Numerical Simulation And Technology Optimization Of Hot Bulge Forming Process Of BT20Titanium Alloy Cylindrical Workpiece

Vacuum hot bulge forming is a new processing method. According to material hightemperature softening and stress relaxation principle, it utilizes the difference in the thermalexpansion coefficient between workpiece and die to form the workpiece through thermalexpansion force of the die. Vacuum hot bulge forming process of the workpiece deformationis elastic and plastic deformation which is occurred in the low stress state, and directly relatedto the d heating temperature and holding time. Due to the complexity in hot bulge formingprocess, the parameters selection, mold size design of traditional vacuum hot bulge formingprocess mainly based on experiments and experience, and obtained from large amounts ofexperiment and repeated trial and error which is designed with experience and analog byengineering technical personnel. It has a long cycle, poor process optimization shortcomings.With the development of computer software and hardware and the perfecting of finite elementmethod, finite element analysis becomes a very powerful technique to study vacuum heattreatment and hot bulge forming processes．The simulation is able to collect information ofvarious fields during the vacuum heat treatment and hot bulge forming processes，whichprovides scientific foundation for determining the optimal process parameters and ensuringthe quality of the workpiece．The present research chooses BT20titanium alloy as the research objects, studied thestress relaxation behavior and construct relaxation equation through the stress relaxationexperiment. And the compile the creep procedure by the relaxation equation. Established athermo-mechanical coupling model for the vacuum hot bulge forming process of titaniumalloy cylindrical workpiece. Take the creep procedure into the model and utilizes thenonlinear finite element software MSC. Marc to simulate the vacuum heat treatment and hotbulge forming process, analyzes the temperature field, deformation field and stress field，andoptimized the technology parameters by BP neural network,explores the methods to confirmthe technological parameters for vacuum hot bulge forming of titanium alloy cylindricalworkpiece, which provides the theoretical guidance for actual manufacture.