2010 年 51 巻 588 号 p. 23-27
An experiment on incremental forming of a sheet metal has been carried out to study the mechanism of deformation. A bar tool with a spherical head was made to travel along an altitude trace on an aluminum alloy sheet, and stopped at a certain point during the trace. By detailed observations of the termination point, a simplified model of the deformation process was proposed. Moreover, equations were prepared to predict the distribution of strain, on the basis of plane strain conditions. Strain and strain increments have been calculated under several forming conditions using this model. As a result, the distribution of strain increment along the section of tool trace was analyzed, and it was presumed that the location of the peak influences the strain concentration and the limitation of deformation. If a peak of strain increment locates close to unformed area, it would prevent the advancement of thickness decrease, and make it possible to cause a large strain without breakage. It is considered one of the basic mechanisms of how a huge deformation can be produced by an incremental forming process.