JP2007037921A - Golf club head and golf club - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf club head and a golf club suppressing the maximum value of a restitution coefficient and having an enlarged sweet area. <P>SOLUTION: This golf club head 100 has a metal outer shell structure composed of titanium and includes a face part, a crown part 20, a sole part 30, a heel part 40, a toe part 50, and a back part 60. The minimum curvature radius in the outer face side of a boundary part between the face part and the crown part 20 and the minimum curvature radius in the outer face side of the boundary part between the face part and the sole part 30 are not less than 6mm and not more than 20 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a golf club head and a golf club, and more particularly to a golf club head and a golf club having an outer shell structure.

  Attempts have heretofore been made to improve the resilience characteristics of golf club heads. It is known that the higher the coefficient of restitution of the golf club head, the higher the initial velocity of the ball at the time of hitting and the greater the flight distance. Therefore, by reducing the rigidity of the face portion, deformation of the face portion at the time of hitting the ball is increased to increase rebound. In this case, for example, a high-strength material is used for the face portion and its thickness is reduced.

  In Japanese Patent Laid-Open No. 06-190088 (Patent Document 1), in order to extend the flight distance of the ball by synchronous deformation with the ball, a plurality of slits extending at intervals are provided along the periphery of the face surface. A golf club head is disclosed. Here, the slits are arranged in a plurality of rows and in a staggered manner toward the rear of the head body.

  Japanese Patent Laid-Open No. 01-91876 (Patent Document 2) discloses a golf club head in which an auxiliary sole plate is fitted to a sole plate body. In Patent Document 2, as described above, a large elastic deformation energy region approaches the vicinity of a collision point with a golf ball that is a collision object, and thus the rebound characteristics of the club head are improved.

  Japanese Patent Laid-Open No. 10-263118 (Patent Document 3) discloses a golf club head having an outer shell structure in which the deflection of the face portion or the relative displacement of the face portion with respect to the golf club head at the time of hitting is increased. A golf club head provided with a deformation assisting portion is disclosed.

  In addition, for example, JP-A-2004-305522 (Patent Document 4), JP-A-2001-246027 (Patent Document 5), JP-A-2002-102394 (Patent Document 6), JP-A-2003-24482 (Patent Document 7), Japanese Patent No. 3469758 (Patent Document 8), Japanese Patent Application Laid-Open No. 2001-353241 (Patent Document 9), and the like disclose a golf club head having an outer shell structure.

  In Japanese Patent Publication No. 07-4438 (Patent Document 10), the upper and lower edge corners of the face surface are respectively formed into curved surfaces having a radius of curvature of 10 mm or more, and uneven portions are formed on both curved surfaces. A golf club head is disclosed.

  Japanese Patent Application Laid-Open No. 2002-17912 (Patent Document 11) discloses an example of a method for measuring the coefficient of restitution of a golf club head.

Japanese Patent Application Laid-Open No. 2002-136625 (Patent Document 12) describes the relationship between the sectional moment of inertia of the plate and the radius of curvature.
Japanese Patent Laid-Open No. 06-190088 Japanese Patent Laid-Open No. 01-91876 Japanese Patent Laid-Open No. 10-263118 JP 2004-305522 A JP 2001-246027 A JP 2002-102394 A JP 2003-24482 A Japanese Patent No. 3469758 JP 2001-353241 A Japanese Patent Publication No. 07-4438 JP 2002-17912 A JP 2002-136625 A

  As a result of the R & A (Royal and Ancient Golf Club of St. Andrews) rule revision, golf club heads with a coefficient of restitution exceeding 0.83 will be banned after January 1, 2008. Therefore, it is necessary to suppress the maximum value of the coefficient of restitution that is maximum near the sweet spot. On the other hand, there is a desire to expand as much as possible the sweet area, which is a region having a relatively high coefficient of restitution, while satisfying the revised rule.

