Influences on the extended length and performance of push bending for the GH4169 superalloy tube with small bending radius of 1D

Abstract

It is extremely difficult to eliminate the defects like wrinkling, which is generated in the bending of tube with small bending radius. In this thesis, the push-bending process of the GH4169 superalloy tube with a large diameter-thickness ratio of 60 and small bending radius of 1D is studied by numerical simulations and experiments, aiming to eliminate wrinkles on the inside of the tube and obtain enough extended length (e) of straight segment as well as minimal changes in the wall thickness. Three influencing factors, such as the inclined angle (α) at the initial end, the reverse thrust (P) of polyurethane blocks, and the lubrication, are investigated in the simulation. According to the simulations, the proposed experiment is successfully implemented on an independent development of push-bending equipment. The results are in good agreement with the simulation. The optimum parameters for the GH4169 superalloy alloy tube with a large diameter-thickness ratio of 60 and small bending radius of 1D are simulated. And then α is optimized to 45° and P is optimized to 48 MPa. And differential lubrication is used for longer extended length of straight segment and more uniform distribution of wall thickness on both sides of the deformed elbow.