Bearing use and cooperation

Core Tip: Use of Bearings Precautions for Use Rolling bearings make precision parts, so they need to be cautious when using them. They use high-performance bearings, if not used properly.
Bearing use
Precautions for use
Rolling bearings make precision parts, so they need to be cautious when using them. They use high-performance bearings. If they are used improperly, they can't achieve the expected performance. Therefore, the following items should be used when using bearings:
▲ Keep the bearings and their surroundings clean. Even if the smiling dust that is invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the bearing.
▲, use the installation carefully, do not allow strong stamping, do not allow the hammer to directly hit the bearing, not allowed to pass the pressure through the rolling elements.
▲ Use appropriate and accurate installation tools, use special tools as much as possible, and try to avoid using cloth and short fibers.
▲, to prevent the corrosion of the bearing, directly take the bearing by hand, to wash the sweat on the hand, and apply high-quality mineral oil before operation, especially in the rainy season and summer to pay attention to rust.
Bearing cooperation
▲, the choice of cooperation
The inner and outer diameters of the rolling bearing are manufactured to standard tolerances. The tightness of the bearing inner ring to the shaft and the outer ring to the seat hole can only be achieved by controlling the tolerance of the journal and the tolerance of the seat hole. The inner ring of the bearing and the shaft are matched by a base hole, and the outer ring of the bearing and the seat hole are made by a shaft.
The correct choice of fit, you must know the actual load conditions, operating temperature and other requirements of the bearing, but it is actually very difficult. Therefore, most of the cases are based on the use of lint selection.
▲, load size
The amount of over-win between the ferrule and the shaft or casing depends on the size of the load. The heavier load uses a larger over-win, and the lighter load uses a smaller over-win.

For more information and purchase please visit: https://www.supplyforever.com

Technical requirements for sliding bearing scraping

Core Tips: 1. Basic Requirements It is necessary to make the journal and the plain bearing evenly and finely contact, and also have a certain matching clearance. 2. Contact angle It is the central angle of the contact surface between the journal and the sliding bearing.
1. Basic requirements
It is necessary to make the journal and the sliding bearing evenly and finely contact, and also have a certain matching clearance.
2, contact angle
It is the central angle of the contact surface between the journal and the sliding bearing.
The contact angle should not be too large or too small. If the contact angle is too small, the pressure of the sliding bearing will increase. In severe cases, the sliding bearing will have a large deformation, accelerate the wear and shorten the service life; if the contact angle is too large, the formation of the oil film will be affected, and good liquid lubrication will not be obtained.
Experimental studies have shown that the limit of the contact angle of the plain bearing is 120°. When the sliding bearing wears to this contact angle, liquid lubrication is destroyed. Therefore, under the premise of not affecting the pressure condition of the sliding bearing, the smaller the contact angle, the better.
From the theoretical analysis of the frictional force distance, when the contact angle is 60°, the friction torque is the smallest. Therefore, it is recommended that for a sliding bearing with a rotational speed higher than 500r/min, the contact angle is 60°, and the sliding bearing with a rotational speed lower than 500r/min is used. The contact angle can be 90° or 60°.
3, the point of contact
The actual contact between the journal and the plain bearing surface can be expressed in terms of the actual number of contact points per unit area. The more the contact points, the finer and more uniform, the better the scratch-off of the sliding bearing, and the worse, the sliding bearing is not good.
Generally speaking, the more fine the contact points, the more difficult it is to scrape. The contact points should be determined in the production according to the performance and working conditions of the sliding bearings. The information listed in the table below is for reference:
Sliding bearing speed
(r/min) contact point
(number of contacts per 25 x 25 mm area)
100 or less 3~5
100~500 10~15
500~1000 15~20
1000~2000 20~25
2000 or more 25 or more
For Class I and Class II precision machines, the above table data can be used. Class III precision machines can be halved according to the above table data.

For more information and purchase please visit: https://www.supplyforever.com

Factors affecting bearing life and control

Core Tips: 1. Material factors affecting bearing life The early failure modes of rolling bearings mainly include cracking, plastic deformation, wear, corrosion and fatigue. Under normal conditions, the main contact is
1. Material factors affecting bearing life

The early failure modes of rolling bearings mainly include cracking, plastic deformation, wear, corrosion and fatigue. Under normal conditions, they are mainly contact fatigue. In addition to the service conditions, the failure of bearing parts is mainly limited by the hardness, strength, toughness, wear resistance, corrosion resistance and internal stress state of the steel. The main intrinsic factors that affect these performance and status are as follows.

1.1, martensite in hardened steel

When the original structure of high carbon chromium steel is granular pearlite, the carbon content of quenching martensite under quenching and low temperature tempering obviously affects the mechanical properties of steel. The strength and toughness are about 0.5%, the contact fatigue life is about 0.55%, and the crush resistance is about 0.42%. When the carbon content of the quenched martensite of GCr15 steel is 0.5% to 0.56%, the anti-failure ability is the strongest. Comprehensive mechanical properties.

