JPH04332573A - Head of golf club - Google Patents

Abstract

PURPOSE:To provide such a golf club head which is light in weight and whose elastic modulus is low so as to enable a beginner, a woman, and aged person having weak strength, old man, etc., to enjoy large enough flying distance and a stable trajectory. CONSTITUTION:The golf club head consists of a double structure of a shell layer 1 of high density of a metal of about 7.2-8.9 specific gravity, and a core layer 2 of low density of about 2.0-4.0 specific density formed by filling a hollow part of this shell layer 1 with coarse metallic powder, and thereafter, sintering it, and desirably, the shell layer is separated into a face surface part and a back face surface part and a temporary sintered body is formed, and thereafter, both of them are formed as a sintered body coupled at the time of regular sintering. Accordingly, such a head which is light in weight and whose elastic modulus is low as the whole specific gravity is about 4.0-6.0 and the elastic modulus is about 13000kgf per 1 square mm is obtained, and when this head is formed somewhat large to some extent and attached to a long-sized shaft, anybody can enjoy a stable trajectory and flying distance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to golf club heads, and more particularly to so-called iron golf club heads made of metal.

0002

2. Description of the Related Art Conventional iron heads of golf clubs are made as iron-based alloy blocks by forging or precision casting (lost wax).

[0003] Golf club heads made of iron have a high elastic modulus of about 20,000 kgf per square mm.
When the ball is hit, the amount of elastic deformation of the face surface is small, and the time the ball is in contact with the face surface is short, and although the distance can be achieved, it is difficult to control the direction of the ball.

[0004] For this reason, various design considerations have been made, such as changing the shape of the grooves provided on the ball's hitting face and the position of the center of gravity, thereby widening the sweet spot and achieving greater flight distance with a stable trajectory with good spin. Various heads have been developed that are designed to achieve this.

[0005] Recently, various improvements have been made in terms of materials. For example, the elastic modulus is 12,000 per square mm.
Some heads have also been commercialized using non-ferrous metals, which have a much lower elastic modulus than iron, such as beryllium-copper alloys with a weight of approximately 1.5 kgf.

[0006]

[Problem to be Solved by the Invention] However, no matter how many design improvements are made to conventional heads made of iron, as mentioned above, iron has a high elastic modulus, so it is difficult for beginners to use such heads. It is difficult to enjoy the trajectory and long flight distance, and if the ball is made of non-ferrous metal, it has the drawback that the ball hitting surface is easily dented or scratched, making it impractical.

[0007] Also, recently there has been an increase in the number of golfers with weak strength, such as women and the elderly, but in order for such golfers to be able to enjoy long distance, it is necessary to lengthen the shaft and increase the head speed. Just do it.

In this case, if the shaft is long, it will be difficult to hit the ball accurately if you miss, so it is preferable to increase the size of the head somewhat, but with iron heads, the specific gravity of the material is 7.2 to 8. Since it is high at 9, making the head larger will make it heavier, making it difficult for weaker golfers to swing the ball sufficiently.

An object of the present invention is to eliminate the drawbacks of the prior art as described above, and to provide a golf club that allows even golfers with weak strength, such as beginners, women, and the elderly, to enjoy sufficiently stable trajectory and flying distance. It is something.

0010

[Means for Solving the Problems] That is, the present invention provides a two-layer metal layer consisting of an outer shell layer of high-density metal and a core layer of low-density metal that is sintered after filling the outer shell layer with metal powder. Preferably, the outer shell layer is formed as a sintered body by a metal powder injection molding method or a slip cast method, and more preferably, the outer shell layer is separated into a face part and a back face part and brought into a pre-sintered state. When the metal powder for the core layer is filled into the outer shell layer which is formed by combining the face surface part and the back face surface part in this pre-sintered state and is sintered, the outer shell layer is main sintered and integrated. This is a unique golf club head.

[0011]

Effects of the Invention The present invention is constructed as described above, and has a two-layer structure consisting of a high-density metal outer shell layer and a low-density metal core layer, so even if an iron-based alloy is used, the head will not be damaged. As the overall apparent specific gravity becomes lighter, the elastic modulus also decreases, and these specific gravity and elastic modulus can be adjusted by adjusting the thickness of the outer shell layer and the particle size of the metal powder filled in the outer shell layer. It can be adjusted freely by adjusting the density of the layers.

