JP2000296193A - Iron golf club and iron golf club set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize spin quantity of a hitting ball, and increase a carry by arranging a recess/projection hitting surface having an average inclination and a square average inclination being respectively a specific angle on a face surface of an iron golf club. SOLUTION: An iron golf club set 1 has sets up to a high No. (i=q=6) golf club 2e having a maximum loft angle α from a low No. (i=1) golf club 2a having a minimum loft angle α. Here, the respective golf clubs 2a to 2e are formed so as to have a recess/projection hitting surface 3a having an average inclination of 0.15 to 0.25 (deg) and a square average inclination of 0.20 to 0.30 (deg) in a hitting area T of a face surface 3. Thus, in the golf clubs 2a to 2c having a loft angle less than 40 deg., initial spin quantity of a hitting ball is reduced to increase a carry of the hitting ball. While, in the golf clubs 2d, 2e having a loft angle not less than 40 deg., a run is reduced by increasing the initial spin quantity of the hitting ball to improve controllability of the hitting ball.

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 a spin rate of a hit ball by controlling a surface condition of a face surface of a club head.

[0002]

2. Description of the Related Art General golfers tend to attach importance to flight distance performance with long irons having a small loft angle. In a long iron, in order to increase the flight distance of the ball, in addition to increasing the rebound efficiency between the club and the ball, when the launch angle of the ball is large to some extent, the initial spin amount (initial back spin amount) of the ball is increased. It is effective to reduce it. On the other hand, in the case of a short iron such as a wedge having a large loft angle, it is desired that the rolling after the ball falls, that is, the so-called “run”, is reduced rather than the flight distance.
In order to reduce such a run, it is effective to increase the initial spin amount of the hit ball.

[0003] The amount of spin of such a hit ball largely depends on the surface condition of the face surface of the golf club with which the ball contacts at the time of impact. Conventionally, it has been considered that the backspin amount of a hit ball increases as the friction coefficient of the face surface increases irrespective of the iron golf club number. JP-A-272067, JP-A-2-228980
Gazette, JP-A-2-228811, JP-A-9-19-1
No. 92274 has been proposed.

That is, in these conventional proposals, when the initial spin amount of a hit ball is to be reduced, the friction coefficient of the face surface is reduced, and when the initial spin amount is to be increased, the friction coefficient of the face surface is reduced. By increasing the size, the spin performance is controlled.

[0005]

However, as a result of various experiments conducted by the present inventors, for example, in the case of an iron golf club having a loft angle of 40 ° or more, when the friction coefficient of the face surface is increased, it is certain that the initial stage of the hit ball Although the spin rate increases, for iron golf clubs having a loft angle of less than 40 °, the backspin rate of the ball slightly increases as the friction coefficient of the face surface decreases, contrary to the conventional expectation. Turned out to be prone.

FIG. 6 shows the relationship between the surface condition of the face surface of the club head and the backspin amount of the hit ball in the experimental results. 7 to 10 show the relationship between the surface condition of the face surface and the launch angle of the hit ball.

In this experiment, a third iron (a loft angle of 21 °), a fifth iron (a loft angle of 29 °), and a seventh iron (a loft angle of 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.

[0008] As a result of these experiments, in No. 3, 5 and 7 irons having a loft angle of less than 40 °, the backspin amount of the hit ball increases as the friction coefficient of the face increases, contrary to the conventional expectation. It was confirmed that there was little tendency to increase the launch angle.

To completely elucidate such a phenomenon theoretically, a detailed analysis of the complicated deformation behavior of the ball at the time of impact is further required. One of the causes is that the face of the club head, the ball, 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. 11 (a) to 11 (d) show the state of impact of the ball in chronological order. FIG. 12 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. 11A, 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, and found that the cover B2 of the ball B
Has found that the positions P1 and P2 inside the ball shown in the figure are relatively displaced in the circumferential direction by the shearing force pulling the cover B2 in the frictional force direction (FIG. 1).
1 (b)).

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 shearing 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. 11C). From the face surface 3 at a position that exceeds the threshold value.

Immediately before this launch (FIG. 11D), a forward internal spin in a direction opposite to the back spin remains in the core portion B1. It turned out that the backspin amount of the ball was reduced.

