Development Of High Pressure Injection Module For Normal Hydraulic Injection Molding Machine

In recent years, with the rapid development of plastic industry, the development of injection molding machine is with each passing day. In order to improve product performance, reduce the loss of energy sources, meet specific application requirements, more and more scholars began to study how to improve the injection molding machine and the process. Research shows that increasing injection pressure can improve the precision of the product, reduce shrinkage and enhance products mechanical properties. However, at present, the injection pressure of the common hydraulic injection molding machine is relatively low and unable to meet the requirements of high pressure injection. In order to solve this problem, something was studied in this paper.First of all, different forms of pressurization were studied to analyze the pressurization effect of different forms. And that which method can realize modularization was researched. The injection pressure was promoted by the way of series hydraulic cylinder according to the result of the analyzing. According to the request of the action in the working process of hydraulic cylinder, the hydraulic circuit was designed. The protection device was designed by the unloading valve and travel switch to ensure the injection molding machine can run safe after pressurization.Secondly, the relationship between the system oil pressure and the injection pressure was demonstrated. The largest injection pressure was identified as 320MPa after charging by the restrictions on the size of the clamping force and the goal of the design. The maximum injection pressure compared with before was increased by 56.86%. Different ways of power transmission were studied, the scheme connecting two piston rods through the screw thread was identified and the depth and dimension of the screw thread were analyzed and determined. The key components of hydraulic system, especially large force parts, were analyzed and checked. The hydraulic system of the injection molding machine was disassembled and the improvement of the hydraulic system of injection molding machine was completed.Thirdly, the mold blocks were designed according to the size of the impact and tensile spline. The gate, channel, exhaust system and temperature control mode were determined. The relationship between the deformation of the mold plate and the critical value of material overflow was analyzed and compared.Finally, in order to verify the improved effect of the injection molding machine, the injection test was completed by using PP and ABS. The test results show that the maximum.injection pressure of the injection molding machine was improved from 204MPa to 320MPa and the lack of material, air bubble, sag of the product were gradually being weakened until finally disappeared with the increase of injection pressure. The tensile strength of the tensile spline produced by ABS and PP using pressurized module was increased by 7.2% and 3.0%, compared to the original. The weight of the tensile and impact spline produced by ABS using pressurized module was improved by 5.4% and 3.6%. The weight of the tensile and impact spline produced by PP using pressurized module was improved by3.8% and 2.4%. The shrink mark in the height direction of the spline produced by ABS and PP using pressurized module was reduced by 9.5% and 6.8%. The impact strength of the impact spline produced by ABS and PP using pressurized module decreased by 22.0% and 16.0%.