Research On Process And Parametric Design For Billet Of Ring With Conical And Flange Cross Section In Radial-Axial Ring Rolling Based On Electric Field Method

Radial-axial ring rolling is an advanced process to produce seamless rings. This process is applied through the radial and axial motions of work rolls, making the ring cross section formed and the ring diameter expanded. Radial-axial ring rolling is mainly used to produce large diameter rings. Compared to the traditional process, it has advantages in higher production efficiency, lower cost, better precision, and material and energy saving. So it is widely used in aerospace, machinery, metallurgy, railway, chemistry and energy industry.Though it has been about 200 years since ring rolling process was invented, many domestic plants still design the process by trial and error due to its complexity, causing plenty of waste in time, human and material resources. It mainly includes: 1) for a given ring product, there is no instruction for billet design, and billet is determined by several times of try, which is time-consuming and low efficiency; 2) feeding design of rolling process is not reasonable, poor stability during the process and causes high waste rate. Especially for profiled ring rolling, defects such as cross section underfilling, ring diameter over expansion, distortion and folding always exist.To solve the billet design and feeding design issues in radial-axial ring rolling, studies in this paper are made as follows with a typical conical flange ring as the research object:① The principle of electric field method for preform design is discussed, and the method is used for billet qualitative design for conical flange ring. From the equipotential contour of electronic field, the qualitative contour of billet is obtained.② The qualitative contour of billet is improved and parameterized, and with the central composite design and finite element analysis, a response surface is obtained, in which the filling rate is object and the billet dimensions are parameters. From the response surface, the reasonable ranges of billet dimensions can be determined.③ The cross section filling of conical flange ring and the reasons why underfilling exists are analyzed. As a result, a map showing the underfilling defect corresponding to the billet dimensions is formed. With different billets, the rolling force and strain distribution during rolling process are analyzed, and it is believed that ring billet have no apparent relationship to the rolling force and stain distribution.④ The effects of feeding rate on the cross section filling, rolling force, strain and temperature distribution uniformity are also discussed. The results show that larger feeding rate is beneficial for the improvement of cross section filling, strain and temperature distribution uniformity, but rolling force peak will increase.⑤ The detail rolling process proposal is defined, including the billet dimensions and feeding curve. The practical production for the conical flange ring was carried out, the good macroscopic dimensions and microstructure of final ring product indicated that the process design is reasonable and is feasible.The electric field method and experiment design method is applied in this paper for the qualitative and quantitative design for ring billet. It is helpful to rapidly to obtain the optimized billet with a relative low computing cost and improve the efficiency of process development. This methodology is also suitable for billet design of other profiled ring rolling.