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The reliability and service life of angular contact bal […]
The reliability and service life of angular contact ball bearings have a certain dispersion even under good working conditions. For important equipment, especially angular contact bearings that work under harsh conditions, whether the angular contact bearings installed in them work reliably and how long they can continue to run naturally becomes a special concern for the application department. At the same time, it is often directly related to obvious economic benefits or serious accident losses. Therefore, diagnostic technology has naturally become a technical development field that the application department pays great attention to.
High magnification scanning electron microscope observed the fractured part of the angular contact ball bearing, and found the following symptoms:
1. Zoom in to observe the angular contact ball bearing, and many fan-shaped patterns can be seen in the micro area.
2. There are fatigue arcs and a large number of corrosion pits before the crack.
3. The shape of the fan-shaped pattern is different from different angles, and the fan-shaped pattern is formed by connecting cracks on different planes. A typical fatigue crack was found by observing the crack propagation area with high magnification. By scanning the crack source at low magnification, it can be found that there are beach lines around the crack source, a large number of corrosion pits are distributed in the crack source area, and some of the corrosion pits are connected into a line, showing the shape of mud lines.
4. The acceptance stress is high, and the water jacket is in contact with the thermal rib of the cylinder liner. The pressure at point b is very small. The bearing water jacket mainly bears three kinds of stress: explosion stress, assembly stress and thermal stress. The maximum stress of the water jacket is the circumferential stress, and its value is about 128MPa. Oily angular contact ball ignition is a random anomaly. Abnormal defects such as fire burns of the workpiece often seriously affect the appearance quality and product performance of the workpiece, and even cause the workpiece to be unqualified and scrapped, especially for precision workpieces or important workpiece surfaces that require high appearance quality.
5. When induction heating is observed in the production of angular contact bearings, the ignition between the angular contact bearing and the inductor is often not a point contact, and the noise generated by the angular contact ball bearing is very sensitive. Therefore, in order to maintain the smooth operation of angular contact bearings, sintered bronze oil-impregnated bearings with high reliability are generally used, and some measures should be taken, such as appropriate control of sintering conditions to make the alloy structure into a single phase, and anti-corrosion process measures can be taken; another The method is to generate compressive stress on the outer surface of the workpiece to offset the tensile stress of the water jacket in use.