Abstract:

A method for selecting the control parameters of the mold-temperature-control solidification (MTCS) is presented based on numerical simulations , and two significant parameters which are easy to control , are adopted to carry out the investigation. Then , a 3D transient heat transfer analysis is performed in various conditions with the mold-preheated temperatures of 743 , 693 and 673 K and the cooling thresholds of 753 , 293 and 673 K, and a deviance between the numerical and experimental data of less than 8% is obtained. The results indicate that (1) a mold-preheated temperature higher than the melting point of the workpiece contributes to the reduction of shrinkage cavities and the improvement offorming quality; (2) the mold-preheated temperature should be determined by considering both the molding efficiency and the process e盯or; and (3) at a cooling threshold of 753 K, all the cooling channels simultaneously open and obvious shrinkage cavities form in the upper center of the workpiece , while at a cooling threshold of 673 K, seven groups of cooling channels open in sequence and excellent forming quality is achieved since the solid-liquid interface maintains a near-planar surface and the solidification velocity remains fast.

Key words: mold, temperature control, solidification, control parameter, numerical simulation