Troubleshooting method for temperature and vibration of four row cylindrical roller bearings
Troubleshooting method for temperature and vibration of four row cylindrical roller bearings
2022年6月1日
Installation method and precautions of IKO bearing
Installation method and precautions of IKO bearing
2022年6月3日

Precautions for determining whether ina bearing is overhauled

whether ina bearing The journal matched with the bearing and the hole

  • When judging whether the disassembled ina bearing can be reused, check it after cleaning the linear bearing, and carefully check the state of raceway surface, rolling surface and mating surface, the wear of cage, whether the bearing clearance increases and whether there are damages and abnormalities that affect the decline of dimensional accuracy.
  •  For non separable small ball bearings, use one hand flat end inner ring and rotate the outer ring to confirm whether it is smooth.Precautions for determining whether ina bearing is overhauled
  • For separate bearings such as bearings, the raceway surfaces of rolling elements and outer rings can be inspected respectively.Precautions for determining whether ina bearing is overhauled
  • 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.Precautions for determining whether ina bearing is overhauled
  • When judging whether ina bearing can be reused, it should be determined according to the damage degree, mechanical performance, importance, operating conditions, inspection cycle and other relevant factors of linear bearing. However, if the following defects are found during the inspection, the bearing can not continue to be used and needs to be replaced with a new bearing.Precautions for determining whether ina bearing is overhauled
Precautions for determining whether ina bearing is overhauled

Precautions for determining whether ina bearing is overhauled

  • The matching of bearing and shaft adopts the base hole system, and the matching of bearing and housing adopts the base shaft system. The values of bearing dimensional tolerance and rotation accuracy shall be in accordance with gb307-84.
  • The journal matched with the bearing and the hole in the bearing box shall comply with the provisions of gb1031-83, and the roughness Ra value of the journal shall be less than 1.6 μ m. The roughness Ra value of the hole in the bearing box is less than 2.5 μ m。
  • When making bearing rings and rollers with GCr15 and zgcr15 steel, the hardness value of rings and rollers shall be 61 ~ 65hrc; When GCr15SiMn and zgcr15simn steels are used, the hardness value shall be 60 ~ 64hrc. The inspection method of hardness and the uniformity of hardness of the same part shall be in accordance with jb1255.Precautions for determining whether ina bearing is overhauled
  • Check that the radial clearance and axial clearance of the bearing shall comply with the provisions of gb4604-84.
  • The raceway of the inner and outer rings of the rolling bearing shall be free of peeling and serious wear, and the inner and outer rings shall be free of cracks; The ball shall be free from wear, the cage shall be free from serious deformation, and there shall be no abnormal noise and vibration during rotation. It shall stop gradually when it stops.Precautions for determining whether ina bearing is overhauled
  • For class C tolerance tapered roller bearings, the contact accuracy between the roller and the ring raceway shall be checked by coloring under the action of a certain load. The contact trace shall be continuous, and the contact length shall not be less than 80% of the roller bus.Precautions for determining whether ina bearing is overhauled
  • The service life of the bearing is closely related to manufacturing, assembly and use. It must be done well in each link in order to make the bearing in the running state, so as to prolong the service life of the bearing.Precautions for determining whether ina bearing is overhauled
  • Selection and control of shaft and bearing housing tolerance: the bearing shall rotate flexibly without blocking feeling after being pressed into the bearing. If the rotation tolerance is too large, it indicates that the shaft is not adjusted flexibly. Precautions for determining whether ina bearing is overhauled
  • If there is an obvious “rusty” feeling when the bearing is rotated by hand after being put into the bearing, it may be that the tolerance of the bearing is too large or the roundness of the bearing is not good. Therefore, when controlling the tolerance of shaft and bearing chamber, it is also necessary to control the roundness. At present, many domestic manufacturers only control the tolerance, not the roundness.Precautions for determining whether ina bearing is overhauled
  • Bearing assembly method: because the bearing is a high-precision product, if it is not assembled properly, it is easy to damage the bearing channel and lead to bearing damage. The bearing shall be equipped with a special mold during assembly, which cannot be knocked at will. Precautions for determining whether ina bearing is overhauled
  • When pressing the shaft, only the small ring can be stressed, and when pressing the large ring, only the large ring can be stressed. Pneumatic or hydraulic pressure is required during assembly. During press assembly, the upper and lower molds shall be outside the horizontal state. If there is inclination, the bearing channel will be damaged due to stress and the bearing will make a guide sound.Precautions for determining whether ina bearing is overhauled
  • Prevention of assembly foreign matters: when the bearing is installed on the rotor for dynamic balance, it is easy to enter the iron filings generated during dynamic balance into the bearing, so it is necessary to perform dynamic balance before installing the bearing. In order to facilitate assembly, some manufacturers apply some oil or grease in the bearing chamber for lubrication effect during assembly, but it is often difficult for operators to control the amount. Precautions for determining whether ina bearing is overhauled
  • If more oil or grease is accumulated in the bearing chamber, it is easy to enter the bearing along the shaft when the bearing rotates. The bearing chamber shall not be coated with oil or grease. If it must be coated, it shall be controlled and there shall be no accumulation in the bearing chamber.Precautions for determining whether ina bearing is overhauled
  • Prevention of paint rust: paint rust is often found in sealed motors. The sound of the motor is very good during assembly, but after being placed in the warehouse for some time, the abnormal noise of the motor becomes very large, and there is serious rust when removing the bearing. In the past, many manufacturers thought it was the bearing problem. Precautions for determining whether ina bearing is overhauled
  • After our continuous publicity, now the motor factory has realized that the main problem is the insulating paint. This problem is mainly because the acidic substances volatilized from the insulating paint form corrosive substances at a certain temperature and humidity, which corrodes the bearing channel and leads to bearing damage. At present, the problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time.Precautions for determining whether ina bearing is overhauled

