Golf club heads and golf clubs

Abstract

To provide a golf club head that can suppress toe-down and offers superior distance performance. [Solution] The head 4 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The crown portion 12 has a projection 20 on the outer surface 12a of the crown. In a front view of the head 4 as seen from the face side, the projection 20 does not constitute the outer contour line CL1 of the head 4. In a heel projection view of the head 4 as seen from the heel side along the ground plane HP, with the shaft axis Z perpendicular to the ground plane HP and the face angle at 0 degrees, the projection 20 constitutes the outer contour line CL6 of the head 4. With this head 4, drag and lift can be increased at position 9. With this head 4, air resistance can be suppressed at position 6.

Description

[Technical Field]

[0001] This disclosure relates to golf club heads and golf clubs. [Background technology]

[0002] Known specifications that are advantageous for increasing distance include larger heads, longer club lengths, and softer shafts that increase flex. Furthermore, by reducing the shaft weight without reducing the head weight, it's possible to achieve a club that is both easy to swing and has high rebound performance.

[0003] On the other hand, one of the factors that hinders flight distance is the toe-down phenomenon. Japanese Patent Publication No. 11-267251 and Japanese Patent Publication No. 10-43332 disclose information regarding the toe-down phenomenon. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-267251 [Patent Document 2] Japanese Patent Application Publication No. 10-43332 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] It has been found that specifications that are advantageous for distance can increase toe-down. In conventional golf clubs, there is a trade-off between suppressing toe-down and increasing distance, and it has been difficult to achieve both.

[0006] One of the purposes of this disclosure is to provide a golf club head that can suppress toe-down and has excellent distance performance. [Means for solving the problem]

[0007] In one embodiment, the golf club head includes a face portion that forms the striking face, a crown portion that forms the outer surface of the crown, a sole portion that forms the outer surface of the sole, and a hosel portion to which the shaft is attached and which defines the shaft axis. The crown portion has a projection on its outer surface. In a front view of the head as seen from the face side, the projection does not constitute the outer contour of the head. In a heel projection view of the head as seen from the heel side along the ground plane, with the shaft axis perpendicular to the ground plane and the face angle at 0 degrees, the projection constitutes the outer contour of the head. [Effects of the Invention]

[0008] One aspect of this design is that it can provide a golf club head with suppressed toe-down and superior distance performance. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows a golf club according to the first embodiment. [Figure 2] Figure 2(a) is a front view of the head of the first embodiment, seen from the face side, showing the head in the standard state. Figure 2(b) is a view of the head of the first embodiment in the heel projection position, seen from the face side. [Figure 3] Figure 3 is a plan view of the head of the first embodiment, as seen from the crown side. [Figure 4] Figure 4 is a side view of the head of the first embodiment, as seen from the heel side. [Figure 5] Figure 5 is a view of the head of the first embodiment from the inclined heel side. Figure 5 is a heel projection view. [Figure 6] Figure 6 shows a portion of the outer contour line of the head of the first embodiment, viewed from the toe and back directions. [Figure 7] Figure 7 shows the cross-sectional line of the outer surface of the head in the cross-sectional view along line AA in Figure 3. [Figure 8] Figure 8 shows the cross-sectional line of the outer surface of the head in the cross-sectional view along line BB in Figure 3. [Figure 9] Figure 9 shows the cross-section line of the outer surface of the head in the cross-sectional view taken along the line C-C in Figure 3. [Figure 10] Figure 10 shows the cross-section line of the outer surface of the head in the cross-sectional view taken along the line D-D in Figure 3. [Figure 11] Figure 11 is an enlarged view of the portion surrounded by the square line Q1 in Figure 7. In Figure 11, the virtual extension line of the crown base surface is added. [Figure 12] Figure 12 is an enlarged view of the portion surrounded by the square line Q2 in Figure 9. In Figure 12, the virtual extension line of the crown base surface is added. [Figure 13] Figure 13(a) is a figure with the heel projection view of Figure 5 as a silhouette. Figure 13(b) shows a part of the contour line of this silhouette. Figure 13(b) is a part of the outer contour line of the heel projection view of the head in the first embodiment. [Figure 14] Figure 14 is a plan view of the head in the second embodiment as seen from the crown side. [Figure 15] Figure 15 is a plan view of the head in the third embodiment as seen from the crown side. [Figure 16] Figure 16 is a plan view of the head in the fourth embodiment as seen from the crown side. [Figure 17] Figure 17 is a plan view of the head in the fifth embodiment as seen from the crown side. [Figure 18] Figure 18 is a plan view of the head in the sixth embodiment as seen from the crown side. [Figure 19] Figure 19(a) shows a part of the outer contour line of the head in the seventh embodiment when viewed from the toe side and the back side direction. Figure 19(b) shows a part of the outer contour line of the head in the eighth embodiment when viewed from the toe side and the back side direction. [Figure 20] Figure 20(a) is a perspective view of the head in the ninth embodiment, and Figure 20(b) is a cross-sectional view taken along the line b-b in Figure 20(a). The description of the cross-section of the head body is omitted in Figure 20(b). [Figure 21]Figure 21(a) is a perspective view of the head body of the ninth embodiment, and Figure 21(b) is a cross-sectional view along line bb in Figure 21(a). In Figure 21(b), the cross-sectional view of the head body is omitted. [Figure 22] Figure 22(a) is a perspective view of the head of the tenth embodiment, Figure 22(b) is a cross-sectional view along line bb in Figure 22(a), and Figure 22(c) is a cross-sectional view along line cc in Figure 22(a). In Figures 22(b) and 22(c), the cross-section of the head body is omitted. [Figure 23] Figure 23(a) is a perspective view of the head body of the head of the 10th embodiment, Figure 23(b) is a cross-sectional view along line bb in Figure 23(a), and Figure 23(c) is a cross-sectional view along line cc in Figure 23(a). In Figures 23(b) and 23(c), the cross-section of the head body is omitted. [Figure 24] Figure 24 shows the movement of the golf club during the downswing. [Figure 25] Figures 25(a) and 25(b) are conceptual diagrams illustrating the forces acting on a head without protrusions at position 9. Figure 25(c) is a conceptual diagram showing the position of this head at impact. [Figure 26] Figures 26(a) and 26(b) are conceptual diagrams illustrating the forces acting on the head with a protrusion at position 9. Figure 26(c) is a conceptual diagram showing the position of this head at impact. [Figure 27] Figure 27(a) shows the average head speed (H / S) for testers 1 through 9. The left side of the bar graph shows the results for club A (no protrusion), and the right side shows the results for club B (with protrusion). Figure 27(b) shows the average distance between the point of impact and the face center for testers 1 through 9. The left side of the bar graph shows the results for club A (no protrusion), and the right side shows the results for club B (with protrusion). [Figure 28]Figure 28(a) shows the average face angle for testers 1 through 9. The left side of the bar graph represents the results for club A, and the right side represents the results for club B. Figure 28(b) shows the average smash factor for testers 1 through 9. The smash factor is calculated by dividing the ball speed (B / S) by the club head speed (H / S). The left side of the bar graph represents the results for club A, and the right side represents the results for club B. [Figure 29] Figure 29(a) shows the standard deviation of head speed (H / S) for testers 1 through 9. The left side of the bar graph represents the results for club A, and the right side represents the results for club B. Figure 29(b) shows the standard deviation of the distance between the point of impact and the face center for testers 1 through 9. The left side of the bar graph represents the results for club A, and the right side represents the results for club B. [Figure 30] Figure 30 shows the standard deviation of face angle for testers 1 through 9. The left side of the bar graph represents the results for club A, and the right side represents the results for club B. [Figure 31] Figure 31 is a conceptual diagram illustrating the reference state. [Modes for carrying out the invention]

[0010] (Knowledge that forms the basis of this disclosure) The toe-down phenomenon occurs because the head's center of gravity is located away from the shaft axis. During a swing, centrifugal force acts on the head's center of gravity. As shown in Figure 1, the head's center of gravity CG is located to the toe side of the shaft axis Z. Therefore, due to the centrifugal force, the shaft bends so that the toe side of the head drops down. Also, as shown in Figure 4, the head's center of gravity CG is located to the back side of the shaft axis Z. Therefore, due to the centrifugal force, the shaft bends so that the back side of the head drops down. In short, due to the centrifugal force, the shaft bends and twists so that the toe and back sides of the head drop down. The shaft bends so that the toe side of the head drops down and twists in the direction that the face opens. This is the toe-down phenomenon. The greater the centrifugal force, the greater the toe-down. Also, the further the head's center of gravity is from the shaft axis, the greater the toe-down.

[0011] As described above, due to centrifugal force, the toe side of the club head and the back side of the club head both drop down. These phenomena can be explained separately as toe-down and back-down, but in this application, they are collectively referred to as toe-down.

[0012] One way to suppress toe-down is to shorten the club length. However, in this case, the kinetic energy of the club head decreases, resulting in a decrease in distance. Another way to suppress toe-down is to lighten the weight of the club head. However, in this case as well, the kinetic energy of the club head decreases, resulting in a decrease in distance.

[0013] To suppress toe-down, one might consider shortening the center of gravity distance and / or making the center of gravity depth shallower. However, in this case, the high-rebound area becomes smaller, and the average distance decreases. Also, the face direction becomes unstable, which further reduces the average distance.

[0014] To suppress toe-down, one might consider increasing the bending rigidity of the shaft tip. However, in this case, the trajectory will be lower, and the distance will decrease.

[0015] To reduce the effects of toe-down, one might consider making the lie angle more upright or using a hook face. However, golf clubs with an upright lie angle and a hook face are difficult to address.

[0016] Golf clubs designed for ease of swinging increase head speed. However, this increased head speed increases the centrifugal force acting on the center of gravity of the club head, resulting in greater toe-down.

