Rolling bearing

[gǔn dòng zhóu chéng]

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Rolling bearing is used between the running shaft and the shaft seat sliding friction Becomes Rolling friction , thereby reducing Friction loss A precision mechanical element of. Rolling bearings are generally composed of Inner ring 、 Outer ring 、 Rollers and Holder It is composed of four parts. The role of the inner ring is to match with the shaft and rotate with the shaft; The outer ring acts on Bearing pedestal Cooperate to play a supporting role; The rolling element is evenly distributed between the inner ring and the outer ring by means of the cage, and its shape, size and quantity directly affect the service performance and life of the rolling bearing; The cage can make the rolling elements evenly distributed and guide the rolling elements to rotate for lubrication.

Chinese name: Rolling bearing
Foreign name: rolling bearing
Role: Supporting rotating shaft and parts on shaft

Features: Convenient maintenance, reliable operation and starting performance
Disadvantages: Larger radial dimension, poor damping capacity
Applied discipline: Mechanical engineering; Mechanical parts; Rolling bearing

catalog

effect

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form

supporting Rotating shaft and parts on the shaft, and maintain the normal working position and rotation accuracy of the shaft. The rolling bearing is easy to use and maintain, reliable in operation, good in starting performance, and high in bearing capacity at medium speed. And sliding bearing By comparison, rolling bearings have larger radial dimensions, lower damping capacity, lower service life at high speed and greater sound.

structure

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Rolling bearing

The structure of rolling bearing is composed of parts

one Outer ring ——Installed in the bearing seat hole, generally not rotating

two Inner ring ——Installed on the journal, rotating with the shaft

three Rollers ——Core components of rolling bearings

four Holder ——Evenly separate the rolling elements to avoid friction

lubricant It is also considered as the fifth largest part of rolling bearings, which mainly plays the role of lubrication, cooling, cleaning, etc

Rolling bearing characteristics

1. Specialization

In the processing of bearing parts, a large number of special equipment for bearings are used. For example, the ball grinder is used for steel ball processing Grinder And other equipment. Specialization is also reflected in the production of bearing parts, such as steel ball companies specializing in the production of steel balls Miniature bearing Micro bearing factory, etc.

2. Advancement

Due to the requirements of large batch production of bearings, it is possible to use advanced machine tools, tooling and processes. as numerical control machine Three jaw floating chuck and protective atmosphere heat treatment.

3. Automation

The specialization of bearing production provides conditions for its production automation. Fully automatic, semi-automatic special purpose and non automatic Special machine tool And the automatic production line is gradually popularized and applied. Such as automatic heat treatment line and Assembly automatic line Etc.

Basic characteristics

benefit

(1) Significant energy saving. Due to the motion characteristics of rolling bearings friction Far less than sliding bearing , can reduce the power consumption in friction resistance, so the energy-saving effect is significant. From the theoretical analysis and production practice, the rolling bearing is generally used as the main bearing Small ball mill Power saving up to 30%~35%, medium ball mill up to 15%~20%, Large ball mill Power saving can reach 10%~20%. Since the ball mill itself is a major energy consumer in production, this will mean that a considerable amount of cost can be saved.

(2) Convenient maintenance and reliable quality. The rolling bearing can be omitted Babbitt Melting of materials casting and Scraping tile And a series of complex maintenance processes with high technical requirements, as well as oil supply and water supply cooling systems, so the amount of maintenance is greatly reduced. Moreover, because rolling bearings are manufactured by professional manufacturers, their quality is often guaranteed. It also brings convenience to the ball mill manufacturers.

advantage

1、 Frictional resistance Small power consumption, high mechanical efficiency and easy starting;

2. Standardized size, interchangeability, easy installation and disassembly, and convenient maintenance;

3. Compact structure, light weight, and smaller axial size;

4. High precision, large load, small wear and long service life;

5. Some bearings have the performance of automatic centering;

6. It is suitable for mass production, with stable and reliable quality and high production efficiency;

7. The transmission friction torque is much lower than that of hydrodynamic bearings, so the friction temperature rise and power consumption are lower;

8. The starting friction torque is only slightly higher than the rotation friction torque ；

9. The sensitivity of bearing deformation to load change is less than that of hydrodynamic bearing;

10. Only a small amount of lubricant is required for normal operation, and lubricant can be provided for a long time during operation;

11. The axial dimension is smaller than that of conventional hydrodynamic bearings;

12. It can bear radial and thrust combined loads at the same time;

13. In a wide range of load speed, the unique design can obtain excellent performance;

14. Bearing performance is relatively insensitive to fluctuations in load, speed and operating speed.

shortcoming

1. Very noisy.

2、 Bearing pedestal The structure of is relatively complex.

3. High cost.

4. Even if bearings are well lubricated, correctly installed, dust and moisture tight, and operate normally, they will eventually fail due to fatigue of rolling contact surfaces.

performance

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Centering performance

The ability of the bearing to work normally when the shaft centerline is inclined relative to the centerline of the bearing seat hole. Double row centripetal spherical ball bearing and double row centripetal spherical ball bearing roller bearing It has good centering performance. Roller bearings and needle bearing No relative inclination of the inner and outer ring axes is allowed. The allowable inclination angles of various rolling bearings are different, such as single row Radial ball bearing 8 '- 16', 2 ° - 3 ° for double row radial spherical ball bearing, Tapered roller bearing ≤2′。

Limit speed The maximum speed allowed by the bearing under certain load and lubrication conditions. Limit speed and bearing type, size, accuracy Clearance 、 Holder , load and cooling conditions. The working speed of bearing shall be lower than the limit speed. Select high-precision bearings, improve cage structure and materials, and adopt Oil mist lubrication The limiting speed can be increased by improving cooling conditions.

Bearing lubrication

It mainly includes grease lubrication and oil lubrication. Grease lubrication is not easy to leak, easy to seal, long service life, simple maintenance and high oil film strength, but friction torque Larger than oil lubrication, not suitable for high speed. The filling amount of grease in the bearing shall not exceed 1/2~1/3 of the bearing space, otherwise the bearing will be overheated due to excessive mixing lubricant. The oil lubrication cooling effect is good, but the sealing and oil supply devices are complex. The viscosity of oil is generally 0.12-0.2cm/s. The oil with high viscosity should be selected when the load is large and the working temperature is high, and the oil with low viscosity should be selected when the speed is high. Lubrication methods include Oil bath lubrication 、 Drip lubrication 、 Oil mist lubrication 、 Oil injection lubrication And pressure oil supply lubrication, etc. During oil bath lubrication, the oil level shall not be higher than the center of the lowest rolling element. If you press Elastohydrodynamic lubrication If the bearing is designed theoretically and the lubricant viscosity is selected, the contact surface will be separated by oil film. At this time, under the action of stable load, the bearing life can be increased many times.