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 °. Accordingly, in such an iron golf club, when the coefficient of friction of the face surface is reduced, the internal spin of the core portion B1 rotating in the forward direction decreases, so that the backspin amount of the ball tends to increase. That is, if the friction coefficient of the face surface is reduced in order to reduce the backspin of a hit ball in a long iron, for example, based on the conventional knowledge, the backspin actually increases, so that an improvement in flight distance performance cannot be expected.

Therefore, in order to improve the flight distance performance in a so-called long iron, it is desirable to suppress the initial spin amount of a hit ball by increasing the friction coefficient of the face surface, contrary to the conventional technique. It has been found that it is better to increase the initial spin rate of the hit ball by increasing the friction coefficient of the face surface in order to reduce the friction coefficient.

In order to increase the friction coefficient of the face surface, it is conceivable to roughen the face surface (increase the surface irregularities). As a method for specifying the surface roughness of an object, for example, “ten-point average roughness”, “maximum height”, and the like defined in JIS B0601 and the like are known. However, since such parameters merely specify the heights (vertical distances) of peaks and valleys that form irregularities on the surface of the object, the specific slopes of the peaks and valleys that form irregularities, that is, the slopes of the slopes, I cannot know at all about the speed. As a result of conducting various experiments, the inventors have limited the average inclination angle θa indicating the average inclination angle of the peaks and valleys forming the fine irregularities on the face surface and the root mean square inclination angle θq to certain ranges. It was found that the optimum initial spin amount of the hit ball can be obtained.

As described above, an object of the present invention is to provide an iron golf club capable of optimizing a spin rate of a hit ball on the basis of regulating fine irregularities on a face surface. Another object of the present invention is to provide an iron golf club set capable of exhibiting optimal performance according to the iron number, based on the above-described new knowledge about the initial spin amount and the friction coefficient of the face surface. It is.

[0019]

The iron golf club of the present invention has an average inclination angle θa of 0.15 to 0.15 on the face surface.
0.25 (deg) and the root-mean-square inclination angle θq is 0.
It is characterized by including an uneven hitting surface of 20 to 0.30 (deg).

Here, the “average inclination angle θa” and the “mean-square inclination angle θq” are the peaks of the contour appearing at the cut when cut along a plane substantially perpendicular to the face surface (target surface of the object).
It is correlated with the inclination angle of the valley. In this example, "ISO 42
87 / 1-1984 ". The “average inclination angle θa” and the “mean-square inclination angle θq” according to the present invention are specifically performed as follows.

First, as shown in FIG.
Of the cut surface when cut along a plane perpendicular to the face surface 3 is obtained. Hereinafter, such a contour is referred to as a “cross-sectional curve”. As shown in FIG. 3, such a cross-sectional curve is traced by the stylus V of the stylus type surface roughness measuring device A on the surface of the face surface 3, and the vertical movement displacement of the stylus V is detected by the detecting unit S. It shall be obtained by detecting and recording this.
At this time, either the face surface 3 or the stylus V may be moved, but in this example, the stylus V is moved along the reference guide surface G.

Such a cross-sectional curve is represented as shown in FIG. 4 (A). In the figure, the horizontal direction corresponds to the tracing direction of the stylus V, and the vertical direction corresponds to the vertical movement displacement of the stylus V. are doing. Note that the larger the curvature of the tip of the stylus V (the smaller the radius of curvature), the more accurately the unevenness of the face surface 3 can be traced. However, in the present invention, the tip radius of the stylus V is set to 5 μm, and it is possible to trace with the radius. The short-wavelength component of the non-existent section curve is excluded.

Next, from the cross-sectional curve obtained as shown in FIG. 4A, an average line of the cross-sectional curve is obtained by using the least squares method.
The cross-sectional curve obtained by tilt-correcting the cross-sectional curve using the average line as a correction reference line is shown in FIG.
Obtain on the Z coordinate. Here, the “average line” is a straight line set so that the sum of squares of the deviation up to the cross-sectional curve is minimized. Further, "correcting the average line as a correction reference line" means subtracting the average line from the cross-sectional curve to correct the inclination of the cross-sectional curve itself (in other words, moving the cross-sectional curve so that the average line is located on the X axis). Let it do.)

