JP4996560B2 - Iron type golf club head - Google Patents

Description

  The present invention relates to an iron type golf club head having an improved weight distribution design while improving the feel at impact.

  In recent years, various iron-type golf club heads have been proposed in which a weight member having a large specific gravity is fixed to an appropriate position of the head body to increase the moment of inertia and improve the position of the center of gravity of the head.

  On the other hand, in an iron type golf club, since vibration transmitted to the golfer's hand at the time of a miss shot is larger than that in a wood type club, it is desired to have excellent vibration absorption performance.

  Conventionally, in order to improve vibration absorption performance, a technique has been proposed in which a vibration absorbing material such as resin or rubber is disposed inside an iron type golf club head (see Patent Document 1 below).

JP 2004-89434 A

  By the way, in order to sufficiently improve the vibration absorbing performance, it is necessary to use a vibration absorbing material having a relatively large volume. However, such a large volume vibration absorbing material has a problem in that the moment of inertia and the center of gravity of the head cannot be sufficiently improved because the degree of freedom of the location and position for disposing the weight member is impaired.

  The present invention has been devised in view of the above circumstances, and the weight member is arranged in a recess made of a through hole provided in the head body, and the opening of the recess is welded to the weight member. The main object is to provide an iron-type golf club head capable of further improving the degree of freedom in weight distribution design by providing a weight member with a vibration absorbing effect and a weight effect on the basis of providing non-vibrating non-welded portions. It is said.

  According to the first aspect of the present invention, a head main body having a face for hitting a ball and made of a metal material, and a weight member made of a metal material fixed to the head main body and having a larger specific gravity than the head main body. A concave portion for attaching a weight member to the head body, and the concave portion has a first opening that opens on one surface of the head outer surface, and the one The second surface, which is different from the first surface, is formed of a through hole communicating with the second opening spaced apart from the first opening inside the head, and the weight member includes at least the first opening and the first opening. And a welded portion welded to the first opening and a non-welded portion not welded to the second opening.

  The invention according to claim 2 is the iron type golf club head according to claim 1, wherein the depth L1 of the non-welded portion is larger than the weld depth L2 of the welded portion.

  The invention according to claim 3 is the iron type golf club head according to claim 2, wherein the ratio (L1 / L2) is 1.5 to 10.0.

  According to a fourth aspect of the present invention, the head body includes a face portion whose front surface forms the face, a sole wall portion extending from the lower end portion of the face portion to the rear of the head, and an upper portion from the rear end portion of the sole wall portion. And a back wall portion that forms an undercut cavity with the back surface of the face portion, and at least part of the first opening extends on the back surface side of the back wall portion, and 4. The iron type golf club head according to claim 1, wherein at least a part of the opening of 2 extends on a front surface side of the back wall portion.

  According to a fifth aspect of the present invention, there is one first opening, and the second opening passes through the center of gravity of the head in a reference state placed on a horizontal plane at a specified lie angle and loft angle. 5. The iron type golf club head according to claim 4, comprising a toe side opening and a heel side opening provided on both sides of a vertical surface perpendicular to the face.

  In the iron type golf club head of the present invention, a concave portion for attaching a weight member is provided in the head main body, and the concave portion is different from the first surface opened on one surface of the head outer surface and the one surface. A second opening that is spaced apart from the first opening on the other surface is a through hole that communicates within the head. The weight member extends at least between the first opening and the second opening, and includes a welded portion welded to the first opening and a non-welded portion not welded to the second opening. Have.

  The opening of the concave portion of the head body and the non-welded portion of the weight member that is not welded freely vibrate by the impact energy at the time of hitting the ball, and the vibration energy of the head is quickly attenuated. Accordingly, vibration transmitted to the golfer's hand is reduced. Thus, the club head of the present invention can exhibit vibration absorbing performance using the weight member without separately providing a vibration absorbing material made of conventional rubber or the like. Accordingly, it is possible to freely set the placement location and placement position of the weight member, and to increase the degree of freedom of weight distribution design.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a reference state of an iron type golf club head (hereinafter, simply referred to as “head” or “club head”) 1 of the present embodiment, FIG. 2 is a rear view thereof, and FIGS. FIG. 3 is an enlarged end view taken along lines XX, YY and ZZ in FIG. 2, respectively.

  Here, the reference state of the club head 1 is a state in which the head 1 is held at its lie angle α and loft angle β (shown in FIG. 4) and is grounded to the horizontal plane HP. Unless otherwise stated, it is assumed that the club head 1 is placed in this reference state.

