New Method of Determining the Optimal Interference Level in Cold Expansion of Holes Based on Mandrel Extrusion Force

doi:10.3901/JME.2025.24.129

Abstract

Abstract: The cold expansion process of holes has been widely used in aviation, railways, automobiles and other fields to im-prove the fatigue life of fastening holes. The strengthening mechanism of cold expansion is to introduce circumferential residual compressive stress to reduce the average alternating stress around the hole. In order to overcome the short-comings of present method in determining the optimal interference level, such as high cost, time consuming, poor operability, and large errors, the present work proposed a new method based on the mandrel extrusion force to determine the optimal interference level. To achieve the above objectives, the present work employed a thick walled cylindrical mechanical model to build the relationship between the extrusion force of the mandrel and the residual stress around the hole. By using a conical mandrel combined with a slotted bush with a slope, a continuous extrusion force-interference level curve was obtained, and the reduction amount of slope of the extrusion force-interference level curve was proposed as a parameter to determine the optimal interference level. In order to verify the effectiveness of the above method, three cold expansion finite element models of AL-7050 holes with different specifications were established. The predicted optimal interference level of cold expansion of holes with different specifications agreed well with relevant experimental data. The present work provided a simple, fast and effective method of determing the optimal interference level of cold expansion holes with different specifications.

Key words: holes, cold expansion, residual stress, extrusion force, interference level

CLC Number:

V261

YAN Wuzhu, WANG Yaowei, LI Zhen, CHEN Xifeng, WANG Xing, ZHANG Zhiyuan. New Method of Determining the Optimal Interference Level in Cold Expansion of Holes Based on Mandrel Extrusion Force[J]. Journal of Mechanical Engineering, 2025, 61(24): 129-138.

