A research on a new structure of forming tool in Single Point Incremental Forming (SPIF)

Abstract

Single Point Incremental Forming (SPIF) is really a new technology of forming metal sheet nowadays and in recent decades. Although it was invented in, 1967 by Lezak, an American inventor, but the applications of the innovative technology were broad from 1990 because of the advance of controlling technology. This technology is especially adapted to small batch, unique or single productions. There are many forming parameters that influence to the formability of the metal sheet workpiece such as diameter of tool, the revolution per minute of the tool tip, the vertical feed rate after each orbit, the velocity of tool in horizontal plane…. Among of them, in our own experiences, we recognize that in almost all cases, the revolution per minute of the forming tool when forming ferric material sheet such as mild steel, stainless steel, hard steels… should be as small as possible to get the biggest ability of deformation of the workpiece sheet to get rid of failure on the lateral edge of the sheet. The tangential velocity of forming point on the spherical tool tip should be selected to attain the situation of rolling but no sliding of the surface of the spherical tool on the one of the sheet material. The paper recommends a new version of a forming tool in which the tip of the tool is a very hard ball (such as the quenched ball in a ball bearing) that is freely rotate by the friction to modify the contact point on the spherical surface of the tool to avoid the abrading and keep the spherical shape and the situation of rotating but no sliding on the surface of the workpiece sheet as mentioned above. The manufacture of the innovative forming tool is performed and then empirical processes verified it. The models formed by the typical tool are better in comparison with the ones of normal forming tool.