OPTIMIZATION OF SUPERPLASTIC FORMING TECHNOLOGY

The objective of this paper is a superplastic forming (SPF) technologies design and optimization. The conditions of superplasticity are very sensitive to strain rates and temperature characteristic of deformation process. The presented work gives an approach to design the SPF technologies that satisfies such conditions. A possibility to decrease the temperature of the industrial forming of the Ti-6Al-4V alloy is considered. On the basis of experimental data obtained the three-dimensional computer approximation of mechanical characteristics of Ti-6Al-4V alloy was constructed. It was made in a broad range of temperatures and strain rate, taking account of strain hardening and structure parameter affect. Tension tests of workpieces were carried on up to the destruction. Laboratory studies of the material mechanical properties show that the temperature of industrial superplastic forming can be lowered. A developed mathematical model is proposed and enables to calculate an optimum pressurization taking into account the structural state of the shell material and principles of the shell friction on the die surface. The calculated pressurization enables to obtain the optimum superplastic properties of the material in the preset area of the deformed shell. The proposed model has been tested experimentally. In laboratory conditions, forming of special workpieces with calculated pressurization has been conducted. The experimental researchers confirm theoretical forecasts concerning an ability to decrease the forming temperature of Ti-6Al4VSPF. According to the designed method the theoretical forecasts of industrial shells formchanging in flight vehicles were computerised. The calculation for optimization of manufacturing parts of a jet plane flanks apply a method of superplastic gaseous forming compatible with a diffusion boundary is implemented.