Development of L-sectioned ring for construction machines by profile ring rolling process

Recently, there is an increasing commercial interest in manufacturing rings with a complicated cross-sectional shape directly by a metal forming process instead of by machining. Profile ring rolling is one of the advanced metal forming technologies to manufacture large or small seamless profile rings. Compared with plain ring rolling, profile ring rolling can yield considerable savings in material cost and a shorter cycle time for additional machining. In this study, a profile ring rolling process for producing large-scale profile rings with an L-section for construction machine parts is developed. The manufacturing process of large-scale profile rings with L-section consists of a forging stage and a profile ring rolling stage. In the forging stage, the raw material is formed to initial blanks for profile ring rolling. The forged initial blanks are then formed to the final product shape in the profile ring rolling process, which is designed to occur in a single pass to minimize the cycle time. The design of the blank shape is very important, to enable the design of a profile ring rolling process without forming defects, such as fishtails, underfilling, and distortion of the ring. A finite-element (FE) analysis was performed to optimize the blank ring shape, with the objective of minimizing forming defects. After determination of the initial blank shape, the effects of process variables such as feed conditions of mandrel and axial rolls on the final product shape was investigated to improve the dimensional accuracy. Also, forming experiments were conducted based on the results of the FE analysis. The experimental results were in good agreement with the results of the FE analysis.