BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a method for manufacturing a golf club head, through the plastic deformation of metallic materials.
b) Prior Art
A golf club is made up of a head and a shaft, and it is typically classified into three types, i.e., wood, iron and putter. An iron head, as is indicated by its naming, is formed from iron or other various kinds of metallic materials. Whilst wood club heads were formed from wood materials such as persimmon in the past, they are mainly formed from metallic materials in recent years, such as so-called metal wood.
In general, methods for manufacturing a metallic golf club head are classified into two categories, i.e., casting and forging. Forging is superior to casting in that it can produce a golf club head of higher strength. Forging is a method by which a golf club head of a desired shape can be obtained by heating a metallic round rod material first, and then hammering it with a press or a hammer, using a die to thereby subject it to plastic deformation. In the broad sense of the term, “forging” includes deep drawing as well in which a rolled metallic plate is die cut and then subjected to deep drawing.
For example, when a round rod material for a head material is heated and then hammered, using a die in the manufacture of an iron club head by forging, a surplus amount of the head material becomes a burr. If the burr is large, the forged head is deburred, using a trimming die before the head material gets cool.
Normally, the head material is gradually finished to a final shape, through multi-stage forging process. Large burrs are produced at a comparatively early stage in such forging process. When the forged head material is close to the final shape as the forging process proceeds, surplus amount of the material is decreased, and thus burrs also become smaller.
In the past, small burrs were typically removed by grinding process, using an endless paper, or by a cutting machine.
In the case of grinding process, using an endless paper, however, as the grinding process is manually performed by an operator, the removing amount of burrs varies widely from operator to operator so that the constant configuration and weight of the heads could not be obtained. If the configuration and weight of heads vary, post-process trimming would be needed, thus causing unnecessary increase in manufacturing costs.
- SUMMARY OF THE INVENTION
On the other hand, in the case of machining process, using a cutting machine, the removal of burrs is comparatively easy in the outlines of a flat face portion, while it is substantially impossible to remove burrs in a hosel or a rise-up portion thereof. Accordingly, the removal of burrs in the hosel portion or a rise-up portion thereof eventually has to be carried out by a manual grinding by a human being.
Accordingly, it is a main object of the present invention to provide a method for manufacturing a golf club head through the plastic deformation of a metallic material, which enables the removing of burrs without causing deviations in configuration and weight of a head.
To attain the above object, there is provided, in accordance with an embodiment of the invention, a method for manufacturing a golf club head, having a face formed on a front and a shaft attachment portion formed on one side by subjecting a metallic material to plastic deformation step, wherein burrs produced during the plastic deformation step are removed, using a laser processing machine.
BRIEF DESCRIPTION OF THE DRAWINGS
Accordingly, it is possible to obtain a club head of constant configuration and weight, by setting the action of the laser processing machine in advance. Further, as all the burrs can be removed at one burr-removing step, manufacturing costs can be reduced
Other objects, features and advantages of the invention will be apparent to those skilled in the art from the following description of the preferred embodiments of the invention, wherein reference is made to the accompanying drawings, of which:
FIG. 1 is a perspective view of a golf club head which is under a forging process according to an embodiment of the invention.
FIG. 2 is a section of a golf club head which is under a forging process according to an embodiment of the invention.
FIG. 3 is a front view of a golf club head which is under a forging process according to an embodiment of the invention.
FIG. 4 is a rear perspective view of a golf club head which is finished to a final shape according to an embodiment of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 5 is a front view of a golf club head which is finished according to an embodiment of the invention.
Hereinafter will be described embodiments of the invention with reference to the attached drawings, in which an iron golf club is described as an example.
As shown in FIGS. 4 and 5, an iron golf club is made up of a head 1 and a shaft 2, of which the head 1 is made from a metallic material such as low-carbon steel, stainless steel or titanium-based alloy, including a face 3 for striking balls on a front, a sole 4 on a bottom, a heel 5 on one side, a toe 8 on the other side, a shaft attachment portion 6 provided at an upper part of the heal 5 for connecting the shaft 2 thereto and a top 7 at a top portion, respectively. A rear surface of the head 1 is formed with a concave portion 9 called “cavity”, substantially opposite to the face 3. The concave portion 9 includes a rear face body 9A thereinside, defining an upper peripheral face 10 on its inside top, a lower peripheral face 11 formed on its inside bottom, said lower peripheral face 11 spaced a thickness h away from the sole 4, a first peripheral face 12 formed on a first side and a second peripheral face 13 formed on a second side, respectively. Reference numeral 14 designates lateral grooves called score lines formed on the face 3. In the center of the rear face body 9A is formed a small protrusion 15 which is laterally elongated to improve the design attractiveness. A groove 16 is formed in the vicinity of the rear face body 9A from a first side peripheral surface 12 to a second side peripheral surface 13 on the lower peripheral surface 11.
Next, a method for manufacturing the head 1 will be described.
