Grinding heat of SKF imported bearings

Source: China Bearing Network Time: 2013-04-25

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In the grinding process of SKF imported bearings; grinding wheel and workpiece touch area; cost a lot of energy; a lot of grinding heat occurs; part of the instantaneous high temperature of the grinding zone is formed. The linear heat transfer heat transfer theoretical formula is used to derive and calculate Or use the infrared method and the thermocouple method to measure the instantaneous temperature under the test conditions; the instantaneous temperature in the grinding zone can be as high as 1000-1500 Â° C in the range of 0.1 to 0. 001 ms. Such instantaneous high temperature; High-temperature oxidation of the outer surface of the inevitable depth; amorphous arrangement, high temperature tempering, secondary quenching; and even burn cracking and other changes.
(1) The effect of oxygen on the surface of the steel and the air in the transient high temperature effect of the SKF imported bearing; the thin layer of iron oxide which is extremely thin (20-30 nm). It is worth noting the thickness of the oxide layer and the appearance of the surface. The test results of the total thickness of the enthalpy layer are in a corresponding relationship. This indicates that the thickness of the oxide layer is directly related to the grinding process; it is an important marker of the quality of grinding.
(2) SKF imported bearings amorphous state The instantaneous high temperature of the grinding zone causes the workpiece to reach the molten state; the molten metal molecular flow is uniformly applied to the work surface; and is cooled by the base metal at a very fast speed. Formed a very thin layer of amorphous arrangement. It has high hardness and resistance; but it only needs about 10nm; it is very simple to be removed in the fine grinding process.
(3) The instantaneous high temperature of the high-temperature tempering layer grinding zone of SKF imported bearings can be heated to a temperature higher than the tempering heating temperature of the workpiece at a certain depth (10-100 nm). Without reaching the austenitizing temperature Followed by the progress of the heating temperature; the appearance of the layer will occur with the reheating or high temperature tempering corresponding to the heating temperature; the hardness will also decrease. The higher the heating temperature; the harder the hardness reduction.
(4) Two-layer quenching layer of SKF imported bearing When the instantaneous high temperature of the grinding zone heats the outer surface of the workpiece to above the austenitizing temperature (Ac1); the austenitizing of the layer is arranged in the subsequent cooling process; It has been quenched from the head into a martensite arrangement. However, any workpiece with secondary quenching burns must be a high-temperature tempering layer with extremely low hardness under the secondary quenching layer.
(5) SKF imported bearing grinding cracks secondary quenching burns will change the stress of the outer surface of the workpiece. The secondary quenching zone is under pressure; the high temperature tempering zone underneath has the largest tensile stress; here is the most likely The local crack that occurs at the center of the crack is most simply conveyed along the original austenite grain boundary. Severe burns will cause the entire surface of the grinding to show cracks (more cracks) to form the workpiece.

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