FAG bearings, grinding heat changes

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FAG bearings, grinding heat changes
FAG Bearings grinding wheel and workpiece contact area, consume a lot of energy, and produce large amounts of grinding heat, causing local tr ansient high temperature of the grinding zone. Use of linear movement heat source heat transfer theory formula derivation, the instantaneous temperature in the method of calculation or application of infrared and thermocouple method measured experimental conditions, can be found in the 0.1 ~ 0.001ms, the instantaneous temperature of the grinding zone can be as high as 1000 to 1500 ℃. This instantaneous high temperature, sufficient to enable the work surface to a certain depth of surface layer of high temperature oxidation, amorphous organization, high-temperature tempering and secondary quenching, and even burn a variety of changes such as cracking.
(1) the surface oxide layer
Instantaneous under high temperature steel surface and the role of oxygen in the air or into a thin (20 ~ 30nm) thin layer of iron oxide. It is noteworthy that the oxide thickness and surface grinding of the metamorphic layer total thickness of the test results showed a corresponding relati onship. This shows that the oxide thickness and FAG bearings grinding process is directly related to an important symbol of the grinding quality.ball bearing companies

(2) amorphous tissue layer
FAG bearings grinding instantaneous heat the surface of the molten state, the molten metal molecular flow is evenly coated on the surface of the work, and the base metal to be cooled extremely rapidly, forming a very thin layer of non- crystalline tissue layers. It has high hardness and toughness, but it is only about 10nm, it is easy to be removed in precision grinding.machine bearing

(3) layer of high temperature tempering
FAG bearings grinding instantaneous heat can make the surface a certain depth (10 to 100nm) is heated to a temperature higher than that of the workpiece tempering heating. With the improvement o f the heating temperature in the case did not reach the austenitizing temperature, the surface layer will result in organizational changes that corresponds with the heating temperature to return fire or high temperature tempering, the hardness decreases. The higher the heating temperature, the decrease in hardness is also more powerful.high speed bearing

(4) the second floor of hardened layer
FAG bearings grinding the instantaneous high temperature of the surface layer is heated to above the austenitizing temperature (Ac1), the austenitizing organization of the layer in the subsequent cooling process, but also be re-quenched martensite organization. Where there are secondary quenching the workpiece burn, the secondary hardening layer under high temperature tempering layer must be very low hardness.

(5) grinding cracks
Secondary quenching burn will make the surface layer of st ress changes. Secondary quenching zone in compression, the following high-temperature tempering zone material existence of the maximum tensile stress, here is the most likely to crack the core. Crack is most likely to spread along the original austenite grain boundaries. Serious burns to the grinding surface cracks (mostly cracks) caused by the workpiece scrapped