Research On Incremental Forming Of ST16 Tailor-welded Blanks

The NC incremental forming process is a newly developed and dieless technology, which is trying to give a fast and economic solution to form the sheet blank. And tailor welded blanks (TWB) has been given even more and more attention for its advantage by industry and academia. In this paper, incremental forming is first applied to the forming of TWB. First of all, the forming the basis of tailor welded blanks are introduced. Secondly, the plastic formability of the TWB in tensile tests is analyzed with the experiments of the unequal thickness TWB specimens. Thirdly, the formability and wear characteristic of the ST16 steel, which is the base materials of TWB, in incremental forming process under different lubricating conditions are studied. Fourthly,the formability of the TWB in incremental forming process under different process parameters, such as tool size,step size and welding seams positions are studied. The influence of these process parameters are checked by orthogonal test method. The experimental results are showed that:1. In longitudinal test the fracture always occurred on the middle of tensile specimens; in transverse tests, the fracture always occurred on the thinner side.2. The changes of lubrication in incremental forming process could influence the maximum forming angle and the wear character. Maximum forming angle is largest under the lubrication of phosphate treatment and lithium-based molybdenum disulfide grease. And the wear characteristic is mainly an abrasive wear, when the tool force down the certain height. The wear characteristic is mainly an adhesive wear, when the tool forming the section profile.3. The dominant influence in incremental forming process of TWB with different thickness is step size, whereas the dominant influence in incremental forming process of the base materials of TWB is thickness. Tool size and step size have relations with length and breadth of the cracking. Beside in respect of the thickness after forming, TWB differs from the base materials of TWB.This article provides a new forming approach, by incremental forming, for TWB, and this will break the unity of its traditional forming methods.