[0012] As a result, since the surface is a high-density layer of metal with strong mechanical strength, the surface will not be dented or scratched even when the ball is hit, and the overall elastic modulus is low, resulting in a stable trajectory. Furthermore, since the specific gravity is light, even if the size of the head is slightly increased, it will not become heavy, and even if the force is weak, it will swing freely, and a long shaft can achieve a large distance, etc., so it can be freely adjusted to suit the various conditions of the user. The designed golf club can be easily provided.

Furthermore, if the outer shell layer is formed by a slip cast method or a metal powder injection molding method using very fine metal powder with an average particle size of 10 μm or less, it can be formed into any shape with a smooth surface and high dimensional accuracy. Moreover, it is easily formed with high density and strong mechanical strength, and furthermore, this formation becomes easier if it is formed by dividing it into a face surface portion and a back face surface portion.

[0014]

[Embodiment] Next, an embodiment of the present invention will be described based on FIGS. 1 to 4. A perspective view showing the external appearance of a head of the first embodiment is shown in FIG. is shown in FIG. 2, and as is clear from FIG. 2, the head consists of two layers: a hollow outer shell layer 1 and a core layer 2 that fills the hollow part of this outer shell layer 1. .

The outer shell layer 1 is preferably formed of an iron-based alloy in view of mechanical strength, and examples of the iron-based alloy include SUS.
It is integrally formed as a hollow body of a high-density sintered body based on the slip cast method using a base alloy.

In forming the outer shell layer 1 by the slip cast method, powder of SUS316L having an average particle size of 9.4 μm is mixed with 15 to 17% water by volume and 0.2 to 0.0% ammonium alginate as a dispersant. First, prepare a slurry by adding 5% and kneading it.

Next, the slurry is injected into the cavity of the plaster mold, and the moisture in the slurry is absorbed from the cavity surface into the plaster mold, so that an adsorption layer of the slurry formed on the cavity surface has a predetermined thickness. Discard the excess slurry in the cavity and drain it.

The slurry adsorption layer formed on the cavity surface of the plaster mold as described above is dehydrated and dried for about a day and night, and then released from the mold to obtain a molded body.Finally, this molded body is
Preliminary sintering is performed at 1000° C. for about 1.5 hours at a vacuum degree of about 1 torr to obtain a hollow pre-sintered outer shell.

In the hollow part of the pre-sintered outer shell obtained as described above, particles with an average grain size of about 100 μm and an apparent density of 1
Approximately 2.6 g of coarse iron powder per cubic cm was filled in the tap, and the temporarily sintered outer shell with the iron powder filled in the hollow part was heated to 0.2 g.
The head is sintered at 1250° C. for about 1 hour at a vacuum level of about 0.001 torr to form a two-layered head consisting of a completely sintered SUS outer shell layer 1 and an iron core layer 2.

In the head thus formed, the outer shell layer 1 has a specific gravity of 7.7 and a thickness of 3 to 4 mm on the face surface.
It is formed as a high-density metal sintered body with a thickness of about 5 to 7 mm on the sole surface, and the core layer 2 is formed as a low-density metal sintered body with a specific gravity of about 3.5, and the overall specific gravity is 5 and elastic modulus. It is light and has a low elastic modulus of 13,000 kgf per square mm.

Although not shown, the results of microscopic observation show that an alloyed bonding layer is formed at the boundary between the outer shell layer 1 and the core layer 2, and the bonding force between the two is strong, so that when the ball is hit, There is no fear that the bond between the two will collapse due to the impact force.

Next, regarding a second embodiment in which the outer shell layer is formed by separating it into a face surface portion and a back face surface portion by a metal powder injection molding method, FIG. 3 is a sectional view taken in a direction perpendicular to the face surface, and FIG. This will be explained using a sectional view taken in a direction parallel to the face surface.

As is clear from the figure, the outer shell layer 3 is separated into a face surface portion 4 which is a ball hitting surface and a back face surface portion 5 which is the opposite surface, and each is separately molded by metal powder injection molding. form.

When forming the outer shell layer 3 by metal powder injection molding, SUS304L with an average particle size of 8 μm is coated with
The thermoplastic resin is ethylene vinyl acetate resin 2.7
6%, acrylic resin 1.85%, paraffin wax 4.52% as wax, and dibutyl phthalate 1.2% as plasticizer. Injection mold according to conventional methods.

[0025] Next, the injection molded product is heated at 3 to 5°C per hour.
The injection molded product is heated slowly to about 200° C. to melt and remove the binder contained in the injection molded product, and the binder-free product is heated at 1000° C. for about 1 hour to pre-sinter.

