Eccentric bearing installation guide

1. The assembly site should be as clean as possible and free of dust;

2, to avoid eccentric bearings contaminated with dust, pollutants and moisture (contaminants have adverse effects on the operation and service life of rolling bearings);

3. Check the dimensional accuracy and cleanliness of the mating surface on the bearing housing bore and the shaft;

4. Apply a little oil or a little grease to the mating surface of the bearing ring;

5. Ensure that the shaft and housing bore have a 10°~15° guide chamfer;

6. Do not overcool the eccentric bearing (the moisture generated by condensation can cause corrosion of the bearing surface of the bearing and the bearing);

7. After installation, fill the bearing with lubricant and check that the bearing configuration is working properly.

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Shaft bearing selection

The accuracy of the bearing used on the machine tool spindle should be ISOP5 or above (P5 or P4 is the ISO accuracy level, usually from low to high (P0, P6, P5, P4, P2), and for high speed CNC machine tools, machining centers, etc. For high-precision machine tool spindle bearings, ISOP4 or higher accuracy is required. Spindle bearings include angular contact ball bearings, tapered roller bearings, and cylindrical roller bearings.

1, precision angular contact ball bearings

Precision angular contact ball bearings are widely used. The rolling element of an angular contact ball bearing is a ball because it is a point contact (distinguished from the line contact of the roller bearing), so it can provide higher rotation speed and smaller heat generation. And higher rotation accuracy. In some ultra-high-speed spindle applications, hybrid bearings with ceramic balls (usually si3N4 or Al203) are also used. The metal processing reporter believes that compared with the traditional fully hardened steel ball, the ceramic ball material itself gives the ceramic ball bearing the characteristics of high rigidity, high rotation speed, high temperature resistance and long service life, so as to meet the high-end customer's bearing product products. demand.

2, precision cylindrical roller bearings

In machine tool spindle applications, double row precision cylindrical roller bearings are also used, usually in combination with precision angular contact ball bearings or thrust bearings. These bearings can withstand large radial loads and allow for higher rotational speeds. The two rows of rollers in the metal machining in-line bearing are arranged in a crosswise manner. The fluctuation frequency during rotation is greatly improved compared with the single row bearing, and the amplitude is reduced by 60%-70%. These bearings usually come in two forms: NN30, NN30K two series bearing inner ring with ribs, outer ring can be separated; NNU49, NNU49K two series bearing outer ring with ribs, inner ring can be separated, of which NN30K and NNU49K series The inner ring is a tapered hole (taper 1:12), which cooperates with the tapered journal of the main shaft, and moves the inner ring axially to make the inner ring expand, so that the bearing clearance can be reduced or even pre-tensioned (negative clearance) status). Cylindrical bore bearings are usually hot-fitted, with an interference fit to reduce bearing clearance or to pre-tension the bearing. For the NNU49 series bearings that can be separated from the inner ring, the main shaft is usually mounted on the main shaft and then the raceway is finished to improve the spindle rotation accuracy.

3, precision tapered roller bearings

In some machine applications with heavy loads and speed requirements, such as roughing of forgings, wire machines for oil pipelines, heavy duty lathes and milling machines, the selection of precision tapered roller bearings is an ideal solution. Because the roller of the tapered roller bearing is designed for line contact, it can provide high rigidity and load to the main shaft. In addition, the tapered roller bearing is a pure rolling bearing design, which can reduce the bearing operation. Torque and heat to ensure spindle speed and accuracy. Since the tapered roller bearing can adjust the axial preload (play) during installation, this allows the customer to better optimize the bearing clearance adjustment throughout the life of the bearing.
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