KR20260020211A - golf club head - Google Patents

Abstract

It aims to improve ball initial velocity, high initial velocity area, launch angle, spin, hitting feel, and durability. When the tensile strengths of the first layer (36), second layer (38), and third layer (40) constituting the face portion (14) are S1, S2, and S3, S3≥S1>S2. When a ball is struck with the face surface (1402), the first layer (36), the second layer (38), and the third layer (40) constituting the face portion (14) are deformed. However, since the second layer (38), which has the lowest tensile strength and is soft, is sandwiched between the first layer (36) and the second layer (38), which have high tensile strength and are hard, the face portion (14) is deformed within elastic deformation. Therefore, the first layer (36) is easily deformed as a surface having a widening rather than a point, which is advantageous in increasing the contact area between the face surface (1402) and the ball and in securing a long contact time between the face surface (1402) and the ball.

Description

golf club head

The present invention relates to a golf club head.

A golf club head comprising a face portion, a first metal plate, and a second metal plate supporting the first metal plate through a plurality of ribs is proposed (see Patent Document 1).

In this golf club head, the first metal plate is displaced in the direction along the face surface when struck, thereby reducing the spin amount of the ball.

Japanese Patent Gazette No. 4340177

However, in the above-mentioned conventional technology, there is a concern that the plurality of ribs may be excessively deformed when the ball is struck, and the face portion may not return to its original shape even when the ball is released from the face portion. In other words, there is a concern that the face portion may be excessively deformed, and there is room for improvement in terms of improving the ball initial speed, high initial speed area, launch angle, spin, hitting feel, and durability.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a golf club head that is advantageous in improving ball initial speed, high initial speed area, launch angle, spin, hitting feel, and durability.

In order to achieve the above object, one embodiment of the present invention is a golf club head having a hollow structure, wherein at least a portion of the face portion is composed of a first layer constituting a face surface, a second layer positioned on the opposite side of the first layer to the face surface, and a third layer positioned on the opposite side of the second layer to the first layer, wherein when the tensile strengths of the first layer, the second layer, and the third layer are S1, S2, and S3, respectively, S3 ≥ S1 > S2.

In addition, one embodiment of the present invention is characterized in that the hardness of the first layer is a durometer hardness of D75 or more and a Vickers hardness of HV520 or less, the hardness of the second layer is a durometer hardness of A10 or more and a durometer hardness of D60 or less, and the hardness of the third layer is a durometer hardness of D85 or more and a Vickers hardness of HV520 or less.

In addition, one embodiment of the present invention is characterized in that the tensile elastic modulus of the first layer is 8 GPa or more and 240 GPa or less, the tensile elastic modulus of the second layer is 0.5 MPa or more and 3000 MPa or less, and the tensile elastic modulus of the third layer is 10 GPa or more and 240 GPa or less.

In addition, one embodiment of the present invention is characterized in that the thickness of the first layer is 0.1 mm or more and 1.5 mm or less, the thickness of the second layer is 0.1 mm or more and 1.0 mm or less, and the thickness of the third layer is 2.0 mm or more and 5.0 mm or less.

In addition, one embodiment of the present invention is characterized in that the first layer is composed of any one of a metal material, a synthetic resin material, and a fiber-reinforced resin material, the second layer is composed of any one of a double-sided tape, a synthetic resin material, and an elastic material, and the third layer is composed of any one of a metal material, a synthetic resin material, and a fiber-reinforced resin material.

In addition, one embodiment of the present invention is characterized in that a thin portion that is thinner than other portions is formed in the third layer, the thin portion is configured as a concave portion formed in an open shape in the first layer on the front surface of the third layer facing the first layer, and the second layer is arranged to be filled in the concave portion.

In addition, one embodiment of the present invention is characterized in that the front surface of the third layer, excluding the concave portion, is covered and aligned with the first layer.

In addition, in one embodiment of the present invention, the golf club head has a hollow head body having a face outer periphery in which an opening is provided while leaving an outer periphery of the face portion, and a crown portion, a sole portion, and a side portion connected to the face outer periphery, and a plate-shaped third face member constituting the third layer is installed on the inner side of the head body on the inner side of the face outer periphery, a plate-shaped second face member constituting the second layer is fitted and attached to the third face member on the inner side of the face outer periphery, and a plate-shaped first face member constituting the first layer is fitted and attached to the second face member on the inner side of the face outer periphery, and the third face member has an outer peripheral surface on the inner peripheral surface of a frame-shaped inner plate portion of the face outer periphery. It is characterized in that the parts are attached by welding while facing each other, and a bead formed during the welding is received in a bead receiving space installed across the outer circumference of the third face member and the inner circumference of the attachment plate on a side away from the inside of the head body, and the bead receiving space is covered by the second face member and the first face member.

In addition, in one embodiment of the present invention, the golf club head has a hollow head body having an opening cut out at a portion of the face portion, a portion of the crown portion on the face portion side, a portion of the sole portion on the face portion side, and a portion of the side portion on the face portion side, and a third face member constituting the third layer has a third face body corresponding to the face portion, and a third flange protruding from the outer periphery of the third face body toward the head body, and a second face member constituting the second layer has a second face body that is fitted and attached to the third face body, and a second flange that protrudes from the outer periphery of the second face body toward the head body and is fitted and attached to the third flange, a portion of the crown portion on the opening portion side, a portion of the sole portion on the opening portion side, and a portion of the side portion on the face portion side, and a first face member constituting the first layer has a first face body that is fitted and attached to the second face body, and a second flange of the first face body A first flange is provided that protrudes from the outer periphery toward the head body and is fitted and attached to the second flange, and a tip end surface of the third flange is welded to abut against a tip end surface of the crown portion forming the opening, a tip end surface of the sole portion, and a tip end surface of the side portion, and a bead formed during the welding is received in a bead receiving space that is installed across the outer periphery of the third flange, the outer periphery of the crown portion, the outer periphery of the sole portion, and the outer periphery of the side portion on a side away from the inside of the head body, and the bead receiving space is covered with the second face member and the first face member.

According to one embodiment of the present invention, when a ball is struck with the face surface, the first, second, and third layers constituting the face portion are deformed, but at this time, since the soft second layer is sandwiched between the hard first and second layers, the face portion is deformed within elastic deformation, so the first layer is easily deformed as a surface having a widening rather than a point, and the contact area and contact time between the face surface and the ball can be increased.

Therefore, by securing a large contact area and contact time, the amount of backspin of the ball is reduced through the recoil effect, the ball is hit with a high launch angle and low spin, and the distance of the ball is increased.

Additionally, recoil is the phenomenon in which the elastic twist generated within the ball, caused by contact between the ball and the face, returns to its original state. In other words, it is a forward internal spin that is opposite to backspin. Therefore, as recoil increases, the amount of backspin on the ball decreases.

Additionally, since the face is curved over a large area, the ball speed becomes high over a wide range of the face surface, which is advantageous in expanding the high-speed area.

In addition, since the stress at the time of hitting is relieved by the soft second layer, the stress generated in the third layer can be relieved, which is advantageous in securing the durability of the face over a wide range of the face surface.

In addition, the soft second layer allows the size, height, and reverberation of the hitting sound to be within a range that is comfortable for the golfer, resulting in a moderately soft hitting feel and being advantageous in improving the hitting feel over a wide range of the face surface.

Figure 1 is a front view of a golf club head according to the first embodiment, viewed from the front of the face surface.
Fig. 2 (A) is a cross-sectional view taken along line A-A of Fig. 1, and (B) is a partial cross-sectional view showing a modified example.
Figures 3 (A)-(F) are cross-sectional views schematically illustrating the configuration of the face portion.
Fig. 4 (A) is a cross-sectional view schematically showing the face portion of the second embodiment, and (B) is a cross-sectional view schematically showing the face portion of the third embodiment.
Fig. 5 (A) is a cross-sectional view of a golf club head related to the fourth embodiment, and (B) is a partial cross-sectional view showing a modified example.
Fig. 6 is a cross-sectional view of a golf club head related to the fifth embodiment.
Figures 7 (A) - (E) are cross-sectional views showing a manufacturing process of a golf club head according to the sixth embodiment.
Fig. 8 is a cross-sectional view showing a first modified example of a golf club head of the first embodiment, (A) showing the state before assembly, and (B) showing the state after assembly.
Fig. 9 is a cross-sectional view showing a second modified example of the golf club head of the first embodiment, (A) showing the state before assembly, and (B) showing the state after assembly.
Fig. 10 is a cross-sectional view showing a first modified example of a golf club head of the fourth embodiment, (A) showing the state before assembly, and (B) showing the state after assembly.
Fig. 11 is a cross-sectional view showing a second modified example of a golf club head of the fourth embodiment, (A) showing the state before assembly, and (B) showing the state after assembly.
Figure 12 is a drawing showing the evaluation results of an experimental example under condition 1 in the embodiment.
Figure 13 is a drawing showing the evaluation results of an experimental example under condition 2 in the embodiment.
Figure 14 is a drawing showing the evaluation results of an experimental example under condition 3 in the embodiment.
Figure 15 is a drawing showing the evaluation results of an experimental example under condition 4 in the embodiment.

