Study On The Constant Energy Consumption Plasticizing And The Low Pressure Injection Molding Process

In recent years,As the main production technology of plastic products,injection molding has been widely used in many industries.As the users’requests of dimensional accuracy and color uniformity of plastic products gradually increase,The traditional injection molding technology shows some limitations:In the plasticizing stage of injection molding machine,the axial retreating of screw causes the difference of melt thermal and mechanical process,which results in uneven melt temperature distribution and affects the color uniformity and residual stress distribution of the product eventually.And in the injection stage of the injection molding machine,the increase of the frozen layer thickness in the runner causes the melt pressure loss to become larger,leading to high injection pressure,increasing the cost of equipment and energy consumption.The above characteristics limit the application range of injection molding process,and seriously affect the green and precision development of the process.In the plasticizing process of the reciprocating periodic injection screw,the melt’s thermal and mechanical history is different and the temperature is not uniform due to the screw retreat.In this paper,a control method of uniform plasticizing with equal energy consumption is proposed.Based on the theory of screw plasticizing energy consumption,the energy consumption model of injection molding machine in plasticizing process was established,and the governing equation of screw rotating speed varying with displacement in plasticizing process was obtained to ensure the temperature uniformity of melt.The experimental results show that this control method can effectively improve the melt temperature uniformity and improve the weight repetition accuracy of injection products by more than 30%.With this method,the plasticizing quality of the melt can be ensured by setting the screw speed in sections without any modification of the equipment,which provides a practical solution for improving the plasticizing quality.In order to solve the problems of unbalanced filling and high injection pressure in the traditional injection molding process.In this paper,the lowpressure injection molding process was studied,and the filling mechanism and application range were numerically simulated by using Moldex3D software.The simulation results show that the low pressure injection can reduce the melt flow rate gradually by keeping the melt pressure constant at the inlet,which can effectively improve the unbalance of multi-cavity mold filling caused by shearing heat generation;And for common products(flow length ratio less than 200),using low pressure injection method can reduce the injection pressure by more than 20%.In addition,this topic combined with the Taguchi experimental design method,the goggles product process parameter combination for optimization design.It reveals the law of the influence of low pressure injection process parameters on the properties of products,The maximum warpage of the lens is reduced by 29.6%and the optical birefringence is reduced by 63.3%,which effectively optimizes the mechanical and optical properties of the goggles.The low pressure injection molding technology can effectively reduce the pressure required for product molding,reduce the equipment requirements and energy consumption,and improve the situation of high defective rate and unstable product performance caused by unbalanced filling of multicavity mold.