An innovative rotary rolling-forging process for manufacturing fork ring with extreme geometry

Fork ring is a key structural component of rocket fuel tank, which is difficult to be manufactured with high performance and high efficiency because of its extreme geometry and strict performance requirement. This paper proposes an innovative rotary rolling-forging (RRF) process to realize high performance and high efficiency manufacturing of fork ring. Firstly, the principle of RRF process of fork ring is proposed by combining the advantages of ring rolling and rotary forging. Secondly, the interference determination criterion of RRF die and fork ring is established and the effective die parameter windows are determined, and consequently the die design method for RRF of fork ring is proposed. Thirdly, the mechanical model for predicting the metal flow in RRF process of fork ring is developed by slab method and the uneven growth mechanisms of three ribs are revealed. It is found that the lower rib is the most difficult to be formed and its height hardly increases because of the large metal flow resistance. Based on the above results, the design method for preformed billet is proposed to realize the growth control of three ribs. Finally, the experiments of RRF of fork ring are conducted and it is verified that the proposed RRF process of fork ring and corresponding process design method are feasible. [Display omitted] •An innovative rotary rolling-forging process is proposed to realize high performance and high efficiency manufacturing of fork ring.•The interference determination criterion of die and fork ring is established andthe die design method is proposed.•The mechanical model for predicting metal flow is developed and the design method for preformed billet is proposed to realize growth control of three ribs.•A fork ring with diameter of 240 mm, heights of three ribs of 25 mm and thickness of three ribs of 3 mm is manufactured by rotary rolling-forging process.