| 摘要 |
PROBLEM TO BE SOLVED: To increase a hit rate without commanding a long ram stroke commanded by controller when a ram stroke is short like marking. SOLUTION: By a hydraulic cylinder 19 of stoke adjustable through actuation of a servo mechanism of a linear serve amplifier 53, a linear servo valve 31 in a punch press, etc., a punch P is hit by an up/down elevatable ram 21, punching is conducted on the work between a die D facing the punch P and the punch, based on a working program of a controller 15. In this working, when a ram stroke is below a stroke set value set beforehand, a hit rate is increased by switching to increase a gain of the servo mechanism so as to increase followablity of the ram 21. Further, when a ram stroke is larger than a stroke set value set beforehand in the case of normal punching, a gain of the serve mechanism is decreased, vibration and noise are reduced.
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