Analysis of friction characteristics during the thread cold rolling process by using a novel single-tooth rolling friction test

The thread cold rolling process is an advanced produce for manufacturing thread parts. During this process, friction between the rolling die and the workpiece significantly influences the deformation process and the quality of the formed thread parts. However, material deformation and contact conditions between the rolling die and workpiece are complex, posing challenges to the study of friction during the deformation process. A single-tooth rolling friction test (STRFT) was proposed to investigate friction properties in the thread cold rolling process and surface morphology of the formed part. Moreover, the effects of friction on material flow behavior and stress distribution characteristics were investigated. Experiments were performed under various lubrication conditions, and finite element simulation was used to calibrate the friction factor. Rolling torque was significantly affected by the friction factor and regarded as the sensitive parameter. The friction factor m was determined as 0.16 under lubrication condition by comparing the torque during the test and the simulation. A larger friction factor increased deformation stress and decreased material flow speed. The bottom of the formed groove under larger deformation stress exhibited greater roughness and more surface defects than the flank.