Golf club head

Abstract

An iron-type golf club head comprises a face portion having a striking face having an imaginary impact point which is located on a vertical line passing through the midpoint in the toe-heel direction between a toe side end and a heel side end of the face lines and 18 mm above from the lower end of the striking face. The face portion includes a thin portion having a first thickness of 2.0 to 4.0 mm and a thick portion having a second thickness being at least 4.0 mm and larger than the first thickness by at least 1.0 mm. The thin portion is formed within an imaginary circle of 10 mm radius centered on the imaginary impact point. The thick portion surrounds the thin portion and forms at least the range of an imaginary circle of 15 mm radius centered on the imaginary impact point.

Description

TECHNICAL FIELD

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

[0002] When a golf ball is hit with an iron golf club, the impact force generated by the collision between the ball and the golf club head is transmitted to the player's hands via the shaft and grip.

[0003] Generally, the sensation of vibrations and impacts that the player's hands experience is called the feel of the hit (hereinafter, the “hit feel” for short).

[0004] For professionals and advanced golfers (equivalent to a single handicap), the hit feel is one of the most important performance characteristics of a golf club.

[0005] In order to improve the hit feel of iron-type golf club heads, various devices have been made.

[0006] For example, Patent Document 1 listed below discloses an iron-type golf club head whose face portion is provided, on its back side facing a cavity, with a protrusion so as to partially increase the thickness of the face portion.

[0007] In this golf club head, the protrusion improves the bending rigidity of the face portion, therefore, it is expected to provide an excellent hit feel with less vibration when hit by the ball.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-187342SUMMARY OF THE INVENTIONProblems to be Solved by the Invention

[0009] In the golf club head disclosed in Patent Document 1, despite the good hit feel, there is a possibility that the moment of inertia (MOI) around a vertical axis passing through the center of gravity of the head (hereinafter, such a moment of inertia is referred to as the right-left MOI) is liable to become small since the weight of the golf club head is concentrated at a position near the typical ball hitting positions on the striking face.

[0010] Further, when the right-left MOI is small, such a head lacks forgiveness on mishits, which means that the flight direction of the ball on mishits is likely to deviate from the target or intended direction.

[0011] In view of the problems described above, the present disclosure was made, and a primarily objective of the present disclosure is to provide a golf club head in which the forgiveness on mishits can be improved while preventing a deterioration in the hit feel.Means for Solving the Problems

[0012] According to the present disclosure, an iron-type golf club head comprises:

[0013] a face portion comprising a striking face for striking a ball, and an imaginary impact point set on the striking face,

[0014] the striking face being provided with face lines extending in a toe-heel direction of the head, and

[0015] in a vertical state of the head in which the striking face is vertical and the face lines are horizontal, the imaginary impact point is defined as a point which is positioned on a vertical line passing through the midpoint in the toe-heel direction between a toe side end and a heel side end of the face lines, and which is located 18 mm above from a lower end of the striking face,wherein

[0016] the face portion includes a thin portion having a first thickness, and a thick portion having a second thickness larger than the first thickness,

[0017] the first thickness is in a range from 2.0 to 4.0 mm,

[0018] the second thickness is not less than 4.0 mm and larger than the first thickness by at least 1.0 mm,

[0019] the thin portion is formed within a range of an imaginary circle of 10.0 mm radius centered on the imaginary impact point, and

[0020] the thick portion surrounds the thin portion on the outside thereof and forms at least a range of an imaginary circle of 15 mm radius centered on the imaginary impact point.Effects of the Invention

[0021] In the present disclosure, therefore, the golf club head can be improved in forgiveness on mishits while preventing the deterioration in the hit feel.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a front view of a golf club head as an embodiment of the present disclosure under its reference state.

[0023] FIG. 2 is a rear view thereof.

[0024] FIG. 3 is a side view thereof from the toe side.

[0025] FIG. 4 is a perspective view thereof from the rear and toe side.

[0026] FIG. 5 is a side view of the golf club head under its vertical state, viewed from the toe side.

[0027] FIG. 6 is a front view of the golf club head under the vertical state.

[0028] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6.

[0029] FIG. 8 is a diagram for illustrating the contact area between the striking face and the ball.

