Then, base forming is applied to make the bottom part flat using the end shape of a punch and a knockout device in order to prevent forming defects in the forming process .
[8] The product shape in this study was the rectangular cup shape shown in Figure 1. Its length, width, and height were 170, 45, and 140 mm, respectively.
The process is divided into five separate processes, except for a trimming process, as shown in Figure 2, which shows the changes in the shape of the product at each step.
The first drawing process involved sinking work, with no blanking or changes in the thickness of the wall occurring in the raw material. Because no clearance was applied, the blanking punch performed the role of a stripper in the drawing work.
The ironing processes were conducted sequentially from the second deep drawing step to the fifth step to create the final shape.
For all the processes except the first, we installed a knockout device to transfer and pull out the finished material from the die without using a stripper.
This knockout function induced side forming of the product, while a compressive force was applied to the bottom side during the drawing.
The A-1100 used for this study contained 99% aluminum and possessed a good nonscaling property as well as excellent heat conductivity.
In addition, although its strength was relatively low, it had the advantage of easy forming processability.