(First embodiment)

First, the first embodiment will be described.

As shown in FIG. 1 and FIG. 2(A), in the present embodiment, the golf club head (10A) is a hollow wood-shaped golf club head (driver).

Among the golf club heads (10A), the head body (12A) excluding the face portion (14) described later is composed of a metal material or a fiber-reinforced resin material (FRP), or is composed of a combination of a metal material and a fiber-reinforced resin material.

As the above metal material, one or more types such as stainless steel, maraging steel, pure titanium, titanium alloy, or aluminum alloy are used.

Examples of such titanium alloys include titanium alloys 6-4Ti and 8-1-1Ti.

As the above fiber-reinforced resin material, carbon fiber-reinforced resin material (CFRP) is used.

The golf club head (10A) has a face portion (14), a crown portion (16), a sole portion (18), and a side portion (20).

The golf club head (10A) has a hollow structure with an interior (22) (see Fig. 2(A)) surrounded by a face portion (14), a crown portion (16), a sole portion (18), and a side portion (20).

The face part (14) has a vertical height and is extended left and right.

The crown portion (16) is extended from the upper portion of the face portion (14) toward the rear with a thickness smaller than that of the face portion (14).

The surface exposed to the outside of the face (14) is the face surface (1402) that strikes the ball.

In the crown portion (16), a hosel (28) is installed that is connected to a shaft (S) at a position on the face surface (1402) side and also on the heel (24) side, and the golf club (100) is configured by connecting the shaft (S) to the hosel (28).

The sole (18) is extended backward from the lower part of the face (14).

The side section (20) is extended through the face back between the toe (24) side edge and the heel (26) side edge of the face section (14) between the crown section (16) and the sole section (18).

As shown in Fig. 2(A), the golf club head (10A) is composed of a hollow head body (12A), a plate-shaped first face member (30), and a plate-shaped second face member (32), and the face portion (14) of the golf club head (10A) is composed of the first and second face members (30, 32) and a plate portion (34) for the face portion of the head body (12A).

In other words, the face portion (14) of the golf club head (10A) is composed of a first layer (36) constituting the face surface (1402), a second layer (38) located on the opposite side of the face surface (1402) of the first layer (36), and a third layer (40) located on the opposite side of the first layer (36) of the second layer (38).

The first layer (36) is composed of a first face member (30).

The second layer (38) is composed of a second face member (32) and is attached to the face opposite to the face surface (1402) of the first face member (30).

The third layer (40) is composed of a face plate (34) of the head body (12A), and a second face member (32) is fitted and attached to the outer surface of the face plate (34).

In this embodiment, the head body (12A) and the face plate (34) are made of the same material, for example, 8-1-1Ti (cast material).

When the tensile strengths of the first layer (36), second layer (38), and third layer (40) are respectively material strengths S1, S2, and S3, S3≥S1>S2.

(hardness)

The hardness of the first layer (36) was set to be D75 or higher in durometer hardness and HV520 or lower in Vickers hardness.

The hardness of the second layer (38) was set to be durometer hardness A10 or higher and durometer hardness D60 or lower.

The hardness of the third layer (40) was set to be D85 or higher in durometer hardness and HV520 or lower in Vickers hardness.

If the hardness of the first layer (36), second layer (38), and third layer (40) are each within the above range, it is advantageous in improving the ball initial speed, high initial speed area, launch angle, spin, hitting feel, and durability described later.

If the hardness of the first layer (36), second layer (38), and third layer (40) is below the above range, the deformation of the face portion (14) at the time of hitting the ball becomes excessive (it becomes a deformation not within the elastic deformation described later), so energy loss occurs at the time of hitting the ball, and the effect of improving the initial ball speed, high initial speed area, launch angle, spin, hitting feel, and durability is reduced.

If the hardness of the first layer (36), second layer (38), and third layer (40) exceeds the above range, the deformation (bending amount) of the face portion (14) at the time of hitting is insufficient, and thus the effect of improving the initial ball speed, high initial speed area, launch angle, spin, hitting feel, and durability is reduced.

(tensile modulus)

Additionally, the tensile elastic modulus of the first layer (36) was set to be 8 GPa or more and 240 GPa or less.

The tensile elastic modulus of the second layer (38) was set to be 0.5 MPa or more and 3000 MPa or less.

The tensile elastic modulus of the third layer (40) was set to be 10 GPa or more and 240 GPa or less.

If the tensile elastic modulus of the first layer (36), second layer (38), and third layer (40) are each within the above range, it is advantageous in improving the ball initial speed, high initial speed area, launch angle, spin, hitting feel, and durability described later.

If the tensile elastic modulus of the first layer (36), second layer (38), and third layer (40) are each below the above range, the deformation of the face portion (14) at the time of hitting the ball becomes excessive (it becomes a deformation not within the elastic deformation described later), so energy loss occurs at the time of hitting the ball, and the effect of improving the initial ball speed, high initial speed area, launch angle, spin, hitting feel, and durability is reduced.

If the tensile elastic modulus of the first layer (36), second layer (38), and third layer (40) each exceeds the above range, the deformation (bending amount) of the face portion (14) at the time of hitting is insufficient, and thus the effect of improving the initial ball speed, high initial speed area, launch angle, spin, hitting feel, and durability is reduced.

(thickness)

Additionally, the thickness of the first layer (36) was set to be 0.1 mm or more and 1.5 mm or less.

The thickness of the second layer (38) was set to be 0.1 mm or more and 1.0 mm or less.

The thickness of the third layer (40) was set to be 2.0 mm or more and 5.0 mm or less.

If the thickness of the first layer (36), the second layer (38), and the third layer (40) are each within the above range, it is advantageous in improving the ball initial speed, high initial speed area, launch angle, spin, hitting feel, and durability described later.

If the thickness of the first layer (36), second layer (38), and third layer (40) is less than the above range, the deformation of the face portion (14) at the time of hitting becomes excessive (it becomes a deformation not within the elastic deformation described later), so energy loss occurs at the time of hitting, and the effect of improving the initial ball speed, high initial speed area, launch angle, spin, hitting feel, and durability is reduced.

If the thickness of the first layer (36), second layer (38), and third layer (40) each exceeds the above range, the deformation (bending amount) of the face portion (14) at the time of hitting is insufficient, and thus the effect of improving the initial ball speed, high initial speed area, launch angle, spin, hitting feel, and durability is reduced.

(ingredient)

The first layer (36) is composed of any one of a metal material, a synthetic resin material, and a fiber-reinforced resin material.

The second layer (38) is composed of one of double-sided tape, synthetic resin material, and elastic material.

The third layer (40) is composed of one of a metal material, a synthetic resin material, and a fiber-reinforced resin material.

Examples of elastic materials used as the second layer (38) include materials made of rubber or resin. Examples of rubber include natural rubber, polybutadiene rubber, styrene-butadiene rubber, isoprene rubber, etc. Examples of resin include ionomer resin, urethane resin, polyester resin, polyamide resin, etc.

In addition, as an elastic material, an elastic adhesive (42) (Fig. 3(A)) or a hot melt adhesive (sheet adhesive: thermoplastic sheet adhesive) described later can be used. The hardness is Shore A40 to 90, etc. Adhesives with soft hardness are often used as examples.

As a metal material used as the third layer (40), a rolled plate of 6-4Ti, a titanium alloy, is exemplified, for example.

In addition, the head volume is, for example, 150 cc or more and 460 cc or less, and is applicable to a golf club head (10A) such as a driver, fairway wood, or utility.

Next, specific configuration examples of the face portion (14) will be described with reference to FIGS. 3(A) to (F). In addition, the dimensions, hardness, and material names in each configuration example below are examples and do not limit the present invention.

In addition, in the examples shown in Figures 3(A) to (F), the configuration of the third layer (40) is common.

In the face portion (14) shown in Fig. 3(A), the first layer (36) is composed of CFRP (carbon fiber reinforced resin) having a thickness of 0.75 mm.

