The Inhomogeneous Deformation Behavior Research On The Multi-pass Roll Forming Of Super Alloy Ring With Complex Cross Section

The thin-walled high temperature alloy ring with complex cross section is key part for mechanical seal, and the multi-pass roll forming technology is one of the most effective forming methods to manufacture this type of ring. However, the local plastic deformation of thin-walled ring is not uniform during multi-pass roll forming for the ring’s features of complex cross section, large diameter and small cross-sectional dimension, etc. A variety of defects were produced by the inhomogeneous deformation controlled improperly, such as crack, not round, wrinkle, etc. and the quality and use characteristics were affected by it seriously. Therefore, the multi-pass roll forming process for high temperature alloy ring with complex cross section was studied by using numerical simulation combined with the method of experiment and theory analysis. And the influence laws of forming parameters on the inhomogeneous plastic deformation in multi-pass roll forming process were analyzed systematically. Research results in this paper are as follows:The material constitutive model was established based on the basic mechanical property of the thin-walled ring(GH4169). An FE model of multi-pass roll forming for the high temperature alloy thin-walled ring has been established under the elastic-plastic finite element analysis software ABAQUS/Explicit based on the solution of the key techniques, such as geometry modeling, contact boundary, meshing, etc. The accord with actual conditions and both computational efficiency and accuracy were taken into account, and the reliability of the model has been validated by experiments.Based on the model, the variation laws and distribution characteristics of equivalent stress and equivalent strain of the thin-walled ring were studied systematically during the multi-pass roll forming process. The results show that: the maximum equivalent stress increases rapidly during the driven roller feed stage, then nearly keeps unchanged during the roll forming stages; the equivalent stress along the width direction is inhomogeneous, and the maximum equivalent stress is located at the bending region; the equivalent plastic strain in the first pass roll forming process increases continuously, and the equivalent plastic strain shows stepwise upward trend in the second and fourth stage.The influence laws of uneven plastic deformation of the thin-walled ring in multi-pass roll forming process have been obtained. The results show that: with the friction between the driven roller and ring increasing, the uneven deformation degree decreases first and then increases; with the friction between the driving roller and ring friction increasing, uneven plastic deformation degree exhibits a tendency to increase, and when the friction coefficient is less than 0.2, the uneven plastic deformation is little affected by friction; the inhomogeneous plastic deformation of ring is little impacted by the friction between guide roller and ring. The higher the feed rate, the greater the inhomogeneous plastic deformation. The inhomogeneous plastic deformation is not affected by the rotation rate of driving roller.