[0030] FIG. 9 is a front view of a golf club head under its vertical state showing another example of the thin portion.

[0031] FIG. 10 is a perspective view for explaining the reference state of a golf club head.DETAILED DESCRIPTION OF THE INVENTION

[0032] Embodiments of the present disclosure will now be described in detail in conjunction with accompanying drawings.

[0033] The drawings may contain exaggerations and dimensional ratios different from the actual ratios in order to aid the understanding of the present disclosure.

[0034] For the different embodiments, the same reference numerals are given to the same or common parts, and redundant explanations are omitted.

[0035] 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.

[0036] FIGS. 1 to 4 are respectively a front view, a rear view, a side view from the toe side, and a perspective view of an iron-type golf club head 1 (hereinafter simply referred to as the head 1) as an embodiment of the present disclosure placed in its reference state.<Reference State>

[0037] In this application, as shown in FIG. 10, the “reference state” of a golf club head means a state in which the head is placed on a horizontal plane HP so that face lines 7 formed on a striking face 3 of the head become parallel to the horizontal plane HP, and the center line CL of a shaft insertion hole 9a of the head (corresponding to the axis of the club shaft attached) lies within a reference vertical plane VP perpendicular to the horizontal plane HP.

[0038] In this reference state, the face lines 7 are parallel to the horizontal plane HP and also parallel to the reference vertical plane VP.

[0039] The angle between the center line CL of the shaft insertion hole 9a (the axis of the club shaft) and the horizontal plane HP is the lie angle α specified for the head, and the angle between the striking face 3 and the reference vertical plane VP is the loft angle β specified for the head.

[0040] In this application including the specification and claims, descriptions are made based on the head placed in its reference state unless otherwise noted.<Directions Regarding Club Head>

[0041] As shown in FIG. 10, in which a golf club head under its reference state is placed in the xyz Cartesian coordinate system, wherein

[0042] the xy plane corresponds to the horizontal plane HP,

[0043] the yz plane corresponds to the reference vertical plane VP,

[0044] the x axis is parallel to the horizontal plane HP and perpendicular to the reference vertical plane VP, and

[0045] the y axis is parallel to the horizontal plane HP and the reference vertical plane VP,

[0046] the “front-back direction” of the head is a direction parallel to the x axis,

[0047] the “toe-heel” direction of the head is a direction parallel to the y axis, and

[0048] the “up-down” direction of the head is a direction parallel to the z axis.

[0049] The expression “front side” of the head refers to the side of the striking face,

[0050] the expression “rear side” or “back side” of the head refers to the opposite side to the “front side”,

[0051] the expression “upper side” of the head refers to the side away from the horizontal plane HP, and

[0052] the expression “lower side” of the head refers to the opposite side to the “upper side”.<Vertical State>

[0053] In this application, a vertical state of a golf club head 1 is further defined.

[0054] The “vertical state” of a golf club head refers to such a state that the head in the reference state is rotated around an axis parallel to the toe-heel direction while being placed on the horizontal plane HP so that the striking face is tilted forward by the loft angle β so the angle between the striking face and the reference vertical plane VP becomes zero.

[0055] Even in the vertical state, the “front-back direction”, “toe-heel direction” and “up-down direction” refer to those defined in the above-described coordinate system associated with the reference state unless otherwise noted.

[0056] FIG. 5 is a side view of the head 1 in its vertical state as viewed from the toe side.

[0057] FIG. 6 is a front view of the head 1 in its vertical state.

[0058] In the vertical state of the head 1, the striking face 3 is vertical and the face lines 7 are horizontal.<Basic Head Structure>

[0059] As shown in FIGS. 1 to 6, the head 1 comprises a face portion 2 having the striking face 3 for striking a ball, and a hosel 9.

[0060] In the present embodiment, the head 1 has a one-piece structure made of a metal material. All portions of the head 1 are integrally formed by, for example, forging, casting or other methods.

[0061] But, it is also possible to configure the head to have a multi-piece structure made up of a plurality of parts separately formed and then assembled.

[0062] Metal materials suitable for forming the head 1 include soft iron and stainless steel, for example.

[0063] The face portion 2 has a back face 4 opposite to the striking face 3, and an imaginary impact point 10 is defined on the striking face 3 (see FIG. 6).

