# Measurement results of interface pressure in Squeeze Casting

In the study, working conditions 1, 2, 3 and 4 represent four working conditions with applied pressure of 70, 46, 23 and 0mpa. Three to four experiments were carried out under each working condition, and the maximum error of temperature and pressure measured by different experiments was less than 4%. The initial mold temperature of condition 1 is 230 ℃, the initial mold temperature of other three conditions is 250 ℃, and the pouring temperature of four conditions is 660 ℃.

The typical curves of the casting die interface pressure measured at position 2 in conditions 1, 2 and 3 are shown in Figure 1. Position 2 is in the center of the casting.

As shown in Figure 1, the time of pressure application is marked as O. At this time, the punch acts on the casting, and the applied pressure is completely applied to the casting. The interface pressure between casting and die increases to the maximum value at the moment when the applied pressure is applied. The maximum values of the interface pressure in conditions 1, 2 and 3 are 41.1, 27.1 and 13.4 MPa respectively. The ratio of pressure loss is almost the same under all working conditions, which is 41%. The main reasons for this phenomenon are as follows: on the one hand, there is friction resistance between the cavity wall and the punch surface, which has a greater obstacle to the pressure transmission; on the other hand, the external pressure is applied to the casting after pouring for a period of time, at this time, a certain solidified shell has been formed, and the deformation resistance of solidified shell is also an important reason for the pressure loss.

The typical curves of the casting die interface pressure measured at position 2 in conditions 1, 2 and 3 are shown in Figure 1. Position 2 is in the center of the casting.

As shown in Figure 1, the time of pressure application is marked as O. At this time, the punch acts on the casting, and the applied pressure is completely applied to the casting. The interface pressure between casting and die increases to the maximum value at the moment when the applied pressure is applied. The maximum values of the interface pressure in conditions 1, 2 and 3 are 41.1, 27.1 and 13.4 MPa respectively. The ratio of pressure loss is almost the same under all working conditions, which is 41%. The main reasons for this phenomenon are as follows: on the one hand, there is friction resistance between the cavity wall and the punch surface, which has a greater obstacle to the pressure transmission; on the other hand, the external pressure is applied to the casting after pouring for a period of time, at this time, a certain solidified shell has been formed, and the deformation resistance of solidified shell is also an important reason for the pressure loss.

When the interface pressure between casting and die reaches the maximum value, it decreases gradually. Under all conditions, the reduction rate of interface pressure is basically the same, which is 2.46mpa/s. As shown in Fig. 1, the decrease law of interface pressure is shown in KP, LQ and MT sections. In addition, it can be found that there are regular fluctuations in the pressure reduction stage, which is caused by the pressure compensation process of the press. When the press is in the pressure maintaining state, the pressure relief always exists. When the pressure is lower than the set value, the press will automatically compensate for the pressure loss. In the process of pressure measurement, such small fluctuations can be accurately measured, so the accuracy of pressure measurement is quite good. According to the results of temperature measurement, these small pressure fluctuations have no effect on the heat transfer of the casting die interface.

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