Research Onmulti-point Stacked Flexible Die Forming Process Of Spherical Part Based On Flexible Blank-stretcher

The flexible forming process of sheet metal has been a popular research direction in recent years due to its application to diversification and small batch.In the multipoint stacked flexible die forming process(MSFDFP),forming defects are easily caused when there is no clamping around the sheet,and the main forming defects are wrinkle and large springback.These two forming defects seriously affect the shape of the workpiece and dimensional accuracy.In response to this problem,MSFDFP and its device have been improved.The main research contents are as follows:1.Taking spherical parts as the research object,the forming defects in MSFMFP is analyzed,and the influence of curvature radius of spherical parts on the forming quality is studied.By analyzing the stress state of spherical parts in forming process,the fundamental causes of wrinkling defect is found.2.Adding a flexible blank-stretcher for the multi-point stacked flexible die forming device,introducing the structural composition of the flexible blank-stretcher and the principle of flexible coordination during the forming process.MSFDFP based on flexible blank-stretcher is analyzed,and its basic characteristics and advantages are introduced.3.The finite element model of MSFDFP and its unloading springback model are established.The forming quality of spherical parts are compared when using load mode of no clamping,rigid clamping and flexible stretching.The stress and strain distribution,wrinkling and springback of the workpiece under three clamping modes are compared and analyzed,and the reason for the difference in forming quality are analyzed to demonstrate the feasibility of improved device and process.4.The numerical simulation study on MSFDFP based on flexible blank-stretcher is carried out separately.The specific work is as follows: Influence of tilt angle of stacked flexible die on the workpiece sticking condition is studied;The effect of interaction of the flexible stretching force and the hydraulic machine pressure on the forming quality;the influence of the connection mode of clamp and stretching cylinder on the forming quality;the effect of friction coefficient between contact pairs on the forming quality.