External-internal composite spinning technology for forming thin-walled Ω-sectioned ring of superalloy

The extremely thin wall (0.25 mm) and the Ω-sectioned profile of the ring together with the difficult-to-deform superalloy bring difficulties to forming technology. To address this issue, a new external-internal composite spinning technology is proposed. External and internal spinning are to handle the necking-in zone and flanging zone, respectively, of the Ω-sectioned profile of the ring. During the spinning process, roller trajectory is crucial to determine whether the ring can be formed successfully. Therefore, two types of roller trajectory were proposed: circular-straight and involute, the effect of which on the forming were compared via finite element simulation. The results indicate that the involute roller trajectory tends to produce a lower wall thickness reduction and improve the anti-wrinkling ability of the blank. The involute roller trajectory and its parameters were then determined. Then the process parameters were studied. With the increase of the mandrel speed, roller feed ratio, and roller nose radius, lower wall thickness reduction of the blank was obtained, while the wrinkling factor increases rapidly. According to these results, a process scheme is designed, with which successful experiments have been performed. The external-internal composite spinning technology shows great capability on forming the thin-walled complex-sectioned ring part.