In the forming experiment, the large aluminum hub is taken as the forming object, with a diameter of 660mm and a height of 212mm. Its structure is shown in the figure. The hub has the characteristics of complex shape, uneven wall thickness, high requirements for part size and surface accuracy. During the experiment, a kind of Al Cu cast aluminum alloy material with copper content between 4.5% and 5.5% was selected. In addition, it also contains Mn, Ti, B, re and other trace elements.
According to the analysis of this large part, three key technical parameters of molten liquid filling temperature, filling speed and specific pressure need to be determined. As for the parameters of specific pressure, since there is no recognized and exact expression in various theoretical analysis methods, this paper uses the empirical data of Al Cu material direct squeeze casting as the specific pressure parameters of the large aluminum wheel hub composite squeeze casting forming method, and finally calculates that the extrusion pressure of the hydraulic press should reach at least 1600t. At the same time, because the optimal filling temperature is mainly determined by experiments on specific materials, the empirical data of 720 ℃ is used as the filling temperature parameter for Al Cu materials.
For the filling speed parameters of the composite squeeze casting method, because the method requires the mold to be pre fitted, the filling speed can be simulated by using the numerical simulation software in the filling mode of indirect squeeze casting to obtain the optimal speed. The filling simulation of large-scale wheel hub shows that when the filling speed is less than 30mm/s, there is no turbulence and air entrainment during aluminum alloy melt filling, and the filling is stable, with high efficiency and small heat loss. Therefore, 25mm/s is used as the filling speed of the composite squeeze casting method for large-scale aluminum wheel hub.