[0064] Further, the face portion 2 of the present embodiment includes a top 5, a sole 6, a toe T and a heel H.

[0065] The striking face 3 is a substantially flat surface for striking the ball.

[0066] The striking face 3 is provided with face lines 7 or narrow grooves in order to increase the friction with the ball.

[0067] The face lines 7 extend parallel to the toe-heel direction of the head.

[0068] The face lines 7 are formed in the main hitting area as shown in FIG. 1. In other words, the area between the most toe side end 7a and the most heel side end 7b of the face lines 7 corresponds to the main hitting area.

[0069] The imaginary impact point 10 (shown in FIG. 6) corresponds to the most common impact position when a ball put on turf is struck with an iron-type golf club head by professionals and advanced golfers.

[0070] This imaginary impact point 10 was determined statistically from the results of numerous actual test shots.

[0071] Specifically, as shown in FIG. 6, when the head 1 under the vertical state is viewed perpendicularly to the striking face from the front of the head,

[0072] the imaginary impact point 10 is a point on the striking face which is located on a vertical line 20 drawn on the striking face passing through the midpoint in the toe-heel direction between the most toe side end 7a and the most heel side end 7b of the face lines 7, and 18 mm above from the lower end 3e of the striking face 3.

[0073] Here, the use of the expression “the lower end 3e of the striking face 3” is however for convenience sake.

[0074] In reality, the reference position from which 18 mm is measured, is preferably the lowest position of the head in the front view when addressing the ball.

[0075] This position may not be on the flat striking face 3, but on the outer surface of a curved portion of the head connecting the striking face 3 and the sole 6.

[0076] However, for the sake of simplicity and clarity, the lower end 3e of the striking face 3 or the lower end of the vertical line 20 shown in FIG. 6 is used as the reference position.

[0077] As shown in FIG. 3, the top 5 extends from the upper edge of the striking face 3 toward the rear of the head and forms the upper surface of the head 1.

[0078] The sole 6 extends from the lower edge of the striking face 3 toward the rear of the head and forms the lower surface of the head 1.

[0079] The toe T is an end portion of the head 1 which is farthest from the hosel 9 in the toe-heel direction, and smoothly connects the top 5 and the sole 6.

[0080] The heel H is an end portion of the head 1 which is opposite the toe T in the toe-heel direction of the head and to which the hosel 9 is connected.<Thick Portion and Thin Portion>

[0081] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6.

[0082] This cross-section is at the position of the vertical line 20 as shown in FIG. 6 and is perpendicular to the striking face 3.

[0083] As shown, the face portion 2 comprises a thin portion 21 having a first thickness t1 and a thick portion 22 having a second thickness t2 larger than the first thickness t1.

[0084] In this application, the thickness of the face portion 2 (inclusive of the thickness t1 and the thickness t2) means a dimension measured in a direction perpendicular to the striking face 3, excluding the face lines 7.

[0085] The thin portion 21 is formed within the range of an imaginary circle R10 of 10.0 mm radius centered on the imaginary impact point 10 in the vertical state of the head 1 as shown in FIG. 6.

[0086] Incidentally, “within the range” means that the thin portion 21 does not protrude from the imaginary circle R10 centered on the imaginary impact point 10.

[0087] The thin portion 21 is defined as having a first thickness t1 in a range from 2.0 to 4.0 mm.

[0088] The thick portion 22 surrounds the thin portion 21, and forms, on the outside of the thin portion 21, at least the range of an imaginary circle R15 of 15 mm radius centered on the imaginary impact point 10.

[0089] The thick portion 22 is defined as having a second thickness t2 which is at least 4.0 mm and larger than the first thickness t1 by at least 1.0 mm.

[0090] It is effective for preventing the deterioration in the hit feel of the club head to provide a thick portion 22 near the imaginary impact point 10 of the striking face 3, but such a club head tends to have a small right-left MOI, leading to poor forgiveness on mishits, and there is a problem such that the flight direction of the ball deviates.

[0091] The inventor studied to solve this problem, focusing on the relationship between the area where the thin portion 21 is formed and the contact area between the ball and the striking face 3 occurring when the ball is struck. And so this disclosure was made.

