JP2005137794A - Iron golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an iron golf club head obtaining a favorable driving feeling. <P>SOLUTION: This iron golf club head 1 is provided with at least a single curved narrow groove 4 which curvedly extends in a back face FCB of a face central area of the radius of 10 mm with a sweet spot SS, or a crossing point where a normal line lined from the head gravity center crosses with the face, as the center of the circle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an iron type golf club head useful for obtaining a good shot feeling.

  When a ball is hit with a golf club, the golfer's hands, arms, elbows, and the like are transmitted to the touch associated with the impact. This is called a shot feeling. In general, the feel at impact differs from club to club. In particular, iron-type golf club heads tend to feel a strong (or hard) feel at impact. Therefore, conventionally, a method for making the shot feeling of an iron type golf club head mild has been proposed by the following patent document, for example.

JP-A-9-239077 JP 2000-225217 A

  Patent Document 1 describes a configuration in which a recess is provided in the back portion of the head, leaving a peripheral edge, and a vibration absorbing material is disposed in the recess. Patent Document 2 is composed of a face insert and a head body that receives the face insert. A groove extending vertically and horizontally is formed in the face insert receiving portion of the head body, and an elastomer or the like is formed between the head body and the face insert. Filling with vibration damping material is described.

  The improvement of the hit feeling in the conventional iron type golf club head is based on the idea that the vibration generated on the face hitting the ball is attenuated by using a vibration damping material such as an elastomer. However, the premise of such an idea has the disadvantages that the manufacturing process is likely to be complicated when the elastomer is disposed, and the cost is increased. Moreover, since the head weight increases due to the elastomer or the like, the degree of freedom in designing the center of gravity of the head is impaired. In other words, since the total head weight has certain restrictions, the weight that can be used to adjust the center of gravity of the head decreases as the head weight increases.

  The present invention has been devised in view of the above-mentioned problems, and is based on the fact that at least one bent narrow groove that bends and extends at the back of the center area of the face surface. An object of the present invention is to provide an iron type golf club head capable of reducing the vibration of the entire head and thereby improving the feel at impact by generating vibrations that cancel each other.

  The invention according to claim 1 of the present invention is an iron type golf club head, and a face having a radius of 10 mm centered on a sweet spot, which is a point where a normal line lowered from the center of gravity of the head to the face surface intersects the face surface. An iron-type golf club head, characterized in that at least one bent fine groove that is bent and extended is provided on the back surface of the center area of the surface.

  The invention according to claim 2 is characterized in that the bent narrow groove has a groove width of 0.25 to 1.50 mm and a groove depth of 0.20 to 0.50 mm. This is an iron type golf club head.

  According to a third aspect of the present invention, in the bent narrow groove, a separation length from the reference curve of a maximum separation portion farthest from a reference straight line connecting both ends thereof is 3 to 15 mm. Or it is an iron type golf club head of 2.

  According to a fourth aspect of the present invention, in the iron according to any one of the first to third aspects, the bent narrow groove has a length of 20 to 65 mm included in the back surface of the central area of the face surface. Type golf club head.

  In the invention according to claim 5, the bent narrow groove is formed of an arcuate curve that is convex or concave from the sole portion side toward the top portion side, and a reference straight line connecting both ends thereof is in the toe and heel directions. 5. The iron type golf club head according to claim 1, wherein the head is substantially horizontal with respect to the angle of 35 ° or less.

  When a ball is hit on the face surface, the face portion bends due to elastic deformation. The elastic strain energy stored in the head by this deformation vibrates the head (converted into kinetic energy and consumed). In order to mildly hit the shot, it is effective to attenuate this vibration as quickly as possible. The largest vibration of the head is in the vicinity of the face portion, particularly the hitting ball portion. In the present invention, at least one bent fine groove that is bent and extended is provided on the back surface of the center area of the face surface that can be regarded as the vicinity of the hit ball portion. The bent narrow groove functions to shift the vibration period between one side and the other side of the face portion. This interaction cancels out the vibrations, thereby leading to faster vibration damping of the head.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 is a front view of an iron type golf club head in a reference state as one embodiment of the present invention, FIG. 2 is a rear view thereof, FIG. 3 is an enlarged end view of FIG. Each is shown. An iron type golf club head (hereinafter sometimes simply referred to as a “head”) 1 of the present embodiment is a plate-like face that constitutes at least a part (main part in this example) of a face surface F that strikes a ball. Examples include a member 2 and a head main body 3 having the face member 2 disposed on the front surface.

