COMPUTER DESIGN OF IMITATION COMPRESSOR BLADE ISOTHERMAL FORGING
Because of the complex geometry of compressor blades a comprehensive approach should be taken to designing of corresponding forging processes. This comprehensive approach encompasses the following: geometric modelling of a forging; computer simulation of the plastic forming process taking place in the die and of the stress-strain state of the tool; 3D design of dies and the use of CNC machines for die tooling manufacture. The application of the comprehensive approach for the development of a forging technology for isothermal forging of compressor blades can help reduce the lead times, enhance the quality of forgings and the durability of dies. Design of 3D parametric associative models using various CAD systems can ensure a higher quality of the design documentation for die tooling. With the help of computer simulation of metal flowing in the die one can estimate the probability of such defects as pinches and folds, the level in the die cavity, the optimum position of the workpiece relative to the fixed reference. The latter is important to ensure acceptable metal consumption rates when designing the forging and the die loads. For computer simulation of the metal flow in forming operations, hardening curves were used of the heat-resistant aluminium alloy Al-5.3 Cu-0.8 Mg-0.5-0.3 Mn Ag-0.15 Zr, which were obtained after the standard samples had been upset at 420°C and at different strain rates, which were consistent with the strain rate intervals and the degree of strain as determined through simulation. The use of CNC machines for die tooling manufacture ensures high accuracy of the tool geometry. The authors examine the plastic forming process of such operations as closed-die upsetting, direct extrusion, and closed-die forging. With the help of modelling the optimum shape and dimensions of the workpiece were identified after all the forming operations. The article includes the results of a successful pilot forging operation when an imitation blade was produced using the process which had been developed by implementing the comprehensive approach to design in a production environment.