It should be noted that the martensite obtained in this case is cryptocrystalline martensite, and the measured carbon content is the average carbon content. In fact, the carbon content in the martensite is not uniform in the micro-region, and the carbon concentration around the carbide is higher than that away from the original ferrite portion of the carbide, so that the temperature at which they begin to undergo martensite transformation is different. Thereby, the growth of the martensite grains and the display of the microscopic morphology are suppressed to become cryptocrystalline martensite. It can avoid the microcracks that are prone to occur in the quenching of high carbon steel, and its substructure is dislocation-type lath martensite with high strength and toughness. Therefore, only when the medium carbon cryptocrystalline martensite is obtained when the high carbon steel is quenched, the bearing parts can obtain the substrate with the best failure resistance.

1.2. Retained austenite in hardened steel

High carbon chromium steel may contain 8% to 20% Ar (residual austenite) after normal quenching. The Ar in the bearing parts has its advantages and disadvantages. In order to eliminate the disadvantages, the Ar content should be appropriate. Since the amount of Ar is mainly related to the austenitizing condition of quenching heating, how much it affects the carbon content of quenched martensite and the amount of undissolved carbide, it is difficult to correctly reflect the influence of Ar amount on mechanical properties. For this reason, the austenitic conditions were fixed and the austenite thermal stabilization treatment process was used to obtain different amounts of Ar. The influence of Ar content on the hardness and contact fatigue life of GCr15 steel after quenching and low temperature tempering was studied. With the increase of austenite content, the hardness and contact fatigue life increase, and then decrease with the peak value, but the peak Ar content is different, the hardness peak appears at about 17% Ar, and the contact fatigue life The peak appears around 9%. When the test load is reduced, the influence of the increase in the amount of Ar on the contact fatigue life is reduced. This is because when the amount of Ar is small, the effect on the strength reduction is small, and the effect of toughening is more obvious. The reason is that when the load is small, a small amount of deformation of Ar occurs, which reduces the stress peak and strengthens the deformed Ar processing strengthening and the stress strain induced martensite transformation. However, if the load is large, the large plastic deformation of Ar and the base will locally generate stress concentration and rupture, thereby reducing the life. It should be noted that the beneficial effect of Ar must be under the stable state of Ar. If it is spontaneously transformed into martensite, the toughness of the steel will be drastically reduced and embrittled.

For more information and purchase please visit: https://www.supplyforever.com

Method for extending the life of a forklift clutch release bearing

Core Tip: The separation bearing of the internal combustion forklift clutch is frequently operated, and the number of damages accounts for a large proportion of the forklift failure. If the driver is properly operated and the maintenance is timely, the bearing can be used for 3 months.
Separation bearings of internal combustion forklift clutches work frequently, and the number of damages accounts for a large proportion of forklift failures. If the driver is properly operated and maintained in a timely manner, the bearing can be used for about 3 months, but it must be replaced when it is repaired. If the driver's technical level is low, the forklift that is driven will have the separation bearing damage almost every month. After the damage, other parts will be removed, such as the separation lever and the clutch plate, so that the material cost of equipment maintenance is obviously improved.

    What is the cause of the clutch release bearing being easily damaged? In practice, although the driver is strictly required to dispense oil every time to the separation bearing, this is not only cumbersome, but the bearing is often damaged. According to the analysis, the high temperature of the engine is transmitted to the separation bearing, and the high-speed rotation of the bearing also generates high temperature. Under such conditions, the oil is difficult to remain in the bearing, the bearing operates continuously under high temperature conditions, and the lubrication condition is not good. The cause of frequent damage.

    In response to the above problems, it has also been tried to heat the bearing in the grease to soak the grease into the bearing. After the treatment, the grease can fill the bearing, but the grease is destroyed due to the high temperature treatment. The amplitude is reduced, the effect is not satisfactory with this method, and the service life of the bearing is not extended. We also used a sharp-mouthed grease gun to directly grease the release bearing. Then installed on the car, after observation and inspection, the service life of the bearing is greatly extended. This method of oiling has received satisfactory results, but the operation is more complicated. Then, we explored the case where the engine was not disassembled and the grease was added. The first test was successful on the 475 C engine, and then the 475C and 480 and 492 engines were tested. Both of them received good results. After repeated practice, improvement, and summing up experience, a relatively simple method of oil injection operation was finally formed. The specific process is as follows:

    (l) The engine does not disintegrate the oil filling method. First open the clutch cover to check the wear of the separated bearing. If it is confirmed that the bearing is not damaged or the wear is not exceeded, remove the clutch pedal, adjust the connecting rod pin, and make the separation bearing and its Return the seat to the last position, fill the hole of the bearing housing with a grease gun until the bearing overflows, then turn the bearing slightly, refill the oil, repeat the above work until there is a little butter around the bearing, then Rotate the bearing and observe the amount of oil. If there is resistance to the rotation of the bearing, it is proved that the bearing is filled with butter. Then remove a small amount of butter that has spilled over the separation housing and reassemble the removed pin and clutch cover.

    (2) The oil filling method of engine disintegration exposes the engine to the assembly of the separation bearing and the bearing housing, and uses a grease gun to grease the small oil hole below the inner ring of the separation bearing housing. When the bearing has a butter overflow, the bearing is rotated until the bearing one There are butter spills in the circle.

For more information and purchase please visit: https://www.supplyforever.com