  The reference state is a state in which the head 1 is set to a predetermined lie angle α and loft angle β (real loft angle) determined for the head and is grounded to the horizontal plane HP. Further, the lie angle α is inclined with respect to an axial center line CL of a shaft insertion hole 3eh of the shaft attachment portion 3e described later.

  For example, as shown in FIG. 4, the head body 3 includes a top frame 3 a extending obliquely at the upper part of the head, a sole frame 3 b forming the lower part of the head, and a toe frame 3 c that connects between these at the front end side of the head. The head portion includes a neck portion 3d that connects the top member 3a and the sole portion frame 3b on the heel side of the head, and a shaft attachment portion 3e into which a shaft (not shown) extends upward from the neck portion 3d. In the present embodiment, the head body 3 is surrounded by a top frame 3a, a toe frame 3c, a sole frame 3b and a neck 3d, and an opening O penetrating in the front-rear direction is formed. The head main body 3 is not particularly limited, but is preferably made of stainless steel or a metal material having a relatively high specific gravity, such as SUS630, SUS255, or SUS450.

  A face member mounting portion 10 having a stepped cross section is formed on the periphery of the opening O. For example, the face member mounting portion 10 faces the outer peripheral surface e of the face member 2 and rises toward the center of the head on the inward surface 10a fitted to the outer peripheral surface e and on the rear end side of the inward surface 10a. An annular supporting surface 10b that includes a wall shape and supports a peripheral portion of the back surface 2B of the face member 2 is included. The inward surface 10a has substantially the same contour shape as the outer peripheral surface e of the face member 2, and has a depth dimension substantially the same as the thickness of the outer peripheral surface e.

  A back wall portion 11 is provided on the sole portion frame 3 b of the head main body portion 3. As shown in FIG. 3, the back wall portion 11 rises at a small height at a position separated from the back surface 2 </ b> B of the face member 2. Such a back wall portion 11 forms a pocket-shaped cavity C between the back surface of the face member 2 and distributes more weight to the rear of the head, thereby setting the center of gravity of the head 1 deeper. To help.

  The face member 2 has a plate shape having a substantially flat surface 2A on the face surface F side, a back surface 2B on the opposite side, and an annular outer peripheral surface e extending therebetween. However, the surface 2A may be provided with a face line 12 extending horizontally in a reference state. The outer peripheral surface e of the face member 2 is supported by the inward surface 10a of the face member mounting portion 10 and the peripheral portion of the back surface 2B is supported by the support surface 10b, respectively. For example, by caulking, bonding, or other fixing means. It is fixed. Thus, the head 1 forms a face portion FP that defines a continuous face surface F between the surface 2A of the face member 2 and the front surface of the head main body portion 3.

  FIG. 5 shows a perspective view of the face member 2 of the present embodiment as viewed from the back surface 2B side. The back surface 2B is provided with a concave portion 5 that continuously extends in an annular shape at a position substantially equidistant from the outer peripheral surface e. As a result, the face member 2 is provided with a central thick part 6 having a thickness t1 and being surrounded by the concave part 5 and a peripheral thick part 7 having a thickness t2 forming the outside of the concave part 5. The thickness t3 of the portion provided with the recess 5 is smaller than any of the thicknesses t1 and t2.

  The central thick portion 6 is formed in a horizontally long substantially elliptical shape including the sweet spot SS. Therefore, the surface side is a portion that frequently hits the ball. As shown in FIG. 3, the sweet spot SS is a point where a normal line N dropped from the center of gravity G of the head to the face surface F intersects the face surface F. The thickness t1 of the central thick portion is not particularly limited, but is preferably 2.5 mm or more, more preferably 2.7 mm or more, and the upper limit is 3.5 mm or less in combination with any of the above lower limits. More preferably, the thickness is 3.2 mm or less. When the thickness t1 is less than 2.5 mm, the durability tends to be reduced. Conversely, when the thickness t1 exceeds 3.5 mm, the overall rigidity of the face member 2 is increased and the resilience performance tends to deteriorate.

