Installation of plastic bearings
a. When the bearing is installed, it is necessary to apply equal pressure around the circle on the end surface of the ferrule. One side (such as the outer ring) applies pressure, and the other side (such as the inner ring) of the ferrule is pushed in by the rolling body. This often causes indentations or abrasions on the rolling body surface. Note that this method must not be used In particular, non-separable bearings are installed on the shaft and the bearing housing at the same time.
b. When installing the bearing, the temperature range of the plastic material used for the plastic bearing must be considered. If the temperature is too high, the bearing will be damaged in a short time.
Fitting of plastic bearings
a: Interference
The inner ring and the outer ring of the rolling element are fixed on the shaft or the bearing box. When the bearing is subjected to a load, the relative movement of the ring and the shaft or the bearing box in the radial, axial and rotational directions does not occur. The movement will cause friction, friction corrosion or friction cracks on the mating surface, which will cause damage to the bearings, shafts and bearing housings, and then the abrasion powder will be mixed into the bearings, which will cause poor operation, abnormal heating or vibration.
As for the method of fixing the bearing, it is better to leave an interference amount on the mating surface of the ferrule and the shaft or the bearing box, and it is better to perform a static fit. This fit can evenly distribute the load of the thin-walled ferrule on the circumference. Does not affect the load capacity of the bearing.
However, when the static fit is used, in addition to the inconvenience of installing and removing the bearing, if the bearing uses a separate bearing, it cannot move axially, so it cannot be used in all occasions.
b: Choice of fit
b- cooperative selection principle
1. According to the direction and nature of the load acting on the bearing and the rotation direction of the inner and outer rings, the load on each ring can be divided into rotating load, static load, or non-directional load, and the ring bearing the rotating load and non-directional load Should adopt static fit (interference fit), the ring bearing static load, transition fit or dynamic fit (clearance fit), bearing load or vibration or impact load, the interference must increase, use hollow For shafts, thin-walled bearing housings or light alloy or plastic bearing housings, the interference must also be increased.
2. When high rotation accuracy is required, high-precision bearings must be used, and the dimensional accuracy of the shaft and the bearing box must be improved to avoid excessive interference. If the interference is excessive, the geometric accuracy of the bearing or the shaft box can be improved. Affects the geometry of the bearing ring, thereby impairing the rotation accuracy of the bearing. If non-separable bearings (such as deep groove ball bearings) use a static fit on the inner and outer rings, the installation and disassembly of the bearing is inconvenient. An effective method is to use one side of the outer ring. Moving together.
Recommended fit
Regarding the shaft diameter and hole size tolerance of the shaft and bearing box installed with plastic bearings, in the metric series, ISO283 (dimension tolerance and fit) has corresponding standards. Therefore, the fit tolerance has been determined by the selected shaft diameter and hole size tolerance.
