JP5296344B2 - Golf club head manufacturing method and golf club head - Google Patents

Description

  The present invention relates to a golf club head, and more particularly to a score line on a face surface.

  Generally, a plurality of linear grooves parallel to each other in the toe-heel direction are formed on the face surface of a golf club head (Patent Documents 1 and 2). This groove is called a score line, a marking line, a face line, etc. (referred to as a score line in this document). This score line has an effect of increasing the backspin amount of the hit ball or suppressing the backspin amount of the hit ball from being remarkably reduced in the case of a rainy day or a shot from the rough. Examples of the method for forming the score line include cutting, forging, and casting.

JP-A-10-248974 JP 2005-169129 A

  However, the width of the score line is narrow. For example, in the case of a golf club head for competition, the rule defines that the width of the score line is 0.9 mm or less. Therefore, it is not always easy to form a plurality of score lines in parallel with each other and in a straight line. For example, when a score line is formed by cutting, a slight distortion may occur in the score line due to blurring or wear of the cutting tool or distortion of the material constituting the face surface. Even in the case of forming by forging, a slight distortion may occur in the score line due to the distortion of the material constituting the face surface. In the case of forming by casting, slight distortion may occur in the score line due to the occurrence of sink marks. If the score line is distorted, the appearance of the score line is deteriorated, and there is a fear that individual differences in performance of each product may occur.

  An object of the present invention is to provide a golf club head in which a score line with less distortion is formed.

According to the present invention, in a golf club head manufacturing method in which a plurality of score lines are formed on a face surface, a first forming step of forming grooves to be score lines on the face surface and the first forming step are formed. A golf club head comprising : a second forming step of cutting an edge of the groove, and forming a notch having an arcuate cross-sectional shape uniformly in the longitudinal direction of the groove. A method is provided.

  In the present invention, the score line having the notch is formed by forming the groove in the first forming step and cutting the edge of the groove in the second forming step to form the notch. . Since only the edge of the groove is cut in the second forming step, the amount of cutting can be reduced, and the cutting tool can be shaken and worn, or the distortion of the material constituting the face surface can be reduced, and processing with higher accuracy can be performed. The appearance and performance of the score line depend on the boundary portion between the score line and the face surface, and the notch constituting the boundary portion is processed with higher accuracy in the second forming step. Therefore, the processing accuracy of the score line is substantially increased. Therefore, it is possible to provide a golf club head in which a score line with less distortion is formed.

According to the present invention, in the golf club head in which a plurality of score lines are formed on the face surface, the score lines are formed by forming the grooves to be the score lines and then cutting the edges of the grooves. The golf club head is characterized in that an arc-shaped cutout having a cross-sectional shape is formed uniformly in the longitudinal direction of the groove, one for each edge .

  As described above, according to the present invention, it is possible to provide a golf club head in which a score line with less distortion is formed.

  FIG. 1 is an external view of a golf club head 1 according to an embodiment of the present invention. The example in the figure shows an example in which the present invention is applied to an iron type golf club head. However, the present invention can also be applied to wood type or utility type golf club heads.

  The golf club head 1 has a plurality of score lines 20 formed on the face surface 10 thereof. Each score line 20 is a linear groove extending in the toe-heel direction and parallel to each other. In the present embodiment, the arrangement intervals (pitch) of the score lines 20 are equal intervals (equal pitch), but the arrangement intervals may be different. FIG. 2 is a cross-sectional view of the score line 20 in a direction orthogonal to the longitudinal direction (toe-heel direction) and a partially enlarged view thereof. In the present embodiment, the cross-sectional shape of the score line 20 is the same except for both ends in the longitudinal direction. Each score line 20 has the same cross-sectional shape.

  In the case of this embodiment, the cross-sectional shape of the score line 20 is a substantially trapezoid. However, the cross-sectional shape of the score line 20 is not limited to this, and may be a substantially square shape or a substantially triangular shape. In the present embodiment, the cross-sectional shape of the score line 20 is symmetrical. At the edge of the score line 20 (boundary portion with the face surface 10), a cutout 21 having an arcuate cross-sectional shape is formed uniformly in the longitudinal direction of the score line 20. In the case of this embodiment, the cross-sectional shape of the notch 21 is an arc shape that is a part of a circle having a radius r, but may be an elliptical arc shape.

