身管弹线膛同锻成形下沉段开裂缺陷影响因素及判断准则研究

Research on Influencing Factors and Judgment Criterion of Cracking Defects in Sinking Section of the Barrel Forged with Chamber and Rifled Bore

为提高径向精锻时身管内膛的加工质量,以弹线膛同锻身管为研究对象,研究其在下沉段部位的开裂现象。通过分析下沉段部位的应力状态发现,毛坯内壁在这一锻造过程中受到周期性变化的轴向拉应力与压应力,且毛坯在该阶段塑性变形较大,容易出现开裂,研究了不同工艺参数的变化对下沉段部位应力三轴度(即静水压力与等效应力比值)的影响。选用了2种含有应力三轴度成分的断裂准则对身管毛坯在下沉段的开裂现象进行研究,结合锻打试验和有限元仿真结果确定了可加工性曲线作为身管下沉段开裂现象的判断准则。

The radial forging process for both chamber and rifled bore was used to improve the coaxiality of rifled bore,which can effectively solve the problem of coaxiality difference between the two and greatly reduce the processing procedures.In order to improve the surface quality of chamber,the cracking defects in the sinking section was studied.By analyzing the stress state of the sinking section,it is found that the inner surface of the blank was subjected to periodically changing axial tensile and compressive stresses during radial forging process,and the blank was plastically deformed at this stage and is prone to cracking.By changing the process parameters,the influence of the changes of different process parameters on the stress triaxiality of the sinking section was studied.Aiming at the cracking defects in the sinking section,three fracture criteria containing stress ratio components were selected to study the cracking defects.Combining the forging test and finite element simulation results,a formability curve was selected as the criterion for judging the cracking defects of the sinking section of the barrel.