Measuring the friction coefficient in the case of plastification of metals by elastomers

摘要

The friction measuring apparatus according to O .Pawelski ,which is based on the strip drawing experiment ,is usedto determine friction coefficients in plastic shaping of metals .Byimplementing elastomer inlays into the drawing cheeks the sameprinciple has been applied to the contact between metals andelastomeric media .The plastification of metal by the extremelyshear-weak elastomer is possible ,because it is completelyconstrained with metal ,so that a sufficiently high hydrostaticpressure in the inlay is generated .Elementary theory incombination with FEM showed that the frictioncoefficient ,calculated using only the global static equilibrium offorces ,is in very good approximation with simply the mixture ofthe friction coefficient between metal strip and elastomer and thefriction coefficient between metal strip and drawing cheekweighted with the corresponding contact areas .Drawingexperiments with aluminium 99.5 or steel St 37 and polyurethaneor soft rubber were carried out .The important influence oflubrication and roughness of the metal strip on the frictioncoefficient was investigated.