[0017] Thus, factors that increase distance can increase toe-down. Excessive toe-down worsens the impact point or the angle of impact with the club head. Furthermore, in situations with excessive toe-down, the amount of toe-down tends to vary, and the impact point or the angle of impact with the club head is unstable. Therefore, energy loss at impact is likely to occur due to toe-down.

[0018] Thus, it was found that even if a golf club has elements that increase distance, excessive toe-down reduces that distance. The inventors of this invention have discovered that by suppressing toe-down using a method different from conventional methods, it is possible to achieve both suppression of toe-down and improved distance performance.

[0019] The present disclosure will be described in detail below, with reference to drawings as appropriate, based on preferred embodiments.

[0020] In this application, the following are defined: reference state, reference vertical plane, toe-heel direction, face-back direction, vertical direction, face center, heel projection orientation, inclined toe-heel direction, and heel projection diagram.

[0021] The standard state is defined as the state in which the club head is placed on the ground plane HP at a predetermined lie angle. As shown in Figure 31, in this standard state, the shaft axis Z is contained within the plane VP perpendicular to the ground plane HP. The shaft axis Z is the center line of the shaft. The plane VP is defined as the standard vertical plane. The predetermined lie angle is listed, for example, in the product catalog.

[0022] In this standard state, the face angle is considered to be 0 degrees. That is, in a plan view from above, the tangent line at the face center of the striking face is considered to be parallel to the toe-heel direction. The definitions of the face center and the toe-heel direction are described below.

[0023] In this application, the toe-heel direction is the direction of the intersection line NL between the reference vertical plane VP and the ground plane HP (see Figure 31).

[0024] In this application, the face-back direction is the direction perpendicular to the toe-heel direction and parallel to the ground plane HP. The face side in the face-back direction is also simply referred to as the "face side." The back side in the face-back direction is also simply referred to as the "back side."

[0025] In this application, the vertical direction is the direction perpendicular to the toe-heel direction and perpendicular to the face-back direction. In other words, in this application, the vertical direction is the direction perpendicular to the ground plane HP.

[0026] In this application, the face center is determined as follows: First, an arbitrary point Pr is selected near the approximate center of the striking face in the vertical and toe-heel directions. Next, a plane is determined that passes through this point Pr, extends along the normal direction of the striking face at point Pr, and is parallel to the toe-heel direction. A line is drawn between this plane and the striking face, and its midpoint Px is determined. Next, a plane is determined that passes through this midpoint Px, extends along the normal direction of the striking face at point Px, and is parallel to the vertical direction. A line is drawn between this plane and the striking face, and its midpoint Py is determined. Next, a plane is determined that passes through this midpoint Py, extends along the normal direction of the striking face at point Py, and is parallel to the toe-heel direction. A line is drawn between this plane and the striking face, and its midpoint Px is newly determined. Next, a plane is determined that passes through this new midpoint Px, extends along the normal direction of the striking face at point Px, and is parallel to the vertical direction. A line is drawn at the intersection of this plane and the hitting face, and the midpoint Py is newly determined. This process is repeated to sequentially determine Px and Py. In the repetition of this process, the new position Py (the last position Py) at which the distance between the new midpoint Py and the immediately preceding midpoint Py becomes 0.5 mm or less is the face center.

[0027] The heel projection position is the state where the shaft axis Z is perpendicular to the ground plane HP and the face angle is 0 degrees. This heel projection position is shown in Figures 2(b) and 5. In the heel projection position, the heel side of the sole is far away from the ground plane HP, and the toe side or the toe side (skirt) of the sole is in contact with the ground plane HP. The heel projection position is achieved by rotating the head in the standard state until the shaft axis Z is perpendicular to the ground plane HP. This rotation causes the toe-heel direction of the head to tilt relative to the ground plane HP (see Figure 2(a)). However, in a plan view from above, this rotation does not change the toe-heel direction. That is, the face angle remains 0 degrees in the heel projection position.

[0028] The vector of the head along the toe-heel direction in the heel projection position can be decomposed into a vector V1 parallel to the ground plane HP and a vector V2 perpendicular to the ground plane HP (see Figure 2(b)). The direction of vector V1 parallel to the ground plane HP is defined as the inclined toe-heel direction. The inclined toe-heel direction is perpendicular to the shaft axis Z. The heel side in the inclined toe-heel direction is also called the inclined heel side. The toe side in the inclined toe-heel direction is also called the inclined toe side. In Figure 2(b), the inclined heel direction is labeled S-heel and the inclined toe direction is labeled S-toe.

[0029] A heel projection diagram is a projection of a head in a heel projection position, viewed from the heel side along the ground plane HP. In other words, a heel projection diagram is a projection of a head in a heel projection position along the inclined toe-heel direction towards the heel side. Figure 5 is a heel projection diagram.

[0030] Figure 1 is an overall view of a golf club 2 including a head 4 according to one embodiment of the present disclosure. Figure 2(a) is a front view of the head 4. Figure 2(a) is a view of the head 4 in the reference state as seen from the face side. Figure 2(b) is a view of the head 4 in the heel projection position as seen from the face side. Figure 3 is a plan view of the head 4 as seen from the crown side. Figure 4 is a side view of the head 4 as seen from the heel side. Figure 5 is a view of the head 4 as seen from the inclined heel side. Figure 5 is a heel projection view of the head 4.

[0031] As shown in Figure 1, the golf club 2 includes a golf club head 4, a shaft 6, and a grip 8. The shaft 6 has a tip end Tp and a butt end Bt. The head 4 is attached to the tip end of the shaft 6. The grip 8 is attached to the butt end of the shaft 6.

[0032] Golf club 2 is a driver (1-wood). Typically, the club length of a driver is 43 inches or longer. Preferably, golf club 2 is a wood-type golf club.

[0033] The shaft 6 is tubular. The shaft 6 has a hollow structure. The material of the shaft 6 is carbon fiber reinforced resin. From the viewpoint of weight reduction, carbon fiber reinforced resin is preferred as the material of the shaft 6. The shaft 6 is a so-called carbon shaft. Preferably, the shaft 6 is made by curing a prepreg sheet. In this prepreg sheet, the fibers are substantially oriented in one direction. A prepreg in which the fibers are substantially oriented in one direction in this way is also called a UD prepreg. "UD" is an abbreviation for unidirection. Prepregs other than UD prepregs may be used. For example, the fibers contained in the prepreg sheet may be woven. The shaft 6 may contain metal wires. The material of the shaft 6 is not limited and may be, for example, metal.

[0034] Grip 8 is the part that is held by the golfer during the swing. Examples of materials for grip 8 include rubber compositions and resin compositions. The rubber composition of grip 8 may contain air bubbles.

[0035] Although not shown, head 4 has a hollow structure. In this embodiment, head 4 is wood-type. Head 4 may also be hybrid-type (utility-type). Head 4 may also be iron-type. Head 4 may also be putter-type. Preferred materials for head 4 include metal and fiber-reinforced plastic. Examples of metals include titanium alloy, pure titanium, stainless steel, maraging steel, and soft iron. An example of fiber-reinforced plastic is carbon fiber reinforced plastic. Head 4 may also be a composite head having a metal portion and a fiber-reinforced plastic portion.

[0036] As shown in Figures 2 to 5, the head 4 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The striking face 10a is also simply called the face. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a.

[0037] As shown in Figures 1 and 4, the head 4 has a center of gravity CG. In this embodiment, the head center of gravity CG is located inside the head 4 (hollow portion).

[0038] In Figure 1, the double arrow B indicates the distance to the center of gravity of head 4. The distance to the center of gravity B is the distance between the shaft axis Z and the center of gravity CG of the head. The distance to the center of gravity B is not an actual three-dimensional distance, but a distance in a front view of head 4. In the head in the reference state, the shaft axis Z and the center of gravity CG of the head are projected onto the reference vertical plane VP. The distance to the center of gravity B is the distance in this projected image.

[0039] In Figure 4, the double-headed arrow C indicates the center of gravity depth of head 4. The center of gravity depth C is the distance between the shaft axis Z and the head's center of gravity CG. The center of gravity depth C is measured along the face-back direction.

[0040] The striking face 10a has a face center Fc as defined above.

[0041] The head's center of gravity CG of head 4 is not on the shaft axis Z. The head's center of gravity CG is away from the shaft axis Z. Head 4 has a center of gravity distance B and a center of gravity depth C. The presence of the center of gravity distance B and center of gravity depth C causes the toe-down phenomenon.

[0042] The crown portion 12 has a projection 20 on the outer surface 12a of the crown. The projection 20 is hollow. The projection 20 forms a convex shape on the outer surface 12a of the crown and a concave shape on the inner surface of the crown.

[0043] In the front view of the head as seen from the face side (Figure 2(a)), the protrusion 20 is not visible. In the front view of the head as seen from the face side (Figure 2(a)), the protrusion 20 does not constitute the outer contour line CL1 of the head 4.

[0044] In this embodiment, the entire projection 20 is provided on the outer surface 12a of the crown. As shown in Figure 3, the head 4 has an outer contour line CL2 in the plan view of the head 4. As shown in Figure 3, the projection 20 does not reach the outer contour line CL2. The projection 20 does not extend to any part other than the outer surface 12a of the crown.

[0045] The plan view of head 4 is a projection of the head in its standard state onto a plane parallel to the ground plane HP. This plan view (Figure 3) is also called a plan view.

[0046] In the plan view of head 4 (Figure 3), the protrusion 20 may reach the outer contour line CL2. In other words, the protrusion 20 may form the outer contour line CL2. The protrusion 20 may extend to parts other than the outer surface 12a of the crown. For example, the protrusion 20 may extend from the outer surface 12a of the crown to the outer surface 14a of the sole. For example, the protrusion 20 may extend from the outer surface 12a of the crown to the outer surface of the side portion (skirt portion).

