During the grinding process of the bearing ring, due to the cutting, scoring and frictional effects of the abrasive grains on the workpiece, the metal surface is plastically deformed, and the relative displacement between the metal molecules inside the workpiece generates internal friction and heat; when the grinding wheel is cutting, relative to the workpiece The speed is very high, causing severe external friction with the workpiece surface to generate heat. And because the cutting of each abrasive is instantaneous, the heat is generated instantaneously and cannot be dissipated in time, so the instantaneous temperature in the grinding area is relatively high. High, generally reaching 800~1500℃. If the heat dissipation measures are not good, it is easy to cause burns on the surface of the workpiece, that is, secondary quenching and high-temperature tempering will occur on the surface of the workpiece (generally tens of microns to over microns), which will cause damage. The structure on the surface of the workpiece has been removed, and severe burns can be seen with the naked eye. A severe burnt yellow or black oxide film appears on the surface. Minor burns can only be observed after being etched with dilute acidic solution. The burned area will appear black. Burns can reduce the service life of the workpiece.