摘要
针对材料为20Cr的某电机齿轮在冷挤压成形时内齿齿顶面上出现的裂纹缺陷,基于DEFORM-3D对其冷挤压过程进行了模拟,研究了其裂纹形成机理。有限元结果表明,内齿的金属流动速度小于中部及下部外齿的流动速度,内齿齿顶面上齿根处的金属流动速度最小,此处流动最不均匀,易产生应力集中;对齿面的最大主应力及损伤分布进行了分析,得出在内齿齿顶面上,中部及距离下端面1 mm左右的位置应力集中最明显,拉应力较大且大于材料抗拉强度,损伤值也较大且大于临界损伤值,会产生裂纹,与实际情况相符合。通过改变凹模入模角来控制成形缺陷情况,当凹模入模角为23°时,齿根处拉应力下降,损伤值减小,投入生产后次品率从原本的50%降为1%。
Aiming at the crack defects on the teeth top surface of the inner teeth of a motor gear with 20Cr during cold extrusion,the cold extrusion process was simulated to study the crack formation mechanism based on DEFORM-3D.The finite element results show that the metal flow velocity of the inner teeth is smaller than that of the middle and lower outer teeth,the metal flow velocity at the teeth root on the teeth top surface of the inner teeth is the smallest,where the flow is the most uneven and the stress concentration is easy to occur.The maximum principal stress and damage distribution of the teeth surface were analyzed,it is concluded that the stress concentration is the most obvious at the middle and the position about 1 mm from the lower end surface on the teeth top surface of the inner tooth.The tensile stress is larger than the tensile strength of the material,and damage value is also larger than the critical damage value,and cracks can be generated,which is consistent with the actual situation.The forming defects were controlled by changing the die entry angle.When the die entry angle is 23°,the tensile stress at the teeth root decreases,the damage value decreases,and the defective rate is reduced from 50%to 1%after production.
作者
董文正
王丹
林启权
刘鲜蓉
许小龙
DONG Wen-zheng;WANG Dan;LIN Qi-quan;LIU Xian-rong;XU Xiao-long(School of Mechanical Engineering and Mechanics,Xiangtan University,Xiangtan 411105,China;State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,Changsha 410083,China;Yuhuan Putian Starter Drive Company,Yuhuan 317600,China)
出处
《塑性工程学报》
CAS
CSCD
北大核心
2024年第8期208-215,共8页
Journal of Plasticity Engineering
基金
国家自然科学基金资助项目(52275386)
湖南省自然科学基金资助项目(2023JJ50022)
极端服役性能精准制造全国重点实验室开放课题(Kfkt2022-05)。
关键词
冷挤压齿轮
裂纹缺陷
模具优化
韧性断裂损伤
cold extrusion gear
crack defect
die optimization
ductile fracture damage
