Golf club head and method of manufacturing same

A golf club head has an inner cavity and comprises a face member and a head main body which a front opening, which are connected to each other. The head main body comprises a sole portion, and a weight member which has a specific gravity greater than that of the head main body is fixed to an inner surface of the sole portion. A weld which fix the weight member to the sole portion is disposed at the peripheral edge of the weight member. The weight member has the width in the toe-heel direction of the head, which is smaller on its rear side than its front side.

TECHNICAL FIELD

The present invention relates to a golf club head and a method of manufacturing the same.

BACKGROUND ART

Japanese Patent No. 5576972 discloses a hollow golf club head having an inner cavity. This golf club head comprises a face member and a head main body with a front opening, which are fixed to each other by welding.

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In recent years, in order to increase the flight distance of a golf ball hit by a golf club head, the golf club head is required to lower the position of the center of gravity of the head. Lowering the position of the center of gravity brings the sweet spot of the club face closer to the club face center (namely, near the actual hitting position), so the launch angle of the hit ball is increased and the ball spin is reduced. Thus, a golf club head whose center of gravity is lowered can increases the flight distance of the hit ball.

In order to lower the position of the center of gravity of a golf club head, it is conceivable to add a weight member to a main body of the head and fix it to a sole portion thereof by welding. The welding may be possible by inserting a welding torch into the head main body through an opening of the head main body.

However, such welding work in a limited space inside the head main body is usually not easy. In particular, as the rear edge of the weight member is located at a deeper position of the head main body from the opening, the position is far from the hand of the welding operator, and the movable range of the welding torch in that location is limited because the head main body is usually formed so as to become smaller toward the rear side in its plan view and side view.

Therefore, there is a problem such that skill is required in order to accurately move the tip of the welding torch along the rear edge of the weight member, and thus productivity is deteriorated. Further, if the welding of the weight member is insufficient, there is a possibility that, by the impact repeatedly applied at the time of hitting a ball, the weight member is detached or abnormal noise is generated.

In view of the above circumstances, the present invention was made, and a primary objective of the present invention is to provide a golf club head and a manufacturing method therefor in which the position of the center of gravity of the head can be lowered without impairing productivity of the head.

According to one aspect of the present invention, a golf club head has an inner cavity and comprises a face member and a head main body with a front opening which are connected to each other, whereinthe head main body comprises a sole portion,a weight member which has a specific gravity greater than that of the head main body is fixed to an inner surface of the sole portion,a weld which fixes the weight member to the inner surface of the sole portion is disposed at a peripheral edge of the weight member, andthe weight member has the width in a toe-heel direction of the head, which is smaller on its rear side than its front side.

According to another aspect of the present invention, a method of manufacturing a golf club head having an inner cavity, comprises the steps of:preparing a face member and a head main body which has a front opening and comprises a sole portion,preparing a weight member whose specific gravity is greater than that of the head main body and whose width in a toe-heel direction of the head is smaller on its rear side than its front side,placing the weight member on an inner surface of the sole portion of the head main body,fixing the weight member to the sole portion of the head main body by inserting a welding torch into the inside of the head main body through the front opening of the head main body, and disposing a molten metal at a peripheral edge of the weight member, andconnecting the face member to the head main body after the fixing of the weight member.

The inner surface of the sole portion may be provided with a recess in which the weight member is disposed.

The weld which fixes the weight member to the sole portion of the head main body may extend from the head main body over a wall of the recess onto the weight member.

The mass of the weight member may be 10% or more of the total mass of the face member and the head main body.

The weight member may be formed in a plate shape having a thickness of not more than 10 mm.

In a plan view of the weight member, the position of the center of gravity of the weight member may be positioned on a club-face side of the midpoint in the front-back direction of the head, of the weight member.

The weight member may have a trapezoidal shape having a large width on the club-face side in the plan view.

The weight member may have a polygonal shape made up of straight sides in the plan view.

Therefore, in the golf club head according to the present invention, as the weight member is fixed to the inner surface of the sole portion of the head main body, the position of the center of gravity is lowered.

