Optimisation of aluminium sheet forming using a flexible die

This paper presents an experimental study of the rubber-pad forming process, which is used widely to produce aerospace and automotive parts, and in other industries which produce sheet metal components. The forming of thin sheet shallow shapes is the most frequent application. The process has a number of advantages over conventional processes: only one rigid tool half is required to form a part; parts with excellent surface finish can be formed as no surface tool marks are created; thinning of the workpiece is reduced considerably; and different metals, of various thicknesses, can be formed using the same tooling. Significant quality improvements for a range of alloys have been demonstrated. The present paper describes the process and the results of work carried out to investigate the capability of the process and to optimise the process parameters to ensure a defect-free product. The experimental investigation was done using a 100 t double-acting hydraulic press to produce a part based on the design of a support rib for an aircraft wing or tail flap. A PC was interfaced with the machine for monitoring, data logging and analytical purposes.