Forming Mechanism of Axial Wrinkle Defects in Inner Walls of Radial Precision Forged Gun Barrel with Integrated Forming Chamber and Rifling

Integrated radial precision forging forming the chamber and rifling of the gun barrels was efficient, and the radial forged gun barrels had high coaxiality. However, the inner walls of the barrels formed by this processes would generate axial wrinkles. The wrinkles might evolve into a fissure which significantly affected the safety of the gun barrels. To investigate the forming mechanism of wrinkle defects, a three-dimensional radial precision forging finite element model was established, and multiple sets of processing parameters such as feed speed, rotational speed, hammer angle, and clamping pressure were simulated. The simulation results show that the axial wrinkle defects in the inner walls are formed in the sinking zones of the forging processes. The gaps among the four hammerheads cause uneven radial deformation of the workpieces at the same cross-section during each forging, resulting in a difference in radial displacements. After multiple forging accumulations, the radial displacement difference between adjacent nodes on the inner walls forms the axial wrinkles. The paper also shows that the larger the hammer angle, the smaller the blank thickness, and the smaller the internal diameter of the blank, the later the wrinkle formation occurres. A wrinkle-forming criterion was established based on the radius reduction in the sinking zones, and the correctness of the criterion was verified through radial precision forging experiments. © 2023 China Mechanical Engineering Magazine Office. All rights reserved.