JP5525570B2 - Iron type golf club head - Google Patents

Description

  The present invention relates to an iron-type golf club head that can increase the flight distance while improving the feel at impact.

  As shown in FIG. 8 (a) and FIG. 8 (b) which is an AA cross-section thereof, the applicant of the present application forms an upper open undercut cavity e on the back surface c and sole surface d side of the face b. An iron type golf club head having a possible back wall portion f has been proposed (see, for example, Patent Document 1 below). Such a golf club head a can absorb impact energy at the time of hitting the ball by the back wall portion f, and thereby reduce vibration transmitted to the hand of the golfer, thereby improving the feel at impact.

JP 2004-305335 A

  The inventors have made extensive studies to further increase the flight distance while improving the feel at impact. As a result, the inventors have obtained the knowledge that it is effective to increase the average height of the back wall on the toe side and the heel side and lower on the intermediate part, and have completed the present invention.

  As described above, the main object of the present invention is to provide an iron-type golf club head capable of increasing the flight distance while improving the feel at impact on the basis of regulating the height of the back wall. It is said.

According to a first aspect of the present invention, there is provided an iron type golf club head having a top surface, a sole surface, a toe surface connecting between the top surface, and a face for hitting a ball, the back surface of the face A rear bulge that protrudes rearward from the head and extends in an annular shape is provided at the peripheral edge of the head, so that a cavity surrounded by the rear bulge is formed on the back of the face, and in the toe-heel direction along the sole surface The back bulge portion on the sole portion side that extends is provided with a back wall portion that rises upward from the rear end portion and terminates without reaching the rear bulge portion on the top portion side. And an undercut cavity that is formed below and sandwiched between the back wall and the back of the face. In the rear view of the head in the face vertical state where the loft angle is made to be zero from the reference state grounded to the horizontal plane at the loft angle, the most toe side position and the most heel side position of the open cavity portion When the horizontal length is virtually divided into three equal parts of the toe side region, the intermediate region and the heel side region, the average height Ht of the back wall portion of the toe side region, the average of the back wall portion of the intermediate region The height Hc and the average height Hh of the back wall portion in the heel side region satisfy the following formula, and when viewed from the back of the head, the back wall portion includes a toe side wall portion extending on the toe side and a heel side wall portion extending on the heel side. An intermediate wall portion extending between them and having a step in the toe side wall portion and the heel side wall portion and having a small height, and an upper edge of the toe side wall portion and an upper edge of the intermediate wall portion, Tilts down toward the heel side Is connected by a U side beveled edge, wherein the upper edge of the upper edge and the intermediate wall portion of the heel side wall, by being connected by the heel side oblique edge inclined in toe side downward, the head plane In view, the upper edge of the back wall portion is formed with the substantially trapezoidal step having a length gradually decreasing in the toe-heel direction at a substantially middle portion in the toe-heel direction. To do.
Ht> Hc and Hh> Hc

  According to a second aspect of the present invention, the average height Ht of the back wall portion of the toe side region is larger than the average height Hh of the back wall portion of the heel side region. It is.

  According to a third aspect of the present invention, the ratio of the average heights (Hc / Ht) and (Hc / Hh) is 0.30 to 0.95. The iron type golf club head according to the first or second aspect It is.

  In the iron type golf club head of the present invention, by providing a back wall portion that forms an undercut cavity portion on the back surface of the face, vibration at the time of hitting the ball is transmitted to the back wall portion through the rear raised portion and absorbed. Is done. This improves the feel at impact.

  Further, the average height of the back wall portion extending through the toe side region and the heel side region is formed larger than the average height of the back wall portion extending through the intermediate region. Therefore, even in the case of a miss shot in which the ball is hit on the toe side and the heel side of the face, vibrations are effectively absorbed by the toe side region and the back wall part of the heel side region having a large average height provided near the hitting position. Is done.

  Further, by reducing the average height of the intermediate region of the back wall, the flight distance when hitting in the central region including the sweet spot of the face is improved. That is, the energy loss of vibration consumed at the back wall is reduced and the flight distance is improved. There is a positive correlation between the height of the back wall and the vibration absorption performance. Therefore, if the average height of the back wall portion in the intermediate region is relatively small, the vibration absorbing performance in this portion is lowered. However, when the ball is hit in the center area of the face, the vibration transmitted to the golfer's hand is inherently very small, so there is no possibility of inconvenience such as deterioration of the hit feeling.

