Experiment And Numerical Simulation On Stagger Neck-spinning With Double Rollers

Conventional neck-spinning process with one roller needs many passes to machine a tube, which means lower efficiency. To improve the efficiency, stagger neck-spinning with double rollers is presented in this paper. The tube clamped by spindle head has high-speed rotation. The rollers which are divided into the front one and the rear one have an axial dislocation. The front one has a smaller radial feed than the rear one, and both of them have the same axial feed. Therefore, the stagger neck-spinning with double rollers is twice the efficiency of conventional neck-spinning. It was discussed from the following aspects in this paper,(1) Via an infinitesimal method, the theoretical formula on force calculations of conventional neck-spinning were derived by force equilibrium equations and geometric relations. However, compared to conventional neck-spinning, the contact state between rollers and tubes in stagger neck-spinning is different. Based on the force calculations of the front roller,both of the front and rear rollers in stagger spinning was deduced by modifying the relevant parameters.(2) An octagonal ring transducer is designed for measuring the spinning forces in three directions. The validity of the octagonal ring was verified by the theoretical calculations, and the positions of strain gauges were designed by strain analysis. The spinning force in different process parameters was measured by octagonal ring transducers and a dynamic stress-strain instrument. The theoretical calculation substantially coincide with the experimental value after filtering the test data.(3) The numerical simulation about stagger neck-spinning was conducted based on the Dynamic Explicit model in Abaqus. The results under different process parameters were compared with counter roller spinning. An analysis of stress and strain distribution was made in this paper. The results show that the tube under counter roller spinning has a uniform wall while the tube under stagger spinning has few wrinkles. It was found that the radial feed of both the rollers, the axial distance between rollers and the axial feed rate do affect the quality of the tube.(4) Optimization on the process parameters of spinning with orthogonal test was presented for a reference. The radius of tube bulging, the ratio between the maximum radial force and the axial feed, and the ratio between the maximum radial force and the minimum radial force were taken as indicators, and three process parameters’ impact on the three indicators have been discussed. Combining the best experimental schemes of single indicator, the best experimental scheme was obtained under the present level of orthogonal test.