Effects of spinning parameters on microstructures of ellipsoidal heads during marginal-restraint mandrel-free spinning
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Effects of spinning parameters on microstructures of ellipsoidal heads during marginal-restraint mandrel-free spinning Jia-Yang Chen1 • Yong-Cheng Lin1,2
•
Guo-Dong Pang1 • Xin-He Li1
Received: 11 March 2020 / Revised: 30 June 2020 / Accepted: 1 August 2020 Ó Shanghai University and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Marginal-restraint mandrel-free spinning is an advanced technology for manufacturing ellipsoidal heads with large diameter-thickness ratios. The effects of spinning parameters on the forming accuracy of ellipsoidal heads have been studied, and optimized spinning parameters have been obtained. The microstructure evolution of a workpiece is usually very complicated in the spinning process. In this work, the influence of spinning parameters on the microstructures of two-pass spun ellipsoidal heads is studied. It is found that the forming angle and feed rate of the first pass, angle between passes, and feed rate of the second pass significantly affect the microstructures. Meanwhile, the evolution rule of the microstructures near the inner and outer surfaces of the spun parts is almost consistent. A large forming angle, large angle between passes, or large feed rate of the second pass are beneficial to obtain uniform microstructures. A small or large feed rate of the first pass reduces the microstructure uniformity. To improve the microstructure uniformity between the inner and outer surfaces, the optimized spinning parameters are determined. Keywords Spinning Thin-walled ellipsoidal heads Spinning parameters Microstructure evolution
& Yong-Cheng Lin [email protected] 1
School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, People’s Republic of China
2
State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, People’s Republic of China
1 Introduction The spinning forming technology is one of the near net forming processes, and it is extensively used to manufacture axisymmetric workpieces [1, 2]. The diameters of spun workpieces can range from 3 mm to relatively large ones, such as 10 m [3, 4]. Marginal-restraint mandrel-free spinning is an important spinning process [5], which has the advantage of no wrinkle defects compared with the traditional mandrel-free spinning [6, 7]. Usually, it is possible to control the forming accuracy of spun parts by adjusting the spinning parameters [5, 8]. However, high-quality spun parts should have not only good dimensional accuracy [9–12] but also an ideal microstructure uniformity [13–15]. In the spinning process, non-uniform deformation of the workpiece easily occurs, which affects the final microstructures and service performance [16]. Therefore, to obtain uniform microstructures, it is necessary to study the effects of spinning parameters on the microstructures of spun workpieces. In mandrel-free spinning, only one side of the workpiece is in contact with the roller, and the other side is in a noncontact state [5]. Therefore, compared with the case in mandrel spin
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