KOYO bearing inspection and judgment, cleaning, replacement

Cleaning of KOYO bearings: When disassembling KOYO bearings, first record the appearance of KOYO bearings, confirm the residual amount of lubricants, and then wash the KOYO bearings after sampling the lubricants for inspection. As a cleaning agent, gasoline and kerosene are commonly used. The cleaning of the removed KOYO bearings is divided into coarse cleaning and fine cleaning. They are placed in the container respectively, and the metal mesh bottom is placed first so that the KOYO bearing does not directly contact the container. In the case of rough cleaning, if the KOYO bearing is rotated with dirt, it will damage the rolling surface of the KOYO bearing and should be noted. In the rough cleaning oil, use a brush to remove the grease and the adhesive. After it is almost clean, it is transferred to the fine wash. Fine washing is to carefully clean the KOYO bearing while rotating in the cleaning oil. In addition, the cleaning oil should always be kept clean.

Inspection and judgment of KOYO bearings: In order to judge whether the removed KOYO bearings can be used, check them after cleaning the KOYO bearings. Check the condition of the raceway surface, the rolling surface, the mating surface, the wear of the cage, the increase of the KOYO bearing clearance, and the damage and abnormality that are irrelevant in dimensional accuracy. For non-separable small ball KOYO bearings, use one hand to support the inner ring horizontally and rotate the outer ring to check if it is smooth.

Separate KOYO bearings such as tapered roller bearings can be inspected separately for the rolling surfaces of the rolling elements and the outer ring. 2 Large KOYO bearings can not be rotated by hand. Pay attention to the appearance of rolling elements, raceway surfaces, cages, ribs, etc. The higher the importance of KOYO bearings, the more careful inspection is required.

The judgment of KOYO bearing reusable (KOYO bearing replacement) is determined by considering KOYO bearing damage degree, mechanical performance, importance, operating conditions, and the period of next inspection. However, if you have the following defects, you can no longer use them. You must replace the new KOYO bearings:

(a) cracks or notches on any of the inner ring, the outer ring, the rolling elements, and the cage;

(b) rupture on any of the ferrules and rolling elements;

(c) Significant jams on the raceway surface, ribs and rolling elements;

(d) the cage is worn significantly or the rivet is significantly slack;

(e) There is rust and injury on the raceway surface and the rolling elements;

(f) There are severe indentations and marks on the raceway surface and rolling elements;

(g) The inner diameter of the inner ring or the outer diameter of the outer ring has obvious creep;

(h) discoloration due to heat;

(i) KOYO bearings sealed with grease, and the seal or dust cover is damaged.

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NTN bearing installation method

Due to the structure, fit and conditions of the NTN bearing, in general, since the shaft is mostly rotated, the inner ring needs an interference fit. Cylindrical hole NTN bearings, press with a press, or use a hot charging method. For taper holes, mount directly on the taper shaft or with a sleeve.

When installed in the outer casing, the general clearance fits a lot, and the outer ring has an interference amount, which is usually pressed by a press or a cold shrink fit method after cooling. With dry ice as the coolant and cold shrink fit, the moisture in the air will condense on the surface of the NTN bearing. Therefore, appropriate rust prevention measures are required.

1. Installation of cylindrical bore NTN bearing

(1) Method of pressing with a press

Small NTN bearings are widely used by presses. The pad is placed in the inner ring and pressed quietly to the inner ring with a press to closely contact the shaft shoulder. Installing the inner ring on the outer ring pad is the cause of the indentation and crushing on the raceway, so it is absolutely prohibited.

When operating, it is best to apply oil to the mating surface beforehand. If you have to use a hammer to knock on the installation, you should put a block on the inner ring. This practice has often become the cause of NTN bearing operation, so it is limited to the case of small interference, can not be used for large interference, or medium and large NTN bearings.

For example, non-separable NTN bearings such as deep groove ball NTN bearings, where the inner ring and the outer ring need to be installed with interference, use the pad pad and press the inner ring and the outer ring simultaneously with a screw or oil pressure. The outer ring of the self-aligning ball NTN bearing is easy to tilt, and even if it is not an interference fit, it is better to install the pad.

For example, a split-type NTN bearing such as a cylindrical roller NTN bearing or a tapered roller NTN bearing can be mounted on the shaft and the outer ring respectively, and the inner ring and the outer ring respectively combined are combined. It is to steadily close the two so that the center of the two does not deviate, and the press-in will cause the raceway surface to be damaged.

(2) Method of hot charging

Large NTN bearings require a lot of force when pressed in, so it is difficult to press in. Therefore, the method of heating the NTN bearing in oil to expand it and then attaching it to the shaft is widely used. With this method, it is possible to complete the work in a short time without adding undue force to the NTN bearing.

The heating temperature of the NTN bearing is based on the NTN bearing size and the required interference. The precautions for hot loading operations are as follows:

(a) Do not heat the NTN bearing to above 120 °C;

(b) In order to prevent the NTN bearing from directly contacting the bottom of the oil tank, it is best to consider placing the NTN bearing on the metal net or lifting the NTN bearing;

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