Iron golf club head

Abstract

An iron golf club head comprises a face plate, a head main body and a weight member. The head main body comprises a sole-side frame portion extending from the toe to the heel and provided with a recess which opens toward the face plate and to which the weight member is fixed. The recess is a space between an upper sole wall located above the weight member and a lower sole wall located below the weight member. The lower sole wall comprises a first portion having a support surface supporting the rear surface of the face plate, and a second portion located on the rear side of the first portion. The first portion extends rearward from the support surface beyond the front end of the weight member, forming a gap between the first portion and the weight member. The second portion supports the lower surface of the weight member.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an iron golf club head.BACKGROUND ART

[0002] The following Patent Document 1 discloses an iron golf club head comprising a head main body, a face plate fixed to the head main body and a weight member having a specific gravity greater than the head main body and the face plate.

[0003] Patent Document 1: Japanese Patent No. 7205371SUMMARY OF THE INVENTIONProblems to Be Solved by the Invention

[0004] Iron golf club heads are desired to have lowered gravity center position and improved rebound performance.

[0005] In view of the above circumstances, the present disclosure was devised, and

[0006] a primary objective of the present disclosure is to provide an iron golf club head in which the position of the center of gravity of the head can be lowered, and the COR (coefficient of restitution) can be improved.Means for Solving the Problems

[0007] According to the present disclosure, an iron golf club head has a striking face for striking a ball, a top, a sole, a toe and a heel, and is composed of

[0008] a face plate having a front surface constituting at least a part of the striking face and a rear surface opposite the front surface;

[0009] a head main body to which the face plate is fixed; and

[0010] a weight member fixed to the head main body;wherein

[0011] the weight member has a specific gravity greater than those of the head main body and the face plate,

[0012] the head main body comprises a sole side frame portion extending from the toe to the heel,

[0013] the sole side frame portion is provided with a recess which opens toward the face plate, and to which the weight member is fixed,

[0014] the recess is a space between an upper sole wall located above the weight member and a lower sole wall located below the weight member,

[0015] the lower sole wall comprises a first portion having a support surface supporting the rear surface of the face plate, and a second portion located on the rear side of the first portion;

[0016] the first portion extends rearward from the support surface beyond a front end of the weight member, while forming a gap in the up-down direction of the head between the first portion and the weight member, and

[0017] the second portion contacts and supports the lower surface of the weight member.Effects of the Invention

[0018] In the iron golf club head according to the present disclosure, therefore, by adopting the above-described configuration, it is possible to lower the position of the center of gravity of the head and to improve the rebound performance of the head.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a front view of an iron golf club head as an embodiment of the present disclosure.

[0020] FIG. 2 is a rear view thereof.

[0021] FIG. 3 is a side view thereof as viewed from the toe side.

[0022] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1.

[0023] FIG. 5 is an exploded perspective view of the iron golf club head shown in FIG. 1.

[0024] FIG. 6 is a view of the face plate as viewed from the rear side.

[0025] FIG. 7 is a perspective view of the head main body.

[0026] FIG. 8 is an enlarged cross-sectional view of the sole side frame portion shown in FIG. 4.

[0027] FIG. 9 is an enlarged cross-sectional view showing a first modified example of the sole side frame portion.

[0028] FIG. 10 is an enlarged cross-sectional view showing a second modified example of the sole side frame portion.

[0029] FIG. 11 is an enlarged cross-sectional partial view of another embodiment showing the face plate and the sole side frame portion.

[0030] FIG. 12 shows the results of measuring the COR for the embodiment and a comparative example.

[0031] FIG. 13 is an enlarged cross-sectional view of the sole side frame portion of the comparative example.

[0032] FIG. 14 is a diagram showing the distribution of stress acting on the head main body of each of the embodiment and the comparative example.

[0033] FIG. 15 is a diagram showing the distribution of stress acting on the face plate of each of the embodiment and the comparative example.

[0034] FIG. 16 is a perspective view of an iron golf club head for explaining the reference state of the head.DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Embodiments of the present disclosure will now be described in detail in conjunction with accompanying drawings.

[0036] The drawings may contain exaggerations and dimensional ratios different from the actual ratios in order to aid the understanding of the present disclosure.

[0037] For the different embodiments or examples, the same reference numerals are given to the same or common parts, and duplicate explanations are omitted.

[0038] The specific configurations illustrated in the embodiments and the drawings are for understanding the present disclosure, and the present disclosure is not limited to such specific configurations.

[0039] FIGS. 1, 2 and 3 are a front view, a rear view and a side view from the toe side, respectively, of an iron golf club head 1 as an embodiment of the present disclosure (hereinafter, simply referred to as the head 1).

[0040] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1.

[0041] FIG. 5 is an exploded perspective view of the head 1.

