Research On The Stainless Steel Precise Turned By Natural Diamond Tool

The austenitic stainless steel has been enjoyed wide use in industry for its excellent mechanical properties, however, it is also known as a typical hardly machinable material for the low thermal conductivity, active reactivity, and short interface between the tool and the chips, high cutting temperature, small modulus of elasticity etc. In this paper, the machining was realized by choosing the tool material and changing the cooling method. The natural diamond is regarded as the ideal tool material for precise machining, but as for turning stainless steel, it is easy to produce wear, which is a difficult problem to solve. Hence it is a significant topic to advance the stainless steel cutting technology.In this paper, the tool material was the natural diamond, the ultrasonic vibration turning was adopted, and the cooling method was the atomization of oil gas. Three types of ultrasonic vibration systems of different frequencies were developed, the ultrasonicators, horns, transducers were developed accordingly. What's more, the atomization system was established. Meanwhile, the traditional turning was also placed to compare with the ultrasonic turning, and the turning results were compared by different cooling methods.Further more, the influence on the tool life and surface roughness could be evaluated by changing the cutting parameters. The mathematical models of the action of the ultrasonic turning and the atomization system were established to explore the mechanism of the lubrication mechanism of the cooling fluid. After reiterative experiments, we summarized the rules and relations among different factors such as the life of diamond turning, tool cutting parameters, material of piece, dimensional accuracy, surface quality, etc.Based on the analysis of the experiments, it follows that:in the ultrasonic vibration turning system, owing to the atomization scheme, the tool wear was decreased significantly, and the surface quality of the work piece was improved. In this type of cooling method, the lubricant film was formed rapidly leading to well lubrication action, which was also enhanced because of the fog drops contained in the cooling draught, reducing friction between the tool and the work piece. In addition, the heat exchange was more enough to control the deformation of the piece. The cooling effect in the cutting area was enhanced by the spraying of ill and gas with big speed and kinetic energy. In the cutting area, due to the carbon dioxide, the liquid volatilized rapidly removing the heat and improving the cooling effect.The combination of the ultrasonic vibration and the atomization system was good to reduce the affinity between the diamond and the stainless steel, protecting the tool. The small cutting force leaded to an improved micro-fracture, and a low cutting temperature which was far lower than the graphitizing temperature. The carbon dioxide and carbon tetrachloride were contributed to reduce the chemical wear of the tool in the abundant carbon cutting area. According to the prior reaction, the carbon dioxide could protect the carbon atom of diamond form diffusing and decomposing effectively under high temperature.The experimental results showed that, when turning 120 faces with diameter 30mm of the stainless steel, the surface roughness Ra was less than 0:15μm, and the wear land of the major flank was less than 5μm. Therefore, increasing amplitude of the tool could improve the surface roughness and wearing capacity obviously. With certain feed amount, cutting speed and cutting depth, by the combination of the ultrasonic vibration and the atomization system, it was feasible to turn the stainless steel precisely by the natural diamond.