Patent ID: 8047131

Claim:
A control apparatus of a press machine, the press machine comprising: (a) a motor; (b) a converting mechanism having a rotating body rotationally driven by the motor and converting a rotational motion into a reciprocating motion; (c) a slide coupled to the converting mechanism and reciprocating a motor performance torque that is fluctuated in accordance with a rotational angle of the rotating body when rotating the motor at a fixed instruction speed; and (d) the control apparatus comprising i. an angle detecting apparatus disposed to detect a rotational angle of the rotating body; ii. a torque determining apparatus disposed to determine a necessary motor torque in correspondence to a characteristic of the press machine on a basis of a value of the rotational angle input from the angle detecting apparatus; and iii. a speed adjusting apparatus increasing the rotational instruction speed of the motor to a value more than the fixed instruction speed, at the rotational angle of the rotating body in which the necessary motor torque becomes smaller than a predetermined motor torque reference value, wherein the predetermined motor torque reference value is an average value over one cycle of the fluctuating necessary torque, or an average value of the necessary motor torque over a predetermined time, or a fixed value that is larger than a minimum value of the necessary motor torque and smaller than a maximum value of the necessary motor torque.