Deep Drawing of Circular Sheet Metals with Rubber Rings : 1st Report, The Case of First Drawing Operation

Abstract

For the process of so-called " punchless deep drawing", an optimum drawing condition is investigated under which the height of the drawn cup increases efficiently. Considering the dimensions of the rubber ring, the applied compressive load and lubricants for the contact surface between blank and die, the optimum condition for the first drawing operation is determined experimentally. It is especially emphasized that the internal diameter of the rubber ring d₂ should be chosen such that the ratio of d₂ to the die hole diameter d₁ may increase with a decreasing d₁. It is also extremely important to use a thicker ring so far as no fracture occurs at the coupled with polyethylene film. Furthermore, some examples of fractures and depressions at the bottom portion and also flange wrinkles are shown.