Research On Neck-spinning Formability And Forming Process Of High Strength Steel Tube

The spinning formability of metals related to the spinning forming process and exploring the forming properties of materials can fully tap the forming potential of materials,which is the key-precondition for realizing the forming process and selecting the process parameters.For variable diameter tube-shaped parts,the neck-spinning is an effective forming method.Due to the high yield strength and tensile strength of high strength steel,the elastic deformation is large,and the plastic forming at room temperature needs great pressure,which lead to defects.Therefore,parameters containing the forming law of high strength steel in neck-spinning,controlling forming defects,improving forming limit and forming quality are key-points to forming high-performance necking parts.This paper,with important theoretical value and practical significance,can enrich and perfect the theory and technology of neck-spinning.Based on ABAQUS software,this paper establishes the finite element model of high strength steel neck-spinning with double rollers.Wall thickness,roundness and cylinder are taken as the quality indexes to evaluate the combination for the high strength steel in test and necking ratio is used to evaluate the formability of high strength steel.The related parameters for the necking ratio were investigated.The principle of reduction in multi-pass spinning is established in way of uniform for per-pass necking ratio.The forming quality of the multipass neck spinning is simulated and verified.This paper put forward the scheme of forming limit of multi-pass neck-spinning.Firstly,determining the limit range by the large reduction.Then take a small reduction in forward and backward spinning method to obtains the real limit necking ratio in multi-pass of neck-spinning with tube end is 0.56,and the real limit necking ratio of necking-in spinning of tube is 0.46.The deformation capacity of necking-in part is larger than the neck-spinning on tube end part.The results show that,with the decreasing of reduction,increasing of feed rate and roller fillet radius,the wall thickness thinning can be controlled.With same materials,by wall thickness increased,the deformation capacity is stronger.The material with high elongation and low hardening exponent has strong necking formability,the neck-spinning deformation capacity were shown as DP600,DP980,and QP980 respectively.The DP600 high strength steel material has the best neck forming ability.The DP980 in r?=10mm,f=1 mm/r can obtained the real limit necking ratio(m=0.829).Forward spinning can control the forming precision of the outer diameter,the backward spinning can control the uniformity of the wall thickness.The advantages of the two forming methods can be made full use in multi pass spinning.Due to the transfer and distribution of the material in the deformation zone in necking-in spinning,the roller path should be feed in forward and backward ways,and the equidistant trajectory of the wall thickness uniformity control is better than the two ends of the first die forming method.