The Study On The Influence Of Heat Treatment On Residual Stress Of Secondary Strength Spinning Cylinder

The second strong spinning process belongs to the precision pressure processing,the product precision is high,the surface finish is good,the shape of the material grain fine,the strength has a great degree of improvement.In the spinning process,the uneven plastic deformation and microstructure change of the workpiece will lead to the generation of residual stress.Since the existence of residual stress will not only affect the dimensional accuracy of the workpiece,but also increase the probability of fatigue crack of the workpiece,it is necessary to avoid excessive residual stress when machining the product.At present,the commonly used method to eliminate the residual stress of the workpiece is the heat treatment of the workpiece,so it is necessary to study the heat treatment of the cylinder after two times of strong spinning.In this article,the tin bronze(QSn7-0.2)cylinder after two times of strong spinning is taken as the research object to explore the influence of heat treatment temperature and holding time on its residual stress.The main contents include:1.The simulation model of two-pass spinning was established by using 3d drawing software,and the assembly was carried out according to the reasonable process parameters.The simulation of the two-pass spinning process was carried out in the simufact.forming finite element analysis software.2.Continue the process simulation of heat treatment for the cylindrical parts after spinning,design the single-factor experiment scheme,measure the residual stress of the cylindrical parts with different heat treatment temperatures and holding time,and compare the changes of residual stress before and after heat treatment.3.According to the same size as in the spinning simulation and the secondary spinning process parameters,the tin-bronze cylinder was processed,and then the cylinder was heat treated according to the single-factor experimental scheme using a high-temperature furnace.Finally,the residual stress of the cylinder after heat treatment was measured using an X-ray diffractor.Studies show that heat treatment can effectively reduce the second,and the residual stress of spinning piece,but it will not make the change of residual stress in positive and negative value,cylindrical pieces from the surface to the inner surface,the axial residual stress of outside is negative,namely exterior surface is compressive stress,the internal tensile stress,tangential residual stress decreases,and the inner surface is compressive stress,the surface of tensile stress,the equivalent residual stress is tensile stress and gradually decreases,and the distribution is uniform;With the increase of heat treatment temperature and holding time,the absolute value of residual stress in each direction decreases gradually.By comparing the results of the test and the simulation,it is found that the residual stress measured by the two is slightly deviated,but the overall variation trend is the same.The test results are larger than the simulation results numerically,but the error is within 10%.The maximum error of the axial residual stress is 7.66%,and the maximum error of the tangential residual stress is6.67%.Considering a series of factors such as the working efficiency of heat treatment and the release of residual stress,it is an ideal heat treatment scheme to choose 250 ℃ heat treatment temperature and 2h heat preservation time.