Mathematical Representation of Friction in Metal Forming Analysis
As recently stressed by Kalpakjian [1]. Schey [2] and many other authors [3-8] the development is an improved friction model is an important topic in metal farming analysis. In the present study a fresh friction approach is suggested. It connects the friction shear stress not only with the normal stress but also with the relative displacement between tool and workpiece and the relative surface increase. The model presented is based on the physical conception of the friction phenomenon as described by Schey [2.4″], Wanheim, [7] and Dautzenberg [8, 9]. Connections with the well known Coulomb model (T Fr = up) and the so called constant friction model [T Fr = m J F /✓3 and discussed. Theoretical findings are verified with experimental data from different tests. Although a few questions are still open, some progress in technical understanding of friction in forming tools could be achieved.
Friction and Lubrication in Sheet Metal Forming
The type of lubrication regime which occurs in a metal forming operation has a strong influence on the frictional conditions as well as on other important factors such as product surface finish and tooling wear rates. The various types of regimes which can occur are reviewed, together with what is known about their incidence in sheet metal forming operations. In the light of this information it can be seen that the commonly used methods of characterizing friction in analytical models of metal forming processes will often lead to erroneous results. Suggestions for improved methods of characterizing friction are made.
An inlet zone analysis for the lubrication of a drawing process by a rigid-plastic solid
Abstract An upper-bound method is used to model the entrainment of a solid lubricant in a drawing process. The lubricant is treated as a rigid-plastic solid. A semi-empirical equation for the thickness of the lubricant film that will be entrained under ideal fractional conditions is given.