Mechanism for increasing cutting speed in micro-lubrication machining
The cutting tool cuts the metal by breaking the metal layer. The fracture of the metal layer means that the external force destroys the metal structure while releasing the internal energy of the metal in the form of heat. During cutting, on the one hand, the chip transfers the heat of the crack point to the surface of the cutting tool, and on the other hand, the chip is subject to bending stress and comes into contact with the cutting tool to produce frictional heat due to the relatively rapid movement. The temperature rises rapidly. During the cutting process, the high-heat solid metal meets the rapid cooling effect of the cutting fluid, which will cause rapid quenching and produce a quenching effect, which will destroy the crystal phase structure. At the same time, the molecular misalignment in the crystal phase increases, making the metal hard and brittle. . When the cutting tool finishes cutting away from the workpiece, the hot tip will contact the coolant to produce a "quenching reaction", which makes the cutting tool hard and brittle, especially coated cutting tools, which affects the life of the cutting tool. Because the intensity of the quenching effect is proportional to the temperature difference, increasing the cutting speed will make the cutting tool higher temperature, and the strong quenching reaction caused by the larger temperature difference will further reduce the life of the cutting tool. This is why the higher the cutting speed, the shorter the life of the cutting tool.
During micro-lubrication processing, the lubricant is sprayed to the processing surface in the form of mist particles, which will not produce rapid cooling effect and no quenching effect.Moreover, as the cutting speed is increased, the cutting fracture point of the workpiece will appear in advance and the heat source of the crack point will be far away from the tool tip. Because the heat is concentrated on the workpiece and the chip, the heat source of the cutting tool is only a small part of the heat conduction and friction with the chip contact point. Increasing the cutting speed will make the chip more curved and leave the workpiece and the cutting tool at a faster speed, effectively reducing The time that the chip conducts thermal energy. The high temperature remaining on the workpiece can soften the surface of the workpiece, making cutting tools easier to cut. Therefore, in general, micro-lubrication is suitable for increasing cutting speed.