[0092] FIG. 8 shows an example of the contact area (A) between a ball and the striking face when the ball having a standard compressive deformation amount of approximately 2.2 to 3.0 mm was struck.

[0093] The compressive deformation amount was measured using a YAMADA compression tester “SCH.” In the measurement, a golf ball is placed on a rigid metal plate.

[0094] Then, a rigid metal cylinder gradually descends toward the golf ball, and the golf ball between the cylinder and the rigid metal plate is deformed.

[0095] The compressive deformation amount (mm) is determined by the moving distance of the cylinder from when an initial load of 98 N is applied to the golf ball to when a final load of 1275 N is applied.

[0096] The moving speed of the cylinder is set to 0.83 mm / s until the initial load is applied. From the application of the initial load to the application of the final load, the moving speed of the cylinder is set to 1.67 mm / s.

[0097] The contact area (A) was obtained by striking the golf ball with the striking face to which a pressure-sensitive sheet S was attached in advance.

[0098] As a result of many hitting tests by professionals and advanced golfers, it was found that the contact areas (A) have approximately circular contour shapes with diameters D in the range from 21 to 23 mm.

[0099] Further, the inventor found after further experiments, that by forming a thin portion 21 which is smaller than the contact area (A), in the vicinity of the imaginary impact point 10, and also forming a thick portion 22 on the outside of thin portion 21, it is possible to reduce the weight near the imaginary impact point 10 and increase the right-left MOI, while preventing the deterioration in the fit feel.

[0100] That is, by forming the thin portion 21 within the range of the imaginary circle R10, and by forming the thick portion 22 outside the thin portion 21 so as to surround the thin portion 21 and extend to at least the range of the imaginary circle R15,

[0101] a large right-left MOI can be provided, while preventing the deterioration in the hit feel. Such a large right-left MOI can minimize the change in the orientation of the face portion 2 on mishit, thereby improving the forgiveness on mishits (reducing the deviation of the flight direction of the struck ball).

[0102] The head 1 in the present embodiment, with the above-described structure, may have a large right-left MOI of not less than 2200 g sq. cm, preferably not less than 2250 g sq. cm, more preferably not less than 2300 g sq. cm.

[0103] The first thickness t1 of the thin portion 21 is set in the range of 2.0 to 4.0 mm.

[0104] By setting the first thickness t1 to at most 4.0 mm, the weight can be effectively reduced from the vicinity of the imaginary impact point 10.

[0105] From the viewpoint of increasing the right-left MOI, the first thickness t1 is preferably 3.5 mm or less, more preferably 3.0 mm or less.

[0106] By setting the first thickness t1 to 2.0 mm or more, the strength and durability required for the face portion 2 are sufficiently secured.

[0107] As the thin portion 21 is formed within the range of the imaginary circle R10 of 10.0 mm radius centered on the imaginary impact point 10,

[0108] at least a portion of the contact area (A) (D=21 to 23 mm) can include the thick portion 22. This is useful for the head 1 in the present embodiment to provide a good, solid hit feel with less vibration.

[0109] It is not particularly limited as long as the thin portion 21 is formed within the above range, but, preferably it may be formed within the range of an imaginary circle of 9.0 mm radius centered on the imaginary impact point 10, more preferably it may be formed within the range of an imaginary circle of 8.0 mm radius centered on the imaginary impact point 10.

[0110] In order to further improve the hit feel and increase the effect of increasing the right-left MOI of the head 1, it is preferable that the thin portion 21 forms at least the entire range of an imaginary circle of 2.5 mm radius centered on the imaginary impact point 10. Further, the thin portion 21 may form the entire range of an imaginary circle of 4.0 mm radius centered on the imaginary impact point 10.

[0111] Furthermore, the thin portion 21 may form the entire range of an imaginary circle of 5.0 mm radius centered on the imaginary impact point 10.

[0112] The formation range of the thin portion 21 may be determined by the projected area of the thin portion 21 projected onto the striking face 3.

[0113] The projected area of the thin portion 21 may be 314 sq. mm or less, preferably 300 sq. mm or less.

[0114] The projected area of the thin portion 21 may be 20 sq. mm or more (when the thin portion is circular, the radius r is approximately 2.5 mm or more), preferably 50 sq. mm or more (when the thin portion is circular, the radius r is approximately 4 mm or more).