[0047] In the side view (Figure 4) of the standard head 4, viewed from the heel side in the toe-heel direction, the entire protrusion 20 is visible. This side view has the outer contour line CL3 of the crown outer surface 12a. In this side view, the protrusion 20 does not reach the outer contour line CL3. The entire protrusion 20 is located on the heel side of the face center Fc. A portion of the protrusion 20 may extend beyond the face center Fc towards the toe side.

[0048] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protruding portion 20 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex surface. This convex surface is convex toward the outside of the head 4. As shown in Figure 3, the crown base surface 12b contains the centroid CR of the plan view of the head 4. The centroid CR is the centroid of the figure formed by the outer contour line CL2.

[0049] Figure 6 shows a portion of the outer contour line of head 4 as viewed from the toe side. Figure 7 shows the cross-sectional line of the outer surface of head 4 in a cross-sectional view along line AA in Figure 3. Figure 8 shows the cross-sectional line of the outer surface of head 4 in a cross-sectional view along line BB in Figure 3. Figure 9 shows the cross-sectional line of the outer surface of head 4 in a cross-sectional view along line CC in Figure 3. Figure 10 shows the cross-sectional line of the outer surface of head 4 in a cross-sectional view along line DD in Figure 3. Figures 7 to 10 include the cross-sectional line of the crown outer surface 12a.

[0050] The projection 20 has a contour line CL20, an upper surface 22, and a side wall surface 24. The contour line CL20 is the boundary line between the crown base surface 12b and the projection 20. In the plan view of the head 4 (Figure 3), the contour line CL20 of the projection 20 is approximately quadrilateral (approximately trapezoidal). In this application, "approximately" includes configurations where the sides are curved (not straight) or where the corners are rounded. In the contour line CL20 in the plan view of the head (Figure 3), the radius of curvature of the sides is preferably 25 mm or more, more preferably 40 mm or more, and more preferably 50 mm or more. In the contour line CL20 in the plan view of the head (Figure 3), the radius of curvature of the corners is preferably 10 mm or less, more preferably 7 mm or less, and more preferably 5 mm or less. The contour line CL20 forms an approximately quadrilateral.

[0051] The upper surface 22 and the side wall surface 24 may be demarcated by a ridge line. In the cross-sectional line of the outer surface of the protruding portion 20, this ridge line may be identified as a point with a radius of curvature of 5 mm or less, or as the vertex of a bend. The radius of curvature of this cross-sectional line may vary depending on the direction of the cross section, but in determining the radius of curvature for defining the ridge line, a cross section is selected that minimizes the radius of curvature.

[0052] In the plan view of head 4, the projection 20 may be approximately polygonal. When this approximately polygonal is approximately N-sided, N may be an integer of 3 or more. N may also be an integer between 3 and 20.

[0053] The contour line CL20 has a first side CL21, a second side CL22, a third side CL23, and a fourth side CL24. The first side CL21 constitutes the toe-side and face-side side of the protruding portion 20. The first side CL21 extends towards the back as it moves towards the toe. The first side CL21 connects the second side CL22 and the fourth side CL24.

[0054] The second side CL22 constitutes the heel-side and face-side side of the protruding portion 20. The second side CL22 extends towards the back as it approaches the heel. The second side CL22 connects the first side CL21 and the third side CL23.

[0055] The third side CL23 constitutes the heel-side and back-side of the protruding portion 20. The third side CL23 extends towards the back as it approaches the toe side. The third side CL23 connects the second side CL22 and the fourth side CL24. The third side CL23 is a convex curve towards the outside of the head 4.

[0056] The fourth side CL24 constitutes the toe-side and back-side edge of the protruding portion 20. The fourth side CL24 extends towards the back as it approaches the heel. The fourth side CL24 connects the third side CL23 and the first side CL21.

[0057] The second side CL22, the third side CL23, and the fourth side CL24 each serve as the base points of the side wall surface 24. That is, the second side CL22, the third side CL23, and the fourth side CL24 each constitute the boundary line between the side wall surface 24 and the crown base surface 12b. On the other hand, the first side CL21 does not serve as the base point of the side wall surface 24. The first side CL21 constitutes the boundary line between the crown base surface 12b and the top surface 22.

[0058] In this application, the section line along the toe-heel direction is also simply referred to as the cross section line. Figure 7 is an example of a cross section line. The cross section line of the outer surface 12a of the crown is also referred to as the crown cross section line. Figure 7 includes the crown cross section line. In this application, the section line along the face-back direction is also simply referred to as the longitudinal section line. Figure 9 is an example of a longitudinal section line. The longitudinal section line of the outer surface 12a of the crown is also referred to as the crown longitudinal section line. Figure 9 includes the crown longitudinal section line.

[0059] An inflection point in the crown cross-section can be a point that constitutes the contour line CL20. In other words, this inflection point can be the starting point of the projection 20. The cross-section of the crown base surface 12b is a curve that is convex toward the outside of the head 4. The inflection point is the point where the curve that is convex toward the outside of the head 4 changes to a curve that is convex toward the inside of the head 4.

[0060] The vertex of the bend in the crown cross-section can become a point that constitutes the contour line CL20. In other words, this vertex can be the starting point of the projection 20. The cross-section of the crown base surface 12b is a curve that is convex toward the outside of the head 4. The line that connects to this curve and bends upward forms a vertex. This vertex is a vertex that faces toward the inside of the head 4. This vertex can be the starting point of the projection 20.

[0061] An inflection point in the crown's longitudinal section line can be a point that constitutes the contour line CL20. In other words, this inflection point can be the starting point of the projection 20. The longitudinal section line of the crown base surface 12b is a curve that is convex toward the outside of the head 4. The inflection point is the point where the curve that is convex toward the outside of the head 4 changes to a curve that is convex toward the inside of the head 4.

[0062] The vertex of the bend in the crown's longitudinal section line can become a point that constitutes the contour line CL20. In other words, this vertex can be the starting point of the projection 20. The longitudinal section line of the crown base surface 12b is a curve that is convex toward the outside of the head 4. The line that connects to this curve and bends upward forms a vertex. This vertex is a vertex that faces toward the inside of the head 4. This vertex can be the starting point of the projection 20.

[0063] Typically, the contour line CL20 can be determined by the inflection point or vertex. In selecting the section line for this determination, the crown cross section line may be preferred over the crown longitudinal section line. In this case, the crown cross section line is used to identify the inflection point or vertex. If identification using the crown cross section line is difficult, the crown longitudinal section line may be used. The contour line of a clearly visible projection 20 can be considered as the contour line CL20.

[0064] The protrusion 20 is a portion that protrudes beyond the crown base surface 12b. Below the protrusion 20, a virtual extension surface 12c may be identified, which is an extension of the crown base surface 12b. The protrusion 20 is a portion that protrudes beyond the virtual extension surface 12c. The virtual extension surface 12c can be considered as the crown base surface 12b that would be formed in the area where the protrusion 20 is installed if it were not present. The virtual extension surface 12c is formed continuously with the crown base surface 12b. The virtual extension surface 12c is a curved surface that is convex outward from the head 4. The virtual extension surface 12c is smoothly connected to the crown base surface 12b.

[0065] Figure 11 is an enlarged view of the area enclosed by the rectangle Q1 in Figure 7. Figure 12 is an enlarged view of the area enclosed by the rectangle Q2 in Figure 9.

[0066] The crown cross-sectional line in Figure 11 shows virtual extension lines 12d that can constitute the virtual extension surface 12c. The virtual extension line 12d is a curve that is convex outward from the head 4. The virtual extension line 12d smoothly connects to the cross-sectional line of the crown base surface 12b. The virtual extension surface 12c can be formed by a collection of virtual extension lines 12d.

[0067] The virtual extension line 12d smoothly connects the cross-sectional line on one side of the projection 20 to the cross-sectional line on the other side of the projection 20. The virtual extension line 12d can be drawn as a Bézier curve. Two types of Bézier curves are known: quadratic Bézier curves and cubic Bézier curves. A quadratic Bézier curve has one control point. A cubic Bézier curve has two control points. Preferably, a cubic Bézier curve is used. The Bézier curves in Figures 11 and 12 are cubic Bézier curves.

[0068] As shown in Figure 11, the crown cross section has a first starting point P1 and a second starting point P2. The first starting point P1 and the second starting point P2 are points on the contour line CL20.

[0069] To define the effective tangent at the first starting point P1, points P11 and P12 are determined on the opposite side of the first starting point P1 from the projection 20. Point P11 is 0.5 mm away from the first starting point P1. Point P12 is 0.5 mm away from point P11. These 0.5 mm distances are the distances along the crown cross-section line. Points P11 and P12 are points on the crown cross-section line. The tangent line L1 at point P1 to the circle passing through the three points P1, P11, and P12 is determined. If points P1, P11, and P12 are collinear, this line can be considered the tangent line L1.

[0070] Similarly, to define the effective tangent at the second starting point P2, points P21 and P22 are determined on the opposite side of the second starting point P2 from the projection 20. Point P21 is 0.5 mm away from the second starting point P2. Point P22 is 0.5 mm away from point P21. These 0.5 mm distances are the distances along the crown cross-section line. Points P21 and P22 are points on the crown cross-section line. The tangent line L2 at point P2 to the circle passing through the three points P2, P21, and P22 is determined. If points P2, P21, and P22 are collinear, this line can be considered the tangent line L2.

[0071] Once the tangents L1 and L2 are determined, the intersection point Px of tangents L1 and L2 is determined. Furthermore, the midpoint M1 between point P1 and point Px is determined, and the midpoint M2 between point P2 and point Px is determined.

