Misunderstanding of the use of lubricating grease during the repair process

Core tips: 1. Butting when installing the cylinder head gasket Some repairmen prefer to apply a layer of butter on the cylinder head gasket when installing the cylinder head gasket, which is considered to increase the engine's tightness. As everyone knows, doing this
 1. Butter when installing the cylinder head gasket

    Some repairers prefer to apply a layer of butter on the cylinder head when installing the cylinder head gasket, which is considered to increase the engine's tightness. As everyone knows, this is not only useless, but harmful. It is well known that the cylinder head gasket is an important sealing material between the engine block and the cylinder head of the automobile. It not only requires strict sealing of the high temperature and high pressure gas generated in the cylinder, but also must seal the pressure and flow rate through the cylinder head and the cylinder body. Cooling water and oil, it is required to pay special attention to the quality of the seal when disassembling the cylinder head gasket.

    If butter is applied to the cylinder head gasket, when the cylinder head bolts are tightened, a part of the butter will be squeezed into the cylinder water channel and the oil passage. When the butter remaining between the cylinder heads is working in the cylinder, some of the oil will flow into the cylinder due to the high temperature. The other part will burn the coke deposits on the joint surface of the cylinder block and the cylinder head. Under the action of high pressure and high temperature, it is easy to break down or burn through the cylinder head gasket, causing the engine to leak. Therefore, do not apply butter when installing the cylinder head gasket.

    2. Diesel car uses gasoline engine oil

    The oil is divided into gasoline engine oil and diesel engine oil. Although gasoline engines and diesel engines also work under high temperature, high pressure, high speed and high load conditions, there is still a big difference between the two. The compression ratio of the diesel engine is more than twice that of the gasoline engine. The main parts are much more affected by high temperature and high pressure than the gasoline engine, so some parts are made of different materials. For example, the gasoline engine main shaft and the connecting rod bearing bush can be made of babbitt alloy with soft material and good corrosion resistance, while the bearing bush of the diesel engine must be made of high-performance materials such as lead bronze or lead alloy, but the corrosion resistance of these materials Poor performance. For this reason, in the refining process of diesel engine oil, more anti-corrosion agent should be added, so that a protective film can be formed on the surface of the bearing pad to reduce the corrosion of the bearing bush and improve the wear resistance. Since the gasoline engine oil does not have such a preservative, if it is added to the diesel engine, the bearing bush is prone to spots, pits and even the unfavorable consequences of peeling off during use, and the oil will quickly become dirty and cause the shaft to burn. The accident occurred. In addition, the sulfur content of diesel oil is larger than that of gasoline. This harmful substance will form sulfuric acid or sulfurous acid during the combustion process, and together with the high-temperature and high-pressure exhaust gas, it will enter the oil sump to accelerate the oxidation and deterioration of the oil, so the diesel engine oil is refined. Some anti-oxidation additives need to be added during the process to make the oil alkaline. If there is acid gas intrusion, it can play a certain neutralization effect, so as not to cause the oil to oxidize and deteriorate too quickly. The gasoline engine oil does not add this additive because it is neutral. If it is used in a diesel engine, it will quickly deteriorate due to the corrosion of the above acid gas. Therefore, do not use gasoline engine oil to fill the diesel engine.

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Locomotive rolling bearing fault generation and diagnosis method

Core Tips: The locomotive rolling bearing fault generation and diagnosis method summary: Introduce the simple diagnosis and precision diagnosis of the rolling bearing of the locomotive, and enumerate the detection cases. Key words: locomotive rolling import
Locomotive rolling bearing fault generation and diagnosis method

    Abstract: This paper introduces the simple diagnosis and precision diagnosis of locomotive rolling imported bearings, and enumerates the detection cases.

    Key words: locomotive rolling imported bearing fault detection
   
    1 Introduction

    As the main components of the locomotive, especially the traction motor and axle box bearing, the imported function plays a decisive role in the safe transportation. When the locomotive runs on the line, once the bearing fails, the whole train will not run, and the transportation line will be blocked. In particular, the passenger trains fail, and the negative impact is even greater. At the same time, once the locomotive bearings fail, it is very difficult to repair the locomotives. Therefore, preventing and reducing the occurrence of locomotive bearing faults is very dangerous for the safe transportation of locomotives. It is important to be able to detect the bearing with hidden troubles before the bearing is loaded, and to ensure that the qualified bearing accessories are on the car is the focus of this paper.