  Further, it is desirable that the thickness t2 of the peripheral thick portion 7 is equal to or smaller than the thickness t1 of the central thick portion 6 by about 0.2 mm. As shown in FIG. 3, since the peripheral thick portion 7 is supported by the face member mounting portion 10, even if the thickness t2 is too small, the mounting strength is insufficient. There is a tendency to reduce the resilience performance.

  Further, the thickness t3 of the recess 5 is not particularly limited, but is preferably 1.6 mm or more, more preferably 1.7 mm or more. The upper limit is any one of the above lower limits. In combination, it is 2.3 mm or less, more preferably 2.0 mm or less. If the thickness t3 is too small, the durability of the face member 2 tends to be deteriorated. On the other hand, if the thickness t3 is too large, it is difficult to improve the resilience of the head.

  The face member 2 is preferably formed of, for example, a titanium alloy (Ti-6Al-4V). The titanium alloy has a specific gravity smaller than that of stainless steel or the like constituting the head body 3. For this reason, the weight of the head can be more distributed to the periphery of the face member 2, which helps to increase the sweet area. However, it goes without saying that other materials than the titanium alloy, such as SUS450 (maraging copper), may be used for the face member 2.

  The head 1 of the present invention is provided with at least one bent fine groove 4 which is bent and extended on the back surface FCB of the face surface center region FC which is a region having a radius of 10 mm centered on the sweet spot SS. Here, the back surface FCB of the face surface center region means a region obtained by projecting the face surface center region FC perpendicularly from the face surface F onto the back surface of the face part FP. In the present embodiment, the back surface FCB of the center area of the face surface is an area including more of the central thick part 6.

  The head 1 collides with the ball more at the sweet spot SS on the face surface F. As a result, the face surface center region FC is bent most greatly by elastic deformation and vibrates greatly. The larger the vibration, the more the golfer's hand, arm, or elbow acts as a load, and the golfer feels an unfavorable shot feeling. In order to make the shot feeling milder, it is important to attenuate the vibration of the face surface center region FC as quickly as possible.

  As a result of various experiments, the inventors have found that the face surface central region FC has a large size by a simple configuration in which at least one bent narrow groove 4 is bent and extended on the back surface FCB of the face surface central region. It was found from the results of various experiments that the vibration was damped relatively early. That is, as shown in the rear view of the face member 2 in FIG. 6, when the bent narrow groove 4 is provided across the rear face FCB in the center area of the face surface, the vibration waveform at the upper position of the bent narrow groove 4 generated immediately after hitting the ball It has been found that the frequency and amplitude of the vibration waveform at the lower position are different from each other, and in a preferred embodiment, phase inversion occurs due to a 1/2 cycle shift.

  The superposition principle works for the vibration wave. That is, as shown in FIG. 7A, when two waves A or B having the same phase are superposed, a wave C having a large amplitude is obtained by strengthening each other. When B is superposed, the energy C cancels each other, and as a result, the superposed wave C becomes a wave C having a small amplitude. For this reason, the wave A and the wave B in FIG. 6 having different phases cancel each other, and as a result, the wave C obtained by superimposing these waves has a small amplitude and causes rapid attenuation of vibration energy. Thereby, the vibration of the face surface center area FC is quickly absorbed and relaxed, and the feel at impact on the golfer's hand can be improved.

  On the other hand, as shown in FIG. 8, when one straight narrow groove is provided on the back surface FCB in the center area of the face surface, the vibration waveform at the upper position and the vibration waveform at the lower position generated immediately after hitting the ball are: It has been found that the frequency C and the amplitude are substantially equal to each other, and the waves C obtained by superimposing these are intensified with each other to generate a large wave C.