  As the inventors of the present application have studied, in a golf club head having an outer shell structure, the coefficient of restitution at the peripheral edge of the face is made relatively large by increasing the radius of curvature on the outer surface side of the boundary portion between the face portion and its periphery. As a result, it was found that the sweet area expanded. In addition, the “face peripheral part” in the specification of the present application means a part located around the face center part in the face part.

  On the other hand, the golf club heads according to Patent Documents 1 and 2 both expect an improvement in the resilience characteristics due to the elastic deformation effect (spring effect), but the boundary between the face portion and the region adjacent to the face portion. It does not reduce the rigidity of the part, and the effect of suppressing the decrease in the coefficient of restitution of the peripheral edge of the face is not always sufficient.

  Also, Patent Documents 3 to 12 do not disclose the idea of improving the coefficient of restitution of the face periphery by adjusting the radius of curvature of the boundary between the face periphery and its periphery as described above. For example, Patent Documents 3 and 4 disclose that the angle formed by the face portion and its surroundings is adjusted. Even if the angle formed by the face portion and its surroundings is the same, the boundary portion thereof is disclosed. The curvature radius may be different, and conversely, even if the curvature radius of the boundary portion between the face portion and its periphery is the same, the angle formed between the face portion and its periphery may be different. Therefore, the premise and the configuration are completely different from the idea of the present invention of adjusting the radius of curvature on the outer surface side of the boundary portion between the face portion and the periphery thereof and the descriptions in Patent Documents 3 and 4.

  Further, Patent Document 10 discloses that in the course of manufacturing a golf club head, the upper and lower end corners of the face surface are processed so that the radius of curvature is 10 mm or more. From the viewpoint of reducing the force, it is assumed that an uneven shape as a swirl flow generating portion is subsequently formed on the curved surface. By forming the concavo-convex shape, the radius of curvature of the boundary portion between the face portion and its periphery is reduced. Thus, the golf club head according to Patent Document 10 does not increase the radius of curvature of the boundary portion between the face portion and the periphery thereof, and therefore is expected to have an effect of suppressing a decrease in the coefficient of restitution at the peripheral portion of the face. Can not.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a golf club head and a golf club in which the maximum value of the coefficient of restitution is suppressed and the sweet area is expanded. There is.

The golf club head according to the present invention is a golf club head having an outer shell structure.
In one aspect, the golf club head includes a face portion, a back portion, and a crown portion adjacent to the face portion, and passes through the face center and crosses along the face-back direction from the face portion toward the back portion. The minimum radius of curvature on the outer surface side of the boundary portion between the face portion and the crown portion is 6 mm or more and 20 mm or less (preferably 8 mm or more and 12 mm or less).

  In another aspect, the golf club head includes a face portion, a back portion, and a sole portion adjacent to the face portion, passes through the face center, and crosses along the face-back direction from the face portion toward the back portion. The minimum curvature radius on the outer surface side of the boundary portion between the face portion and the sole portion is 6 mm or more and 20 mm or less (preferably 8 mm or more and 12 mm or less).

  In yet another aspect, the golf club head includes a face portion, a back portion, a crown portion and a sole portion adjacent to the face portion, passes through the face center, and faces from the face portion toward the back portion. , The minimum radius of curvature on the outer surface side of the boundary part between the face part and the crown part is 6 mm or more and 20 mm or less (preferably 8 mm or more and 12 mm or less), and the boundary part between the face part and the sole part The minimum radius of curvature on the outer surface side is 6 mm or more and 20 mm or less (preferably 8 mm or more and 12 mm or less).

  In the above golf club head, “cross section along the face-back direction” means “vertical direction when extending in the direction from the face portion toward the back portion and addressing the golf club head with a predetermined lie angle” Means a cross section extending to “Face center” means “the intersection of the center line between the toe side end and the heel side end of the face outline and the center line between the crown side end and the sole side end of the face outline”.