Modern machines, instruments and other equipment are developing towards high speed, heavy load, precision, lightness and other aspects, which puts forward many new requirements for rolling bearings, such as reducing the size while requiring bearings to maintain or even increase the rated load, adopting new technologies to improve the process, improve manufacturing accuracy, and reduce costs. Universal rolling bearings have been difficult to meet various requirements. Special bearings should be designed and manufactured for machines and equipment with large production capacity. While strengthening standardization, varieties should be increased and the proportion of special bearings should be expanded. The development of modern industry also requires special bearings working under special conditions, such as bearings working in high-speed, high temperature, low temperature, strong magnetic field or in acid, alkali and other media.

classification

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Classification by structure type

Classification of rolling bearings

It can be divided into:

Deep groove ball bearing ， needle bearing ， Angular contact bearing ， Self aligning ball bearing , self-aligning roller bearing, Thrust ball bearing ， thrust self-aligning roller bearing , cylindrical roller bearing, tapered roller bearing, with seat Outer spherical ball bearing wait.

Rolling bearings can be divided into:

1. Deep groove ball bearing

Deep groove ball bearing is simple in structure and convenient in use. It is the bearing with the largest production batch and the widest application range. It is mainly used to bear radial load, and can also bear certain axial load. When the radial clearance of the bearing is increased, it has the function of angular contact bearing and can bear large axial load. It is used in automobiles, tractors, machine tools, motors, water pumps, agricultural machinery, textile machinery, etc.

2. Needle bearing

needle bearing It is equipped with thin and long rollers (the roller length is 3~10 times of the diameter, and the diameter is generally not more than 5mm), so the radial structure is compact. Its inner diameter size and load capacity are the same as those of other types of bearings, and the outer diameter is the smallest. It is especially suitable for supporting structures with limited radial installation size. Bearing without inner ring or Needle roller and cage assembly At this time, the journal surface and housing hole surface matched with the bearing are directly used as the inner and outer rolling surfaces of the bearing. In order to maintain the same load capacity and running performance as the bearing with ring, the hardness, machining accuracy and surface and surface quality of the shaft or housing hole raceway surface should be the same as Bearing ring The raceway of is similar. This kind of bearing can only bear radial load. For example: universal joint shaft, hydraulic pump, sheet mill, rock drill, machine tool gearbox, automobile and tractor gearbox, etc.

3. Angular contact bearing

Angular contact ball bearing The limiting speed is high, which can bear both longitudinal load and axial load, as well as pure axial load. Its axial load capacity is determined by contact angle and increases with the increase of contact angle. Mainly used for: oil pump Air compressor Various transmissions, fuel injection pumps Printing machinery 。

4. Self aligning ball bearing

The self-aligning ball bearing has two rows of steel balls, the inner ring has two raceways, and the outer ring raceway is of internal spherical shape, with the performance of automatic centering. It can automatically compensate the coaxiality error caused by the winding of the shaft and the deformation of the shell, and is applicable to the parts where the supporting seat hole cannot guarantee the strict coaxiality. This kind of bearing mainly bears radial load, while bearing radial load, it can also bear a small amount of axial load, usually not used to bear pure axial load, such as bearing pure axial load, only one row of steel balls are stressed. Mainly used in Combine harvester Agricultural machinery, blowers, paper machines, textile machinery, woodworking machinery, bridge crane wheels and transmission shafts.

5. Self aligning roller bearing

The self-aligning roller bearing has two rows of rollers, which are mainly used to bear the radial load, and can also bear the axial load in any direction. This species Bearing radial load High capacity, especially suitable for working under heavy load or vibration load, but cannot bear pure axial load; Good self-aligning performance, can compensate the same bearing error. Main applications: paper making machinery, speed reducer, railway vehicle axle, steel rolling machine gearbox seat, crusher, various industrial speed reducers, etc.

six Thrust ball bearing

The thrust ball bearing is a separate type bearing. The shaft ring "race" can be separated from the cage steel ball components. The shaft ring is a ring that fits with the shaft, and the seat ring is a ring that fits with the bearing seat hole. There is a gap between the seat ring and the shaft. The thrust ball bearing can only bear axial load, One way thrust ball bearing It can only bear axial load in one direction, Bi directional thrust ball bearing It can bear axial load in two directions. The thrust ball can not limit the radial displacement of the shaft, and the limiting speed is very low. One way thrust ball bearing can limit the axial displacement in one direction of the shaft and housing, and two-way bearing can limit the axial displacement in two directions. It is mainly used in automobile steering mechanism, Machine tool spindle 。

seven Thrust roller bearing

The thrust roller bearing is used to bear the axial load mainly. The axial combined load, but the axial load shall not exceed 55% of the axial load. Compared with other thrust roller bearings, this kind of bearing has lower friction coefficient, higher rotating speed and self-aligning ability. The roller of 29000 type bearing is asymmetric spherical roller, which can reduce the relative sliding of the stick and the raceway in the work. The roller is long, large in diameter, multiple in number and large in load capacity. It is usually lubricated with oil, and can be lubricated with grease in some low speed cases. During design and type selection, priority shall be given. Mainly used in hydraulic generators, crane hooks, and so on.

Rolling bearing

8. Cylindrical roller bearing The roller of cylindrical roller bearing usually consists of Bearing ring The two rib guides, cage, roller and guide ring form an assembly, which can be separated from another bearing ring and belongs to separable bearing. This kind of bearing is easy to install and remove, especially when it is required that the inner and outer rings are interference fit with the shaft and housing. Generally, such bearings are only used to bear radial loads. Only single row bearings with ribs on the inner and outer rings can bear small steady axial loads or large intermittent axial loads. It is mainly used for large motors, Machine tool spindle , axle box, diesel engine crankshaft and automobile, as well as the gearbox to remember

9. Tapered roller bearing

Tapered roller bearings are mainly suitable for bearing the combined radial and axial loads mainly consisting of radial loads Tapered roller bearing with large cone angle It can be used to bear the combined radial and axial loads dominated by axial loads. The bearing is a separate type bearing, and its inner ring (including tapered roller and cage) and outer ring can be installed separately. In the process of installation and use, the radial and axial play of the bearing can be adjusted, and the pre interference installation can also be used for automobile rear axle hub, large machine tool spindle, high-power reducer, axle bearing box, and rollers of conveyor.

10. With seat Outer spherical ball bearing

The spherical ball bearing with seat is composed of spherical ball bearing with seal on both sides and cast (or stamped with steel plate) bearing seat. The Internal Structure of Outer Spherical Ball Bearings and Deep groove ball bearing Same, but the inner ring of this bearing is wider than the outer ring. The outer ring has a truncated outer surface, which can automatically adjust the center when matched with the concave spherical surface of the bearing seat. Usually, there is a gap between the inner hole of this bearing and the shaft, and the inner ring of the bearing is fixed on the shaft with a jack screw, an eccentric sleeve or a set sleeve, and it rotates with the shaft. The bearing with seat is compact in structure, convenient in loading and unloading, perfect in sealing, and suitable for simple support. It is commonly used in mining, metallurgy, agriculture, chemical industry, textile, printing and dyeing, conveying machinery, etc.