References

[1] 孙暄,王珉,许洪昌,等. 孔的开缝衬套冷挤压强化技术[J]. 机械制造,1998(1):22-24. SUN Xuan,WANG Min,XU Hongchang,et al. Split sleeve hole cold expansion technique[J]. Machinery,1998(1):22-24.
[2] PUCILLO G P. The effects of the cold expansion degree on the fatigue crack growth rate in rail steel[J]. International Journal of Fatigue,2022,164:107130.
[3] 王燕礼,朱有利,曹强,等. 孔挤压强化技术研究进展与展望[J]. 航空学报,2018,39(2):6-22. WANG Yanli,ZHU Youli,CAO Qiang,et al. Progress and prospect of research on hole cold expansion technique[J]. Acta Aeronautica et Astronautica Sinica,2018,39(2):6-22.
[4] 曹增强,胡朝阳,甘学东,等. 小边距孔的压合衬套强化工艺研究[J]. 机械强度,2016,38(5):1093-1098. Cao Zengqiang,HU Zhaoyang,GAN Xuedong,et al. The research of bushing strengthening process on short edge-margin hole[J]. Journal of Mechanical Strength,2016,38(5):1093-1098.
[5] ABDELKADER D,ABDELGHANI B,MOSTEFA L,et al. Numerical analysis of plate thickness effect on residual stress distribution around a cold expanded hole[J]. Transactions of Famena,2023,47(3):47-59.
[6] 唐伟,林忠亮,吴保全,等. 孔结构压合衬套冷挤压强化的疲劳寿命试验研究[J]. 航空精密制造技术,2022,58(4):11-15,41. TANG Wei,LIN Zhongliang,WU Baoquan,et al. Test study on fatigue life of cold extrusion strengthening bushings for hole structure[J]. Aviation Precision Manufacturing Technology,2022,58(4):11-15,41.
[7] LIU Jun,WU Henggui,YANG Jinjie,et al. Effect of edge distance ratio on residual stresses induced by cold expansion and fatigue life of TC4 plates[J]. Engineering Fracture Mechanics,2013,109130-109137.
[8] 董卫萍,高飞,邢欣,等. 开缝衬套冷挤压强化工艺对7050铝合金孔连接结构疲劳寿命的影响[J]. 工具技术,2021,55(12):68-72. DONG Weiping,GAO Fei,XING Xin,et al. Effect of cold extrusion strengthening technology of split-sleeve bushing on fatigue life of 7050 Al alloy hole connection structure[J]. Tool Engineering,2021,55(12):68-72.
[9] GOPALAKRISHNA H,MURTHY N H,KRISHNA M. Cold expansion of holes and resulting fatigue life enhancement and residual stresses in Al 2024 T3 alloy- An experimental study[J]. Engineering Failure Analysis,2010,17(2):361-368.
[10] 鲁世红,高越,李大川. 开缝衬套冷挤压强化技术研究进展[J]. 锻压技术,2021,46(1):1-9. LU Shihong,GAO Yue,LI Dachuan. Research progress of split sleeve cold expansion strengthening technology[J]. Forging & Stamping Technology,2021,46(1):1-9.
[11] 刘莉,何庆芝,瞿履和. 螺接接头最优干涉配合问题的研究[J]. 航空学报,1989(12):640-644. LIU Li,HE Qingzhi,QU Lühe. Studies on the optimization of the interference fit of a bolt joint[J]. Acta Aeronautica et Astronautica Sinica,1989(12):640-644.
[12] 计欣华,邓宗白,鲁阳,等. 工程试验力学[M]. 北京:机械工业出版社,2007. JI Xinhua,DENG Zongbai,LU Yang,et al. Engineering experimental mechanics[M]. Beijing:China Machine Press,2007.
[13] HAKIM A B,HACÈNE T,KHALED B. Analytical solution of aluminum alloy plates with holes subjected to cold expansion with reverse yielding[J]. J. Pressure Vessel Technol,2021,143(4):041302-041312.
[14] Feng Feng,ZHAO Zirui,WANG Zibiao,et al. A calculation method for residual stress of cold expanded hole based on measured springback[J]. Measurement,2023,218:113162.
[15] 闫五柱. 压合衬套的安装方法及结构件:中国,CN112077564B[P]. 2022-07-29. YAN Wuzhu. Installation method and structural parts of bushing:China,CN112077564A[P]. 2022-07-29.
[16] 王耀伟,闫五柱,梁淑静. 一种新型压合衬套冷挤压工艺研究[J]. 航空制造技术,2024,67(10):107-114. WANG Yaowei,YAN Wuzhu,LIANG Shujing. A novel cold expansion technology with forcemate bushing[J]. Aeronautical Manufacturing Technology,2024,67(10):107-114.
[17] 黄宏,赵庆云,刘风雷,等. 孔强化对7050-T7451铝合金疲劳寿命的影响[C]//2015年全国失效分析学术会议论文集. 北京:中航工业北京航空制造工程研究所,2015:486-489. HUANG Hong,ZHAO Qingyun,LIU Fenglei,et al. Effect of strengthened hole on the fatigue life of 7050 T7451 aluminum alloy[C]//Proceedings of the 2015 National Conference on Failure Analysis. Beijing:Beijing Avic Aviation Manufacturing Engineering Research Institute,2015:486-489.
[18] 卢浩,魏永合,江晓宇,等. 孔的开缝衬套冷挤压强化工艺研究[J]. 航空制造技术,2024,67(21):98-105. LU Hao,WEI Yonghe,JIANG Xiaoyu,et al. Study on cold extrusion strengthening technology of split sleeve[J]. Aeronautical Manufacturing Technology,2024,67(21):98-105.
[19] 王强,赵勇,倪孟龙. 高干涉量压合衬套强化铝合金孔结构的疲劳性能[J]. 机械工程材料,2020,44(7):46-50. WANG Qiang,ZHAO Yong,NI Menglong. Fatigue properties of aluminum alloy hole structure strengthened by high interference fit bushing technique[J]. Materials for Mechanical Engineering,2020,44(7):46-50.
[20] SHARIFFUDIN A K,KARUPPANAN S,PATIL S S. Finite element analysis of residual stress in cold expanded plate with different thickness and expansion ratio[J]. IOP Conference Series:Materials Science and Engineering,2017,257(1):12-17.
[21] DEY M K,KIM D,TAN H. Finite element parametric study of the split sleeve cold expansion on residual stresses and pulling force[J]. Proceedings of the Institution of Mechanical Engineers,Part C:Journal of Mechanical Engineering Science,2022,236(5):2447-2461.