JP5592065B2 - Golf club head - Google Patents

Description

  The present invention relates to a golf club head.

  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. 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.

  Patent Documents 1 and 2 disclose golf club heads in which a groove having a triangular cross section is formed on a face surface as a groove similar to a score line. Patent Documents 3 and 4 disclose golf club heads (putter heads) in which grooves having a triangular cross section are formed on the face surface. Patent Documents 5 and 6 disclose golf club heads in which a pad having a plurality of ribs is attached to a face surface. Patent Document 7 discloses a golf club head in which a groove smaller than the score line is formed on the face surface in addition to the score line.

U.S. Pat. No. 3,869,126 US Pat. No. 5,029,864 US Pat. No. 5,618,239 US Pat. No. 5,709,616 US Pat. No. 5,688,190 US Pat. No. 5,690,561 JP-A-9-253250

  There is a limit to increasing the backspin amount of the hit ball by devising the score line. Providing a groove different from the score line as in the golf club head of Patent Document 7 is effective in increasing the backspin amount of the hit ball. However, if a groove other than the score line is provided, the ball may be damaged.

  An object of the present invention is to provide a golf club head capable of obtaining a higher backspin amount while suppressing damage to the ball.

According to the present invention, in the golf club head in which a plurality of score lines are formed on the face surface, the golf club head includes a plurality of narrow grooves formed on the face surface and extending from the toe side to the heel side, The cross-sectional shape of the narrow groove is a triangle that is asymmetric with respect to a virtual center line in the width direction, and the minimum inner angle of three inner angles is a triangle positioned on the sole side of the golf club head, and the face the depth D from the surface to the deepest portion of the each of the fine grooves, Ri 10μm ≦ D ≦ 25 μm der, pitch P between the thin groove is a 100 [mu] m ≦ P ≦ 800 [mu] m, the fine of the face Provided is a golf club head characterized in that the arithmetic average roughness Ra of the groove-formed portion is 1.0 μm ≦ Ra ≦ 4.57 μm .

  According to the present invention, it is possible to provide a golf club head capable of obtaining a higher backspin amount while suppressing damage to the ball.

  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. The present invention is suitable for an iron type golf club head, particularly a middle iron, a short iron, and a wedge type golf club head. Specifically, the loft angle is 30 degrees or more and 70 degrees or less, and the head weight is 240 g or more. Suitable for golf club heads of 320 g or less. However, the present invention can also be applied to wood type or utility type (hybrid type) golf club heads.

  The golf club head 1 has a plurality of score lines 20 formed on its face surface (striking surface) 10. Each score line 20 is a linear groove extending in the toe-heel direction and parallel to each other. A plurality of narrow grooves 30 are formed on the face surface 10. In the present embodiment, the narrow groove 30 is a linear groove extending in the toe-heel direction parallel to the score line 20, but as an arc-shaped or elliptical arc-shaped groove extending in the toe-heel direction. Also good. FIG. 2 is a sectional view of the score line 20 and the narrow groove 30 in a direction perpendicular to the longitudinal direction (toe-heel direction) and an enlarged sectional view of the narrow groove 30. In the figure, a broken line 10 ′ indicates a virtual line on the same plane as the face surface 10. First, the score line 20 will be described.

  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. Further, in the present embodiment, the cross-sectional shape of the score line 20 is symmetric with respect to the virtual center line CLa in the width direction. The virtual center line CLa is a line that is orthogonal to the face surface 10 and passes through the midpoint of the width W of the score line 20. In the case of this embodiment, the cross-sectional shape of the score line 20 is trapezoidal, but other shapes such as a V shape may be used.

  The score line 20 has a pair of side surfaces 22 and a bottom surface 23. An edge 21 of the score line 20 is a boundary portion between the side surface 22 and the face surface 10. The edge 21 may be rounded. The angle θ is an angle formed by the side surface 22 and the face surface 10. The greater the angle θ, the higher the spin rate of the hit ball. The bottom surface 23 is parallel to the face surface 10. The depth D0 is a distance from the face surface 10 to the bottom surface 23 which is the deepest part of the score line 20. In the case of a competition golf club head, according to the rules, the depth D0 must be 0.020 inch (0.508 mm) or less.