  The reason why the vibration frequency and amplitude of the narrow groove 4 provided on the back surface FCB in the center area of the face surface is different in the upper and lower areas will require further analysis in the future. I can explain. First, since an iron type golf club head has a low sweet spot SS and often hits a ball placed on the ground, a relatively large vibration occurs particularly in the lower side of the center area of the face surface. In addition, when the bent narrow groove 4 is provided as shown in FIG. 6, the vertical spans Y1, Y2 from the narrow groove 4 to the lower edge of the face member 2 are below the bent narrow groove 4 that generates strong vibration. It can be mentioned that Y3 is not uniform in the toe-heel direction. Therefore, the vibration modes on the upper side and the lower side of the narrow groove 4 of the face are different, and this is the phase difference (wavelength shift) between the vibration wave A generated at the upper position and the vibration wave B generated at the lower position. It is inferred that this occurs. These waves overlap to determine the vibration characteristics of the entire head.

  In the case of the horizontal straight groove shown in FIG. 8, the vertical span between the straight thin groove and the lower edge of the face member 2 is substantially uniform in the toe and heel directions. For this reason, the wave A observed at the upper position and the wave B observed at the lower position appear in the same phase with no wavelength shift. In view of this, it can be assumed that even if the straight narrow groove is inclined rather than horizontal, the same effect as that of the bent narrow groove can be obtained. However, in this case as well, since the change in the span is a monotonous change such as an increase or decrease in the toe and heel directions, the phase shift of the wave is very small and the vibration damping effect cannot be sufficiently obtained.

  From such a viewpoint, the bent narrow groove 4 is particularly preferably an arcuate curve that is convex or concave from the sole frame 3b side to the top frame 3a side. Further, if the bent narrow groove 4 is partially included in the back surface FCB in the center area of the face surface, the above-described effects can be exhibited. Therefore, as in the present embodiment shown in an enlarged manner in FIG. 9, it is a matter of course that both ends 4a to 4b of the bent narrow groove 4 may protrude from the back surface FCB in the center area of the face surface. Both may be included in the back surface FCB of the center area of the face surface.

  The bent narrow groove 4 is preferably formed with a groove width of 0.25 to 1.50 mm and a groove depth of 0.20 to 0.50 mm. If the groove width of the bent narrow groove 4 is less than 0.25 mm or the groove depth is less than 0.20 mm, the effect of affecting the vibration mode of the face portion when the ball is hit is reduced. When it is larger than 1.50 mm or the groove depth is larger than 0.50 mm, stress concentration tends to occur in the bent fine groove 4 at the time of hitting, and the durability of the face part FP tends to be deteriorated. Particularly preferably, the lower limit of the groove width is 0.35 mm or more, the upper limit is 1.0 mm or less, more preferably 0.75 mm or less, and particularly preferably 0.65 mm or less. The lower limit of the groove depth is more preferably 0.25 mm or more, and the upper limit is more preferably 0.4 mm or less, and particularly preferably 0.35 mm or less. The groove width or depth may be constant over the entire groove length, or may be changed as appropriate. Although not shown in the drawings, the cross-sectional shape of the bent thin groove 4 is preferably a semicircular shape in order to avoid stress concentration, but various shapes such as a rectangular square groove shape and a triangular groove shape can also be adopted. Needless to say.

  Further, it is desirable that the bending narrow groove 4 has a separation length T from the reference curve BL of the maximum separation portion 4T farthest from the reference straight line BL connecting both ends 4a and 4b thereof is 3 to 15 mm. This separation length T is a measure of the degree of bending of the bent thin groove 4, and when the separation length T is less than 3 mm, the groove shape approaches a straight line and the above-described vibration damping effect cannot be fully exhibited. On the contrary, when 15 mm is larger than that, for example, in the case of a single arc, it is difficult to locate the back surface FCB in the center area of the face surface, and the range in which the narrow groove 4 affects the vibration tends to decrease. There is. The separation length T is particularly preferably 4 mm or more, more preferably 5 mm or more, and the upper limit is preferably 12 mm or less, more preferably 10 mm or less in combination with any of the lower limit values.

  The bent narrow groove 4 of the present embodiment has a substantially horizontal shape in which the reference straight line BL connecting the both ends 4a and 4b forms an angle θ of 35 ° or less, more preferably 20 ° or less with respect to the toe and heel directions. Is effective in enhancing the vibration absorbing effect. Note that the toe and heel directions mean horizontal lines in the reference state.