Use appropriate media: ina bearing is overhauled

  • Generally speaking, the rolling bearing itself does not produce noise. 
  • The “bearing noise” usually felt is actually the sound effect of vibration between the bearing and the surrounding structure directly or indirectly. This is why many times noise problems can be regarded as vibration problems involving the whole bearing application.Precautions for determining whether ina bearing is overhauled
  • Excitation caused by the change of the number of loaded rolling elements: when a radial load is loaded on a bearing, the number of loaded rolling elements will change slightly during operation, which causes the deviation of the load direction. The resulting vibration is inevitable, but can be reduced by axial preloading, which is applied to all rolling elements (not applicable to cylindrical roller bearings).Precautions for determining whether ina bearing is overhauled
  • Local damage: a small number of bearing raceways and rolling elements may be damaged due to incorrect operation or installation. During operation, rolling over damaged bearing parts will produce specific vibration frequency. Vibration frequency analysis can identify damaged bearing components. This principle has been applied to condition monitoring equipment to detect bearing damage. To calculate the bearing frequency, refer to the calculation program “bearing frequency”.Precautions for determining whether ina bearing is overhauled
  • Accuracy of relevant parts: when the bearing ring is closely matched with the bearing seat or transmission shaft, the bearing ring may be deformed by matching with the shape of adjacent parts. If deformation occurs, vibration may occur during operation.Precautions for determining whether ina bearing is overhauled
  • Pollutants: if operating in a polluted environment, impurities may enter the bearing and be rolled by the rolling element. The vibration degree depends on the quantity, size and composition of the impurity particles being rolled. Although the typical frequency form will not be generated, a disturbing noise can be heard.Precautions for determining whether ina bearing is overhauled
  • The causes of rolling bearing noise are complex. One is the wear of the mating surfaces of the inner and outer rings of the bearing. Due to this wear, the matching relationship between the bearing and the shell and between the bearing and the shaft is damaged, resulting in the axis deviation from the correct position and abnormal noise when the shaft moves at high speed. Precautions for determining whether ina bearing is overhauled
  • When the bearing is tired, the metal on its surface will peel off, which will also increase the radial clearance of the bearing and produce abnormal noise. In addition, insufficient bearing lubrication, dry friction and bearing breakage will produce abnormal sound. After the bearing is worn and loose, the cage is loose and damaged, which will also produce abnormal noise.Precautions for determining whether ina bearing is overhauled
  • In the daily use of bearings, we need to pay careful attention to their use. Let’s take a look at the nine matters we need to pay attention to.Precautions for determining whether ina bearing is overhauled
  • Riveted parts in the harvester, such as moving knife assembly, are generally made of cold extrusion. They should not be heated during riveting. If heated, the material strength will be reduced. After riveting, the forming punch shall be used to strengthen the firmness of the blade and cutter rod.Precautions for determining whether ina bearing is overhauled
  • Wearing parts, especially pin shaft, pressing plate, sleeve and sizing block, cannot be replaced by adding more butter in maintenance. For example, parts worn to the limit for a long time will shorten the service life of other machinery.Precautions for determining whether ina bearing is overhauled
  • For shaft repair without balancing machine, when balancing is required for repairing various shafts, a thrust bearing can be installed at one end of the shaft and clamped on the three claws of the lathe, and the other end can be supported by the center. Precautions for determining whether ina bearing is overhauled
  • If the lathe is short, the SKF Bearing installed on the shaft at the other end can be clamped by the center frame to correct the balance. However, when balancing the weight, tighten it with screws and try not to balance the weight by electric welding.Precautions for determining whether ina bearing is overhauled
  • In the maintenance, due to the variety of bearing materials and models, it is difficult to purchase, so it can be processed with waste shafts. At present, most shafts in China are mainly made of 45# carbon steel. IF quenching and tempering are required, in case of poor conditions, oxygen and earth furnace can be used to heat the required parts to red and black and place them in salt water, depending on the demand.Precautions for determining whether ina bearing is overhauled
  • When processing sleeve parts, pull the oil groove in the sleeve hole as much as possible. Because it is very difficult to refuel some parts of the harvester, butter and heavy oil can be used where it is difficult to refuel, except nylon sleeve. Where nylon sleeve is used, cast iron, copper and aluminum shall not be used instead, because the nylon sleeve bears certain impact and does not deform.Precautions for determining whether ina bearing is overhauled
  • The key and keyway on the pulley and shaft shall be repaired in advance, and the size of the key shall not be increased, otherwise the strength of the shaft will be affected. The keyway on the shaft can be repaired and welded with electric welding filler, and a key groove can be milled in the opposite direction of the old key. The keyway on the pulley can be inlaid (transition fit). After inlaying, use countersunk screws to tap and tighten the key in the socket seam.Precautions for determining whether ina bearing is overhauled
