An experimental analysis of upset forging of aluminium cylindrical billets considering the dissimilar frictional conditions at flat die surfaces

Original Article

Abstract

Friction plays a major role in all bulk metal forming processes, except in a few isolated cases such as die-less wire drawings, etc. In upset cold forging, the existence of frictional constraints between the dies and the work-piece directly affect the plastic deformation of the latter. When a solid cylinder is compressed axially between the top and bottom platen, the work piece material in contact with their surfaces undergoes heterogeneous deformation resulting in “barrelling” of the cylinder. The friction at the faces of contact retards the plastic flow of metal on the surface and in its vicinity. A conical wedge of a relatively undeformed metal is formed which suffers high strain hardening and bulges out in the form of a barrel. This experimental work has been undertaken to study the bulging effect of aluminium solid cylinders, varying the frictional conditions at the flat die surfaces. Flat dies of different surface finish were produced by different machining processes like grinding, milling, electro-spark machining, and lathe turning and finishing with ‘0’ grade emery paper. Experiments were conducted for two aspect ratios. The radius of curvature of bulge was measured and found to conform to the calculated bulge using experimental data. The calculations are made with the assumption that the curvature of the bulge followed the form of a circular arc. A relationship was established between the various bulge parameters including new hoop strain, hydrostatic stress, geometrical shape factor, and stress ratio factor, considering the dissimilar frictional conditions.

Keywords

Friction Barrelling Hoop strain Hydrostatic stress Stress ratio parameter 

References

  1. 1.
    Johnson W, Mellor PB (1975) Engineering plasticity. Van Nostrand Rehinhold, London, pp 110–114Google Scholar
  2. 2.
    Shaw MC, Avery JP (1980) Forming limits—reliability, stress analysis and failure prevention methods in mechanical design. Century, Chicago, pp 297–303Google Scholar
  3. 3.
    Kulkarni KM, Kalpakjian S (1969) A study of barrelling as an example of free deformation. J Eng Ind—T ASME 91:743–754Google Scholar
  4. 4.
    Schey JA, Venner TR, Takomana SL (1982) Shape changes in the upsetting of slender cylinders. J Eng Ind—T ASME 104:79–83Google Scholar
  5. 5.
    Banerjee JK (1985) Barrelling of solid cylinders under axial compression. J Eng Mater—T ASME 107:138–144Google Scholar
  6. 6.
    Narayanasamy R, Murthy RSN, Viswanatham K, Chary GR (1988) Prediction of the barrelling of solid cylinders under axial compressive load. J Mech Work Technol 16:21–30CrossRefGoogle Scholar
  7. 7.
    Yang DY, Choi Y, Kim JH (1991) Analysis of upset forging of cylindrical billets considering the dissimilar frictional conditions at two flat die surfaces. Int J Mach Tool Manu 31:397–404CrossRefGoogle Scholar
  8. 8.
    Chen FK, Chen CJ (2000) On the non uniform deformation of the cylinder compression test. J Eng Mater—T ASME 122:192–197Google Scholar
  9. 9.
    Gokler MI, Darendeliler H, Elmaskay N (1999) Analysis of tapered preforms in cold upsetting. Int J Mach Tool Manu 39:1–16CrossRefGoogle Scholar
  10. 10.
    Sowerby R, O’Reilly I, Chandrasekaran N, Dung NL (1984) Materials testing for cold forging. J Eng Mater—T ASME 106:101–106Google Scholar
  11. 11.
    Narayanasamy R (2000) Barrelling of solid cylinders during cold forging. REC, Trichy-15, India (unpublished)Google Scholar
  12. 12.
    Narayanasamy R, Pandey KS (1997) Phenomenon of barrelling in Al solid cylinders during cold upset-forging. J Mater Process Tech 70:17–21CrossRefGoogle Scholar

Copyright information

© Springer-Verlag London Limited 2004

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringNational Engineering CollegeK. R. Nagar 628 503India
  2. 2.Department of Production EngineeringRegional Engineering CollegeTrichirappalli 620 015India

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