Apparatus for cutting a plate into a predetermined size

Abstract

A cutting apparatus cuts a plate such as a corrugated cardboard or a steel plate into a predetermined size with a knife cylinder and includes a knife cylinder driver for controlling rotation speed of the knife cylinders by motors. The apparatus includes a speed compensator for producing a torque command signal so that there is no difference between a command rotating speed and a detected motor speed and a plurality of motor torque control device including a torque compensator for producing a motor command signal by proportional control so that there is no difference between the torque command signal from the speed compensator and a torque detecting signal, power amplifiers composed of transistors and which amplify the motor command signal from the torque compensator to produce a motor applied voltage and motors, particularly brushless motors controlled by the motor applied voltage from the power amplifiers, whereby transistor type power amplifiers having excellent response of speed can be used, the cutting accuracy and high speed cutting performance for the plate can be improved, and the proportional control is adopted to the torque compensator so that the dispersion of load to the motors is minimized.