The so-called pressure casting mainly refers to the aluminum alloy wheel hub casting obtained by filling the liquid metal into the mold cavity at a high speed under the action of high pressure and condensation through the action of pressure. The aluminum alloy wheel hub casting produced by pressurehas the advantages of strong mechanical properties and compact structure, and has high strength and hardness. However, the biggest defect of aluminum wheel hub under the traditional pressure casting process is that heat treatment can not be used to improve the performance. The main reason is that the liquid metal stamping speed is relatively fast, and the gas in the mold cavity can not be eliminated, resulting in the storage in the form of pores in aluminum alloy wheel hub castings, which can expand through heat treatment, This leads to bubbles in aluminum alloy hub castings.
In recent years, non porous die casting technology has emerged, in which “oxygen filled die casting” is the main representative. Oxygen filled pressure casting method is mainly to promote the replacement of liquid metal and air in the pressure chamber, and carry out pressure casting under the condition of high pressure and high speed. When the liquid metal is filled, the oxygen will be discharged through the exhaust slot on one side, and the aluminum liquid and oxygen will react on the other side, so as to form alumina particles, which are distributed in all parts of the aluminum alloy wheel hub casting, so as to prevent air holes in the aluminum alloy wheel hub casting. Compared with the traditional pressure casting method, the oxygen filled pressure casting method has six characteristics:
① Reduce and eliminate the porosity of Aluminum Alloy Hub Castings, so as to improve the density of Aluminum Alloy Hub Castings;
② Compared with ordinary castings, the strength of oxygen filled pressure castings can be increased by 100% and the elongation can reach 50%;
③ Heat treatment is carried out for oxygen filled pressure castings to improve the mechanical properties, so as to ensure that after heat treatment, the strength can be increased by 30%, the elongation can reach 100%, and the impact toughness and yield limit will be significantly improved;
④ The oxygen filled pressure casting can work at 300 ℃;
⑤ Oxygen filled pressure casting can burn a small amount of alloy components;
⑥ For oxygenated pressure casting, devices for controlling oxygenation should be added. In the process of oxygenation, not only oxygen can be consumed, but also the cycle time of pressure casting can be increased, which leads to the cost of oxygenated pressurebeing 15% higher than that of ordinary pressure casting parts. Using oxygenated pressure casting can improve the yield, strictly control the quality and control the production cost.