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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