The cold deformation work hardening characteristics of precision stainless steel tubes

In certain specialized industrial fields, it is usually necessary to fully utilize the cold deformation and work hardening characteristics of precision stainless steel tubes to meet specific usage requirements. Cold spinning is a special type of cold deformation processing method. The multiple cold spinning processing of precision stainless steel tubes often requires intermediate stress relief annealing, resulting in a large number of processes and low operational efficiency. To reasonably arrange the cold spinning process and achieve better processing results, it is necessary to conduct finite simulation of the deformation and temperature field during the cold spinning process, providing a basis for the determination of the cold spinning production process of precision stainless steel tubes. 

The researchers established a finite element model for the precision stainless steel tube, taking into account the complete cooling of the mold, applying convective and heat transfer boundary conditions, and calculating the deformation and temperature field distribution of the precision stainless steel tube during the forming process. 

During the pressing process, the material protrusion occurs in the concentrated deformation zone of the rotating wheel, unlike the three-roll planetary rolling process which has a distinct triangular effect. This is because the rotation of the three rollers is at different distances from each other, and each wheel contacts the blank one after another. When each wheel contacts the workpiece, due to the processing feed, the circumferential rotating wheel cannot fully contact the surface of the workpiece. Under the three-dimensional force condition, the lateral deformation and axial deformation are correspondingly restricted, and the metal flows out through the gap of the rotating wheel. The material flow is not restricted, and the cross-sectional shape always remains circular. 

Effective deformation effect analysis is helpful for studying the deformation mechanism of the three-wheel misaligned spinning press and the quality of the spun pipe. The instantaneous contact area is large, and the frictional heat and plastic deformation heat can be accumulated rapidly from the three spinning wheels, starting from the spinning and rolling processes. The steel billet temperature rises rapidly within a few seconds, and the heat exchange with the outside world is much faster in terms of heat dissipation. The distance between the three spinning wheels for spinning is a process of accumulating instantaneous plastic work and generating high temperature. Through simulation analysis, the reasons and mechanisms for the rapid temperature rise of the precision stainless steel pipe during spinning can be understood.