  In yet another aspect, the golf club head includes a face portion, a body portion including a portion adjacent to the face portion and a back portion, and in all cross sections orthogonal to the boundary line between the face portion and the body portion, The minimum radius of curvature on the outer surface side of the boundary portion between the face portion and the main body portion is 6 mm or more and 20 mm or less (preferably 8 mm or more and 12 mm or less).

  In any of the above aspects, it is possible to suppress a decrease in the coefficient of restitution at the face periphery while suppressing the maximum value of the coefficient of restitution. As a result, the sweet area can be expanded while satisfying the regulations regarding the upper limit of the coefficient of restitution.

  In the golf club head, preferably, the minimum curvature radius on the inner surface side of the golf club head is larger than the minimum curvature radius on the outer surface side of the golf club head.

  Thereby, the hot water flow when the golf club head is produced by casting is improved. As a result, the golf club head having the minimum radius of curvature described above is stably manufactured. And the effect which expands a sweet area can be acquired stably.

  A golf club according to the present invention includes the above-described golf club head. As a result, a golf club is obtained in which the maximum value of the coefficient of restitution is suppressed and the decrease in the coefficient of restitution at the peripheral edge of the face is suppressed.

  According to the present invention, in the golf club head, it is possible to suppress a decrease in the coefficient of restitution at the peripheral portion of the face while suppressing the maximum value of the coefficient of restitution. As a result, the sweet area can be expanded while satisfying the regulations regarding the upper limit of the coefficient of restitution.

  Embodiments of a golf club head and a golf club according to the present invention will be described below.

  The golf club head according to the present embodiment is a golf club head having an outer shell structure, and includes a face portion, a crown portion, a sole portion, a heel portion, a toe portion, and a back portion. The A golf club is constructed by assembling a golf club shaft and a grip to the club head.

  The face part is located on the front side of the golf club head, and has a face center part and a face peripheral part located around the face center part. The crown portion, the sole portion, the heel portion, and the toe portion are adjacent to the face portion. The back portion is located on the back side of the golf club head and faces the face portion. The crown portion, the sole portion, the heel portion, the toe portion, and the back portion constitute a “main body portion” in the golf club head.

  The golf club head according to the present embodiment is typically a driver golf club head, but may be other wood type heads.

  In the golf club head, the radius of curvature on the outer surface side of the boundary portion between the face portion and the periphery thereof (crown portion, sole portion, heel portion, and toe portion) is set to be relatively large. For example, in a cross section passing through the face center and extending along the face-back direction (hereinafter, sometimes simply referred to as “face-back cross section”), the minimum curvature radius on the outer surface side of the boundary portion between the face portion and the crown portion Alternatively, the minimum radius of curvature on the outer surface side of the boundary portion between the face portion and the sole portion is about 6 mm to 20 mm (preferably about 8 mm to 12 mm). In the “face-back cross section”, both the minimum curvature radius on the outer surface side of the boundary portion between the face portion and the crown portion, and the minimum curvature radius on the outer surface side of the boundary portion between the face portion and the sole portion. May be about 6 mm or more and 20 mm or less (preferably, about 8 mm or more and 12 mm or less).

  The minimum curvature radius on the outer surface side of the boundary portion between the face portion and the crown portion and the minimum curvature radius on the outer surface side of the boundary portion between the face portion and the sole portion in the “face-back cross section” of the conventional golf club head Is generally about 2 mm to 3 mm.

  On the other hand, in the golf club head according to the present embodiment, the radius of curvature on the outer surface side of the boundary portion between the face portion and the crown portion and / or the sole portion in the “face-back cross section” is set to be relatively large. Yes.

  FIG. 5 is a diagram for explaining the relationship between the sectional moment of inertia and the radius of curvature. Table 1 and FIG. 6 show the relationship between the curvature radius calculated using the model shown in FIG.

