STUDY ON ULTRA-HIGH SPEED CUT-OFF GRINDING

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Grinding efficiency is in proportion to peripheral speed of grinding wheel. Therefore, if the peripheral speed is increased, grinding efficiency will be improved. An ultra-high-speed grinding machine wa developed whose peripheral speed is over 400m/s. The peripheral speed is limited below 300 m/s in the grinding experiment, because of a low failure strength of the rotating wheel. In this project, cBN wheels (blades) for cut-off grinding were developed whose maximum peripheral speed is 400 m/s.(1) Structural analysis of flange and bladeTo realize the actual production utilized the ultra-high speed grinding, the blade with the center hole was fixed with a flange system. An analytical model for cut-off grinding was created to consider both the effect of the center hole and friction between the flange and the blade. As a result, it is found that the peripheral speed of 400 m/s can be realized, when the friction force between the flange and the blade is increased, and material such as titan … More ium alloy or CFRP is used for the flange and blade, whose specific young's modulus is high.(2) Ultra-high speed rotational test of blade for cut-off grindingBased on the analytical result, flange and blade were manufactured and rotational failure tests in ultra-high speed domain (20,000〜35,000 rpm (459 m/s)) were carried out using a spin tester. After rotational test of the carbon steel blade only at 30,000 rpm, plastic deformation remained on the blade along the circumferential direction. In the case of the blade that is fixed with flange with low pressure, plastic deformation was recognized around the holes for fixing bolts after rotational test. However, plastic deformation was not recognized in large fixing pressure.(3) Ultra-high speed cut-off grinding experimentBased on the results of the spin tests, flange made by titanium alloy and the metal bonded grinding wheel with titanium core was used for ultra-high speed cut-off grinding. Grinding tests with peripheral-speed of 400 m/s were successfully carried out. Less