[0042] In FIGS. 1 to 3, the head 1 is under its reference state.Reference State

[0043] In this application including the specification and claims, the “reference state” means a state of a golf club head in which, as shown in FIG. 16, the head is placed on a horizontal plane HP; the center line CL of a shaft inserting hole of a hosel 7 of the head (corresponding to the axis of a club shaft attached to the hosel) lies within a reference vertical plane VP which is a plane perpendicular to the horizontal plane HP; and face lines 8 formed in a striking face 2 of the head become parallel to the horizontal plane HP and parallel to the reference vertical plane VP.

[0044] In this specification and claims, unless otherwise noted, the descriptions relating to the golf club head are made based on the head under its reference state.Directions Relating to Golf Club Head

[0045] In FIG. 16, the golf club head is placed in x-y-z coordinate system associated with the reference state, wherein

[0046] the xy plane corresponds to the horizontal plane HP,

[0047] the yz plane corresponds to the reference vertical plane VP,

[0048] the x axis is parallel to the horizontal plane HP and perpendicular to the reference vertical plane VP, and

[0049] the y axis is parallel to the horizontal plane HP and the reference vertical plane VP.

[0050] The “front-rear direction” of the head is a direction parallel to the x axis,

[0051] the “toe-heel” direction of the head is a direction parallel to the y axis, and

[0052] the “up-down” direction of the head is a direction parallel to the z axis.

[0053] The expression “front side” of the head refers to the side of the striking face 2.

[0054] The expression “rear side” or “back side” of the head refers to the opposite side to the “front side”.

[0055] The expression “upper side” of the head refers to the side away from the horizontal plane HP.

[0056] The expression “lower side” of the head refers to the opposite side to the “upper side”.

[0057] The “lower surface” of the head is referred to as the bottom surface, sole, or sole surface.

[0058] In FIG. 16, α and β are the loft angle and lie angle, respectively, specified for the head.Basic Shape of Golf Club Head

[0059] The head 1 of the present embodiment has a typical iron-type shape as shown in FIGS. 1 to 5, and includes a striking face 2, a top 3, a sole 4, a toe 5, a heel 6 and a hosel 7.

[0060] The striking face 2 is a surface for striking a golf ball and is formed as a flat surface except for the face lines or grooves 8.

[0061] The top 3 is an upper surface portion of the head 1 extending rearward from the upper edge of the striking face 2.

[0062] The top 3 is inclined so that the height from the horizontal plane HP gradually decreases from the toe side toward the heel.

[0063] The sole 4 is a bottom surface portion of the head 1 extending rearward from the lower edge of the striking face 2.

[0064] The toe 5 is a tip portion of the head on the opposite side to the hosel 7 in the toe-heel direction of the head.

[0065] The heel 6 is a portion opposite to the toe 5 in the toe-heel direction of the head.

[0066] The hosel 7 is provided with a hosel bore 7a into which a tip end of the club shaft is fixed.

[0067] By the center line of the hosel bore 7a, the above-mentioned imaginary club shaft axis CL (FIG. 1) is defined.

[0068] The head 1 of the present embodiment is composed of a face plate 100, a head main body 200 to which the face plate 100 is fixed, and a weight member 300 fixed to the head main body 200.Face Plate

[0069] As shown in FIGS. 4 to 6, the face plate 100 in this example is in the form of a thin plate, and the face plate 100 has a front surface 101 that constitutes at least a part of the striking face 2, a rear surface 102 opposite thereto, and an outer peripheral side surface 103 extending between the front surface 101 and the rear surface 102.

[0070] The front surface 101 is provided with the face lines 8 in order to increase the friction between the front surface and the ball.

[0071] The face lines 8 are grooves having small widths and depths, extending parallel to each other. Except for the face lines 8, the front surface 101 is substantially flat.

[0072] The contour shape and size of the face plate 100 are appropriately determined so that the front surface 101 forms the major main part of the striking face 2.

[0073] As shown in FIG. 1, the face plate 100 in the present embodiment is defined by a top side edge 100A, a sole side edge 100B, a toe side edge 100C and a heel side edge 100D.

[0074] In the present embodiment, the top side edge 100A, the sole side edge 100B and the toe side edge 100C each extend to the surface of the top 3, the surface of the sole 4 and the surface of the toe 5, respectively. That is, the front surface 101 of the face plate 100 of the present embodiment forms substantially the entire area of the striking face 2.

[0075] As another example, the top side edge 100A, the sole side edge 100B and the toe side edge 100C of the face plate 100 may terminate before the surface of the top 3, the surface of the sole 4 and the surface of the toe 5, respectively, without reaching the respective surfaces.

[0076] On the other hand, the heel side edge 100D of the face plate 100 in the present embodiment extends vertically along the heel-side end of the striking face 2.

[0077] Preferably, the face plate 100 in this example is made of a metal material.

[0078] Such metal materials are not particularly limited, but preferable are stainless steel, maraging steel, carbon steel, titanium alloy, etc. The face plate 100 of the present embodiment is made of stainless steel.

