| 摘要 |
PROBLEM TO BE SOLVED: To prevent breaking unevenness generated at the time of cutting off a core piece by a parting machine by rolling a connection part of a metal sheet after slit formation, longitudinally from both upper and lower faces by rollers so as to enlarge slits. SOLUTION: Cross direction slits are formed near both cross direction side parts of a metal sheet, at specified spaces in the longitudinal direction, leaving a connection part. The metal sheet after slit formation is rolled by first stage upper and lower rollers 7a, 7b formed in protruding shape only on one side, in correspondence with the connection part to form a rolled groove part of strip shape on the upper face, and further rolled by second stage upper and lower rollers 8a, 8b formed in protruding shape only on the opposite side to the first stage rollers 7a, 7b to form a rolled groove part of strip shape on the lower face. Through these processes, the rolled groove parts continuous in the longitudinal direction are formed on both upper and lower faces of the connection part so as to prevent breaking unevenness generated to a core piece when cut off by a parting machine.
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