A modified infrared emissivity model accurately determining dynamic temperatures for belt grinding Inconel 718

Abstract

The temperature of belt grinding significantly influences the quality of Inconel 718 workpieces that are widely used in the aerospace and energy fields. The single-color infrared radiation (IR) camera is frequently used to measure grinding temperatures, where material-surface emissivity is a key parameter. However, accurately calculating surface emissivity in a simple and fast way is still a challenge at present. In this study, a modified fourth-power-law model (MFM), which considers the effects of radiation waveband and background radiation, and takes the ambient temperature, the temperature under emissivity of 1 and the reference temperature as inputs, is proposed to calculate the dynamic surface emissivity in a simple and fast way. The MFM clarifies the physical relationship among the input temperatures, surface emissivity and grinding temperatures. The results of dry, constant-force belt grinding Inconel 718 that was processed by forging and isothermally annealing show that the MFM-determined dynamic surface emissivity and grinding temperatures have relative errors of below 0.5 % and 2.1 %, respectively, which are one or even two orders of magnitude lower than those produced by previous methods. The relevant finite element analysis (FEA) model confirms the elliptical temperature distribution with the largest temperature change rate along the grinding direction on the grinding surface. The established MFM provides a simple and fast way to accurately calculate the dynamic surface emissivity and temperatures for belt grinding Inconel 718, and could be applied in other machining practices.