[0079] As shown in FIG. 4, the face plate 100 comprises a main portion 104 having a thickness ta and including the sweet spot SS (shown in FIG. 1). The thickness ta of the main portion 104 is not particularly limited, but preferably not more than 2.8 mm, more preferably not more than 2.5 mm so as to allow for large elastic deformation when hit by the ball. Further, from the viewpoint of maintaining the durability of the face plate 100, it is preferable that the thickness ta of the main portion 104 is not less than 1.8 mm, for example.

[0080] The face plate 100 of the present embodiment comprise a thin portion 105 having a thickness tb smaller than the thickness ta of the main portion 104.

[0081] The thin portion 105 is formed by locally making a depression in the rear surface 102 of the face plate 100.

[0082] The thin portion 105 makes the face plate 100 more flexible when hit by the ball, and serves to improve the rebound performance of the head 1.

[0083] In order to effectively derive such effect, preferably, the thickness tb of the thin portion 105 is smaller than the thickness ta by not less than 0.3 mm, more preferably not less than 0.4 mm, still more preferably not less than 0.5 mm.

[0084] The thin portion 105 is formed at least at one location on the face plate 100, preferably at a plurality of locations as shown in FIG. 6.

[0085] In the present embodiment, the thin portion 105 includes all of a top side thin portion 105A, a sole side thin portion 105B and a toe side thin portion 105C. But, the thin portion 105 may be formed to include at least one of these.

[0086] The top side thin portion 105A extends, for example, along the top side edge 100A of the face plate 100 in the toe-heel direction.

[0087] The sole side thin portion 105B extends, for example, along the sole side edge 100B of the face plate 100 in the toe-heel direction.

[0088] The toe side thin portion 105C extends vertically while curving along the toe side edge 100C of the face plate 100.

[0089] The thin portions 105A, 105B and 105C are arranged to surround the sweet spot SS.

[0090] In the present embodiment, the thin portions 105A, 105B and 105C are separated from each other.

[0091] As another example, each of the thin portions 105A, 105B and 105C may be connected to one another.Head Main Body

[0092] The head main body 200 is preferably made of a metal material or materials.

[0093] Such metal materials are not particularly limited, but preferable are stainless steel, maraging steel, carbon steel, titanium alloy, etc.

[0094] The metal material forming the head main body 200 may be the same as the metal material forming the face plate 100, or may be different.

[0095] From a manufacturing standpoint, it is desirable that the metallic materials of these components are weldable to one another.

[0096] The head main body 200 of the present embodiment is made of stainless steel, similar to the face plate 100.

[0097] As shown in FIGS. 4 and 5, the head main body 200 comprises a frame portion 201 and the hosel 7.

[0098] The frame portion 201 includes a top side frame portion 201A, a sole side frame portion 201B, a toe side frame portion 201C, and a heel side frame portion 201D.

[0099] The above-mentioned hosel 7 is integrated with the heel side frame portion 201D.

[0100] In the present embodiment, the frame portion 201 has a through hole C penetrating in the front-rear direction of the head.

[0101] The top side frame portion 201A, the sole side frame portion 201B, the toe side frame portion 201C and the heel side frame portion 201D are continuous in an annular shape so as to surround the through hole C.

[0102] To the top side frame portion 201A, the sole side frame portion 201B, the toe side frame portion 201C and the heel side frame portion 201D, the peripheral edge portion of the face plate 100 is connected.

[0103] In the present embodiment, the sole side frame portion 201B, the toe side frame portion 201C, and the heel side frame portion 201D have respective support surfaces 202 supporting the rear surface 102 of the face plate 100.

[0104] The support surfaces 202 are formed in a plane parallel to the rear surface 102 of the face plate 100.

[0105] The support surfaces 202 in the present embodiment extend in an annular shape surrounding the through hole C.

[0106] In the present embodiment, the peripheral edge portion of the rear surface 102 of the face plate 100 is fitted onto the support surfaces 202 of the frame portion 201, and

[0107] the edges of the rear surface 102 and the support surfaces 202 are fixed by welding.

[0108] The welding is merely an example of the method of fixing the face plate 100 to the frame portion 201, and the fixing method is not particularly limited. The peripheral edge portion of the rear surface 102 of the face plate 100 comes into contact with the head main body 200, but the other portion does not come into contact with the head main body 200, and faces the through hole C. Therefore, the face plate 100 can deflect or bend significantly toward the rear of the head when hit by a ball. This serves to improve the rebound performance of the head 1.

[0109] The sole side frame portion 201B extends from the toe to the heel below the through hole C.

[0110] In the sole side frame portion 201B in the present embodiment, there is formed a recess 204 opening toward the face plate 100. The recess 204 will be described in detail later.Weight Member

[0111] The weight member 300 has a specific gravity greater than that of the head main body 200 and that of the face plate 100.

