The big-tapered profiled ring disk is a key component of engines for rockets and missiles. A new forming technology, as called spinning-rolling process, has been proposed previously for the high performance, high efficiency and low-cost manufacturing of the component. Blank design is the key part of plastic forming process design. For spinning-rolling process, the shape and size of the blank play a crucial role in process stability, deformation behavior and dimensional accuracy. So this work proposes a blank design method to determine the geometry structure and sizes of the blank. The mathematical model for calculating the blank size has been deduced based on volume conservation and neutral layer length invariance principle. The FE simulation and corresponding trial production of an actual big-tapered profiled ring disk show that the proposed blank design method is applicative. In order to obtain a preferred blank, the influence rules of blank size determined by different deformation degrees (rolling ratio k) on the spinning-rolling process are revealed by comprehensive FE simulations. Overall considering the process stability, circularity of the deformed ring disk and forming forces, a reasonable range of deformation degree (rolling ratio k) is recommended for the blank design of the new spinning-rolling process.

The final quality of complex conical-section rings depends on co-design of multiple processes in forming process chain. In this study, for a complex aeroengine casing ring with a large slope and a flange on its end, a co-design method of the forming process chain is put forward towards the objective of precision forming, which not only proposes a standard process route composed of multiple processes of upsetting, punching, rectangular ring rolling, loose tooling forging and profiled ring rolling, but also presents co-design methods of dies and blanks for all the processes. For profiled ring rolling, a design method of preformed blank that makes the blank and the target conical-section ring have the same axial volume distribution is proposed. By the method, the axial metal redistribution during the process can be alleviated greatly thus improving the forming stability and precision of the ring. Based on the geometric features of designed preformed blank, design methods of blanks and dies for loose tolling forging, rectangular ring rolling, punching and upsetting are proposed sequentially. In view of the key roles of loose tooling forging (manufacturing the preformed blank) and profiled ring rolling on the final quality of the conical ring parts, inherited FE simulations for these two processes are performed to verify the proposed design methods and determine appropriate design parameter. It is demonstrated that the proposed design method has significant advantages in improving forming precision. Besides, a suggestive value 1.5 of the rolling ratio for profiled ring rolling (a key design parameter) is given based on comprehensive consideration of multiple indicators such as ring roundness, deformation uniformity and forming load. The corresponding industrial experiments performed illustrate that a high forming precision of the conical-section aeroengine casing ring is achieved.

A dynamic mechanical model is proposed to describe the complexing actions of all the rolls on the ring during the ultra-large radial-axial ring rolling (RARR) process with four guide rolls. Based on the model, the calculation models for bending moment and normal stress at any section of the ring are deduced by force method. If the maximum section bending normal stress exceeds the yield stress of the ring materials, the ring will be distorted thus leading to the instability of the RARR process. According to this, a plastic instability criterion for the ultra-large RARR process with four guide rolls is developed, based on which a mathematical model to calculate the critical guide force for avoiding plastic instability of ring is obtained. The influence rule of the position of guide roll on the dangerous ring section of plastic instability is revealed, from which it is found the dangerous ring section mainly appears at the radial and axial deformation regions and the contact positions of the guide rolls and ring. The optimized layout of guide roll around the ring in favor of stability is determined to be about α₁ = 61° and α₂ = 119°. The plastic instability criterion is proven to be reliable from the aspects of the critical guide force, the section bending moment and normal stress and the dangerous ring section of plastic instability. Intelligent simulation case studies for the RARR process of ultra-large aluminum alloy ring indicate that the stable forming of the process can be effectively realized by regulating the guide force based on the plastic instability criterion. This work could provide a valuable guidance for the control of guide rolls and the optimization of the ultra-large RARR process with four guide rolls.