By inserting the welding torch into the inside of the head main body through the front opening of the head main body, and disposing the molten metal at the peripheral edge of the weight member, the weld which fixes the weight member to the sole portion can be formed.

Since the rear edge of the weight member is positioned at a location away from the front opening and being narrow. Thus, welding workability is poor in such narrow location in general. But, according to the present invention, the width in the toe-heel direction of the weight member is made smaller on the rear side than the front side, therefore, the deterioration in the productivity of the head can be suppressed.

Thus, according to the present invention, it is possible to provide a golf club head capable of lowering the position of the center of gravity of the head, without impairing the productivity of the head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described in detail in conjunction with accompanying drawings.

FIGS. 1-5are a perspective view, a plan view, a cross-sectional view, an exploded perspective view and a perspective view, which show a golf club head1as an embodiment of the present invention (shortly, the head1). InFIGS. 1-3, the head1under its standard state is shown.

In this application including the description and claims, dimensions, positions, directions and the like relating to the club head refer to those under the standard state of the club head unless otherwise noted.

Here, the standard state of a golf club head is such that the club head is set on a horizontal plane HP so that the central axis CL (shown inFIG. 2) of the golf club shaft (not shown) is inclined at the specified lie angle (not shown) while keeping the central axis CL on a vertical plane VP, and the club face forms the specified loft angle alpha (shown inFIG. 3). Incidentally, in the case of the club head alone, the center line of the shaft inserting hole can be used instead of the central axis of the club shaft.

“Toe-heel direction” of the head is a direction y parallel with the horizontal plane HP and the vertical plane VP.

“Front-back direction” of the head is a direction x parallel with the horizontal plane HP and orthogonal to the vertical plane VP.

“Up-down direction” of the head is a direction z orthogonal to the direction x and the direction y.

The head1in this embodiment shown inFIGS. 1 to 5has as a hollow structure with an inner cavity (i) and is formed in a shape of a typical wood type golf club head in this example. Here, the wood type golf club means at least a driver (#1), a brushy (#2), a spoon (#3), a buffy (#4), and a creek (#5). Further, the head1of the present embodiment may include heads having substantially similar shapes to those of the golf clubs listed above even if the club number or name is different from the golf clubs listed above.

As another embodiment of the present invention, the head1may be configured as a utility type golf club head.

The head1in the present embodiment comprises a face portion2, a crown portion3, a sole portion4and a side portion5, and is provided with a weight member40disposed therein.

The front surface of the face portion2forms a club face2afor hitting a ball.

The crown portion3continues from the upper edge of the face portion2and forms the upper surface of the head.

The sole portion4continues from the lower edge of the face portion2and forms the bottom surface of the head.

The side portion5connects between the crown portion3and the sole portion4and forms a side surface of the head, and the toe side edge and the heel side edge of the side portion5are connected to the toe side edge and the heel side edge of the face portion2, respectively.
The head1is provided with an inner cavity (i) defined as being surround by the face portion2, the crown portion3, the sole portion4and the side portion5.
A neck portion6having a shaft insertion hole6ainto which a tip end of a club shaft (not shown) is inserted and fixed is formed on the heel side of the crown portion3in this example as shown inFIGS. 1 and 2.
The neck portion6in this example is formed in a tubular shape protruding upward from the crown portion3.
Incidentally, the center line CL of the shaft insertion hole6acoincides with the central axis of the club shaft fixed to the head.

The head1comprises a face member20and a head main body30, which are connected to each other.

In the present embodiment, the face member20is formed in a so-called cup shape whose opening is oriented backward of the head as shown inFIGS. 1 to 5.

The face member20comprises the face portion2and a turnback7extending backward from the peripheral edge of the club face2a. Such face member20can be prepared by, for example, casting, plate pressing, forging, or the like.

The face member20is made of a metal material. As the metal material, various materials, for example, titanium, titanium alloy, stainless steel and aluminum alloy and the like can be used. In this example, a titanium alloy Ti-8Al-1Mo-1V (specific gravity about 4.2) is used.

