Optical measurement approach to analyse the tool-workpiece interacting flow of grinding processes

Investigations of the coolant flow within a running grinding machine are carried out to examine the flow behaviour of the coolant in interaction with the grinding wheel and the workpiece. The aim of the investigations is to understand the interaction between fluid, workpiece and tool, to eventually correlate flow dynamics with cooling efficiency. Flow measurements are obtained with Particle Image Velocimetry (PIV), utilising the visualisation of flow structures of the metal working fluid (MWF). Measurements without workpiece provide a fundamental understanding of the MWF-tool interaction, i.e. the flow deflection and entrainment of the MWF with the tool. A limitation of the MWF entrainment into the contact zone occurs for higher inflow velocities, indicating a maximum cooling capacity for inflow velocities around 80 % of the circumferential velocity of the tool. To enable the investigation of the MWF-tool-workpiece interaction, an optical transparent workpiece is designed and implemented into the grinding machine. Flow measurements in the decreasing gap between the workpiece and the rotating grinding wheel reveal a deceleration stagnation of the flow before the beginning of the contact zone. As a result, the PIV-based measurements of the time-averaged MWF flow field in the running grinding machine provide the necessary data basis to understand the flow-based cooling mechanisms in grinding processes. For varying inflow velocities, a nearly constant position of the stagnant flow area is measured, confirming the shown results of a maximum useful flow rate.