Research On The Related Technologies Of Superheated Water Vapor As Coolant And Lubricant In Green Cutting

Cutting fluids are usually employed to reduce cutting forces, cutting temperature, and tool wear, to improve the surface finish and to increase the productivity. In the machining of difficult-to-cut materials, some classes of extreme pressure additives are used to enhance the performance of cutting fluids. However, conventional cutting fluids and additives are harmful to health, and the waste liquid may pollute the environment. Along with the implementing of sustainable development strataegy, green cutting has become one of the trends in the field of manufacturing. Because of broad source, without pollution, no need to disposal and so on, it has important theory significance and practical value to research the related tecnologis of green cutting with surperheated water vapor as coolant and lubricant, especially in the machining of difficult-to-cut materials.Firstly, the action mechanism of the surperheated water vapor as coolant and lubricant is discussed, based on reviewing the researhes on the green cutting and cutting technologies of typical difficult-to-cut materials. By analyzing the capillary theories and the stress distributing in tool-chip interface, it is proposed that a conical capillary and the space condition of coolant and lubricant penetrating the capillary, that is the diameter of the coolant and lubricant molecule mut be less than that of the capillary. The flow velocity, the flow rate and the temperature distribution are obtained by using the boundary layer theory, and then the cooling and lubricating action of water vapor were analyzed. These are the theorical foundations for the cutting experiments with surperheated water vapor as coolant and lubricant.Secondly, the superheated water vapor feed systems for single and multi-michine tool are developed for researching the action performance of superheated water vapor as coolant and lubricant in metal cutting. These systems are formed by affusion, heating, control, feed vapor and so on, and can generate.the superheated water vapor of pressure at 0.2MPa and temperature at 130℃. And then the cutting experimental system is built on a lathe.Thirdly, using superheated water vapor as coolant and lubricant, the results of the tool wear experiments to cut 45 steel show that the tool wear was reduced comperaed to dry cutting and cutting fluids. The analysis to the components and shape adhered to the rake face, suggests that the capillary mentioned above was subsistent. Applying superheated water vapor and other 4 kinds of industrial gas as coolant and lubricant, the results of cutting 45steel and austenitic stainless steel 1Cr18Ni9Ti show that the cutting force, cutting deformation and cutting temperature were all decreased, the machined surface was improved and the chip breaking was promoted by using superheated water vapor. And the experimental expressions of cutting force and cutting temperature were fitted. The relationship of exponents and coefficients with cutting parameters was discussed. Then according to these experimental results, the green perfomence was evalued by the multi-hierachical fuzzy synthesis evaluation method.Finally, to achieve the green cutting of difficult-to-cut materials, the cutting experiments were carried out on 3 kinds of tapical difficult-to-cut materials, austenitic stainless steel 1Cr18Ni9Ti, titanium alloy TC4 and Ni-base super alloy GH4169, by using superheated water vapor as coolant and lubricant. The results showed that the cutting force, cutting deformation and cutting temperature were all decreased, the machined surface was improved and the chip breaking was promoted by the using superheated water vapor. And then the experimental expressions of cutting force and cutting temperature and the Taylor formula of tool wear were fitted. The relationship of exponents and coefficients with cutting parameters was discussed. The friction marks were conical on the rake face. The tool wear causes were investigated by the SEM analysis. The results implied that the abrasive wears, adhibition and diffusion were alleviated by the application of superheated water vapor as coolant and lubricant.