The turnback7in this example includes a crown side turnback7awhich forms a fore part of the crown portion3, a sole side turnback7bwhich forms a fore part of the sole portion4, a toe side turnback7cwhich forms a fore part of the side portion on the toe side, and a heel side turnback7dwhich forms a fore part of the side portion on the heel side.

The head main body30in this example has an opening in its front and is formed in a so-called cup shape as shown inFIGS. 3 to 5although it is not limited to such a shape.

In this embodiment, the head main body30forms a major aft part of the head, and the face member20forms a fore part of the head.

The above-said opening is the only opening accessible to the inside of the head main body30in order to place the weight member40therein and to perform the welding operation.

The head main body30in this example is formed as a one-piece cast part made of a metal material. As the metal material, various materials, e.g. titanium, titanium alloy, stainless steel, aluminum alloy and the like can be employed. Preferably, a metal material which can be welded to the face member20is employed.

In this embodiment, the head main body30is made of the same metal material as the face member20.

The head main body30in this example comprises a crown aft part3a, a sole aft part4aand a side aft part5awhich respectively constitute a major aft part of the crown portion3, a major aft part of the sole portion4, and a major aft part of the side portion5, and the head main body30further comprises the neck portion6. Thus, the head main body30constitutes a major aft part of the head1excluding the face member20.

In this example, the face member20is fixed to the head main body30by welding the rear edge of the turnback7to the front edge of the head main body30, aligning their openings O1and O2with each other.

As a result, there is formed the weld junction32(shown inFIGS. 1 to 3) extending in the toe-heel direction, passing through the crown portion3, the sole portion4and the side portion5.

In general, a weld junction becomes thicker than portions on both sides thereof and the rigidity is liable to become higher in the vicinity of the weld junction.

In the present embodiment, since the weld junction32is positioned away from the peripheral edge of the club face2atoward the rear side, it is possible to prevent the rigidity of the face portion2from being increased by the presence of the weld junction32. Consequently, rebound performance which the face member20can exert is not inhibited, and excellent rebound performance can be obtained.

This welding of the face member20and the head main body30is performed after the weight member40has been fixed to the head main body30.

In order to obtain higher rebound performance, it is preferred that the turnback7has a length L1in the front-back direction of the head (shown inFIG. 3) which is not less than 5 mm, more preferably not less than 7 mm, for example, although not particularly limited.

Further, in order to obtain higher rebound performance, it is preferred that the crown side turnback7a, the sole side turnback7b, the toe side turnback7cand the heel side turnback7dcontinue annularly in substance, excepting a part passing over the neck portion6as shown inFIG. 4although not particularly limited.

The weight member40is fixed to the inner surface of the sole aft part4aof the head main body30as shown inFIGS. 3 to 5.

The weight member40is made of a material having a specific gravity greater than that of the head main body30in order to lower the position of the center of gravity of the head1.

Preferably, the mass of the weight member40is not less than 10% of the total mass of the face member20and the head main body30. Thereby, a large mass is distributed to the sole portion4, and the position of the center of gravity of the head1is further lowered.

As the material of the weight member40, a high specific gravity metal material is suitably used.

specifically, alloys containing tungsten W, particularly tungsten-nickel-iron alloys containing W, Ni and Fe are preferably used.

Incidentally, the specific gravity of such alloy can be increased by increasing the proportion of W in its chemical composition.

The specific gravity of the weight member40is preferably not less than 7, more preferably not less than 8, still more preferably in a range from 10 to 15.

FIG. 6shows a plan view of the head main body30in which the crown aft part3ais partially cut out.

As shown, the width in the toe-heel direction of the weight member40is such that the width W2on the rear side is smaller than the width W1on the front side.

Along the peripheral edge42of the weight member40, there is formed a weld50for fixing the weight member40to the head main body30.

That is, the weight member40is fixed to the head main body30by the use of the weld50.

