| 摘要 |
PROBLEM TO BE SOLVED: To prevent a marking ink from being stuck to a press metal die and to prevent the sharpness of the metal die from being lowered due to ink sticking by performing marking within an area to be punched as a resonant disc while avoiding a peripheral edge part when marking a resonant disc material for discriminating the front and rear surfaces of the resonant disc. SOLUTION: Marking is applied within the area to be punched as a resonant disc 13 while avoiding the peripheral edge part of the resonant disc 13 so as not to cross an area outline. Thus, in the case of punching with a press working machine, the ink of marking 11 can be prevented from being stuck on the press metal die without making the press metal die cross/contact the marking 11. Therefore, the sharpness can be prevented from being lowered by ink sticking. Further, marking 11 is applied to a side face opposite to a sitting plane at the time of placing the resonant disc 13 on the step part of an electric/acoustic converter. Besides, the resonant disc material 1 is punched on the upper surface side, where return caused by punching occurs, namely, on a side face opposite to the sitting plane.
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