[0072] A Bézier curve can be drawn starting at point P1, with midpoint M1 as the first control point, midpoint M2 as the second control point, and point P2 as the endpoint. In Figure 11, this Bézier curve is the virtual extension line 12d. Since there are two control points, this Bézier curve is a cubic Bézier curve.

[0073] A virtual extension line 12d can be defined at any position in the face-back direction. A virtual extension plane 12c can be defined by the set of these virtual extension lines 12d.

[0074] A similar Bézier curve can be defined for the crown longitudinal section line. As shown in Figure 12, the crown longitudinal section line has a first starting point P1 and a second starting point P2. The first starting point P1 and the second starting point P2 are points on the contour line CL20.

[0075] To define the effective tangent at the first starting point P1, points P11 and P12 are determined on the opposite side of the first starting point P1 from the projection 20. Point P11 is 0.5 mm away from the first starting point P1. Point P12 is 0.5 mm away from point P11. These 0.5 mm distances are the distances along the crown longitudinal section line. Points P11 and P12 are points on the crown longitudinal section line. The tangent line L1 at point P1 to the circle passing through the three points P1, P11, and P12 is determined. If points P1, P11, and P12 are collinear, this line can be considered the tangent line L1.

[0076] Similarly, to define the effective tangent at the second starting point P2, points P21 and P22 are determined on the opposite side of the second starting point P2 from the projection 20. Point P21 is 0.5 mm away from the second starting point P2. Point P22 is 0.5 mm away from point P21. These 0.5 mm distances are the distances along the crown longitudinal section line. Points P21 and P22 are points on the crown longitudinal section line. The tangent line L2 at point P2 to the circle passing through the three points P2, P21, and P22 is determined. If points P2, P21, and P22 are collinear, this line can be considered the tangent line L2.

[0077] Once the tangents L1 and L2 are determined, the intersection point Px of tangents L1 and L2 is determined. Furthermore, the midpoint M1 between point P1 and point Px is determined, and the midpoint M2 between point P2 and point Px is determined.

[0078] A Bézier curve can be drawn using point P1 as the starting point, midpoint M1 as the first control point, midpoint M2 as the second control point, and point P2 as the ending point. In Figure 12, this Bézier curve is the virtual extension line 12e.

[0079] A virtual extension line 12e can be defined at any position in the toe-heel direction. A virtual extension plane 12c can be defined by the set of these virtual extension lines 12e.

[0080] In some cases, the protrusion may reach the outer edge of the crown (outer contour line CL4) (see Figure 19(b) below). In this case, there may be only one starting point for the protrusion formed at the boundary between the protrusion and the crown base surface 12b in the crown cross section and / or crown longitudinal section. When there is only one starting point, the arc along the radius of curvature of that starting point may be considered the virtual extension line 12d. That is, in this case, the virtual extension line 12d may be a circle passing through three points: the first point which is the starting point, the second point 0.5 mm away from the first point, and the third point 0.5 mm away from the second point.

[0081] In determining the virtual extension plane 12c, the crown cross section lines may be used preferentially over the crown longitudinal section lines. The virtual extension plane 12c can be determined by a set of virtual extension lines 12d based on the crown cross section lines. If the virtual extension plane 12c is unclear from the set of virtual extension lines 12d, the virtual extension plane 12c may be determined by a set of virtual extension lines 12e based on the crown longitudinal section lines.

[0082] The height H1 of the projection 20 can be defined as the height from the virtual extension surface 12c. As shown in Figure 11, the normal LN of the virtual extension surface 12c at a certain point f1 has an intersection point f2 with the outer surface of the projection 20. The distance from point f1 to intersection point f2 can be defined as the height H1 of the projection 20 at intersection point f2. If the projection does not intersect the normal LN of the virtual extension surface 12c but intersects the normal of the crown base surface 12b at a certain point, the height H1 at that point is defined as the height from the crown base surface 12b. In this case as well, the length of the normal is the height H1.

[0083] Figure 13(a) is a silhouette of the heel projection diagram in Figure 5. Figure 13(b) shows a portion of the contour line of this silhouette. The contour line of this silhouette is the outer contour line CL6 of the heel projection diagram of head 4. Figure 13(b) shows a portion of the outer contour line CL6 of the heel projection diagram of head 4.

[0084] In the heel projection view of head 4, the outer contour line CL6 of the crown outer surface has a protrusion 30. This protrusion 30 is also called the silhouette protrusion. As mentioned above, the projection 20 is visible in the heel projection view (Figure 5). The silhouette protrusion 30 is formed by the projection 20. The silhouette protrusion 30 expands the silhouette area S1 of the heel projection view. That is, the projection 20 expands the silhouette area S1 of the heel projection view. The silhouette area S1 is the area of ​​the figure formed by the outer contour line CL6 of the heel projection view, and is the area of ​​the silhouette shown in Figure 13(a).

[0085] The inflection point on the outer contour line CL6 in the heel projection can be the starting point of the silhouette protrusion. The vertex of the bend on the outer contour line CL6 in the heel projection can be the starting point of the silhouette protrusion. In this embodiment, the vertex, rather than the inflection point, is the starting point of the silhouette protrusion 30 on both sides of the silhouette protrusion 30. As shown in Figure 13(b), in the silhouette protrusion 30 of this embodiment, the vertices P31 and P32 of the bend are the starting points of the silhouette protrusion 30.

[0086] A cubic Bézier curve can also be drawn for this silhouette protrusion 30 using the method described above. This Bézier curve is shown by the dashed line in Figure 13(b). This Bézier curve is a curve that smoothly connects the adjacent curves on both sides of the silhouette protrusion 30. This Bézier curve can become the virtual contour line 30a of the heel projection when the protrusion 20 is absent. The area enclosed by the line of the silhouette protrusion 30 and the virtual contour line 30a is the additional area S2 due to the protrusion 20. In this embodiment, the additional area S2 is the area of ​​the part indicated by hatching in Figure 13(b). The additional area S2 is the increment due to the protrusion 20 from the silhouette area S1.

[0087] In the heel projection view, the protrusion constitutes the outer contour line CL6 of the head, but there are cases where a silhouette protrusion is not formed. For example, if the protrusion reaches the outer peripheral edge (outer contour line CL4) of the crown and extends along this outer peripheral edge, a silhouette protrusion may not be formed. However, even in such cases, the protrusion is visible in the heel projection view, and the protrusion increases the silhouette area S1. In other words, even in this case, there is an additional area S2 caused by the protrusion. For example, the silhouette area S11 of a head from which the protrusion has been removed by replacing it with a virtual extension surface 12c and the silhouette area S12 of a head with the protrusion can be considered. The area (S12-S11) can be the additional area S2.

[0088] From the viewpoint of suppressing and stabilizing toe-down, the additional area S2 is 30 mm 2 The above is preferable, 50 mm 2 The above is more preferable, 100 mm 2 The above is more preferable. From the viewpoint of reducing air resistance in position 6, there are limits to the height and volume of the protrusion. From this viewpoint, the added area S2 is 500 mm 2 The following is preferable: 400mm 2 The following is more preferable: 300mm 2 The following are preferable.

[0089] From the viewpoint of suppressing and stabilizing toe-down, the ratio (S2 / S1) is preferably 0.005 or higher, more preferably 0.008 or higher, and even more preferably 0.015 or higher. From the viewpoint of reducing air resistance in position 6, there are limits to the height and volume of the protrusion. From this viewpoint, the ratio (S2 / S1) is preferably 0.10 or less, more preferably 0.08 or less, and even more preferably 0.06 or less. S2 / S1 is the ratio of the added area S2 to the silhouette area S1.

[0090] Referring to Figure 6, the plane on which the intersection line PL with the outer crown surface 12a forms a closed figure is called the crown cutting plane. In Figure 6, this crown cutting plane CP1 is shown by a dashed line. Although not shown in the side view of Figure 6, in the plan view, the intersection line PL between the outer crown surface 12a and the crown cutting plane CP1 forms a closed figure on the crown cutting plane CP1. The intersection line PL is an endless ring line. Since Figure 6 is a side view, the intersection line PL is shown as a point.

[0091] The crown excision plane CP1 cuts off the outer surface 12a of the crown. The solid formed by the cut-off crown excision plane CP1 is called the excision solid. The volume of this excision solid is called the excision volume. The length of the intersection line PL is L (mm), and the excision volume is V (mm). 3 ) is defined as follows. Length L is the length of the intersection line PL itself. In other words, length L is the distance of the intersection line PL. For example, if the projection is a cone, the crown cutting plane CP1 cuts this cone, and the intersection line PL is a circle, then length L is the circumference of this circle. In the embodiment of Figure 3, this intersection line PL can be an endless ring line of a roughly quadrilateral. In this case, length L is the distance of the intersection line PL of this roughly quadrilateral.

[0092] The ratio (V / L) can serve as an indicator of the degree of protrusion of the crown outer surface 12a. A larger ratio (V / L) indicates a greater degree of protrusion. It is preferable that the crown outer surface 12a has a portion where the ratio (V / L) is greater than the threshold X. In other words, it is preferable that the crown excision plane CP1 be set on the crown outer surface 12a such that the ratio (V / L) is greater than the threshold X.

[0093] The portion where the ratio (V / L) is greater than the threshold X may be at least a part of the protrusion 20. Preferably, all of the intersection lines PL when the ratio (V / L) is greater than the threshold X are intersection lines of the protrusion 20 and the crown cutting plane CP1. In other words, it is preferable that the crown cutting plane CP1 of the protrusion 20 can be set such that the ratio (V / L) is greater than the threshold X. The crown cutting plane CP1 shown in Figure 6 is also set at a position where all of the intersection lines PL are intersection lines of the protrusion 20 and the crown cutting plane CP1. When all of the intersection lines PL are intersection lines of the protrusion 20 and the crown cutting plane CP1, the maximum value of the cutting volume V is preferably 50% or more, more preferably 60% or more, and more preferably 70% or more of the volume of the protrusion 20. Note that the volume of the protrusion 20 may be the volume of the portion cut off by the virtual extension plane 12c. When all of the intersection lines PL become the intersection lines of the protruding portion 20 and the crown cutting plane CP1, the crown cutting plane CP1 may intersect with the virtual extension plane 12c.

