| 摘要 |
PURPOSE: To realize stable punching and to improve a hot rate even for punching that requires a large punching force. CONSTITUTION: A forward/backward control means 43 is provided in a punch press in which a ram 6 is elevated by a servo motor 12 through a crank mechanism 13 and a toggle mechanism 8. The forward/reverse control means 43 controls the servo motor 12 to that a crank plate 13a rotates forward/backward only in the right half region ER. The right half region ER means a rotational angle region in which the connecting point C for the advance/retract member of the crank plate 13a moves away from a toggle mechanism 8 more than the rotational angle corresponding to the approximate bottom dead center BDC of the ram 6. The forward/backward control means 43 may be one that allows forward/backward rotation within 90 deg. inclusive. Further, it may be limited to a rotational range up to a standby rotational angle HHθ, and the standby position HH for the elevation of the ram 6 may be set lower than the top dead point.
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