  FIG. 3 is an explanatory diagram of the width W of the score line 20 and the distance S between the score lines 20 by the 30-degree measurement method. The width W means the width when measured by the so-called 30-degree measurement method of the rules of the competition golf club. That is, it means the distance between the contact points of the virtual line inclined by 30 degrees from the face surface 10 and the edge 21 of the score line 20. The distance S between the score lines 20 means the distance between the contact points of the imaginary line inclined 30 degrees from the face surface 10 and the edge 21 of the score line 20 in the adjacent score line 20.

In the case of a golf club head for competition, the cross-sectional area, width W, and distance S of the score line 20 need to be cross-sectional area A (inch ² ) / (W (inch) + S (inch)) ≦ 0.003 according to the rules. (Hereinafter referred to as area rule). In the case of a metric unit, the cross-sectional area A (mm ² ) / ( W (mm ) + S (mm )) ≦ 0.0762. When the golf club head 1 is a golf club head for competition, it is designed to satisfy the area rule. In addition, if it is designed so that the cross-sectional area A (inch ² ) / (W (inch) + S (inch)) ≦ 0.0025, the area rule can be more reliably met.

  As a rule regarding the score line of the golf club head for competition, in addition to the area rule, the rule is concentric with a virtual circle having a radius of 0.010 inch inscribed in the side surface and the face surface of the score line and having a radius of 0.011 inch. The edge of the score line must be located inside the virtual circle (hereinafter referred to as the two-circle rule).

  However, in order to satisfy the two-circle rule, the angle formed by the side surface of the score line and the face surface (the angle θ described above) must be reduced. In this case, not only the spin amount is reduced, but also the volume of the score line is reduced. Therefore, in the case of a shot from a rough or a shot in the rain, the spin amount may be significantly reduced.

  FIG. 4 is a diagram illustrating another example of the score line 20 (score line 20 ′). Hereinafter, regarding the score line 20 ′, the same components as those of the score line 20 are denoted by the same reference numerals, and the description thereof will be omitted, and only different components will be described.

  In FIG. 4, a virtual circle C1 is a circle having a radius of 0.01 inches inscribed in the side surface 22 and the face surface 10, and a virtual circle C2 is concentric with the virtual circle C1 and having a radius of 0.011 inches. It is. In order to conform to the above-described two-circle rule, the edge of the score line needs to be located inside the virtual circle C2.

  In the score line 20 ′, the flat surface 21 ′ is provided at the edge so that the two-circle rule is satisfied. In addition, as a shape of edge 21 ', roundness and a notch may be sufficient besides the flat surface 21a. When the golf club head 1 is a competition golf club head, it is designed to satisfy the two-circle rule.

  Next, the narrow groove 30 will be described with reference to FIG. In the case of the present embodiment, a large number of narrow grooves 30 are arranged at an equal pitch in a direction orthogonal to the longitudinal direction (direction orthogonal to the longitudinal direction of the score line 20). However, the pitch of the narrow grooves 30 may not be equal.

  The narrow groove 30 has a side surface 31 and a side surface 32. The cross-sectional shape of the narrow groove 20 is the same except for both end portions in the longitudinal direction. In the present embodiment, the cross-sectional shapes of the narrow grooves 30 are the same, but the narrow grooves 30 having different cross-sectional shapes may be combined.

  The cross-sectional shape of the narrow groove 30 defined by the side surface 31, the side surface 32, and the broken line 10 ′ indicating the face surface 10 is an asymmetric triangle with respect to the virtual center line CLb in the width Ws direction. The virtual center line CLb is a line that is orthogonal to the face surface 10 and passes through the midpoint of the width Ws of the narrow groove 30. The intersection of the side surface 31 and the side surface 32 may be rounded.

