Study On The Precision Molding Of Polymer Composites Tank Head

In recent years, the development of polymer materials promotes the expansion of material application fields, polymer composites tank is gradually accepted in practical applications and popularized in special areas. For a long time, the lower thread dimension accuracy of domestic tank head seriously affects the overall quality and performance of polymer composites tanks. Due to the higher dimension accuracy requirements of tank head thread this local structure, it does not meet the requirements that adopting conventional injection method designs product structure, gating system and process parameters; simultaneously, the subsequent process also has an influence on the thread dimension, this makes the precision control of the head more difficult. Therefore, how to ensure the precision molding of polymer composites tank head has become a problem that needs urgent solution in improving such tanks overall quality. In this paper, the dimension detection and reverse configuration is carried out on the head thread, the results show that injection molding is the main process which affects the thread dimension accuracy of current products. In this paper, the Moldex3D professional analysis software is used to optimize the product structure, gating system and process parameters of the 2.5 inches tank head, so as to improve the dimension accuracy of head thread. On this basis, the pre-distortion correction design is carry out on the thread diameter dimension of the head mold cavity, and conducts injection molding experiments, the results show that the tank head after optimization meet the requirement. Details are as follows:First, carrying on tracking measurements for the head thread dimension in the whole production process of polymer composites tank, and conducting measurement match before and after the thermal process which is similar to the blow molding process on the head obtained by injection molding, finding that injection molding is the main process which affects the thread dimension accuracy of current products. On this basis, the thread shape is found changed through reverse configuration, and the diameter dimension is varied in the axial direction.For the precision injection molding of the 2.5 inches tank head thread, the Moldex3D professional analysis software is used to analyze the injection molding process, extracting the axial diameter dimension distribution of the molded thread to ensure the head thread precision. First, improving the head structure design, reducing the wall thickness of main body circular ring in order to improve the overall thickness uniformity of the head, the results show that this method can improve the dimension accuracy of the head thread. Then, improving the gating system design, the results indicate the intermediate plate pouring way can improve the axial uniformity of the thread middle diameter dimension, and increasing the number of gates can improve the circumferential deformation uniformity of the thread middle diameter.To study the effect of process parameters on the head and its thread dimension accuracy, the orthogonal analysis method is used to find the influence level of various process parameters on the thread dimension accuracy; and on the basis of the orthogonal analysis, the single-factor method is used to further optimize the molding conditions.Finally, on the basis of the design of tank head structure, gating system and process optimization, the pre-distortion correction method is used to design the thread diameter dimension in the mold cavity. And the thread accuracy of the tank head obtained by the mold meet requirements. However, the thread dimension of partial certified injection head is no longer meet the accuracy requirements after the tank blow molding process. For this, the blow molding process is analyzed, it is found that the wall thickness of tank head main body circular ring is a key factor to influence the head thread dimension in blow molding process, this indicates that improving the dimension accuracy of the head thread must consider many factors involved in polymer composites tank molding.