Investigation of the Lubrication Influence on Single-phase and Multi-phase Ironing Processes

The ironing process in the cold conditions is frequently accompanied by the high contact pressures and local loading of tools, especially in the multi-phase processes. In such conditions, lubrication has a decisive influence on the successful forming. Absence of lubricant would lead to direct contact of the thin sheet and the tool (die) what would consequently cause the disturbance of the forming process stability; frequently the process would be hindered. Lubrication, as a measure for decreasing the harmful influence of friction at the contact surfaces, enables increase of the deformation and drawing degree. In that sense, experimental investigations were conducted of influence of various types of lubricants on the single-phase and multi-phase ironing processes. The corresponding tribological model was adopted, which is based on sliding of the thin sheet strip between the two side contact elements, which are ironing it. The tribological model was realized according to original experimental device. The variation of the drawing (tensile) force, contact pressures and the friction coefficient were monitored for each type of lubricants, in the single-phase and the three-phase ironing conditions, at the constant sliding speed. In that way, the estimates of each individual lubricant was done. The objective of this research was to compare the tested lubricants from the aspect of their quality and applicability in the ironing processes.