  The club head 1 includes a face 2 for hitting a ball, a top surface 3 connected to the upper edge of the face 2 and forming the upper portion of the head 2, and a sole surface 4 connected to the lower edge of the face 2 and forming the head bottom surface. A toe surface 5 that smoothly curves and joins between the top surface 3 and the sole surface 4, a back face surface 6 that forms a surface opposite to the face 2, and a shaft plug on which a shaft (not shown) is mounted. And a hosel portion 7 having a hole 7a. When the club shaft is not mounted, the lie angle α of the head 1 can be based on the center line CL of the shaft insertion hole 7a.

  Further, as shown in FIGS. 2 to 5, the club head 1 of the present embodiment includes a head main body 1A having the face 2 and made of a metal material, and is fixed to the sole surface 4 side and is from the head main body 1A. And a weight member 1B made of a metal material having a large specific gravity.

  In the present embodiment, as shown in FIGS. 3 to 5, the head main body 1A is made of a plate-like face member 1A1 and a metal material different from the face member 1A1, and the face member 1A1 is mounted on the front surface. It is comprised from the receiving frame part 1A2. However, the head main body 1A may be integrally formed of a single material.

  As a preferred embodiment, a metal material having a specific gravity smaller than that of the receiving frame portion 1A2 is used for the face member 1A1. For example, an aluminum alloy, a titanium alloy or a magnesium alloy is preferably used for the face member 1A1, while a stainless steel such as SUS630, SUS304 or SUS410, a carbon steel such as S20C or S25C, or Fe— is used for the receiving frame portion 1A2. A steel material based on Fe, such as a Mn-Al alloy, is preferably used. As a result, a large weight is distributed to the peripheral portion of the face 2, and as a result, the head 1 is provided that is excellent in the direction of hitting with a large moment of inertia and a sweet area.

  In the present embodiment, the face member 1A1 is formed in a plate shape having a substantially constant thickness t except for impact area marking such as the face line FL. However, the thickness of the face member 1A1 may be decreased stepwise or continuously toward the center of the face member 1A1, or may be increased. Further, it is preferable that the contour shape of the face member 1A1 gradually increases in height from the heel side to the toe side in accordance with the contour of the face 2, for example. Accordingly, a wider range of the face 2 can be configured with the low specific gravity face member 1A1.

  The thickness t of the face member 1A1 is not particularly limited, but if it is too small, the durability tends to deteriorate, whereas if it is too large, the resilience performance of the head 1 tends to decrease. For this reason, the thickness t is preferably 1.5 mm or more, more preferably 1.8 mm or more, and further preferably 2.0 mm or more. The upper limit is preferably 4.0 mm or less, more preferably 3. 5 mm or less, more preferably 3.0 mm or less is desirable.

  As shown in FIGS. 6 and 7, the receiving frame portion 1 </ b> A <b> 2 is connected to an outer peripheral frame 9 provided with a face mounting portion 8 to which the face member 1 </ b> A <b> 1 is attached, and the outer peripheral frame 9 via a neck portion 10. The hosel portion 7 is provided.

  The outer peripheral frame 9 connects a top portion frame 9a extending from the toe side to the heel side obliquely downward, a head bottom portion toe, a sole portion frame 9b extending in the heel direction, and a toe side. The toe part frame 9c and the top part frame 9a, the toe part frame 9c, the sole part frame 9b, and the through-hole part O penetrating in the head front-rear direction are surrounded by the inner edges of the neck part 10.

  As shown in FIG. 7, the face attachment portion 8 is provided around the through-hole portion O. The face mounting portion 8 has an annular receiving surface 8A that supports the peripheral portion of the back surface 11 of the face member 1A1, and an inner periphery that extends forward from the outer peripheral edge of the receiving surface 8A and can hold the outer peripheral surface 12 of the face member 1A1. It is formed in a substantially step shape including the surface 8B. Then, the face member 1A1 is mounted on the face mounting portion 8 of the receiving frame portion 1A2, and, for example, the head member 1A1 is plastically deformed and caulked so as to hold the face member 1A1, thereby integrating the two members together. Can stick. For fixing both members, various methods such as welding, brazing or adhesive can be adopted in addition to caulking.

