Calculation of snails

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2. The pre tightening force must be calculated, and the internal structure and relevant dimensions of the bearing, including groove curvature, steel ball curvature, material properties, etc., must be considered in the calculation. After the calculation, it is converted into the torque of the bolt, because the general preload is applied through the bolt, so the preload can be applied through the torque wrench. It should be noted that many domestic occasions rely on experience to control the preload. This method is e to the poor consistency of bearing accuracy in China, and the non-standard control method of preload. Tapered roller bearings are pure rolling regardless of the positive and negative clearance, and the biggest heating source is the sliding friction between the large end face of the roller and the large rib of the inner ring, while self-aligning roller bearings have sliding friction with the inner and outer ring raceways regardless of the positive and negative clearance. In general, the reason for the sharp increase of calorific value in the negative clearance is that the preload destroys the lubricating oil film and makes the two metal contact surfaces adhere directly. However, it is not the case for diagonal contact ball bearings. Whether the bearings are pure rolling after assembly depends on the assembly state of the bearings. If the inner sleeve of tapered roller bearing does not have enough compression in the opposite direction, it is not pure rolling state
bearing preloading is generally used under high precision operation conditions. Theoretically speaking, the bearing runs most smoothly under zero clearance or even negative clearance condition to a certain extent. At this time, the stiffness of the bearing is given the most effective play, and the noise of the bearing is the lowest. Therefore, the bearing should work under this condition as far as possible. However, considering the factors such as the installation fit of the bearing and the material deformation caused by the temperature change ring working, the bearing is reserved with positive clearance ring processing. In order to be used in the working conditions of high-precision operation, after the bearing and related parts are installed and matched, some measures are taken to apply the preload. By adjusting the position of the inner and outer rings, the bearing clearance is adjusted, so that the bearing clearance value is zero or negative, which can ensure the smooth operation of the bearing under high-precision operation
the bearing models to be preloaded basically cover all conventional models. In other words, all types of bearings used in high precision field need to be preloaded. Including: deep groove ball bearing (used in household appliances), angular contact ball bearing (it must be preloaded when used on the spindle of high-speed machine tool), thrust bearing, tapered roller bearing, cylindrical roller bearing, etc., preloading can be seen. It should be noted that: there is a degree of preloading, too much preloading will also cause the bearing working temperature rise too high, which is easy to cause the early failure of the bearing. But the preload is too small, and the bearing can not run smoothly at high speed. Therefore, a variable preload adjusting mechanism has been developed
pre tightening can be divided into mild pre tightening, moderate pre tightening and severe pre tightening. When the bearing needs high-speed operation and stable operation, it should be slightly preloaded; When the bearing needs to improve the bearing capacity and stiffness, and the speed is not high, moderate or severe preloading should be implemented. Slight preloading is only to rece the movement between the rolling element and raceway in the non-contact area e to the clearance when the bearing is working. Therefore, it is enough to ensure that the bearing clearance is zero or above zero; Moderate or severe clearance is below zero negative clearance.

3. Right hand spiral rule, thumb direction is m direction. It is positive.