Research of Lubrication Model and Surface Quality in Cold-Rolling Copper Alloy Using O/W Emulsions

A theoretical model for cold-rolling copper alloy in mixed lubrication regime was developed based on the average volume flow model and asperity flattening model. The developed scheme was able to calculate oil concentration λd at any point within work zone, lubricant pressure, contact area ratio and film thickness ratio with different oil viscosity, pass reduction and the initial oil concentration λds. According to the lubrication model, for getting good lubrication and cooling effect of emulsions in rolling process, the rolling oil viscosity was selected in the range from 40 mm2/s to 50 mm2/s, the pass reduction about 30% and the initial oil concentration λds of emulsion in the range from 0.02 to 0.05. For verifying the lubrication model, the last nonseizure load was tested by the four-ball tests to confirm oil viscosity and initial oil concentration, and the rolled copper alloy surface topographies were analyzed to confirm pass reduction. The results show that the calculation data agree well with the measured data from experiment. They provide technical references for selecting rolling process parameters and emulsions.