The second layer (38) is composed of an elastic adhesive (42) having a thickness of 0.2±0.1 mm (durometer hardness A87 degrees), and the second layer (38) is bonded to the first layer (36) and the third layer (40) by the adhesive force of the elastic adhesive (42).

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

In the face portion (14) shown in Fig. 3(B), the first layer (36) is configured to include CFRP having a thickness of 0.75 mm.

The second layer (38) is composed of a urethane sheet with a thickness of 0.1 mm (durometer hardness A90).

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

The second layer (38) is bonded to the CFRP of the first layer (36) by an epoxy adhesive 44A having a thickness of 0.25 mm, and is bonded to the titanium alloy of the third layer (40) by an epoxy adhesive 44B having a thickness of 0.25 mm.

Here, the hardness of the epoxy adhesive (44A, 44B) is, for example, about 75 to 90 degrees in durometer (D).

In addition, the hardness of the epoxy adhesive (44A, 44B) used in the second embodiment and the third embodiment described below both satisfies the hardness specification described above.

Accordingly, the first layer (36) is configured to include an epoxy adhesive (44A), and the third layer (40) is configured to include an epoxy adhesive (44B).

In the face portion (14) shown in Fig. 3(C), the first layer (36) is configured to include CFRP having a thickness of 0.75 mm.

The second layer (38) is composed of a double-sided tape (foaming agent) (46) having a thickness of 0.25 mm. As the double-sided tape (46), various conventionally known double-sided tapes can be used, such as double-sided tapes using an acrylic foam substrate, a urethane foam substrate, a polypropylene substrate, and a polyester substrate.

The double-sided tape (46) of the second layer (38) is bonded to the first layer (36) with an epoxy adhesive (44A) having a thickness of 0.25 mm, and is bonded to the third layer (40) with an epoxy adhesive (44B) having a thickness of 0.25 mm.

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

Accordingly, the first layer (36) is configured to include an epoxy adhesive (44A), and the third layer (40) is configured to include an epoxy adhesive (44B).

In this example, epoxy adhesive (44A, 44B) is used to reinforce the adhesive strength of the double-sided tape (46), and if there is no need to reinforce the adhesive strength of the double-sided tape (46), the epoxy adhesive (44A, 44B) can be omitted.

In addition, the second layer (38) may be formed using only an acrylic foam substrate, a urethane foam substrate, a polypropylene substrate, or a polyester substrate, excluding the adhesive component used in the double-sided tape (46).

In the face portion (14) shown in Fig. 3(D), the first layer (36) is composed of SUS (stainless steel sheet) having a thickness of 0.2 mm.

The second layer (38) is composed of an elastic adhesive (42) having a thickness of 0.2±0.1 mm (durometer hardness A87 degrees), and the second layer (38) is bonded to the first layer (36) and the third layer (40) by the adhesive force of the elastic adhesive (42).

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

In the face portion (14) illustrated in Fig. 3(E), the first layer (36) is configured to include a SUS (stainless steel sheet) having a thickness of 0.2 mm. As a substitute for the SUS (stainless steel sheet), for example, a titanium sheet having a thickness of 0.4 mm or an aluminum sheet having a thickness of 0.6 mm can be used.

The second layer (38) is composed of a urethane sheet with a thickness of 0.1 mm (durometer hardness A90).

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

The second layer (38) is bonded to the SUS (stainless steel sheet) of the first layer (36) by an epoxy adhesive (44A) having a thickness of 0.25 mm, and is bonded to the titanium alloy of the third layer (40) by an epoxy adhesive (44B) having a thickness of 0.25 mm.

Accordingly, the first layer (36) is configured to include an epoxy adhesive (44A), and the third layer (40) is configured to include an epoxy adhesive (44B).

In the face portion (14) shown in Fig. 3(F), the first layer (36) is configured to include SUS (stainless steel sheet) having a thickness of 0.2 mm.

The second layer (38) is composed of a double-sided tape (foaming agent) (46) with a thickness of 0.25 mm.

The double-sided tape (46) of the second layer (38) is bonded to the first layer (36) with an epoxy adhesive (44A) having a thickness of 0.25 mm, and is bonded to the third layer (40) with an epoxy adhesive (44B) having a thickness of 0.25 mm.

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

Accordingly, the first layer (36) is configured to include an epoxy adhesive (44A), and the third layer (40) is configured to include an epoxy adhesive (44B).

In addition, the second layer (38) may be formed using only an acrylic foam substrate, a urethane foam substrate, a polypropylene substrate, or a polyester substrate, excluding the adhesive component used in the double-sided tape (46).

In this example, epoxy adhesive (44A, 44B) is used to reinforce the adhesive strength of the double-sided tape (46), and if there is no need to reinforce the adhesive strength of the double-sided tape (46), the epoxy adhesive (44A, 44B) can be omitted.

Next, a manufacturing method of the golf club head (10A) of the present embodiment will be described. As shown in FIG. 2(A) and FIG. 3(A) to (F), first, the golf club head (10A) excluding the first layer (36) and the second layer (38) of the face portion (14) is manufactured.

Next, the second layer (38) is fitted and attached to the third layer (40) of the face portion (14), and then the first layer (36) is fitted and attached to the second layer (38).

The attachment of the second layer (38) and the first layer (36) can be accomplished using an elastic adhesive (42), a double-sided tape (46), or an epoxy adhesive (44A, 44B) as described above. For example, when a heat-curing adhesive is used as the epoxy adhesive (44A, 44B), the second layer (38) and the first layer (36) are overlapped and pressed onto the third layer (40) to cure the epoxy adhesive (44A, 44B).

In addition, if the outermost layer is CFRP, it may be acceptable to first harden the CFRP (150℃, 60 minutes) and then bond the hardened CFRP with an adhesive. It may also be acceptable to heat and warm the hardened CFRP at 120℃ for 60 minutes to conform it to the shape of the innermost layer.

In addition, as shown in Fig. 2(A), the outer surface (face surface (1402)) of the first layer (36) is raised by the thickness of the first layer (36) and the second layer (38) with respect to the outer surface of the third layer (40), and an annular step is formed by the outer surfaces of the first layer (36) and the second layer (38) with respect to the outer surface of the third layer (40).

Therefore, in order to resolve this step, a synthetic resin (48) in the shape of a ring plate with the same thickness as the step is bonded between the outer surfaces of the first layer (36) and the second layer (38) and the outer surface of the third layer (40), and then the outer surface of the first layer (36) and the synthetic resin (48) are polished to connect the outer surface of the third layer (40) and the outer surface (face surface (1402)) of the first layer (36) into a smooth curved surface.

Then, a circular painting (not shown) is applied to the outer periphery of the outer surface (face surface (1402)) of the first layer (36), the curved surface of the synthetic resin (48), and the outer surface of the third layer (40). By applying the painting in this manner, the step is concealed, and the appearance of the golf club head (10A) is improved.

In this way, a golf club head (10A) having a face portion (14) having a first layer (36), a second layer (38), and a third layer (40) is manufactured.

In addition, instead of installing such a synthetic resin (48), as shown in Fig. 2(B), in order to eliminate the cyclical step portion of the first layer (36) and the second layer (38) formed on the outer surface of the third layer (40), the portions of the first layer (36) and the second layer (38) may be processed into tapered surfaces and a paint (49) may be applied to the surface of the tapered surface to conceal the step portion and improve the appearance of the golf club head (10A).

Next, we will explain the effects of the action.

In the golf club head (10A) of the present embodiment, when the tensile strengths of the first layer (36), the second layer (38), and the third layer (40) constituting the face portion (14) are respectively material strengths S1, S2, and S3, S3≥S1>S2.

Accordingly, when the ball is struck with the face surface (1402), the first layer (36), the second layer (38), and the third layer (40) constituting the face portion (14) are deformed, but at this time, since the second layer (38), which has the lowest tensile strength and is soft, is sandwiched between the first layer (36) and the second layer (38), which have high tensile strength and are hard, the face portion (14) is deformed within elastic deformation, so the first layer (36) is easily deformed as a surface having a widening rather than a point, which is advantageous in increasing the contact area between the face surface (1402) and the ball and in securing a long contact time between the face surface (1402) and the ball.

Here, deformation within the elastic deformation of the second layer (38) does not mean deformation in a range where the face portion (14) is not deformed plastically, but rather deformation in which the shape of the face portion (14) is almost restored to its shape before deformation at the point where the ball struck by the face surface (1402) is separated from the face surface (1402).

