Abstract:  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. 

Key words: radial precision forging with integrated forming chamber and rifling, wrinkle defect in inner wall, forming mechanism, criterion

摘要： 弹线膛一体径向精锻工艺能同时成形身管的弹膛和线膛，内膛同轴度高，成形效率高，但该工艺成形的身管内壁会产生轴向的褶皱，褶皱在后续锻造中会演化成裂缝，从而严重影响身管的安全性。为了研究内膛褶皱缺陷的形成机理，建立了三维径向精锻有限元模型，设置进给速度、转速、锤头角度、夹持压力等多组工艺参数变量进行了仿真。仿真结果表明，内膛轴向褶皱是在锻造过程的下沉段形成的，其形成机理是由于四锤头之间存在间隙，导致每次锻打时同一截面工件径向发生不均匀变形，使得径向位移产生差异，经过多次锻打累积，内壁相邻节点的径向位移差就形成了轴向褶皱。同时研究表明，锤头角度越大，毛坯厚度越小，毛坯内径越小，则褶皱形成越晚。建立了以减径量为指标的下沉段褶皱成形判据，通过径向精锻实验验证了该判据的正确性。

关键词: 弹线膛一体径向精锻, 内膛褶皱缺陷, 形成机理, 判据