Effects of process parameters on friction in cold strip rolling

Effects of process parameters on friction in cold strip rolling process has been experimentally studied in this thesis. The prime objective is to examine the major parameters affecting the cold rolling process with and without lubricants. This objective has been reached by breaking the problem into four components as follows: (i) the roll pressure and the interfacial shear stress; (ii) the forward slip and the coefficient of friction; (iii) the process parameters, namely the reduction, entry thickness, roll speed, surface roughness, viscosity, and material strength; and (iv) the evaluation of 14 lubricants on the loads on the rolling mill.;Specifically, the following aspects of the problem have been examined.;A varying coefficient of friction through the roll contact arc has been determined through pressure sensitive pin technique. The effects of shimming the pins on their readings and the repeatability of the pin data have been investigated. The accuracy of the pin technique has been examined through comparing the pin readings, transducer data, and the predictions of a one-dimensional model.;In general, the repeatability of the radial pin data is within ;The pressure sensitive pin data are substantiable, within 19% when the roll forces and the torques from the pin data are compared with those measured from the transducers.;It has been demonstrated that the one-dimensional model can predict pressure distributions close to those from the pressure sensitive pin measurements.;Six formulae, commonly used to predict the coefficient of friction from forward slip measurements of a rolling process, have been evaluated according to forward slip measurements and coefficient of friction data from the pressure sensitive pin technique. Essentially, this part bridges the industrial constant coefficient friction approach from forward slip measurements with the academic varying coefficient of friction strategy through the pressure sensitive pin technique.;A systems analysis has been made regarding the effects of all potentially important parameters on friction in cold rolling. Based on this analysis, the effects of six parameters have been identified of most importance and experimented with over representative ranges.;It has been indicated that the amount of oil entrapped in the roll gap is a leading factor for the changes in the forward slip measurements as the process parameters vary.;A dimensional analysis has been made to organize the results of the effects of process parameters on forward slip measurements.;Laboratory evaluations of 14 commercially significant lubricants for cold rolling of aluminum have been carried out from roll force reductions. The roll forces with ester synthetic base with or without additives decrease as the rolling process proceeds, while the forces with other base oils slightly increase when additives are not used and decrease when additives are employed.;The information provided above may be used in cold rolling modelling. In mathematical modelling, one of the boundary conditions is given in the form of coefficient of friction. This coefficient has been shown to vary from the entry to the roll gap to exit. As well, it is a strong function of the geometry, material and process parameters.