[0094] From the viewpoint of increasing the degree of protrusion of the protruding portion 20 and thereby increasing the additional area S2 of the heel projection, the threshold X is preferably 20 or more, more preferably 30 or more, and even more preferably 40 or more. Excessive protrusion can cause an unnatural appearance. From this viewpoint, the threshold X is preferably 500 or less, more preferably 450 or less, and even more preferably 400 or less.

[0095] Figure 14 is a plan view of the head 40 of the second embodiment. The only difference between this head 40 and the head 4 described above is the shape of the protruding portion.

[0096] The head 40 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The striking face 10a has a face center Fc as defined above. The crown portion 12 has a projection 50 on the crown outer surface 12a. The projection 50 is hollow. The projection 50 forms a convex shape on the crown outer surface 12a and a concave shape on the inner surface of the crown.

[0097] Similar to head 4, the protrusion 50 is not visible in the front view of head 40 as seen from the face side. The entire protrusion 50 is located on the outer surface 12a of the crown. Head 40 has an outer contour line CL2 in its plan view (plan view). The protrusion 50 does not reach the outer contour line CL2. The protrusion 50 does not extend beyond the outer surface 12a of the crown. The entire protrusion 50 is located on the heel side of the face center.

[0098] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protruding portion 50 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface. This convex curved surface is convex toward the outside of the head 40.

[0099] The projection 50 has a contour line CL50, an upper surface 52, and a side wall surface 54. The contour line CL50 is the boundary line between the crown base surface 12b and the projection 50. In the plan view of the head 40, the projection 50 is approximately rectangular (approximately trapezoidal). The contour line CL50 forms an approximately rectangular shape. The contour line CL50 has a first side CL51, a second side CL52, a third side CL53, and a fourth side CL54.

[0100] The first side CL51 forms the face-side side of the protruding portion 50. The first side CL51 extends towards the back as it moves towards the toe. The first side CL51 connects the second side CL52 and the fourth side CL54.

[0101] The second side CL52 constitutes the heel-side side of the protruding portion 50. The second side CL52 extends towards the back as it moves towards the toe. The second side CL52 connects the first side CL51 and the third side CL53. The second side CL52 is a curved shape that convex outwards from the head 40.

[0102] The third side CL53 constitutes the back side of the protruding portion 50. The third side CL53 extends towards the back as it approaches the toe side. The third side CL53 connects the second side CL52 and the fourth side CL54.

[0103] The fourth side CL54 constitutes the toe-side side of the protruding portion 50. The fourth side CL54 extends towards the back as it approaches the toe. The fourth side CL54 connects the third side CL53 and the first side CL51.

[0104] The first side CL51, the second side CL52, and the third side CL53 each serve as the base points of the side wall surface 54. That is, the first side CL51, the second side CL52, and the third side CL53 each constitute the boundary line between the side wall surface 54 and the crown base surface 12b. On the other hand, the fourth side CL54 does not serve as the base point of the side wall surface 54. The fourth side CL54 constitutes the boundary line between the crown base surface 12b and the top surface 52.

[0105] Figure 15 is a plan view of the head 60 of the third embodiment. The only difference between this head 60 and the head 4 described above is the shape of the protruding portion.

[0106] The head 60 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The striking face 10a has a face center Fc as defined above. The crown portion 12 has a projection 70 on the crown outer surface 12a. The projection 70 is hollow. The projection 70 forms a convex shape on the crown outer surface 12a and a concave shape on the inner surface of the crown.

[0107] Similar to head 4, the protrusion 70 is not visible in the front view of head 60 as seen from the face side. The entire protrusion 70 is located on the outer surface 12a of the crown. Head 60 has an outer contour line CL2 in its plan view (plan view). The protrusion 70 does not reach the outer contour line CL2. The entire protrusion 70 is located on the heel side of the face center.

[0108] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protruding portion 70 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0109] The projection 70 has a contour line CL70, an upper surface 72, and side wall surfaces 74. The contour line CL70 is the boundary line between the crown base surface 12b and the projection 70. In the plan view (plan view) of the head 60, the projection 70 is approximately pentagonal. The contour line CL70 forms the approximately pentagon. All sides constituting this approximately pentagon have side wall surfaces 74. Although not visible at the angle in Figure 15, the side closest to the outer contour line CL2 also has a side wall surface 74.

[0110] Figure 16 is a plan view of the head 80 of the fourth embodiment. The only difference between this head 80 and the head 4 described above is the shape of the protruding portion.

[0111] The head 80 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The striking face 10a has a face center Fc as defined above. The crown portion 12 has a projection 90 on the crown outer surface 12a. The projection 90 is hollow. The projection 90 forms a convex shape on the crown outer surface 12a and a concave shape on the inner surface of the crown.

[0112] Similar to head 4, the protrusion 90 is not visible in the front view of head 80 from the face side. The entire protrusion 90 is located on the outer surface 12a of the crown. Head 80 has an outer contour line CL2 in its plan view. The protrusion 90 does not reach the outer contour line CL2. The entire protrusion 90 is located on the heel side of the face center.

[0113] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protruding portion 90 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0114] The projection 90 has a contour line CL90, an upper surface 92, and side wall surfaces 94. The contour line CL90 is the boundary line between the crown base surface 12b and the projection 90. In the plan view of the head 80, the projection 90 is approximately rectangular. The contour line CL90 forms an approximately rectangular shape. All sides constituting this approximately rectangular shape have side wall surfaces 94. Although not visible at the angle in Figure 16, the side closest to the outer contour line CL2 also has a side wall surface 94.

[0115] Figure 17 is a plan view (plan view) of the head 100 of the fifth embodiment. The only difference between this head 100 and the head 4 described above is the shape of the protruding part.

[0116] The head 100 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The striking face 10a has a face center Fc as defined above. The crown portion 12 has a projection 110 on the crown outer surface 12a. The projection 110 is hollow. The projection 110 forms a convex shape on the crown outer surface 12a and a concave shape on the inner surface of the crown.

[0117] Similar to head 4, the protrusion 110 is not visible in the front view of head 100 as seen from the face side. The entire protrusion 110 is located on the outer surface 12a of the crown. Head 100 has an outer contour line CL2 in its plan view (plan view). The protrusion 110 does not reach the outer contour line CL2. The entire protrusion 110 is located on the heel side of the face center.

[0118] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protrusion 110 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0119] The projection 110 has a contour line CL110, a ridge line 112 formed by the vertices, and side wall surfaces 114. The ridge line 112 is formed by the intersection of the side wall surfaces 114. The projection 110 does not have an upper surface. The contour line CL110 is the boundary line between the crown base surface 12b and the projection 110. The projection 110 is formed by one ridge line 112 and two side wall surfaces 114. The projection 110 constitutes a convex ridge.

[0120] Figure 18 is a plan view of the head 120 of the sixth embodiment. The only difference between this head 120 and the head 4 described above is the shape of the protruding portion.

[0121] The head 120 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The striking face 10a has a face center Fc as defined above. The crown portion 12 has a projection 130 on the crown outer surface 12a. The projection 130 is hollow. The projection 130 forms a convex shape on the crown outer surface 12a and a concave shape on the inner surface of the crown.

[0122] Similar to head 4, the protrusion 130 is not visible in the front view of head 120 as seen from the face side. The entire protrusion 130 is located on the outer surface 12a of the crown. Head 120 has an outer contour line CL2 in its plan view (plan view). The protrusion 130 does not reach the outer contour line CL2. The entire protrusion 130 is located on the heel side of the face center.

[0123] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protruding portion 130 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0124] The protruding portion 130 is divided into multiple (two) parts. The protruding portion 130 has a first part 132 and a second part 134. The first part 132 and the second part 134 are separate from each other. A dividing groove 136 is formed between the first part 132 and the second part 134. This dividing groove 136 extends in a curved manner.

[0125] Figure 19(a) shows a portion of the outer contour line of the head 140 of the seventh embodiment, viewed from the toe-side and back-side direction. The head 140 has a projection 150. The projection 150 is the same as the projection 20 of the first embodiment, except that the side wall surface 24 along the third side CL23 of the contour line CL20 is recessed. In the head 140, a space SP is formed between the highest part 152 of the projection 150 and the crown outer surface 12a. The highest part 152 is the part with the maximum height H1. The definition of height H1 is as described above. From the viewpoint of increasing the drag force at position 9, it is preferable that the space SP be provided on the contour-adjacent wall surface CW (described later).

[0126] Figure 19(b) shows a portion of the outer contour of the head 154 of the eighth embodiment, viewed from the toe-side and back-side direction. The head 154 has a projection 156. The projection 156 reaches the outer edge (outer contour line CL4) of the crown. In a plan view of the head 154, a portion of the contour line of the projection 156 coincides with the outer contour line CL4 of the crown.

[0127] Figure 20(a) is a perspective view of the head 160 of the ninth embodiment, and Figure 20(b) is a cross-sectional view along line bb in Figure 20(a). Figure 21(a) is a perspective view of the head body 160h of the head 160, and Figure 21(b) is a cross-sectional view along line bb in Figure 21(a). In Figures 20(b) and 21(b), the cross-section of the head body is omitted, and only the cross-sectional lines of the outer surface of the head body are shown.