  Further, in the iron type golf club head of the present invention, when viewed from the back of the head, the upper edge of the back wall portion has a shape in which the length in the toe-heel direction gradually decreases at the substantially middle portion in the toe-heel direction. Are formed. In such a club head, since the height of the back wall portion changes smoothly, a sudden rigidity change of the back wall portion can be eliminated to improve durability, and vibration absorbing performance can be secured in a wider range.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the iron-type golf club head 1 in the toe-heel direction so that the loft angle becomes zero from the reference state where the iron-type golf club head 1 is grounded to the horizontal plane HP at a specified lie angle and loft angle (both not shown). FIG. 2 is a rear view thereof, FIG. 3 is a perspective view thereof, and FIGS. 4A to 4C are XX, YY and Z in FIG. -Z section enlarged end view, FIG. 5 shows a BB cross-sectional view of FIG.

  In the drawing, an iron type golf club head (hereinafter, simply referred to as “head” or “club head”) 1 of the present embodiment is connected to a face 2 for hitting a ball and an upper edge of the face 2 and A top surface 3 that forms the upper surface of the head, a sole surface 4 that continues to the lower edge of the face 2 and forms the bottom surface of the head, and a toe surface 5 that smoothly curves and joins between the top surface 3 and the sole surface 4 And a back surface 6 forming a surface opposite to the face 2 and a hosel portion 9 having a shaft insertion hole 9a to which a shaft (not shown) is mounted.

  When the club shaft is not mounted, the lie angle of the head 1 can be based on the center line CL of the shaft insertion hole 9a.

  The head 1 of the present embodiment includes a face plate 1A made of a metal material and a head body 1B made of a metal material different from the face plate 1A and having the face plate 1A disposed on the front surface. However, the head 1 may be formed by forging or casting one kind of metal material.

  As shown in FIGS. 1 and 4, the face plate 1 </ b> A is formed in a plate shape that constitutes a main part of the face 2, and the contour shape thereof is substantially similar to the contour of the face 2.

  The thickness t of the face plate 1A is not particularly limited. However, if the thickness is too large, the resilience of the head is lowered, and if it is too small, the strength tends to be insufficient and the durability tends to deteriorate. More preferably, it is 1.8 mm or more, more preferably 2.0 mm or more, preferably 4.5 mm or less, more preferably 4.0 mm or less, and further preferably 3.0 mm or less. The thickness t need not be constant and can be different in each part. The face 2 is provided with a plurality of face lines SC such as a concave groove for increasing the frictional force with the ball as needed.

  As shown in FIG. 4A, the head main body 1B includes an opening O penetrating in the front-rear direction of the head, a face support frame 8 provided around the head O, and a neck 7 on the face support frame 8. The hosel portion 9 is provided continuously through the hosel.

  The face support frame portion 8 is formed with substantially step-shaped receiving surfaces 8A and 8B that support the outer peripheral surface 1A1 of the face plate 1A and the peripheral portion 1A2 on the back surface. Therefore, when the ball is hit, the portion facing the opening O of the face plate 1A can be flexed freely and greatly. This is useful for improving the resilience performance of the club head 1 and increasing the flight distance of the hit ball.

  In the present embodiment, a titanium alloy is used for the face plate 1A, and stainless steel is used for the head body 1B. Needless to say, various combinations of metal materials may be used for the face plate 1A and the head body 1B. Further, the face plate 1A and the head body 1B are integrated by, for example, a joining means such as caulking, an adhesive, and / or a screw.

  A rear raised portion 10 is formed at the peripheral portion of the back surface 6 of the face 2 so as to protrude rearward from the head and extend in an annular shape. That is, the rear raised portion 10 includes a top-side raised portion 10 a extending along the top surface 3, a sole-side raised portion 10 b extending along the sole surface 4, and a toe-side raised portion extending along the toe surface 5. And a heel portion side raised portion 10d connecting the top portion side raised portion 10a and the sole portion side raised portion 10b on the heel side. As a result, a cavity C surrounded by the rear raised portion 10 and recessed toward the face 2 is formed on the back surface of the face 2. Such a cavity back structure is useful for increasing the moment of inertia of the head and stabilizing the directionality of the hit ball.