Sort by size

According to the size of the outer diameter of the bearing

（1） Miniature bearing ----Bearings with nominal outside diameter less than 26mm.

(2) Small bearings ---- bearings with nominal outside diameter ranging from 28-55mm.

(3) Small and medium-sized bearings - bearings with a nominal outside diameter of 60-115mm.

(4) Medium and large bearings - bearings with a nominal outside diameter of 120-190mm.

(5) Large bearings - bearings with a nominal outside diameter of 200-430mm.

(6) Extra large bearing ---- bearing with a nominal outer diameter of 440-2000mm.

(7) Heavy type bearings - bearings with a nominal outside diameter of more than 2000mm.

Identify bearings

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We usually identify the quality of equipment bearings from the following aspects

Whether the outer packaging is clear. Generally, the brands produced by regular manufacturers have their own special designers to design the outer packaging, and arrange factories with qualified production conditions to produce. Therefore, the product packaging should be very clear and unambiguous from line to color block.

Whether the steel seal is clear

Each bearing product will be printed with its brand words, label, etc. on the bearing product body. Although the font is very small, the products produced by formal manufacturers use steel printing technology to print and emboss before overheating treatment, so the font is small, but deeply concave and very clear. In general, the font of counterfeit products is not only vague, but also floating on the surface due to the rough printing technology. Some can even be easily erased by hand or the manual marks are serious.

Is there any noise

Hold the inner sleeve of the bearing with the left hand, and rotate the outer sleeve with the right hand in a small amplitude to hear whether there is noise during the operation of the bearing. Because most brand copycat The production conditions are backward and the operation is completely manual workshop type. During the production process, impurities such as dust and sand will inevitably be mixed into the bearing body, so there will be noise or unsmooth operation when the bearing rotates. This is the key to judge whether the products are from the brand products of regular manufacturers with strict production standards and machine operation.

Whether there is muddy oil stain on the surface

Whether there are muddy oil stains on the surface requires us to pay special attention when purchasing imported bearings. As there is still a certain gap between domestic anti rust technology and foreign advanced manufacturing countries, it is easy to leave thick oil stains when carrying out anti rust treatment on the bearing body. When touching with hands, it feels sticky and thick, while there is almost no trace of anti rust oil on the imported bearings. According to the insiders, the specially careful people can smell a special smell on the imported bearings, which is the smell of antirust oil.

Whether the chamfer is even

So called bearing Chamfer That is, at the junction of the horizontal and vertical planes, counterfeit bearing products are not satisfactorily processed at these corners due to the limitations of production technology, which can be easily identified.

Bearing packaging

The packaging includes inner packaging and outer packaging. After the bearing is manufactured and inspected as qualified, it shall be cleaned and rust proof before being put into the inner packaging to achieve the purpose of waterproof, moisture-proof, dust-proof, impact proof, maintaining the quality and accuracy of the bearing, and facilitating the use and sales.

The inner packaging of bearings is divided into three categories according to the rust prevention period:

① Short rust proof packaging: the rust proof period is 3~6 months. It is applicable to bearings that are shipped in large quantities to the same subscriber and put into use in a short period of time. According to the agreement of both parties, simple packaging is adopted in the principle of convenient use.

② General rust proof packaging: the rust proof period is one year, suitable for general purpose bearings.

③ Long term anti rust packaging: two years for special and Precision bearing 。

Bearing inner packing materials include polyethylene Plastic cylinder (box), kraft paper, plain and corrugated polyethylene composite paper, paper box, polyethylene or polyethylene plastic film, nylon fastening belt or plastic braided fastening belt, waterproof high-strength plastic belt, linen bag, etc. All the above materials shall be qualified in the corrosion resistance test.

choice

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There are many types of rolling bearings, and the following factors can be considered for selection.

a. Size, direction and nature of load

Rolling bearing

Ball bearings are suitable for bearing light loads, while roller bearings are suitable for bearing heavy loads and impact loads. When the rolling bearing bears pure axial load, it is generally selected thrust bearing ； When the rolling bearing bears pure radial load, it is generally selected Deep groove ball bearing Or short Cylindrical roller bearing ； When the rolling bearing bears a pure radial load and a small axial load, the deep groove ball bearing Angular contact ball bearing 、 Tapered roller bearing And adjusting ball or Spherical Roller Bearings ； When axial load is large, angular contact ball bearing and tapered roller bearing with larger contact angle can be selected, or Radial bearing It is combined with the thrust bearing, which is especially suitable for extremely high axial load or when large axial rigidity is specially required.

b. Allowable speed

There are great differences due to different types of bearings. Generally, bearings with small friction and heat are suitable for high speed. The rolling bearing shall be designed to work below its limit speed.

c. Rigid

When bearing is under load, Bearing ring The elastic deformation will occur at the contact with the rolling element. The deformation is proportional to the load, and its ratio determines the rigidity of the bearing. Generally, the rigidity of the bearing can be improved by preloading the bearing; In addition, the bearing stiffness can also be improved by considering the combination and arrangement of bearings in the bearing support design.

d. Centering performance and installation error

After the bearing is installed in the working position, the poor installation and positioning are often caused by manufacturing errors. At this time, the fishing degree and thermal expansion And other reasons, which make the bearing bear excessive load and cause early damage. Automatic self-aligning bearing can overcome the defects caused by installation errors, so it is suitable for such applications.

e. Installation and removal

Tapered roller bearing needle bearing It belongs to the bearing type with separable inner and outer rings (the so-called separable bearing), which is easy to install and remove.

f. Marketability

Even the bearings listed in the product catalog may not be sold in the market; On the contrary, some bearings not listed in the product catalog are produced in large quantities. Therefore, it should be clear whether the bearings used are easily available.

Dimensional inspection

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As the thin-walled outer ring may not be round during processing, the dimensional accuracy of the stamping needle roller bearing cannot be inspected before installation. The necessary geometric accuracy of the bearing can only be achieved when it is pressed into the bearing housing hole with the recommended tolerance limit.

The inspection method for the diameter deviation of the inscribed circle of the needle roller bearing is as follows:

(1) Press the bearing into the ring gauge (wall thickness ≥ 20mm), and the size of the ring gauge shall be as specified in Table 2.

(2) Check the diameter of the inscribed circle of the bearing with a cylindrical go gauge and a non go gauge.

Load and life

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The total number of revolutions or total working hours at a certain speed before contact fatigue wear of any element in the rolling bearing is called bearing life. The service life of rolling bearings varies greatly. The service life of bearings produced in the same batch can vary several times or even tens of times when they are operated under the same conditions. 90% of bearings in the same batch can reach or exceed the total revolutions (or working hours) before fatigue peeling Rated life L 。

The load that can be borne when the rated life is 1 million revolutions is the rated dynamic load load C 。 When the sum of the plastic deformation at the contact between the roller bearing the maximum load and the raceway reaches one ten thousandth of the diameter of the roller, the load that can be borne is the rated static load C 0。 The greater the rated load, the stronger the load capacity of the bearing. Radial bearing The rated load of is pure radial load, thrust bearing The rated load of is pure Axial load 。 The actual load of the bearing is often different from the rated load, which must be converted into equivalent load.

