Optimal design on Watt-chain double-toggle mold clamping mechanism for injection molding machine.

Introduction: The mode clamping mechanism is the most important part of forming section for the plastic injection molding machine. If this mechanism has double-toggle effects at the close position, it will get a larger clamping force and have higher safety. This study focuses on the optimal design of the Watt-chain mechanism with double-toggle effects at the close position.

Methods: The Watt-chain double-toggle mechanism is chosen to be the mold clamping mechanism by referring to the existing patents. Then, the kinematic characteristics of the Watt-chain double-toggle mechanism are analyzed by the vector loop method. Finally, based on the kinematic requirements and the proposed optimal design process according to the objective function, the optimal design on Watt-chain double-toggle mechanism is accomplished in this study.

Results: This study proposes an optimal design process on Watt-chain double-toggle mold clamping mechanism. By following the optimal design process, the optimal Watt-chain double-toggle mold clamping mechanism has a maximum acceleration 3418 mm/s ( = 3418 mm/s) and a force ratio is 2.24 (/ = 2.24).

Discussion: According to the studies on the optimal designs of mechanisms, the optimal Watt-chain double-toggle mechanism, which is better than the multiple-joint double-toggle mold clamping mechanism in the existing patent by reducing 19.5% of acceleration and 30% of a driving force, is proposed. The results of this study could be the design reference in engineering when designing mold clamping mechanisms for plastic injection molding machines.