Technology Research For Spinning Forming Of Long Spiral Bellows Based On Numerical Simulation

As flexible connection parts,bellows are broadly used in aerospace,petrochemical industry,instruments,ships,refrigeration and other fields.In its numerous forming process,spinning forming plays a significant role in the shaping of bellows for its high production efficiency,low cost,high forming precision,etc,especially in the shaping of small diameter and length of unlimited bellows,which has the advantages that other process can't match.In this paper,for the spinning forming of long spiral bellows,the numerical simulation and experimental study were combined to discuss the deformation characteristics of bellows,as well as the quality problem that will appear in the forming process and its impact factors,which lay a foundation for the design of process.Based on the study of spinning forming process and the basic theory of finite element,the deformation partition in the spinning of bellows was established,the pressure and deformation in the different location of deformation zone were analyzed.Then,spinning process was compared to the deep drawing and necking process,and the preliminary forming program was determined.On the basis of them,with the help of finite element software to simulate the spinning process of spiral bellows,and understand the multiple deformation characteristics of bellows,as well as the quality problem that will appear in the forming process and its impact factors.In order to complete preliminary forming program,this paper also through the single factor method to analyze the influence of tube size,material properties and the rotation speed of spindle on the width of deformation zone,as well as the impact of the ratio of the pitch and the width of deformation zone on the peak diameter.Then,the better forming process parameters were determined,and the simulation results were verified by the real experimental study.The results of the numerical simulation show that:The maximum deformation was in trough of spiral bellows,and it had circular and axial compression deformation,radial elongation deformation.It's difficult to control the peak diameter.When the ratio of the pitch of wave and the width of deformation zone P/W was greater or equal to 1.12,the peak diameter of bellows was equal to the tube diameter.Thus,when the ratio was less than 1.12,it's necessary to increase the tube diameter and adjust the process parameters to ensure the peak diameter.Based on using single factor method to analyze the influence of various factors on the peak diameter of bellows,the preliminary forming program was improved.When the tube diameter d was 38mm,the strain hardening exponent n was 0.26 and the rotational speed of spindle ? was 300r/min,parts with high dimensional accuracy could be obtained.The experiment results show that the experiment results of preliminary forming program and the improved program were consistent with the numerical simulation.And the bellows formed by improved program could meet the dimensional requirements of the part.