Study On Incremental Sheet Forming For Stainless Steel Asymmetrical Double-layer Body

Characterized by small forming force,high flexible process,low process cost and high quality,computer numerical control(CNC)incremental sheet forming(ISF)is a new die-less forming technology,which employs simple-shape forming tools to conduct partial plastic forming,and obtains the final part by accumulating plastic deformation.Suitable for small batch production,large varieties trials and rapid prototyping,ISF can meet the needs personalized production,thus it has a broad development prospects and potential market application.At present,partial die is usually applied during the ISF forming process in the industry.However,in order to better improve the processing efficiency and reduce the processing cost,die-less forming will lead the market in the long run.With regards to the die-less double-sided incremental forming(DSIF),the current research mainly concentrated in pure scientific research field,and the shapes selected are generally symmetrical with single layer.However,the expectation from the industry for ISF is to achieve rapid prototyping for the most complex shape with shortest time and lowest cost.In this paper,an innovative asymmetric double-layer structure was designed,and the feasibility of forming in one-step DSIF was checked.The main work and the innovation are listed as below:Firstly,the complicated structure with double-sided incremental forming was simulated by finite element method,and the conclusion is drawn that the single use of double-sided incremental forming will lead to the unevenness of the double-platform sheet metal.Secondly,two kinds of multi-step forming processes were designed.After the experiments,it could be found found that the multi-step forming method can effectively improve the flatness and overall depth of the part.Finally,by comparing the experiments of simple pyramid forming under the method of Single Point Incremental Forming(SPIF),DSIF and DSIF-Peripheral(DSIF-P),a conclusion would be made that the Double-Sided Incremental Forming-Peripheral provides the best flatness around the flange area and the best overall depth.Inspired by the fact that DSIF-Perimeter method provided better geometry accuracy than DSIF,a mixed trajectory method was designed to form such complicated structure.The idea of this forming method is:Based on the DSIF trajectory,reading and optimizing the trajectory by using interpolation and then determine the starting point of each loop,matching the path of of the two tools by keeping the percentage of the arc length equal.The results showed that the modified mixed forming process can improve the forming accuracy of depth while ensuring the flatness of the plate.So it can be said that the performance is better than that of the traditional incremental forming process and the problem of discontinuity caused by the interference of the moving tool and existing part.