[0128] The head 160 comprises a head body 160h, a protruding portion 170, and a fixing jig 172. The protruding portion 170 is detachably attached to the head body 160h. The protruding portion 170 is composed of a protruding member 174, which is a separate component from the head body. The protruding member 174 is detachably fixed to the head body 160h by the fixing jig 172.

[0129] The head body 160h has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The striking face 10a has a face center Fc as defined above. The crown portion 12 has a projection 170 on the crown outer surface 12a. The projection 170 is composed of a projection member 174. The projection member 174 is detachably fixed to the crown outer surface 12a.

[0130] Similar to head 4, the protrusion 170 is not visible in the front view of head 160 as seen from the face side. The entire protrusion 170 is provided on the outer surface 12a of the crown. Head 160 has an outer contour line CL2 in its plan view (plan view).

[0131] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protruding portion 170 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0132] The head body 160h has a port 162. In this embodiment, the port 162 constitutes a screw hole that forms a female screw. In this embodiment, the fixing jig 172 is a male screw. The fixing jig 172 can be screw-connected to the port 162. Note that in Figure 20(b), the details of the protrusions and recesses of the screw portion in the port 162 and the fixing jig 172 are omitted.

[0133] The protruding member 174 has a base portion 174a and a vertical wall portion 174b rising from the base portion 174a. The vertical wall portion 174b is formed on the edge of the base portion 174a. In plan view, the protruding member 174 is approximately polygonal (approximately quadrilateral). In plan view, the protruding member 174 has multiple (four) sides. Of these, the vertical wall portion 174b is provided on one side. The base portion 174a has a through hole 174c through which the fixing jig 172 is inserted.

[0134] Thus, in this embodiment, the protruding member 174 is secured by screws using a fixing jig 172. However, the fixing structure of the protruding member 174 is not limited to screw fastening.

[0135] This structure, having vertical wall portions 174b, can increase the added area S2 while suppressing air resistance at position 6. The vertical wall portions 174b are provided only on the contour-adjacent side CS (described later). The vertical wall portions 174b constitute the contour-adjacent wall surface CW (described later). The vertical wall portions 174b effectively increase the added area S2.

[0136] Figure 22(a) is a perspective view of the head 180 of the tenth embodiment, Figure 22(b) is a cross-sectional view along line bb in Figure 22(a), and Figure 22(c) is a cross-sectional view along line cc in Figure 22(a). Figure 23(a) is a perspective view of the head body 180h of the head 180, Figure 23(b) is a cross-sectional view along line bb in Figure 23(a), and Figure 23(c) is a cross-sectional view along line cc in Figure 23(a). In Figures 22(b), 22(c), 23(b), and 23(c), the cross-section of the head body is omitted, and only the cross-sectional lines of the outer surface of the head body are shown.

[0137] The head 180 comprises a head body 180h, a protrusion 190, and a fixing jig 192. The fixing jig 192 comprises a screw member 194 and a screw hole member 196. The protrusion 190 is detachably attached to the head body 180h. The protrusion 190 is composed of a protrusion member 198, which is a separate component from the head body 180h. The protrusion member 198 is detachably fixed to the head body 180h by the fixing jig 192.

[0138] The head body 180h has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking face 10a. The striking face 10a is the outer surface of the face portion 10. The crown portion 12 forms the crown outer surface 12a. The sole portion 14 forms the sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The crown portion 12 has a projection 190 on the crown outer surface 12a. The projection 190 is composed of a projection member 198. The projection member 198 is detachably fixed to the crown outer surface 12a.

[0139] Similar to head 4, in head 180, the protrusion 190 is not visible in the front view of the head as seen from the face side. The entire protrusion 190 is located on the outer surface 12a of the crown.

[0140] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protrusion 190 is composed of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0141] The head body 180h has a port 182. In this embodiment, the port 182 is a recess. A screw hole member 196 is fixed to this port 182. This fixing can be done, for example, by adhesive, welding, etc. The screw hole member 196 has a screw hole 196a. A screw member 194 is screw-connected to the screw hole 196a. Note that in Figures 22(b), 22(c), 23(b), and 23(c), the depiction of the irregularities of the screw portion in the screw member 194 and the screw hole 196a is omitted.

[0142] The protruding member 198 has a base portion 198a and a vertical wall portion 198b rising from the base portion 198a. The vertical wall portion 198b is formed on the edge of the base portion 198a. In plan view, the protruding member 198 is approximately polygonal (approximately quadrilateral). In plan view, the protruding member 198 has multiple (four) sides. Of these, the vertical wall portion 198b is provided on one side. The base portion 198a has a through hole 198c through which the screw member 194 is inserted.

[0143] Thus, in this embodiment as well, the protruding member 198 is screwed in by the fixing jig 192. In this embodiment, the screw hole is formed by the screw hole member 196. This embodiment differs from the ninth embodiment in that it is not necessary to provide a screw hole in the head body 180h.

[0144] The screw hole member 196 may be detachably attached to the head body 180h. For example, the screw hole member 196 may be attached to the head body 180h by screw connection. In this case, the screw hole member 196 can be replaced. By replacing it, the weight of the screw hole member 196 can be adjusted. For example, the screw hole member 196 can be made relatively lighter when the protruding member 198 is attached, and relatively heavier when the protruding member 198 is not attached. In this case, the difference in head weight between when the protruding member 198 is attached and when it is not can be reduced. In addition, it is possible to make the head weight the same when the protruding member 198 is attached and when it is not.

[0145] Figure 24 shows the movement of golf club 2 during the downswing. The swing begins with the backswing, progresses through the top of the swing, and then transitions to the downswing, culminating in impact. As the downswing progresses, the club head speed accelerates. Also, as the downswing progresses, the club head's position changes.

[0146] At a specific point during the downswing, the shaft 6 of golf club 2 is parallel to the ground. This position of golf club 2 is also called position 9. The position of the club at impact is also called position 6. The position midway between position 9 and position 6 is sometimes called position 7.5. These terms liken the golf club 2 during the swing to the hands of a clock. For example, position 9 is derived from the 9 o'clock position on an analog clock.

[0147] The club head's position during the downswing is as follows: During the downswing, a wrist turn occurs, and the clubface closes by the time of impact. Therefore, at impact, the club head moves with its face leading. That is, at impact, the club head moves towards the face in the face-back direction. Before the wrist turn occurs, the club head moves with its heel leading. Traditionally, it was believed that before the wrist turn occurred, the club head was moving towards the heel in the toe-heel direction.

[0148] However, the inventors have found that the direction of the club head's movement at position 9 is substantially the heel side of the inclined toe-heel direction, rather than the heel side of the toe-heel direction. In other words, they found that at position 9, the club head moves with the heel projection (Figure 5) as the front. Due to the centrifugal force acting on the club head from the top of the swing to position 9, toe-down occurs at position 9. Also, at position 9, the wrist cock is released. When the wrist cock is released, the club rotates around the grip, and the position of the club head changes in the same way as toe-down. As a result of these factors, it was found that the direction of the club head's movement at position 9 is substantially the inclined toe-heel direction.

[0149] By providing a protrusion 20 on the crown portion 12 and increasing the silhouette area of ​​the heel projection diagram, the drag force (air resistance force) acting on the head 4 at position 9 increases. This drag force counteracts a portion of the centrifugal force acting on the head's center of gravity CG. Therefore, this increase in drag force reduces the force causing toe-down, and toe-down is suppressed.

[0150] Furthermore, the protrusion 20 provided on the crown section 12 can generate lift. In position 9, air flows in the inclined toe-heel direction. This air generates lift on the head 4 in the same way as the lift acting on an airplane wing. By providing the protrusion 20, the lift in position 9 is increased.

[0151] The protrusion 20 is not visible in the front view from the face side. The protrusion 20 does not constitute the outer contour line of the head in the front view of the head as seen from the face side. Therefore, the protrusion 20 has virtually no effect on the drag (air resistance force) at position 6. In effect, the head speed is not reduced by the protrusion 20.

[0152] Figures 25(a) and 25(b) are conceptual diagrams illustrating the forces acting on the head 200 at position 9. Figure 25(c) shows the head 200 at impact. The head 200 does not have any protrusions on the crown. Figures 26(a) and 26(b) are conceptual diagrams illustrating the forces acting on the head 4 at position 9. Figure 26(c) shows the head 4 at impact. The head 4 is the first embodiment described above.

[0153] A centrifugal force acts on the head 200 in position 9. This centrifugal force acts along the straight line connecting the center of rotation of the golf club 2 and the center of gravity CG of the head. This centrifugal force is decomposed into a component F1 parallel to the shaft axis Z and a component F2 perpendicular to the shaft axis Z. On the other hand, a drag force (air resistance force) and a lift force act on the head 200 in position 9. The drag force and lift force act in a direction that counteracts the centrifugal force. The resultant force of the drag force and lift force is decomposed into a component F3 parallel to the shaft axis Z and a component F4 perpendicular to the shaft axis Z. These forces F1 to F4 are conceptually shown by arrows. The centrifugal force is greater than the drag force and lift force, resulting in toe-down. As a result, as shown in Figure 25(c), the toe side of the head 200 drops down, the back side of the head 200 drops down, and the striking face 10a opens.

[0154] By providing the protrusion 20, the drag and lift at position 9 are increased. The protrusion 20 increases the additional area S2 in the heel projection diagram, increasing the drag. In addition, the protrusion 20 increases the airflow velocity above the head 4 at position 9, increasing the lift. Due to the increase in drag and lift, forces F3 and F4 increase (see the black arrows in Figures 26(a) and 26(b)). As a result, the force that counteracts the centrifugal force becomes larger, and toe-down is suppressed. That is, the downward movement of the toe and back of the head 4 is suppressed, and the opening of the striking face 10a is suppressed (see Figure 26(c)).