  FIG. 10 shows an example of the relative relationship between the bent narrow groove 4 and the back surface FCB in the center area of the face surface. (A) to (C) show an example in which the bent narrow grooves 4 are formed symmetrically with respect to a vertical line passing through the sweet spot SS. In these examples, each of the bent narrow grooves 4 is formed along an arcuate curve having a single radius of curvature R. When the bent thin groove 4 is formed with such an arc curve, the radius of curvature R is preferably 1 inch or more and 5 inches or less (25.4 mm or more and 127 mm or less). This is based on the same reason as the definition of the separation length T of the maximum separation portion 4T.

  In FIG. 10A, the maximum separation portion 4T of the bent narrow groove 4 coincides with the sweet spot SS. In the case (B), the maximum separation portion 4T is located higher than the sweet spot SS, and in the case (C), the maximum separation portion 4T is provided lower than the sweet spot SS. Preferred results are obtained for both chair and embodiment. FIGS. 10D to 10E show a mode in which the maximum separation portion 4T is displaced from the sweet spot SS on the heel side and the toe side. As a particularly preferable aspect, it is preferable that the distance between the sweet spot SS and the maximum separation portion 4T is 7.5 mm or less. That is, since the face portion is most easily deformed (easily bent) at the sweet spot SS, the vibration can be effectively attenuated by bringing the maximum separating portion 4T that vibrates well closer to the sweet spot. More preferably, the distance between the sweet spot SS and the maximum separation portion 4T is 6.0 mm or less, more preferably 5.0 mm or less, and more preferably 3.0 mm or less.

  FIG. 11 shows an example of a specific shape of the bent narrow groove 4. (A) is an arc having a single radius of curvature as shown in FIG. 10, and (B) is a first arc 4A, 4A having a small radius of curvature R1, and a second larger than that. The example which combined the 2nd circular arc 4B which consists of curvature radius R2 is shown. The combination position, the radius of curvature, and the number of types of arcs are not limited to those illustrated. Moreover, as shown in (C), it is possible to include a straight line in part. FIG. 4D is a drawing of an arc curve that protrudes from the top portion frame 3a side to the sole portion frame 3b side. Further, FIG. 4E shows a sinusoidal shape of one cycle. FIG. Shows a sine wave that repeats in a plurality of cycles, and any of them may be used.

  Further, it is desirable that the length L included in the back surface FCB of the center area of the face surface is 20 to 65 mm. If the length L is smaller than 20 mm, the region where vibration is attenuated by the bent narrow groove 4 becomes small, and there is a tendency that the effect of improving the feel at impact is not sufficiently obtained. On the other hand, when the length L is larger than 65 mm, the back surface FCB in the center area of the face surface tends to have an irregular shape and the appearance tends to be remarkably deteriorated. The length L is particularly preferably 25 mm or more, more preferably 30 mm or more, and the upper limit is preferably 60 mm or less, more preferably 55 mm or less in combination with any of the lower limits. The length L is a so-called path length along the bent narrow groove 4.

  Moreover, although the preferable aspect which the convex thin groove 4 of this embodiment becomes convex toward the top part frame 3a side from the sole part frame 3b side is shown, conversely, the top part is shown from the sole part frame 3b side. It is also possible to add an arcuate curve that becomes concave toward the frame 3a to the upper side. That is, as shown in FIG. 12, two or more bent fine grooves 4 can be provided on the back surface FCB in the center area of the face surface. In this embodiment, an upper bent narrow groove 4U extending upward and a lower bent narrow groove 4D extending lower are included.

  The iron type golf club head of the above embodiment is exemplified by the face member 2 and the head main body 3 made of a different material. However, the present invention can also be applied to an integrally structured head. . As shown in FIG. 3, it is particularly preferable that the length Z from the leading edge Le (the portion protruding most forward in the reference state) to the bottom of the cavity C along the face surface F is 10 mm or less. is there. In such a head, since the free deflection region (portion facing the cavity C) of the face is large, the face is particularly easy to vibrate, and thus the effect of the present invention becomes more remarkable. If Z> 10 mm, the resilience performance of the head tends to deteriorate. Other than the cavity type, for example, the present invention can be applied to a hollow type iron type golf club head.

