抄録
A process of CNC incremental forming in which a cylindrical shell is formed a flat blank by means of conical incremental stretching and subsequent reverse incremental drawing, has the advantage of adaptability to small-lot production of cylindrical shell parts. Although the forming limit has been reported for the conical incremental stretching, the limit has not been illuminated previously for the cylindrical incremental drawing. Here we report the forming limit in the cylindrical incremental drawing of aluminum sheets. It is found that the forming limit is governed by occurrence of versatile rupture modes, and these rupture modes are avoidable by controlling the tool-path schedule in the process. Furthermore, experimental results show that the tool-path pitch is a dominant parameter in determining the success or failure of the process, because the excessive tool-path pitch forms the excess metal into a plastic hinge line in the vicinity ahead of the tool, and thus adds resistance to incremental drawing flow, which promotes rupture.
