Installation and maintenance
Pay attention to the points
From the perspective of use, to ensure that the bearing can work reliably, the following points should be paid attention to:
1. Improve the quality of lubrication, control the pressure, temperature and flow of the oil, and strengthen the oil filtration.
2. Use fuel and lubricating oil that meet the requirements.
3. To control the temperature status of the diesel generator set, it is unfavorable to work under the conditions of over-cooling and over-heating. In cold weather, the diesel engine should be warmed up before starting, and the crankshaft should be turned by hand to make the oil enter the friction surface.
4. The surface quality and geometry of bearings and journals should be strictly guaranteed.
5. The bearing clearance should be appropriate. If the generator set is too large, impact will be generated, and if it is too small, the lubrication will be poor and the bushing may be burnt.
How to ensure the reliable operation of bearings
Generally speaking, pay attention to the following points from the perspective of use:
1. The bearing clearance should be appropriate, too large will cause impact, too small will cause poor lubrication, and may burn bushes;
2. The surface quality and geometry of bearings and journals should be strictly guaranteed;
3. Improve the quality of lubrication, control the pressure, temperature and flow of the oil, and strengthen the oil filtration;
4. Use fuel and lubricating oil that meet the requirements.
In order to give full play to the bearing and maintain its due performance for a long time, it is necessary to do a good job of regular maintenance (regular inspection). Through appropriate regular inspections, it is very important to improve productivity and economic efficiency to detect faults early and prevent accidents before they occur.
Install
Whether the bearing is installed correctly affects the accuracy, life and performance. Therefore, the design and assembly department must fully study the bearing installation. Hope to install in accordance with operating standards. The standard operation items are usually as follows:
(1) Clean the bearing and its related parts
(2) Check the size and finishing of related parts
(3) Installation
(4) Inspection after bearing installation
(5) Supply lubricant
It is hoped that the bearing package will be opened just before the installation. General grease lubrication, do not clean, directly fill with grease. Lubricating oil is lubricated, and cleaning is not usually necessary. However, the bearings for instruments or high-speed applications should be washed with clean oil to remove the anti-rust agent coated on the bearings. Bearings with anti-rust agent removed are easy to rust, so they should not be left alone. In addition, bearings that have been packed with grease can be used directly without cleaning.
The installation method of the bearing varies with the bearing structure, fit, and conditions. Generally, because most of the shaft rotates, the inner ring needs an interference fit. Bearings with cylindrical bores are usually pressed in with a press or hot-fitting methods are often used. In the case of a tapered hole, install it directly on the tapered shaft or install it with a sleeve.
When installing to the shell, generally there is a lot of clearance fit, and the outer ring has interference. It is usually pressed in with a press, or there is also a shrink fit method for installation after cooling. When dry ice is used as the coolant, the moisture in the air will condense on the surface of the bearing when the shrink fit is installed. Therefore, appropriate anti-rust measures are required.
maintenance
Disassemble
The disassembly of the bearing is carried out on a regular basis and is carried out when the bearing is replaced. After disassembly, if you continue to use it, or when you need to check the condition of the bearing, the disassembly should be carried out as carefully as the installation. Be careful not to damage the parts of the bearing, especially the disassembly of the interference fit bearing, which is difficult to operate.
It is also very important to design and manufacture disassembly tools according to needs. When disassembling, study the disassembly method and sequence according to the drawings, and investigate the matching conditions of the bearing to ensure that the disassembly operation is foolproof.
Disassembly of the outer ring For the outer ring with interference fit, set several screws for extruding the outer ring on the circumference of the outer ring in advance, tighten the screws evenly on one side, and remove them at the same time. These screw holes are usually covered with blind plugs and separable bearings such as tapered roller bearings. Several cuts are set on the blocking shoulder of the shell. Use a pad to remove it with a press or gently tap it.
The disassembly of the inner ring can be the easiest to pull out with a press. At this time, pay attention to let the inner ring bear its pulling force. Furthermore, the pull-out clamps shown are mostly used. Regardless of the clamps, they must be firmly clamped to the side of the inner ring. For this reason, it is necessary to consider the size of the shoulder of the shaft, or study the processing of the upper groove at the shoulder in order to use the drawing fixture.
The oil pressure method is adopted for the inner ring disassembly of the large bearing. Oil pressure is applied through the oil hole provided in the bearing to make it easy to draw. For bearings with a large width, the hydraulic method and the drawing fixture are used together for disassembly operations.
Induction heating can be used to disassemble the inner ring of cylindrical roller bearings. It is a method to heat the part in a short time to expand the inner ring and then pull it out. Where a large number of these bearing inner rings need to be installed, induction heating is also used.
Cleaning
When disassembling the bearing for inspection, first make a record of the appearance with photography or other methods. In addition, confirm the amount of remaining lubricant and sample the lubricant before cleaning the bearing.
a. The cleaning of the bearing is divided into rough washing and fine washing, and a metal grid can be placed on the bottom of the container in use.
b. When rough washing, use a brush in oil to remove grease or adhesions. If the bearing is rotated in oil at this time, be careful that the rolling surface may be damaged by foreign matter.
c. When fine washing, slowly rotate the bearing in oil, and it must be done carefully.
Commonly used cleaning agents are neutral non-water-containing diesel or kerosene, and sometimes warm lye etc. are used as needed. No matter what kind of cleaning agent is used, it must be filtered frequently to keep it clean.
After cleaning, immediately apply anti-rust oil or anti-rust grease on the bearing.
Inspection and judgment
In order to judge whether the removed bearing can be reused, it is necessary to check its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage, and sealing ring. Because large bearings cannot be rotated by hand, pay attention to checking the appearance of rolling elements, raceway surfaces, cages, rib surfaces, etc. The higher the importance of the bearing, the more careful inspection is required.
The cause of rolling bearing heating and its elimination method
Low bearing accuracy: select bearings with specified accuracy grades.
The spindle is bent or the box hole is not concentric: repair the spindle or box.
Poor lubrication: use the lubricating material of the specified brand and clean it appropriately.
Low assembly quality: Improve assembly quality.
Bearing inner and outer shell running ring: replace the bearing and related wear parts.
Axial force is too large: cleaning and adjusting the sealing ring gap between 0.2mm and 0.3mm, correcting the diameter of the impeller balance hole and verifying the static balance value.
Bearing damage: replace the bearing.
custody
The bearings are coated with an appropriate amount of anti-rust oil and packed with anti-rust paper when they leave the factory. As long as the packaging is not damaged, the quality of the bearings will be guaranteed. However, for long-term storage, it is advisable to store it on a shelf 30cm above the ground under the condition that the humidity is lower than 65% and the temperature is about 20°C. In addition, the storage place should avoid direct sunlight or contact with cold walls.
