Study On Optimization Design Of Double Toggle Clamping Unit Of Injeciton Molding Machine

Clamping Apparatus is one of the important components of Injection Molding Machine, it's used to close the mold reliably and propel the closing or opening movement and push the mold products out. The system rigidity, the clamping force and the clamping speed of Clamping unit not only effect on the quality of molding products, but also determine the cyclic number and the total energy consumption of the machine, in addition, the structure of Clamping unit also impact the cost of the machine. For Toggle Clamping Unit, the larger force amplification and the larger stroke ratio can reduce energy consumption and improve the productive efficiency. However, if the traditional structural design which rely on mapping, diagrams, analogies, experiences is used, because of too many design variables, the design work is too much, the design period is too long, the structural parameters cannot achieve the best match, the force amplification and the stroke ratio cannot meet performance requirements, which reduce the performance and practical value of Clamping Unit.As a new design method Virtual Prototyping Technology is widely used in the design and the study of Mechanical production systems. It can not only reduce the design period to decrease the cost of research, but also simplify the process of mechanical product design and improve the performance of products. Eventually, the optimized products are the best ones.In this article, double-toggle clamping unit of small SZ400 injection molding machine produced in Fenxi Heavy Industry is the research object. Analysis of motional and mechanical characteristics for the double-toggle clamping unit is made systematically, and the formulas which include the geometry and position of the elbow-bar, the mold board stroke, the speed, the force amplification is deduced. Stroke ratio and force amplification are selected as the objective function, and also appropriate design variables and constraints are determined, finally, the mathematical model is established.Using virtual prototyping technology, the five hinge joint-double clamping unit parametric model is established objectively, the model's dynamics simulation analysis is carried out to obtain the kinematics and dynamics characteristic curve, and the sensitivity of points which reflect the geometry and position of the elbow-bar is analyzed, then the optimal design of points can be accomplished. That is, on the requirements of size constraints and performance constraints, the best design project of structural parameters is obtained.In view of the performance and economy of clamping unit and using the efficacy coefficient method to assess the optimized result, the conclusions are as following:the force amplification increase 6.1% when it is treated as optimization objective, the larger force amplification reduces the clamping energy consumption and the shock of clamping systems and improves the quality of products; the stroke ratio increase 5.9% when it is treated as optimization objective, the larger stoke ratio improves the speed of clamping, productive efficiency and compact structure. The optimized results shows that the optimum proposal can meet requirements of the motion and force performance as well as in the original plan, and also can meet the user's other demands such as compact structure, etc.The study of this paper provides theoretical models and optimized methods for optimization design of double-toggle clamping unit.