In the example of FIG. 5, a plate 200 (thickness: t = 1 mm) having a radius of curvature R is supported by a fulcrum 300 provided with a predetermined interval L (= 8 mm). As shown in Table 1 and FIG. 6, as the radius of curvature of the plate 200 decreases, the cross-sectional secondary moment increases. Conversely, as the radius of curvature R increases, the plate 200 has a shape that is closer to a flat surface, and thus the moment of inertia of the cross section decreases. “P” in FIG. 6 indicates the second moment of inertia of the flat plate. That is, as in the golf club head according to the present embodiment, by increasing the radius of curvature on the outer surface side of the boundary portion between the face portion and its periphery, the cross-sectional secondary moment of the portion is reduced, The part is easily deformed. As a result, the coefficient of restitution at the peripheral edge of the face can be improved and the sweet area can be expanded.

  On the other hand, if the minimum radius of curvature is excessively large, the face portion is too small and the ball striking surface becomes extremely small, which may make the golfer feel uncomfortable with the appearance of the club head or make it difficult to hit the ball. In addition, golf rules 4-1 determined by R & A. a. The general rule states that “a club must not be of a shape or structure that is essentially contrary to tradition and custom”, but if the radius of curvature is further increased, there is a concern that it may be considered a violation of the rule. The On the other hand, in the golf club head according to the present embodiment, the minimum curvature radius is adjusted to be about 20 mm or less (preferably about 12 mm or less). Thereby, the above-described effects can be obtained without deteriorating the appearance of the club head.

  In the present specification, “curvature radius on the outer surface side” means, for example, r1, r2, r3, r4 (r1 <r2 <r4 <r3) in FIG. 7, and “curvature radius on the inner surface side” means, for example, , R1, R2, R3, and R4 (R1 <R2 <R4 <R3) in FIG. The “minimum curvature radius” means the smallest one of the curvature radii sequentially measured along the measurement cross section. For example, when a measurement result as shown in FIG. 7 is obtained, the “minimum curvature radius on the outer surface side” is “r1”, and the “minimum curvature radius on the inner surface side” is “R1”. Here, the “minimum curvature radius” can be measured by a commercially available R gauge. Further, for example, a club head is cut along a cross section along the face-back direction, and the cross section along the face-back direction is illustrated by pressing (tracing) the cross section against paper and tracing it into a computer. Therefore, it can be measured accurately. 8 to 14 illustrate the outline of the head in a cross section along the face-back direction of a conventional golf club head. As shown in FIGS. 8 to 14, in the conventional golf club head, the “minimum curvature radius on the outer surface side” is about 2 to 3 mm, and does not exceed 5 mm at most.

  As described above, the cross section in which the minimum radius of curvature on the outer surface side of the boundary portion between the face portion and its periphery is adjusted is not limited to the “face-back cross section”. For example, in all cross sections orthogonal to the boundary line between the face portion and the “main body portion” of the golf club head, the minimum curvature radius on the outer surface side of the boundary portion between the face portion and the “main body portion” is 6 mm or more and 20 mm or less. The degree (preferably about 8 mm or more and 12 mm or less) may be used. In this case as well, the sweet area can be expanded while satisfying the rules regarding the upper limit of the coefficient of restitution as described above.

  The golf club head may be made of a single metal or may be a combination of a plurality of metals. Further, a combination of a metal and a carbon fiber reinforced resin may be used. Further, the inside of the outer shell structure may be a cavity or may be filled with a foam or the like.

  Examples of the metal constituting the golf club head include iron such as soft iron, titanium, special steel, stainless steel, aluminum, magnesium, tungsten, copper, nickel, zirconium, cobalt, manganese, zinc, silicon, tin, chromium, and these. An alloy or the like is used.

