Design And Flow Field Analysis Of The Air Cooled Structure Of Ultra-high Speed Grinding

Ultra-high speed grinding refers to the liner velocity more than150m/stechnology. Due to its high processing efficiency, well processing quality andmachinability to super hard material, ultra-high speed grinding develops rapidlyin recent years. Grinding produces a lot of heat and the workpiece would besudden-burned easily. In traditional process, sufficient coolant must be suppliedto grinding zone to achieve cooling and lubrication. This method has lowefficiency, high cost, serious pollution to environment, and lower effective ratioof grinding fluid at ultra-high speed grinding because of air barrier. Cooling ofhigh efficiency deep grinding becomes more difficult because of viscosity ofgrinding fluid and characteristics of narrow deep groove. New type of coolingscheme applying to narrow deep groove grinding is needed.Cubic boron nitride (CBN) is a kind of materials with good heat transferperformance, and it could reduce the grinding heat into the workpiece. Then thetemperature in the grinding zone could be decreased sufficiently. The new CBNwheel lays foundation for designing a new type of cooling scheme applied toCBN wheel high efficiency deep grinding.Based on the traditional concept of dry grinding, the scheme of designingair-cooled structure has been proposed. The scheme is suitable for ultra-highspeed grinding especially for high efficiency deep grinding. The process of air cooled wheel structure designing and flow field analysis have been proposed.The main research contents are as follows:(1)Based on the method of studying flow barrier in traditional grinding, theflow distribution of grinding narrow deep groove has been simulated. The wheelthickness, wheel speed, wheel diameter, wheel surface roughness and narrowgroove dimensions, affecting the flow distribution, have been studied. Theprinciple of setting moving heat source has been expounded, which lays thetheoretical foundation for using multi-field coupling to verify the cooling effectof air cooled structure and optimal design.(2) Based on the effect of various parameters of external nozzle on thecooling effect, the theory of designing outlet dimensions of internal air cooledwheel has been proposed. This theory means designing outlet dimensions onwheel and chuck with the goal of maximizing the heat transfer ability. Based onthe basic theory of aerodynamics, the flow channel has been determined. In thecase of determining the flow, this paper designs the turbofan blades to generatethe jet-stream with the goal of maximizing pressure rise.(3) Modeling the environment of air cooled wheel by flow field analysissoftware Fluent has been done, and its cooling effect has been analyzed. Theflow in turbofan blades structure and air outlet structure of air cooled wheelhave been analyzed respectively to provide a reference for next optimal design.