| 摘要 |
PROBLEM TO BE SOLVED: To appropriately punch a high silicon steel plate without using a special press machine, etc., at a normal temp. and to secure a long tool life. SOLUTION: A high silicon steel plate having 4.0-7.0 wt.% Si is punched under a clearance of 2-10% of a plate thickness of a steel plate to be punched by using a tool having a corner curvature radius R larger than a plate thickness of the steel plate to be punched. When conducting plural stage punchings by sequential dies, at least one time punching after a second punching is conducted using the tool having a gradient of 0.3-1.5% to a cutting edge in a feed direction of the steel plate to be punched or orthogonal thereto. The steel plate to be punched is controlled using a moving stopper, a load of the moving stopper is regulated to 25-80% of a max shear load. Further, punching uses a cemented carbide allot tool having an average grain size of a hard phase of <=3μm. Punching is conducted using either of a tool having the coating of one or more kinds among TiCN, TiN, TiC, TiAlN on a tool surface.
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