Development of Upsetting-Extrusion Type Tribometer for Evaluating Lubrication Coating Performance in Cold Forging

Abstract:

A new upsetting-extrusion type tribometer is developed to investigate the performance of a lubrication coating on the side surface of a billet in multi-stage cold forging. In this tribometer, the lubrication coating on the billet surface is first destroyed by the upsetting process and then evaluated by the extrusion process. The frictional shear factor of the lubrication coating is obtained by plotting the measured extrusion load and the position after the extrusion of a centerline drawn on the billet in advance on the calibration curve obtained by FEM. Experimental results using a zinc phosphate coating and a dry in-place type coating showed that the reduced peak height Rpk is more appropriate than the maximum height Rz to express the effect of the surface roughness of tool on galling generation. When no galling occurs, the frictional shear factor hardly varies with the type of the lubrication coating and the surface expansion ratio. The anti-galling ability of the dry in-place type coating is greatly improved by a two-stage shot blast before the lubrication coating and reaches a level better than the zinc phosphate coating.

• Periodical: Advanced Materials Research (Volumes 966-967)
• Pages: 281-289
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.966-967.281
• Online since: June 2014
• Authors: Zhi Gang Wang*, Shinobu Komiyama, Yasuharu Yoshikawa
• Keywords: Cold Forging, Dry In-Place Type Coating, Galling, Lubrication Coating, Reduced Peak Height, Surface Roughness of Tool, Tribo-Meter

References

[1] N. Bay, A. Azushima, P. Groche, I. Ishibashi, M. Merklein, M. Morishita, T. Nakamura, S. Schmid, M. Yoshida, Environmentally benign tribo-systems for metal forming, Annals of the CIRP. 59 (2) (2010) 760-780.

DOI: 10.1016/j.cirp.2010.05.007

[2] A. T. Male, M. G. Cockcroft, A Method for the Determination of the Coefficient of Friction of Metals under Conditions of Bulk Plastic Deformation, J. Inst. Metals. 93 (1964) 38-46.

[3] S. Isogawa, A. Kimura, Y. Tozawa, Proposal of an Evaluation Method on Lubrication, Annals of the CIRP. 41 (1) (1992) 263-266.

DOI: 10.1016/s0007-8506(07)61200-1

[4] S. Ito, H. Yoshida, S. Isogawa, Y. Doi, K. Dohda, Proposal of Tribosimulator for Forging by Taper Cup Test, Journal of the JSTP. 48 (2007) 303-307. (in Japanese).

DOI: 10.9773/sosei.48.303