Improvement of Forming Quality in T2 Copper Tube Bending with a Granular Mandrel

ZHU Yingxia; WANG Lei; YUAN Chen; CHEN Wei; LI Hui

doi:10.3969/j.issn.1674-6457.2025.12.025

PDF(1607 KB)

Journal of Netshape Forming Engineering ›› 2025, Vol. 17 ›› Issue (12) : 241-249. DOI: 10.3969/j.issn.1674-6457.2025.12.025

Copper Alloy Forming

Improvement of Forming Quality in T2 Copper Tube Bending with a Granular Mandrel

ZHU Yingxia^*, WANG Lei, YUAN Chen, CHEN Wei, LI Hui

Author information +

History +

Abstract

The work aims to investigate the effect of granular mandrel filling on the forming quality of T2 copper tubes in numerical control (NC) rotary draw bending, to analyze its efficacy on controlling cross-sectional collapse, suppressing wall thinning, and reducing damage, thereby improving the forming accuracy and service reliability of bent components. A finite element model of the granular mandrel based on the Drucker-Prager constitutive model was established and validated through experiments. The effects of the granular mandrel on the cross-sectional collapse rate, wall thinning rate, and damage distribution during the tube bending process were systematically studied. A comparative analysis was conducted against three other conditions of no mandrel, a rigid mandrel, and a polyethylene (PE) mandrel. The average cross-sectional collapse rate with the granular mandrel (9.94%) was significantly lower than that without a mandrel and stabilized gradually with the increasing bending angle. The average wall thinning rate with the granular mandrel (8.55%) was notably lower than that with the rigid (10.18%) and PE mandrels (10.47%). The maximum damage value obtained with the granular mandrel (0.88) was also lower than that with the rigid (0.93) and PE (0.90) mandrels. The granular mandrel achieves an optimal balance among cross-sectional stability, wall thickness uniformity, and damage control, demonstrating overall superior performance compared to traditional rigid and PE mandrels. Its flexible filling medium becomes progressively compacted during bending, providing effective internal support while mitigating stress concentration. This offers a reliable new solution for high-precision tube bending manufacturing.

Key words

granular mandrel / tube bending / cross-sectional collapse / wall thinning / damage

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

ZHU Yingxia, WANG Lei, YUAN Chen, CHEN Wei, LI Hui. Improvement of Forming Quality in T2 Copper Tube Bending with a Granular Mandrel[J]. Journal of Netshape Forming Engineering. 2025, 17(12): 241-249 https://doi.org/10.3969/j.issn.1674-6457.2025.12.025

