Computer-aided techniques for improving productivity and quality of the glass-lubricated hot extrusion process.

摘要

The glass lubricated hot extrusion process is a manufacturing process in which the heated billet material is forced through the aperture in a glass lubricated die to produce long complex shapes from materials like steel and titanium. Process parameters like the heating temperature, extrusion speed, type of glass lubricant and die design have to be controlled closely to allow satisfactory extrusion and minimize defects such as surface defects, twisting and shape distortions. A careful analysis of the process is needed to minimize or eliminate these defects.;Initial approaches used to analyze this process led to difficulties because the process is characterized by high temperature gradients (billets at 1200 C, tooling at 300 C), high reductions of area (;A model has been developed which can track the temperature of the billet, predict pressures, lubricant behavior and metal flow during the process. It uses a finite difference method for the heat transfer analysis, an iterative scheme for predicting pressures and exit temperatures, an analytical method for the lubrication analysis and an upper bound model for predicting metal flow. A comprehensive "state of the art" literature review and patent review have been conducted. All aspects of the extrusion process, including heating, billet transfer, extrusion metal flow and lubrication have been modeled. The predictions of the model show good agreement with experimental observations and finite element simulations (errors are less than 10%). However the time for the analysis (