某型号喷管内壁成形缺陷分析及工艺改进

Analysis of forming defects and improvement of forming technology for a certain type nozzle inner wall

某型号喷管内壁为曲母线回转体零件,采用锥形坯料液压成形的工艺方法加工。成形后零件存在大端周圈起皱及小端喉部下方周向环状突起的缺陷,严重影响产品质量。为提高零件型面及尺寸精度,应用PAM-STAMP钣金数值模拟软件对零件的成形过程进行仿真,观察零件成形过程中坯料在模具型腔内的变形过程,并获得了坯料变形过程中的应力应变分布状况。同时,结合材料塑性成形理论分析,找到了该零件成形缺陷产生的原因,即模具型面及间隙设计不合理。进而,根据分析得出的零件变形规律及应力应变分布状况对模具型面进行设计改进,生产出了满足设计图纸要求的零件。数值模拟得到的零件壁厚及型面间隙与实际零件一致。可见,准确掌握零件变形规律,合理设计模具型面及间隙,消除了零件成形缺陷。

The inner wall of a certain nozzle is the revolving parts with curved generatrix,which is hydraulic formed by conical blank.After forming,the part has the defects of wrinkling in the large end and annular protrusion below throat of small end,which seriously affects the quality of products.In order to improve the accuracy of part surface and dimension,PAM-STAMP sheet metal numerical simulation software was used to simulate the forming process of parts,through which the deformation process of blank in the die cavity during the forming process was observed,and the stress and strain distribution during the deformation process of blank was obtained.At the same time,combined with the theory of material plastic forming,the causes of forming defects of the part were found,that is,the design of die surface and clearance was unreasonable.Then,according to the deformation law and stress-strain distribution of the part obtained from the analysis,the design of the die surface was improved,and the part meeting the requirements of the design drawings was produced.The wall thickness and surface clearance obtained by numerical simulation are consistent with the actual parts.It is thus clear that,the forming defects of part can be eliminated by accurately grasping the deformation law of part and reasonably designing the die surface and clearance.