Optimization Of Drawing Process Based On EPM Technology Zonal Blank Holder Method

Sheet metal deep drawing is often used to produce thin-walled parts with certain strength and stiffness.The key to the process of deep drawing is to select the proper blank holder method and apply proper blank holder force load.According to the application requirements of blank holder force and the characteristics of electric control permanent magnet(EPM)technology,the EPM zonal blank holder method is adopted to optimize the process parameters from the angle of improving the deformation uniformity,it is of positive significance to explore the metal flow law in sheet metal forming process controlled by EPM technology.Based on the deep drawing of box-shaped and cylinder-shaped parts,the EPM zonal blank holder method is adopted,the main research contents are as follows: the principle of EPM technology,the influence of magnetic field and magnetic attraction are studied;Aiming at the deep drawing of box-shaped part and cylinder-shaped part,the region current is optimized,the forming process is simulated,and the blank holder methods are compared and analyzed,the simulation results and the validity of the zonal blank holder method are verified.Firstly,the divisible magnetic pad with 46 magnetic pole units was designed,and the magnetic force of divisible magnetic pad with 46 magnetic pole units was estimated to be185748 N.The law of mutual influence among subareas and the factors affecting magnetic attraction of magnetic pad were studied.Secondly,the EPM die was designed,and the magnetic-mechanical coupling simulation was carried out by using COMSOL software for the full-area,single-area,double-area and three-area loading modes of the magnetic pad.The results show that it is more suitable to apply blank holder force to divide the magnetic pad into fillet area and straight area.For axisymmetric parts formed by non-axisymmetric blank holder device,uniform blank holder effect can be achieved by optimizing the blank holder force in the region.The deformation of the suction plate after magnetic-mechanical coupling was analyzed,the maximum is 0.09 mm.Thirdly,according to the non-uniformity of metal flow in the forming process of box-shaped parts,the regional current was optimized,and from the point of view of metal deformation uniformity,the various blank holding methods were compared and analyzed,the maximum thinning rate of the box is increased by 15.55%.According to the deformation characteristics of the cylindrical part,the current in 1,2 and 3 regions was optimized,and the optimized blank holder force loading scheme is more suitable for the deep drawing of the cylindrical part.Furthermore,the advantages of the zonal blanking process with EPM were verified.Finally,08 AL cold-rolled steel sheet was selected to carry out the drawing experiments of box-shaped parts and cylinder-shaped parts respectively.The experimental results show that the optimized zonal blanking process can make the metal flow more uniform and improve the sheet forming performance.