  Here, S15C, S20C, S25C, S30C, S35C, etc. can be used as soft iron. Moreover, as titanium and titanium alloy, pure titanium 1 type, 2 types, 3 types, 4 types, Ti-5Al-2.5V which is α-based titanium alloy, Ti-3Al-2 which is α-β-based titanium alloy .5V, Ti-6Al-4V, Ti-4.5Al-3V-2Fe-2Mo, β-based titanium alloys Ti-15V-3Cr-3Sn-3Al, Ti-10V-2Fe-3Al, Ti-13V-11Cr -3Al, Ti-15Mo-5Zr, Ti-15V-6Cr-4Al, Ti-15Mo-5Zr-3Al, Ti-20V-4AL-1Sn, Ti-22V-4AL, Ti-3Al-8V-6Cr-4Mo-3Zr Etc. can be used. Stainless steel materials include SUS630, austenitic SUS301, 303, 304, 304N1, 304N2, 305, 309S, 310S, 316, 317, 321, 347, XM7, martensitic SUS410, 420, 431, 440, Precipitation hardening type SUS630 and ferrite type SUS405, 430, 444, etc. can be used. As the special steel, high strength steel, ultra high strength steel, ausforming steel, maraging steel, spring steel, and the like can be used. Further, pure aluminum, 2017, 2024, 7075, 3003, 5052, 5056, 6151, 6053, 6061, etc. can be used as aluminum, and AZ63A, AZ81A, AZ91A, AZ91C, WE54, EZ33A, etc. can be used as magnesium. It is.

  The golf club head may be formed by integrally molding a face part and a main body part by precision casting, or a face member manufactured by forging and a main body member molded by precision casting are joined by welding. It may be formed. The face member may be manufactured by billet forging or by plate forging. Furthermore, you may make it the structure which fits the crown member which consists of a lightweight different raw material in a main body member.

  According to the present embodiment, since the boundary portion between the face portion and its surroundings is easily deformed at the time of hitting a ball, the reduction in the restitution coefficient at the peripheral portion of the face is suppressed while suppressing the maximum value of the restitution coefficient of the golf club head. be able to. As a result, the sweet area can be expanded while satisfying the regulations regarding the upper limit of the coefficient of restitution.

  In the golf club head, it is preferable that the minimum curvature radius on the inner surface side is larger than the minimum curvature radius on the outer surface side.

  Thereby, the hot water flow when the golf club head is produced by casting is improved. As a result, the golf club head having the minimum radius of curvature described above is stably manufactured. In addition, by doing as described above, stress concentration at the boundary portion between the face portion and its surroundings can be easily relaxed, and the thickness of the boundary portion can be reduced, and the portion can be further easily deformed. become. As a result, the effect of expanding the sweet area is further enhanced.

  In addition, the R & A rule after January 1, 2008 requires that the maximum coefficient of restitution be suppressed, but if this is handled by increasing the face thickness, the mass of the face portion Will increase. In large-sized golf club heads (for example, driver golf club heads) that have become mainstream in recent years (especially driver golf club heads), control of the center of gravity and increase of moment of inertia are important issues. Increasing the number may reduce the degree of freedom of design in consideration of these.

  On the other hand, in the golf club head according to the present embodiment, the substantial area of the face portion is reduced by increasing the radius of curvature of the boundary portion between the face portion and its periphery. As a result, the maximum value of the coefficient of restitution can be reduced without excessively increasing the face thickness. Then, by appropriately arranging the surplus mass, the center of gravity of the head can be brought close to a desired position, or the moment of inertia of the club head can be increased. That is, the degree of freedom in designing the club head is improved.

  In the above, the explanation has mainly been given on expanding the sweet area by increasing the radius of curvature of the boundary portion between the face portion and its surroundings, but further, for example, by changing the material or adjusting the heat treatment method. By doing so, the Young's modulus of the peripheral portion of the face may be kept lower than the Young's modulus of the central portion of the face. Moreover, you may further reduce the thickness of a face peripheral part. Thereby, a face peripheral part becomes easy to deform | transform and a sweet area can be expanded further.

