Effects of roll sizes on uniformity of strain and variation of configuration in cold-closed T-shaped rolling process of HE30 aluminum alloy ring

During ring rolling process, the roll sizes have significant influences on the forming quality of the deformed ring as well as the stability of the rolling process; thus, some works have been done on roll size effects in recent years. However, the previous work just focused on plain ring rolling process and the obtained results cannot be simply transplanted into profiled ring rolling process. In the profiled ring rolling process, due to the simultaneity of the expanding deformation of the ring radius and the configuration forming of the ring cross section, the effects of roll sizes are more complicated than that in the plain one. To reveal the discrepancies between the two rolling processes, the effects of roll sizes (i.e., the radius R (D) of the driving roll, the radius R (M) of the mandrel, and the fillet radius R (f) of the groove entrance) on uniformity of strain and variation of configuration in cold-closed T-shaped ring rolling (CCT-RR) process are investigated deeply in this paper. The results show that (1) the ring is more likely to generate inner flaws and surface cracks if rolled by larger R (D) or smaller R (M) or larger R (f); (2) with R (D) or R (M) decreasing or R (f) increasing, the expansion of outer radius decreases, so do the expansion of outer radius, while the filling depth increases; and (3) the equivalent plastic strain in the outside layer of the ring decreases with R (D) increasing or R (M) decreasing, but that in the inside layer increases faster; with R (f) increasing, the outside layer increases and the inside layer decreases almost at the same speed in terms of equivalent plastic strain. The results will not only reveal the deformation mechanisms of CCT-RR process but also provide an important guideline in the processing design of the relevant cold profiled ring rolling processes.