[0112] The weight member 300 is made of, for example, a metal material with a high specific gravity.

[0113] The weight member 300 of the present embodiment is made of an alloy containing tungsten and nickel.

[0114] Further, the weight member 300 of the present embodiment has, for example, a block shape that is long in the toe-heel direction. The shape of the weight member 300 is however not particularly limited.

[0115] The position of the weight member 300 in the toe-heel direction is not particularly limited. But, as shown in FIG. 1, the weight member 300 is preferably disposed below the face center FC.

[0116] Here, the face center FC is the center between the toe side end and the heel side end of the longest face line 8, and is also the center in the up-down direction of the head along the striking face 2.

[0117] Preferably, the weight member 300 of the present embodiment is offset toward the toe side from the face center FC.

[0118] Specifically, the center position in the toe-heel direction, of the weight member 300 is located on the toe side of the face center FC.

[0119] In general, the sweet spot of an iron golf club head tends to be located on the heel side of the face center FC due to the presence of the hosel 7 and other factors.

[0120] The weight member 300 which is offset as described above can distribute more weight to the toe side of the head 1, which can move the sweet spot SS closer to or coincident with the face center FC.

[0121] Here, the sweet spot SS is the point of intersection of the striking face 2 and a straight line drawn normally to the striking face 2 from the center of gravity of the head.Recess of Sole Side Frame Portion

[0122] FIG. 7 is a perspective view of the head main body 200. FIG. 8 is an enlarged cross-sectional view of the sole side frame portion 201B shown in FIG. 5.

[0123] As shown in FIGS. 7 and 8, the recess 204 provided in the sole side frame portion 201B is open toward the face plate100.

[0124] The recess 204 is formed as a space between an upper sole wall 206 located above the weight member 300 and a lower sole wall 208 located below the weight member 300.

[0125] The upper sole wall 206 forms the upper surface of the sole side frame portion 201B and extends in the toe-heel direction.

[0126] The lower sole wall 208 forms the lower surface (sole 4) of the sole side frame portion 201B and extends in the toe-heel direction.

[0127] The upper sole wall 206 and the lower sole wall 208 are connected to each other at the rear of the head.

[0128] Therefore, the recess 204 in this example is closed on the rear side of the head and is opened toward the face plate 100.

[0129] As a result, the vertical cross section of the recess 204 is tapered such that the height of the space gradually decreases toward the rear of the head as shown in FIG. 8.

[0130] The weight member 300 is fixed to the recess 204.

[0131] For example, before the face plate 100 is attached to the head main body 200, the weight member 300 is inserted and fixed to the recess 204.

[0132] As shown in FIG. 8, the weight member 300 has a vertical cross section shape which corresponds to the vertical cross section shape of the recess 204 and is tapered toward the rear of the head.

[0133] The method of fixing the weight member 300 is not particularly limited, and various methods such as welding, brazing, caulking, screws and the like can be used.

[0134] After the weight member 300 is fixed to the head main body 200, the face plate 100 is fixed to the head main body 200.

[0135] Between the front end 301 of the weight member 300 and the rear surface 102 of the face plate 100, a gap is formed in order that the weight member 300 and the face plate 100 do not come into contact with each other when the face plate 100 is elastically deformed toward the rear of the head upon striking a ball.

[0136] The lower sole wall 208 comprises a first portion 209 having the above-mentioned support surfaces 202 for the rear surface 102 of the face plate 100, and a second portion 210 located behind the first portion 209.

[0137] The first portion 209 extends from the support surfaces 202 to a position rearward of the above-mentioned front end 301 of the weight member 300.

[0138] Specifically, the first portion 209 extends so as to reach a region which is formed by projecting the weight member 300 downward in a direction perpendicular to the horizontal plane HP. And, between the first portion 209 and the weight member 300, there is formed a gap in the up-down direction of the head.

[0139] On the other hand, the second portion 210 contacts and supports the lower surface of the weight member 300.

[0140] As a result, the lower surface of the weight member 300 includes a second lower surface 302 and a first lower surface 303, wherein the second lower surface 302 contacts the second portion 210, and the first lower surface 303 protrudes from the second portion 210 toward the front of the head without contacting with the head main body 200 and thus being not supported by the head main body 200.

[0141] In the present embodiment, the first lower surface303 and the second lower surface 302 are smoothly continuous.Operation of the Present Embodiment

[0142] In the head 1 of the present embodiment, as the weight member 300 having a high specific gravity is disposed in the sole side frame portion 201B, the position of the center of gravity of the head can be lowered.

[0143] Further, as the first portion 209 of the lower sole wall 208 extends from the support surfaces 202 to a position beyond the front end 301 of the weight member 300 toward the rear of the head without coming into contact with the weight member 300, the first portion 209 of the sole side frame portion 201B can flex when striking a ball, over a wider range in the front-rear direction of the head without being restricted by the weight member 300.