  The rear raised portion 10 of the present embodiment extends in an annular shape with a substantially constant width in the head rear view. Further, as indicated by phantom lines in FIG. 4, the raised height h of the rear raised portion 10 with respect to the face 2 smoothly increases from the top surface 3 toward the sole surface 4 side. This helps to distribute more weight to the head bottom.

  2 and 3, the sole-side raised portion 10b is provided with a back wall portion 11 that rises upward from the rear end portion without contacting the back surface of the face 2. 2, the inner surface of the sole-side raised portion 10b facing the cavity C side extends substantially flatly along the toe-heel direction.

  The back wall 11 terminates without its upper edges 13 to 17 reaching the top-side raised portion 10a. On the other hand, as shown in FIG. 5, the toe side and the heel side of the back wall part 11 are connected to the toe part side raised part 10c and the heel part side raised part 10d, respectively.

  Due to the back wall portion 11 as described above, the cavity C is opened at the back surface 6 of the head 1 as shown in FIG. 4, and the back surface and back wall of the face 2 are formed below the open cavity portion C1. It is divided into a substantially pocket-shaped undercut cavity portion C2 sandwiched between the portions 11. The depth length of the undercut cavity C2 can be arbitrarily determined as long as the gap is such that the back surface of the face 2 does not contact the back wall 11 when the ball is hit.

  In addition, the undercut cavity C2 has a vertical cross section perpendicular to the face 2 in the face vertical state (this is shown in FIGS. 4A to 4C) and the face 2 facing upward. It is formed in a cross-sectional dovetail shape in which the perpendicular depth is reduced. In other words, the back wall portion 11 of the present embodiment extends upward so as to be inclined toward the face 2 side. However, as described above, the undercut cavity C2 does not necessarily have a dovetail cross-sectional shape, and may rise up substantially parallel to the face 2, for example.

  The back wall portion 11 as described above is conspicuous at the back wall portion 11 when the vibration generated in the face 2 is transmitted to the back wall portion 11 via the sole portion side raised portion 10b when the golf ball is hit. The vibration is effectively reduced without causing resonance, and as a result, the vibration damping performance of the entire head is increased. Therefore, the impact acting on the golfer's finger during a miss shot is effectively mitigated.

  Further, as shown in FIG. 2, the back wall portion 11 includes a toe side wall portion 11t extending on the toe side and a heel side wall portion 11h extending on the heel side, and a step therebetween between the head rear view in the face vertical state. And an intermediate wall portion 11c having a smaller height than the toe side wall portion 11t and the heel side wall portion 11h. In this embodiment, the upper edge 13 of the toe side wall portion 11t and the upper edge 14 of the intermediate wall portion 11c are connected by a drooping edge 16 extending substantially vertically. Similarly, the upper edge 15 of the heel side wall portion 11h and the upper edge 14 of the intermediate wall portion 11c are connected by a drooping edge 17 extending substantially vertically. Thereby, the upper edge of the back wall part 11 is formed as what is dented by a substantially rectangular step.

Further, as shown in FIG. 2, the back wall portion 11 of the present embodiment is based on the horizontal length Wo between the most toe side position P1 and the most heel side position P2 of the open cavity portion C1. When this is virtually divided into three equal parts of the toe side region At, the intermediate region Ac, and the heel side region Ah, the following equation is satisfied.
Ht> Hc and Hh> Hc

  In the above formula, Ht is the average height of the back wall portion 11 extending over the toe side region At, Hc is the average height Hc of the back wall portion 11 extending over the intermediate region Ac, and Hh is the back wall portion 11 extending over the heel side region Ah. Is the average height. In FIGS. 2 and 4, the heights Ht, Hc, and Hh are displayed for easy understanding, although they do not coincide with the average height.

  Further, as shown in FIGS. 4 (a) to 4 (c), the average height is an undercut cavity portion in a cross section perpendicular to the face 2 in the face vertical state in each of the regions At, Ac, and Ah. A plurality of heights parallel to the face 2 between the lowest position of C2 and the highest position of the back wall 11 are measured at least in the toe-heel direction, and these are averaged.

  In the club head 1 of the present embodiment configured as described above, the average heights Ht and Hh of the back wall portion 11 in the toe side region At and the heel side region Ah are equal to the average height of the back wall portion 11 in the intermediate region Ac. Since it is formed to be larger than the height Hc, even if a ball is hit on the toe side and the heel side of the face, it is effectively uncomfortable due to the large back wall portion 11 provided near the hitting position. Vibration is absorbed.

