Analysis of the influence of noise caused by the limit speed of imported bearings

Rolling sound of the bearing and its control method The rolling sound is a kind of slippery continuous sound that the rolling element rolls on the rolling surface when the imported bearing is running, which is the unique basic sound that all rolling bearings will produce. The general bearing sound is the rolling sound plus other sounds. The ball bearing's raceway sound is irregular, the frequency is above 1000Hz, its main frequency does not change with the speed, but its total sound pressure level increases with the increase of the speed. For bearings with large rolling sounds, the sound pressure level of the raceway sound decreases with the increase of viscosity; while for bearings with small raceway sound, the sound pressure level decreases when the viscosity increases to about 20 mm2/s or more. For the increase. The greater the rigidity of the bearing housing, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and main frequency of the raceway sound will increase sharply as the radial clearance decreases. The method of controlling the rolling sound is to select a low-noise bearing, that is, a bearing with a small waviness, and carefully select the conditions of use. The raceway sound often affects the noise of the entire machine, and reducing the raceway sound can reduce the noise of the entire machine.

Impact sound of rolling element and its control method When a larger type of ball bearing or cylindrical roller bearing runs at low speed under pure radial load, the rolling element in the non-loading zone will impact the cage due to the small centrifugal force of the rolling element. Or the raceway makes noise. But as the speed increases, the sound will disappear. The control methods for the impact sound of the rolling element are: appropriately reducing the radial clearance, and using a bearing having a reasonable structure and a flexible material.

Rolling sound of imported bearings and its control method Rolling sound is a harsh metal friction sound that can occur in cylindrical roller bearings in all occasions. Most of them occur in grease-lubricated larger types of bearings, and the performance of base oil deteriorates. It is more likely to occur in grease and hardly occurs when oil is lubricated. In addition, it is more likely to occur in winter. When subjected to pure radial load, it is easy to occur in the case of large radial clearance, and it is easy to occur in a certain speed range depending on the size of the model, and it will occur continuously. It will appear intermittently. Foreign raceway take special processing methods to prevent sound jarring, use this bearing, if necessary or appropriate to reduce the radial bearing clearance, excellent performance and improve the grease to match the mechanical rigidity of the bearing .

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Nsk bearing common troubleshooting method

Due to the inaccurate measurement of the shaft diameter and the bearing housing hole or the roughness of the mating surface does not meet the standard requirements, an excessive interference fit is caused, so that the nsk bearing race is greatly squeezed, resulting in a decrease in the radial clearance of the bearing itself. It makes the bearing difficult to rotate, generates heat, and the wear is intensified or stuck. In severe cases, the inner and outer races of the bearing will be cracked during installation. The non-rotating seat often adopts a gap or a small interference, so that the rotation of the seat may cause a slight creep, and the contact surface of the race with the rolling element is continuously replaced, and the raceway of the race is evenly worn. At the same time, it is also possible to eliminate the axial jam of the rolling elements in the bearing due to the thermal elongation of the shaft. However, if the gap is too large, the non-rotating seat will rotate together with the rolling elements, causing severe wear of the shaft (or the bearing housing hole) and the inner race (or the outer race), and the friction causes the bearing to heat and vibrate.

B. Improper assembly method

When the interference of the nsk bearing and the shaft diameter or the bearing housing hole is small, the press-in method is often used for assembly. The easiest way is to use a copper rod and a hand hammer to symmetrically tap the bearing with an interference fit in a certain order to make the bearing smoothly pressed in. In addition, it is also possible to use a sleeve made of soft metal to be hammered in or pressed by a press. If improperly operated, the seat will be deformed and cracked, or the hammer will be hit on the non-interference fit seat, which will cause the raceway and the rolling element to be indented or the bearing to be indirectly damaged.

C. Improper temperature control during assembly

When the nsk bearing is assembled, if it has a large interference with the shaft diameter, it is usually assembled by hot charging. The bearing is placed in the oil drum filled with organic oil. The outside of the oil drum is heated by hot water or flame. The temperature of the oil required for the process is controlled at 80 ° C ~ 90 ° C, generally not more than 100 ° C, and the maximum is not more than 120 ° C. After the bearing is heated, it is quickly taken out and placed on the journal. If the temperature is not properly controlled, the heating temperature will be too high, which will cause the bearing to temper and the hardness will decrease. The bearing will be prone to wear, peeling and even cracking during operation.

D. Improper gap adjustment during assembly

The gap of the rolling bearing is divided into a radial gap and an axial gap, and its function is to ensure the normal operation and lubrication of the rolling elements and to compensate for the thermal elongation.

For bearings with adjustable clearance, because of the proportional relationship between the axial clearance and the radial clearance, the installation is to adjust the axial clearance to obtain the required radial clearance, and they are generally Used in pairs (ie at both ends or at one end of the shaft), therefore, it is only necessary to adjust the axial clearance of one bearing. Generally, the gasket is used to adjust the axial clearance, and some can also be adjusted by screws or thrust rings.

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