Under equivalent dynamic load P Under the action, the life of the bearing is the same as that under the actual load condition. Under equivalent static load P Under the action of 0, the total plastic deformation at the contact between the roller with the largest load and the raceway is the same as that under the actual load condition. The relationship between rated life, rated dynamic load and equivalent dynamic load of bearing is

formula

Where ε Is the life index: ball bearing ε =3. Roller bearing ε =10/3。 When selecting bearings, the period of intermediate repair or overhaul of the machine is usually taken as the expected life of bearings. For example, 500~2000 hours for infrequently used equipment; 20000~30000 hours for machines that work 8 hours a day continuously; The machine that has been used continuously for 24 hours every day is 40000~100000 hours. In fact, only a few bearings are damaged when the expected life is reached.

Code

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Rolling bearing code is a combination of letters and numbers to indicate bearing structure, size Tolerance class , technical performance, etc. The national standard GB/T272-93 stipulates that the bearing code consists of three parts: pre code, basic code and post code. Basic code is the basis of bearing code. The pre code and post code are supplements to the bearing code. They can only be used when there are special requirements for the bearing structure, shape, material, tolerance grade, technical requirements, etc. Generally, they can be partially or completely omitted

Rolling bearing

a. Basic code

The basic code indicates the basic type, structure and size of the bearing. It consists of bearing type code, size series code and inner diameter code.

a1、 Bearing type codes use numbers or letters to indicate different types of bearings. See the database for details.

a2、 The dimension series code consists of two digits. The first digit represents the width series（ Radial bearing ）Or height series（ thrust bearing ）, the last digit represents the diameter series. The dimension series indicates that bearings with the same inner diameter can have different outer diameters, and the same outer diameter has different widths (or heights), so as to meet the bearing capacity of different requirements.

a3、 The inner diameter code indicates the size of the nominal inner diameter of the bearing, which is represented by numbers.

Example: Bearing 2 32 24

2 - Type code, Spherical Roller Bearings ； 32 - Size series code; 24 - ID code, d=120mm;

Example: bearing 6208-2Z/P6

6 - Type code, Deep groove ball bearing ； 2 - Size series code; 08 ID code, d=40mm;

2Z bearing with dust cover at both ends; P6 - Tolerance level meets the standard level 6

L Detachable inner or outer ring of separable bearing

R Bearing without detachable inner ring or outer ring (needle bearing is only applicable to NA type)

K Roller and cage assembly

WS thrust cylindrical roller bearing Axle ring

GS Thrust cylindrical roller bearing race^[1]

Routine maintenance

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1、 Are there requirements for the installation surface and installation site?

yes. If there are iron filings, burrs, dust and other foreign matters entering the bearing, the bearing will generate noise and vibration during operation, and even damage the raceway and rolling element. Therefore, before installing the bearing, you must ensure that the installation surface and installation environment are clean.

2、 Must bearings be cleaned before installation?

The bearing surface is coated with antirust oil. You must carefully clean it with clean gasoline or kerosene, and then apply clean high-quality or high-speed high-temperature lubricating grease before installation and use. Cleanliness has great influence on bearing life and vibration noise. But we want to remind you that totally enclosed bearings do not need to be cleaned and oiled.

3、 How to select grease?

Rolling bearing

Lubrication has a very important impact on the operation and life of bearings. Here is a brief introduction to the selection grease General principles of. Grease consists of Base oil 、 Thickening agent And additives. The performance of greases of different types and different brands of the same type varies greatly, and the allowable rotation limits are different. Pay attention to the selection. The performance of grease is mainly determined by base oil. Generally, low viscosity base oil is suitable for low temperature and high speed, and high viscosity base oil is suitable for high temperature and high load. Thickener is also related to the lubrication performance, and the water resistance of the thickener determines the Water resistance 。 In principle, greases of different brands cannot be mixed, and even greases with the same thickening agent will have bad effects on each other due to different additives.

4、 When lubricating bearings, is it better to apply more grease?

When lubricating bearings, the more grease you apply, the better. This is a common misconception. Excessive grease in the bearing and bearing chamber will cause excessive mixing of grease, resulting in extremely high temperature. The amount of lubricant filled in the bearing should be 1/2~1/3 of the bearing internal space, and should be reduced to 1/3 at high speed.

5、 How to install and remove?

During installation, do not directly hammer the bearing end face and the non stressed surface. Use blocks, sleeves or other installation tools (tooling) to make the bearing evenly stressed. Do not install the bearing by power transmission through rolling bodies. If the mounting surface is coated with lubricating oil, the installation will be more smooth. If the fit interference is large, the bearing should be put into the mineral oil and heated to 80~90 ℃ before installation as soon as possible, and the oil temperature should be strictly controlled not to exceed 100 ℃ to prevent tempering Effect hardness reduction and influence size recovery. In case of difficulty in disassembly, it is recommended that you use the disassembly tool to pull outward while carefully pouring hot oil on the inner ring. The heat will cause the inner ring of the bearing to expand, making it easier to fall off.

6、 Is the smaller the radial clearance of the bearing the better?

Not all bearings require the minimum working clearance. You must select the appropriate clearance according to the conditions. In the national standard 4604-93, the radial clearance of rolling bearing is divided into five groups - group 2, group 0, group 3, group 4, and group 5. The clearance values are from small to large, in which group 0 is the standard clearance. The basic radial clearance group is applicable to general operating conditions, conventional temperatures and commonly used interference fit; For bearings working under special conditions such as high temperature, high speed, low noise and low friction, large radial clearance should be selected; Smaller radial clearance should be selected for precision spindle and bearing for machine tool spindle; For roller bearings, a small amount of working clearance can be maintained. In addition, there is no clearance for separated bearings; Finally, the working clearance of the bearing after installation is smaller than the original clearance before installation, because the bearing must bear a certain load rotation, as well as the elastic deformation caused by bearing matching and load.

difference

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Basic differences

Rolling bearings and sliding bearing The first difference is that in structure, the rolling bearing is supported by the rotation of the rolling element, and the contact part is a point. The more rolling elements, the more contact points; The sliding bearing supports the rotating shaft by a smooth surface, so the contact part is a surface. Secondly, the movement mode of rolling bearing is rolling; The motion mode of sliding bearing is sliding, so the friction situation is completely different.

sliding bearing

Sliding bearing, which works under sliding friction. The sliding bearing works stably, reliably and noiseless. Under the condition of liquid lubrication, the sliding surface is separated by the lubricating oil without direct contact, which can also greatly reduce the friction loss and surface wear. The oil film also has a certain vibration absorption capacity. But the starting friction resistance is large. The part of the shaft supported by the bearing is called the journal, and the parts matching the journal are called bearing shells.

