Theoretical modeling and simulation of airflow field near grinding wheel

During the grinding, the principal axis drives the grinding wheel to rotate at a high speed, which generates disturbance to the air flows around the grinding wheel. Therefore, a layer of air boundary can be formed on the surface of the working grinding wheel, which is the airflow field. Airflow field not only affects the machining accuracy of the workpiece and the enhanced abrasion of grinding wheel, but also prevents the efficient injection of the grinding fluid into the grinding zone. These processing conditions and lead to the increasing grinding force and rising grinding temperature, deteriorating the processing quality and surface integrity of the workpiece. With higher rotation speed of grinding wheel, the airbond of the air flow will be greater. And the grinding fluid will be harder to break through the airbond and be supplied to the grinding zone. In this study, on the basis of theoretical analysis on the airflow field of grinding wheel, a mathematical model was established, including the internal and external pressure differences of the airflow field, the airbond thickness δ, fluid density ρ, radius R and radius ω. In addition, the changing rules of airflow field along the grinding wheel were studied based on simulation tests. Results demonstrate that the tested airflow field presented the same pressure in concentric circles of the grinding wheel. Along the surface outer normal direction, the pressure value gradually decreased from the outer to the inner space, presenting negative pressure gradient. The velocity of the airflow field around the grinding wheel reduced as the distance from the wheel increased. To a certain thickness, the velocity became zero, which verified the existence of the boundary layer.