Next, the corrected sectional curve (Z = f
The average inclination angle Δa (tangent value), which is the average value of the absolute value of the deviation from the center line of the differential curve obtained by differentiating (x)), is calculated by the equation (1).
, And the root mean square angle Δq (tangent value) of a curve obtained by differentiating the corrected cross-sectional curve is obtained by equation (2). The “center line” refers to a straight line that is parallel to the average line and whose area surrounded by the straight line and the differentiated curve is equal on both sides of the straight line.

(Equation 1)

Then, according to the equation (3), the average inclination angle θa
(Deg) and the root mean square angle θq according to equation (4).
(Deg). θa = tan ⁻¹ Δa (3) θq = tan ⁻¹ Δq (4)

In the present specification, such “average slope”,
The “root mean square” was measured using a surface roughness measuring device Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd., with a radius of the tip of the stylus of 5 μm, a driving speed of 0.3 mm / s, and a measurement length of 1.5 mm.
And the measurement is performed by setting the "correction method" as "straight line correction using a straight line obtained by the least squares method as a correction reference line" and setting the "extraction curve" as a "cross-sectional curve" as the device setting value. Was. The reference length L in the expressions (1) and (2) is 1.5 μm in this example, and the measurement points are vertical lines L1 and L, which are substantial hitting portions of the face surface.
Two points were randomly measured between two points and excluding the score line, and the arithmetic average value was used.

The average inclination angle θa and the root mean square angle θq can be used to specify the peaks and valleys of the irregularities which cannot be simply expressed by the maximum height Rmax of the surface irregularities or the ten-point average roughness. it can. For example, as shown in FIGS. 5A and 5B, even if the two surfaces have the same maximum height Rmax of the surface irregularities, the average inclination angle θa and the root mean square inclination angle q are restricted as in the present invention. By doing so, a face surface whose cross-sectional curve is completely different can be formed.

Table 1 shows an average inclination angle θa and a root mean square inclination θq of the face surface of an iron golf club marketed by the applicant company according to the above-described measuring method.
The result of having investigated is shown.

[0029]

[Table 1]

As described above, according to the present invention, the face surface is provided with the uneven hitting surface in which the average inclination θa and the root mean square θq are regulated to be in a range of larger values as compared with the conventional product. The surface can be formed to have a surface roughness including sharp peaks and valleys. This allows the face surface to create a state of high friction with the ball. Such a face surface is useful, for example, in iron golf clubs having a loft angle of 40 ° or more to reduce the run. This is useful for reducing the initial spin amount and increasing the flight distance.

Accordingly, a plurality of golf clubs are set from the lowest number (i = 1) golf club having the smallest loft angle to the highest number (i = q) golf club having the largest loft angle. In the iron golf club set, the average inclination angle θa is 0.15 to 0.25 (deg) and the root mean square angle θq is 0.20 to 0.30 (deg) on the face surfaces of all the golf clubs. By including the uneven hitting surface of (1), it is possible to provide an iron golf club set that can obtain an optimum initial spin amount of a hit ball through all counts.

The irregular hitting surface can be formed by using a shot blasting process in which blast particles containing metal or ceramic particles having a diameter of more than 1.0 mm and not more than 2.0 mm are jetted. .

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking an iron golf club set in which a plurality of iron golf clubs are set as an example. FIG.
As shown in the figure, the iron golf club set 1 of the present embodiment has the smallest loft angle α and the lowest number (i = 1).
The total number of golf clubs from the golf club 2a having the largest loft angle α to the golf club 2e having the highest loft angle (i = q = 6) is set to 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.
Indicates the loft angle α of each golf club 2.

Such an iron golf club set 1
Specifically, for example, a half set in which the number of counts is only an odd number or an even number, a set of 7 pieces from 3rd iron to 9th iron (i = 1 to 7), and a driving iron, One or more pieces such as irons, pitching wedges, approach wedges, sand wedges, and lob wedges can be added. And the total number of sets is 3 or more, preferably 6 or more,
More preferably, it can be composed of 7 or more, more preferably 7 to 10 pieces.

In the iron golf club set 1, for example, the loft angle is the smallest, and
Degree, the loft angle is the largest, and it is preferable to be about 56 to 60 degrees. Each club head H (hereinafter, sometimes simply referred to as head H) is made of stainless steel, titanium,
It can be composed of various materials such as a titanium alloy, soft iron, or a composite material combining two or more of these. Note that the shaft S can be gradually shortened according to a custom, for example, as the loft angle α increases.