For a raw material processing step, a round bar (not shown) made from a metallic material such as low carbon steel, stainless steel, titanium-based alloy is cut to a predetermined length to form a round bar material. Next, the round bar material is heated to form a head body 1A through a hot forging step, as shown in FIGS. 1 to 3. As it is difficult to form the head 1 at one stroke, the forging step includes rolling and multi-step forging such as preforming, intermediate forging and finish forging, using an upper die 15 and a lower die 16. By performing the forging process through plural strokes, the head material is gradually stretched due to the plastic deformation in small steps so as to be finished to a final configuration. In the meantime, different upper die 15 and lower die 16 are exclusively used for the above-mentioned preforming, intermediate forging, and final forging, respectively.
Reference numeral 17 designates so-called burrs or flash produced during the forging step. As comparatively large burrs are created from the round bar material at a first forging stroke and in comparatively earlier forging processes, such burrs are removed, using a trimming die before the material gets cool. Smaller burrs are created as the forging step proceeds to bring the material close to a final configuration of the head. After the last forging stroke, the head body 1A is placed in a receiving die (not shown), and then the burrs 17 are completely removed by cutting, using a laser processing machine (not shown). In that case, the laser irradiation from the laser processing machine is set in advance.
Through the forging step are formed a face corresponding portion 3A, a sole corresponding portion 4A, a heel corresponding portion 5A, a shaft attachment portion corresponding portion 6A, a top corresponding portion 7A, a toe corresponding portion 8A and a concave portion corresponding portion 9′, which correspond to the face 3, sole 4, heel 5, shaft attachment portion 6, top 7, toe 8 and concave portion 9, respectively. The concave portion corresponding portion 9′ includes a rear face body corresponding portion 9′A thereinside, defining an upper peripheral face corresponding portion 10A on its inside top, a lower peripheral face corresponding portion 11A formed on its inside bottom, said lower peripheral face corresponding portion 11A spaced a thickness H away from the sole corresponding portion 4A, a first peripheral face corresponding portion 12A formed on a first side and a second peripheral face corresponding portion 13A formed on a second side, respectively. In the meantime, the thickness H is larger than the aforesaid thickness h.
Next, the head body 1A thus formed through the forging step is subjected to a cutting process. Any suitable cutting process is chosen, corresponding to the configuration and design of the head 1 and the concave portion 9 in a final product. Specifically, cutting process with a turning tool or a milling tool may be performed. In a preferred form of the invention, an end mill (not shown) such as a shank type milling cutter, having cutting edges on an outer peripheral face and an end face, is used to perform the cutting process. As shown in FIGS. 4 and 5, the rear face body corresponding portion 9′A and the lower peripheral face corresponding portion 11A are cut to form the rear face body 9A in a manner decreasing the thickness of the face 3 and the lower peripheral surface 11 in a manner decreasing the thickness of the sole 4, respectively. The lower peripheral surface 11 is concaved so as to define an undercut shape. In other words, the thickness h defined from the sole 4 and the lower peripheral face 11 may be substantially the same on the rear face body 9A side and the tip end 11Z side, or otherwise, may be smaller on the rear face body 9A side than on the tip end 11Z side. During the cutting process, the aforesaid small protrusion 15 is formed in the rear face body 9A, while the groove 16 is formed adjacent to the rear face body 9A on the lower peripheral surface 11.
Thereafter, the finishing process is performed. The finishing process includes: surface polishing; the forming of the lateral grooves 14; drilling for forming a hole 20 in a shaft center of the shaft attachment portion 6 for fitting the lower end of the shaft 2 thereinto; reaming; imprinting; plating; sandblasting; coloring, and the like.
According to the foregoing embodiment, there is provided a method for manufacturing a golf club head, having the face 3 formed on a front and the shaft attachment portion 6 formed on one side by subjecting a metallic material to the plastic deformation, wherein the burrs 17 produced during the plastic deformation at the time of the forging step are removed, using a laser processing machine with the action thereof being set in advance, whereby the constant configuration and weight of the head body 1A can be obtained. Further, as all the burrs 17 can be removed through a single step, the costs of removing the burrs 17 can be reduced to about ¼ to ⅕ of those of conventional methods, thus enabling the reduction of manufacturing costs. Furthermore, as a smooth cut surface can be obtained after removing the burrs 17, thus enabling an operator to carry out a cutting process with reference to the smooth cut surface. As a result, it is possible to make the configuration and weight of the head body 1A constant, thus enabling an operator to proceed with the subsequent processes as originally designed, whereby it is possible to manufacture products with constant qualities and less deviations.
Incidentally, the present invention should not be limited to the foregoing embodiments, but may be variously modified within a scope of the invention. Although hot forging is taken as an example of the plastic deformation process, other plastic deformation processes may be employed, such as cold forging and cold pressing. Further, the golf club head 1 should not be limited to an iron golf club, but may be a metallic wood golf club. Alternatively, the small protrusion 15 and the groove 16 do not always have to be formed in the concave portion 9, or otherwise, a protrusion of different dimension and configuration than that of the embodiment may be formed. It should be noted that a plurality of protrusions may be provided.