  Further, by reducing the average height Hc of the back wall portion 11 in the intermediate region, the flight distance when hitting in the central region including the sweet spot SS of the face 2 is improved. That is, at the time of hitting the center, the vibration energy loss at the time of hitting the ball consumed by the back wall portion is reduced, and as a result, the flight distance is extended. As described above, in the club head 1 of the present embodiment, the toe side region At and the heel side region Ah located behind the toe or the heel side region Ah are positioned to increase the vibration absorption performance at the time of hitting the toe or heel side where the impact is great when hitting the ball. The average height of the back wall 11 is increased. Further, since it is not necessary to improve the vibration absorption performance at the time of hitting the center with a small impact, the height of the back wall portion 11 of the center region Ac located behind the center impact is reduced to reduce the energy loss and increase the flight distance. ing.

  Since the average height Hc of the back wall portion 11 in the intermediate area Ac is relatively small, the impact absorption performance is relatively lowered when the ball is hit in the central area including the sweet spot SS of the face 2. To do. However, when the ball is hit in the center area of the face 2, the vibration transmitted to the golfer's hand is inherently very small, so that even if the vibration absorption performance is deteriorated, the hit feeling is not deteriorated. Note that the sweet spot SS is a perpendicular leg drawn from the head center of gravity G to the face 2 as shown in FIG.

  The average height Ht of the back wall portion 11 of the toe side region At is preferably 10 mm or more, more preferably 13 mm or more, further preferably 15 mm or more, preferably 30 mm or less, more preferably 25 mm or less, Preferably it is 20 mm or less. When the average height Ht is less than 10 mm, the vibration absorption effect tends to decrease. Conversely, when the average height Ht exceeds 30 mm, the center of gravity G of the head increases and the flight distance may decrease.

  From the same viewpoint, the average height Hh of the back wall portion 11 of the heel side region Ah is preferably 7 mm or more, more preferably 8 mm or more, further preferably 9 mm or more, and preferably 25 mm or less, more preferably. Is preferably 20 mm or less, more preferably 15 mm or less.

  Here, the average height Ht of the back wall 11 of the toe side region At and the average height Hh of the back wall 11 of the heel side region Ah may be the same. However, as a result of various experiments by the inventors, it has been found that the impact transmitted to the hand is greater when the ball is hit on the toe side than on the sweet spot SS than when the ball is hit on the heel side. Therefore, the average height Ht of the back wall portion 11 in the toe side region At is made larger than the average height Hh of the back wall portion 11 in the heel side region Ah, and the vibration absorption performance on the toe side is relatively enhanced. Is particularly desirable.

  In particular, the ratio (Hh / Ht) of the average height Hh of the back wall portion 11 of the heel side region Ah to the average height Ht of the back wall portion 11 of the toe side region At is preferably 0.95 or less. Preferably it is 0.90 or less, more preferably 0.80 or less. On the other hand, if the ratio (Hh / Ht) becomes excessively small, the vibration absorption effect tends to be relatively lowered when the ball is hit on the heel side. Further, since the weight is excessively distributed on the toe side of the club head 1, the center-of-gravity distance tends to increase and the catch of the ball tends to deteriorate. From such a viewpoint, the ratio (Hh / Ht) is preferably 0.50 or more, more preferably 0.55 or more, and further preferably 0.60 or more.

  Further, the average height Hc of the back wall portion 11 in the intermediate region Ac is preferably 5 mm or more, more preferably 6 mm or more, further preferably 7 mm or more, and preferably 20 mm or less, more preferably 18 mm or less, Preferably it is 16 mm or less. If the average height Hc is less than 5 mm, the depth of center of gravity becomes shallow and the moment of inertia of the head becomes small, which may deteriorate the directionality of the hit ball at the time of a miss shot. The improvement effect tends to decrease.

  Further, the ratio (Hc / Ht) between the average height Hc of the back wall portion 11 in the intermediate region Ac and the average height Ht of the back wall portion 11 in the toe side region At is preferably 0.30 or more, more preferably Is preferably 0.35 or more, more preferably 0.40 or more, and preferably 0.90 or less, more preferably 0.70 or less, and still more preferably 0.60 or less. When the ratio (Hc / Ht) is less than 0.30, the depth of the center of gravity and the moment of inertia of the head become small, and the directionality of the hit ball at the time of a miss shot tends to deteriorate. On the contrary, if the ratio (Hc / Ht) exceeds 0.90, there is a possibility that the flight distance cannot be sufficiently improved.