[0115] In order to provide a good hit feel, it is necessary that at least a part of the thick portion 22 is included in the contact area (A) between the ball and the striking face 3.

[0116] In the head 1 in the present embodiment, as the thick portion 22 surrounds the thin portion 21 and forms at least the range of the imaginary circle R15 of 15 mm radius centered on the imaginary impact point 10,

[0117] such thick portion 22 can cover the contact area (A) even when the actual hitting point is slightly deviated from the imaginary impact point 10.

[0118] As a modified example, the thick portion 22 may form at least the range of an imaginary circle of 20 mm radius centered on the imaginary impact point 10.

[0119] The second thickness t2 of the thick portion 22 is not particularly limited as long as it is 4.0 mm or more and is at least 1.0 mm larger than the first thickness t1.

[0120] But, preferably, the second thickness t2 may be 4.5 mm or more, more preferably 5.0 mm or more.

[0121] Preferably, the second thickness t2 may be at least 1.5 mm larger than the first thickness t1, and further may be at least 2.0 mm larger than the first thickness t1.

[0122] When the difference t2−t1 in thickness is increased in this way, the hit feel and the right-left MOI are improved in a more balanced manner.

[0123] As shown in FIGS. 2, 4 and 7, the face portion 2 of the present embodiment includes an upper blade portion 100 extending downward from the top 5, and a lower protruding portion 200 protruding rearward of the head from the upper blade portion 100 on the sole 6 side thereof.<Upper Blade Portion>

[0124] The upper blade portion 100 may be formed with a constant thickness.

[0125] But, in the present embodiment, the upper blade portion 100 has a variable thickness. The upper blade portion 100 in the present embodiment includes a top side frame portion 101, a toe side frame portion 102, a heel side frame portion 103, a toe side recessed portion 104, a heel side recessed portion 105, and a central protruding portion 106.

[0126] The top side frame portion 101 extends in the toe-heel direction, including the top 5.

[0127] The toe side frame portion 102 is connected to the toe T side of the top side frame portion 101 and extends downward.

[0128] The heel side frame portion 103 is connected to the heel H side of the top side frame portion 101 and extends downward.

[0129] The frame portions 101, 102 and 103 constitute a peripheral portion of the upper blade portion 100, and has a relatively large thickness.

[0130] Preferably, each of the frame portions 101, 102 and 103 has a thickness of 4.0 mm or more, more preferably 5.0 mm or more, still more preferably 6.0 mm or more, and constitutes the above-described thick portion 22.

[0131] Further, each of the frame portions 101, 102 and 103 preferably has a width W of 4.0 mm or more, more preferably 5.0 mm or more. Here, the width W is the dimension measured in a direction perpendicular to the longitudinal direction of the frame portion, for example, as shown in FIG. 2.

[0132] The toe side recessed portion 104 and the heel side recessed portion 105 are surrounded by the frame portions 101, 102 and 103, and are located on the toe T side and heel H side, respectively.

[0133] The toe side recessed portion 104 and the heel side recessed portion 105 each have a relatively small thickness as compared to each of the frame portions 101, 102 and 103. In the present embodiment, each of the toe side recessed portion 104 and the heel side recessed portion 105 has a thickness of 3.0 mm or less, for example.

[0134] The central protruding portion 106 of the present embodiment is formed between the toe side recessed portion 104 and the heel side recessed portion 105, and protrudes rearward of the head from the toe side recessed portion 104 and the heel side recessed portion 105.

[0135] The central protruding portion 106 of the present embodiment extends vertically so as to connect the top side frame portion 101 and the lower protruding portion 200.

[0136] Further, the central protruding portion 106 is formed so as to include the above-mentioned imaginary impact point 10 and imaginary circle R15.

[0137] Thus, the central protruding portion 106 forms the thick portion 22.

[0138] In the upper blade portion 100 configured as described above, due to the toe side recessed portion 104 and the heel side recessed portion 105 which are relatively thin thus relatively light weight, a weight margin which is usable at will can be created.

[0139] For example, such weight margin can be used to add weight to the frame portions, particularly the toe side frame portion 102 and the heel side frame portion 103 so that the right-left MOI of the head 1 is increased.