    2 bearing failure

    Severe damage of the bearing is often not caused by a single cause. However, under a combination of several aspects, a vicious cycle occurs under severe operating conditions, resulting in serious burning of the bearing. Therefore, after an accident, it is often difficult to judge What causes it, it also gives us some difficulties in formulating relevant measures. For the convenience of discussion, we first analyze the causes of bearing failures from several aspects.

    2.1 Abnormal wear of the bearing

    2.1.1 When the bearing is used for a period of time, the bearing inner ring, rolling element, cage, outer ring, raceway, etc. will produce certain defects and scars, resulting in poor lubrication of the bearing, causing heat generation of the bearing, long-term heating, resulting in:

    (1) Dilution of bearing lubricants.

    (2) Accelerate the fatigue of the material and reduce the hardness. Due to the above reasons, a vicious cycle is further formed, and the overheating is accelerated to burn the bearing. Severe bearing inner ring displacement, rolling element out of round, collision heat, and finally welded together. Therefore, when running on the line, if the bearing is found to be severely heated and smokes, do not stop, but keep running to the front station, because the overheated bearing is in a molten state at this moment, once it stops cooling, it can no longer walk and block the positive line.
 
    2.1.2 It is very important for the oil supply maintenance of locomotive bearings, especially for the proper amount of oil to ensure that the bearing has good lubrication. It is easy to cause bearing failure due to lack of oil and excessive oiling. Poor lubrication and heat, more often it is easy to cause stirring and overheating, so it is necessary to properly supply oil during maintenance, and the lubricating grease of the bearing is also very important. Once the oil and other impurities and moisture are dropped, it will affect the normal swimming. Gap and build the necessary oil film.

    2.1.3 The bearing is used for too long, which exceeds the service life of the bearing and is prone to fatigue of the material. The strong impact of the material causes the material to deform, causing the roller and the raceway surface to peel off and crush, resulting in poor lubrication. And the vibration is increased.

    2.2 Installation impact on bearings

    2.2.1 The inner clearance of the inner ring of the bearing does not match the interference of the shaft. It is also easy to cause bearing failure. The interference is large. It is easy to cause the inner ring of the bearing to crack due to excessive tensile stress. The interference is too small. It is easy to cause the inner ring of the bearing to "relax".

    2.2.2 Bearing assembly with improper clearance, it is easy to cause bearing failure, small clearance is easy to cause friction between the roller and the raceway. As the temperature rises, the bearing inner ring, rolling element, cage, outer ring The temperature of the end caps is not the same, there is a temperature difference between them, so the amount of expansion is also slightly different, which causes a further reduction of the matching clearance, and the heat generation of the bearing is added. If the clearance is too large, the vibration of the roller is increased, which aggravates the impact of the roller and the raceway. At the same time, the internal load distribution is uneven, the load bearing roller is reduced, and the central roller load is excessive.

    2.2.3 When assembling the bearing, the bearing is not impacted by the copper hammer, which causes the cage to be deformed. The inner and outer rings of the traction motor bearing are not installed correctly or other reasons cause the axial traverse amount to disappear, causing the bearing shaft to squash.

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Extend the maintenance and maintenance of INA combined bearing life cycle

