Experimental feasibility study of forming copper sheets by vacuum forming method

Vacuum forming is one of the forming processes of plastic sheets. This process is particularly popular due to its simplicity and high production speed and the removal of one of the dies. The main idea of this research is the feasibility of generalizing the vacuum forming process for forming metal sheets. For this purpose, the available design alternatives were considered. In the experimental tests, the shape of the die and, as a result, the workpiece, was considered as a sector of sphere. By comparing the stress-strain diagram of Polyethylene terephthalate, which is widely used in vacuum forming, with the diagram of pure copper sheet, the temperature of 600 ºC was chosen for this purpose. A high-frequency induction furnace is used for heating the workpiece. Also, by using two pneumatic jacks, auxiliary forces have been applied to form the sheet. On the surface of the blank holders, using a drawing bead in the form of a ridge with a circular cross-section, has been tried to eliminate the wrinkling caused by forming. Among the different thicknesses of the studied sheet, it is possible to form copper sheets in the range of 0.4 to 0.7mm up to a total drawing ratio of 58% still, but with the current configuration, sheets with less thickness should be studied.