Direct squeeze casting is used in squeeze casting experiment. The die used in squeeze casting experiment is shown in Fig. 2 and Fig. 3, and the die material is H13 steel. In the process of direct squeeze casting, the high temperature melt is poured into the mold, and then the punch is pressed down, and the punch acts directly on the whole casting. It takes about 4-5s from the time when the punch is pressed down to the time when it completely acts on the casting.
In the actual squeeze casting production process, due to the complex part shape and different process parameters, the heat transfer coefficient and interface pressure of the casting die interface change with time and space. In order to better understand the heat transfer behavior of the casting die interface and the variation of the interface pressure, the plate casting was used as the research object in squeeze casting experiment. The thickness of the plate casting is much smaller than its width and length, so the internal heat transfer of the plate casting can be approximately assumed as one-dimensional heat transfer, which is the premise of the inverse algorithm; for the parts with complex structure, the heat transfer of the interface between the part and the mold can be approximately considered to be composed of many small one-dimensional heat transfer units, so the plate casting is a very representative research field Research object. In addition, the simple shape makes the pressure transfer path very simple. During the experiment, the variation of the pressure at the casting die interface under different conditions can be obtained by adjusting the applied pressure and process parameters; and the influence of the thickness of the casting on the pressure transfer and interface heat transfer can be studied by adjusting the pouring amount. As shown in Fig. 1, the size of plate casting is 140mm × 90mm × 30mm.
In order to accurately measure the internal temperature and interface pressure of the die, three temperature measuring units (ts1-ts3) and three pressure sensors (pt1-pt3) are installed in the lower die of squeeze casting die. Their arrangement is shown in Fig. 1 and 2. The pressure sensor and the temperature measuring unit are symmetrically arranged, so it can be approximately assumed that they measure the interface pressure and the internal temperature of the die at the same position. In addition, the end faces of each pressure sensor and temperature measuring unit are flush with the bottom surface of the die cavity to ensure accurate pressure and heat transfer coefficient of the casting die interface.