  As shown in FIG. 4, the sole frame 9b includes a sole wall portion 16 extending from the lower end portion of the face portion F having the face 2 on the front surface to the rear of the head, and a rear end portion of the sole wall portion 16. It includes a back wall portion 17 that forms an undercut cavity C between the face portion F and the back surface of the face portion F by rising upward. Such a cavity structure helps to position the head center of gravity G further rearward.

  In the present embodiment, the weight member mounting recess 13 that is recessed from the outer surface of the head is provided on the bottom side of the head body 1A. The head outer surface means the outer surface of the completed club head.

  The concave portion 13 of the present embodiment includes a first opening e1 that opens on one surface E1, and a second opening e2 that is separated from the first opening e1 on the other surface E2 that is different from the one surface E1. The first and second openings e1 and e2 are formed with through holes having a space i that allows communication between the first and second openings e1 and e2. Specifically, in the recess 13 of the present embodiment, one surface E1 includes the back surface of the back wall portion 17 and the sole surface 4, and the other surface E2 is the front surface of the back wall portion 17.

  As shown in FIGS. 3 and 6, the first opening e <b> 1 includes, for example, an upper opening edge e <b> 1 a extending over the back wall portion 17 and a lower opening edge e <b> 1 b extending over the sole surface 4. In addition, the first opening e1 is formed in a substantially arcuate shape that extends in a horizontally elongated manner on the toe side and the heel side, and has both end portions smoothly curved upward.

  On the other hand, as shown in FIGS. 6 and 7, the second opening e2 has a toe side opening e2t provided on both sides of a vertical plane VP2 that passes through the center of gravity G of the head and is perpendicular to the face 2 in the reference state. And a heel side opening e2h.

  As shown in FIGS. 3 and 4, the void i includes a first concave surface 15 a composed of a single plane substantially parallel to the face 2 from the lower opening edge e 1 b, and the upper opening edge e 1 a to the face 2. And a second concave surface 15b extending substantially at right angles, and a toe side hole portion 15ct and a heel side hole portion 15ch extending rearward from the second openings e2t and e2h.

  Moreover, the recessed part 13 of this embodiment is provided in the position lower than the sweet spot SS, as FIG.4 and FIG.6 shows. This makes it possible to attach the weight member 1B to a lower position of the head main body 1A, which helps to lower the center of gravity. Note that the sweet spot SS is an intersection of the normal N and the face 2 standing on the face 2 from the center of gravity G of the head, as shown in FIG.

  As shown in FIG. 8, the weight member 1 </ b> B of the present embodiment substantially matches the shape of the space i of the recess 13. Specifically, the weight member 1B is formed in a substantially arch shape that extends in a horizontally long shape in the toe and heel directions and has both ends smoothly curved upward. More specifically, the weight member 1B of the present embodiment connects the toe side convex portion 18 extending in the toe side hole portion 15ct and the heel side convex portion 19 extending in the heel side opening portion 15ch. And it is comprised from the connection part 20 which faces the 1st concave surface 15a and the 2nd concave surface 15b. The connecting portion 20 includes a first surface 20a facing the first concave surface 15a of the concave portion 13, a second surface 20b facing the second concave surface 15b, and a third surface 20c exposed to the head outer surface.

  The weight member 1B as described above is attached to the recess 13 from the first opening e1 side. Thereby, the weight member 1B extends between the first opening e1 and the second opening e2, and substantially fills the void i. FIG. 9 shows a state in which the weight member 1B is fitted into the receiving frame portion 1A2.

  Thereby, the toe side convex part 18 and the heel side convex part 19 of the weight member 1B are fitted into the toe side hole part 15ct and the heel side hole part 15h, respectively. Further, the connecting portion 20 of the weight member 1B is disposed such that the first surface 20a and the second surface 20b substantially contact the first concave surface 15a and the second concave surface 15b, respectively. Further, the third surface 20c of the weight member 1B constitutes a part of the sole surface 4 and a part of the back surface (head outer surface) of the back wall portion 6, and also through the first opening e1 and a small gap. It is a series.

  Further, in the present embodiment, the toe side convex portion 18 and the heel side convex portion 19 both protrude from the respective openings e2 to the face 2 side as shown in FIGS. Has a length that does not contact. That is, a gap is provided between the back surface of the face portion F and the convex portions 18 and 19. The gap is formed in such a size that it does not come into contact with the face portion F even when the ball is hit. As a result, free deflection of the face portion F at the time of hitting the ball is ensured, and a decrease in flight distance can be prevented.