The antifriction material layer cast on the inner surface of the bearing pad to improve the friction property of the bearing pad surface is called Bearing liner 。 The materials of bearing shells and bearing liners are collectively referred to as sliding bearing Material Science. Common sliding bearing materials are Bearing alloy (Also called Babbitt or white metal ）、 Wear resistant cast iron , copper base and Aluminium base alloy 、 Powder metallurgy material , plastic, rubber, hardwood and carbon- graphite ， teflon (PTFE), modified Polyoxymethylene (POM), etc. The sliding bearing is generally used in low-speed and heavy load working conditions, or in operation parts where maintenance and lubricating oil filling are difficult.

Rolling bearing

In rolling bearing Radial bearing (mainly bearing radial force) Inner ring 、 Outer ring 、 Rollers And Rollers Holder 4 parts. The inner ring is tightly sleeved on the journal and rotates with the shaft, and the outer ring is installed in the bearing seat hole. Raceways are made on the outer circumference of the inner ring and the inner circumference of the outer ring. When the inner and outer rings rotate relative to each other, the rolling body rolls on the raceway of the inner and outer rings. They are separated by the cage to avoid mutual friction. thrust bearing It is divided into tight ring and live ring. The tight ring is tightly sleeved with the shaft, and the live ring is supported on the bearing seat. Ferrules and rolling elements are usually of high strength and good wear resistance Rolling bearing steel The surface hardness after quenching shall reach HRC60~65. Cages are usually made of mild steel by stamping, or copper alloy cloth sandwiched bakelite or plastic.

Common faults

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Common faults of rolling bearing

There are two kinds of fault phenomena of rolling bearings. One is that the temperature of the bearing installation part is too high, and the other is that there is noise in the bearing operation.

1. The bearing temperature is too high

When the mechanism is running, a certain temperature is allowed at the position where the bearing is installed. When touching the mechanism shell with hands, it should be normal not to feel hot, otherwise it indicates that the bearing temperature is too high.

The reason for high bearing temperature is that the quality of lubricating oil does not meet the requirements or is deteriorated, Viscosity of lubricating oil Too high; The mechanism assembly is too tight (insufficient clearance); The bearing assembly is too tight; The bearing race rotates on the shaft or in the housing; Excessive load; Bearing cage or rolling element is broken.

two Bearing noise

The rolling bearing is allowed to make slight running noise during operation. If the noise is too loud or there is abnormal noise or impact, it indicates that the bearing is faulty.

The reasons for the noise of rolling bearings are complex. One is the wear of the mating surfaces of the inner and outer rings of bearings. Because of this wear, the matching relationship between the bearing and the housing, and between the bearing and the shaft is destroyed, which causes the axis to deviate from the correct position and produces abnormal noise when the shaft is moving at high speed. When the bearing is fatigued, the metal on its surface will peel off, which will also increase the radial clearance of the bearing and produce abnormal sound. In addition, abnormal sound will be generated due to insufficient lubrication of bearings, dry friction and bearing breakage. After the bearing is worn and loose, the cage is loose and damaged, which will also produce abnormal noise.

3. Bearing wear

Rolling bearing wear is a common equipment problem during the use of the shaft, which is mainly caused by the metal characteristics of the shaft: although the metal has high hardness, it has poor yielding ability (it cannot be recovered after deformation), poor impact resistance, and poor fatigue resistance, so it is easy to cause adhesive wear 、 abrasive wear , fatigue wear Fretting wear Etc. Most of the shaft wear is not easy to detect. It can only be detected when the machine is at high temperature, has a large bounce, and makes abnormal noise. However, when people find out, most of the rolling shafts have been worn, causing the machine to stop.

Proper use

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1. Disassembly and assembly of bearing

The bearing shall be cleaned before installation. During installation, the auxiliary bearing shall be pressed in straightly and evenly with special tools. Do not knock it with a hammer. In particular, it is forbidden to knock it directly on the bearing. When the fit between the bearing race and the seat hole is loose, the seat hole should be repaired or the bearing should be replaced. Do not use reluctantly by pitting the bearing mating surface or padding with copper. When disassembling the bearing, use a suitable puller to pull out the bearing, and do not knock the bearing with a chisel, hammer, etc.

2. Bearing lubrication

Lubricants commonly used in rolling bearings are lubricating oil and grease. When the circumferential speed of the shaft is less than 4-5m/s, or the parts on the vehicle that cannot be lubricated with lubricating oil Grease lubrication 。 The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to lose, and it is not affected by temperature, so it can be used for a long time after adding grease once.

Two problems should be paid attention to when using lubricating grease. One is to select the lubricating grease of appropriate brand according to the requirements of the vehicle manual. For example, nano grease is not suitable for automobile water pump bearings because of its poor water resistance. Second, the lubricating grease in the bearing should be appropriate. Generally, only 1/2-l/3 of the bearing cavity should be filled. Too much grease is not only useless, but also increases the running resistance of the bearing, making it heat up. Pay special attention to the car Hub bearing It is necessary to promote "empty hub lubrication", that is, only apply an appropriate amount of grease on the bearing. Otherwise, not only waste and poor heat dissipation, but also make the grease overflow when heated, which may affect the braking performance.

The advantages of lubricating oil lubrication are small friction resistance and heat dissipation. It is mainly used for bearings with high speed and high working environment temperature. The brand of lubricating oil shall be selected according to the requirements of the vehicle manual, and it shall be timely replaced according to the vehicle maintenance cycle. After the old oil is drained, the mechanism shall be cleaned and then new oil shall be added. The oil shall be added to the specified marking or flush with the oil filler (depending on the specific structure and requirements of the vehicle), and no more oil shall be added.

Solution

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Traditional maintenance methods

In China, repair welding, ball replacement, pitting and other methods are generally used for rolling shaft wear, but the material of the shaft is 45 # steel (Quenching and tempering treatment), if only surfacing treatment is used, welding internal stress will be generated. Under heavy load or high-speed operation, cracks and even fractures may occur at the shaft shoulder Stress relief annealing , it is difficult to operate, and the processing cycle is long, and the maintenance cost is high; When the shaft material is HT200, cast iron welding is not ideal. Some enterprises with high maintenance technology will adopt Brush plating 、 Laser welding , micro arc welding and even Cold welding These maintenance technologies often require high requirements and high costs.

