| Plastics are becoming more and more demanding.Injection molding system is becoming precision,high efficiency,intelligent,lightweight and energy-saving.Injection molding machine gradually from universal to special aircraft.Injection molding machines need to be immediately customized and optimized for a variety of application scenarios.The upgrading of toggle clamping unit ensures the smooth implementation of modernization and upgrading process of injection molding machine.Toggle type clamping unit has excellent motion characteristics.It is widely used in all kinds of injection molding machines,and it is urgent to comprehensively optimize its performance.This study focused on multi-objective optimization of toggle type clamping unit of 260 T injection molding machine,and carried out the following studies:In the aspect of theoretical analysis,the model compatibility of toggle clamping unit is analyzed in principle.This provides a theoretical basis for calculating the performance objective function of toggle mechanism.In the same coordinate system,the mathematical function expressions of the structural parameters,its motion characteristics,mechanical characteristics and locking model characteristics are derived.Based on the innovative design theory of mechanical structure,the configuration of the double-toggle five-point internaloverturning inclined row clamping unit was studied.The structural advantages and disadvantages of the current toggle mechanism were summarized,and the potential optimization of the current mechanism was put forward.In terms of structural parameter analysis of toggle type clamping system,the variation rule of each performance evaluation index under the independent influence of single structural parameter of toggle clamping unit is summarized.The 3D model and virtual prototype of toggle clamping unit of 260 T injection molding machine were established.The motion characteristics of virtual prototype are analyzed and verified.The sensitivity of a single structural parameter to the motion characteristics of the moving template was investigated.In Matlab,the functional relationship between the structure parameters of toggle mechanism and stroke amplification ratio and force amplification ratio is used.The reasonable value range of each structure parameter is obtained.It provides effective guidance for setting the value interval of independent variable in the process of performance multi-objective optimization.In the aspect of multi-objective optimization of toggle clamping unit performance,the performance requirements under different application scenarios are summarized.The comprehensive performance improvement problem of toggle clamping unit is transformed into multi-objective optimization problem.The intelligent multi-objective optimization algorithm NSGA-Ⅱ was applied to the performance optimization of toggle clamping unit of injection molding machine,and a new optimized scheme was obtained.The changes of stroke amplification ratio,force amplification ratio and displacement,velocity and acceleration response of the dynamic template were compared before and after optimization.The amplification ratio of force increased by about 30% with almost no deterioration of other performance indexes.Based on the case of 260 T injection molding machine clamping unit performance optimization,a software platform for its performance evaluation and multi-objective optimization was established.The relationship between structure parameters and performance of clamping unit is simulated.Users can select the optimization scheme according to their needs and set the optimization interval to complete the multi-objective performance optimization calculation.A series of optimization schemes provided by Pareto frontiers can be obtained.It provides a practical tool for the design of toggle type die closing mechanism of injection molding machine. |
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