A Certain Number Fundamental Research On Minimum Quantity Lubricant High Speed Grinding

Grinding as an important method, a unique way so that the machined surface canachieve a higher quality, is usually used for semi-finishing and finishing link. With thedevelopment of science and technology, a variety of high-speed grinding andultra-precision method has become the development trend, In order to reduce thephenomenon of thermal burns and cracks, we need to adopt more scientific coolingsystems, so as to achieve a higher mill cut quality.At present, pouring cooling is primarily used in the grinding cooling field, and ina few cases using dry grinding, but these two methods have inevitable shortcomings.Casting cooling is not only waste resources but also pollute the environment, and onlya very small part of the grinding fluid penetrated into the grinding zone, and thatcannot give full play to the cooling effect. And a large number of casting grinding fluidwould produce fluid dynamic effect on wheel spindle and the workpiece. Dry grindingis a processing method that does not use any coolant, this method can easily result insurface thermal burns which serious impact on the integrity of the workpiece surface.In this case, the micro-cooling and lubrication (minimum quantity lubricant, referred toas the MQL) MQL cooling method which mixture a small amount of grinding fluidwith high-pressure gas came into being, then spray to the grinding zone in the form ofaerosol, so that the grinding fluid would full absorb the heat of the grinding zone, andwill not cause pollution and waste resources, and thus become a very important methodin the grinding cooling field. In this paper, study the high speed grinding of MQLthrough the following sections.In order to prove minimum quantity lubricant possess advantage compare withtradition grinding, firstly, we study grinding fluid field in the grinding area in the wayof pouring cooling lubrication.Based on the hydrodynamic pressure theory, establisheda smooth mathematical model of the grinding area in the flow field of the traditionalcasting method and consider the grinding wheel and workpiece of the real surfacemorphology of rough contact area of the flow field model, and apply the multi-grid method to get the numerical solution of smooth model, and the rough solution of themodel is consistent to the smooth solution of the model. The calculated results showthat the larger the wheel speed, the greater pressure of grinding fluid hydrodynamic inthe contact area; the wheel diameter almost no effect on the hydrodynamic pressure ofthe contact zone; the smaller the minimum clearance between the wheel and workpiece,the greater pressure in the grinding zone hydrodynamic. The analysis shows that thewheel speed and the minimum clearance between the wheel and workpiece is animportant factor affecting the hydrodynamic pressure in the grinding zone; thecalculation of the fluid speed show that wheel speed is play an important role in thegrinding zone fluid flow, while the minimum clearance between the grinding wheeland the workpiece and the diameter of the grinding wheel hardly affects the fluid flowrate of the grinding fluid. The above numerical calculation values that the existing ofhydrodynamic pressure in the casting cooling lubrication methods generate anadditional radial force, which will have a negative impact on the machining accuracyand the precision of machine tools.Secondly, on the basis of above conclusions, we do a research under theapplication of MQL in grinding. The process of grinding fluid effect is analyzedtheoretically and MQL is demonstrated that can be achieved. Through the processingmethods, it can be achieved or better than the effort of traditional grinding. We do aresearch of how the grinding fluid enter the grinding zone and calculate the speed ofthe grinding fluid breaking through the barrier layer of gas and the fluid direction ofavoiding reverse the air flow and an effective amount of grinding fluid. Additionallychoose the grinding parameters,45steel for grinding materials, compared by theexperiment, on the condition of the traditional grinding fluid supply grinding,grinding trace cooling lubrication and dry grinding of three cases, find the differencesand reasons of the output parameters (surface roughness, microstructure, grinding force,grinding heat), in order to demonstrate MQL can be applied.Once again, based on the premise of high speed grinding, taking Cr12asgrinding objects, we do a research about how the parameters of MQL affect theintegrity of the surface of workpiece. Through the orthogonal experiment of the processing quality, take grinding heat, grinding force, the degree of work hardening,surface roughness and morphology as an indicator, the significant problems of how themain parameters in the MQL cooling method affect high-speed grinding has beendemonstrated. We explored some combinations of parameters and optimize thegrinding process, and the regression equation is established.Finally, cooling and lubricating fluid applied in MQL cooling method hasbeen studied deeply. Add nanometer solid particles into MQL lubrication fluid mediumand produced nanofluids, and then using high-pressure jet way to provide lubricationand cooling for the grinding. Elaborated on nanofluid heat transfer enhancementmechanism in detail. Focuse on the preparation and components of nano-fluids, alsothe analysis of the measurement and influencing factors of thermal conductivity ofnanofluids. Take nanofluid as cooling medium of MQL grinding zirconia ceramic, tocarry out an experimental study. Through the analysis of grinding force, grinding forceand grinding temperature, MQL lubrication fluid by adding nanometer solid particlescan improve the cooling and lubricating properties.