Study On Composite Squeeze Casting System For Large Parts

Squeeze casting process is characterized by molten metal being crystallized under highpressure, resulting shrinkage reduction, excellent mechanical properties, and can achieve"near net shape". With the rapid development of manufacturing industry, especially in theautomotive and aerospace, the needs and demands of large parts increase dramtically. Theperformance and the defects improvement of the cast for squeeze casting attract more andmore attention in market. Due to the limitation of squeeze pressure of the equipments inChina, little research for large parts of the squeeze casting was held. Therefore, carrying outthe research on forming method and forming system of squeeze casting for large parts makesa certain sense. This paper undertook a series of studies on forming method, design theory,simulation analysis, testing technology and experimental research for forming system ofsqueeze casting technology.Firstly, technical features of direct and indirect squeeze casting and problems in themanufacturing of large parts were analysed. On this basis, forming method of compositesqueeze casting was developed. Acorrding to the futures of molten metal being transferred inan enclosed space and mold being pre-closed, an overall design of the composite squeezecasting devices were conducted. Then the forming system of composite squeeze casting wasestablished using composite squeese casting devices as the prototype, and follow-up studiesof technical route was determined.Furthermore, acorrding to the futures of delivering large volume of molten metal, longdistance of delivery route, complexity of system and high requirement of thermal control, anew delivery system was designed. The system comprises pneumatic drive unit, infusiontubing and corresponding control software and hardware. The delivery system for moltenmetal is designed in detail, including establishing thermal control model of infusion pipetubing, determining the parameters of thermal control. The test results show that the problemsof delivering large volume of molten metal for squeeze casting were solved well.Then, according to the special requirements for large parts of the composite squeezecasting, a rigid support floating mold was designed and manufactured. This mold can achievepre-closing and accurate quantitative filling. The simulation of floating mold structure wascarried out during the mold design process, and the simulation results show that the mold,either in weight or in the case of driving pressure, can work smoothly, which verified themold can meet the requirements of composited squeeze casting for large parts. The established composite squeeze casting system for large parts provides the basis forthe simulation of production logistics system. The timing relationship of composite squeezecasting devices and the idle rate of these devices was simulated and analysed for roductionlogistics system. Technical approach of productivity improvement method and equipmentutilization rate was explored, which helps to further improve the system of composite squeezecasting for large parts.Finally, according to the design, a composite squeeze casting system was manufacturedand forming ability of the system was researched by produce large-scale wheel hub usingAl-Cu material. Test results show that the squeeze pressure of composite squeeze casting canbe built up very quickly, which helps to improve the quality of castings. Giving full play tothe floating rigid support mold characteristics, the requirement of quantitative filling wasguaranteed, which verified the feasibility, effectiveness and practicality of the compositesqueeze casting system for large parts.