[0140] The lower protruding portion 200 extends in the toe-heel direction, including the sole 6. The lower protruding portion 200 is, on its toe T side, connected to the lower end of the toe side frame portion 102, and on its heel H side, connected to the lower end of the heel side frame portion 103.

[0141] The lower protruding portion 200 has the largest thickness in the face portion 2.

[0142] It is preferable that the lower protruding portion 200 at least partially includes a part having a thickness of 14.0 mm or more, more preferably 15.0 mm or more.

[0143] Such lower protruding portion 200 helps to increase the right-left MOI and lower the position of the center of gravity of the head.

[0144] As shown in FIG. 7, the back face 4 of the face portion is provided with a recess 11 in the area corresponding to the thin portion 21.

[0145] The recess 11 is recessed toward the striking face 3 and extends into both the upper blade portion 100 and the lower protruding portion 200.

[0146] That is, as shown in FIG. 7, portions on the upper side and lower sides of the recess 11 are both formed as the thick portion 22. Such head 1 may be further improved in the hit feel.

[0147] In the present embodiment, the projected area of the thin portion 21 projected onto the striking face 3 has a circular outline shape as indicated in FIG. 6 by dashed line, and the entire portion which is surrounded by the imaginary circle R10 (chain line) and continuously surrounds the thin portion 21 is formed as the thick portion 22.

[0148] Such thin portion 21 allows the annularly-continuous thick portion 22 to be positioned around the periphery of the contact area between the ball and the striking face 3 when the ball is struck. Thus it is useful for providing a better hit feel.

[0149] As other examples of the outline shape of the projected area of the thin portion 21 may be elliptical, or may be polygonal.

[0150] FIG. 9 shows an example where the outline shape is trapezoidal.

[0151] In this case, preferable is a trapezoidal shape in which the lower base is shorter than the upper base.

[0152] Such thin portion 21 reduces a larger amount of weight from the upper part of the face portion 2, and therefore, it is possible to lower the position of the center of gravity of the head 1 while achieving a larger right-left MOI.

[0153] 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

[0154] Iron-type golf club heads were experimentally manufactured as Examples Ex.1-Ex.5 and Comparable examples Ref.1-Ref.2, based on the structure shown in FIGS. 1 to 7, while slight changing the specifications as shown in Table 1. Then, the heads were tested for the hit feel and the right-left MOI.

[0155] In the head of Comparative Example Ref.1, the thin portion was omitted.

[0156] In each head of Examples Ex.1-Ex.5 and Comparative Example Ref.2, the thin portion was formed by drilling a circular recess on the back face of the head.

[0157] The center of the circular recess was at the imaginary impact point.

[0158] The radii of the circular recesses are shown in Table 1.

[0159] In order to make all of the heads the same weight, in the heads provided with the thin portion, the weight reduced by the formation of the thin portion was added evenly to a toe side portion and a heel side portion of the back face.

[0160] The hit feel was evaluated through a hitting test.

[0161] In the hitting test, the above-described iron-type golf club heads were attached to identical club shafts and iron clubs were prepared.

[0162] Each of 10 advanced golfers struck a golf ball six times using each of the iron clubs. Then, each golfer evaluated the hit feel of the iron clubs by his / her own senses based on Example Ex.1 being 100, wherein the larger the value, the better the hit feel.

[0163] For each of the iron clubs, the evaluation results by the 10 golfers were averaged and indicated in Table 1.

[0164] For the right-left MOI, a moment of inertia of each of the iron clubs around a vertical axis passing through the center of gravity of the head was measured. The results are indicated in Table 1.

[0165] The forgiveness on mishits was evaluated through the hitting test.

[0166] As described above, in the hitting test, the iron-type golf club heads were attached to the identical club shafts and the iron clubs were prepared.

