Application of Process Modeling to Shell Drawing Operations

摘要

The manufacturing of artillery shells involves a number of metalforming, machining, and heat treatment operations. Cold or hot drawing shells, where the wall thickness of the shell is reduced while keeping the inner diameter essentially unchanged, represents an important step in the forming operations. From the point of view of deformation mechanics, the analysis of metal flow and stress in shell drawing is very complex. The effect of friction at the tool-material interface, the heat generation and heat transfer during deformation, and the effect of strain, strain rate and temperature on the flow properties of material are difficult to analyze and predict, since a process model must be realistic and should not neglect the effort of significant process variables. The mathematical models and the computer programs capable of optimizing the shell drawing process for actual artillery shells and cartridge cases were developed earlier. These mathematical models were based on the analysis of plastic deformation and included the effects of the various process variables (such as punch speed, billet temperature, and lubrication), the properties of shell, die, and punch materials, and the die configuration (both conical and streamline). These models were computerized so that they can be used to analyze the mechanics of the process and predict potential material failure (such as punch-through), and optimize the die configuration and process variables. These mathematical models were expanded to simulate shell drawing through multiple dies in tandem with a tapered punch, as shown in figure 1. Graphical display capabilities were also included during computerization of the expanded math models. (Author)