     After the INA combination bearing has been installed, if it is not carefully aligned, alignment may result in additional loads, friction and vibration of the INA combination bearing. These can accelerate fatigue and reduce bearing life and can damage the life of other machine parts. In addition, increased vibration and friction can greatly increase energy consumption and risk of premature failure.
    In order to fully utilize the bearings and maintain their proper performance for a long time, regular maintenance (regular inspection) must be performed. Through proper periodic inspections, early detection of failures and prevention of accidents are important to improve productivity and economy.
1, cleaning
When the INA combination bearing is removed and inspected, the appearance record is first recorded by photography. Also, verify the amount of lubricant remaining and sample the lubricant before cleaning the bearings.
a. The cleaning of the bearing is carried out by rough washing and fine washing, and a metal mesh frame can be placed on the bottom of the used container.
b. When rough washing, remove the grease or adhesive with a brush or the like in the oil. At this time, if the INA combination bearing is rotated in the oil, be careful that the rolling surface will be damaged by foreign matter or the like.
c. When washing finely, slowly rotate the bearing in the oil and carry out it carefully.
The cleaning agent generally used is a neutral non-aqueous diesel oil or kerosene, and a warm alkali liquid or the like is sometimes used as needed. Regardless of which cleaning agent is used, it is often filtered and kept clean.
2, inspection and judgment
In order to judge whether the removed INA combination bearing can be reused, it is necessary to check its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage and seal ring.
3. Basic condition monitoring
During use, the basic external conditions of the US INA combined bearing operation are often monitored, such as temperature, vibration and noise measurements. These regular inspections will identify potential problems early and will prevent unexpected machine stops, enabling production plans, increased plant productivity and efficiency.
4, relubrication
During operation, the bearing is required to have the correct relubrication to perfect its performance. The method of bearing lubrication is divided into grease lubrication and oil lubrication. In order to make the bearing function well, first, choose a lubrication method that suits the conditions of use and the purpose of use. Lubricity of oil lubrication predominates if only lubrication is considered. However, grease lubrication has the advantage of simplifying the structure around the bearing.
5, remove
When the bearing will reach its end of life, it should be replaced. Although the bearing can no longer be used, correctly removing the original INA combined bearing and replacing the new bearing in time can promote the service life of the new INA combined bearing. First, the use of a suitable removal tool will help prevent damage to other machine components. Second, improperly removed technology can be hazardous to the operator.

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Analysis of maintenance technology of IKO needle roller bearing with lubrication

    The function of the IKO bearing fit is to make the stationary and rotating rings of the needle bearing and the stationary part (usually the bearing seat) and the rotating part (usually the shaft) of the mounting part, respectively, to achieve the transfer of the load under rotation. And the basic task of defining the position of the motion system relative to the stationary system.
Needle bearings are required to be fixed in three directions, radial, axial and tangential, on the shaft and in the housing. The radial and tangential positioning is achieved by the tight fit of the bearing ring. The axial positioning is only used in a few cases. The axial position is generally limited by axial limit parts such as end caps and retaining rings. Within the clearance range.
When choosing a fit, you should pay attention to the following four points:
 (1) The circumferential surface of the bearing ring should have good support and uniform force to reduce deformation, and fully exert the bearing capacity of IKO bearing.
 (2) The ferrule cannot slide in the tangential direction in its mating surface, otherwise the mating surface will be damaged.
 (3) The free end bearing must be compatible with the length change of the shaft and the housing bore, that is, it must have the ability to accommodate the axial position to swim within a certain range.
 (4) It must be noted that the needle roller bearing is easy to install and disassemble, saving labor, time and money.
For heavy loads, the grease with a small penetration should be selected for high pressure, and the oil film strength and extreme pressure performance should be high. When selecting grease according to environmental conditions, calcium-based grease is not easily soluble in water and is suitable for drying and low moisture environments. Commonly used greases for IKO bearings include calcium-based greases, sodium-based greases, calcium-based greases, lithium-based greases, aluminum-based greases, and molybdenum disulfide greases. The amount of grease filled in the needle bearing is suitable for filling 1/2-1/3 of the inner space of the bearing. At high speeds, reducing the grease to 1/3 will increase the temperature rise.
The temperature of the bearing, generally the temperature outside the bearing can be inferred. If the oil hole can directly measure the outer ring temperature of the thin-walled bearing, it is more suitable. Usually, the temperature of the bearing rises slowly as the bearing starts to run, and reaches a steady state after 1-2 hours. The normal temperature of the needle bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the IKO bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions.
The bearing is a kind of precision mechanical support component. The bearing user deeply hopes that the bearing mounted on the main machine will not damage and maintain its dynamic performance within the predetermined service period, but the objective facts are sometimes not satisfactory, sudden bearing failure accident. Will cause significant losses to users. Through a large number of bearing failure analysis studies, the short-life or premature loss of precision of needle roller bearings is due to material defects or improper manufacturing, but to a considerable extent, it is not installed and maintained in strict accordance with the requirements of bearing use. Or improper bearing damage or actual load exceeding the rated load of the thin-walled bearing itself causes abnormal damage to the IKO bearing.
Cracking and spalling of the bearing is caused by the cyclic load of the bearing, and the contact surface is prone to fatigue damage. Therefore, in order to improve the service life of the needle bearing, the bearing steel must have high contact fatigue strength.
Hardness is one of the important qualities of IKO bearing quality, and has a direct impact on contact fatigue strength, wear resistance and elastic limit. The hardness of the thin-walled bearing steel in the state of use generally reaches HRC61~65, so that the needle bearing can obtain high contact fatigue strength and wear resistance.