[0167] Each of the 10 advanced golfers struck a golf ball six times using each of the iron clubs. Then, the each golfer evaluated deviations of the ball's trajectory and landing position on mishit as the forgiveness of the clubs by his / her own senses based on Example Ex.1 being 100, wherein the larger the value, the better the forgiveness. For each of the iron clubs, the evaluation results by the 10 golfers were averaged, and the averaged values for the respective heads are indicated in Table 1.TABLE 1Ref.Ref.Ex.Ex.Ex.Ex.Ex.1212345Club headHead weight (g)265265265265265265265Thin portionRadius (mm) *1—1110852.551st thickness—333333t1(mm)2nd thickness5555554t2(mm) *2t2 − t1 (mm)—222221Right-left2150240023502300225022002300MOI (g sq)Hit feel12080100105110115105Forgiveness7410610094878194*1 Thin portion was circular and centered on imaginary impact point*2 Thickness within imaginary circle R10 range

[0168] From the test results, it was confirmed that the golf club heads of Example Ex.1 to Ex.4 had larger right-left MOI and improved forgiveness while keeping the deterioration of the hit feel to 20 points or less as compared to Comparative Example Ref.1.

[0169] Further, it was confirmed that, in Comparative Example Ref.2, although the right-left MOI became large, the hit feel was 40 points lower than that in Comparative Example Ref.1, and the hit feel was significantly deteriorated.STATEMENT OF THE PRESENT DISCLOSURE

[0170] The present disclosure is as follows.Present Disclosure 1

[0171] An iron-type golf club head comprising:

[0172] a face portion comprising a striking face for striking a ball, and an imaginary impact point set on the striking face,

[0173] the striking face being provided with face lines extending in a toe-heel direction of the head, and

[0174] in a vertical state of the head in which the striking face is vertical and the face lines are horizontal, the imaginary impact point is defined as a point which is positioned on a vertical line passing through the midpoint in the toe-heel direction between a toe side end and a heel side end of the face lines, and which is located 18 mm above from a lower end of the striking face,

[0175] wherein

[0176] the face portion includes a thin portion having a first thickness, and a thick portion having a second thickness larger than the first thickness,

[0177] the first thickness is in a range from 2.0 to 4.0 mm,

[0178] the second thickness is not less than 4.0 mm and larger than the first thickness by at least 1.0 mm,

[0179] the thin portion is formed within a range of an imaginary circle of 10.0 mm radius centered on the imaginary impact point, and

[0180] the thick portion surrounds the thin portion on the outside thereof and forms at least a range of an imaginary circle of 15 mm radius centered on the imaginary impact point.Present Disclosure 2

[0181] The golf club head according to Present Disclosure 1, wherein the first thickness is not more than 3.0 mm.Present Disclosure 3

[0182] The golf club head according to Present Disclosure 1 or 2, wherein the second thickness is larger than the first thickness by at least 2.0 mm.Present Disclosure 4

[0183] The golf club head according to Present Disclosure 1, 2 or 3, wherein the thick portion forms at least a range of an imaginary circle having a radius of 20 mm and centered on the imaginary impact point.Present Disclosure 5

[0184] The golf club head according to any one of Present Disclosures 1 to 4, wherein the thin portion is formed within a range of an imaginary circle having a radius of 8.0 mm and centered on the imaginary impact point.Present Disclosure 6

[0185] The golf club head according to any one of Present Disclosures 1 to 5, wherein the thin portion forms at least a range of an imaginary circle having a radius of 2.5 mm and centered on the imaginary impact point.Present Disclosure 7

[0186] The golf club head according to any one of Present Disclosures 1 to 6, wherein a projected area of the thin portion projected onto the striking face is 20 to 314 sq. mm.Present Disclosure 8

[0187] The golf club head according to Present Disclosure 7, wherein an outline shape of the projected area is circular.Present Disclosure 9

[0188] The golf club head according to Present Disclosure 7, wherein an outline shape of the projected area is polygonal.Present Disclosure 10

[0189] The golf club head according to any one of Present Disclosures 1 to 9, wherein the face portion comprises a back face opposite to the striking face, a top, a sole, an upper blade portion extending downward from the top, and a lower protruding portion protruding rearward of the head from the upper blade portion on a sole side thereof, in a cross section of the face portion taken perpendicularly to the striking face and passing through the vertical line, the back face is provided with a recess in a position corresponding to the thin portion, and the recess is recessed toward the striking face and extends into both the upper blade portion and the lower protruding portion.DESCRIPTION OF THE REFERENCE SIGNS1 golf club head