[0155] Note that the size and relative magnitudes of the force arrows in Figures 25(a), (b) and 26(a), (b) are not accurate. Similarly, the head posture and its relationships in Figures 25(c) and 26(c) are not accurate. These drawings are intended to provide a qualitative understanding of the effects of this embodiment.

[0156] Except for the embodiment shown in Figure 17, in each of the embodiments described above, the protrusion has an upper surface and a side wall surface extending from the upper surface to the outer edge of the protrusion. By providing the side wall surface, the height H1 of the protrusion can be increased, making it possible to effectively increase the added area S2.

[0157] In the head 4 of the first embodiment, the height H1 of the upper surface 22 decreases as it approaches the center of the head. The center of the head on the center side may refer to the centroid CR in the plan view of the head 4 (see Figure 3). In the head in the above reference state, multiple planes can be set that are perpendicular to the ground plane HP, intersect the upper surface 22, and pass through the centroid CR. In the cross section formed by these planes, the height H1 of the upper surface 22 decreases as it approaches the center of the head (towards the centroid CR). In this configuration, the volume of the protruding portion 20 can be reduced while increasing the added area S2. In addition, in the airflow at position 9, turbulence of the airflow is suppressed, and air flows more easily along the outer surface 12a of the crown. This airflow contributes to an increase in lift.

[0158] In the head 4 of the first embodiment, the height H1 of the upper surface 22 decreases towards the face. That is, in the cross section along the face-back direction (the crown vertical cross section line described above), the height H1 of the upper surface 22 decreases towards the face. As a result, a protruding portion 20 with a large added area S2 that is not visible from the face side can be easily constructed. In addition, the influence on the airflow at impact (flow in the face-back direction) is reduced, and the influence on head speed can also be reduced.

[0159] In the head 80 of the fourth embodiment, the height H1 of the upper surface 92 decreases towards the back. That is, in the cross section along the face-back direction (the crown vertical cross section line described above), the height H1 of the upper surface 92 decreases towards the back. As a result, the generation of turbulence in the airflow at impact (flow in the face-back direction) is suppressed, and the decrease in head speed is suppressed.

[0160] In the head 140 of the seventh embodiment, a space SP is formed between the highest point 152 of the protrusion 150 and the outer surface 12a of the crown. This configuration with space SP facilitates the capture of airflow. This configuration contributes to an increase in drag at position 9.

[0161] In the head 100 of the fifth embodiment, the protruding portion 110 has a ridge line 112 formed by vertices and a side wall surface 114 extending from the ridge line 112 to the outer edge CL110 of the protruding portion 110. With this configuration, it is possible to reduce the volume of the protruding portion 110 while increasing the additional area S2. In this protruding portion 110, it is possible to reduce the influence on the air flow at impact (position 6) while increasing the drag force at position 9.

[0162] In the head 160 of the ninth embodiment, the head 160 has a head main body 160h constituting the crown portion 12 and a protruding member 174 that is detachably fixed to the head main body 160h and constitutes the protruding portion 170. With this configuration, the protruding portion 170 can be manufactured from a material different from that of the head main body 160h (such as resin), and the protruding portion 170 can be lightened or the degree of freedom in molding the protruding portion 170 can be increased. Also, the performance of the head can be changed by attaching and detaching the protruding member 174. The protruding member 174 is detachably fixed to the head main body 160h by a fixing jig 172. Therefore, it is possible to facilitate the attachment and detachment of the protruding member 174. Also, a configuration for attaching and detaching the protruding member 174 using a dedicated tool can be achieved, and it becomes easy to conform to the rules.

[0163] By increasing the height H1, the additional area S2 can be increased. From this perspective, the maximum value of the height H1 of the protruding portion is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. From the perspective of the design freedom of the head center of gravity position, the maximum value of the height H1 of the protruding portion is preferably 20 mm or less, more preferably 17 mm or less, and even more preferably 15 mm or less.

[0164] The area of the crown outer surface 12a on the heel side relative to the face center Fc is Sh (mm 2 ) and is so defined. Also, the area of the protruding portion is St (mm 2) is defined as follows. Area Sh and Area St are measured in a plan view of the head (Figure 3, etc.). In Figure 3, Area Sh is the area of ​​the part on the heel side of the straight line Lc that passes through the face center Fc and extends in the face-back direction. From the viewpoint of increasing drag and lift at position 9, the proportion of Area St to Area Sh is preferably 5% or more, more preferably 15% or more, and more preferably 20% or more. From the viewpoint of design freedom of the head center of gravity position, the proportion of Area St to Area Sh is preferably 70% or less, more preferably 60% or less, and more preferably 50% or less.

[0165] As explained in Figure 3, the protruding portion 20 has a contour line CL20. A distance D1 is defined between each point on the contour line CL20 and the outer contour line CL2. As shown in Figure 7, this distance D1 is defined as the distance (straight-line distance) along the cross-sectional line.

[0166] Each side constituting the contour line CL20 includes the side closest to the outer contour line CL2. In the embodiment of Figure 3, the side closest to the outer contour line CL2 is the third side CL23. This side is the contour proximity side CS that is closest to the outer contour line CL2 among the multiple sides. In the embodiment of Figure 14, the second side CL52 is the contour proximity side CS. The minimum value of distance D1 at the contour proximity side CS is smaller than the minimum value of distance D1 at the other sides. The maximum value of distance D1 at the contour proximity side CS is smaller than the maximum value of distance D1 at the other sides. The maximum value of distance D1 at the contour proximity side CS is smaller than the minimum value of distance D1 at the other sides.

[0167] As shown in Figure 3, the adjacent contour edge CS follows the outer contour line CL2. The outer contour line CL2 includes the outer contour line CL4 of the crown portion 12 in the plan view of the head. The adjacent contour edge CS follows the outer contour line CL4.

[0168] By providing a contour-proximity edge CS, the protrusion 20 approaches the outer contour line CL4 on the heel side. This effectively increases the additional area S2 in the heel projection view. From this viewpoint, the maximum value of the distance D1 in the entire contour-proximity edge CS is preferably 25 mm or less, more preferably 20 mm or less, and even more preferably 15 mm or less. This maximum value may also be 0 mm. When the protrusion 20 reaches the outer contour line CL4 of the crown portion 12, the maximum value of the distance D1 is 0 mm.

[0169] The contour-proximity side CS is preferably aligned with the outer contour line CL4. In this case, the added area S2 can be effectively increased. From this viewpoint, the maximum value D1max and minimum value D1min of D1 in the contour-proximity side CS are considered. When the contour-proximity side CS is aligned with the outer contour line CL4, the difference (D1max-D1min) becomes smaller. From this viewpoint, the difference (D1max-D1min) is preferably 15mm or less, more preferably 13mm or less, and more preferably 10mm or less. It is even more preferable that the difference (D1max-D1min) is 0mm.

[0170] From the viewpoint of efficiently increasing the added area S2, the length of the contour-proximal side CS is preferably 20 mm or more, more preferably 30 mm or more, and even more preferably 40 mm or more. From the viewpoint of suppressing excessive extension toward the face and reducing air resistance at position 6, the length of the contour-proximal side CS is preferably 90 mm or less, more preferably 80 mm or less, and even more preferably 70 mm or less. This contour-proximal side CS is the actual length (path length) of the (three-dimensional) contour-proximal side CS.

[0171] The contour adjacent edge CS preferably has a side wall surface. That is, the protruding portion preferably has a side wall surface with the contour adjacent edge CS as its lower edge. In the embodiment shown in Figure 3, the contour adjacent edge CS has a side wall surface 24. The side wall surface 24 with the contour adjacent edge CS as its lower edge is also referred to as the contour adjacent wall surface. The contour adjacent wall surface CW can efficiently increase the additional area S2 of the heel projection.

[0172] By increasing the height of the contour-adjacent wall surface CW, the additional area S2 can be efficiently increased. From this viewpoint, the height H1 of the upper edge of the contour-adjacent wall surface CW is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. From the viewpoint of design freedom for the center of gravity position of the head, the height H1 of the upper edge of the contour-adjacent wall surface CW is preferably 20 mm or less, more preferably 18 mm or less, and even more preferably 15 mm or less.

[0173] From the viewpoint of increasing the additional area S2 in the heel projection while reducing air resistance at position 6, the upper edge of the contour-adjacent wall surface CW may include the point where the height H1 is maximum at the protruding portion 20.

[0174] In the plan view of Figure 3, the first side CL21 of the contour line CL20 of the protruding portion 20 is the side opposite the contour adjacent side CS. The length of this opposite side PS is preferably shorter than the length of the contour adjacent side CS. By shortening the opposite side PS, the added area S2 can be increased while reducing the influence on the airflow at position 6. The length of this opposite side PS is the actual length (path length) of the (three-dimensional) opposite side PS. The length of the opposite side PS is preferably 90% or less of the length of the contour adjacent side CS, more preferably 80% or less, and even more preferably 70% or less. The length of the opposite side PS may also be 0% of the length of the contour adjacent side CS.

[0175] By lowering the opposing side PS, air resistance at position 6 can be reduced. From this viewpoint, it is preferable that the opposing side PS does not have a side wall surface.

[0176] In the plan view of head 4 (Figure 3), the projection 20 has a tapered shape in which the width W1 decreases as it approaches the opposing side PS from the contour-adjacent wall surface CW. This tapered shape contributes to increasing the added area S2 while reducing the influence on the airflow at position 6. The width W1 can be measured along the direction of the straight line connecting the two ends of the opposing side PS. [Examples]

[0177] The effects of this disclosure will be demonstrated below by the examples provided, but this disclosure should not be interpreted restrictively based on the description of these examples.

[0178] [Test 1: Actual Hitting Evaluation] Multiple testers actually hit the ball with club A, which has no protrusions, and club B, which has protrusions, to confirm the effect of the protrusions.

