| 摘要 |
PROBLEM TO BE SOLVED: To facilitate grinding repair and enable the combination of economical materials by forming a groove in the circumferential direction between a round blade and a plate receiver by a flank provided on the round blade and a chamfered part provided on the plate receiver. SOLUTION: A fixed shaped flank 4b gradually reducing the outer diameter as it goes to the opposite side of a blade tip 4a is provided on the outer circumferential face of a lower round blade 4 on the center side within upper and lower round blades, a plate receiver 6 is provided with a chamfered part 6a on the outer circumferential edge on the adjoining lower round blade 4 side, and a groove 8 in the circumferential direction is formed between the lower round blade 4 and the plate receiver 6. When a metal plate P is shorn by the upper round blade 3 and the lower round blade 4, by existence of the groove 8 in the circumferential direction formed on a lower rotary shaft 2 side, the burr of the section of a shorn inside metal plate P1 is not projected from the surface of the metal plate P1. Even when abrasion or broken is generated on the blade tip of the round blade, the round blade and the plate receiver 6 can be individually ground, and hence they can be easily repaired by grinding.
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