[0144] This can improve the rebound performance of the head 1 (particularly, the rebound performance when the sole 4 side portion of the striking face 2 is hit by the ball).

[0145] The iron golf clubs are often used to strike a ball placed directly on the ground, therefore, it is effective for the iron golf club heads to improve the rebound performance when the sole 4 side portion of the striking face 2 is hit by the ball.

[0146] Hereinafter, further preferable features for the embodiment of the present disclosure will be described.First Portion

[0147] As shown in FIG. 8, the gap (d) between the first portion 209 and the weight member 300 in the vertical direction is preferably not less than 0.2 mm, more preferably not less than 0.4 mm in order to certainly prevent the contact between the weight member 300 and the first portion 209 elastically deformed when hit by the ball.

[0148] On the other hand, by reducing the gap (d), the weight member 300 can be positioned further downward, and as a result, the position of the center of gravity of the head is further lowered. From this viewpoint, it is preferable that the gap (d) is not more than 1.5 mm, more preferably not more than 0.8 mm.

[0149] The first portion 209 preferably includes a gradually decreasing thickness portion 209a as shown in FIG. 8.

[0150] The gradually decreasing thickness portion 209a is such that the thickness thereof gradually decreases from the position of the support surfaces 202 toward the rear of the head.

[0151] The thickness of the gradually decreasing thickness portion 209a in this example continuously decreases from a first thickness t1 to a second thickness t2. But, the thickness may be decreased stepwise.

[0152] By the provision of such gradually decreasing thickness portion 209a, the first portion 209 can bend effectively when hit by the ball.

[0153] The stress applied to the lower sole wall 208 when hit by the ball is highest at the support surfaces 202 as the joint with the face plate 100, and gradually decreases therefrom toward the rear of the head.

[0154] The gradually decreasing thickness portion 209a has a thickness distribution corresponding to such stress distribution so that positions at which higher stress acts have greater thickness.

[0155] As a result, the stress acting on the first portion 209 when hit by the ball is not concentrated at a specific position, but is dispersed widely in the front-rear direction of the head.

[0156] Thus, the gradually decreasing thickness portion 209a serve to improve the durability of the head 1.

[0157] The first thickness t1 is not particularly limited, but preferably not more than 3.0 mm, more preferably not more than 2.5 mm, from the viewpoint of effectively deflecting the first portion 209 of the lower sole wall 208 when hit by the ball.

[0158] On the other hand, from the viewpoint of ensuring sufficient durability of the first portion 209, the first thickness t1 is preferably not less than 1.5 mm, more preferably not less than 2.0 mm.

[0159] The second thickness t2 is also not particularly limited, but preferably not more than 2.5 mm, more preferably not more than 2.0 mm, from the viewpoint of effectively deflecting the first portion 209 of the lower sole wall 208 when hit by the ball.

[0160] On the other hand, from the viewpoint of ensuring sufficient durability of the first portion 209, the second thickness t2 is preferably not less than 0.7 mm, more preferably not less than 1.0 mm.

[0161] The first portion 209 in this example includes a constant thickness portion 209b which extends substantially continuously toward the rear of the head with the second thickness t2 from the gradually decreasing thickness portion 209a.

[0162] Such constant thickness portion 209b serves to further increase the durability of the first portion 209.

[0163] As shown in FIG. 4, the dimension (A) in the front-rear direction, of the first portion 209 of the lower sole wall 208 is not particularly limited, but from the viewpoint of effectively bending the first portion 209 when hit by the ball, the dimension (A) is preferably not less than 4 mm, more preferably not less than 5 mm.

[0164] On the other hand, from the viewpoint of ensuring sufficient durability of the first portion 209, the dimension (A) of the first portion 209 is preferably not more than 10 mm, more preferably not more than 8 mm.

[0165] The dimension (B) in the front-rear direction, of the gradually decreasing thickness portion 209a of the first portion 209 is not particularly limited, but from the same viewpoints as the dimension (A), it is preferably not less than 2 mm, more preferably not less than 4 mm, but preferably not more than 8 mm, more preferably not more than 6 mm.

[0166] As shown in FIG. 7, the upper sole wall 206 in this example has an end 206a in the toe-heel direction located at a position on the heel side of the face center FC in the toe-heel direction.

[0167] At the end 206a, there is provided a side wall portion 207 that constrains the heel side end of the weight member 300.

[0168] The side wall portion 207 defines the heel side end of the recess 204.

[0169] The side wall portion 207 in this example extends downward from the upper sole wall 206 and terminates without reaching the lower sole wall 208.

[0170] The toe side end of the recess 204 is defined by the toe side frame portion 201C.

[0171] The lower sole wall 208 in this example extends beyond the end 206a of the upper sole wall 206 toward the heel, and in this example, extends to the heel side frame portion 201D.

[0172] Therefore, the lower sole wall 208 in this example continues to the heel side frame portion 201D, while maintaining the cross-sectional shape shown in FIG. 4.