In other words, when a ball struck by the face surface (1402) is separated from the face surface (1402), the shape of the face portion (14) is still significantly deformed, the face portion (14) is significantly deviated from its shape before deformation, and the deformation is not restored to its shape before deformation, and is not a deformation within elastic deformation.

In this case, when the face portion (14) is deformed in a manner other than elastic deformation, there is a disadvantage in that energy loss is large and a decrease in initial speed occurs.

In this way, when hitting a ball, if the contact area and contact time between the ball and the face surface (1402) increase, the amount of backspin of the ball decreases due to the recoil effect, the ball becomes high at launch angle and low spin, and the distance of the ball increases.

In addition, since the face portion (14) is bent over a large area due to deformation within the elastic deformation, the ball speed becomes high over a wide range of the face surface (1402), which is advantageous in expanding the high-speed area.

In addition, since the stress at the time of hitting is relieved by the soft second layer (38), the stress generated in the third layer (40) can be relieved, and it is advantageous in securing the durability of the face portion (14) over a wide range of the face surface (1402).

In addition, the size, height, and reverberation of the hitting sound are within a range that is pleasant to the golfer due to the soft second layer (38), and as a result, the hitting feel is appropriately soft, which is advantageous in improving the hitting feel over a wide range of the face surface (1402).

Here, the tensile strength, hardness, tensile elastic modulus, and thickness of the first layer (36), second layer (38), and third layer (40) are described.

The present invention is important in that the soft layer (second layer (38)) is appropriately deformed into a plane within elastic deformation while ensuring the durability of the golf club head. As a result, the high-speed area can be expanded without lowering the initial speed, and the distance can be increased with a high launch angle and appropriately low backspin, while also realizing a soft hitting sensation.

In order to ensure durability, it is necessary to increase the tensile strength. Since the outermost layer (first layer (36)) and the innermost layer (third layer (40)) experience greater deformation (tensile or compressive stress) when hitting a ball than the middle layer (second layer (38)), it is necessary to use high-strength materials.

Meanwhile, within elastic deformation, the soft layer (second layer (38)) that deforms into a plane must be of appropriate softness. For example, if it is too soft, energy loss occurs and the speed of the material decreases. Since the soft layer (second layer (38)) deforms into a plane appropriately within elastic deformation, its hardness becomes an important factor.

In addition, the bending stiffness (bending stiffness (EI) = longitudinal Young's modulus (E) × cross-sectional second moment (I)) is the tensile elastic modulus in this specification.

Additionally, bending stiffness is also important, and the tensile modulus and thickness of each material are related to each other.

That is, the four factors of tensile strength, hardness, tensile modulus, and thickness are intricately intertwined, and appropriately arranging them is an important point of the golf club head related to the present invention.

Next, the first and second modification examples of the first embodiment will be described with reference to FIGS. 8 and 9.

The first and second modified examples are designed to ensure that the thickness of the second layer (38) is maintained at a constant dimension.

In addition, as shown in Fig. 8(B) and Fig. 9(B), a paint (49) is applied to eliminate the cyclical step portion of the first layer (36) and the second layer (38) formed on the outer surface of the third layer (40), similar to Fig. 2(B).

As shown in Figs. 8(A) and (B), in the first modified example, the first layer (36) (first face member (30)) constituting the face surface (1402) is composed of CFRP having a thickness of 0.75 mm, the second layer (38) (second face member (32)) is composed of an elastic adhesive (42) (or hot melt adhesive), and the third layer (40) (plate for face portion (34)) is composed of a 6-4Ti rolled plate.

On the front surface of the third layer (40) (6-4Ti rolled plate), i.e., the front surface where the plate portion (34) for the face portion faces the second layer (38), a plurality of cylindrical projections (3402) having a height of 0.25 mm and a diameter of 2 mm and protruding toward the second layer (38) are installed at intervals of 15 mm in the toe heel direction and the crown sole direction.

And, since the tips of the plurality of protrusions (3402) are in contact with the rear surface of the first layer (36) (CFRP), a gap of 0.25 mm is secured between the front surface of the third layer (40) (6-4Ti rolled plate) and the rear surface of the first layer (36) (CFRP) by the protrusions (3402), and thus a second layer (38) having a thickness of 0.25 mm is formed by filling the gap with an elastic adhesive (42).

In the second modified example shown in Fig. 9, the configurations of the first layer (36), the second layer (38), and the third layer (40) are the same as in the first modified example.

As shown in Figs. 9(A) and (B), in the second modified example, on the back surface of the first layer (36) (CFRP) having a thickness of 0.75 mm, i.e., on the back surface where the first face member (30) faces the second layer (38), a plurality of cylindrical projections (3002) having a height of 0.25 mm and a diameter of 1 mm, protruding toward the second layer (38), are installed at intervals of 15 mm in the toe heel direction and the crown sole direction.

And, since the tips of the plurality of protrusions (3002) are in contact with the front surface of the third layer (40) (6-4Ti rolled plate), a gap of 0.25 mm is secured between the front surface of the third layer (40) (6-4Ti rolled plate) and the rear surface of the first layer (36) (CFRP) by the protrusions (3002), and by filling the gap with an elastic adhesive (42), a second layer (38) having a thickness of 0.25 mm is formed.

In either of the first or second modified examples, the shape of the protrusion (3402, 3002) is not limited to a cylindrical shape as long as it can secure a gap between the front surface of the third layer (40) (6-4Ti rolled plate) and the rear surface of the first layer (36) (CFRP).

According to the first and second modified examples, it is advantageous to secure the thickness of the elastic adhesive (42) constituting the second layer (38) to a constant dimension by a simple structure of installing a plurality of protrusions (3402, 3002).

(Second embodiment)

Next, the second embodiment will be described with reference to Fig. 4(A).

In addition, in the following embodiments, parts and components that are the same as those in the first embodiment are given the same reference numerals and their descriptions are omitted, and other parts are described with emphasis.

As shown in Fig. 4(A), a thin portion (4002) that is thinner than other portions is formed in the third layer (40).

The thin wall portion (4002) is composed of a concave portion (4004) formed in an open shape in the first layer (36) on the front surface of the third layer (40) facing the first layer (36).

The first layer (36) is composed of SUS (stainless steel sheet) with a thickness of 0.2 mm or CFRP (prepreg sheet) with a thickness of 0.75 mm.

The second layer (38) is arranged to be filled in the concave portion (4004).

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

In detail, the second layer (38) is formed with a shape and thickness corresponding to the concave portion (4004) and is composed of a 0.3 mm thick (durometer hardness A90 degree) urethane sheet (50A) filled into the concave portion (4004) and a 0.1 mm thick (durometer hardness A90 degree) urethane sheet (50B) installed on the front surface of the third layer (40) including the concave portion (4004) and fitted together.

And, the second layer (38) is bonded to the SUS (stainless steel sheet) or CFRP of the first layer (36) by an epoxy adhesive (44A) having a thickness of 0.25 mm, and is bonded to the titanium alloy of the third layer (40) by an epoxy adhesive (44B) having a thickness of 0.13 mm.

Accordingly, the first layer (36) and the third layer (40) are configured to include epoxy adhesive (44A, 44B).

According to the second embodiment, not only is the effect the same as that of the first embodiment achieved, but by installing a concave portion (4004) on the front surface of the third layer (40), a thin portion (4002) can be formed by partially thinning the thickness of the third layer (40), and a thin-walled structure can be formed on the face portion (14).

Therefore, for example, forming a phantom thin section (4002) to surround the center of the face surface (1402) is advantageous in increasing the amount of curvature of the face section (14), thereby increasing the initial ball speed and increasing the distance.

In addition, it is possible to form a flat structure on the face portion (14) by installing a concave portion (4004) on the back of the third layer (40), but if the flat structure on the face portion (14) is formed by installing a concave portion (4004) on the front of the third layer (40) as in the embodiment, it is advantageous in expanding the high-velocity area, securing the recoil effect, and improving durability because the surface deformation can be increased in a part close to the striking surface compared to installing a concave portion on the back of the third layer (40).

In addition, the shape or number of the thin meat portion (4002) that constitutes the sliced meat structure is not limited.

(Third embodiment)

Next, the third embodiment will be described with reference to Fig. 4(B).

The third embodiment is a modified example of the second embodiment, and differs from the second embodiment in that the front surface of the third layer (40), excluding the concave portion (4004), is directly covered and fitted to the first layer (36) without intervening the second layer (38).