  The weight member 1B is made of a metal material having a specific gravity greater than that of the head body 1A. In the case of this embodiment, the weight member 1B is made of a metal material having a specific gravity larger than that of the face member 1A1 and the receiving frame portion 1A2. By fixing the weight member 1B made of such a high specific gravity material to the head main body 1A, the center of gravity of the head 1 can be adjusted to a desired position.

  The weight member 1B of this embodiment is useful for distributing the center of gravity G of the head more widely in the rear and lower places by extending horizontally in the toe-heel direction. Further, since the weight member 1B has convex portions 18 and 19 that are longer in the front-rear direction than the connecting portion 20 on the toe side and the heel side, more weight is distributed to both sides of the face toe and heel. it can. This helps increase the moment of inertia of the club head 1 and stabilize the directionality of the hit ball.

  The weight member 1B is formed of a metal material that can be welded to the receiving frame portion 1A2. Such a metal material is not particularly limited because it is determined depending on the combination with the receiving frame portion 1A2. As an example, when the receiving frame portion 1A2 is made of a steel material such as stainless steel or soft iron, the weight member 1B is preferably a tungsten alloy, particularly a W—Fe—Ni alloy in which iron and nickel are mixed in tungsten.

  The tungsten alloy preferably contains 15 to 50 wt% W, 12 to 30 wt% Fe, and 30 to 69 wt% Ni. When W is less than 15 wt%, the specific gravity cannot be increased. Conversely, when W exceeds 50 wt%, the hot water flow becomes worse, and thus, for example, moldability by casting may be deteriorated. If Fe is less than 12 wt%, welding to the steel receiving frame 1A2 may be difficult. Conversely, if it exceeds 30 wt%, the rust prevention property may be reduced. Furthermore, if Ni is less than 30 wt%, the corrosion resistance may be reduced. Conversely, if Ni is more than 69 wt%, the strength may be reduced and the specific gravity may be reduced.

  In order to effectively adjust the position of the center of gravity G of the head, the specific gravity of the weight member 1B is preferably 8.5 or more, more preferably 9.0 or more. On the other hand, if the specific gravity of the weight member 1B is too large, the material cost may increase. Therefore, it is preferably 13.0 or less, more preferably 12.5 or less. Note that the weight member 1B can be manufactured by various methods such as casting, forging, cutting, or sintering, and a cast product capable of precision molding is particularly desirable.

  The weight of the weight member 1B is not particularly limited, but if it is too small, the center-of-gravity adjustment effect may not be sufficiently obtained. Conversely, if the weight member 1B is too heavy, it is used for the receiving frame 1A2. The possible weight is limited, and the club head 1 may be forced to be downsized. From such a viewpoint, the weight of the weight member 1B is preferably 30 g or more, more preferably 40 g or more, further preferably 45 g or more, and the upper limit is preferably 100 g or less, more preferably 90 g or less, still more preferably Is preferably 80 g or less.

  In the present embodiment, the weight member 1B and the concave portion 13 of the head main body 1A are fixed by welding, but the welding is performed only from one surface E1, and not from the other surface E2. Thus, the weight member 1B includes the welded portion 22 welded to the first opening e1 and the non-welded portion 23 that is not welded to the second opening e2.

  In this way, by providing the convex portions 18 and 19 of the weight member 1B with the non-welded portion 23 that is not welded to the head main body 1B and can freely vibrate, the impact energy at the time of hitting the ball is not welded to the weight member 1B. It is consumed quickly by concentrating on the part 23 and vibrating this part. Therefore, in the club head 1 of the present embodiment, the vibration of the head main body 1A at the time of hitting the ball is attenuated early, and the unpleasant vibration transmitted to the hand of the golfer is effectively suppressed. In particular, when the protruding length K of the weight member 1B that protrudes from the back wall portion 17 is 1.0 mm or more, the non-welded portion 23 is further vibrated freely and the vibration absorbing effect is exhibited.

  As shown in FIG. 4, the connecting portion 20 of the weight member 1 </ b> B also has a non-welded portion 23 that is not welded to the head main body 1 </ b> A on the back side of the recessed portion 13. However, as a result of various experiments conducted by the inventors, this portion is constrained by the first and second concave surfaces 15a and 15b, and substantial free vibration cannot be achieved. Therefore, such a non-welded portion 23 can hardly exhibit a vibration absorbing effect.