[0179] The testers were nine golfers with a driver head speed of 34-39 m / s. A XXIO Eleven driver (shaft flex R, loft angle 10.5°) was used as Club A, which had no protrusions. Club B, which had protrusions, was a club with protrusions molded from a sponge mockup attached to the crown of the head of Club A. The sponge mockup was made of sponge material (EVA foam) and was lightweight. Furthermore, adjustments were made so that the head weights of Club A and Club B were the same. The position and shape of the protrusions were the same as those of head 4 in the first embodiment described above.

[0180] Nine testers hit eight balls with each club. For each hit, head speed, impact point, face angle at impact, and ball speed were measured. From this data, the average head speed, head speed variability (standard deviation σ), average distance between impact point and face center, variability between impact point and face center (standard deviation σ), average face angle, variability of face angle (standard deviation σ), and average smash factor were calculated for each tester and each club.

[0181] Figure 27(a) shows the average head speed (H / S) for testers 1 through 9. The left side of the bar graph shows the results for club A (without protrusion), and the right side shows the results for club B (with protrusion). Each arrow indicates whether the head speed increased or decreased due to the presence or absence of the protrusion. The head speed was the same with and without the protrusion. It was confirmed that the head speed did not decrease even with the addition of the protrusion.

[0182] Figure 27(b) shows the average distance between the point of impact and the face center for testers 1 through 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether this distance increased or decreased due to the presence or absence of the protrusion. Of the nine testers, eight experienced a decrease in this distance. It was confirmed that the presence of the protrusion optimized (suppressed) toe-down, bringing the point of impact closer to the face center.

[0183] Figure 28(a) shows the average face angle for testers 1 through 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the face angle increased or decreased due to the presence or absence of the protrusion. A face angle of 0° is most desirable. Of the nine testers, five had a face angle close to 0°, and of these, three had a face angle of almost 0° with club B. It was confirmed that the presence of the protrusion optimizes (suppresses) toe-down and brings the face orientation closer to square.

[0184] Figure 28(b) shows the average smash factor for testers 1 through 9. The smash factor is calculated by dividing the ball speed (B / S) by the club head speed (H / S). The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the smash factor increased or decreased due to the presence or absence of the protrusion. Of the nine testers, eight showed an increase in their smash factor. It was confirmed that the presence of the protrusion optimized (suppressed) toe-down, improving the impact point and collision angle, and thus increasing the smash factor.

[0185] Figure 29(a) shows the standard deviation of head speed (H / S) for testers 1 through 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the variation in head speed increased or decreased due to the presence or absence of a protrusion. The variation in head speed was similar with and without the protrusion.

[0186] Figure 29(b) shows the standard deviation of the distance between the impact point and the face center for testers 1 through 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the variation increased or decreased due to the presence or absence of the protrusion. Of the nine testers, six showed a decrease in this variation. It was confirmed that the presence of the protrusion stabilized toe-down and reduced the variation in the impact point.

[0187] Figure 30 shows the standard deviation of face angle for testers 1 through 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the variation increased or decreased due to the presence or absence of the protrusion. Of the nine testers, six showed a decrease in this variation. It was confirmed that the presence of the protrusion stabilized toe-down and reduced the variation in face angle.

[0188] [Test 2: Evaluation using a swing machine] Using the aforementioned Club A and Club B, toe-down was observed during swings using a swing machine. A Computer Controlled Hitting Machine manufactured by Golf Laboratories, Inc. was used as the swing machine, and the head speed at impact was set to 40 m / s for the test. Strain gauges were attached to the shafts to observe the amount of shaft flex at impact. As a result, Club B (with protrusions) showed a 4% (approximately 3 mm) reduction in toe-down flex at impact compared to Club A (without protrusions). In addition, the change in the point of impact was measured using pressure-sensitive paper. With Club B, the point of impact shifted towards the heel and sole compared to Club A. The distance of this shift in the point of impact was approximately 6 mm. Thus, the swing machine test confirmed that toe-down is suppressed by the protrusions.

[0189] [Test 3: Aerodynamic Simulation] The changes in drag and lift acting on the club head were confirmed through simulation. The simulation was performed using "STAR-CCM" software from Siemens Digital Industries Software, employing a polyhedral rear fine mesh. The shape and position of the protrusion were the same as head 4 in the first embodiment, and the maximum value of the protrusion height H1 was set to 3 mm. The club head speed during the downswing was set to 20 m / s at position 9, 30 m / s at position 7.5, and 40 m / s at position 6. As a result, the drag at position 9 increased by 13% in the direction of club head movement at position 9 (i.e., inclined toe-heel direction). On the other hand, the drag at position 6 (impact) decreased by 2% in the direction of club head movement at position 6 (i.e., face-back direction). In addition, the lift at position 9 increased by 28% in the direction perpendicular to the direction of club head movement at position 9 (i.e., inclined toe-heel direction). These increased drag and lift forces counteracted centrifugal force and reduced the force acting perpendicular to the shaft axis. Due to the increased drag and lift, the force acting perpendicular to the shaft axis at position 9 decreased by approximately 1%. Thus, it was confirmed that the protrusion increased drag and lift at position 9, suppressing toe-down.

[0190] As these evaluation results demonstrate, the advantages of this disclosure are clear.

[0191] The following additional information is disclosed regarding the embodiments described above. [Note 1] The face portion that forms the striking face, The crown portion that forms the outer surface of the crown, The sole portion that forms the outer surface of the sole, A hosel section to which the shaft is attached and which identifies the shaft axis, A golf club head having, The crown portion has a protrusion on its outer surface, In a front view of the head as seen from the face side, the protruding portion does not constitute the outer contour line of the head. A golf club head in which the shaft axis is perpendicular to the ground plane and the face angle is 0 degrees, and in a heel projection view taken from the heel side along the ground plane, the protruding portion constitutes the outer contour line of the head. [Note 2] The golf club head according to Appendix 1, wherein the protruding portion has an upper surface and a side wall surface extending from the upper surface to the outer edge of the protruding portion. [Note 3] The golf club head described in Appendix 2, wherein the height of the upper surface decreases as it approaches the center of the head. [Note 4] The golf club head described in Appendix 2, wherein the height of the upper surface of the protruding portion decreases as it approaches the face. [Note 5] The golf club head as described in Appendix 2, wherein the height of the upper surface of the protruding portion decreases as it moves towards the back. [Note 6] The golf club head according to any one of the appendices 1 to 5, wherein a space is formed between the highest part of the protrusion and the outer surface of the crown. [Note 7] The golf club head according to Appendix 1, wherein the protruding portion has a ridge formed by the apex and a side wall surface extending from the ridge to the outer edge of the protruding portion. [Note 8] The golf club head according to any one of the appendices 1 to 7, wherein the head comprises a head body constituting the crown portion and a protruding member detachably fixed to the head body and constituting the protruding portion. [Note 9] The golf club head as described in Appendix 8, wherein the protruding member is detachably fixed to the head body by a fixing jig. [Note 10] In a plan view of the head, when the area of ​​the outer surface of the crown on the heel side of the face center is Sh, and the area of ​​the protrusion is St, A golf club head as described in any one of the appendices 1 to 9, wherein the proportion of area St to area Sh is between 5% and 70%. [Note 11] It comprises a golf club head, grip, and shaft as described in any one of the appendices 1 to 10. A golf club in which the golf club head is attached to the tip of the shaft and the grip is attached to the rear end of the shaft. [Explanation of symbols]

[0192] 2. Golf Clubs 4, 60, 80, 100, 120, 140, 160, 180... head 6... Shaft 10. Face section 10a...Hitting face 12. Crown section 12a... Crown exterior 12b...Crown base 12c...Virtual extension plane 12d...Virtual extension line 12e...Virtual extension line 14. Sole 16. Hosel section 20, 70, 90, 110, 130, 150, 170, 190...Protrusion 22...Top surface 24. Side wall 174, 198... protruding members CL1...Outer contour line of the head in a front view as seen from the face side. CL6...Outer contour line of the heel projection drawing Z... Shaft axis CG... Head center of gravity

Claims

1. The face portion that forms the striking face, The crown portion that forms the outer surface of the crown, The sole portion that forms the outer surface of the sole, A hosel section to which the shaft is attached and which identifies the shaft axis, A golf club head having, The crown portion has a protrusion on its outer surface, In the front view of the golf club head as seen from the face side, the protruding portion does not constitute the outer contour line of the golf club head. A golf club head in which the entire protruding portion is located on the heel side of the face center.

2. The golf club head according to claim 1, wherein the protruding portion has an upper surface and a side wall surface extending from the upper surface to the outer edge of the protruding portion.

3. The golf club head according to claim 2, wherein the height of the upper surface decreases as it approaches the center of the head.

4. The golf club head according to claim 2, wherein the height of the upper surface of the protruding portion decreases as it approaches the face.

5. The golf club head according to claim 2, wherein the height of the upper surface of the protruding portion decreases as it moves towards the back.

6. The golf club head according to any one of claims 1 to 5, wherein a space is formed between the highest part of the protrusion and the outer surface of the crown.

7. The golf club head according to claim 1, wherein the protruding portion has a ridge line formed by the apex and a side wall surface extending from the ridge line to the outer edge of the protruding portion.

8. The golf club head according to any one of claims 1 to 7, wherein the golf club head comprises a head body constituting the crown portion and a protruding member detachably fixed to the head body and constituting the protruding portion.

9. The golf club head according to claim 8, wherein the protruding member is detachably fixed to the head body by a fixing jig.

10. In a plan view of the golf club head, when the area of ​​the outer surface of the crown on the heel side of the face center is Sh, and the area of ​​the protruding portion is St, A golf club head according to any one of claims 1 to 9, wherein the proportion of area St to area Sh is 5% or more and 70% or less.

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