The weld (or weld bead)50is formed through a welding process in advance of the above-described process to fix the head main body30to the face member20.

An example of the welding process is shown inFIG. 7.

A suitable example of the welding process is TIG welding carried out by an operator.

In advance of the welding process, the weight member40is set on the inner surface of the sole aft part4aof the head main body30.

In the welding process, first, a welding torch T is inserted into the head main body30through the front opening of the head main body30by the operator.

Then, by applying the arc of the welding torch T to the peripheral edge42of the weight member40, a molten weld pool is formed along the peripheral edge42, while supplying a welding rod B thereto.

Thereby, the molten metal52is arranged continuously along the peripheral edge42of the weight member40.

The molten metal52then become solidified and becomes the weld50(or weld bead).

Usually, the welding workability in a limited space in the cup-shaped head main body30is poor. But, by configuring the width of the weight member40as explained above, the welding workability is improved.

Namely, with respect to the width of the weight member40, the width W2on the rear side where the welding workability is poor is decreased, but the width W1on the front side where the welding is relatively easily is increased, therefore, the welding workability is improved while securing a sufficient volume for the weight member40.

Thus, in the golf club head1and its manufacturing method according to the present embodiment, it is possible to provide the golf club head1capable of achieving the improvement in the rebound performance and the lowing of the position of the center of gravity, without impairing the productivity.

The weight member40in this example has a trapezoidal shape with a pair of longer and shorter bases in its plan view, and the longer base defining the width W1is positioned on the front side.

In this example, therefore, the width in the toe-heel direction of the head of the weight member40decreases continuously from the front side to the rear side.

Aside from such trapezoidal shape, various shapes, for example as shown inFIGS. 8A, 8B and 8Cmay be employed as the shape of the weight member40in the plan view as far as the width W2on the rear side is smaller than the width W1on the front side.

The ratio of the width W2to the width W1is preferably not more than 0.9, more preferably not more than 0.8.

The width W2on the rear side may be zero as shown inFIG. 8(C).

It is preferable that the shape of the weight member40in the plan view is substantially polygonal, made up of substantially straight sides. Thereby, in the welding process, the movement of the welding torch T becomes linear, and a stable operation is possible even by hand, so the workability by hand is improved.

If the number of the sides of the polygonal shape is too much, the workability is deteriorated although each side is straight. For this reason, the number of the sides is preferably 4 or 5. Incidentally, the weight member40having such substantially polygonal shape may be provided, at one or more corners formed between the substantially straight sides, with a small arc-shaped chamfer (for example, of a radius of curvature of about 5 mm) in the plan view since such chamfer does not deteriorate the welding workability.

On the other hand, as the weight member40disposed in the sole portion is increased in the width toward the club face from the rear side, the center of gravity G of the weight member40shifts forward. As a result, the position of the center of gravity of the head1is also shifts forward, keeping a lower position. Thus, the depth of the center of gravity of the head1from the club face2ais decreased, while preventing the sweet spot of the club face2afrom becoming higher.

In order to lower the position of the center of gravity of the head1, it is desirable to reduce the thickness t (shown inFIG. 5) of the weight member40as much as possible. Preferably, the weight member40is formed in the form of a thin plate having a substantially constant thickness (t) of not more than 10 mm, more preferably not more than 5 mm.

Thereby, the center of gravity of the head1can be further lowered on the premise of the same mass.

In order to give an effective mass to the weight member40, it is necessary for the weight member40to have a sufficient volume.

In order to satisfy the two requirements of reducing the thickness of the weight member40and securing a sufficient volume, the weight member40needs to have a larger area in the plan view. This tends to make the rear part42bof the peripheral edge42of the weight member40be located further away from the front opening O2of the head main body30toward the rear side.

Even in such configuration, however, according to the manufacturing method of the present embodiment, the deterioration of the productivity of the head1can be effectively suppressed.

FIG. 9shows a cross section of the weight member40taken along line IX-IX inFIG. 6.