  A triangle which is a cross-sectional shape of the narrow groove 30 defined by the side surface 31, the side surface 32, and the broken line 10 ′ indicating the face surface 10 has three inner angles θ1 to θ3. The inner angle θ1 is an angle between the side surface 32 and the broken line 10 ′, the inner angle θ2 is an angle between the side surface 31 and the side surface 32, and the inner angle θ3 is an angle between the side surface 31. Of the three interior angles θ1 to θ3, the minimum interior angle θ1 that minimizes the angle is located on the sole side.

  In this way, the cross-sectional shape of the narrow groove 30 is a triangle that is asymmetric with respect to the virtual center line CLb in the width Ws direction, and the minimum inner angle θ1 is positioned on the sole side. The direction is more toward the sole side. When the golf club head 1 is driven into the golf ball so as to blow down, the side surface 31 is caught on the ball surface, and the backspin amount of the hit ball can be further increased.

  Thus, in the present embodiment, the backspin amount of the hit ball can be further increased by the narrow groove 30 in addition to the score line 20.

  The depth D is a distance from the face surface 10 to the deepest portion of the narrow groove 30. The deepest part is the intersection of the side surface 31 and the side surface 32, and the depth D is the length of the perpendicular from the broken line 10 'to the intersection of the side surface 31 and the side surface 32. When the depth D is deeper, the backspin amount of the hit ball becomes higher, but the hit ball is easily damaged. Therefore, the depth D is 40 μm or less. Further, when the depth D is made shallower, the hit ball is hardly damaged, but the effect of increasing the backspin amount is weakened. Therefore, the depth D is 10 μm or more.

  The pitch P is a distance between one end of the narrow groove 30 and one end of the adjacent narrow groove 30. When the pitch P and the width Ws are narrow, the narrow grooves 30 are likely to be clogged with grass and the like, and the backspin amount of the hit ball is reduced. When the pitch P and the width Ws are wide, the number of fine grooves 30 that come into contact with the golf ball at the time of impact is reduced, so that the backspin amount of the hit ball is reduced. Therefore, the pitch P and the width Ws are preferably 100 μm or more and 800 μm or less.

  The narrow grooves 30 may be formed continuously in the arrangement direction. FIG. 5 is a cross-sectional view of the narrow grooves 30 showing an example in which the narrow grooves 30 are continuously formed in the arrangement direction. In the example of the figure, adjacent narrow grooves 30 are connected without gaps and are formed continuously. In this case, the pitch P and the width Ws match.

  In the case of a short iron or a wedge, there are cases where the face is opened and a golf ball is shot so that backspin is easily applied. FIG. 6A shows a case where the face surface 10 is oriented perpendicular to the target direction, and FIG. 6B shows a case where the face surface 10 is opened. In FIG. 6A and FIG. 6B, the narrow groove 30 is not shown. 6A and 6B, the arrow indicates the relative movement direction of the golf ball B with respect to the face surface 10 at the time of hitting.

  When the face surface 10 is opened as shown in FIG. 6B, the golf ball B slides on the face surface 10 so as to cross the score line 20 and the narrow groove 30 obliquely at the time of hitting. When the direction orthogonal to the longitudinal direction of the narrow grooves 30 (that is, the arrangement direction) is more parallel to the direction indicated by the arrow in the figure, the number of the fine grooves 30 on which the golf ball B slides increases. The back spin is easily applied to the ball B. Therefore, the narrow grooves 30 may be crossed without being parallel to the score line 20.

  FIG. 7 is an external view of the golf club head 2 in which the narrow groove 30 intersects the score line 20. The golf club head 2 differs from the golf club head 1 only in the arrangement direction dr of the narrow grooves 30. In the example of the figure, the angle θr formed by the arrangement direction dr and the longitudinal direction of the score line 20 is about 45 degrees when viewed clockwise from the toe side of the score line 20. By setting the arrangement direction dr of the narrow grooves 30 in this way, it is possible to increase the backspin amount of the hit ball when the face surface 10 is opened.

  For example, the angle θr can be set in a range of 20 degrees or more and 90 degrees or less, and in the case of a short iron or a wedge, the face surface 10 is often opened. Therefore, the angle θr is preferably set in a range of 40 degrees or more and 70 degrees or less. .