  From the same viewpoint, the ratio (Hc / Hh) between the average height Hc of the back wall 11 in the intermediate region Ac and the average height Hh of the back wall 11 in the heel side region At is preferably 0.40 or more. More preferably, it is 0.45 or more, more preferably 0.50 or more, preferably 0.95 or less, more preferably 0.80 or less, and still more preferably 0.70 or less.

  In addition, although average height Ht, Hc, and Hh in each area | region of the back wall part 11 is as above-mentioned, Preferably each height measured in each area | region satisfies the above-mentioned numerical range, respectively. It is desirable.

  FIG. 6A shows a rear view of the club head in the face vertical state as an embodiment of the present invention.

  In the embodiment of FIG. 6A, the back wall portion 11 is connected to the upper edge 13 of the toe side wall portion 11t and the upper edge 14 of the intermediate wall portion 11c by a toe side oblique edge 18 that is inclined downward toward the heel side. In addition, the upper edge 15 of the heel side wall portion 11h and the upper edge 14 of the intermediate wall portion 11c are connected by a heel side oblique edge 19 that inclines downward toward the toe side.

Therefore, in the club head 1 of this embodiment, when viewed from the back of the head, the upper edge of the back wall portion 11 gradually decreases in the toe-heel direction length toward the bottom at a substantially middle portion in the toe-heel direction. A bulging substantially trapezoidal step 22 is formed. In such a club head 1, since the height of the back wall portion 11 changes smoothly, the sudden rigidity change of the back wall portion 11 is eliminated, the durability is improved, and the vibration absorbing performance can be secured in a wider range .

  FIG. 6B shows another embodiment, and the back wall portion 11 is formed such that the upper edge 13 of the toe side wall portion 11t and the upper edge 14 of the intermediate wall portion 11c face downward on the toe side. The upper edge 15 of the heel side wall part 11h and the upper edge 14 of the intermediate wall part 11c are connected by a heel side oblique edge 21 that is inclined downward toward the heel side. .

Therefore, in the club head 1 of this embodiment, when viewed from the back of the head, the upper edge of the back wall portion 11 is a lower portion in which the length in the toe-heel direction gradually increases toward the bottom at a substantially intermediate portion in the toe-heel direction. A bulging substantially trapezoidal step 22 is formed. In such a back wall part 11, a sharpened detail 25 is formed on the side of the central wall part 11c of the toe side wall part 11t and the heel side wall part 11h. The impact energy at the time of hitting the ball is concentrated in such a tapered tip 25 which is easily vibrated, and is consumed at an early stage by freely vibrating it. For this reason, most of the impact energy generated at the time of hitting the ball is more effectively consumed by the free vibration of the tapered portion 25, and a further excellent vibration absorbing effect is exhibited.

  In the embodiment of FIG. 6B, a cross section in which the sole-side raised portion 10b and the back wall portion 11 are separated is obtained in a vertical cross section perpendicular to the face 2 passing through the tapered portion 25. In this case, the height of the back wall portion 11 is specified by subtracting the maximum length of the separated portion in parallel with the face 2.

FIG. 7 shows still another embodiment.
In this embodiment, a bulging portion 26 that rises upward at a substantially middle portion in the toe-heel direction is formed on the inner surface of the sole-side raised portion 10b facing the cavity C. On the other hand, in the present embodiment, the upper edge 13 of the back side wall portion 11 extends straight in the toe-heel direction without being substantially recessed. Also in such an embodiment, the average heights Hc, Ht, and Hh of the back wall 11 can be made different in the intermediate region Ac, the toe side region At, and the heel side region Ah. Also in such an embodiment, while improving vibration absorption performance, for example, the head can be lowered in the center of gravity, and the flight distance of the hit ball can be increased.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and can be implemented with various modifications.

An iron type golf club head was prototyped based on the specifications in Table 1, and the shot feeling and the shot distance were tested. The common specifications other than those described in Table 1 are as follows.
Loft angle: 24 degrees (No. 5)
Head body material: SUS630 cast product Face member material: Ti-6Al-4V press-formed product, thickness t = 2.2 mm
Total head weight: 249g

  In any example, the back wall portion is raised substantially parallel to the face. The test method is as follows.

