Abstract: A crank press includes an encoder measuring an angle value of a servo motor, a strain detector module generating a converted load value associated with deformation of a machine body, a memory storing at least one relation between an angle value and each of an upper torsion limit and an upper load limit, and a controller calculating a torque command value based on a position command, reading the upper torsion limit corresponding to the measured angle value, determining whether the torque command value exceeds the upper torsion limit, outputting the torque command value when negative, and outputting the upper torsion limit when affirmative. The controller further stops the servo motor when the converted load value exceeds the upper load limit corresponding to the measured angle value.

Abstract: A crank press includes an encoder measuring an angle value of a servo motor, a strain detector module generating a converted load value associated with deformation of a machine body, a memory storing at least one relation between an angle value and each of an upper torsion limit and an upper load limit, and a controller calculating a torque command value based on a position command, reading the upper torsion limit corresponding to the measured angle value, determining whether the torque command value exceeds the upper torsion limit, outputting the torque command value when negative, and outputting the upper torsion limit when affirmative. The controller further stops the servo motor when the converted load value exceeds the upper load limit corresponding to the measured angle value.