Patent ID: 8651019
Filing Date: 2014-02-18
Classification: B30B,C11D

Abstract:
1. A control method for a crank press, the crank press including a machine body, a slider, a motor driver, a servo motor which is coupled to the slider and which is coupled to and driven by the motor driver to bring about movement of the slider with respect to the machine body, and a command generator for generating a position command which is associated with control of the motor driver, the control method comprising the steps of: a) storing in a memory at least one relation between an angle value and each of an upper torsion limit and an upper load limit corresponding thereto; b) measuring an angle value associated with operation of the servo motor; c) generating a strain value corresponding to deformation of the machine body during movement of the slider within a pressing operation, and converting the strain value into a converted load value; d) calculating a torque command value based on the position command, reading from the memory the upper torsion limit corresponding to the angle value measured in step b), determining whether the torque command value exceeds the upper torsion limit, outputting the torque command value to the motor driver for driving the servo motor according to the torque command value when the torque command value does not exceed the upper torsion limit, and outputting the upper torsion limit to the motor driver for driving the servo motor according to the upper torsion limit when the torque command value exceeds the upper torsion limit; and e) reading from the memory the upper load limit corresponding to the angle value measured in step b), determining whether the converted load value exceeds the upper load limit, and controlling the motor driver to stop driving the servo motor when the converted load value exceeds the upper load limit.