JUNCTION FORMING IN ALUMINUM TUBES USING AN ELASTOMER TECHNIQUE

Abstract

This article describes an experimental machine using an elastomer rod for developing junctions on aluminum tubes, and is put forward as an effective process under a limited range of operational conditions. The operation is achieved by applying loading–unloading cycles to the tube and the elastomer simultaneously. The success of the operation is governed by the mechanism that controls the relationship between the displaced volume of the elastomer and the reduced length of the tube during the forming process. This is based on several experiments that confirm the validity of an empirical relationship between these parameters. The experiments were performed on material having different work hardening behavior, using various forming configurations, including T-forming and cross-junctions of the aluminum tubes. The specially designed tools cause simultaneous biaxial compression of the elastomer rod and the tube, and as a result, only one cycle was needed to form the desired junction. Previously, more than 50 cycles of loading–unloading were needed to perform the same operation. Note that in this type of process, the frictional forces between the elastomer and the inside surface of the tube are an important factor in contributing to the reduction in the tube length during the forming operation. It might appear that optimum conditions would be those giving the greatest amount of axial shortening, thus leading to greater circumferential expansion. Therefore, for greater circumferential expansion, an extra length must be fed into the die space. For this reason, special mechanism tooling was developed to achieve this purpose. Other relevant parameters were also examined and analyzed.

Keywords:

• Buckling in tube forming
• Clearance height technique
• Cross junction
• Elastomer forming
• Forming of aluminum tubes
• Friction in tube forming
• Junction forming
• Rubber forming technique
• T-junction
• Tools for simultaneous compression
• Tube chamfering technique
• Tube forming
• Tube forming machine
• Unconventional forming

Acknowledgments