News_News_Liaocheng Kunmei Bearing Co., Ltd.

07/12/2024

Identification of good and bad motor bearings

Maintenance and judgment of bearing In order to judge whether the disassembled bearing can be used, it should be checked after the bearing is cleaned. Check the state of raceway surface, rolling surface and mating surface, the wear of cage, the increase of bearing clearance and the damage of irrelevant dimensional accuracy, which are abnormal. For non separable small ball bearings, support the inner ring horizontally with one hand and rotate the outer ring to confirm whether it is smooth. (1) Tapered roller bearings and other separate bearings can inspect the raceway surfaces of rolling elements and outer rings respectively. (2) Since large bearings cannot be rotated by hand, pay attention to the appearance of rolling elements, raceway surfaces, cages, edge retaining surfaces, etc. the higher the importance of bearings, the more careful the inspection is. Judgment of whether the bearing can be reused (bearing replacement) It is determined by considering the degree of bearing damage, mechanical performance, importance, operating conditions and the period until the next maintenance. However, if there are the following defects, they can no longer be used and must be replaced with new bearings. (1) There are cracks or notches on any one of the inner ring, outer ring, rolling element and cage (2) Any one of the ferrule and rolling element is broken (3) There is significant jamming on the raceway surface, retaining edge and rolling element (4) Significant wear of cage or significant relaxation of rivets (5) There is rust and damage on the raceway surface and rolling element (6) There are serious indentations and scratches on the raceway surface and rolling element (7) There is obvious creep on the inner diameter surface of the inner ring or the outer diameter surface of the outer ring (8) Discoloration caused by heat is obvious (9) The bearing, sealing ring or dust cover sealed with grease is obviously damaged Strengthening the maintenance and identification knowledge can not only effectively reduce the equipment failure rate, reduce the maintenance cost and the number of spare parts, but also greatly reduce the downtime and improve the economic benefits of enterprises, which is of great significance to further improve the equipment management!

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Identification of good and bad motor bearings

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06/19/2024

Causes of bearing waviness and its elimination

Reducing bearing noise is an urgent problem to be solved in improving bearing quality in bearing industry. The main factor affecting bearing noise is the waviness of bearing groove surface and steel ball surface. Waviness is caused by vibration in the grinding process. Therefore, it is very necessary to study the relationship between vibration and skin texture and the causes of vibration. Relationship between vibration and waviness There are many reasons affecting the waviness, which mainly depends on the vibration in the grinding process. The greater the vibration force, the greater the amplitude. With the increase of amplitude, the waviness value of waviness also increases, and the waviness value is directly proportional to the amplitude of vibrating body. In order to find out the cause of vibration, first measure the number of ripples, and then calculate which kind of vibrating body is. The relationship between them is: N vibration = an workpiece Where, n-number of revolutions per minute of vibrating body N workpiece - revolutions per minute of the workpiece A - number of corrugations of the workpiece on a circle Causes and elimination methods of vibration In the grinding process, the grinder mainly produces forced vibration, self-excited vibration and free vibration. Forced vibration accounts for more than 60%, self-excited vibration accounts for about 30%, and the rest are free vibration. 1. Forced vibration There are many reasons for forced vibration, but because the vibration frequency caused by forced vibration is often equal to or multiple equal to the frequency of the vibrating body itself, it is easy to find out the vibration source and eliminate it. 1. Caused by unbalanced grinding wheel (1) The grinding wheel shall be statically balanced once before rough repair, and then statically balanced once after rough repair, and then finish the grinding wheel. (2) When installing the grinding wheel, pay attention to make the flange of the grinding wheel perpendicular to the conical hole, so that the conical hole and the conical surface of the main shaft are in good contact. The two sides of the sand wheel shall be padded with paper of the same thickness to avoid the imbalance of the grinding wheel due to poor installation. (3) After the grinding is stopped and the coolant is turned off, the grinding wheel shall continue to idle for 5 ~ 7 minutes, and the special coolant on the grinding wheel shall be removed by centrifugal force. Otherwise, after the machine tool stops for a certain time, most of the coolant will solidify in the lower part of the grinding wheel. When the machine tool is restarted, the grinding wheel will be unbalanced. (4) Because the internal organization of the grinding wheel is uneven, even if the original balanced grinding wheel will produce new imbalance in the process of use, so it is best to adopt an automatic balancing device in the grinding process.

