Study On The Key Techniques Of Blow Molding

Blow molding is the technology that produces parison with the use of extrusion or injection molding machine at first, and then sends the hot parison into the blow mold, closes the mold and clamps the parison at the same time ,after that, blows the hot parison onto the cold die wall, at last ejects the products after cooling. The processing includes three steps: (1) Melt plastification. Melting the raw material with the use of extruder and injection machine; (2) Parison molding. Molding the parison with the use of extruding die and mouth mold or injection mold; (3) Blow molding. Providing compressed air with the use of auxiliary air compressor and clamping the mold to process the products with the use of hydraulic clamp equipment. The strong points of blow molding are: (1) The cost of mold and die is low; (2) Having the capacity of injection molding complex hollow articles; (3) Having the capacity of producing massive articles. The three major methods of blow molding are: extrusion blow molding,injection blow molding and stretch blow molding. Blow molding is only applicable to the thermoplastic plastics, for example, PE,PVC,PET and engineering plastics for example makrolan etc. The main study results are summarized as follows:1. 3D blow molding technologyThe most important novel development in recent years is the 3D blow molding technology, and also called less waste or no flash hollow blow molding. In the traditional extrusion blow molding, the parison enters into the mold vertically, and the motion track is straight line. In the 3D blow molding, the parison orientates in the opened or closed mold, and it's operated in the mold cavity. The products molded in this way have complex geometrical shape, and meet the demand of complex and flexuous transport pipes, which makes the technology development. Compared the the traditional technology, the advantages of 3D blow molding are as follows: (1) the demand of mold clamping force is low; (2) the workload of cutting excessive material is low; (3) it's not necessary to re-trim the external diameter of the products; (4) the quality of the products is raised, because of the wall thickness distribution design, and it doesn't reduce the die strength; (5) because of the reduce of the leftover material, the necessary reclaimed material is reduced, and it makes the probability of the degradation of the temperature-sensitive material become lower, and we can use smaller extruder at the same time. 3D blow molding can be divided into X-Y processing, negative pressure blow molding and arc blow molding, based on the supplied technics and equipments. In this paper, we introduced the application of the blow molding in the automotive components. With the development of the automobile lightweight, more and more automotive components is produced by blow molding, for example, more and more pipes used on the automobile with complex shape are molded by blow molding technology. Moreover, we also study the technological conditions of blow molding. It's necessary to control the parison temperature, blow pressure, blow speed, cooling time and mold temperature. In order to make the thickness well-distributed, we can use the thickness control program to regulate the parison thickness.2. The numerical simulation of steering wheelIn this paper, we take numerical simulation of the steering wheel, and get the fusion analysis, and inspect some technological parameters such as injection shot, delay time, melt temperature, gas pressure, and their influence on the gas penetration. According the simulation results we find the optimization processing technological conditions and the inflation plans.3. Design of the blow molding product and mouldWe studied the design of the blow molding product and mould. when design the blow molding product, under the premise of ensuring the practicability (such as dimensional accuracy, mechanical strength, shape, chemical properties, electrical properties, etc.), we must make the structure easy, wall thickness even, use convenient, and mainly studied the compute method and influencing factor of shrinkage factor, and the structure in order to obtain product with even wall thickness and better mechanical property. In the design of blow molding mould, we mainly studied the cooling system, cut billet port, and exhaust air system. They have a great impact on the surface quality and the mechanical properties of products.