  Next, the narrow groove 30 affects the surface roughness of the face surface 10. As indices of surface roughness, a maximum height (Ry) and an arithmetic average roughness (Ra) are known. The depth D is related to the maximum height (Ry). Further, the depth D, the width Ws, and the pitch P are related to the arithmetic average roughness (Ra). As the arithmetic average roughness (Ra) increases, the backspin amount of the hit ball becomes higher, but the hit ball is easily damaged. Accordingly, the arithmetic average roughness of the portion of the face surface 10 where the narrow grooves 30 are formed is preferably 5.0 μm or less. Also, the smaller the arithmetic average roughness (Ra), the harder it is to scratch, but the effect of increasing the backspin amount is weakened. Therefore, the arithmetic average roughness of the portion of the face surface 10 where the narrow grooves 30 are formed is preferably 1.0 μm or more, and more preferably 1.5 μm or more.

  In a golf club head for competition, the rule specifies that the surface roughness of the face surface is 4.57 μm or less in terms of arithmetic average roughness (Ra) and 25 μm or less in terms of the maximum height (Ry). When the golf club heads 1 and 2 are golf club heads for competition, they are designed to satisfy the rules for surface roughness.

  Specifically, the depth D is 10 μm or more and 25 μm or less. The arithmetic average roughness of the portion of the face surface 10 where the narrow grooves 30 are formed is 1.0 μm or more and 4.57 μm or less, and preferably 1.5 μm or more and 4.57 μm or less.

  As described above, in the competition golf club head, there are certain restrictions on the surface roughness of the score line 20 and the face surface, and it is not easy to increase the backspin amount after satisfying the rules. In the present embodiment, the cross-sectional shape of the narrow groove 30 is a triangle that is asymmetric with respect to the virtual center line CLb in the width Ws direction, and the normal direction of the side surface 31 is such that the minimum inner angle θ1 is located on the sole side. However, by making it point more toward the sole side, a higher backspin amount can be obtained even within the range of rule restrictions.

  Next, a method for forming the narrow groove 30 will be described. The fine groove 30 can be formed as a cutting trace by milling the face surface 10. The narrow groove 30 can be formed by milling using, for example, an NC (numerical control) milling machine. FIGS. 8A and 8B are explanatory views of a method for forming the narrow groove 30 using an NC milling machine.

  As shown in FIG. 8 (A), the golf club head 1 ′ with unprocessed narrow grooves 30 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 narrow groove 30 may be formed by fixing the face member to the NC milling machine. Further, although it is assumed that the golf club head 1 ′ has the score line 20 already formed, the narrow groove 30 may be formed before the score line 20 is formed.

  The NC milling machine has a spindle 4 that is driven to rotate about the Z axis, and a cutting tool (end mill) 5 is attached to the lower end of the spindle 4. The spindle 4 (that is, the Z axis) can be tilted. Further, as shown in FIG. 8B, the tip shape of the cutting tool 5 is in accordance with the cross-sectional shape of the narrow groove 30.

  In the NC milling machine, after setting the plane coordinates of the face surface 10, the spindle 4 is driven to rotate, and the face surface 10 (golf club head 1 ′) or the cutting tool 5 is relatively moved in the direction in which the narrow grooves 30 are formed. The face surface 10 is cut while moving. When one narrow groove 30 is formed, after the cutting tool 5 is separated from the face surface 10, the cutting tool 5 is relatively moved in the arrangement direction of the narrow grooves 30 to form the next narrow groove 30. Sequentially narrow grooves 30 are formed.

  As a method for forming the narrow groove 30, other forming methods such as electric discharge machining and casting can be adopted in addition to milling.

  Next, when the narrow groove 30 is formed on the face surface 10, the surface hardness of the face surface 10 may be lowered and may be easily worn. Therefore, after the formation of the narrow groove 30, it is preferable to perform a surface treatment for increasing the hardness of the face surface 10. Examples of such surface treatment include carburizing treatment, nitriding treatment, soft nitriding treatment, PVD (Physical Vepor Deposition) treatment, ion plating, DLC (diamond-like carbon) treatment, and plating treatment. In particular, surface treatment that modifies the surface without forming another metal layer on the surface, such as carburizing treatment or nitriding treatment, is preferable.

