| 摘要 |
PROBLEM TO BE SOLVED: To stabilize the fly of game balls over a long period while controlling the sounds of impacts caused during striking. SOLUTION: A coiled game-ball striking member 16 mounted at the end of a striking lever 4 has a martensite layer formed on its surface layer by subjecting it to a processing method in which a shot of 40 to 200μwith hardness equal to or greater than product hardness is ejected at an ejection speed of 100m/sec or more to elevate the temperature near its surface to A3 transformation point or higher. The surface layer of the game ball striking member 16 is martensite that is high in hardness and excellent in wear resistance, while the center of the member 16 keeps its base material, so that the elasticity of the game ball striking member 16 derived from its coil shape is not deteriorated; i.e., since the hardness and the elasticity are both achieved, the member 16 suffers little wear from striking of the game balls and can stabilize the fly of the game balls over a long period and control the sounds of impacts caused during striking.
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