六角頭螺栓於冷鍛成形之新型延性破壞模型

New Ductile Fracture Model of Hexagon Head Bolt in Cold Forging

許昭和(Hsu Chao-Ho) ； 張哲源(Chang Che-Yuan) ； 李文祥(Li Wen-Xiang)

《鍛造》 27卷1期 (2018/04) Pp. 6-11

摘要

六角頭螺栓在冷鍛成形時，常在前方擠伸和鍛粗成形過程中發生破裂，而最常見到的破裂形式為近45度破裂成長趨勢。在圓柱壓縮試驗時，可發現材料受單軸壓縮所發生45度剪應力破壞，故本研究所提出的新型延性破壞模型，是基於最大剪應力所產生之應變能過大而發生延性破壞。將此理論之副程式加入DEFORM的延性破壞模型內，進行六角頭螺栓成形分析，因六角頭螺栓常發生六角頭面45度剪切破裂及前方擠伸的人字紋破裂，此模型可預測前方擠伸破裂趨勢，且成功將模型建立於DEFORM延性破壞資料庫中。

並列摘要

Hexagon head bolt was usually happened to forward extrusion and upsetting fractures in the cold forging, and that fracture growth was the most common 45° directions in the fracture process. When the material was affected with 45° shear stress fracture of uniaxial compression in cylindrical compression test, new ductile fracture model was proposed in this study, it was based to maximum shear stress let the strain energy be too large and that occurrence of ductile fracture. This theory's secondary program was added to the ductile fracture model of DEFORM, and the analysis of the hexagon head bolt forming was carried out, because the hexagon head bolt was often happened hexagon head 45° shear stress fracture and forward extrusion the herringbone fracture, the model can predict the trend of forward extrusion, the model had successfully set up in the DEFORM's ductile fracture database.