Investigation On Mechanism And Equipment Design Of Vibration-squeeze Casting For Aluminum Alloy

Aluminum alloys are widely used in the automotive and aerospace because of their merits including low density, high specific strength, good heat conductivity, etc. And as a kind of traditional metal thermal processing, casting has many advantages compared with other forming processes, it has been widely used in the manufacturing such as machine tools, automobiles, tractors, motive power machine, etc. due to its low production cost, high material utilization and resource conservation. Therefore, the continuous refinement and optimization of alloy casting process is of importance for manufacturing. This paper proposed a method of Aluminum alloy vibration-squeeze casting method, which is the consideration and summary of the traditional foundry method, in order to take better advantage of the superiority of vibration and squeeze in Aluminum alloy casting. Vibration is composited in squeeze casting, which turns static squeezing into dynamic squeezing and a vibrational field formed in the liquid at the same time. It has stronger practicability by directly pass vibration into Aluminum alloy rather than put the whole casting equipment on a vibration table.In this paper, the forming principle of vibration-squeeze casting method was explained and the mechanism of feeding and broken crystal was analyzed. Theoretical analysis results show: the vibration-squeeze casting method can reduce casting shrinkage and porosity defects with the abilities in increasing the liquid’s gravitational acceleration and feeding power, breaking secondary dendrite and expending the feeding channel; At the same time, it can greatly increase the maximum normal stress and the maximum shear stress of the secondary dendrite, making it easier to be broken and to refine the grain size. On the other hand, the effect of vibrational impact on broken crystal has been strengthened in the process of vibration-squeeze.Experiment has been taken in this paper based on the theoretical analysis. An experimental setup was designed and its reliability was validated by numerical analysis. The corresponding experiment was carried out and the results are analyzed. The experimental results show: compared with gravity casting and squeeze casting, vibration-squeeze casting significantly improves the material utilization(the ideal utilization reaches 100%). In a reasonable time range, the longer the time of vibration-squeeze, the better the macro quality. In the aspect of feeding, vibration-squeeze casting has a better feeding effect on the alloy compared with gravity casting and squeeze casting. The macro and micro hole defects of vibration-squeeze casting was decreased obviously. In a reasonable time range, the longer the time of Vibration-Squeeze, the better the feeding effect. In addition, the effect of vibration on broken crystal is apparent. The secondary dendrite arm spacing was smaller and the casting mechanical properties were better than gravity casting and squeeze casting.According to the practical application of engineering, an equipment’s design method of vibration-squeeze casting was proposed in this paper based on die casting equipment. A working flow chart of the equipment was given as well. The overall design of the vibration-squeeze casting equipment was made and its key technical problems and corresponding solutions for different processes or different casting methods with the same process were analyzed. The assembly structure of the vibration-squeeze casting equipment was given and the core device, i.e., vibration-squeeze device, including its structure, process parameters and information system were designed and analyzed. The vibration-squeeze device can easily be controlled with parameters, such as vibration time, vibration frequency, vibratory force and vibration pressure. The vibration time, vibration frequency and vibration force were adjusted by a vibrator which was composed of two axes with a group of eccentric block. The transmission of axes which was driven by a speed regulating motor is carried out through a pair of gears. Vibration pressure was adjusted by two hydraulic cylinders.