[0173] The area in which the lower sole wall 208 is formed is not particularly limited, but it is preferable that the lower sole wall 208 is formed over the entire area in the toe-heel direction in which the weight member 300 is disposed.Second Portion

[0174] The second portion 210 supports the lower surface of the weight member 300 as show in FIG. 8.

[0175] Specifically, the second portion 210 supports the second lower surface 302 which is a part on the rear side of the head, of the lower surface of the weight member 300.

[0176] The first lower surface 303, which is a part of the lower surface of the weight member 300 on the front side of the head, is located above the first portion 209.

[0177] In the present embodiment, the second portion 210 has a thickness t3 (hereinafter referred to as the third thickness) that is greater than the second thickness t2 of the first portion 209.

[0178] Such second portion 210 helps to increase the durability of the lower sole wall 208.

[0179] In the present embodiment, the outer surface of the sole 4 is formed as a smoothly curved surface.

[0180] Therefore, the first portion 209 and the second portion 210 are connected via a step surface 211 so as to bridge between the third thickness t3 of the second portion 210 and the second thickness t2 of the first portion 209. The step surface 211 extends in the vertical direction of the head.Modification 1

[0181] FIG. 9 is a cross-sectional view of a first modified example of the sole side frame portion 201B taken at a position corresponding to that of the cross-section shown in FIG. 4.

[0182] In this example, the lower sole wall 208 is the same as that of the example shown in FIG. 4. But, the upper sole wall 206 is different from that of the example shown in FIG. 4. The joint surface J between the weight member 300 and the upper sole wall 206 terminates rearward of the front surface of the weight member 300.

[0183] Thus, the weight member 300 protrudes forward of the head from the front end 206b of the upper sole wall 206 and from the step surface 211.

[0184] Therefore, front portions of the lower and upper surfaces of the weight member 300 protrude from the recess 204.

[0185] In this example, the weight of the upper sole wall 206 is reduced, creating new weight margin that can be used arbitrarily within the limited weight of the head 1.

[0186] Such a weight margin allows the weight member 300 to be made larger, and allows for the weight distribution design to further distribute the weight to other locations.Modification 2

[0187] FIG. 10 is a cross-sectional view of a second modified example of the sole side frame portion 201B taken at a position corresponding to that of the cross-section shown in FIG. 4.

[0188] In this example, the first portion 209 and the second portion 210 of the lower sole wall 208 are connected smoothly without any steps on both the upper and lower surfaces.

[0189] On the other hand, the lower surface of the weight member 300 has

[0190] the second lower surface 302 that contacts (is supported by) the second portion 210,

[0191] the first lower surface 303 that is located above the first portion 209 without contacting therewith, and

[0192] a step surface 304 that connects between the second lower surface 302 and the first lower surface 303 bridging the height difference therebetween.

[0193] In this example, compared to the example shown in FIG. 4, it is possible to position the weight member 300 further below the head so as to further lower the position of the center of gravity of the head.Another Embodiment

[0194] FIG. 11 is an enlarged cross-sectional partial view of another embodiment of the present disclosure showing modified examples of the sole side frame portion 201B and the face plate 100, taken at a position corresponding to that of the cross-section shown in FIG. 4.

[0195] In this embodiment, the sole side edge 100B of the face plate 100 is located higher than the sole 4 as compared to the former examples. The face plate 100 is fixed to the head main body 200 by caulking. Specifically, the sole side frame portion 201B is provided with a receiving portion 220 for the sole side edge 100B, and

[0196] a part of the receiving portion 220 is plastically deformed so as to hold the peripheral edge portion of the front surface of the face plate 100 as shown in FIG. 11.

[0197] Further, the sole side frame portion 201B is provided with a support surfaces 202 that extends upward from the receiving portion 220 and supports the back surface of a sole side edge 100B portion of the face plate 100.

[0198] In the present embodiment, a gap in the up-down direction of the head is formed between the first portion 209 and the weight member 300.

[0199] While detailed description has been made of preferable embodiments of the present disclosure, the present disclosure can be embodied in various forms without being limited to the illustrated embodiments.Comparison Tests

[0200] FIG. 12 shows the results of measuring the coefficient of restitution (COR) for an embodiment (EMB) and a comparative example (COM).

[0201] The embodiment was the head 1 described above in conjunction with FIGS, 1 to 7.

[0202] The comparative example was a head having the same structure as the embodiment except for a sole side frame portion of which structure is shown in FIG. 13.

[0203] Incidentally, the COR is the value obtained by dividing the initial velocity of the rebounding ball by the head speed just before impact with the ball, wherein the larger the value, the better the rebound performance.

[0204] In FIG. 12, the vertical axis of the graph indicates the COR value, and the horizontal axis indicates the ball striking position on the striking face, and the meanings of the symbols used therein are as follows.