Calculation method of fault frequency

Failure frequency of outer ring of rolling bearing: BPFOR ∨ 0.4Nn

Failure frequency of inner ring of rolling bearing: BPFIr ∨ 0.6Nn

Failure frequency of rolling bearing cage: FTFr ∨ 0.4N

Failure frequency of bearing outer ring: BPFOe ∨ N (0.5n-1.2)

Fault frequency of bearing inner ring: BPFIe ∨ N (0.5n+1.2)

Bearing rolling element failure frequency: BSFe ∨ N (0.2n-1.2/n)

Fault frequency of bearing cage: FTFe ∨ N (0.5-1.2/n)

Above symbol: n=number of scrolls. N=shaft speed.

notes : 1. The rolling bearing does not slide; 2. The geometric dimension of rolling bearing has not changed; 3. The outer ring of the bearing is fixed and does not rotate.

Latest maintenance methods

For the above repair technology, it is not very common in European, American, Japanese and Korean enterprises, and developed countries generally use Polymer composites Technology, nanotechnology and polymer technology can be operated on site, which effectively improves the maintenance efficiency and reduces the maintenance cost and intensity. Among them, the most widely used Meijiahua Fushi Blue Technical system. Compared with traditional technologies, polymer composites not only have the strength and hardness required by metals, but also have the flexibility (variable relationship) that metals do not have, which can maximize the size matching of repair parts and matching parts; At the same time, the composite material can effectively absorb the impact of external forces, greatly resolve and offset the radial impact of the bearing on the shaft, and avoid the possibility of clearance, which also avoids the secondary wear caused by the increased clearance of the equipment.

Status and role

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Rolling bearing is an important mechanical basic component widely used in various fields of national economy and national defense.

The invention of rolling bearing has a long history. According to the archaeological relics found in Yongji County, Shanxi Province, China, as early as 221~2007 BC (Qin Dynasty), bronze rolling bearings had been produced; According to the archaeological finds in Lake Nimi in Italy, bronze rolling bearings also existed in 12-41 AD. The birth of modern bearing industry is marked by the world's first ball grinder invented by Germany in 1883, and the era of industrial production of steel balls. With the booming development of bicycle, automobile and other industries during the second industrial revolution, rolling bearings have gradually become a highly professional industry worldwide, playing a very important role in modern industry.

The importance of rolling bearings is mainly reflected in the following aspects:

(1) In the national economy, rolling bearings are called "industrial joints". Bearing industry, as the basic and backbone industry of machinery industry, its development level often represents or restricts the development level of a country's machinery industry and other related industries. In Japan, people often call bearings the food of industry. Bearing industry is called "the core industry of machinery industry" and "the basic industry to improve national life". It is protected and supported by the revitalization policy of the Japanese government and is one of the 14 "specific machinery industry" industries. In China, rolling bearing is one of the 11 categories of specific revitalization machinery products determined by the state, and 33 bearing enterprises are listed as specific revitalization industries. Among the 520 key enterprises newly determined by the state, 6 are in the bearing industry. In the Catalogue of Industries, Products and Technologies Encouraged by the State at Present, car bearings, railway rolling stock Precision bearing and High speed bearing Manufacturing is included.

(2) In the national defense industry, rolling bearings are essential armaments. Without bearings, missiles cannot be launched, aircraft cannot go to the sky, warships cannot go to sea, tanks cannot go to attack Bearings are important or core components in many military equipment; In the war, the bearing factory is one of the key targets of the hostile countries; During the Cold War, the special equipment for bearings was once the focus of Western countries Socialist country One of the prohibited goods under economic blockade. So far, many bearing products and technologies are still included in the scope of technical blockade by many military powers.

(3) In terms of technical position, bearing steel is the steel with the most strict technical indicators among various alloy steels. It is universally recognized that the smelting level of bearing steel is a symbol of a country's metallurgical technology level. In China, among many special steels such as stainless steel, high-speed steel, gear steel, valve steel, spring steel and so on, bearing steel is one of the few steel types that need to issue production licenses so far. Rolling bearings are also many new materials, such as engineering ceramics engineering plastic Important application fields.

Rolling bearing industry is one of the earliest industrial fields to carry out standardization activities and adopt reliability technology. As early as 1949, the classical theory of rolling bearing fatigue life and reliability was established. In 1963, it was incorporated into the international standard ISO281:1963.

Development of Bearing Industry in China

With the implementation of China's reform and opening up policy, a large number of foreign bearing products in the field of advanced technology have entered China. Due to the political influence in the early days of the founding of New China, the spread of foreign civil bearing technology and product sales were once blocked, but ultimately because of China's huge consumer market and the rise of national industry, Most famous bearing brands abroad have set up subsidiaries or even production plants in China. Although the domestic bearing industry has made remarkable progress and improvement, there is still a big gap in the promotion of technical quality and product after-sales maintenance concept. In general, the commercial output value is inherently weak compared with foreign bearings, and the popularity of high-end bearing domestic industrial industry needs to be expanded and developed.

Due to the special period of China's domestic development, Market economy system The sale of lower bearing products is particularly chaotic. There are a large number of large and small dealers engaged in various types of imported and domestic bearings in China. Due to the large market demand, all walks of life are inseparable from bearings, which has created a phenomenon of "matching the number of bearings" in China's unique bearing products. According to different enterprises (except the military) In China, from imported high-quality bearing products to general domestic bearings, the market prices are extremely different and jittery.

Relevant national standards

GB/T 28268-2012 Technical Conditions for Stamped Cages of Rolling Bearings

GB/T 27556-2011 Rolling Bearings Radial bearing Locating groove size and tolerance

GB/T 273.1-2011 Rolling Bearings - Overall Outline Dimensions - Part 1: Tapered Roller Bearings

GB/T 20060-2011 Rolling bearings Cylindrical roller bearings Dimensions of separable oblique retaining rings

GB/T 27558-2011 Rolling Bearings Classification of Linear Motion Rolling Bearings

GB/T 27557-2011 Rolling Bearings Linear Motion Rolling Bearings Code Method

GB/T 27560-2011 Rolling Bearings Outer spherical ball bearing Technical conditions of casting base

GB/T 27554-2011 Rolling Bearings - Designation Method for Spherical Ball Bearings with Pedestals

GB/T 27555-2011 Rolling Bearings - Specification for Spherical Ball Bearings with Pedestals

GB/T 27559-2011 Rolling Bearings Machine tool spindle Cylindrical roller bearing

GB/T 6391-2010 Rated Dynamic Load and Rated Life of Rolling Bearings

GB/T 25766-2010 Rolling Bearings - External Spherical Ball Bearings - Radial Clearance

GB/T 25765-2010 Rolling Bearings Ball Bearings for Automotive Gearboxes

GB/T 25764-2010 Rolling Bearings Roller Bearings for Automobile Gearboxes

GB/T 25767-2010 Rolling Bearing Tapered Roller

GB/T 25769-2010 Measuring Method for Radial Clearance of Rolling Bearings

GB/T 25760-2010 Rolling Bearings Needle Roller and Thrust Ball Combined Bearings Boundary Dimensions

GB/T 25768-2010 Rolling Bearings Needle Roller and Bi directional Thrust Cylindrical Roller Combination Bearings

