Research On The Parts With Small Forming Angle In NC Incremental Forming

As a novel kind of plastic processing technology, NC incremental forming uses the principle ofrapid prototyping. In the process of forming, the part will be formed step by step under theNumeric-Controlled tool on the NC equipment. Incremental forming with its advantage of low cost,short cycle and Flexible manufacturing has a wide range of application in the field of auto industry,medical industry and aerospace industry. This paper focuses on the research of the parts with smallforming angle. The mechanism of defects and factors that affect the precision are analyzed, andseveral precision improvement plans are proposed which are proved to be effective in experiments.Main results are summarized as follows:1Research on the mechanism analysis of incremental forming. The change rules of the thicknessand strain of the sheet metal are studied. During the forming, the sheet metal is divided into three area:formed area, contact area and unformed area. The state of stress and strain in each area is analyzed,and two significant factors affecting the accuracy, springback and residual stress, is also studied.2Study on the forming defects and factors. The reasons of center bugle and edge wrap on thepart with small forming angle is analyzed. By researching the small curvature spherical part throughexperiments, the influence of the yield strength, thickness, forming step and tool diameter to theforming accuracy is found. So these factors can be optimized.3Propose several ways to eliminate the bulge. The methods of compensation, Multi Stage andpositive forming have been used in this paper. Test results shows these methods are very effective toeliminate the center bulge and improve accuracy. And each method has its advantage, differentmethods can be chosen, according to the accuracy requirement4By forming the practical part to verify the feasibility of the optimization methods. And alsotwo ways are proposed to solve the problem of edge wrap. Annealing is used during the negativeincremental forming, and Edge warp produced in positive incremental forming can be solved bysettling preloading quantity of the elevating. By using the methods, get ideal part can be goteventually.