Press with control circuit arrangement

摘要

A press (2) having a three phase, brushless, direct current drive motor (26) driving a press ram (22) by a way of an eccentric shaft (78) is provided with a control circuit arrangement (89) comprising an incremental encoder (30) for measuring the angular position of the drive shaft (78), and Hall effect sensors (94) for continuously measuring the speed of the drive motor (26). The control circuit arrangement (89) also comprises a computer (108) having registered therein a desired motor speed program (112), and a motor control circuit (104) for comparing the outputs of the encoder (30) and the sensors (94) with the program (112) and feeding the result of the comparison to a motor drive pulse generator (96) to control the speed of the motor (26) in accordance with the program (112) and to stop motor (26) upon the press ram (22) reaching a position at least proximate to its home position (0 DEG ) at the end of a cycle thereof.