,
For heads with a loft between 20 ° and 51 °, the dynamic friction
Several μb is 0.10 to 0.281 or the movement with stainless steel ball
A sufficient effect is expected even if the friction coefficient μs is 0.070 to 0.190.
Wear. If the loft is between 13 ° and 51 °,
More preferably, the dynamic friction coefficient μb is set to 0.10 to 0.22.
More preferably, it is set to 0.11 to 0.20. Also,
Set the coefficient of dynamic friction μs with the stainless steel ball to 0.80 to 0.150.
More preferably.

As can be seen from FIG. 6 and Tables 1 to 3, the iron has a more remarkable effect than the driver. This is presumed to be due to the fact that the driver has a small set loft and therefore has a large deformation of the ball, which requires a complicated analysis as a viscoelastic body. Therefore, the present invention is preferably applied to iron clubs. In the invention of Japanese Patent Application Laid-Open No. 5-228229, an experiment was conducted only with respect to a driver. On the other hand, as for irons, as can be seen from FIG. Even if it is hard (even at 700 Hv or more), it is estimated that the backspin number increases.

In the present invention, as a method of reducing the dynamic friction coefficient, a co-folded layer of fluoropolymer fine particles including the above-mentioned PTFE co-folded layer is preferable. Here, the nickel plating is performed by electroless plating, but may be nickel alloy plating containing a metal other than nickel or the like, or may be a co-folded layer of another metal and PTFE. Further, polymer fine particles such as boron-based materials other than fluorine-based materials and polyethylene (PE) may be co-folded in the metal plating layer. Also, MoS
₂ (molybdenum disulfide), WS ₂ (tungsten disulfide),
BN (boron nitride), Graphite (graphite), phthalocya
nine (phthalocyanine), (CFx) n (fluorocarbon), W
Se ₂ (tungsten selenide), NaCro ₂ (sodium chromate)
Layered components such as thorium, PbO (lead oxide), PbS
(Lead sulfide), PbI ₂ (lead iodide), CdI ₂ (cadmium iodide)
), AgI (silver iodide), NaF (sodium fluoride),
Soft metal compounds such as CaF ₂ (calcium fluoride), In
(Indium), Pb (lead), Ag (silver), Au (gold)
Soft metals such as Ca (calcium), Na (Natori)
), Mg (magnesium), Al (aluminum)
Which metal soap, etc. is blended into the metal as a solid lubricant
Or may be attached to the surface. Furthermore ,
The coating may be applied to the surface or the metal may be impregnated with oil to reduce the dynamic friction coefficient.

[0035]

As described above, according to the present invention, the kinetic friction coefficient μb
Is set, the deformation of the golf ball, which is a viscoelastic body, which causes top spin is reduced by the initial slip, and the number of back spins is increased. Therefore, ball control becomes easy.

[0036]

[History of the application] This application focuses on the so-called domestic priority.
Application that has been newly added or deleted.
About it, it is underlined.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state of collision between a head and a ball.

FIG. 2 is a diagram showing changes in vertical force and horizontal force at the time of impact.

FIG. 3 is a front view of a club head.

FIG. 4 is a conceptual diagram showing a method for measuring a dynamic friction coefficient.

FIG. 5 is a conceptual diagram showing a method of calculating a launch ball speed and a launch ball angle.

FIG. 6 is a graph showing the relationship between the coefficient of dynamic friction and the number of back spins.

[Explanation of symbols]

 1: ball 2: head 20: face surface F: horizontal force N: vertical force

Claims (6)

[Claims] 1. A loft is set to 51 ° or less, and a golf club head having a groove in the face surface, a golf club which the value of dynamic friction coefficient μb with a golf ball having a face surface that is set to 0.10 to 0.23 head. 2. A golf club head having a loft of 51 ° or less and a groove on a face surface , wherein a value of a coefficient of dynamic friction μs with a stainless steel ball made of SUS304 having a diameter of 10 mm is set to 0.070 to 0.140. Golf club head having a curved face surface. 3. A golf club head having a loft set at 51 ° or less and a groove on a face surface , wherein the golf club head has a face surface of a metal plating layer on which fluorine-based polymer fine particles are deposited. Surface hardness is 200Hv ~ 6
Golf club head set to 00Hv. 4. A golf club head having a loft set to 51 ° or less, an iron count and a groove on the face surface, wherein the golf club has a face surface of a metal plating layer on which fluoropolymer fine particles are deposited. head. 5. The loft is set at 20 ° to 51 °, and
In a golf club head having a groove on a face surface,
The value of the coefficient of kinetic friction μb with the golf ball is 0.10 to 0.281
A golf club head having a set face surface. 6. The loft is set at 20 ° to 51 °, and
In a golf club head having a groove on a face surface,
Dynamic friction with a stainless steel ball made of SUS304 with a diameter of 10mm
A face with a value of several μs set between 0.070 and 0.190
Golf club head.