Development of an Integral Production Process for Manufacturing Machinery Billets Based on Computer Simulation

Abstract

Examples are presented of using computer simulation for evaluating the effect of production parameters on billets' quality properties and development based upon this of rational production regimes. Criteria evaluated during simulation for solidification and forging criteria are described. The possibility is considered of using results obtained during simulation of solidification as starting data in modeling forging processes. One method of reducing the manufacturing cost of metal products, improving the level of mechanical properties of structural and functional materials, and also a way to reduce the scatter of these properties is prior simulation of production process stages and revelation of the optimum values of production parameters. In each stage of a production cycle, billet qual- ity is described by its own collection of criteria, whose values mainly govern features of the further conversion technology. In view of this, development of production processes (including the use of computer modeling) for each subsequent stage should be performed taking account of the maximum amount of billet-semiproduct quality characteristics achieved in the course of preceding stages. Questions of developing integral production processes based on computer modeling have been the subject of many publications, the last of which is work in (1-2). Modeling solidification. The first stage of the cycle for producing billets for engineering, whose technology may be developed on the basis of results of computer modeling, is ingot pouring and solidification. In order to model processes occur- ring in this stage, there is a considerable number of special program products, i.e., Procast, Magma, LVM-Flow, Thercast, and the domestic product Polion. At the Central Research Institute of Machine Building Technology (TsNIITMASh), a computer program of in-house development, called "Large Ingot" (4), and the ProCast commercial program are used for this purpose. The fundamental approach to developing technology for obtaining an ingot involves planning an orthogonal two- factor experiment with a study of the effect on ingot quality test characteristic, mainly parameters governing ingot solidifi- cation features to a considerable extent, i.e., conicity and ratio of ingot height to its central diameter (H/D). As variation parameters it is also possible to use the proportion of sinkhead and/or kumpel part of an ingot, thermophysical properties of the heat insulation materials used, mold wall thickness, etc. The dependence of a test ingot quality characteristic on these parameters is evaluated as a rule by a second order regression equation. The test characteristics considered are pore volume in the axial porosity zone, dimensions of this zone, concentra- tion of liquates over an ingot cross section (primarily, carbon, sulfur, and phosphorus), and distance between dendrite axes.