Numerical Simulation Of Internal Two-Phase Flow For Effervescent Atomizer And Experimental Study On MQL Machining Performances

In the metal cutting industy, cooling lubricants are one of the most frequently used agents. They help to achieve a prescribed result in terms of cutting temperature,tool life,cutting effect and surface finish. These days, it is required to decrease the consumption of cutting fluid and use chlorine-free cutting fluids for the conservation of the global environment. Disposal cost of the waste cutting oil is increasing. In addition, regulaition for the usage of cutting oils are being enforced. Therefore, from the environmental and economical points of view, green cutting attracts attentions and has been investigated vigorously.In minimum quantity lubrication (MQL) machining, a small amount of biodegradable lubricant is sprayed to the cutting point with compressed air, which provide lubrication and cooling. This paper devise a MQL cutting system which based on the effervescent atomization technology, and simulate the intermal two-phase flow of effervescent atomizer using FLUENT code. Then through the drilling test of 45 steel and ZL107 Al-Si alloy under MQL condition,this paper also study the machining performance of HSS tool.The internal two-phase flow model for effervescent atomizer is constructed based on effervescent atomization principle.Results indicated that there are three regimes of the two-phase flow inside the discharge orifice, one is bubbly fow ,another is annular flow while the other is the intermittent flow. The flow patterns transfered from bubbly flow to intermittent flow and then to annular flow with decreasing of the water flow rate or increasing of the gas to liquid mass ratio (GLR).The cutting performances of the HSS tools for different materials under MQL cutting condition were studied by measuring the tool wear and cutting force directly. Experiment researches for the wear forms,tool lives,cutting forces,etc.on HSS cutting tools during the cutting process,and the comparisons with dry cutting tools were carried out by large numbers of drilling tests for different materials. The variation of the tool wear, cutting forces and built-up edge forming under different machining operations were obtained, and accordingly the applicable scopes and cutting conditions for HSS cutting tools were acquired,which provides an effective way to enlarge the application ranges of HSS tools,reduce tool wear, extend tool life,decrease cutting forces and chip adhesion,improve dimensional precision and machining quality,increase machining efficiency.The MQL flow which is transfered in the form of droplet in air penetrates in the cutting zone directly, and it acts in three different ways, that is, cooling tool and workpiece, lubricating and removing the chips. The efficiency of a MQL flow in relation to a conventional emulsion coolant has been assessed, MQL technique does provide advantages in comparison to conventional wet cutting in terms of lower machining costs and equivalent effects and it is an effective and feasible green cutting technology..