[0205] FC: Face Center

[0206] SS: Sweet Spot

[0207] SS T 10: 10 mm toward the toe from the sweet spot

[0208] SS T 5: 5 mm toward the toe from the sweet spot

[0209] SS H 5: 5 mm toward the heel from the sweet spot

[0210] SS H 10: 10 mm towards the heel from the sweet spot

[0211] As is clear from FIG. 12, it was confirmed that, as compared to the comparative example, the embodiment had superior rebound performance (higher COR).

[0212] Next, using computer simulation, the stress distribution in the head main body of each of the embodiment and the comparative example when hit by the ball was obtained.

[0213] FIG. 14 shows a stress contour diagram of each of the embodiment and the comparative example in which the magnitude of stress at various locations of the head main body is visualized using a color-coded contour plot.

[0214] In this diagram, the weight member is hidden for clarity.

[0215] The original of this diagram is in color, but in this patent drawing it has been converted to grayscale.

[0216] From the simulation results, as shown in the stress contour diagrams, the maximum stress acting on the lower sole wall was 1470 MPa in the case of the comparative example, whereas in the case of the embodiment, it was reduced to 1327 MPa, and the stress was distributed over a wide range.

[0217] Similarly, using computer simulation, the stress distribution in the face plate of each of the embodiment and the comparative example when hit by the ball was obtained. The obtained stress distributions are shown in the stress contour diagrams shown in FIG. 15.

[0218] From the simulation results, the maximum stress of the face plate occurring at the joint surface supported by the support surface of the head main body was 1443 MPa in the case of the comparative example, whereas in the case of the embodiment, it was reduced to 1092 MPa, and the stress was distributed over a wide area.STATEMENT OF THE PRESENT DISCLOSURE

[0219] The present disclosure is as follows.[Present Disclosure 1]

[0220] An iron golf club head having a striking face for striking a ball, a top, a sole, a toe and a heel, and composed of

[0221] a face plate having a front surface constituting at least a part of the striking face and a rear surface opposite the front surface;

[0222] a head main body to which the face plate is fixed; and

[0223] a weight member fixed to the head main body;wherein

[0224] the weight member has a specific gravity greater than those of the head main body and the face plate,

[0225] the head main body comprises a sole side frame portion extending from the toe to the heel,

[0226] the sole side frame portion is provided with a recess which opens toward the face plate, and to which the weight member is fixed,

[0227] the recess is a space between an upper sole wall located above the weight member and a lower sole wall located below the weight member,

[0228] the lower sole wall comprises a first portion having a support surface supporting the rear surface of the face plate, and a second portion located on the rear side of the first portion;

[0229] the first portion extends rearward from the support surface beyond a front end of the weight member, while forming a gap in the up-down direction of the head between the first portion and the weight member, and

[0230] the second portion contacts and supports the lower surface of the weight member.[Present Disclosure 2]

[0231] The iron golf club head according to Present Disclosure 1, wherein the gap is not less than 0.2 mm.[Present Disclosure 3]

[0232] The iron golf club head according to the present disclosure 1 or 2, wherein the first portion includes a gradually decreasing thickness portion whose thickness gradually decreases rearward from the support surface, from a first thickness to a second thickness.[Present Disclosure 4]

[0233] The iron golf club head according to Present Disclosure 3, wherein the first portion includes a constant thickness portion at the rear of the gradually decreasing thickness portion which is substantially continuous toward the rear of the head while having the second thickness.[Present Disclosure 5]

[0234] The iron golf club head according to Present Disclosure 3 or 4, wherein the second thickness is in a range from 0.7 to 2.0 mm.[Present Disclosure 6]

[0235] The iron golf club head according to any one of Present Disclosures 1 to 5, wherein a gap is formed between the front end of the weight member and the rear surface of the face plate.[Present Disclosure 7]

[0236] The iron golf club head according to any one of Present Disclosures 1 to 6, wherein the lower sole wall has a step surface extending between the first portion and the second portion.[Present Disclosure 8]

[0237] The iron golf club head according to any one of Present Disclosures 1 to 6, wherein upper surfaces of the first portion and the second portion are connected smoothly without any steps therebetween, and

[0238] the lower surface of the weight member includes a second lower surface which contacts with the second portion, a first lower surface which is positioned above the first portion while forming a gap between the first portion and the first lower surface, and a step surface connecting between the second lower surface and the first lower surface.DESCRIPTION OF THE REFERENCE SIGNS1 head

