| 摘要 |
The invention provides an automatic die changing system for a power press with at least one carrier for transporting dies to and from a selected location in the press. The carrier is supported on a set of wheels, which are driven by at least one AC induction motor. An adjustable frequency AC motor drive supplies an AC frequency and voltage to the AC induction motor to control the speed of the motor and therefore the speed of a horizontal movement of the carrier into or out of the press. The speed of the carrier may be rapidly increased by increasing the AC frequency supplied to the motor on the individual wheels. A proximity detector signals the motor drive to trip a dynamic braking resistor, which electronically changes the phase order of the motors to reverse the direction of motor rotation, to decelerate the carrier in order to locate the carrier in the proper position. |