As shown, the weld50in this example is fused with the head main body30, but not fused with the weight member40. This is because weldability of the weight member40with the metal material constituting the weld50, namely that of the welding rod B is poor due to the high content of tungsten W which is increased to increase the specific gravity of the weight member40.
In this example, therefore, the weld50can restrain movements of the head in the front-back direction x, toe-heel direction y and up-down direction z, by its mechanical close contact with the surface of the weight member40.

Preferably, the inner surface of the sole portion4aof the head main body30is provided with a recess34, and the weight member40is disposed in the recess34as shown inFIGS. 5 and 9.

The recess34in this example has a bottom and a surrounding wall35which define a space for accommodating the weight member40, and the space has a slightly larger shape than that of the weight member40to exactly position the weight member40.

In the present embodiment, the recess34is formed in a thick part of the sole portion4aof the head main body30. As shown inFIGS. 3 and 5, the thick part is formed to surround the recess34and protrude toward the inner cavity.

In the head main body30, the thickness of the thick part is largest, and the thickness of a crown portion of the head main body is smallest as shown inFIG. 3.

The thick part in this example is further provided on the toe side of the recess34with an additional recess in which no separate weight member is disposed.

And the dimension in the front-back direction of the head, of the thick part surrounding the additional recess becomes smaller, while extending toward the toe of the head and backward of the head. Thus, more weight is distributed toward the heel of the head at a lower position.

The weld50preferably extends from the sole portion4aover the wall35onto the weight member40. Thereby, from the upper side of the weight member40, the weld50can restrain the movement of the weight member40in the up-down direction of the head.

Further, as the weld50in the state of molten metal has fluidity, and penetrates into and bridges the gap between the wall35and the weight member40. Thereby, the backlash or movements of the weight member40in the front-back direction and the toe-heel direction of the head in relation to the head main body30, can be restrained, and the occurrence of abnormal noise when hitting a ball is effectively suppressed.

Preferably, the upper edge of the wall35is higher than the upper surface of the weight member40in order to enhance the effect of the weld50restraining the movements of the weight member40.

In order to facilitate the filling of the gap between the recess34and the weight member40, it is preferred that a brazing material is placed on the surface of the recess34before the weight member40is placed in the recess34. By the heat during the welding process, such brazing material is melted, flows and fills the gap, then solidifies, so the gap between the recess34and the weight member40can be further lessened.

Depending on the combination of the metal material of the head main body30and that of the weight member40, the weld50can be fused with the head main body30as well as the weight member40. In other words, the metal material of the weld50can be such a material that is weldable with both of the head main body30and the weight member40.

FIG. 10shows an exploded perspective view of a golf club head1as another embodiment of the present invention. The differences from the former embodiment will be described, and redundant descriptions are omitted herein for clarity and conciseness by giving the same reference numbers to the parts/portions which perform the same or similar functions as in the former embodiment.

The golf club head1in this embodiment is also composed of a face member20and a head main body30.

The head main body30in this embodiment is provided with a front opening O2within the face portion2unlike the former embodiment.

The face member20is a flat or slightly curved plate without the turnback7unlike the former embodiment. The face member20constitutes a major part of the face portion2. The contour shape of the face member20may be the same as the contour shape of the face portion2, but in this embodiment, slightly smaller as shown in the figure.

The head main body30constitutes the remaining part of the head1excluding the face member20.

The above-said front opening O2is the only opening accessible to the inside of the head main body30in order to place the weight member40therein and to perform the welding operation.

In the case of a front opening like in this embodiment, the opening becomes smaller than that in the former embodiment, and the rear edge of the weight member becomes farther from the opening. Even so, according to the present invention, it is possible to prevent deterioration of the productivity.

Thus, the technical idea of the present invention can be applied to various golf club heads made using a head main body having an opening on its front side.

While detailed description has been made of especially preferable embodiments of the present invention, the present invention can be embodied in various forms without being limited to the illustrated embodiments.1golf club head20face member30head main body34recess35wall40weight member50weld