[0240] 2 striking face

[0241] 3 top

[0242] 4 sole

[0243] 5 toe

[0244] 6 heel

[0245] 100 face plate

[0246] 101 front surface

[0247] 102 rear surface

[0248] 200 head main body

[0249] 201 frame portion

[0250] 201B sole side frame portion

[0251] 202 support surface

[0252] 204 recess

[0253] 206 upper sole wall

[0254] 206b front end

[0255] 208 lower sole wall

[0256] 209 first portion

[0257] 209a gradually decreasing thickness portion

[0258] 209b constant thickness portion

[0259] 210 second portion

[0260] 211 step surface

[0261] 300 weight member

[0262] 301 front end

[0263] 302 second lower surface

[0264] 303 first lower surface

[0265] 304 step surface

Claims

1. An iron golf club head having a striking face for striking a ball, a top, a sole, a toe and a heel, and composed ofa face plate having a front surface constituting at least a part of the striking face and a rear surface opposite the front surface;a head main body to which the face plate is fixed; anda weight member fixed to the head main body;wherein the weight member has a specific gravity greater than those of the head main body and the face plate,the head main body comprises a sole side frame portion extending from the toe to the heel,the sole side frame portion is provided with a recess which opens toward the face plate, and to which the weight member is fixed,the recess is a space between an upper sole wall located above the weight member and a lower sole wall located below the weight member,the lower sole wall comprises a first portion having a support surface supporting the rear surface of the face plate, and a second portion located on the rear side of the first portion;the first portion extends rearward from the support surface beyond a front end of the weight member, while forming a gap in the up-down direction of the head between the first portion and the weight member, andthe second portion contacts and supports the lower surface of the weight member.

2. The iron golf club head according to claim 1, whereinthe gap is not less than 0.2 mm.

3. The iron golf club head according to claim 1, whereinthe first portion includes a gradually decreasing thickness portion whose thickness gradually decreases rearward from the support surface, from a first thickness to a second thickness.

4. The iron golf club head according to claim 2, whereinthe first portion includes a gradually decreasing thickness portion whose thickness gradually decreases rearward from the support surface, from a first thickness to a second thickness.

5. The iron golf club head according to claim 3, whereinthe first portion includes a constant thickness portion at the rear of the gradually decreasing thickness portion which is substantially continuous toward the rear of the head while having the second thickness.

6. The iron golf club head according to claim 3, whereinthe second thickness is in a range from 0.7 to 2.0 mm.

7. The iron golf club head according to claim 5, whereinthe second thickness is in a range from 0.7 to 2.0 mm.

8. The iron golf club head according to claim 1, whereina gap is formed between the front end of the weight member and the rear surface of the face plate.

9. The iron golf club head according to claim 1, whereinthe lower sole wall has a step surface extending between the first portion and the second portion.

10. The iron golf club head according to claim 3, whereinthe lower sole wall has a step surface extending between the first portion and the second portion.

11. The iron golf club head according to claim 5, whereinthe lower sole wall has a step surface extending between the first portion and the second portion.

12. The iron golf club head according to claim 6, whereinthe lower sole wall has a step surface extending between the first portion and the second portion.

13. The iron golf club head according to claim 1, whereinupper surfaces of the first portion and the second portion are connected smoothly without any steps therebetween, andthe lower surface of the weight member includesa second lower surface which contacts with the second portion,a first lower surface which is positioned above the first portion while forminga gap between the first portion and the first lower surface, anda step surface connecting between the second lower surface and the first lower surface.

14. The iron golf club head according to claim 3, whereinupper surfaces of the first portion and the second portion are connected smoothly without any steps therebetween, andthe lower surface of the weight member includesa second lower surface which contacts with the second portion,a first lower surface which is positioned above the first portion while forminga gap between the first portion and the first lower surface, anda step surface connecting between the second lower surface and the first lower surface.

15. The iron golf club head according to claim 5, whereinupper surfaces of the first portion and the second portion are connected smoothly without any steps therebetween, andthe lower surface of the weight member includesa second lower surface which contacts with the second portion,a first lower surface which is positioned above the first portion while forminga gap between the first portion and the first lower surface, anda step surface connecting between the second lower surface and the first lower surface.

16. The iron golf club head according to claim 6, whereinupper surfaces of the first portion and the second portion are connected smoothly without any steps therebetween, andthe lower surface of the weight member includesa second lower surface which contacts with the second portion,a first lower surface which is positioned above the first portion while forminga gap between the first portion and the first lower surface, anda step surface connecting between the second lower surface and the first lower surface.

17. The iron golf club head according to claim 1, whereinthe upper sole wall and the lower sole wall are connected to each other so that the recess is closed on a rear side of the head and has a vertical cross section tapered toward the rear side of the head.

18. The iron golf club head according to claim 1, whereinthe upper sole wall extends toward the face plate beyond a front surface of the weight member and terminates without reaching the face plate.

19. The iron golf club head according to claim 1, whereinthe upper sole wall extends toward the face plate and terminates without protruding from a front surface of the weight member.

20. The iron golf club head according to claim 1, whereina side wall portion which defines a heel side end of the recess is formed so as to extend downward from an end in the toe-heel direction of the upper sole wall located at a position on the heel side of a face center in the toe-heel direction, and terminates without reaching the lower sole wall.

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