  • For the maintenance of the hydraulic part of the harvester, remove the distributor and flow reducing valve, and use the air pump to flush the pressure of each pipe fitting. The hydraulic oil shall be filtered and vented during secondary loading. The maintenance of hydraulic assembly is mainly the seal, and the seal shall be replaced after removal.Precautions for determining whether ina bearing is overhauled
  • The influence of cooling process on deformation after metal quenching is also a very important deformation reason. The deformation of hot oil quenching is smaller than that of cold oil quenching, which is generally controlled at 100 ± 20 ℃. The cooling capacity of oil is also crucial to deformation. The stirring mode and speed of quenching affect the deformation. Precautions for determining whether ina bearing is overhauled
  • The faster the cooling speed of metal heat treatment, the more uneven the cooling, the greater the stress, and the greater the variable bearing shape of the die. Pre cooling can be adopted as far as possible on the premise of ensuring the hardness requirements of the die; Precautions for determining whether ina bearing is overhauled
  • The use of staged cooling and quenching can significantly reduce the thermal stress and structural stress during metal quenching, which is an effective method to reduce the deformation of some workpieces with complex shapes; For some workpieces with special complexity or high precision requirements, isothermal quenching can significantly reduce deformation.Precautions for determining whether ina bearing is overhauled
  • On the premise of ensuring the same hardness requirements, try to use oily medium. Experiments and practice have proved that on the premise of no difference in other conditions, the cooling speed of oily medium is slower, while that of aqueous medium is relatively faster. Precautions for determining whether ina bearing is overhauled
  • Moreover, compared with oil medium, the change of water temperature has a greater impact on the cooling characteristics of water medium. Under the same heat treatment conditions, the deformation of oil medium after quenching is relatively small compared with that of water medium bearing.Precautions for determining whether ina bearing is overhauled
  • The structure of parts shall be reasonable:Precautions for determining whether ina bearing is overhauled
  • After metal heat treatment, in the cooling process, the thin part always cools fast and the thick part cools slowly. Under the condition of meeting the actual production needs, the great difference between the thickness of the workpiece should be reduced as far as possible, and the section of the part should be uniform as much as possible, so as to reduce the distortion and cracking tendency in the transition zone due to stress concentration; Precautions for determining whether ina bearing is overhauled
  • The symmetry of structure, material composition and structure of the workpiece shall be maintained as far as possible to reduce the distortion caused by uneven cooling; Sharp edges, corners, grooves, etc. shall be avoided as far as possible, and fillet transition shall be provided at the thickness junction and steps of the workpiece; Try to reduce the asymmetry of hole and slot reinforcement structure on the workpiece; The method of reserving processing quantity is adopted for parts with uneven thickness.Precautions for determining whether ina bearing is overhauled
  • Bearing maintenance: in order to maintain the original performance of the bearing in good condition for as long as possible, it must be maintained and overhauled in order to prevent accidents, ensure the reliability of operation and improve productivity and economy.
  • Maintain the operation standard of corresponding mechanical operation conditions and carry out it regularly. The contents include monitoring the operation status, replenishing or changing the lubricant, and regular disassembly inspection. Maintenance items during operation include bearing rotation sound, vibration, temperature, lubricant state, etc.Precautions for determining whether ina bearing is overhauled
  • Bearing maintenance: bearing cleaning: when disassembling the lower bearing for maintenance, first record the appearance of the bearing, confirm the residual amount of lubricant, and wash the bearing after sampling the lubricant for inspection. As a cleaning agent, gasoline and kerosene are commonly used.Precautions for determining whether ina bearing is overhauled
  • The cleaning of the removed bearing is divided into coarse cleaning and fine cleaning. They are placed in the container respectively. First, put the metal mesh bottom so that the bearing does not directly contact the dirt of the container. 
  • During rough cleaning, if the bearing rotates with dirt, it will damage the rolling surface of the bearing, which should be paid attention to. In the coarse cleaning oil, use a brush to remove the grease and adhesion. After it is roughly clean, turn to fine cleaning.Precautions for determining whether ina bearing is overhauled
  • Fine cleaning is to carefully clean the bearing while rotating in the cleaning oil. In addition, the cleaning oil should always be kept clean.Precautions for determining whether ina bearing is overhauled
  • 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. Precautions for determining whether ina bearing is overhauled
  • 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.Precautions for determining whether ina bearing is overhauled