  In addition, as described above, the club head 1 of the present embodiment can achieve the vibration absorption effect by improving the arrangement or mounting structure of the weight member 1B. Therefore, it is not necessary to separately provide a vibration absorbing material made of conventional rubber, resin, or the like, and the arrangement space or arrangement position of the weight member 1B can be freely set. This helps to further improve the degree of freedom of weight distribution design.

  Here, as shown in FIG. 3, the depth L1 along the opening 14 of the non-welded portion 23 is not particularly limited, but if it is too small, the above-described vibration absorption effect may be reduced. is there. From such a viewpoint, the depth L1 of the non-welded portion 23 is preferably 3 mm or more, more preferably 5 mm or more, and further preferably 6 mm or more. In the present embodiment, the depth L1 is measured in a vertical cross section perpendicular to the face 2 and is an actual length measured along the surface of the recess 13 from the second opening e2. That is, when the inner surface of the recess 13 is straight, such as the upper surface of the recess 13 in FIG. The sum of the distances L1a and L1b measured together.

  Also, the welding depth L2 of the welded portion 22 is not particularly limited, but if it is too small, the bonding strength between the weight member 1B and the head main body 1A may be lowered. Is preferably 2 mm or more. Conversely, if the welding depth L2 of the welded portion 22 is too large, the depth L1 of the non-welded portion 23 becomes relatively small, and the above-described vibration absorption effect may be reduced. Preferably it is 5 mm or less, more preferably 4 mm or less.

  The numerical limitation regarding the depths L1 and L2 may be as long as the average value of the lengths measured at a plurality of locations is satisfied.

  Moreover, it is desirable that the depth L1 of the non-welded portion 23 is greater than the weld depth L2 of the welded portion 22. As a result, a vibration absorbing effect can be further exhibited.

  In particular, in order to improve the vibration absorption effect and the joint strength in a well-balanced manner, the ratio (L1 / L2) between the depth L1 of the non-welded portion 23 and the weld depth L2 of the welded portion 22 is preferably 1.5. More preferably, 2.0 or more is desirable, preferably 10.0 or less, more preferably 7.0 or less, and still more preferably 5.0 or less.

  Further, the weight member 1B of the present embodiment has a toe side convex portion 18 and a heel side convex portion 19 on both sides of the sweet spot SS, and a non-welded portion 23 is provided on each of them. For this reason, a large vibration at the time of a miss shot in which the ball is hit on the toe side or the heel side of the sweet spot SS of the face 2 is more effectively absorbed by the free vibrations of these convex portions 18 and 19. desirable.

  In the non-welded portion 23, it is desirable that a gap be provided between the concave portion 13 and the convex portions 18 and 19 of the weight member 1B. Thereby, the non-welded part 23 can be vibrated more effectively. However, if the gap is increased, the weight member 1B may be easily detached, or the volume of the weight member 1B may be reduced to reduce the weight adjustment effect. From such a point of view, the gap is larger than 0 mm, preferably 0.05 mm or more, preferably 0.5 mm or less, more preferably 0.3 mm or less, and further preferably 0.2 mm or less. Particularly preferably, the thickness is 0.1 mm or less.

  Of course, there may be a portion that partially exceeds the numerical range regarding the gap. However, the above numerical range is preferably satisfied in the range of at least 5 mm, more preferably the entire range of the non-welded portion 23 from the second opening e2 into the recess 13.

  On one surface E1 of the outer surface of the head, the weight member 1B and the recess 13 are welded to improve the appearance by eliminating the gap and to effectively intrude foreign substances from these interfaces. Can be prevented. In addition, a gap is generated between the weight member 1B and the recess 13 on the front surface of the back wall portion 17 that is the other surface E2. However, since this part is an undercut cavity, it is difficult to see from the outside. Therefore, there is no deterioration in aesthetics, and it is difficult for foreign matter to enter.

  The shapes of the weight member 1B and the recessed portion 13 are not limited to the above-described embodiments, and can be implemented by being modified into various shapes. For example, as shown in FIG. 10, the second opening e2 of the recess 13 may be one continuous in the toe-heel direction. 11A to 11C are enlarged end views corresponding to the lines XX, YY, and ZZ in FIG.

  As mentioned above, although embodiment of this invention was described, this invention can be implemented in a various aspect.