In detail, the first layer (36) is composed of SUS (stainless steel sheet) with a thickness of 0.2 mm or CFRP (prepreg sheet) with a thickness of 0.75 mm.

The second layer (38) is composed of a urethane sheet (50C) with a thickness of 0.2 mm (durometer hardness A90) in a shape corresponding to the concave portion (4004) and is filled into the concave portion (4004).

The third layer (40) is composed of a titanium alloy having a thickness of 2.0 mm or more and 5.0 mm or less.

In detail, the front surface of the second layer (38) and the front surface of the third layer (40) excluding the concave portion (4004) are bonded to the SUS (stainless steel sheet) or CFRP of the first layer (36) by an epoxy adhesive (44A) having a thickness of 0.25 mm, and the portion filled in the concave portion (4004) of the second layer (38) is bonded to the concave portion (4004) (titanium alloy) of the third layer (40) by an epoxy adhesive (44B) having a thickness of 0.13 mm.

That is, the first layer (36) is composed of an epoxy adhesive (44A), and the third layer (40) is composed of an epoxy adhesive (44B).

Accordingly, the front surface of the third layer (40) excluding the concave portion (4004) and the first layer (36) are directly covered and aligned.

In this third embodiment, the effect is almost the same as in the second embodiment.

(Fourth embodiment)

Next, the fourth embodiment will be described with reference to Fig. 5(A).

In addition, in the fourth embodiment, the mutual attachment structures of the first layer (36), the second layer (38), and the third layer (40), that is, the mutual attachment structures of the first face member (52), the second face member (54), and the third face member (56) described later are the same as in the first embodiment, so their description is omitted.

The golf club head (10B) of the fourth embodiment is composed of a hollow head body (12B), a plate-shaped first face member (52), a plate-shaped second face member (54), and a plate-shaped third face member (56).

The head body (12B) has a face outer peripheral portion (60) in which an opening (58) is installed while leaving the outer peripheral portion of the face portion (14) on the face portion (14), and a crown portion (16), a sole portion (18), and a side portion (20) connected to the face outer peripheral portion (60).

The head body (12B), like the head body (12B) of the first embodiment, is composed of a metal material or a fiber-reinforced resin material (FRP), or is composed of a combination of a metal material and a fiber-reinforced resin material.

In addition, when a titanium alloy is used as a metal material constituting the head body (12B), for example, 8-1-1Ti is exemplified as the titanium alloy.

The face outer periphery (60) is configured to include a frame-shaped outer periphery plate (62) forming the outer periphery of the face surface (1402), a frame-shaped protruding plate (64) protruding from the inner periphery of the frame-shaped outer periphery plate (62) into the interior of the head body (12B), and a frame-shaped inner periphery plate (66) protruding inward from the tip of the frame-shaped protruding plate (64).

The face portion (14) of the golf club head (10B) is composed of a first layer (36) forming a face surface (1402), a second layer (38) positioned on the opposite side of the face surface (1402) of the first layer (36), and a third layer (40) positioned on the opposite side of the first layer (36) of the second layer (38).

The third layer (40) is composed of a third face member (56), and the third face member (56) is installed on the inner side of the head body (12B) on the inner side of the face outer periphery (60). Specifically, the outer periphery end surface of the third face member (56) is welded to the tip end surface of the inner periphery plate (66) of the face outer periphery (60).

The third face member (56) is composed of a metal material, for example, a rolled plate or forged metal. An example of such a metal material is a rolled plate of 6-4Ti, a titanium alloy.

In addition, the material of the third face member (56) made of a rolled plate of 6-4Ti is set so that its strength (tensile strength) is greater than that of the head body (12B) made of 8-1-1Ti (cast material). This is to maintain durability so that the face portion (14) is not destroyed when the ball is struck.

A bead receiving space (68) is installed across the outer surface of the protruding plate portion (64) located on the side away from the inside of the head body (12B) and the outer surface of the outer periphery of the third face member (56), and a bead (B) generated when welding the outer periphery of the third face member (56) to the tip end surface of the inner plate portion (66) of the outer periphery of the face (60) is received in the bead receiving space (68).

The second layer (38) is composed of a second face member (54), and the second face member (54) is attached to the surface of the third face member (56) by covering it on the inner side of the outer plate portion (62) of the face outer portion (60).

The first layer (36) is composed of a first face member (52), and the first face member (52) is attached to the surface of the second face member (54) by covering the inner side of the outer plate portion (62) of the face outer portion (60), and the face surface (1402) is composed of the surface of the outer plate portion (62) of the face outer portion (60) and the surface of the first face member (52).

The bead receiving space (68) is covered with a second face member (54) and a first face member (52).

In addition, before covering the bead receiving space (68) with the second face member (54), it is optional to fill the bead receiving space (68) with resin or adhesive, etc.

Alternatively, a convex portion having a shape corresponding to the bead receiving space (68) may be formed in advance on the second face member (54) and the bead receiving space (68) may be filled with the convex portion.

In addition, the gap (70) formed between the outer circumferential cross-sections of the first face member (52) and the second face member (54) and the outer circumferential plate portion (62) may be filled with resin or the like, or the gap (70) may be covered with paint, thereby improving the appearance of the golf club head (10B).

In addition, as shown in Fig. 5(B), when the outer circumferential cross-sections of the first face member (52) and the second face member (54) and the outer circumferential plate portion (62) are in contact without a gap and a boundary line is formed between the two, the boundary line may be covered with paint (71) or the like to conceal the boundary line and improve the appearance of the golf club head (10B).

According to the fourth embodiment, not only does it bring about the same effect as the first embodiment, but also, since the bead receiving space (68) in which the welding bead (B) formed by welding the third face member (56) and the head body (12B) is received is covered by the second face member (54) and the first face member (52), the grinding work of the welding bead (B) that was previously necessary can be omitted, which is advantageous in reducing the manufacturing cost of the golf club head (10B).

In addition, it is also conceivable to weld the third face member (56) and the head body (12B) without providing a recessed portion on the hollow portion (22) side at the welding location. However, if the weld bead (B) protrudes outward, a grinding operation (machining) of the weld bead (B) becomes necessary, which leads to an increase in manufacturing cost. Therefore, in the fourth embodiment, the structure is such that the weld bead (B) is completely accommodated by the bead accommodation space (68), eliminating the need for grinding the weld bead (B).

In addition, in the fourth embodiment, it is optional to combine the sliced meat structures of the second and third embodiments.

In addition, in the case of the fourth embodiment, the third face member (56) and the head body (12B) may be composed of different metal materials, and the third face member (56) may be composed of a metal material having higher strength than the head body (12B).

For example, the third face member (56) can be made of a 6-4Ti rolled plate, and the head body (12B) can be made of 8-1-1Ti.

In addition, in the case of the fourth embodiment, the third face member (56) and the head body (12B) may be composed of different materials, and the third face member (56) may be composed of a material having higher strength than the head body (12B).

For example, the third face member (56) can be made of a 6-4Ti rolled plate, and the head body (12B) can be made of CFRP.

In addition, in the fourth embodiment, instead of installing a bead receiving space (68), the welding bead (B) formed by welding the third face member (56) and the head body (12B) may be ground as in the prior art, and the welding location between the third face member (56) and the head body (12B) may be covered with the second face member (54) and the first face member (52). However, if done as in the fourth embodiment, it is advantageous in reducing the manufacturing cost.

Next, the first and second modified examples of the fourth embodiment will be described with reference to FIGS. 10 and 11.

The first and second modified examples are designed to ensure that the thickness of the second layer (38) is maintained at a constant dimension.

In addition, in the following FIGS. 10 and 11, in order to simplify the illustration, the illustration of the welding bead (B), the bead receiving space (68), etc. formed by welding the plate-shaped third face member (56) and the opening (58) of the head body (12B) is omitted. In addition, as shown in FIGS. 10(B) and 11(B), similarly to FIG. 5(B), a paint (71) is applied to cover the boundary line between the outer peripheral cross-sections of the first face member (52) and the second face member (54) and the outer peripheral plate portion (62).

As shown in Figs. 10(A) and (B), in the first modified example, the first layer (36) (first face member (52)) constituting the face surface (1402) is composed of CFRP having a thickness of 0.75 mm, the second layer (38) (second face member (54)) is composed of an elastic adhesive (42) (or hot melt adhesive), and the third layer (40) (third face member (56)) is composed of a 6-4Ti rolled plate.

On the front surface of the third layer (40) (6-4Ti rolled plate), i.e., the front surface where the third face member (56) faces the second layer (38), a plurality of cylindrical projections (5602) having a height of 0.25 mm and a diameter of 2 mm and protruding toward the second layer (38) are installed at intervals of 15 mm in the toe heel direction and the crown sole direction.