The thus obtained pre-sintered product of the face part 4 and the back face part 5 is combined to form the outer shell layer 3, and the outer shell in which the face part 4 and the back face part 5 are combined is formed. The average particle size in the hollow part of layer 3 is 100 μm, and the apparent density is 2.6 per cubic cm.
Tap-fill with g of coarse iron powder.

Finally, as described above, the outer shell layer 3 in a pre-sintered state with coarse iron powder filled in the hollow part is heated to 0.0001 to
The outer shell layer 3 of a high-density metal sintered body with a specific gravity of about 7.6 was sintered at 1250°C for 1 hour in a vacuum of about RR and a specific gravity of 3.
．． A head is obtained consisting of two layers with a core layer 7 of about 5 mm.

The head thus formed has a light overall specific gravity of about 5, and an elastic modulus of 13,000 kgf per square mm, which is much lower than that of iron.
The face surface portion 4 and the back face surface portion 5, which were in the pre-sintered state, are firmly bonded by the final sintering to form an integrated outer shell layer 3, and this outer shell layer 3 and the core layer 7
It forms a bonding layer and is firmly bonded, so there is no fear that each bonded part will separate due to the impact force when hitting the ball.

A protruding weight part 6 with a thickness of about 15 mm is provided on a part of the back surface of the back face part 5 with a thickness of about 4 mm, and by appropriately designing the size and position of the weight part 6, a head with a wide sweet spot can be obtained.

In the above embodiments, the outer shell layer is made of iron-based alloy SU.
Although iron is used for the core layer of S, there is of course no problem in using other alloys, including non-ferrous alloys, depending on the properties required for both the outer shell layer and the core layer. Physical properties can also be improved by incorporating inorganic powder or fibrous materials such as carbon fiber into the alloy.

[0031] Furthermore, the reason why the outer shell layer was formed as a sintered body using the slip cast method or the metal powder injection molding method is because in these sintering methods, the particle size of the metal powder used is 10 μm or less. Because it is extremely fine, it has extremely high density and high mechanical strength, and has high dimensional accuracy and an extremely smooth surface, making it easy to obtain any shape without any post-processing.
Furthermore, it is extremely easy to blend inorganic powders and fibrous materials to improve physical properties, making it convenient for manufacturing heads, and of course it is also possible to form the outer shell layer by precision casting such as lost wax. .

Furthermore, although the above-mentioned embodiments are related to iron heads, it is of course possible to form so-called metal woods in the same manner, or to form ceramic heads by performing ceramic sintering instead of metal sintering. .

[0033]

[Effects of the Invention] The present invention has the structure and operation as described above, and it is possible to adjust the thickness of the high-density outer shell layer with a specific gravity of about 7.2 to 8.9, By adjusting the particle size of the metal powder filled in the core layer in a range of about 40 to 100 μm and adjusting the specific gravity of the core layer in a range of about 2.0 to 4.0, the overall specific gravity can be adjusted to 4.0 to 4.0. It can be easily adjusted to about 6.0.

[0034] As a result, it is possible to easily form a light and large head with a low elastic modulus and high surface strength, and by attaching such a head to a long shaft, even beginners, weak women, and the elderly can achieve a stable trajectory. You can fully enjoy the long flight distance.

[Brief explanation of the drawing]

[Fig. 1] Perspective view of the first embodiment,

[Figure 2]
1st embodiment AA sectional view,

[Figure 3]
A sectional view perpendicular to the face plane of the second embodiment,

FIG. 4 is a sectional view parallel to the face plane of the second embodiment.

[Explanation of symbols]

1, outer shell layer 2, core layer 3, outer shell layer 4, face surface portion 5, back face surface portion 7,
core layer

Claims (3)

[Claims] Claim 1: A two-layer metal structure consisting of a high-density metal outer shell layer and a low-density metal core layer formed by filling the outer shell layer with metal powder and sintering it. The head of a golf club. 2. The golf club head according to claim 1, wherein the outer shell layer is formed as a sintered body by a metal powder injection molding method or a slip cast method. 3. The outer shell layer is separated into a face part and a back face part and formed in a pre-sintered state, and a core layer is formed in the outer shell layer which is a combination of the face part and back face part in the pre-sintered state. 3. The golf club head according to claim 2, wherein the outer shell layer is fully sintered and integrated when the metal powder is filled and sintered.