Experimental Study of Lubrication Influence in the Production of Hydroformed T-Joint Tubes

Abstract:

THF process is a forming technique that consists of tube deformation by means of hydraulic pressure and punches which guarantee the tube ends feeding and sealing. In the last years, this technique found a large and rapid diffusion thanks to its many advantages with respect to conventional processes: parts weight reduction, tighter dimensional tolerances, lower costs or fewer secondary assembly operations. Besides, many lacks in the process knowledge still represent an obstacle and they are usually bypassed by trial and error methods. Therefore, lot of studies were conducted to better understand the influence of the process parameters, such as pressure path, punch stroke or material behaviour. In this paper, an experimental study of tubular T-joints made of copper manufactured by means of THF process is described. The aim of this work is to analyze the tube-die interface friction condition effects on the final part. In fact, material flow during the process is greatly influenced by the friction conditions between tube and die especially due to the high pressure acting inside the tube. Different lubrication types were considered: dry, oil, Teflon, Teflon with oil, Teflon spray and Graphitic oil. Two different experimental campaigns were performed in this investigation. The first one was carried out in order to estimate the lubricant friction coefficients using a Pin on Disk tribometer. The second one was performed to study the effects of the lubrication on the process and the tests were conducted hydroforming T-joints under the different lubrication conditions considered. The collected data allowed to identify how the different lubrication conditions affect the final workpiece geometry. Moreover, a critical aspect of the process related to the tube wrinkling was identified and a solution was proposed.

• Periodical: Key Engineering Materials (Volumes 410-411)
• Pages: 15-24
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.410-411.15
• Online since: March 2009
• Authors: Antonio Fiorentino, Elisabetta Ceretti, Attanasio Aldo, Dario Braga, Claudio Giardini
• Keywords: Friction, Lubrication, Pin on Disk, T-Joint, Tube Hydro Forming

References

[1] S.H. Zhang: J. of Materials Processing Tech, Vol. 91 (1998), pp.236-244.

[2] L.H. Langa, Z.R. Wang, D.C. Kang, S.J. Yuan, S.H. Zhang, J. Danckert, K.B. Nielsen: J. of Materials Processing Tech, Vol. 151 (2004), pp.165-177.

[3] S. H. Oh, B.H. Jeon, H.Y. Kim and J.B. Yang: J. of Materials Processing Tech., Vol. 174 (2006), pp.42-45.

[4] P. Ray and B.J. Mac Donald: J. of Materials Processing Tech., Vol. 47 (2005), pp.1498-1518.

[5] H. Sofuoglu and J. Rasty: Tribology International, Vol. 32 (1999), pp.327-335.

[6] M.P. Sutcliffe, R. Combarieu and P. Montmitonnet: Wear, Vol. 257 (2004), pp.1071-1080.

[7] G. Ngalile, S. Jaeger and T. Altan: J. of Materials Processing Tech., Vol. 146 (2004), pp.116-123.

[8] H. Cho and T. Altan: J. of Mat. Processing Tech., Vol. 170 (2005), pp.64-70.

[9] Y.C. Lam, S. Khoddam and P.F. Thomson: J. of Processing Tech., Vol. 83 (1998), pp.62-71.

[10] E. Yoon, H. Kong, O. Kwon and J. Oh: Wear, Vol. 203-204 (1997), pp.341-349.

[11] M. Ahmetoglu, T. Altan: J. of Materials Processing Technology, Vol. 98 (2000), pp- 25-33.

[12] F. Klocke, H.W. Raedt: Int. J. of Refractory Metals and Hard Materials, Vol. 19 issues 4-6 (2001), pp.495-505.

[13] A. Attanasio, A. Fiorentino, E. Ceretti and C. Giardini: American Institute of Physics, Vol. 907 (2007), pp.275-278.

[14] P. Bortot, E. Ceretti and C. Giardini: J. of Mat. Proc. Tech., Vol. 203 (2008), pp.381-388.

[15] E.R. Booser: Tribology data handbook (CRC Press, New York).