As shown in FIG. 2, the head H includes a head body 4 and a hosel 5 on which a shaft S is mounted. In the present embodiment, the head body 4 has vertical lines L1, L2 on the face surface 3, which is the surface on which the ball is hit.
2, the hitting area T for hitting the golf ball substantially
Are exemplified. In the hitting area T, for example, concave portions such as a plurality of grooves, such as a score line 6 and a punch mark (not shown), can be appropriately formed according to a common practice.

In this embodiment, all the golf clubs 2a to 2e have an average inclination angle θa of 0.15 to 0.25 (deg) and a root mean square in the hitting area T of the face surface 3. When the angle θq is 0.20 to 0.30 (de
g) that includes the uneven hitting surface 3a.

In such a golf club set 1, for example, an iron golf club 2 having a loft angle of less than 40 °
In a, 2b, and 2c, the initial spin amount of the hit ball can be relatively reduced based on the above-described knowledge, and the flight distance of the hit ball can be significantly improved when the launch angle is sufficiently large. Further, in the iron golf clubs 2d and 2e having a loft angle of 40 ° or more, the run can be reduced and the controllability of the hit ball can be improved by increasing the initial spin amount of the hit ball.

Here, when the average inclination angle θa of the irregular hitting surface 3a is less than 0.15 (deg) or the root mean square angle θq is less than 0.20 (deg), the peaks and valleys of the irregularities on the surface are reduced. The inclination becomes gentle, making it difficult to create a high frictional contact state at the time of impact with the ball. Conversely, the average inclination angle θa is larger than 0.25 (deg) or the root mean square angle θq is 0.30. (Deg)
There is a problem that the ball is easily damaged when hit with the ball. Particularly preferably, the average inclination angle θa
Is 0.17 to 0.23 (deg), the root mean square angle θq
Is desirably 0.22 to 0.28 (deg).

It is to be noted that the uneven surface 3a preferably has a ten-point average roughness of 10 to 30 μm, more preferably 20 to 30 μm, in addition to the inclination of the unevenness, its depth (amplitude), and the like. Is also particularly preferable in that it can be regulated. The ten-point average roughness is also measured using the above-mentioned stylus-type surface roughness measuring device.

Further, such an uneven hitting surface 3a is formed by a shot blast in which blast particles containing metal or ceramic particles having a diameter of more than 1.0 mm and not more than 2.0 mm are jetted toward the face surface 3. It can be formed using processing.

The metal sphere used in the shot blasting process can be made of, for example, stainless steel, iron, nickel, cobalt, or an alloy containing at least one of these elements. In addition, ceramic particles include
Preferably, those having a relatively large specific gravity, for example, silicon nitride ceramics, alumina ceramics, zirconia ceramics, and the like having a bulk density per unit volume of particles of 3.0 or more are particularly preferable. Further, not all such blast particles need to be included in the range of the diameter, but at least 50% or more of the blast particles used in the shot blast processing have the diameter and the particle diameters are substantially uniform. Is desirable.

In shot blasting of the face of a conventional iron golf club, the diameter is usually 250 μm.
Ceramic particles of small diameter, about 1.0
Particles smaller than mm are often used. In such small-sized blast particles, as shown in Table 1, the average inclination angle θa and the root mean square angle θq are both smaller than the range of the present invention. It is difficult to obtain a contact state.

In order to inject the blast particles to the face surface 3, for example, the blast particles are ejected from the tip of the nozzle using high-pressure air or the radius of the blast particles is increased by using the centrifugal force of a rotating impeller or the like. Various blasting devices, such as an impeller type jetting in a direction and a device using a liquid, can be used as appropriate. In the case of the nozzle type, for example, the treatment is performed using high-pressure air of about 1.8 to 5.3 kgf / cm ² , more preferably about 2.5 to 4.5 kgf / cm ^2, for an injection time of about 60 to 120 seconds. Is desirable.

Various conditions in the shot blasting process are appropriately set according to the material of the head H and so as to satisfy the ranges of the average inclination angle θa and the root mean square inclination angle θq. When plating is performed on the face surface 3, such a shot blasting process is performed regardless of before or after the plating or painting, provided that the average inclination angle θa and the root mean square inclination angle θq are satisfied. However, it is preferably performed after plating.