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Causes of bearing waviness and its elimination

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06/06/2024

Technical knowledge of spindle bearing

As a key component of the machine tool, the performance of the spindle will directly affect the rotation accuracy, speed, rigidity, temperature rise, noise and other parameters of the machine tool, and then affect the machining quality of the workpiece, such as the dimensional accuracy, surface roughness and other indicators of the parts. Therefore, in order to maintain excellent machine tool processing capacity, high-performance bearings must be used. The bearing accuracy used on the spindle of the machine tool shall be isop5 or above (P5 or P4 is the accuracy grade of ISO, usually P0, P6, P5, P4 and P2 from low to high). For the spindle support of high-speed and high-precision machine tools such as CNC machine tools and machining centers, the accuracy of isop4 or above shall be selected; Spindle bearings include angular contact ball bearings, tapered roller bearings, and cylindrical roller bearings. Precision angular contact ball bearing Among the above bearings, precision angular contact ball bearings are the most widely used. We all know that the rolling element of angular contact ball bearing is a ball; Because it is a kind of point contact (different from the line contact of roller bearing), it can provide higher speed, less heat and higher rotation accuracy. In some ultra-high speed spindle applications, hybrid bearings with ceramic balls (generally Si3N4 or Al2O3) will also be used. Compared with the traditional fully quenched steel ball, the characteristics of ceramic ball material endow ceramic ball bearing with the characteristics of high stiffness, high speed, high temperature resistance and long service life, so as to meet the needs of high-end customers for machine tool bearing products. As far as the contact angle of angular contact ball bearing is concerned, at present, the more popular contact angles are 15 ° and 25 °; Generally, the contact angle of 15 ° has relatively high speed performance, while the contact angle of 25 ° has high axial bearing capacity. Because the choice of preload has a great impact on the application of precision angular contact ball bearings, for example, medium or heavy bearing preload is generally selected in the occasion of high load and high rigidity; For some high-speed and high-precision applications, we need to pay attention to the selection of appropriate preload in the early selection of bearings. Generally, light preload is common. Preload is generally divided into light, medium and heavy; In order to facilitate the use of customers, at present, several major bearing manufacturers in the world generally provide bearings with pre grinding bearing end faces and preloading, that is, what we usually call universal paired precision angular contact ball bearings. This type of bearing eliminates the preload adjustment of customers, thus saving installation time. Precision tapered roller bearing In some machine tool applications with heavy load and certain requirements for speed, such as raw grinding of forgings, threading machine of oil pipeline, heavy lathe and milling machine, selecting precision tapered roller bearing is an ideal scheme. Because the roller of tapered roller bearing is designed in line contact, it can provide high rigidity and load for the main shaft; In addition, tapered roller bearing is a pure rolling bearing design, which can well reduce the running torque and heating of the bearing, so as to ensure the speed and accuracy of the main shaft. Because tapered roller bearings can adjust axial preload (clearance) during installation, this allows customers to better adjust the bearing clearance during the entire service life of the bearing.

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05/29/2024

Preventive measures for bearing running noise and overheating

bearing

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05/15/2024

Friction coefficient of bearing

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05/08/2024

Principles to be followed for installation and coordination of eccentric bearing

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Identification of good and bad motor bearings

Causes of bearing waviness and its elimination

Technical knowledge of spindle bearing

Preventive measures for bearing running noise and overheating

Friction coefficient of bearing

Principles to be followed for installation and coordination of eccentric bearing

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