  The tangent of the arc of the cross-sectional shape of the cutout 21 at the boundary point P1 between the cutout 21 and the face surface 10 (here, the tangent of a circle with a radius r) forms an angle θ1. This angle θ1 affects the frictional force between the golf ball and the face surface 10 that occurs during a shot. When the notch 21 is formed so that the angle θ1 is increased, the backspin amount of the golf ball can be increased, but the golf ball is easily damaged. Conversely, if the notch 21 is formed so that the angle θ1 is small, the backspin amount of the golf ball is reduced, but the ball can be prevented from being damaged.

  Next, a method for forming the score line 20 will be described. In the present embodiment, in forming the score line 20, first, a groove to be the score line 20 is first formed on the face surface 10 (first forming step). Hereinafter, this groove is referred to as a primary formation groove. Next, the edge of the primary forming groove is cut to form the notch 21 (second forming step), and the score line 20 is completed.

  For the cutting process for forming the notch 21, for example, an NC (numerical control) milling machine can be used to perform a cutting process with higher accuracy. The primary forming groove may be formed by, for example, cutting, forging, or casting. However, when the NC milling machine is used for forming the notch 21, the cutting process is performed. Is preferably cut by the same NC milling machine. Hereinafter, the case where the formation of the primary forming groove and the formation of the notch 21 are continuously performed by the same NC milling machine will be described.

  FIG. 3 (A) is a schematic diagram showing an example of cutting a primary groove by an NC milling machine. A golf club head 1 ′ having an unprocessed score line 20 is fixed to an NC milling machine via a jig 2. In the present embodiment, the case where the face surface 10 is integrally formed with the golf club head will be described. However, the face member constituting the face surface 10 and the head body may be joined as separate members. In this case, the score line 20 may be formed by fixing the face member to the NC milling machine.

  The NC milling machine has a spindle 3 that is driven to rotate about an axis Z, and a cutting tool (end mill) 4 is attached to the lower end of the spindle 3. Thus, in the NC milling machine, after setting the plane coordinates of the face surface 10, the spindle 3 is rotated and the face surface 10 (golf club head 1 ′) or the cutting tool 4 is relative to the formation direction d 1 of the score line 20. The primary forming groove is formed by cutting the face surface 10 while moving to. When one primary forming groove is formed, after the cutting tool 4 is separated from the face surface 10, the cutting tool 4 is relatively moved in a direction orthogonal to the forming direction d1 of the score line 20, and the next primary forming groove is formed. By forming, primary formation grooves are sequentially formed. The position of each primary forming groove is numerically controlled according to design data. FIG. 3B is a diagram showing an example of a cross-sectional shape of the primary formation groove 20 ′ formed in the first formation step.

  Next, when the formation of all the one formation grooves is completed, the processing of the notch 21 is started. In this case, the cutting tool 4 is replaced with a ball mill or the like. FIG. 4A shows an example of processing when the cutting tool 4a that simultaneously processes the notches 21 on both sides of the primary forming groove 20 ′ is used. FIG. 4B shows a processing example in the case where the notch 21 is processed with the rotation axis Z of the cutting tool 4 b inclined relative to the face surface 10. In this case, it is necessary to use an NC milling machine capable of adjusting the inclination angle of the rotation axis Z relative to the face surface 10. In any case, the cross-sectional shape of the notch 21 depends on the tip shape of the cutting tools 4a and 4b. The angle θ1 in FIG. 2 depends on the tip shape of the cutting tools 4a and 4b and the cutting position.

  Thus, each notch 21 is formed on the face surface 10 (golf club head 1 ′) or the cutting tool (4a, 4b) in the formation direction d1 of the score line 20 (FIG. 3 (FIG. 3). It is formed by cutting the edge of the primary forming groove 20 ′ while moving relatively to A)). The position of each notch 21 is numerically controlled according to the design data. When the formation of the notches 21 is completed, the score line 20 having the cross-sectional shape shown in FIG. 2 is completed. After that, the surface of the face surface 10 may be cut as a surface finish of the face surface 10.

  In the present embodiment, the score line 20 having the notch 21 is formed by forming the primary forming groove 20 ′ and then cutting the edge of the primary forming groove 20 ′ to form the notch 21. Form. In the formation of the notch 21, only the edge of the primary forming groove 20 ′ that has already been processed is cut, so that the amount of cutting can be reduced, and the shaving and wear of the cutting tool or the distortion of the material constituting the face surface 10 is small. Higher precision machining is possible. The appearance and performance of the score line 20 depend on the boundary portion between the score line 20 and the face surface 10, and the notch 21 constituting the boundary portion is processed with higher accuracy. In addition, the processing accuracy of the score line 20 is increased. Therefore, it is possible to provide the golf club head 1 in which the score line 20 with less distortion is formed. Further, as a secondary effect, the backspin amount of the golf ball and the ease of scratching the golf ball can be adjusted by the size of the angle θ1 in FIG.

