An internal cooling grinding wheel: From design to application

Abstract

The cooling and lubrication conditions during the grinding process significantly impact the nickel-based superalloy's final service performance. The existing jet cooling and heat pipe technology can solve the heat conduction problem in the grinding process of superalloy. Still, managing cooling, lubrication, and chip removal are difficult. This paper describes the design and fabrication of a novel central fluid-through internal cooling slotted grinding wheel with an ordered grain pattern to improve the grinding machinability of a nickel-based superalloy. The pressurized grinding fluid was ejected into the grinding zone via the pipe and tool holder from the lower-end face of the inner cooling wheel. The structure of the grinding wheel was optimized using computational fluid dynamics (CFD). The flow field in the grinding area achieved the highest overall flow rate, distribution homogeneity, and effective exit flow when the internal flow channel had four through-holes. The exit for the inner runner is located at the abrasive edge and diamond staggered pattern. Single-layer brazing was used to create cubic boron nitride (CBN) abrasive rings with various abrasive patterns. The internal cooling wheel matrix and various components were prepared according to the optimized grinding wheel geometry model. A grinding test bench was built to conduct an experimental study of grinding the nickel-based alloy GH4169. The results show that, under the same conditions, a diamond-shaped staggered pattern obtains lower grinding temperature, lower surface roughness, better surface morphology, and more significant residual compressive stress distribution than an abrasive cluster diagonal circular staggered pattern or disordered pattern. The average effective flow rate calculated by CFD is increased by 42.3% when compared to the disordered pattern. In the experiment, compared to the disordered arrangement, with the increase of grinding wheel’s rotating speed and coolant pressure, the average grinding temperature of abrasive grain with diamond-interleaved arrangement decreases by 58.2% and 51.7% respectively, and its surface hardening degree decreases by 11.1% and 11.7% respectively.