GB/T 25761-2010 Rolling Bearings Needle Roller and Angular Contact Ball Combination Bearings Boundary Dimensions

GB/T 25772-2010 Rolling Bearings Bearings for Passenger Trains

GB/T 25771-2010 Rolling Bearings Railway Locomotive Bearings

GB/T 25770-2010 Rolling Bearings Railway Freight Car Bearings

GB/T 308.2-2010 Rolling Bearing Ball Part 2: Ceramic Ball

GB/T 25763-2010 Rolling Bearings Needle Bearings for Automobile Gearboxes

GB/T 25762-2010 Rolling Bearings for Motorcycle Connecting Rod Supports Needle roller and cage assembly

GB/T 25510-2010 Reference Dictionary of Rolling Bearings for Mechanical Systems and General Components

GB/T 7810-1995 Rolling Bearing Belt Seat Outer spherical ball bearing Overall dimension

GB/T 7809-1995 Rolling Bearings -- External Spherical Ball Bearings -- Boundary Dimensions

GB/T 24610.4-2009 Rolling Bearings - Vibration Measurement Methods - Part 4: Cylindrical Roller Bearings with Cylindrical Holes and Cylindrical Outer Surfaces

GB/T 24611-2009 Rolling Bearing Damage and Failure Terms, Characteristics and Causes

GB/T 24610.3-2009 Rolling Bearings - Vibration Measurement Methods - Part 3: Cylindrical Bearings with Cylindrical Holes and Cylindrical Outer Surfaces Spherical Roller Bearings And tapered roller bearings

GB/T 24610.2-2009 Rolling Bearings - Vibration Measurement Methods - Part 2: Radial Ball Bearings with Cylindrical Holes and Cylindrical Outer Surfaces

GB/T 24610.1-2009 Rolling Bearing Vibration Measurement Methods Part 1: Foundation

GB/T 24609-2009 Calculation Method and Coefficient of Rated Thermal Speed of Rolling Bearings

GB/T 24608-2009 Inspection Rules for Rolling Bearings and Commodity Parts

GB/T 24607-2009 Rolling Bearing Life and Reliability test And assessment

GB/T 24606-2009 Non destructive Testing of Rolling Bearings Magnetic Particle Testing

GB/T 24605-2009 Rolling Bearing Product Marks

GB/T 24604-2009 Thrust Force for Screw of Rolling Bearing Machine Tools Angular contact ball bearing

GB/T 12764-2009 Rolling Bearings without Inner Race Stamped outer ring needle bearing Overall dimensions and tolerances

GB/T 7218-1995 Rolling bearings - Boundary dimensions of miniature radial ball bearings with flanged outer rings

GB/T 21559.2-2008 Rolling Bearings Linear Motion Rolling Bearings Part 2: Rated Static Load

GB/T 271-2008 Classification of Rolling Bearings

GB/T 299-2008 Rolling Bearings - Double row tapered roller bearings - Boundary dimensions

GB/T 21559.1-2008 Rolling Bearings Linear Motion Rolling Bearings Part 1: Rated Dynamic Load and Rated Life

GB/T 7813-2008 Rolling Bearings Split Vertical Bearing Pedestals Boundary Dimensions

GB/T 300-2008 Rolling Bearings Four row tapered roller bearing Overall dimension

GB/T 5859-2008 Rolling Bearings thrust self-aligning roller bearing Overall dimension

GB/T 292-2007 Rolling Bearings - Angular Contact Ball Bearings - Boundary Dimensions

GB/T 283-2007 Rolling Bearings Cylindrical Roller Bearings Boundary Dimensions

GB/T 6445-2007 Rolling Bearing Rollers needle bearing Overall dimensions and tolerances

GB/T 7811-2007 Rolling bearing parameters Symbol

GB/T 9160.1-2006 Rolling Bearing Accessories Part 1: Tapered Bushing

GB/T 4663-1994 Rolling Bearings thrust cylindrical roller bearing Overall dimension

GB/T 5801-2006 Rolling Bearings 48, 49 and 69 Dimension Series needle bearing Overall dimensions and tolerances

GB/T 20056-2006 Radial Bearing Needle roller and cage assembly Dimension and Tolerance

GB/T 20058-2006 Rolling Bearings Single row angular contact ball bearing Chamfer size of outer ring non thrust end

GB/T 273.2-2006 Rolling Bearings thrust bearing Overall dimension plan

GB/T 4604-2006 Rolling Bearing Radial Clearance

GB/T 9160.2-2006 Rolling Bearing Accessories Part 2: Lock nut And locking device

GB/T 20057-2006 Rolling Bearings cylindrical roller bearing Chamfer size of flat retaining ring and ring without flange

GB/T 3882-1995 Rolling Bearings Outer spherical ball bearing And eccentric sleeve overall dimensions

GB/T 307.3-2017 General Technology of Rolling Bearings rule^[7]

GB/T 307.2-2005 Rolling Bearing Measurement and Inspection Principles and Methods

GB/T 307.1-2017 Rolling Bearings Radial bearing common difference^[8]

GB/T 301-2015 Rolling Bearings Thrust ball bearing appearance size^[9]

GB/T 297-2015 Rolling Bearings - Tapered Roller Bearings - Boundary Dimensions inch^[10]

GB/T 296-2015 Rolling Bearings Double row angular contact ball bearing appearance size^[11]

GB/T 294-2015 Rolling Bearings Three Points and Four point contact ball bearing Profile ruler inch^[12]

GB/T 288-2013 Rolling Bearings - Self aligning Roller Bearings - Boundary Dimensions inch^[13]

GB/T 285-2013 Rolling Bearings Double row Cylindrical Roller Bearings Profile size^[6]

GB/T 281-2013 Rolling Bearings Self aligning ball bearing appearance size^[5]

GB/T 276-2013 Rolling Bearings Deep groove ball bearing appearance size^[4]

GB/T 275-2015 Rolling Bearings, Shaft and Housing coordination^[2]

GB/T 272-2017 Rolling Bearing Code method^[3]

GB/T 16643-1996 Rolling Bearings Needle Roller and Thrust Cylindrical Roller Combination Bearings Boundary Dimensions

GB/T 4605-2003 Rolling Bearing Thrust Needle roller and cage assembly And thrust washer

GB/T 5800-2003 Rolling Bearing Instrument Precision bearing

GB/T 4199-2003 Rolling Bearing Tolerance Definitions

GB/T 4662-2003 Rated Static Load of Rolling Bearings

GB/T 8597-2003 Anti rust Packaging of Rolling Bearings

GB/T 5868-2003 Mounting Dimensions of Rolling Bearings

GB/T 308-2002 Rolling Bearing Steel Balls

GB/T 307.4-2002 Rolling Bearings thrust bearing tolerance

GB/T 4661-2002 Rolling Bearings Cylindrical Rollers

GB/T 6930-2002 Rolling Bearings Vocabulary

GB/T 7217-2002 Rolling Bearings Flange Outer Race Radial Ball Bearings Flange Dimensions

