Multi-steps hydroforming technology of small diameter C-shaped metallic seal ring

Hydroforming is an effective way for precision manufacturing of complex thin-walled components of aeroengines. According to the micro size characteristics of thin-walled superalloy C-shaped seal ring components of an aero-engine, a two-steps hydroforming process was proposed. The stress-strain analysis of multi-steps hydroforming process was conducted, and the finite element analysis model of multi-step hydroforming process was established. The impact of process variables, such as the height of the blank forming and the hydraulic loading path, on the forming quality of the seal ring was investigated using numerical simulation and process experimentation. Failure modes, such as the loss of section geometric characteristics, inadequate die attaching, and excessive wall thickness thinning, were also investigated. The process parameters were optimized. The results show that the two-step hydroforming process can achieve accurate forming of a thin-walled C-shaped metal seal ring. By using the optimized process parameters: height of blank forming of 1.0mm, first pass cavity pressure of 140 MPa, second pass cavity pressure of 180 MPa, the high-quality C-shaped seal ring with the degree of blank molding of 93.9%, thinning rate of 10.5% and wall thickness uniformity of 85.5% can be made.