  In the following, one embodiment of a golf club head according to the present invention will be described. Note that the same or corresponding portions are denoted by the same reference numerals, and the description thereof may not be repeated.

  FIG. 1 is a view showing a golf club head according to the present embodiment. FIG. 2 is a view of the golf club head shown in FIG. 1 as viewed from the direction of arrow II. Referring to FIGS. 1 and 2, a golf club head 100 is a golf club head having a metal outer shell structure made of titanium, and includes a face portion 10, a crown portion 20, a sole portion 30, and a heel portion. 40, a toe part 50, and a back part 60. The golf club head 100 is assembled with a golf club shaft extending in the direction of the shaft axis S. An angle formed by the shaft axis S and the horizontal axis H when the golf club head 100 is addressed at a predetermined angle is referred to as a “lie angle α”. FIG. 1 shows a state in which the golf club head 100 is divided by a loft angle from a state in which the golf club head 100 is addressed by a predetermined lie angle α. As shown in FIG. 1, the face center FC is located at the center of the face portion 10 in the horizontal direction and the vertical direction, and “the center line between the toe side end and the heel side end of the face outline, It means the “intersection of the center line between the crown side end and the sole side end”. Note that, in the region near the hosel of the face outline FG, it is difficult to determine the boundary between the face portion and the other parts, but it is assumed that they are connected by a moderately rounded curve as shown in FIG.

  3 and 4 are a III-III cross section (vertical cross section) and an IV-IV cross section (horizontal cross section) in FIG. 1, respectively. Referring to FIGS. 3 and 4, golf club head 100 includes a face member 1 and a main body member 2. The face member is made of high-strength titanium, and the main body member 2 is made of Ti-6Al-4V. The thickness T of the face member 1 in the vicinity of the face center is about 3.5 mm. Further, the thickness of the face member 1 at the joint portion between the face member 1 and the main body member 2 is about 2.5 mm, and the thickness of the main body member 2 at the portion is about 2 mm. The face member 1 and the main body member 2 are joined by welding. In addition, the thickness of the main body member 2 at a position away from the face portion 10 is about 0.8 mm.

  With reference to FIG. 3, in the golf club head (type 0) according to the present embodiment, the minimum curvature radius r1 on the outer surface of the golf club head 100 at the boundary between the face portion 10 and the crown portion 20 is 9 mm. The minimum radius of curvature R1 on the inner surface is 10 mm. On the other hand, the minimum curvature radius r2 on the outer surface of the golf club head 100 at the boundary between the face portion 10 and the sole portion 30 is 8 mm, and the minimum curvature radius R2 on the inner surface is 8 mm.

  Referring to FIG. 4, in the golf club head (type 0) according to this embodiment, the minimum curvature radius (r3 or R3) at the boundary portion between the face portion 10 and the heel portion 40, and the face portion 10 The minimum radius of curvature (r4 or R4) at the boundary between the toe portion 50 is 6 mm or more although it is slightly smaller than r1, r2, R1, and R2.

  Next, the effect of expanding the sweet area in the golf club head of the present embodiment will be described. Here, golf club heads according to type 1 and type 2 were prepared as comparative examples.

  In the golf club head according to type 1, the minimum curvature radius on the outer surface of the boundary portion between the face portion and the crown portion is 4.5 mm, and the minimum curvature radius on the inner surface is 5 mm. On the other hand, the minimum curvature radius on the outer surface of the boundary portion between the face portion and the sole portion is 4 mm, and the minimum curvature radius on the inner surface is 5 mm.

  In the golf club head according to type 2, the minimum curvature radius on the outer surface of the boundary portion between the face portion and the crown portion is 1.5 mm, and the minimum curvature radius on the inner surface is 2 mm. On the other hand, the minimum curvature radius on the outer surface of the boundary portion between the face portion and the sole portion is 2.5 mm, and the minimum curvature radius on the inner surface is 3 mm.