Although the embodiment of the present invention has been described in detail above, for example, in an iron golf club set, the average inclination angle θa and the root mean square inclination θq of the uneven hitting surface 3a of each golf club may be the same. It may be different within the above range.

[0047]

EXAMPLE An iron golf club set having a total of five iron golf club sets was prototyped according to the specifications shown in Table 2 (Examples and Comparative Examples). A trial hit test was performed with a swing robot, and the backspin amount, launch angle, Carry, run, and total flight distance were measured. The swing robot was set to have an iron golf club having a loft angle of 20 degrees and a head speed of 36.5 m / s.

The golf club of the embodiment is a cast product of stainless steel (SUS630), and has a diameter of 1.
Using a 5 mm metal ball as a main component and a nozzle type blasting device, shot blasting was performed on almost the entire hitting region at an injection pressure of 5 kgf / cm ² and an injection time of 60 seconds.
The golf club of the comparative example uses an alumina metal sphere having a diameter of 250 μm, and has an injection pressure of 3 kgf / cm ² and an injection time of 6 kg.
At 0 seconds, shot blasting was performed on almost the entire hitting area. Table 2 shows the club specifications and test results.

[0049]

[Table 2]

As a result of the test, in the iron golf club set of the example, the backspin amount of the ball hit by a golf club having a loft angle of less than 40 ° was smaller and the launch angle was smaller than that of the iron golf club set of the comparative example. Can be confirmed to be sufficiently large. Therefore, it can be confirmed that both the carry and the run exceed the comparative example. Further, in the examples, it can be confirmed that the backspin amount is increased, the run is small, and the controllability is excellent in the iron golf club having a loft angle of 40 ° or more.

[0051]

As described above, the iron golf club of the present invention has an average inclination angle θa of 0.15 on the face surface.
０．２0.25 (deg) and the root mean square angle θq is 0.20 to 0.30 (deg), so that the uneven hitting surface includes sharper peaks and valleys than before. It can be formed with a rough surface roughness. This allows the face surface to create a state of high friction with the ball. For example, in an iron golf club having a loft angle of 40 ° or more, such an uneven hitting surface is useful for reducing the run by increasing the initial spin amount of the ball, and an iron having a loft angle of less than 40 °. In the case of a golf club, it is useful to reduce the initial spin amount and increase the flight distance based on the above-mentioned new knowledge.

According to the third aspect of the present invention, from the golf club having the lowest loft angle (i = 1) to the golf club having the highest loft angle (i = q). In the iron golf club set in which a plurality of golf clubs are set, the average inclination θa is 0.15 to 0.2 on the face surfaces of all the golf clubs.
5 (deg) and the root mean square θq is 0.20
By including the irregular hitting surface of 0.30 (deg), it is possible to provide an iron golf club set capable of obtaining an optimum initial spin amount of a hit ball through all counts.

[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 a head thereof.

FIG. 3 is an explanatory view illustrating a method of measuring the surface roughness of a face surface using a stylus type surface roughness measuring device.

FIGS. 4A and 4B are diagrams illustrating cross-sectional curves.

FIGS. 5A and 5B are diagrams illustrating cross-sectional curves.

FIG. 6 is a graph showing a relationship between a surface state of a face surface and a back spin amount of a 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.

FIG. 10 is a graph showing a relationship between a surface state of a face surface and a launch angle of a hit ball.

FIGS. 11A to 11D are cross-sectional views illustrating a process of impact between a ball and a face surface.

FIG. 12 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 Irregular hitting surface S Shaft H Club head

Claims (3)

[Claims] 1. The face surface has an average inclination angle θa of 0.15.
An iron golf club comprising an uneven hitting surface having an angle of inclination of about 0.20 to 0.30 (deg) and a root mean square angle θq of 0.20 to 0.30 (deg). 2. The method according to claim 1, wherein the uneven hitting surface is formed by using a shot blasting process for spraying blast particles containing metal or ceramic particles having a diameter of more than 1.0 mm and not more than 2.0 mm. The iron golf club according to claim 1, wherein 3. The lowest count (i = 2) having the smallest 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. An iron characterized in that the surface includes an uneven hitting surface having an average inclination angle θa of 0.15 to 0.25 (deg) and a root mean square angle θq of 0.20 to 0.30 (deg). Golf club set.