Optimization Of The Electric-mechanical Toggle Clamping Mechanism With Negative Angel On Electric Injection Molding Machine

Currently electric-mechanical clamping mechanism is the most commonly used mechanical structure on all-electric injection molding machine, and it is one of the important components of precision injection molding machine, the platen opening and closing movements, mold locking and ejector pushing function are all driven by motor. Electric-mechanical clamping mechanism has a direct impact on the accuracy of the plastic products, excellent capabilities of kinematics and mechanics, and high stiffness of the system are important conditions for precise injection molding technology. A comprehensive optimization for the clamping mechanism would be benefit to improve the clamping capacity and market competitiveness of the injection molding machine.This paper made an introduction of the development situation on electric injection molding machine, then it described the structural composition of the electric-mechanical clamping mechanism, and it introduced the characteristics of toggle clamping mechanism with a negative angel. Based on the working principle and theoretical calculation methods of the toggle mechanism, it deduced the mathematical expressions of kinematics and mechanics characteristics for the negative angel toggle structure, including parameter such as velocity ratio, stroke ratio, force magnification and system stiffness, also it provided a theoretical basis for the optimization of the clamping mechanism and deformation of the toggle parts. The optimization of the toggle clamping mechanism was done from three aspects.Firstly, combined the theory calculation of the kinematics parameters, it built the optimal model for the toggle mechanism, and using MATLAB software and two optimal methods to operate the optimization, that made improvements of the kinematics capacity. Then it built graphical interface to make optimization more convenient, and verified the result of the optimization by experiment. It provided a viable method and process for the negative angel toggle mechanism.Secondly, combined the theory calculation of the mechanics parameters, it discussed the relationship between stress cross-section of toggle part and system stiffness, and using ANSYS Workbench software to make finite element analysis for the assembly with toggle part. Then it reduced the deformation of the toggle part as to increase system stiffness, by improving the cross-section structure on the key position of the toggle part.Thirdly, it proposed the improved models of the stationary platen and mold adjusting platen, and using Hypermesh software to operate the structure topology optimization of the models. That process made the improved models lose weight, so it got good platen models with structure improving and weight losing after the topology optimization. It provided a reference method for improving the platen structure.