  Table 2 shows a comparison of the coefficient of restitution at each position in the face portion of the golf club head (type 0) according to this example and the golf club head (type 1, type 2) according to the comparative example. Further, according to the height of the coefficient of restitution of “SS” in Table 2, each part other than “SS” (“TOE15”, “TOE30”, “HEEL15”, “HEEL30”, Table 3 shows the result of converting the coefficient of restitution of “UP15” and “DOWN15”). Further, Table 4 shows the difference of the converted value at each position of Type 0 and Type 1 with respect to the converted value at each position of Type 2 in Table 3.

  In Tables 2 to 4, “SS” means a sweet spot (a position where the center of gravity of the club head is projected onto the face surface). “TOE15” and “TOE30” mean positions moved 15 mm and 30 mm from the sweet spot to the toe side along the face surface, respectively. “HEEL15” and “HEEL30” "UP15" and "DOWN15" mean positions moved 15mm upward and downward along the face surface from the sweet spot, respectively. ing.

Incidentally, the coefficient of restitution (e) The golf club head (mass: M) quiescent golf ball (mass: m) to collide with, (speed of the ball before impact with the face surface) incidence rate of the ball V _IN Then, the reflection speed (the speed of the ball after the collision with the face surface) V _OUT is measured and calculated from the equation (1).
V _OUT / V _IN = (eM−m) / (M + m) (1)
In addition, as a golf ball, a pinnacle gold LS sold from ACUSHNET COMPANY was stored in a room at about 23 ° C., and the collision speed was set to 48.8 m / s. In addition, when the golf ball collided with the face surface, the club head was fixed so that the ball collided from the normal direction of the face surface in order to achieve rebound to the front.

  Referring to Table 2, in any of types 0, 1, and 2, the coefficient of restitution becomes maximum at the sweet spot. Further, the restitution coefficient of type 1 is higher than the restitution coefficient of type 0, and the restitution coefficient of type 2 is higher than the restitution coefficient of type 1. This is due to the fact that the face area is substantially larger in Type 1 than Type 0 and in Type 2 than Type 1.

  Each value in Table 3 is obtained by converting the repulsion coefficients of “SS” of type 0 to type 2 to 0.8240 and converting values of other parts. A method for calculating the values in Table 3 will be described. For example, the coefficient of restitution (0.8240) is about 0.990 times the coefficient of restitution (0.8320) of “SS” of type 2 in Table 2, so that “TOE30 of type 2 depends on this ratio. When the coefficient of restitution (0.717) is converted, it becomes approximately 0.710. Further, since the coefficient of restitution (0.8240) is about 0.995 times the coefficient of restitution (0.8281) of “SS” of type 1 in Table 2, the “HEEL30 of type 1” according to this ratio. When the coefficient of restitution (0.709) is converted, it is about 0.705.

  The values shown in Table 4 are indicators of how much the reduction in the coefficient of restitution of each part other than “SS” in Type 0 and Type 1 is suppressed compared to Type 2. That is, the values shown in Table 3 show the effect of increasing the radius of curvature at the boundary portion between the face portion and its periphery.

  As shown in Table 4, in Type 0, the coefficient of restitution of each part other than “SS” is improved by about 0.005 to 0.009 (only “DOWN15” is 0.004) compared to Type 2. ing. In Type 1, the coefficient of restitution of each part other than “SS” is improved by about 0.002 to 0.004 (only “HEEL30” is 0.007) compared to Type 2.

  Generally, it is said that when the coefficient of restitution is improved by 0.01, the flight distance is increased by about 1.5 to 2 yards. On the other hand, in order for the golfer to experience the effect relating to the rebound characteristics, the flight distance needs to be extended by at least one yard. Therefore, the coefficient of restitution needs to be improved by at least about 0.005.