And, since the tips of the plurality of protrusions (5602) are in contact with the rear surface of the first layer (36) (CFRP), a gap of 0.25 mm is secured between the front surface of the third layer (40) (6-4Ti rolled plate) and the rear surface of the first layer (36) (CFRP) by the protrusions (5602), and by filling the gap with an elastic adhesive (42), a second layer (38) having a thickness of 0.25 mm is formed.

In the second modified example shown in Figs. 11(A) and (B), the configurations of the first layer (36), the second layer (38), and the third layer (40) are the same as in the first modified example.

As shown in Figs. 11(A) and (B), in the second modified example, on the back surface of the first layer (36) (CFRP) having a thickness of 0.75 mm, i.e., on the back surface where the first face member (52) faces the second layer (38), a plurality of cylindrical projections (5202) having a height of 0.25 mm and a diameter of 1 mm, protruding toward the second layer (38), are installed at intervals of 15 mm in the toe heel direction and the crown sole direction.

Since the tips of the plurality of protrusions (5202) are in contact with the front surface of the third layer (40) (6-4Ti rolled plate), a gap of 0.25 mm is secured between the front surface of the third layer (40) (6-4Ti rolled plate) and the rear surface of the first layer (36) (CFRP) by the protrusions (5202), and by filling the gap with an elastic adhesive (42), a second layer (38) having a thickness of 0.25 mm is formed.

In either of the first or second modified examples, the shape of the protrusion (5602, 5202) is not limited to a cylindrical shape as long as it can secure a gap between the front surface of the third layer (40) (6-4Ti rolled plate) and the rear surface of the first layer (36) (CFRP).

According to the first and second modified examples, it is advantageous to secure the thickness of the elastic adhesive (42) constituting the second layer (38) to a constant dimension by a simple structure in which a plurality of protrusions (5602, 5202) are installed.

In addition, it goes without saying that the same structure as the first and second modified examples can be adopted in the fifth embodiment described later.

(Fifth embodiment)

Next, the fifth embodiment will be described with reference to Fig. 6.

In addition, in the fifth embodiment, the mutual attachment structures of the first layer (36), the second layer (38), and the third layer (40), that is, the mutual attachment structures of the first face member (72), the second face member (74), and the third face member (76) described later are the same as in the first embodiment, and therefore, the description thereof is omitted.

A golf club head (10C) is composed of a hollow head body (12C), a plate-shaped first face member (72), a plate-shaped second face member (74), and a plate-shaped third face member (76).

The head body (12C) has a crown portion (16), a sole portion (18), and a side portion (20), and further has an opening portion (78) formed by cutting out a portion of the crown portion (16) on the face portion (14) side, a portion of the sole portion (18) on the face portion (14) side, and a portion of the side portion (20) on the face portion (14) side.

The head body (12C) is composed of a metal material or a fiber-reinforced resin material (FRP), or is composed of a combination of a metal material and a fiber-reinforced resin material.

In addition, when a titanium alloy is used as a metal material constituting the head body (12C), for example, 8-1-1Ti, which is a titanium alloy, is exemplified.

The face portion (14) of the golf club head (10C) is composed of a first layer (36) forming a face surface (1402), a second layer (38) located on the opposite side of the face surface (1402) of the first layer (36), and a third layer (40) located on the opposite side of the first layer (36) of the second layer (38).

The third layer (40) is composed of a third face member (76), and the third face member (76) has a third face main body (7602) corresponding to the face portion (14), and a third flange (7604) protruding from the outer periphery of the third face main body (7602) toward the head main body (12C).

The third face member (76) is composed of a metal material, for example, a rolled plate or forged metal. An example of such a metal material is a rolled plate of 6-4Ti, a titanium alloy.

In addition, the material is set so that the third face member (76) has greater strength (tensile strength) than the head body (12C).

The tip end section of the third flange (7604) is welded against the tip end section of the crown portion (16) forming the opening (78), the tip end section of the sole portion (18), and the tip end section of the side portion (20).

A bead receiving space (80) is installed across the outer periphery of the end of the third flange (7604) on the side away from the inside of the head body (12C), the outer periphery of the crown portion (16), the outer periphery of the sole portion (18), and the outer periphery of the side portion (20), and a welding bead (B) generated during welding is received in the bead receiving space (80).

The second layer (38) is composed of a second face member (74), and the second face member (74) has a second face body (7402) that is fitted and attached to a third face body (7602), and a second flange (7404) that protrudes from the outer periphery of the second face body (7402) toward the head body (12C) to cover the bead receiving space (80), and is fitted and attached to a portion of the crown portion (16) on the opening (78) side, a portion of the sole portion (18) on the opening (78) side, and a portion of the side portion (20) on the face portion (14) side.

The first layer (36) is composed of a first face member (72), and the first face member (72) has a first face body (7202) that is fitted and attached to a second face body (7402), and a first flange (7204) that protrudes from the outer periphery of the first face body (7202) toward the head body (12C) and is fitted and attached to a second flange (7404).

Therefore, the bead receiving space (80) is covered with the second face member (74) and the first face member (72).

In addition, the first flange (7204), the second flange (7404), and the third flange (7604) correspond to the portion of the crown portion (16) on the face portion (14) side cut by the opening (78), the portion of the sole portion (18) on the face portion (14) side, and the portion of the side portion (20) on the face portion (14) side.

Additionally, before covering the bead receiving space (80) with the second face member (74), it is optional to fill the bead receiving space (80) with resin, etc.

Alternatively, a convex portion having a shape corresponding to the bead receiving space (80) may be formed in advance on the second face member (74) and the bead receiving space (80) may be filled with the convex portion.

In addition, as shown in Fig. 6, the first flange (7204) (first layer (36)) and the second flange (7404) (second layer (38)) are raised by the thickness of the first layer (36) and the second layer (38) with respect to the outer surface of the head body (12C), and an annular step is formed by the end surfaces of the first flange (7204) and the second flange (7404) with respect to the outer surface of the head body (12C).

Therefore, in order to resolve this step, a synthetic resin (82) having the same thickness as the step is bonded between the tip end surfaces of the first flange (7204) and the second flange (7404) and the outer surface of the third layer (40) and the outer surface of the head body (12C), and then the first flange (7204) and the synthetic resin (82) are polished to connect the outer surface of the head body (12C) and the outer surface of the first flange (7204) into a smooth curved surface.

Then, painting is applied to the outer surface of the first flange (7204), the curved surface of the synthetic resin, and the outer surface of the head body (12C). By applying the painting in this manner, the step is concealed, and the appearance of the golf club head (10C) can be improved.

According to the fifth embodiment, not only does it bring about the same effect as the first embodiment, but also, since the bead receiving space (80) in which the welding bead (B) formed by welding the third face member (76) and the head body (12C) is received is covered by the second face member (74) and the first face member (72), the grinding work of the welding bead (B) that was previously necessary can be omitted, which is advantageous in reducing the manufacturing cost of the golf club head (10C).

In addition, in the fifth embodiment, it is optional to combine the sliced meat structures of the second and third embodiments.

In addition, in the case of the fifth embodiment, the third face member (76) and the head body (12B) may be composed of different metal materials, and the third face member (76) may be composed of a metal material having higher strength than the head body (12B).

For example, the third face member (76) can be made of a 6-4Ti rolled plate, and the head body (12C) can be made of 8-1-1Ti.

In addition, in the case of the fifth embodiment, the third face member (76) and the head body (12B) may be composed of different materials, and the third face member (76) may be composed of a material having higher strength than the head body (12B).

For example, the third face member (76) can be made of a 6-4Ti rolled plate, and the head body (12C) can be made of CFRP.

(6th embodiment)

Next, the sixth embodiment will be described with reference to Fig. 7.

The golf club head (10D) of the sixth embodiment is a modified example of the fifth embodiment, and, without installing a bead receiving space (80), the third face member (76) and the head body (12D) are welded together as in the prior art, and a welding bead (B) formed on the outside of the third face member (76) and the head body (12D) is ground, so that the welding location between the third face member (76) and the head body (12C) is covered with the second face member (74) and the first face member (72).

In addition, in the sixth embodiment, as in the fifth embodiment, the mutual attachment structures of the first layer (36), the second layer (38), and the third layer (40), that is, the mutual attachment structures of the first face member (72), the second face member (74), and the third face member (76) are the same as in the first embodiment, and therefore, the description thereof is omitted.