  Golf club heads # 1 to # 3 and # 11 to # 17 having different specifications and the presence or absence of fine grooves were prepared, and the backspin amount and the degree of damage to the hit ball were evaluated using the golf clubs equipped with these. FIG. 9 shows the conformity of the rules regarding the presence / absence and specifications of the narrow grooves of each golf club head # 1 to # 3 and # 11 to # 17, the evaluation result of the backspin amount and the hit state of the hit ball, and the surface roughness of the face surface. FIG.

  All golf club heads were sand wedges that differed only in the presence or absence of narrow grooves and the specifications. No narrow groove was formed for the # 1 golf club head, and narrow grooves were formed for the # 2 to # 3 and # 11 to # 17 golf club heads. A large number of narrow grooves were formed in parallel to the score line as in the golf club head 1 of FIG. 1 and were continuously formed in the arrangement direction as shown in FIG. Therefore, the width and pitch of the narrow groove coincide.

  In FIG. 9, “the position of the minimum internal angle” indicates which of the internal angles θ1 to θ3 illustrated in FIG. 2 is the minimum internal angle. “Upper side” in the golf club heads of # 2 and # 3 means that θ3 is the minimum inner angle in FIG. 2, that is, the cross-sectional shape of the narrow grooves of the golf club heads of # 2 and # 3 is shown in FIG. This corresponds to the one shown in FIG. “Sole side” in the golf club heads of # 11 to # 17 means that θ1 is the minimum inner angle in FIG. 2, that is, the cross-sectional shape of the narrow grooves of the golf club heads of # 11 to # 17 is shown in FIG. This corresponds to that shown in FIG.

  “Depth D” corresponds to the depth D in FIG. 2, in other words, the surface roughness (maximum height: Ry) of the face surface. “Pitch P” corresponds to the pitch P in FIG. 2, and as described above, the golf club heads of # 2 to # 3 and # 11 to # 17 have narrow grooves continuously formed in the arrangement direction. The pitch P is also the width of the narrow groove (Ws in FIGS. 2 and 5). “Surface roughness (Ra)” is the arithmetic average roughness of the face.

  The backspin amount and the degree of damage to the hit ball were evaluated by shooting a plurality of golf balls for one golf club from a rough about 30 yards away from the green. The “spin amount” in FIG. 9 was evaluated in five stages (A to E) by observing the ease of stopping of the hit ball on the green. A means that the hit ball was most easily stopped, that is, the backspin amount was large. “Damage” was evaluated by visually observing the scratches on the golf ball after the shot. “Rule conformance” indicates the conformity of the rule regarding the surface roughness of the face surface, and the arithmetic average roughness (Ra) is 4.57 μm or less and the maximum height (Ry) is 25 μm or less. (○) and non-conformity (×).

  From the comparison between the golf club head of # 1 and other golf club heads, it can be seen that the presence or absence of a narrow groove affects the backspin amount. Further, from comparison between the golf club heads # 2 and # 3 and the golf club heads # 11 to # 17, backspin is applied to the narrow groove having a cross-sectional shape in which the minimum inner angle is located on the sole side. It turns out that it is easy.

  Of the golf club heads # 11 to # 17, the golf club head # 13 has a high backspin amount, but the golf ball is slightly scratched. Therefore, the depth D is preferably 40 μm or less, and it is necessary to set the depth D to 25 μm or less in consideration of rule conformity. Further, the golf club head of # 11 does not have a very high backspin amount, and the effect of the narrow groove is thin. Therefore, the backspin amount can be further increased by setting the depth D to 10 μm or more.

  Focusing on the pitch P of the golf club heads of # 11 to # 17, the backspin amount is not so high in the golf club heads of # 14 and # 17 in the golf club heads of # 14 to # 17. Further, in the golf club heads of # 15 and # 16, a higher backspin amount is obtained. Therefore, the pitch P is preferably 100 μm or more and 800 μm or less, and more preferably 400 μm or more and 600 μm or less.