  In view of the above, regarding type 0 (R1 to R4: 8 mm to 10 mm), it is possible to experience an improvement in the coefficient of restitution at each part other than “SS”, and regarding type 1 (R1 to R4: 4 mm to 5 mm). It turns out that it is difficult to experience the effect. If the values of R1 to R4 are intermediate between type 0 and type 1, that is, about 6 mm, the coefficient of restitution is improved by about 0.005 and the improvement of the coefficient of restitution in each part other than “SS” is experienced. You can see that

  Even in consideration of the measurement error of the radius of curvature and the manufacturing error of the club head, it can be said that R1 to R4 are preferably 6 mm or more in order to obtain the above-described effect.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a view showing a golf club head according to one embodiment of the present invention. It is the figure which looked at the golf club head shown by FIG. 1 from the direction of arrow II. It is III-III sectional drawing in FIG. It is IV-IV sectional drawing in FIG. It is a figure for demonstrating the relationship between a cross-sectional secondary moment and a curvature radius. It is a figure which shows the relationship between a cross-sectional secondary moment and a curvature radius calculated | required from the model shown in FIG. It is a figure for demonstrating "the minimum curvature radius." FIG. 2 illustrates an outline of a head of a conventional golf club head in a cross section along the face-back direction (part 1). FIG. 3 illustrates an outline of the head in a cross section along the face-back direction of a conventional golf club head (part 2). FIG. 3 illustrates an outline of the head in a cross section along the face-back direction of a conventional golf club head (part 3). FIG. 4 illustrates an outline of the head in a cross section along the face-back direction of a conventional golf club head (part 4). FIG. 5 is a diagram (part 5) illustrating an outline of the head in a cross section along the face-back direction of a conventional golf club head. FIG. 6 illustrates an outline of the head in a cross section along the face-back direction of a conventional golf club head (No. 6). FIG. 7 is a diagram (part 7) illustrating an outline of the head in a cross section along the face-back direction of a conventional golf club head.

Explanation of symbols

  1 face member, 2 body member, 10 face portion, 20 crown portion, 30 sole portion, 40 heel portion, 50 toe portion, 60 back portion, 100 golf club head, 200 plate, 300 fulcrum.

Claims (7)

A golf club head having an outer shell structure,
The face part,
Back part,
A crown portion adjacent to the face portion;
In a cross section along the face-back direction from the face part toward the back part through the face center, the minimum radius of curvature on the outer surface side of the boundary part between the face part and the crown part is 6 mm or more and 20 mm or less. Golf club head. A golf club head having an outer shell structure,
The face part,
Back part,
A sole portion adjacent to the face portion;
In the cross-section along the face-back direction from the face part toward the back part through the face center, the minimum radius of curvature on the outer surface side of the boundary part between the face part and the sole part is 6 mm or more and 20 mm or less. Golf club head. A golf club head having an outer shell structure,
The face part,
Back part,
A crown portion and a sole portion adjacent to the face portion;
In the cross-section along the face-back direction from the face part toward the back part through the face center, the minimum radius of curvature on the outer surface side of the boundary part between the face part and the crown part is 6 mm or more and 20 mm or less, And the golf club head whose minimum curvature radius in the outer surface side of the boundary part of the said face part and the said sole part is 6 mm or more and 20 mm or less. A golf club head having an outer shell structure,
The face part,
A body portion including a portion adjacent to the face portion and a back portion;
A golf club head, wherein a minimum curvature radius on an outer surface side of a boundary portion between the face portion and the main body portion is 6 mm or more and 20 mm or less in all cross sections orthogonal to a boundary line between the face portion and the main body portion.   The golf club head according to claim 1, wherein the minimum curvature radius is 8 mm or more and 12 mm or less.   The golf club head according to claim 1, wherein the minimum radius of curvature on the inner surface side of the golf club head is larger than the minimum radius of curvature on the outer surface side of the golf club head.   A golf club comprising the golf club head according to claim 1.

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