Research on the power spinning method of large high-strength cylindrical parts

Abstract

Counter-roller spinning is an effective method to form large metal cylindrical parts due to its small forming force, low mold cost, and flexible processing. A finite element (FE) simulation model of counter-roller spinning was established by Simufact Forming software to process a tubular blank with an internal diameter of 1970 mm and wall thickness of 26 mm. The simulation results show that the radial spinning force of the inner and outer rollers is minimum, and the difference of the radial spinning force between the outer roller and inner roller is smallest when the process parameters are as follows: thinning ratio of the tubular blank Ψt = 20%, forming angle of the roller αρ = 25°, feed rate of the roller f = 1 mm/r, and pairs of rollers m = 4. Comparatively, the average radial spinning force of mandrel spinning is about 1.70 times that of counter-roller spinning. In the stable spinning stage, the equivalent strain difference decreased gradually with the increase of the thinning ratio and increased steadily with the increase of the forming angle of roller. As the feed rate of the rollers increased, the ovality of the workpiece tended to decrease gradually, the deviation value of outside diameter also decreased progressively, and the straightness accuracy increased. The results of the counter-roller spinning experiment show that a mouth-expanding defect exists in the workpiece, which is consistent with the simulation results. In addition, the internal surface quality of the workpiece was better than the external surface quality under the same feed rate. If the feed rate is not reduced, the surface quality will continue to deteriorate as the pass number of spinning increases. After the cumulative thinning ratio of 30CrMnSiA alloy, structural steel reached 69%; the workpiece surface exhibited a peeling defect and required annealing before spinning could be continued. In addition, the deviations between experimental and FE results of the average radial spinning force and the ovality and straightness were less than 12% and less than 15%, respectively.