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Commonly used INA self-aligning ball bearing lubrication inspection method

Clean the surface of the machine before inspection, and then remove the parts around the INA unloading bearing. The oil seal is a very fragile part, so be careful to disassemble it. Do not apply excessive force. Then carefully check the oil seal and its surrounding parts. If it has been shown to be bad, be sure to replace it. A bad oil seal will cause alignment. Ball bearing damage and severe equipment downtime.
Apply a little bit of lubricant to the friction between the two fingers. If there is any contaminant, feel it, or apply a layer of lubricant on the back of the hand, then seal the light.
Oil-lubricated INA bearings are vented with old oil and, if possible, refilled with fresh oil and allowed the machine to spin at low speed for a few minutes. As far as possible, the oil collects residual contaminants and then vents the oil. The oil is preferably filtered before use.
Grease-lubricated bearings should be replaced with a cotton joint to any part of the bearing when replacing the grease, as these residual fibers may wedge between the rolling elements and cause damage, especially It is the application of the small-key ball bearing that needs to pay attention to this problem.
Under some special conditions, a small amount of solid lubricant is added to the grease. For example, adding 3~5% of molybdenum disulfide No. 1 can reduce wear and improve the resistance to pressure and heat.
    Viscosity is an important characteristic of lubricating oil. The viscosity directly affects the fluidity of the lubricating oil and the thickness of the oil film formed between the friction surfaces. The viscosity of the lubricating oil at working temperature is generally 12-15 cst. The higher the speed, the lower the viscosity, and the heavier the load, the higher the viscosity.
Oil lubrication methods include:
a. Oil bath lubrication
Oil bath lubrication is the most common lubrication method. It is suitable for low and medium speed lubrication. A part of the self-aligning ball bearing is immersed in the groove. The lubricating oil is brought up by the rotating parts and then flows back to the oil groove. The oil level should be slightly lower. The center of the lowest rolling body.
b. drip lubrication
Drip oil lubrication is suitable for INA bearing parts that need to supply lubricating oil quantitatively. The amount of oil dripping is generally one drop every 3-8 seconds. Excessive oil quantity will cause the bearing temperature to increase.
c. Circulating oil lubrication
The filtered oil is sent to the parts by an oil pump, and the used lubricating oil is filtered and cooled for use. Since the circulating oil can take a certain amount of heat to cool down, this method is suitable for bearing parts with a higher rotational speed.
d. Spray lubrication
The dry compressed air is mixed with the lubricating oil through a sprayer to form an oil mist. During the spraying, the air flow can effectively lower the temperature and prevent the intrusion of impurities. This method is suitable for the lubrication of high speed and high temperature parts.
e. Injection lubrication
The high-pressure oil is injected through the nozzle by the oil pump, and the injected oil flows into the oil groove through the other end. When the bearing rotates at a high speed, the rolling elements and the cage also cause the surrounding air to form a gas flow at a relatively high rotational speed.
When inspecting self-aligning ball bearings, never expose the bearings to contaminants or moisture. If the work is interrupted, the machine should be covered with a piece of oil-paper plastic or similar material.
If the unshielded INA bearing is cleaned without the need for disassembly, the coated INA bearing should be cleaned with a white spirit and then blown with a lint-free cloth or blown with compressed air. Dry (be careful not to let the bearing assembly start to rotate).
Do not clean the bearing with a sealing cover or dustproof; just wipe the outer surface. If the INA bearing is damaged, it needs to be replaced. It is much more economical to replace the self-aligning ball bearing during the regular downtime maintenance period to damage the selected sudden downtime.

