A Study on a High-Speed NC Gear Grinding Machine Using a Screw-Shaped CBN Wheel

This paper describes a basic study for designing a high-speed NC gear grinding machine using a screw-shaped CBN wheel. Gear grinding machines using screw-shaped grinding wheels are quite prevalent. However, their productivity is not high, because the rotary speed of their spindles is very low. Therefore, the authors raised the maximum rotary speeds of the grinding spindle and the workspindle to 12,000 rpm and 3,000 rpm, respectively, in order to use a high-speed multithread CBN wheel. A magnetic scale whose wave length is long but pitch accuracy is high enough was used for detecting such a high-speed rotation. Since the wave length of the scale is long, a high-resolution interpolation using two-phase type PLL proposed by Emura was used. Both spindles are direct-drive type for removing backlash. When we grind gears, the initial setting between rotary angles of grinding wheel and work is required. The authors tried to automatically set the initial rotary angles by using a CCD camera.