Characterization of loads in die casting and prediction of die deflections
Abstract (Summary)Die casting dies deflect during a casting operation. These deflections affect the quality of the casting operation and the part. The goal of this work is to model and predict die casting die deflections. The theoretical problem is that of determining the thermoelastic deflections of a body under periodic thermo mechanical boundary conditions. This problem is complicated by the existence of several different time and dimension scales. From the perspective of the loads, there are two different time scales: Cavity pressures due to the processes of filling and intensification are applied in fractions of a second Clamping forces are applied throughout the duration of the casting cycle The thermal response of the die is characterized also by at least two time scales: Time for solidification (seconds) Time to reach quasi-steady state conditions (hours). For results to be of practical use, deflections must be computed with a resolution of fractions of a millimeter in models whose size is in the order of a meter. Because of the wide range of conditions, a very important task in this work is that of sorting out the interaction between the different loads, and clarifying what loads are relevant. A modeling approach was developed using ABAQUS, a commercial FEM system. The die behavior predicted by this approach is consistent with what is observed in the field. The procedure is also tested on a limited basis against field data. As a result, values of certain parameters and boundary conditions are defined. Based on the results of the simulations, the behavior of the die has been characterized and deflection data has been prepared in a form that can be used for design purposes. A global perspective of the characteristics of loads in die casting has been prepared. This characterization has allowed a correlation of the behavior of the die with certain die design parameters and process conditions.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/1996