That is, as shown in Figs. 7(A) and (B), by welding the third face member (76) and the head body (12D), a welding bead (B) is formed on the inner side (the hollow part (22) side) of the third face member (76) and the head body (12D), and on the outer side (the side opposite to the hollow part (22)) of the third face member (76) and the head body (12D), respectively.

Next, as shown in Fig. 7(C), the welding bead (B) formed on the outer side (opposite side to the hollow part (22)) of the third face member (76) and the head body (12D) among the welding beads (B) is polished so that the outer side of the third face member (76) and the outer side of the head body (12D) are connected to a smooth curved surface.

Next, as shown in Fig. 7(D), the second layer (38) (second face member (74)) is fitted and attached to the third layer (40) (third face member (76)), and then the first layer (36) (first face member (72)) is fitted and attached to the second layer (38) (second face member (74)) of the second face member (74).

At this time, as in the fifth embodiment, an annular step is formed on the outer surface of the head body (12D) by the end surfaces of the first flange (7204) and the second flange (7404). Therefore, in order to eliminate this step, a synthetic resin (82) having the same thickness as the step is bonded between the end surfaces of the first flange (7204) and the second flange (7404), the outer surface of the third layer (40), and the outer surface of the head body (12D), and then the first flange (7204) and the synthetic resin (82) are polished to form a smooth curved surface connecting the outer surface of the head body (12D) and the outer surface of the first flange (7204).

Then, painting is applied to the outer surface of the first flange (7204), the curved surface of the synthetic resin, and the outer surface of the head body (12D). By applying the painting in this manner, the step is concealed, and the appearance of the golf club head (10D) can be improved.

In addition, instead of installing synthetic resin (82), as shown in Fig. 7(E), in order to eliminate the annular step portion of the tip end section of the first flange (7204) and the second flange (7404) formed on the outer surface of the head body (12D), the tip end portion of the first flange (7204) and the second flange (7404) may be processed into a tapered surface and a paint (83) may be applied to the surface of the tapered surface to conceal the step and improve the appearance of the golf club head (10D).

This also produces the same effect as the fifth embodiment.

Next, an experimental example of the present invention will be described.

Figures 12 to 15 are drawings showing experimental results of a golf club head related to the present invention.

A golf club head as a sample was created for each experimental example, and the following five evaluation items were measured to obtain an index (evaluation score), and the sum score of the five indices was obtained.

(1) High-speed area (sweet area)

With the center point (Pc) of the face (1402) as the center, 45 points at equal intervals in the toe heel direction and the crown sole direction were set as striking points (Pi).

Using a dedicated swing robot, a golf club was swung at 45 points of impact (Pi), and the initial speed of the golf ball was measured using a measuring device. The head speed was set at 40 m/s.

The data of the initial velocity at 45 points of impact were interpolated, and the area of the high initial velocity area on the face (1402) that is more than 98% of the maximum initial velocity of the golf ball was indexed. In addition, the data at the upper impact point (on the crown (16) side) and the data at the lower impact point (on the sole (18) side) than the center point (Pc) were weighted more heavily than the data at the upper impact point (on the crown (16) side) to match the actual impact point location used by golfers.

The data of the high-velocity area is expressed as an index with the measurement results of the golf club head of Experimental Example 1 set at 100. A higher index indicates a better evaluation.

(2) Launch angle

The launch angle obtained from the actual hitting test at the above-mentioned hitting point location was measured.

The index of Experimental Example 1 is set to 100, and a larger index indicates a larger launch angle, indicating a better evaluation.

(3) Spin amount

Based on the spin amount (backspin amount) obtained in the actual test at the above point (Pi), the index of Experimental Example 1 is set to 100, and a larger index indicates a lower spin amount and a better evaluation.

(4) Feel of the ball

The feel of the shot is dominated by the sound of the shot when the golf club head hits the ball, and generally, if the reverberation of the sound of the shot is short and low, the feel of the shot is considered soft and desirable, and is highly evaluated by golfers.

The method for evaluating the feel of the hit is as follows.

A dedicated swing robot is used to swing a golf club at a head speed of 40 m/s with the center point (Pc) as the hitting point, the hitting sound of the golf ball is measured using a sound level meter, and the vibration waveform data of the hitting sound is sampled at a predetermined sampling cycle and recorded.

Next, the reverberation parameter (T) is calculated.

The reverberation parameter (T) is a parameter that indicates the degree of attenuation of the sound of a ball. In calculating the reverberation parameter (T), first, the recorded vibration waveform data is divided into blocks (α) in which the sound pressure vibration waveform is sequentially segmented by a predetermined number of samples, for example, 100 samples, using the first sample data (time point data) as a reference number on the time axis.

Then, the sum of the squares of the vibration waveform levels for each block (Ak) of the block group (α) is calculated, and the logarithm of this sum of squares (hereinafter referred to as the block value) is calculated for each block.

Then, from each block of the block group (α), the maximum sound pressure block in which the block value is maximum is extracted as the starting block. Then, a value lower by a predetermined value (30 dB in this embodiment) from the block value of this maximum sound pressure block is set as the end block value, and among the blocks following the starting block, the end block in which the block value is first lower than or equal to the end block value is extracted.

And, the time span between the most recent sample data on the time axis of each of these starting and ending blocks is called the reverberation parameter (T).

Therefore, the reverberation parameter (T) corresponds to the reverberation time of the hitting sound, and the shorter the reverberation parameter (T), the shorter the reverberation, the softer the hitting feel, and the higher the evaluation of the hitting feel.

In this case, the data on the hitting feel was expressed as an index where the reciprocal 1/T of the reverberation parameter (T) of the golf club head of Experimental Example 1 corresponding to the comparative example is 100. A larger index indicates a better evaluation of the hitting feel.

In addition, the method for calculating the above reverberation parameter (T) can utilize, for example, the method described in Japanese Patent Publication No. 4840106, but there is no limitation on the method for evaluating the reverberation time of the hitting sound, and it is possible to obtain the reverberation time of the hitting sound using various conventionally known methods and evaluate the hitting feel.

In addition to evaluating the hitting feel by calculating the reverberation parameter or reverberation time, it is also possible to have the golfer actually swing the golf club to hit the ball and evaluate the hitting feel by listening to the hitting sound.

(5) Durability

The face surface (1402) of a golf club head fixed to a shaft was repeatedly hit with a golf ball using an air cannon, and the number of hits required until deformation or damage occurred in the face portion (14) was measured and the number of hits was indexed. The ball speed was set to 50 m/s. The hitting point location was set to the center point (Pc) of the face surface (1402).

In this case, the measurement results of the golf club head of Experimental Example 1, which corresponds to the comparative example, were expressed as an index with 100 as the value. A higher index indicates a better evaluation.

(6) Total points

The total score is the sum of the five indices of high-velocity area, launch angle, backspin, hitting feel, and durability described above.

The total score of Experimental Example 1, which corresponds to the comparative example, is set to 500, and a higher total score indicates a better evaluation.

Describe the experimental conditions.

Experimental example 1 is a comparative example and corresponds to patent document 1 (Japanese Patent Publication No. 4340177) in the prior art, and is a golf club head having a face portion composed of a first metal plate and a second metal plate supporting the first metal plate through a plurality of ribs.

Experimental example 1 does not satisfy the provisions of claim 1 and is outside the scope of the present invention.

The specifications of each part of Experimental Example 1 are as follows.

Head body material: Titanium alloy Ti-8Al-1Mo-1V

Face material: Titanium alloy Ti-6Al-4V

Loft angle 10.5°

Lie angle 59°

Head mass 200g

Head volume 460cc

The golf club head used in Experimental Example 2-25 corresponds to the present invention, is a hollow driver, and has the following specifications in common, excluding the parameters specified in each experimental example.

Loft angle 10.5°

Lie angle 59°

Head mass 200g

Head volume 460cc

In addition, the golf club head used in Experimental Example 2-25 has a structure of the fourth embodiment (Fig. 5(A)).

In addition, the materials constituting the first layer (36), second layer (38), and third layer (40) in Experimental Example 2-25 are described in Figs. 12 to 15.

In addition, examples of typical tensile strengths of materials include titanium alloy (6-4Ti) at approximately 1047 MPa, CFRP (long fiber) at approximately 1250 to 2500 MPa, polyurethane at approximately 200 to 450 MPa, polycarbonate at approximately 65 MPa, and vinyl chloride at approximately 50 MPa.

