Bearing in use, pay attention to the main points and bearing cleaning problems
Bearing is an important part of modern mechanical equipment.Its main function is to support the mechanical body of revolution, reduce its friction coefficient during movement, and ensure its accuracy of turning.What should we pay attention to in the bearing?Today sihan bearing belt you know the bearing in use we should pay attention to what problems?
Bearing installation and maintenance
Pay attention to the point
From the perspective of use, the following points should be paid attention to to ensure that the bearing can work reliably:
1, improve the lubrication quality, control the oil pressure, temperature and flow, strengthen the oil filtration.
2. Use fuel oil and lubricating oil in accordance with the regulations.
3. Control the temperature state of the diesel generator set. It is unfavorable to work under the condition of too cold and too hot.In cold weather, the diesel engine should be preheated before starting.
4. The surface quality and geometry of bearings and journal shall be strictly guaranteed.
5, the bearing clearance should be appropriate, the generator set is too large impact, too small lubrication is poor, may burn tile.
How to ensure that the bearings work reliably
Generally speaking, the following points should be paid attention to from the perspective of use:
1.Bearing clearance to be appropriate, too large impact, too small, poor lubrication, may burn tile;
2.The surface quality and geometry of bearings and journal shall be strictly guaranteed.
3.Improve lubrication quality, control oil pressure, temperature and flow, strengthen oil filtration;
4.Use fuel oil and lubricating oil in accordance with the regulations.
In order to give full play to the bearing and maintain its due performance for a long time, it must be effective to do regular maintenance (regular inspection).It is very important to improve productivity and economy to detect faults early and prevent them from happening through proper periodic inspection.
Bearing mounting
Bearing installation is correct, affect the accuracy, life, performance.Therefore, the design and assembly department should fully study the bearing installation.It is expected to be installed according to operating standards.The operating standard items are usually as follows:
(1) clean the bearing and bearing related parts
(2) check the size and finish of related parts
(3) installation
(4) inspection after installing the bearing
(5) supply lubricant
It is desirable that the bearing packing be opened before installation.General grease lubrication, do not clean, directly fill the grease.Lubricating oil lubrication, general also need not clean, but, instrument with or high speed with bearings, etc., to use clean oil wash, remove the rust agent coated on the bearing.Remove the bearing of antirust agent, easy to rust, so can not be placed regardless.Furthermore, the bearing sealed into the grease, do not clean direct use.
Bearing installation method, depending on the bearing structure, fit, conditions and different, in general, because most axis rotation, so the inner ring needs interference fit.Cylindrical bore bearing, multi-purpose press press, or multi-purpose hot loading method.For taper holes, install directly on the taper shaft, or install with sleeve.
When installed to the shell, the general clearance fit is more, the outer ring has interference, usually press in, or there is also a cooling installation after the cold shrinkage fit method.With dry ice as coolant, cold shrinkage to match the installation of the occasion, the moisture in the air will condense on the surface of the bearing.Therefore, the need for appropriate anti-rust measures.
Bearing maintenance
Bearing removal
Disassembly of bearing is regular maintenance, bearing replacement.After disassembly, the disassembly shall be carried out with the same care as the installation if the bearing is to continue to be used or if it is necessary to check the state of the bearing.Take care not to damage the bearing parts, especially the disassembly of interference bearing, the operation is difficult.
It is also important to design and make disassembly tools as needed.During disassembly, according to the drawings, the disassembly method, the sequence, the investigation of the bearing conditions, in order to obtain the safe disassembly operation.
For the outer ring with interference fit, several outer ring extruding screws are arranged on the circumference of the shell in advance with screws. The screw is tightened evenly on one side and removed on the other side.These screw holes are usually covered with blind plugs, tapered roller bearings, and other separated bearings. Several notches are arranged in the shell covering the shoulder.
The disassembly of the inner ring can be pulled out simply by the press.At this point, pay attention to let the inner ring bear its pulling force.Furthermore, the pull-out fixture shown is often used, regardless of the fixture, it must be firmly stuck to the side of the inner ring.For this purpose, it is necessary to consider the size of the shaft block shoulder, or to study the processing of the upper groove at the block shoulder, so as to use the drawing fixture.
Disassembly of inner ring of large bearing adopts oil pressure method.Oil pressure is applied through the oil hole arranged in the bearing to facilitate drawing.For bearings with large width, the oil pressure method and drawing fixture are used together for disassembly.
The inner ring of cylindrical roller bearing can be removed by induction heating.A method of drawing the inner ring by heating it locally in a short time.Induction heating is also used where a large number of such bearing inner rings need to be installed.
How to clean the bearing
When the bearing is removed for inspection, the appearance shall be recorded by means of photography.In addition, confirm the amount of residual lubricant and sample the lubricant before cleaning the bearing.
A. bearing cleaning is divided into rough washing and fine washing, and a metal grid can be placed on the bottom of the container used.
B. When rough washing, use the brush in the oil to remove grease or adhesive.At this time, if the bearings in the oil rotation, attention will be due to foreign bodies and other damage rolling surface.
C. During fine washing, slowly rotate the bearing in the oil and be careful.
The cleaning agent commonly used is neutral without water diesel or kerosene, according to the need sometimes also use warm alkaline solution.No matter what kind of detergent you use, always filter it to keep it clean.
Apply antirust oil or antirust grease to the bearing immediately after cleaning.
Examination and judgment
In order to determine whether the disassembled bearings can be reused, it is important to check the dimensional accuracy, rotational accuracy, internal clearance and mating surfaces, raceway surfaces, retainers and seals.Large bearings can not be rotated by hand, pay attention to check the appearance of rolling body, raceway surface, cage, retaining surface, etc., the higher the importance of the bearing, the more careful inspection.
