Papers by Author: Jenő Dúl

Abstract: Quality of high pressure die castings is influenced by a lot of factors. Among them, the most important ones are the melt-, and die temperatures. This paper shows a data acquisition system, developed for measuring the melt and die temperatures and the results of the temperature measurements obtained under variable conditions. Evaluation of the relationship between the interrelated temperatures and the casting properties is based on analyzing the structure of the castings.

Abstract: The real system under consideration comprises of a solidifying casting with the casting mould, environment and other external influences. The process observed begins with the introduction of liquid metal to the channels of the runner system and filling of the mould cavity. This is connected with the contact of liquid metal with the atmosphere and also, with the walls of the mould. During the filling of the mould cavity heat transfer between the metal surface and the walls of the mould takes place (by radiation and conduction), which in practice can lead to mould cracking, and next to the formation of casting surface defects. In this stage of the process of great significance are the hydrodynamic conditions. These are dependent on the metal itself (its viscosity), and also on the runner system (rate of flow, resistances). During this time in the volume of the casting and mould, a pseudo-initial temperature fields is generated which is significant for the filling of the mould cavity and also for further cooling and solidification of the casting.

Abstract: By the help of simulation software it is possible to follow and predict the high pressure die casting process. In the Department of Foundry Engineering at the University of Miskolc, Hungary we use both Finite Element- and Finite Difference programs for simulation. In this paper we examine a special specimen, a plate with knobs, witch has point symmetric hot spots and cored parts which effect the characteristic of flow and solidification. We examined the solidification process and the temperature distribution. We determined that the finite element method, because of the meshing and the calculation mode, is more suitable for the simulation of thermal processes.