  When focusing on the surface roughness (Ra) of the golf club heads of # 11 to # 17, the larger the value, the higher the backspin amount. However, in the golf club head of # 13, the golf ball is slightly scratched. On the other hand, the golf club head of # 14 has almost no scratch. Accordingly, the surface roughness (Ra) is preferably 5.0 μm or less, and 4.57 μm or less in consideration of rule compatibility. Further, in the golf club head of # 17, the backspin amount is not so high. Therefore, the surface roughness (Ra) is preferably 1.0 μm or more.

1 is an external view of a golf club head 1 according to an embodiment of the present invention. 2 is a cross-sectional view of the score line 20 and the narrow groove 30 in a direction orthogonal to the longitudinal direction (toe-heel direction) and an enlarged cross-sectional view of the narrow groove 30. It is explanatory drawing of the distance S between the width W of the score line 20 and the score line 20 by a 30 degree | times measuring method. It is a figure which shows the other example (score line 20 ') of the score line 20. FIG. It is sectional drawing of the fine groove 30 which shows the example which formed the fine groove 30 continuously in the sequence direction. (A) shows the case where the face surface 10 is oriented perpendicular to the target direction, and (B) shows the case where the face surface 10 is opened. 1 is an external view of a golf club head 2 in which a narrow groove 30 intersects a score line 20. FIG. (A) And (B) is explanatory drawing of the formation method of the fine groove 30 by NC milling machine. It is a figure which shows the rule conformity regarding the presence or absence of a narrow groove of each golf club head # 1 to # 3 and # 11 to # 17, the evaluation result of the backspin amount and the hit state of the hit ball, and the surface roughness of the face surface. is there.

Explanation of symbols

1 golf club head 10 face 20 score line 30 narrow groove

Claims (6)

In a golf club head having a plurality of score lines formed on the face surface,
A plurality of narrow grooves formed on the face surface and extending from the toe side to the heel side;
The cross-sectional shape of each narrow groove is
A triangle that is asymmetric with respect to the virtual center line in the width direction, the smallest inner angle of the three inner angles being a triangle located on the sole side of the golf club head,
A depth D from the face surface to the deepest part of each narrow groove is:
10 μm ≦ D ≦ 25 μm
Der is,
The pitch P between the narrow grooves is
100 μm ≦ P ≦ 800 μm
And
Arithmetic average roughness Ra of the portion where the narrow groove of the face surface is formed,
1.0 μm ≦ Ra ≦ 4.57 μm
A golf club head characterized by the above. A face member constituting the face surface;
A head body which is a member different from the face member to which the face member is joined;
The golf club head according to claim 1, further comprising: The narrow groove is
A first side surface continuous with the face surface at one end;
A second side surface that is continuous with the first side surface at one end and is continuous with the face surface at the other end;
The golf club head according to claim 1, wherein a boundary portion between the first side surface and the second side surface is rounded. The narrow groove is
A first side surface continuous with the face surface at one end;
A second side surface that is continuous with the first side surface at one end and is continuous with the face surface at the other end;
The golf club head according to claim 1, wherein an inner angle between the first side surface and the face surface is less than 90 degrees. A cross-sectional area A (inch ² ) of the score line, a width W (inch) of the score line measured by a 30-degree measurement method, and a distance S (inch) of the adjacent score lines,
A / (W + S) ≦ 0.003
And
The edge of the score line
It is formed so as to be concentric with a first imaginary circle having a radius of 0.010 inches inscribed in a side surface of the score line and the face surface, and to be located inside a second imaginary circle having a radius of 0.011 inches. The golf club head according to claim 1, wherein: A cross-sectional area A (inch ² ) of the score line, a width W (inch) of the score line measured by a 30-degree measurement method, and a distance S (inch) of the adjacent score lines,
A / (W + S) ≦ 0.0025
And
The edge of the score line
It is formed so as to be concentric with a first imaginary circle having a radius of 0.010 inches inscribed in a side surface of the score line and the face surface, and to be located inside a second imaginary circle having a radius of 0.011 inches. The golf club head according to claim 1, wherein:

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