  In the cutting of the notch 21, it is desirable that the cutting amount is small in terms of machining accuracy and reduction of wear of the cutting tool. Therefore, the maximum cutting depth from the top of the edge of the primary forming groove 20 ′ by the cutting tool is preferably 0.1 mm or less, for example. More specifically, in FIG. 3B, it is desirable that the notch 21 is formed within a range of a virtual circle C having a radius of 0.1 mm centered on the vertex P2 of the edge of the primary formation groove 20 ′.

  FIG. 5A shows scoring measurement data of the example of the present invention, and FIG. 5B shows scoring line measurement data of the comparative example. In the score line of the example, the primary forming groove and the cutout were formed by an NC milling machine. The groove depth of the primary groove is 0.45 mm (design value), the edge angle (angle θ2 in FIG. 3B) is 60 degrees (design value), and the groove width (W2 in FIG. 3B) is 0. The notch was an arc with a radius of 0.2 mm (design value), and the angle θ1 (see FIG. 2) was 35 degrees (design value). The score line of the comparative example was formed by casting and had no portion corresponding to the notch of the example (the same shape as the primary forming groove of the example). The groove depth of the score line of the comparative example was 0.45 mm (design value), the edge angle was 60 degrees (design value), and the groove width was 0.7 mm (design value).

  5A and 5B, “groove width and measurement position (mm)” are measured values of the groove width at a plurality of positions on the score line, and the groove width W1 of FIG. . In the present embodiment, three score lines are set as measurement targets. 0, ± 1 to ± 4 indicating the measurement position are assumed to be based on a virtual line (line L1 in FIG. 1) that passes through the contact point with the ground when the golf club head is sole and is orthogonal to the score line (measurement position = 0). Shows the position. A position separated from the line L1 toward the toe side is indicated by a symbol-, and a position separated from the heel side is indicated by a symbol +. For example, “+1” means a position shifted by 1 mm from the line L1 toward the heel side, and “−2” means a position shifted by 2 mm from the line L1 toward the toe side.

  The standard deviation (same groove) indicates the standard deviation of the groove width at each position on the same score line. The standard deviation average value (same groove) is the average value of the standard deviations (same groove) of the four score lines. is there. The error range (same groove) indicates the difference between the maximum value and the minimum value of the groove width at each position on the same score line. The error range average value (same groove) is the error range of the four score lines (same groove). ) Average value.

  The standard deviation (between grooves) indicates the standard deviation of the groove width at the same position on each score line, and the standard deviation average value (between grooves) is the average value of the standard deviations (same groove) at all measurement positions. . The error range (between grooves) indicates the difference between the maximum value and the minimum value of the groove width at the same position on each score line, and the average error range (between grooves) is the error range (between grooves) of all measurement positions. Is the average value.

  From the measurement data of FIGS. 5A and 5B, it can be seen that the accuracy of the groove width of the score line of the example is significantly higher than the accuracy of the groove width of the score line of the comparative example. In particular, when comparing between grooves, there is a significant difference.

  Next, FIG. 6 shows the score line groove width (groove in FIG. 2) when the edge angle of the primary groove (angle θ2 in FIG. 3B) and the notch angle θ1 (see FIG. 2) are changed. It is a figure which shows evaluation of the measurement of the actual value of width W1), workability, and a test hit result. The target was 12 golf club heads (No. 1 to 12). For the golf club heads 1, 2, and 12, notches were not formed, and only the primary grooves were processed.

  In FIG. 6, “at the time of primary formation” indicates the design value of the groove width of the primary formation groove (W2 in FIG. 3B), the edge angle (angle θ2 in FIG. 3B), and the evaluation of workability. ing. “After notch formation” indicates the measured value of the groove width (W1 in FIG. 2), the design value of the notch angle θ1 (see FIG. 2), and the evaluation of workability. “Test hit result” indicates a test hit result of a golf club using each golf club head.

  No. 3-No. As in the case of 11 golf club head, by changing the angle θ2 of the primary groove edge and the angle θ1 of the notch, it is possible to realize score lines of a plurality of types of groove widths. By providing the notches, not only the processing accuracy of the score line can be improved, but also the degree of freedom in designing the groove width can be improved.

