304不锈钢棒料连续旋弯低应力精密下料断裂预测

Fracture Prediction of 304 Stainless Steel Bar with Continuous Rotary Bending Low-stress Precision Cropping

低应力下料近净成形方法是制造轴类零部件毛坯的新工艺,具有能耗低、下料效率高及坯料断面精度高等特性,然而其下料机理一直不清晰,难以获取理想的下料工艺参数,因此基于累计损伤理论提出断裂强度因子预测断裂模型进行研究。以304不锈钢为研究对象,将断裂强度因子耦合到连续旋弯低应力下料有限元模型进行断裂预测。通过连续旋弯低应力下料试验,依托断面平整度及下料时间的下料综合评价方法,验证基于断裂强度因子的连续旋弯低应力下料断裂预测数值模拟的正确性。结果表明:基于断裂强度因子断裂预测模型模拟得到的断裂位置位于环状“V”型缺口根部,与下料分离结果保持一致;断面平整度与下料时间随着加载位置提升而降低,当加载位置为L_(1)=5 mm,L_(2)=10 mm能够实现棒料高效精密下料。该下料方法利用断裂强度因子预测断裂模型建立了连续旋弯低应力下料断裂机理,为实现低应力下料工业化奠定理论基础。

Low-stress blanking near-net forming method is a new technology for manufacturing shaft parts blank,which has the characteristics of low energy consumption,high cropping efficiency and high cross-section accuracy.However,its cropping mechanism has always been unclear,and it is difficult to obtain ideal cropping process parameters.Therefore,the prediction fracture model,which is the fracture strength factor,is proposed based on cumulative damage theory.Taking 304 stainless steel as the research object,the fracture strength factor is coupled to the finite element model of continuous rotary bending low-stress cropping to predict the fracture.Through the continuous rotary bending low-stress cropping tests,relying on the comprehensive evaluation index of section flatness and cropping time,the correctness of the numerical simulation of continuous rotary bending low-stress cropping fracture prediction based on the fracture strength factor is verified.The results show that the fracture position simulated by fracture prediction model based on the fracture intensity factor is located at the root of annular V notch,which is consistent with the result of cropping separation.The section flatness and cropping time decrease with the increase of loading position.When the loading position is L_(1)=5 mm and L_(2)=10 mm,high-efficiency and precise cropping of bar can be realized.Based on the theory of fracture intensity factor,the fracture mechanism of continuous rotary bending low-stress cropping is established,which lays a theoretical foundation for realizing the industrialization of low-stress cropping.