References

[1] 白嘉瑜, 焦华. 化学氧化法制备表层含CuO的超细铜线及其电化学腐蚀行为研究[J]. 焊管, 2024, 47(2): 87-94.
BAI J Y, JIAO H.Preparation of Superfine Copper Wire Containing CuO by Chemical Oxidation Method and Electrochemical Corrosion Behavior[J]. Welded Pipe and Tube, 2024, 47(2): 87-94.
[2] WU L, MA A L, ZHANG L M, et al.Intergranular Erosion Corrosion of Pure Copper Tube in Flowing NaCl Solution[J]. Corrosion Science, 2022, 201: 110304.
[3] YANG J, HE Y, ZHANG X H, et al.Improving the Electrical Conductivity of Copper/Graphene Composites by Reducing the Interfacial Impurities Using Spark Plasma Sintering Diffusion Bonding[J]. Journal of Materials Research and Technology, 2021, 15: 3005-3015.
[4] 周文坤, 刁健帅, 张敏, 等. 氧化物陶瓷颗粒对铜基熔覆层组织演变及性能的影响[J]. 焊管, 2024, 47(2): 63-69.
ZHOU W K, DIAO J S, ZHANG M, et al.Effect of Oxide Ceramic Particles on Microstructure Evolution and Properties of Copper Based Cladding Layer[J]. Welded Pipe and Tube, 2024, 47(2): 63-69.
[5] OUAFIK A, WAHID A, IDIRI M, et al.Mechanical Characterization and Statistical Study of Copper Electrical Wires in an Overhead Line[J]. International Journal on Technical and Physical Problems of Engineering, 2022, 14(2): 261-266.
[6] SINGH G, PANDEY P M.Experimental Investigations into Mechanical and Thermal Properties of Rapid Manufactured Copper Parts[J]. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020, 234(1): 82-95.
[7] JIANG Q, ZHANG P L, YU Z S, et al.A Review on Additive Manufacturing of Pure Copper[J]. Coatings, 2021, 11(6): 740.
[8] GUO X Z, CHENG X, XU Y, et al.Finite Element Modelling and Experimental Investigation of the Impact of Filling Different Materials in Copper Tubes during 3D Free Bending Process[J]. Chinese Journal of Aeronautics, 2020, 33(2): 721-729.
[9] TRONVOLL S A, MA J, WELO T.Deformation Behavior in Tube Bending: A Comparative Study of Compression Bending and Rotary Draw Bending[J]. The International Journal of Advanced Manufacturing Technology, 2023, 124(3): 801-816.
[10] ROEIN M, ELYASI M, MIRNIA M J.Introduction of a New Method for Bending of AISI 304L Stainless Steel Micro-Tubes with Micro-Wire Mandrel[J]. Journal of Manufacturing Processes, 2021, 66: 27-38.
[11] 潘志国, 丁潼, 舒送, 等. 基于芯棒内支撑的管材自由弯曲起皱失稳特性预测研究[J]. 精密成形工程, 2025, 17(8): 180-193.
PAN Z G, DING T, SHU S, et al.Research on the Prediction of Wrinkling Instability Characteristics in Free Bending of Tubes with Internal Mandrel Support[J]. Journal of Netshape Forming Engineering, 2025, 17(8): 180-193.
[12] JIANG J W, GUO X Z, SHEN Y Z, et al.Effect of Bending Radius on Deformation Behavior of H62 Brass Tubes in a less Constrained Free Bending Process[J]. International Journal of Material Forming, 2023, 16(5): 50.
[13] GUO X Z, TAO J, YUAN Z.Effects of Rigid Mandrel and Lubrication on the Process of Elbow Parts by Cold Push-Bending[J]. Advanced Science Letters, 2011, 4(8): 2618-2622.
[14] ZHU Y X, LIU Y L, LI H P, et al.Comparison between the Effects of PVC Mandrel and Mandrel-Cores Die on the Forming Quality of Bending Rectangular H96 Tube[J]. International Journal of Mechanical Sciences, 2013, 76: 132-143.
[15] BAI L, LIU J, WANG Z A, et al.Optimal Design of the Shape of a Non-Ball Mandrel for Thin-Walled Tube Small Radius Cold Bending[J]. Metals, 2021, 11(8): 1221.
[16] SAYAR M A, GERDOOEI M, EIPAKCHI H, et al.Rubber Mandrel and Internal Pressure Effects on Thin-Walled Tube Bending: A Comparative Study[J]. The International Journal of Advanced Manufacturing Technology, 2025, 136(7): 3197-3213.
[17] ELYASI M.Effect of the Internal Pressure in the Rubber Mandrel on the Defects of the Rotary Draw Bending Process[J]. Journal of Mechanical Science and Technology, 2024, 38(3): 1149-1153.
[18] ZHU Y X, LI H, LU X Z, et al.Comprehensive Study on the Effects of Plastic Mandrels on Springback, Crack, and Collapse in Small Radius Bending of Composite Tubes[J]. The International Journal of Advanced Manufacturing Technology, 2025, 138(7): 2955-2973.
[19] DONG G J, ZHAO C C, CAO M Y.Flexible-Die Forming Process with Solid Granule Medium on Sheet Metal[J]. Transactions of Nonferrous Metals Society of China, 2013, 23(9): 2666-2677.
[20] CHEN H, HESS S, HAEBERLE J, et al.Enhanced Granular Medium-Based Tube and Hollow Profile Press Hardening[J]. CIRP Annals, 2016, 65(1): 273-276.
[21] CHEN H, GÜNER A, BEN KHALIFA N, et al. Granular Media-Based Tube Press Hardening[J]. Journal of Materials Processing Technology, 2016, 228: 145-159.
[22] DONG G J, ZHAO C C, PENG Y X, et al.Hot Granules Medium Pressure Forming Process of AA7075 Conical Parts[J]. Chinese Journal of Mechanical Engineering, 2015, 28(3): 580-591.
[23] LIU H, ZHANG S H, CHENG M, et al.DEM Simulation of Bead Packs as Fillers in Thin-Wall Tube Push Bending Process[C]//The 11TH International Conference on Numerical Methods in Industrial Forming Processes: Numiform 2013, Shenyang, China. AIP, 2013: 708-713.
[24] DU B, ZHAO C C, DONG G J, et al.FEM-DEM Coupling Analysis for Solid Granule Medium Forming New Technology[J]. Journal of Materials Processing Technology, 2017, 249: 108-117.
[25] LIU H, ZHANG S H, SONG H W, et al.3D FEM-DEM Coupling Analysis for Granular-Media-Based Thin-Wall Elbow Tube Push-Bending Process[J]. International Journal of Material Forming, 2019, 12(6): 985-994.
[26] LIU H, ZHANG S H, DING Y P, et al.A Simplified Formulation for Predicting Wrinkling of Thin-Wall Elbow Tube in Granular Media-Based Push-Bending Process[J]. The International Journal of Advanced Manufacturing Technology, 2021, 115(1): 541-549.
[27] SONG H W, XIE W L, ZHANG S H, et al.Granular Media Filler Assisted Push Bending Method of Thin-Walled Tubes with Small Bending Radius[J]. International Journal of Mechanical Sciences, 2021, 198: 106365.
[28] 朱英霞, 王匀, 万苗苗, 等. 芯模填充对铜钛复合管绕弯截面畸变和壁厚减薄作用的模拟研究[J]. 航空制造技术, 2020, 63(21): 54-62.
ZHU Y X, WANG Y, WAN M M, et al.Simulation Research on Effect of Mandrel Filling on Section Distortion and Wall Thickness Reduction of Rotary-Draw Bending of Copper-Titanium Composite Tube[J]. Aeronautical Manufacturing Technology, 2020, 63(21): 54-62.
[29] XU Z T, HUANG J H, MAO M Y, et al.An Investigation on the Friction in a Micro Sheet Metal Roll Forming Processes Considering Adhesion and Ploughing[J]. Journal of Materials Processing Technology, 2020, 285: 116790.
[30] 潘颖, 丁雁生, 蔡瑞娇. 颗粒增强复合材料中内应力的细观力学模型[C]//第十五届全国复合材料学术会议论文集. 哈尔滨, 2008: 317-321.
PAN Y, DING Y SH, CAI R J.Mesoscopic Mechanics Model of Internal Stress in Particle Reinforced Polymer Matrix Composite[C]//In Proceedings of the 15th National Conference on Composite Materials, 2008: 317-321.
[31] 孙珊珊, 苏勇, 季顺迎. 颗粒滚动-滑动转换机制及摩擦系数的试验研究[J]. 岩土力学, 2009, 30(S1): 110-115.
SUN S S, SU Y, JI S Y.Experimental Study of Rolling-Sliding Transition and Friction Coefficients of Particles[J]. Rock and Soil Mechanics, 2009, 30(S1): 110-115.