| 摘要 |
A controller (10) for a die cushion mechanism (20) includes: a spring element (30) that is displaced according to force between the die cushion mechanism and a slide (24); a force instructor (51) that instructs force; a force detector (21) that detects force; and a speed instruction generator (52) that generates a speed instruction (C2) of the servo motor (18), based on a force instruction value (C1) instructed by the force instructor and a force detection value (D1) detected by the force detector. The speed instruction generator generates the speed instruction by multiplying a force gain (G0) by a force difference (”l) determined from a difference between the force instruction value and the force detection value. The speed instruction generator changes the force gain, based on a spring constant corresponding value (k) of the spring element determined from a force indicator (F) that works between the slide and the die cushion. With this arrangement, the die cushion mechanism can be controlled with high precision, even when a mechanical characteristic changes. A force indicator is a force instruction value or a force detection value. In place of the force indicator, a spring constant corresponding value can be determined according to displacement of the spring element or a position of the die cushion mechanism. |