<Hit feel>
The same shaft is attached to each test head, and an iron-type golf club is prototyped, and 10 average golfers with handicap 15 to 25 make 10 balls of “XXIO XD (3-piece golf ball)” made by SRI Sports. A test to hit each one was performed. The impact transmitted to the hand at the time of impact (feeling reverberating in the hand) was evaluated in three stages of “good”, “normal” and “bad” depending on the sensation of the tester.

<Hit distance A>
Ten golfers with handicap 15-25 using the above test clubs hit 10 balls of SRI Sports “XXIO XD (3-piece golf ball)”, and the total distance of carry and run is measured. It was. The results are displayed as an index where the average value of 100 shots is calculated for each example and the value of Reference Example 1 is 100. The larger the value, the greater the flight distance.

<Hit distance B>
Using a swing robot made by Miyamae Co., Ltd., hitting 10 balls at a head speed of 42 m / s and sweet spot hitting using “XXIO XD (3-piece golf ball)” made by SRI Sports, carry and run The total flight distance of was measured. As a result, the average value of all 10 hits was calculated for each example, and the result was displayed as an index with the value of Reference Example 1 being 100. The larger the value, the greater the flight distance.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the examples improved the feel at impact and the flight distance in a well-balanced manner.

It is a front view of the standard state of an iron type golf club head. FIG. It is the perspective view which looked at the head from the back. (A)-(c) is XX, YY, and ZZ end elevation of FIG. It is BB sectional drawing of FIG. (A) is a rear view of the head which shows embodiment of this invention, (b) is a rear view of other embodiment. It is a rear view of the club head which shows other embodiment. (A) is the rear view of the conventional club head, (b) is the AA end elevation.

DESCRIPTION OF SYMBOLS 1 Golf club head 1A Face board 1B Head main body 2 Face 3 Top surface 4 Sole surface 5 Toe surface 6 Back surface 10 Back protruding part 10a Top part side protruding part 10b Sole part side protruding part 11 Back wall part 11t Toe side wall part 11c Middle wall Part 11h heel side wall part C cavity C1 open cavity part C2 undercut cavity part

Claims (3)

An iron-type golf club head having a top surface, a sole surface, a toe surface between them, and a face for hitting a ball,
At the peripheral edge of the back surface of the face, there is provided a rear bulge portion that bulges in the rear of the head and extends in an annular shape, thereby forming a cavity surrounded by the rear bulge portion on the back surface of the face, and along the sole surface. The back bulge portion on the sole portion side extending in the toe-heel direction is provided with a back wall portion that rises upward from its rear end portion and terminates without reaching the rear bulge portion on the top portion side. It consists of an open cavity part that opens at the back of the head, and an undercut cavity part that is formed below and sandwiched between the back wall part and the back of the face,
In the back view of the head in the face vertical state where the loft angle is tilted forward from the reference state where it is grounded to the horizontal plane at the specified lie angle and loft angle,
When the horizontal length between the most toe side position and the most heel side position of the open cavity portion is virtually divided into three equal parts of a toe side region, an intermediate region, and a heel side region, the toe side region The average height Ht of the back wall portion, the average height Hc of the back wall portion in the middle region, and the average height Hh of the back wall portion in the heel side region satisfy the following formula:
When viewed from the back of the head, the back wall portion includes a toe side wall portion extending on the toe side, a heel side wall portion extending on the heel side, and a gap between the toe side wall portion and the heel side wall portion. An intermediate wall portion having a small height,
The upper edge of the toe side wall portion and the upper edge of the intermediate wall portion are connected by a toe side oblique edge inclined downward toward the heel side,
The upper edge of the heel side wall is inclined upward toward the toe side,
Wherein the upper edge of the heel side wall portion and the upper edge of the intermediate wall portion, by being connected by the heel side oblique edge inclined to the toe side to the bottom, at the head rear view, on the back wall portion An iron-type golf club head, wherein the step is formed in a substantially trapezoidal shape in which the length in the toe-heel direction gradually decreases toward the bottom at a substantially middle portion in the toe-heel direction.
Ht> Hc and Hh> Hc   The iron-type golf club head according to claim 1, wherein an average height Ht of a back wall portion in the toe side region is larger than an average height Hh of a back wall portion in the heel side region.   3. The iron type golf club head according to claim 1, wherein each of the average height ratios (Hc / Ht) and (Hc / Hh) is 0.30 to 0.95.

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