Before starting production, the blank should be heated and moistened, and the light dies holder and cavity should also be preheated. Usually, preheat to 150 ~ 300℃ before light pressure manufacturing. The key to preheating the Table Mould is to ensure that:
(1) the temperature of the lightly pressed blank is not reduced too fast when the lightly pressed blank is put into a table mould to prevent the ductility from being reduced and the deformation resistance from being improved; The temperature difference between the surface layer of the blank and the management layer is prevented from being too large together, so as to avoid defects or damage of the table mould caused by light pressing parts due to uneven deformation.
(2) Reduce the temperature difference between the table mould and the blank, and prevent the table mould from being damaged due to excessive internal temperature difference caused by the rapid rise of the surface temperature of the table mould.
The specific method of preheating the table mould is to install a professional internal resistance preheater on the mould or to preheat it with a blowtorch or by placing red-hot iron blocks on the mould. The preheating temperature depends on the temperature of the lightly pressed blank.
During the continuous production process of the table mould, because of long-term contact with the blank with higher temperature than itself, the temperature of the convex and cavity will continue to rise and the strength will drop sharply, thus endangering the service life of the table mould. At the same time, under the effect of high light pressure shearing force, the mould after temperature rise is easy to deform, thus seriously affecting the appearance and specification precision of light pressure parts. Therefore, in the mould structure, it should be considered to set cooling equipment or continuously choose artificial cooling method to keep the table mould temperature in the range of 150 ~ 300℃.