A test for feel at impact was performed on an iron type golf club head (# 5) based on the specifications shown in FIG. 13 and Table 1. Each head has the specifications shown in FIG. 13 for the bent narrow grooves, and the other heads have the same basic structure shown in FIGS. Specifically, the face member was Ti-6Al-4V, the head body was a SUS630 lost-wax precision cast product, and these were fixed together by pressing them together. Each of the bent narrow grooves or narrow grooves formed on the back surface of the center area of the face surface was recessed by NC processing with a width of 0.50 mm and a depth of 0.30 mm. Manufacture was very easy. In addition, each of the bent thin grooves of the embodiment is formed by an arc curve having a single radius of curvature. Comparative Example 2 does not have any bent narrow grooves.
The test procedure is as follows.

<Impact force when hitting a ball>
As shown in FIG. 14, impact force sensors S1 and S2 are attached to the neck portion and the sole portion of each test head, and a ball fired at a speed of 34.5 m 2 / s on the sweet spot of the head that is freely supported. The maximum impact force (kgf) at that time was measured. It shows that the vibration at the time of hitting is absorbed, so that a numerical value is small. A golf ball having a natural frequency of 900 Hz was used.

<Hitball feeling>
Each test head is fitted with the same carbon shaft, and each golf club with a handicap 15 to 25 is used to hit 20 balls on the natural grass using each test club. Evaluation was made by a five-point method using a ring. The results were evaluated using the average score of all golfers. The larger the value, the better. The test results are shown in Table 1.

  As a result of the test, it can be quantitatively confirmed that the head of the example absorbs the impact force significantly. In addition, an actual golfer can significantly improve the feel at impact in the feeling test.

1 is a front view of an iron type golf club head showing an embodiment of the present invention. FIG. It is AA sectional drawing of FIG. It is a disassembled perspective view of a head. It is the perspective view seen from the back side of the face member. It is a diagram which illustrates the wave of vibration of position A thru / or B of the face concerning the present invention. (A) And (B) is a diagram explaining the principle of the superposition of a wave. It is a diagram which illustrates the wave of vibration of position A thru / or B of a face concerning a comparative example. It is an enlarged rear view of a face member. (A)-(E) are the schematic which shows embodiment of a bending thin groove. (A)-(F) are the schematic which shows the specific example of the groove shape of a bending thin groove. It is a rear view of a face member. (A)-(E) are the rear views of the face member of an Example and a comparative example. 1 is a schematic diagram illustrating a test method for measuring an impact force upon hitting a ball.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Iron type golf club head 2 Face member 3 Head main-body part 4 Bending thin groove 4a, 4b Both ends 4T of bending fine grooves Maximum separation part BL of bending fine groove Reference curve of bending fine groove

Claims (5)

  An iron-type golf club head, which is bent at least on the back surface of a central area of the face surface having a radius of 10 mm centered on a sweet spot, which is a point where a normal line lowered from the center of gravity of the head to the face surface intersects the face surface. An iron type golf club head provided with one bent narrow groove.   2. The iron type golf club head according to claim 1, wherein the bent narrow groove has a groove width of 0.25 to 1.50 mm and a groove depth of 0.20 to 0.50 mm.   3. The iron-type golf club according to claim 1, wherein the bent narrow groove has a separation length from the reference curve of a maximum separation portion furthest away from a reference straight line connecting both ends thereof, from 3 to 15 mm. head.   The iron-type golf club head according to any one of claims 1 to 3, wherein the bent narrow groove has a length of 20 to 65 mm included in a back surface of the center area of the face surface.   The bent narrow groove has an arcuate curve that is convex or concave from the sole side toward the top side, and the reference straight line connecting both ends thereof is substantially horizontal at 35 ° or less with respect to the toe and heel directions. The iron-type golf club head according to any one of claims 1 to 4, wherein the iron-type golf club head has a shape of a circle.

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