  Iron type golf club heads were prototyped based on the specifications in Table 1 and FIGS. In each example, a face member, a receiving frame portion, and a weight member were prepared separately. Then, the head body and the weight member were first fitted and temporarily assembled, and the boundary between the weight member and the first opening was welded by plasma welding on the back surface and the bottom surface of the head. Thereafter, only in the comparative example, as shown in FIG. 13, the boundary between the weight member and the second opening was welded on the front surface of the back wall portion. After that, the face member was fixed to the head body by caulking. The penetration depth of the weld is about 3 mm. Moreover, in the Example, the clearance gap between a convex part and an opening part was 0-0.3 mm.

In addition, common specifications other than those described in Table 1 are as follows.
Loft angle 24 degrees Material of receiving frame part: SUS630 casting Specific gravity of receiving frame part: 7.8
Face member material: Ti-6Al-4V press-molded product Face member specific gravity: 4.42
Material of weight member: cast tungsten alloy composition of tungsten alloy; W: 20 wt%, Fe: 15 wt%, Ni: 60 wt%, Cr: 3 wt% and the balance (C, Si, Mn, N, etc.)
Specific gravity of the weight member: 9.5
Total head weight: 249g

  Next, the center-of-gravity height GH (FIG. 4) and the left and right moments of inertia (the moment of inertia about the vertical axis passing through the head center of gravity) were measured for each club head. Further, an iron type golf club was manufactured by fixing a carbon shaft (MP400, Flex S) manufactured by SRI Sports Co. to each club head, and the shot feeling was tested.

  Twenty golfers with handicap 5 to 25 hit a commercially available three-piece golf ball with each test club, and the presence or absence of unpleasant vibration was evaluated by a five-point method based on the sensation of each golfer. The larger the value, the better the feel at impact.

  The test results are shown in Table 1. It was confirmed that the club head of the example had a low center of gravity and an excellent shot feeling.

1 is a front view of a club head in a reference state showing an embodiment of the present invention. FIG. FIG. 3 is an enlarged sectional view taken along line XX in FIG. 2. It is the YY line expanded sectional view of FIG. FIG. 3 is an enlarged sectional view taken along line ZZ in FIG. 2. It is a rear view of a receiving frame part. It is a perspective view of a receiving frame part. It is a perspective view of a weight member. It is a perspective view in the state where a weight member was attached to a receiving frame part. It is a perspective view of the receiving frame part which shows other embodiment. (A)-(c) is XX, YY, and ZZ sectional drawing of FIG. (A), (b) is sectional drawing explaining the dimension of the club head of an Example. (A), (b) is a fragmentary sectional view for demonstrating the dimension of the club head of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Golf club head 1A Head main body 1A1 Face member 1A2 Receiving frame part 1B Weight member 2 Face 3 Top surface 4 Sole surface 5 Toe surface 6 Back face surface 13 Concave part 18 Toe side convex part 19 Heel side convex part 20 Connection part 22 Welding part 23 Non-welded portion E1 One surface E2 The other surface e1 First opening e2 Second opening

Claims (5)

An iron type golf club head including a head body made of a metal material having a face for hitting a ball, and a weight member made of a metal material fixed to the head body and having a specific gravity larger than that of the head body,
The head main body is provided with a concave portion for attaching a weight member, and the concave portion has a first opening that opens on one surface of the head outer surface and the first surface on the other surface different from the one surface. A second opening that is spaced apart from the first opening and a second opening that communicates within the head, and the weight member extends at least between the first opening and the second opening, and the first opening An iron-type golf club head comprising: a welded portion welded to the first opening and a non-welded portion not welded to the second opening.   2. The iron type golf club head according to claim 1, wherein a depth L1 of the non-welded portion is larger than a weld depth L2 of the welded portion.   3. The iron type golf club head according to claim 2, wherein the ratio (L1 / L2) is 1.5 to 10.0. The head body has a face portion whose front face forms the face, a sole wall portion extending from the lower end portion of the face portion to the rear of the head, and rising upward from a rear end portion of the sole wall portion, thereby A back wall that forms an undercut cavity between the back and
The at least part of said 1st opening extends in the back side of the said back wall part, and at least one part of the said 2nd opening extends in the front side of the said back wall part. Iron type golf club head. The first opening is one, and the second opening is on both sides of a vertical plane passing through the center of gravity of the head and perpendicular to the face in a reference state placed on a horizontal plane at a specified lie angle and loft angle. 5. The iron-type golf club head according to claim 4, comprising a toe side opening and a heel side opening provided.

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