GB/T 309-2000 Rolling Bearing Needle Roller

GB/T 274-2000 Maximum Chamfer Dimensions of Rolling Bearings

GB/T 273.3-1999 Rolling Bearings Radial bearing Overall dimension plan

GB/T 305-1998 Dimensions and Tolerances of Stop Groove and Stop Ring on Outer Ring of Rolling Bearings

GB/T 290-1998 Rolling Bearings Stamped outer ring needle bearing Overall dimension

GB/T 4459.7-1998 Mechanical Drawings - Representation of Rolling Bearings

Application in mill

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Mill hollow shaft The old method of installing rolling bearings is to process the hollow shaft into an inner diameter suitable for the bearing. The bearing thermal device, the bearing part, and the outer part of the bearing inner ring are provided with a top sleeve. The top sleeve is fixed on the hollow shaft with bolts by the feeding and discharging spiral cylinder (or the feeding and discharging bushing) for compression. During the operation of the mill, the feeding and discharging spiral cylinder and the fixing bolts are often loose, causing displacement of the top sleeve and the hollow shaft. Dust will enter the bearing box from the gap between the hollow shaft and the top sleeve, making the grease dirty, causing lubrication The bearing is often damaged due to poor performance.

In order to overcome the above shortcomings, after several years of practice and exploration, a new installation method was designed and has been well applied in some manufacturers.

The method is: Mill hollow shaft The diameter of the part where the rolling bearing is installed will be thickened, and the thin oil cooled by the hollow shaft will conduct the hollow shaft to the normal range where the temperature on the bearing drops below 60 degrees.

Assembly standard

1. First, select the rolling bearing with qualified quality, and then check the shaft diameter or bearing body matched with the bearing to determine the matching method. The main considerations include the working conditions, load, speed, temperature, etc. of the rolling bearing.

2. The end face marked with the model on the rolling bearing should be installed in the visible part, so that the bearing model can be easily identified when replacing the bearing.

3. The radius of the arc at the shaft diameter or shell hole shoulder shall be less than the radius of the arc of the bearing to ensure that the bearing is close to the shaft shoulder and shell hole shoulder after assembly.

4. The fixing device of rolling bearing must be intact and reliable, with proper fastening procedure and reliable locking.

5. During the assembly of rolling bearing, it shall be strictly kept clean to prevent sundries from entering the bearing.

6. After assembly, the rolling bearing shall be checked for flexible rotation and noise. Generally, the working temperature shall not exceed 50 ℃.

Assembly method

Rolling bearing

Before the assembly of rolling bearing, it is necessary to clean the rolling bearing to keep it clean and tidy; Then check the rolling bearing and assemble it according to its assembly requirements.

1. First, remove the residual grease and antirust oil from the rolling bearing.

2. First flush the rolling bearing with kerosene, then clean it with gasoline, and wipe it with clean cloth.

3. Other cleaning agents can also be used to clean the bearing and wipe it with a cloth.

4. Remember not to clean or dry the bearing with dirty oil or cloth or cotton yarn.

Assembly principle of rolling bearing: it shall be determined according to the bearing structure, size, working conditions and the matching nature of bearing components. The pressure during assembly shall be directly applied to the end face of the ring to be matched, and it is not allowed to transmit the pressure through the rolling element. Rolling bearing assembly generally includes press in assembly, temperature difference assembly and power frequency induction heater.

1. The rolling bearing should not be removed from the machine parts. If it must be removed, the correct tools and methods should be used.

2. Before assembling rolling bearings, appropriate cleaning agents and methods shall be selected according to the rust prevention method of rolling bearings.

3. Before assembly, the inner and outer micrometers shall be used to check the inner diameter of the bearing sleeve and the diameter of the journal. The fitting tolerance must meet the requirements of the drawing.

4. The rolling bearing is installed in the split bearing seat. There should be no gap between the joint surface of the bearing cover and the bearing seat, but a certain gap should be left between the outer ring of the bearing and the pad mouth on both sides of the bearing seat. The side clearance of the pad mouth can be measured and checked with a feeler gauge. If the clearance is too small or "collar clamping" occurs, it can be scraped with a scraper. In order to increase the clearance, it should comply with the table Clearance between Rolling Bearing and Split Bearing Seat.

5. Rolling bearing assembly includes drive in method, press in method and hot assembly method. When hammering with the driving method, red copper rod or sleeve shall be used as the tool to transmit the force, so that the force acting on the bearing is symmetrical. In the press in method, a press is used instead of hammering, and the casing is still used to transmit the force. It is strictly prohibited to use flame for direct heating during hot installation. 80~90 ℃ hot oil shall be used for heating. The oil temperature should not exceed 100 ℃. When heating the bearing, it shall not contact with the heating oil tank seat, and the bearing shall be hung in the middle of the oil layer to avoid annealing caused by local overheating.

The heating time shall not be less than 15min, and the inner sleeve shall be expanded to the required value before assembly. Do not pause during the hot installation process, and quickly install the bearing to the correct position at one time. If the steel ball cage in the bearing is oil resistant plastic, it should be heated with water, but the water should be wiped off in time after assembly.

6. The rolling bearing assembly shall meet the following requirements:

(1) The cleaned bearing shall be checked, and the bearing shall be free of damage and rust, and rotate flexibly without abnormal sound. The matching type and size of the bearing with the journal and bearing seat shall be checked, and the assembly can be carried out only after they meet the requirements;

⑵ During assembly, the pressure applied to the bearing shall be evenly distributed and perpendicular to the end face, and unilateral force shall not be prevented. Select the stress point according to the assembly relationship. If the bearing is assembled on the journal, the pressure should be applied to the inner ring of the bearing;

(3) During assembly, the bearing and shaft shoulder shall be close together, and the tapered roller bearing and radial thrust bearing The clearance with the shaft shoulder shall not be greater than 0.05mm, and other bearings shall not be greater than 0.1mm. The bearing cover and retaining ring must be flat and evenly close to the bearing end face, and the clearance shall be adjusted according to the technical documents;

⑷ During assembly, the end marked with specifications on the bearing shall be outward as far as possible to facilitate inspection and replacement. After assembly, turn it by hand to check whether there is jam, and then add proper grease. The sealing device must be assembled as required, and there shall be no oil leakage after sealing;

(5) The axial clearance of single row, double row and four row tapered roller bearings and radial thrust bearings shall be checked during assembly and adjusted according to bearing standards or technical documents;

(6) Various Radial bearing 、 needle bearing 、 Spiral roller bearing After assembly, it must rotate flexibly. After assembly of bearings with grease, clean grease with a volume of 65%~80% of the cavity shall be injected into the bearing cavity. For bearings lubricated with thin oil, grease shall not be injected.

(7) When assembling the bearing, the axial clearance and axial preload (axial pre interference) that should be adjusted should meet the requirements of the bearing standards or equipment technical documents.

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