Abstract
During sheet metal forming on a doubleaction toggle press, drawbeads on the die binder supply a restraining force which controls the flow of sheet metal into the die. To study the restraining force and the related binder holddown force, an apparatus was built which simulates a drawbead. The apparatus can separate the restraining force into its bending deformation and friction components. From experimental measurements of the appropriate forces a coefficient of friction for drawbeads may be obtained. A comparison of experimental and calculated friction forces shows that Coulomb’s Law (a constant coefficient of friction) satisfactorily represents the friction force in low and medium load ranges. However, Coulomb’s Law breaks down at higher loads. The load at which breakdown occurs depends on interactions among many variables including sheet metal material, lubricant, and surface roughness.
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H. D. Nine:Mechanics of Sheet Metal Forming, D. P. Koistinen and N.-M. Wang, eds., Plenum Press, 1978, p. 179.
W. R. D. Wilson:Mechanics of Sheet Metal Forming, D. P. Koistinen and N.-M. Wang, eds., Plenum Press, 1978, p. 157.
D. Tabor:Proc. Roy. Soc. (London), 1959, vol. A251, p. 378–93.
R. C. Spragg and D. J. Whitehouse:Proc. I. Mech. E., 1970, vol. 185, p. 697.
B. Fogg:Sheet Metal Industries, 1967, vol. 44, p. 478.
S. Fukui et al.:Sheet Metal Industries, 1963, vol. 40, p. 739.
B. Fogg:Sheet Metal Industries, 1976, vol. 53, p. 294–302, p. 304.
N. M. Wang: “A Mathematical Model of Drawbead Forces in Sheet Metal Forming,”Journal of Applied Metalworking, July 1982, vol 2, no. 3, p. 193.
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This and the preceeding paper in this volume on drawbead forces are based on work done in a cooperative program among the General Motors Mathematics and Physics Departments of the Research Laboratories and Fisher Body Division. A previously published paper, “Drawbead Forces in Sheet Metal Forming,”1 described experimental work on deformation and Coulomb’s friction forces. The preceding paper of this set describes an analytical model and results of calculations for deformation and friction forces in drawbeads. This paper gives an expanded experimental study of friction forces extending work to loads where Coulomb’s friction law breaks down. The three papers together give a comprehensive view of the experimental and analytical work on drawbead forces.
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Nine, H.D. The applicability of Coulomb’s friction law to drawbeads in sheet metal forming. J. Applied Metalworking 2, 200–210 (1982). https://doi.org/10.1007/BF02834038
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DOI: https://doi.org/10.1007/BF02834038