The cause of rolling bearing heating and its elimination method
Low bearing precision: select the bearing with specified precision grade.
Spindle bending or different center of box hole: repair the spindle or box.
Poor lubrication: select the specified brand of lubrication materials and proper cleaning.
Low assembly quality: improve assembly quality.
Running around the inner shell of the bearing: replace the bearing and related worn parts.
Too much axial force: clean and adjust the clearance of sealing mouth ring between 0.2 and 0.3mm, correct the impeller balance hole diameter and check the static balance value.
Bearing damage: replace bearing.
How to keep the bearing
Bearings are coated with appropriate amount of anti-rust oil and anti-rust paper packaging, as long as the packaging is not damaged, the quality of the bearings will be guaranteed.But for long-term storage, under the condition of humidity below 65% and temperature around 20℃, it is advisable to store it on a shelf 30cm above the ground.In addition, the storage area should avoid direct sunlight or contact with cold walls.
Quality inspection
National standard of bearing
1.National standard of vibration acceleration (commonly known as z-standard)
The standard was established earlier, to measure the vibration acceleration value of the bearing when rotating, to determine the quality of the bearing, divided into Z1, Z2, Z3 from low to high quality grade.At present, bearing manufacturers in China are still using the vibration acceleration value to measure the advantages and disadvantages of the bearing, it simply reflects the fatigue life of the bearing.
2.Vibration velocity standard (commonly known as V standard)
Because the original vibration acceleration standard has not been abolished, so the standard is issued by the ministry of machinery industry standards, is the reference to the European standards combined with the actual situation and needs of our country, to test the bearing vibration speed to determine the quality of the bearing grade (equivalent to the national standard).Divided into V, V1, V2, V3, V4 five quality levels.Various ball bearing quality classes from low to high V, V1, V2, V3, V4;Roll bearings (cylinder, cone) quality grade from low to high for V, V1, V2, V3 four quality grade.
It is used to detect the vibration b velocity of bearing at different frequency segments (low frequency, medium frequency and high frequency) to reflect the bearing quality.It can be generally analyzed whether the bearing has the geometric size problem (such as the steel ring ellipse), the quality problem of raceway/rolling body, the quality problem of the cage, compared with the vibration acceleration to investigate the bearing quality has made a significant improvement.At present, the domestic bearings exported to Europe, the Chinese military and the aerospace industry all carry out bearing quality inspection in accordance with this standard, and at the same time, the quality inspection of European imported bearings and the discrimination of counterfeit imported bearings provide a feasible means.
There are two parallel standards in the bearing quality detection, and the bearings with high quality grade of "z-standard" may not have good quality performance when tested with "v-standard", and there is no correspondence between the two.This in the bearing quality inspection is to pay special attention to.
How to identify the quality of bearings
To identify the quality of equipment bearings, we usually carry out from the following aspects:
1. Whether the outer packing is clear or not
Under general circumstances, the brand that normal manufacturer produces has oneself special designer to undertake design to pack outside, and arrange the factory that produces a condition to pass to make production, accordingly, the package of product no matter from line to color block should be very clear, without ambiguity.
2, whether the stencil is clear
Each bearing product will be printed on the bearing product body its brand name, label, etc.Although the font is very small, but the formal manufacturers of the products are using the stenciling technology to print, and in the process of pressing before not overheating, so its font is small, but deep concave, very clear.And in general, the counterfeit product font is not only fuzzy, due to the printing technology is rough, fonts float on the surface, some can even be easily wiped with the hand or manual traces of serious.
3. Is there any noise
The left hand holds the bearing body sleeve, and the right hand reciprocates the jacket in a small amplitude to make it rotate, listen to whether there is noise during the bearing operation.Due to the backward production conditions of most counterfeit products and manual workshop operation, the bearing body will inevitably be mixed with dust, sand and other impurities in the production process, so when the bearing rotation will appear noise or not smooth operation.This is the key to determining whether a product is a branded product from a legitimate manufacturer with strict production standards and machine operation.
4, the surface
Whether there is a muddy oil trace on the surface requires us to pay special attention when buying imported bearings.Because of the domestic antirust technology and foreign advanced manufacturing countries have a certain gap, so the bearing body antirust treatment is easy to leave a thick trace of oil, feel sticky when the hand contact, and foreign original imported bearings almost no trace of antirust oil can be seen.According to the introduction of the industry, special careful people can smell a special smell on the imported bearings, this is the smell of rust prevention oil.
5. Whether the chamfering is uniform
The chamfering of the so-called bearing, that is, the intersection between the horizontal and vertical surfaces, the counterfeit bearing products due to the limitations of production technology, in these corners of the parts are not satisfactory, this we can easily identify.
6, the packing
Bearing packing includes inner packing and outer packing
After the bearings are manufactured and passed the inspection, they shall be cleaned and rust-proof, and then put into the inner packaging to achieve the purpose of water-proof, moisture-proof, dustproof, shock-proof, maintenance of the quality and accuracy of the bearings, as well as convenient use and sales.
The bearing inner packaging is divided into three categories according to the anti-rust period:
(1) short rustproof period packaging: rustproof period of 3 ~ 6 months, suitable for mass shipment to the same subscriber, in a short time will be put into use bearings.By agreement of both parties, in order to facilitate the use of the principle, the use of simple packaging.
(2) general antirust packaging: antirust period of one year, suitable for general purpose bearings.
(3) long antirust period packaging: antirust period of two years, suitable for special and precision bearings.
The inner packing materials of bearing include polyethylene plastic drum (box), kraft paper, plain and corrugated polyethylene composite paper, paper box, polyethylene or polyethylene plastic film, nylon fastening belt or plastic woven fastening belt, waterproof high-strength plastic belt, gunny bag, etc.All the above materials should be qualified in corrosion resistance test.