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INA roller bearings are maintenance inspection standards

In order to fully utilize INA bearings and maintain their proper performance for a long time, regular maintenance (regular inspection) must be performed. Through proper periodic inspections, early detection of failures and prevention of accidents are important to improve productivity and economy.
Key factors affecting the life of a roller bearing For many rotating machinery products, their service life depends on the life of the bearing components at critical parts of the product. "Maintenance-free" bearings are not one-way bearings that will never be damaged or failed but will not be damaged within a certain period of time. Here the designers calculate the service life of the bearing. The bearing life of the INA bearing is greater than or equal to the overhaul period of the mechanical product. The bearing can be “maintenance free”. When the mechanical product is overhauled, the new bearing can be replaced without using the used bearing. Carry out maintenance.
1, cleaning
When the INA bearing is removed for inspection, the appearance record is first recorded by photography. Also, verify the amount of lubricant remaining and sample the lubricant before cleaning the bearings.
a. The cleaning of the bearing is carried out by rough washing and fine washing, and a metal mesh frame can be placed on the bottom of the used container.
b. When rough washing, remove the grease or adhesive with a brush or the like in the oil. At this time, if the bearing is rotated in the oil, be careful that the rolling surface will be damaged by foreign matter or the like.
c. When washing finely, slowly rotate the bearing in the oil and carry out it carefully.
The cleaning agent generally used is a neutral non-aqueous diesel oil or kerosene, and a warm alkali liquid or the like is sometimes used as needed. Regardless of which cleaning agent is used, it is often filtered and kept clean.
Immediately after cleaning, apply anti-rust oil or anti-rust grease to the roller bearings.
2, inspection and judgment
In order to judge whether the removed bearing can be reused, it is important to check its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage and seal.
Regarding the inspection result, it can be judged by a person who is using a conventional bearing or a proficient bearing.
The criteria for judgment vary depending on mechanical properties and importance, inspection period, and the like. Roller bearings must not be reused if they are damaged and must be replaced.
1) Breakage and defects of bearing components.
2) Peeling of the rolling surface of the raceway.
When the mechanism is running, the part where the one-way bearing is installed is allowed to have a certain temperature. When the body of the mechanism is touched by hand, it should be normal to not feel hot, otherwise the temperature of the INA bearing is too high.
The reasons for the bearing temperature being too high are: the quality of the lubricating oil does not meet the requirements or deteriorates, the viscosity of the lubricating oil is too high; the assembly of the mechanism is too tight (the gap is insufficient); the roller bearing is over-tightened; the bearing race rotates on the shaft or inside the casing; Too large; bearing cage or rolling element fragmentation.
The vibration system consisting of steel, flexibility, mass, damping, etc., determined by the design parameters of the one-way bearing structure, will produce vibrations that are compatible with its mechanics under operating conditions.
The vibration caused by the deviation in the manufacturing process is smaller, and the vibration is smaller. The roundness, waviness and surface roughness of the steel ball surface are the most influential factors on the vibration of each INA bearing component, followed by the shape error and surface roughness of the inner and outer ring channels, and again the roller bearing cleanliness and Lubricant quality, etc.
Operating conditions such as installation conditions, rotational speed, axial load direction, magnitude, etc.

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Rolling noise analysis of NTN bearings

     The rolling sound is due to the rolling of the rolling elements in the raceway when the NTN bearing rotates to excite a smooth and continuous noise, which only attracts attention when its sound pressure level or tone is extremely large. In fact, the sound energy excited by the raceway sound is limited. For example, under normal conditions, the quality of the 6203NTN bearing raceway is 25~27dB. This type of noise is the most typical of single row deep groove ball NTN bearings that can withstand radial loads. It has the following characteristics:
a. Noise and vibration are random;
b. The vibration frequency is above 1 kHz;
c. Regardless of the change in the rotational speed, the main frequency of the noise is almost constant and the sound pressure level increases as the rotational speed increases;
d. When the radial clearance increases, the sound pressure level increases sharply;
e. NTN bearing housing rigidity increases, the lower the total sound pressure level, even if the speed increases, its total sound pressure level does not increase much;
f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication, the viscosity and shape of the soap fiber can affect the noise value.
The source of the rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even with the most advanced manufacturing techniques used to process NTN bearing parts, there are always small geometric errors in the working surface, which causes small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system.
Although the rolling noise of the NTN bearing is unavoidable, the working surface of the part can be processed with high precision, the NTN bearing is correctly selected and the NTN bearing is accurately used to reduce noise and vibration.

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