A variable input speed approach for improving the output motion characteristics of Watt-type presses

Traditionally, the input speed of a Watt-type press is assumed constant. Here, we propose a novel approach by varying the input speed of the crank to make the ram's motion suitable for both deep-drawing and precision-cutting processes. This approach uses a servomotor as the power input of the mechanism. By properly designing the input speed, the output motion can pass through a desired trajectory. The input motion characteristics are planned with Bezier curves. Optimization is used to improve the output characteristics of the system. Guidelines for defining the optimization problems are discussed, and control algorithm regarding how this servo system works is described. Two design examples, Watt-type press and knuckle joint press, are given for illustration. (C) 2000 Elsevier Science Ltd. All rights reserved.