Research on Key Technologies and Applications of Hollow Blow Molding Product Billet Forming
Extrusion blow molding is the primary method for processing and shaping hollow blow molded products. The quality of the billet during the molding process will directly affect the accuracy, function, processing cycle, and cost of the product. Therefore, how to ensure the quality of the billet has become the core issue in the extrusion blow molding process. The extruder head is an important component in the molding of preforms. The traditional "Try and Error" planning method has a long cycle and high cost, and if the wall thickness is not controlled during the molding process, it can easily lead to uneven axial wall thickness and material waste in the final product.
Therefore, this article mainly discusses the technology of ensuring the quality of the billet from two aspects: the planning of the machine head and the completion of the control system. In terms of machine head planning, modern advanced CAD/CAE technology is applied to the internal flow channel planning of the machine head. The method of numerical simulation of the extrusion process of the machine head is mainly studied, including the construction of a mathematical model composed of control equations, constitutive equations, initial values, and boundary conditions, and the derivation of the finite element solution method for the mathematical model. Based on the aforementioned principles, a finite element simulation analysis was conducted on the extrusion process of the 5L double-layer bottle blowing machine composite head, and the dispersion rules of the flow field in each part of the head channel were obtained. The extrusion function of the head was evaluated based on the uniformity of the inlet pressure and outlet velocity of the head, the dispersion of high viscosity areas, and the stability of the co extrusion area interface. According to the criteria of improving the uniformity of the melt outlet velocity and preventing viscosity phenomena, the internal and external head channel structures were optimized, and the results showed significant effects after optimization. And further analyze the influence of molding process parameters represented by material non Newtonian index, inlet flow rate, and inlet volume flow rate ratio between inner and outer layers on the extrusion function of the machine head, which has certain practical guidance significance for formulating extrusion process parameters of the machine head.