  Regarding the workability of the primary groove, No. 1 and no. In the golf club head of No. 2, the angle θ2 was large, so that the workability was not so good due to the problem of draft gradient. No. 3-No. There was no particular problem with the 12 golf club heads. Therefore, from the viewpoint of workability of the primary forming groove, it is desirable that the angle θ2 is less than 85 degrees. In addition, when the notch is processed, it is preferable that the angle θ2 of the edge of the primary forming groove is small because vibration and cutting resistance of the cutting tool are small. However, if the angle θ2 is too small, the sectional area of the groove becomes small. This is not desirable because it tends to have a low spin tendency (less backspin) during shots. Therefore, it is desirable that the angle θ2 of the edge of the primary groove is 60 degrees to 80 degrees.

  Regarding the workability of notches, In the golf club head of No. 5, the angle θ1 was so gentle that it was difficult to obtain accuracy. Therefore, from the viewpoint of workability, the angle θ1 is desirably 20 degrees or more.

  As for the test hit result, it is desirable that the notch angle θ1 is large from the viewpoint of increasing the spin amount of the ball, but the ball is easily damaged. No. In the golf club head of No. 9, the ball was easily scratched. In the golf club head of 8, the ball was not so damaged. Therefore, from the viewpoint of making it difficult to damage the ball, the notch angle θ1 is preferably less than 65 degrees, and more preferably 60 degrees or less. Moreover, No5. The golf club head had a low spin rate. Therefore, from the viewpoint of the spin amount of the ball, the notch angle θ1 is preferably 20 degrees or more.

  Therefore, from the viewpoint of workability, spin rate, and the difficulty of scratching the ball, it is desirable that the notch angle θ1 is 20 degrees or more and 60 degrees or less. In addition, No. In the golf club head of No. 12, there was a case where the spin rate was greatly reduced in the shot from the rough. 1-No. With the 11 golf club heads, the spin rate was not significantly reduced in the shot from the rough. This is no. In the 12 golf club head, the angle θ2 is small and the groove volume is small, so it is presumed that the turf was easy to bite.

1 is an external view of a golf club head 1 according to an embodiment of the present invention. FIG. 6 is a cross-sectional view of a score line 20 in a direction orthogonal to the longitudinal direction (toe-heel direction) and a partially enlarged view thereof. (A) is the schematic diagram which showed the example in the case of cutting a primary formation groove | channel by NC milling machine, (B) is an example of the cross-sectional shape of primary formation groove | channel 20 'formed in the 1st formation process. FIG. (A) is a figure which shows the example of a process at the time of using the cutting tool 4a which processes the notch 21 of the edge of both sides of primary formation groove | channel 20 'simultaneously, (B) shows the rotating shaft Z of the cutting tool 4b as a face. It is a figure which shows the example of a process in the case of processing the notch 21 inclining relatively with respect to the surface 10. FIG. (A) shows the measurement data of the score line of the Example of this invention, (B) shows the measurement data of the score line of a comparative example. The measured value of the groove width of the score line (groove width W1 in FIG. 2) when the edge angle of the primary groove (angle θ2 in FIG. 3B) and the notch angle θ1 (FIG. 2) are changed. It is a figure which shows evaluation of measurement, workability, and a test hit result.

Explanation of symbols

1 golf club head 10 face 20 score line 21 notch

Claims (4)

In the method of manufacturing a golf club head in which a plurality of score lines are formed on the face surface,
A first forming step of forming a groove to be a score line on the face surface;
A second forming step of cutting the edge of the groove formed in the first forming step, and forming a notch having an arcuate cross-sectional shape , one for each edge, in the longitudinal direction of the groove;
A method of manufacturing a golf club head comprising: In the second forming step,
While relatively moving the face surface or the cutting tool in the formation direction of the score line, the edge of the groove formed in the first forming step is cut with the cutting tool to form the notch,
2. The method of manufacturing a golf club head according to claim 1, wherein the formation of the groove and the formation of the notch are continuously performed by the same NC milling machine. The maximum cutting depth from the top of the edge by the cutting tool in the second forming step is 0.1 mm or less,
The golf club head manufacturing method according to claim 2, wherein a tip shape of the cutting tool in the second forming step has a curved surface that forms the notch. In a golf club head having a plurality of score lines formed on the face surface,
The score line after the groove which becomes the score lines are formed, are cut edge of the groove, the cross-sectional shape arcuate notches, one for each of the edges, longitudinally uniform of the groove A golf club head characterized in that it is formed.

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