Striking plate of a golf club head

Abstract

The present invention provides a striking plate having an outer surface and an inner surface. The outer surface serves as a striking face formed with a plurality of grooves, and the inner surface is a highly-polished face with a surface roughness below 6.3 &mgr;m so as to eliminate surface defects that may otherwise cause contraction of impact stress. The striking plate can be integrated with a sole plate and a crown plate into a golf club head.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a striking plate for a golf club head and, more particularly, to such a striking plate which has an inner surface highly polished so as to eliminate surface defects that may otherwise cause concentration of impact stress in the striking plate during its hitting a ball.

[0003] 2. Description of Related Art

[0004] A prior art striking plate 90 for a golf club head is shown in FIG. 4. It is a curved metal piece typically made of high strength special steel or titanium alloy by a procedure of forging, punching or machining. Because the outer surface 91 i.e. the striking face of the striking plate 90 has much influence over friction, accuracy and a traveling distance of a ball, the resulting outer surface 91 is usually finish processed, for example, polished before grooves 93 are made in it.

[0005] Irrespective of the procedure the striking plate 90 is formed, fine textures of the metal material can never be disposed as uniform as desired during the formation process, thus leaving in the outer and inner surfaces 91 and 92 a number of surface defects 94 that will lead to micro-cracks when the plate 90 hits a ball.

[0006] In detail, if the striking plate 90 is formed by forging, the hot, ductile metal will produce lines of fine textures, as shown in FIGS. 5 and 6, in the surfaces 91 and 92 at where the metal makes contact with the cool die. If the striking plate 90 is formed by punching, lines of fine textures in the raw material or the rolled metal plate will remain in the surfaces 91 and 92 of the striking plate 90. And if the striking plate 90 is made by machining, the cutting tool will leave lines of fine incisions in the surfaces 91 and 92 of the striking plate 90.

[0007] Although the fine processing mentioned above will remove the surface defects from the outer surface 91 of the striking plate 90, the defects 94 are still kept intact in the inner surface 92 which is not fine processed. These residual defects 94 causes concentration of impact stress in the striking plate 90 during its hitting a ball and so degenerates the fatigue endurance of the same plate 90, for the worse, leading to micro-cracks in the striking plate 90 and shorting its life. Therefore, there is really a need to improve such a striking plate 90.

SUMMARY OF THE INVENTION

[0008] The object of the present invention is to provide a striking plate which has an inner surface highly-polished so as to eliminate concentration of impact stress, thereby providing an improved fatigue endurance and prolonged life for the striking plate.

[0009] To achieve the aforementioned object, the present invention provides a striking plate having an outer surface and an inner surface. The outer surface serves as a striking face formed with a plurality of grooves, and the inner surface is a highly-polished face with a surface roughness below 6.3 &mgr;m so as to eliminate surface defects that may otherwise cause contraction of impact stress. The striking plate can be integrated with a sole plate and a crown plate into a golf club head.

[0010] Other objects, advantages and novel features of this invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is an exploded perspective view of a club head provided with a striking plate constructed in accordance with the present invention;

[0012] FIG. 2 is a cross-sectional view of the striking plate taken along lines 2-2 in FIG. 1;

[0013] FIG. 3 is a diagram showing surface roughness on the inner surfaces of the striking plates of the present invention and of the prior arts;

[0014] FIG. 4 is a cross-sectional view of a prior art striking plate, shown a number of surface defects in an inner surface thereof;

[0015] FIG. 5 is a photograph, taken through an electro microscope, showing lines of surface defects presented as fine texture in the inner surface of the prior art striking plate; and

[0016] FIG. 6 is another photograph, also taken through an electro microscope, showing lines of surface defects presented as much finer texture in the inner surface of the prior art striking plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] The present invention is now to be described hereinafter by way of a preferred embodiment in reference to drawings.

[0018] Referring to FIGS. 1 to 3, a striking plate 10 in accordance with the present invention includes an outer surface 11 and an inner surface 12. The striking plate 10 is a curved metal piece made of high strength special steel or titanium alloy by means of forging, punching or machining. The outer surface 11, which serves as a striking face, is formed with a plurality of grooves 13 to improve the friction, accuracy and traveling distance for a golf ball.

[0019] In the present invention, the inner surface 12 is a highly-polished face, as shown in TABLE 1, which is optionally formed by electrolytic polishing, chemical polishing or shake-and-grind polishing. The highly-polished face preferably has a roughness below 1 6.3 &mgr;m and, more preferably, below 3.5 &mgr;m, so as to eliminate as more surface defects (as those designated with the reference numeral 94 in FIGS. 4 and 6) from the inner surface 12 as possible and therefore to improve the fatigue strength of the striking plate 10.

[0020] The outer surface 11 of the striking plate 10 may also be polished so. After the surfaces 11 and 12 are finished, as shown in FIG. 1, the striking plate 10 is integrated with a sole plate 20 and a crown plate 30 into a club head of a normal or super-large size. Furthermore, the resulting club head may be provided with an additional sleeve 40 that extends from the head for receiving a shaft (not shown). 1 TABLE 1 Available Roughness for the Inner surface of the striking plate 1

[0021] Referring again to FIGS. 2 and 4, the inner surface 12 of the inventive striking plate 10 in FIG. 2 is a highly-polished face with a surface roughness below 6.3 &mgr;m. This eliminates surface defects from the inner surface 12 and hence reduces the possibility of micro-cracks in the striking plate 10.

[0022] In contrast to the prior art striking plate 90 of FIG. 4, in which the inner surface 92 has a number of residual defects 94 that causes concentration of impact stress in the plate 90 during its hitting a ball and degenerates the fatigue endurance of the plate 90, the inventive striking plate 10 in FIG. 2 surely has an improved fatigue endurance and a prolonged life.

[0023] While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.

Claims

1. A striking plate for a golf club head, comprising an outer surface and an inner surface, said outer surface serving as a striking face, and said inner surface being a highly-polished face so as to eliminate surface defects in said inner surface and hence to improve fatigue endurance of said striking plate.

2. The striking plate as claimed in claim 1, wherein said striking face is formed with a plurality of grooves.

3. The striking plate as claimed in claim 1, wherein said highly-polished face is formed by electrolytic polishing.

4. The striking plate as claimed in claim 1, wherein said highly-polished face is formed by chemical polishing.

5. The striking plate as claimed in claim 1, wherein said highly-polished face is formed by shake-and-grind polishing.

6. The striking plate as claimed in claim 1, 3, 4 or 5, wherein said highly-polished face has a surface roughness below 6.3 &mgr;m.

7. The striking plate as claimed in claim 1, 3, 4 or 5, wherein said highly-polished face has a surface roughness below 3.5 &mgr;m.

8. The striking plate as claimed in claim 1, wherein said is adapted to be integrated with a sole plate and a crown plate into said golf club head.

9. The striking plate as claimed in claim 8, wherein said golf club head has an additional sleeve extending therefrom.