[0191] 2 face portion

[0192] 3 striking face

[0193] 4 back face

[0194] 5 top

[0195] 6 sole

[0196] 7 face line

[0197] 10 imaginary impact point

[0198] 11 recess

[0199] 21 thin portion

[0200] 22 thick portion

[0201] R10 imaginary circle

[0202] R15 imaginary circle

[0203] t1 first thickness

[0204] t2 second thickness

Claims

1. An iron-type golf club head comprising:a face portion comprising a striking face for striking a ball, and an imaginary impact point set on the striking face,the striking face being provided with face lines extending in a toe-heel direction of the head, andin a vertical state of the head in which the striking face is vertical and the face lines are horizontal, the imaginary impact point is defined as a point which is positioned on a vertical line passing through the midpoint in the toe-heel direction between a toe side end and a heel side end of the face lines, and which is located 18 mm above from a lower end of the striking face,whereinthe face portion includes a thin portion having a first thickness, and a thick portion having a second thickness larger than the first thickness,the first thickness is in a range from 2.0 to 4.0 mm,the second thickness is not less than 4.0 mm and larger than the first thickness by at least 1.0 mm,the thin portion is formed within a range of an imaginary circle of 10.0 mm radius centered on the imaginary impact point, andthe thick portion surrounds the thin portion on the outside thereof and forms at least a range of an imaginary circle of 15 mm radius centered on the imaginary impact point.

2. The golf club head according to claim 1, whereinthe first thickness is not more than 3.0 mm.

3. The golf club head according to claim 1, whereinthe second thickness is larger than the first thickness by at least 2.0 mm.

4. The golf club head according to claim 2, whereinthe second thickness is larger than the first thickness by at least 2.0 mm.

5. The golf club head according to claim 1, whereinthe thick portion forms at least a range of an imaginary circle having a radius of 20 mm and centered on the imaginary impact point.

6. The golf club head according to claim 2, whereinthe thick portion forms at least a range of an imaginary circle having a radius of 20 mm and centered on the imaginary impact point.

7. The golf club head according to claim 3, whereinthe thick portion forms at least a range of an imaginary circle having a radius of 20 mm and centered on the imaginary impact point.

8. The golf club head according to claim 1, whereinthe thin portion is formed within a range of an imaginary circle having a radius of 8.0 mm and centered on the imaginary impact point.

9. The golf club head according to claim 2, whereinthe thin portion is formed within a range of an imaginary circle having a radius of 8.0 mm and centered on the imaginary impact point.

10. The golf club head according to claim 3, whereinthe thin portion is formed within a range of an imaginary circle having a radius of 8.0 mm and centered on the imaginary impact point.

11. The golf club head according to claim 4, whereinthe thin portion is formed within a range of an imaginary circle having a radius of 8.0 mm and centered on the imaginary impact point.

12. The golf club head according to claim 1, whereinthe thin portion forms at least a range of an imaginary circle having a radius of 2.5 mm and centered on the imaginary impact point.

13. The golf club head according to claim 2, whereinthe thin portion forms at least a range of an imaginary circle having a radius of 2.5 mm and centered on the imaginary impact point.

14. The golf club head according to claim 3, whereinthe thin portion forms at least a range of an imaginary circle having a radius of 2.5 mm and centered on the imaginary impact point.

15. The golf club head according to claim 5, whereinthe thin portion forms at least a range of an imaginary circle having a radius of 2.5 mm and centered on the imaginary impact point.

16. The golf club head according to claim 8, whereinthe thin portion forms at least a range of an imaginary circle having a radius of 2.5 mm and centered on the imaginary impact point.

17. The golf club head according to claim 1, whereina projected area of the thin portion projected onto the striking face is 20 to 314 sq. mm.

18. The golf club head according to claim 17, wherein.an outline shape of the projected area is circular.

19. The golf club head according to claim 17, whereinan outline shape of the projected area is polygonal.

20. The golf club head according to claim 1, whereinthe face portion comprises a back face opposite to the striking face, a top, a sole, an upper blade portion extending downward from the top, and a lower protruding portion protruding rearward of the head from the upper blade portion on a sole side thereof,in a cross section of the face portion taken perpendicularly to the striking face and passing through the vertical line, the back face is provided with a recess in a position corresponding to the thin portion, andthe recess is recessed toward the striking face and extends into both the upper blade portion and the lower protruding portion.

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