Analysis of Grinding Burn Mechanism of Titanium Rod
There is serious grinding wheel adhesion during the grinding process of titanium rods, and the grinding force and grinding temperature are very high, so grinding burns and cracks simply occur. When grinding titanium rods with ordinary abrasives, even if the grinding depth is small, grinding burns and cracks will occur on the ground surface. Approximately yellow-brown spots, hairline-like cracks, the direction is straight with the grinding direction, with a large amount of grinding, there will be scale-like wrinkles and plastic deformation of the metal deposit on the surface. What kind of substance is this? Let's take a look at the chemical reaction formula of silicon carbide abrasive grain grinding titanium rod: SiC+Ti→TiC+Si. , And look at the oxidation reaction formula of silicon carbide abrasive grains at a certain atmospheric temperature: SiC+2O2→SiO2+CO2.
Titanium rods have been widely used in the aerospace industry at home and abroad for their outstanding heat and corrosion resistance and particularly high specific strength. To align the grinding burn problem that occurs easily in the grinding process of titanium rods, use leading testing methods to measure the grinding force, grinding temperature, workpiece surface roughness and surface trace, and surface layer metallography during the grinding process. The arrangement and microhardness change rules were analyzed and discussed. The research results show that TC6 titanium rod burns when the grinding temperature exceeds 600℃. Surface tracing gradually deteriorates with the increase of grinding temperature. When severe burns occur, cracks occur on the surface of the workpiece, and the direction is roughly straight with the grinding direction. When the workpiece is burned, the metallographic arrangement of the surface layer of the material changes, and the α-phase particles are significantly larger, which reduces the physical and mechanical properties of the titanium rod. The research results provide theoretical and experimental basis for seeking optimized high-efficiency and high-precision titanium rod grinding processing technology.
In the meantime, a part of the carbon atoms will be scattered to the surface of the workpiece to be ground. Under the effect of the sliding shear force, the SiO2 oxide film will be peeled off, forming SiC abrasive particles oxidized wear, while the surface of the workpiece will leave a loose layer of oxygen and carbon elements, which is counterproductive Loss of the carbon weakened layer occurs on the surface of the abrasive particles, the hardness of the SiC abrasive particles decreases, the grinding force increases, the wear of the grinding wheel increases, and the increase in the grinding temperature is inevitable. From the microscopic level, the process of the formation of abrasive particles and adhesion is that the cutting edge first appears small area adhesion and gradually large area adhesion, the abrasive particles are finely broken, and then the abrasive particles are broken and fall, plastic deformation occurs in the grinding area of the titanium rod. The abrasive particles and the workpiece are bonded to each other, which has both physical adsorption and chemical adsorption effects. With the relative sliding shear force, the processed material is transferred to the abrasive particles. This is the entire process of the grinding wheel adhesion.
The adhesion of the grinding wheel simply constitutes a blockage, which increases the temperature of the grinding area, and the grinding surface produces distributed grinding burns along the workpiece layer, accompanied by a degeneration layer and residual stress. In the grinding cooling process, when the grinding depth is large, the density of the oxide film on the grinding surface reaches the critical temperature, and the temperature of the grinding arc zone will rise sharply due to the film formation of the grinding fluid. The cooling effect Getting worse. When the elevated temperature exceeds the limit that the usual abrasive can withstand, the abrasive particles will fall due to softening damage. Therefore, it is necessary to select a new type of super hard grinding wheel to further increase the high temperature tolerance of the grinding arc zone.