(Condition 1: Fig. 12/Experimental Example 2-8)

In addition, in the following Figures 12-15, the symbol ○ in the description column of tensile strength S3≥S1>S2 indicates that the condition of the tensile strength is satisfied, and the symbol × indicates that the condition of the tensile strength is not satisfied.

As shown in Fig. 12, Experimental Example 1 is a comparative example and is outside the scope of the present invention.

Experimental example 2-8 satisfies the tensile strength S3 ≥ S1 > S2, which is the stipulation of claim 1.

Experimental example 2-8 satisfies the provisions of claims 1, 2, 3, 4, and 5.

In addition, Experimental Example 8 satisfies the provisions of claim 6 (sliced meat structure) in addition to 1, 2, 3, 4, and 5. In addition, the sliced meat structure of Experimental Example 8 is similar to that of the third embodiment (Fig. 4(B)).

Therefore, compared to Experimental Example 1, which is outside the scope of the present invention, Experimental Example 2-8, which is within the scope of the present invention, is superior in high-speed area, launch angle, backspin, durability, hitting feel, and total score.

(Condition 2: Fig. 13/Experimental Example 9-17)

Among Experimental Examples 9-17, Experimental Examples 9, 10, 13, 16, and 17 do not satisfy the provisions of Claim 1 and at least Claim 2 (hardness of the first layer (36), second layer (38), and third layer (40)) and are outside the scope of the present invention.

The remaining experimental examples 11, 12, 14, and 15 satisfy the provisions of claim 1 and at least satisfy the provisions of claim 2.

In addition, in Fig. 13, the hardness M70 of the second layer (38) of Experimental Example 10 represents the Rockwell hardness.

Therefore, compared to experimental examples 9, 10, 13, 16, and 17, which do not satisfy the provisions of claim 2, experimental examples 11, 12, 14, and 15, which satisfy the provisions of claim 2, are superior in high-speed area, launch angle, backspin, durability, hitting feel, and total score.

(Condition 3: Fig. 14/Experimental Example 18-21)

Among Experimental Examples 18-21, Experimental Examples 18 and 19 satisfy the provisions of claim 1, but do not satisfy the provisions of claim 4 (thickness of the first layer (36), second layer (38), and third layer (40)) regarding the thickness of the second layer (38), and are outside the scope of the present invention.

The remaining experimental examples 20 and 21 satisfy the provisions of claim 1 and at least satisfy the provisions of claim 4.

Therefore, compared to experimental examples 18 and 19 that do not satisfy the provisions of claim 4, experimental examples 20 and 21 that satisfy the provisions of claim 4 are superior in high-speed area, launch angle, backspin, durability, hitting feel, and total score.

(Condition 4: Fig. 15/Experimental Example 22-24)

Experimental examples 22-24 have different head volumes, and all satisfy the provisions of claim 1-4.

Therefore, compared to Experimental Example 1, which is outside the scope of the present invention, Experimental Examples 22-24, which are within the scope of the present invention, are superior in high-speed area, launch angle, backspin, durability, hitting feel, and total score.

In addition, in this embodiment, the golf club head is described as a hollow wood-type golf club head (driver), but the present invention can of course also be applied to hollow utility or fairway woods.

100: Golf Club
10A, 10B, 10C, 10D: Golf club heads
12A, 12B, 12C, 12D: Head body
14: Face
1402: Face
16: Crown Department
18: Solbu
20: Side part
22: The Ministry of Public Administration and Security
24: Sat
26: Hill
28: Hosel
30: Absence of the first face
3002: Protrusion
32: Absence of the second face
34: Face plate
3402: Protrusion
36: First floor
38: Second floor
40: Third floor
4002: Park Yuk-bu
4004: Concave
42: Elastic adhesive
44A, 44B: Epoxy adhesive
46: Double-sided tape
48: Synthetic resin in the shape of a circular plate
49: Dojo
50A, 50B, 50C: Urethane sheet
52: Absence of the first face
5202: Protrusion
54: Absence of the second face
56: Absence of the Third Face
5602: Protrusion
58: Aperture
60: Face Outsourcing
62: Outsourcing Department
64: Protruding plate
66: Next week's judgement
68: Bead receiving space
B: Bead
70: Gap
71: Dojo
72: Absence of the first face
7202: First phase body
7204: First flange
74: Absence of the second face
7402: Second phase body
7404: Second flange
76: Absence of the Third Face
7602: Third Phase Body
7604: Third flange
78: Aperture
80: Bead receiving space
82: Synthetic resin
83: Dojo

Claims (9)

In a golf club head having a hollow structure, at least a portion of the face portion is composed of a first layer forming a face surface, a second layer positioned on the opposite side of the first layer to the face surface, and a third layer positioned on the opposite side of the second layer to the first layer,
When the tensile strengths of the first layer, the second layer, and the third layer are S1, S2, and S3, respectively, S3≥S1>S2,
A golf club head characterized by: In the first paragraph,
The hardness of the first layer is a durometer hardness of D75 or more and a Vickers hardness of HV520 or less,
The hardness of the above second layer is durometer hardness A10 or higher and durometer hardness D60 or lower,
The hardness of the third layer is a durometer hardness of D85 or more and a Vickers hardness of HV520 or less.
A golf club head characterized by: In the first paragraph,
The tensile modulus of the first layer is 8 GPa or more and 240 GPa or less,
The tensile modulus of the second layer is 0.5 MPa or more and 3000 MPa or less,
The tensile modulus of the third layer is 10 GPa or more and 240 GPa or less,
A golf club head characterized by: In the first paragraph,
The thickness of the first layer is 0.1 mm or more and 1.5 mm or less,
The thickness of the second layer is 0.1 mm or more and 1.0 mm or less,
The thickness of the third layer is 2.0 mm or more and 5.0 mm or less,
A golf club head characterized by: In the first paragraph,
The above first layer is composed of any one of a metal material, a synthetic resin material, and a fiber-reinforced resin material,
The second layer is composed of any one of double-sided tape, synthetic resin material, and elastic material,
The third layer is composed of any one of a metal material, a synthetic resin material, and a fiber-reinforced resin material.
A golf club head characterized by: In the first paragraph,
In the third layer above, a thinner part than other parts is formed,
The above-mentioned thin section is formed as a concave section in an open shape on the front surface of the third layer facing the first layer,
The second layer is arranged to be filled in the concave portion.
A golf club head characterized by: In paragraph 6,
The front surface of the third layer, excluding the concave portion, is covered and fitted to the first layer.
A golf club head characterized by: In the first paragraph,
The above golf club head has a hollow head body having a face outer periphery in which an opening is installed while leaving an outer periphery of the face portion, and a crown portion, a sole portion, and a side portion connected to the face outer periphery,
A plate-shaped third face member constituting the third layer is installed on the inner side of the head body from the inner side of the outer periphery of the face,
The second face member in the form of a plate constituting the second layer is attached to the third face member by fitting it onto the inner side of the outer periphery of the face,
The first face member in the form of a plate constituting the first layer is attached to the second face member by fitting it over the inner side of the outer periphery of the face,
The outer surface of the third face member is welded to the inner surface of the inner plate portion of the frame shape of the outer surface of the face,
The bead generated during the above welding is received in a bead receiving space installed across the outer periphery of the third face member and the inner periphery of the attachment plate on a side away from the inside of the head body,
The above bead receiving space is covered by the second face member and the first face member,
A golf club head characterized by: In the first paragraph,
The above golf club head has a hollow head body having openings cut out at the face portion, the crown portion on the face portion side, the sole portion on the face portion side, and the side portion on the face portion side,
The third face member constituting the third layer comprises a third face body corresponding to the face portion, and a third flange protruding from the outer periphery of the third face body toward the head body,
The second face member constituting the second layer comprises a second face body that is fitted and attached to the third face body, and a second flange that protrudes from the outer periphery of the second face body toward the head body and is fitted and attached to the third flange and the portion of the crown portion on the opening side, the portion of the sole portion on the opening side, and the portion of the side portion on the face side.
The first face member constituting the first layer comprises a first face body that is fitted and attached to the second face body, and a first flange that protrudes from the outer periphery of the first face body toward the head body and is fitted and attached to the second flange.
The tip end section of the third flange is welded to the tip end section of the crown portion forming the opening, the tip end section of the sole portion, and the tip end section of the side portion, and
The bead generated during the above welding is received in a bead receiving space installed across the outer circumference of the third flange, the outer circumference of the crown portion, the outer circumference of the sole portion, and the outer circumference of the side portion on a side away from the inside of the head body,
The above bead receiving space is covered by the second face member and the first face member,
A golf club head characterized by: