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Nowadays, industrial technology is developing more and more rapidly, and various stainless steel materials are also being used in large quantities at this time. Industrial production cannot do without mechanical equipment, so many mechanical equipment cannot do without stainless steel bearings. Good stainless steel slewing ring bearings can be said to be an important guarantee for the production of mechanical equipment. Many friends are not particularly familiar with stainless steel slewing bearings. Next, the editor will talk about the characteristics of stainless steel slewing bearings for everyone to learn and understand.

1. The material of stainless steel slewing ring is special

Generally speaking, slewing bearings generally use two materials, 50Mn and 42CrMo, but stainless steel should be used for special purposes. The ferrules and rolling elements of stainless steel slewing bearings often use 9Cr18Mo, 9Cr18, 4Cr18 materials.

2. Excellent corrosion resistance

The sales volume of stainless steel bearings on the market is still considerable. You must know that stainless steel bearings have many advantages, so their durability is also very strong. First of all, good corrosion resistance is a major advantage of stainless steel bearings. Since this type of bearing has passed the extreme tests of high temperature and low temperature, it will have stronger corrosion resistance.

3. Washing resistance

Stainless steel bearings are also very resistant to washing. After we have used the bearings for a period of time, there is no problem in removing them for washing. Due to the water resistance of stainless steel bearings, rust will not appear even if they are washed in water.

4. Long service life

Because the material corresponding to the stainless steel bearing is the international standard stainless steel material, regular maintenance during daily use can extend its service life.

5. Wide range of use

Compared with slewing bearings of common materials, stainless steel slewing bearings have stronger rust and corrosion resistance, and are generally used in some special working conditions, such as underwater, wet seaside and other working conditions. Stainless steel slewing bearings are commonly used in food machinery, environmental protection equipment, medical equipment, and underwater operation tools.

The above is an introduction to the characteristics of stainless steel slewing bearings. Choose the appropriate dust cover and lubricant. Stainless steel slewing bearings can be used in an environment of -60℃~+300℃. Because of its high mechanical strength, large load capacity, and beautiful appearance, stainless steel slewing bearings are widely used in food processing, medical equipment, pharmaceutical machinery, nuclear industry projects and other equipment.

Luoyang Hengguan Bearing Technology Co., Ltd. mainly produces slewing bearings in the diameter range of 50-10000mm. Among them, stainless steel slewing bearings are a major characteristic product of Hengguan Bearings. At present, they have been equipped with stainless steel slewing bearings for many projects at home and abroad, and they are all very successful. Cases, well received and praised by customers.

With the increase of the operating time of the wind turbine, the sealing ring of the pitch bearing is gradually aging, the lubricating grease is gradually deteriorating, the waste grease is not drained smoothly and the pitch bearing is not completely rotated, resulting in uneven internal pressure, which will lead to the pitch bearing sealing ring. There are different degrees of grease leakage. If it is not handled in time, it may cause poor lubrication of the pitch bearing, thereby affecting the service life of the pitch bearing and the wind turbine. Today, the editor will conduct a detailed analysis of the causes of grease leakage in the pitch bearing of wind turbines for everyone to learn and understand.

 

The internal structure design of the pitch bearing is unreasonable

 

1, channel structure

 

The design of the pitch bearing channel affects the fluidity of the grease in the groove inside the bearing. Under normal circumstances, the variable pitch bearing is filled with grease from the grease hole. The pressure difference required to discharge the waste grease from the grease hole is less than the pressure value that the seal ring can withstand, and at the same time is greater than the resistance value of the grease flow, the seal ring No fat leakage. The required pressure difference is closely related to the resistance of the grease to flow. A small resistance requires a small pressure difference, and a large resistance requires a large pressure difference. If the design of the internal channel of the pitch bearing is unreasonable, the grease flow resistance will be large, which is not conducive to the uniform distribution of the grease and the internal pressure, and the grease cannot enter the grease discharge hole smoothly, resulting in poor grease discharge, resulting in grease at the seal ring overflow.

 

2, size and distribution of lipid pores

 

The grease injection holes and grease discharge holes of the variable pitch bearing should be distributed at reasonable intervals to ensure that the bearing can be smoothly injected with new grease and discharged. The distance between the adjacent grease injection hole and the grease discharge hole should be moderate. If the distance is too short, the pressure of the grease injection hole will be higher and the pressure of the grease discharge hole will be lower during grease filling, and the newly added grease will be easily discharged from the grease discharge hole; If the length is too long, the seal ring will bear greater local pressure when adding grease, which will easily lead to grease leakage. In addition, the cross-sectional diameter of the grease discharge hole is too small, the diameter of the grease collection bottle connected to the grease discharge hole is too small, and the distance between two adjacent rows of grease holes on the bearing is too large, which will also increase the resistance of grease discharge, resulting in poor grease discharge. Smooth, so that the internal pressure of the pitch bearing is too large, resulting in grease leakage.

 

Poor sealing

 

1. Aging and wear of the sealing ring

 

Most of the pitch bearings use nitrile rubber seals, which will age after long-term use. The aging rate is related to the acrylonitrile content in the nitrile rubber, the rubber content of the formula, the antioxidant and the use environment. In general, the nitrile rubber The service life of the sealing ring is 5~10 years. The pitch bearing adopts a contact seal. During operation, the seal ring contacts the friction surface of the seal. As the running time increases, the seal ring will gradually wear out, resulting in a decrease in sealing performance and insufficient pressure on the seal ring. Grease may be removed from the seal ring. Leakage.

 

2, the seal ring structure design is unreasonable

 

Pitch bearings generally use double-lip seals. The outer lip can block moisture, dust and other harmful substances from entering the inside of the bearing, and the inner lip can prevent grease leakage. If the seal ring structure design is unreasonable, the sealing effect will be affected after installation, and the seal ring may be deformed after the pitch bearing is operated, resulting in insufficient sealing ability or sealing failure, and the grease is easy to leak.

 

3. Improper installation and maintenance of the seal ring

 

Failure to install or maintain according to the process will result in uneven force on the seal ring. Poor interface bonding during the installation of the seal ring will cause the seal ring interface to break. After the subsequent pitch bearing grease injection operation, the seal ring is prone to bulging and warping (Figure 1 ) And the phenomenon of fracture, so that the grease will overflow from the gap, warpage and damage of the sealing ring.

 

4, the sealing ring is squeezed and damaged

 

When installing or maintaining the blades of wind turbines, hydraulic tensioners need to be used to apply torque to the connecting bolts between the blades and the pitch bearing. The distance between the connecting bolts and the sealing ring is relatively short, and the extension head of the hydraulic tensioner has a larger overall size. The stretching head is easy to press on the sealing ring to cause serious damage to the sealing ring, as shown in Figure 2. The subsequent operation of the pitch bearing may cause deformation and tearing of the sealing ring, resulting in a large amount of grease leakage.

 

Improper selection of grease or unreasonable setting of lubrication system

 

1. Improper selection of grease

 

The choice of grease usually refers to the actual working conditions of the pitch bearing, and also needs to consider the consistency of the grease and the type of additives. The consistency of the grease is closely related to the ambient temperature. Every time the ambient temperature drops by 5 ℃, the consistency will double and the fluidity of the grease will deteriorate. If the consistency of the grease is not appropriate or the pressure resistance is insufficient, subsequent use is likely to occur The solidification phenomenon blocks the grease system, causing the grease to not be discharged normally and leak from the sealing ring, as shown in Figure 3.

 

2. The amount of grease injection and the setting of the centralized lubrication system are

unreasonable

 

The pitch bearing needs to be filled with a certain amount of grease before operation. The filling amount is about 60% to 80% of the inner space of the pitch bearing. Generally, the filling amount is about 70%. There are also individual pitch bearing suppliers to ensure sufficient Choose 80% filling amount for lubrication.

 

Most wind turbines at home and abroad use centralized lubrication systems to fill the pitch bearing with grease. Some wind turbine manufacturers use manual and regular grease filling to further reduce the maintenance cost of the pitch bearing. Both of these two methods of refilling grease have shortcomings: the grease injection amount and grease injection period for manual regular grease injection are often empirical data, and there is a large deviation from the actual grease required for the pitch bearing. The grease injection volume is usually In this case, the lubrication time of the pitch bearing cannot be guaranteed. In addition, about 80% of the grease may be added to the pitch bearing before leaving the factory, which will easily cause a large amount of local grease to accumulate in the pitch bearing channel. ; The centralized lubrication system adopts automatic grease injection method to make the bearing lubrication more adequate. Although the lubrication time and grease injection uniformity of the variable pitch bearing are guaranteed, the centralized lubrication is performed when the variable pitch bearing is not running or the unit is shut down for a long time The system continues to inject grease according to its preset fixed program, which is also likely to cause a large amount of local grease accumulation in the pitch bearing channel.

 

Under normal conditions, the sealing pressure of the sealing ring of the pitch bearing is about 2.8×105 Pa. The grease injection pressure required when the pitch bearing is stationary and not working is about (2.5~2.8) x105 Pa. The grease injection pressure required when the pitch bearing is running is only It is about 0.6 x105 Pa. Due to the poor fluidity of the grease used in the pitch bearing, the large accumulation of grease caused by the above two kinds of grease injection methods will increase the pressure of the grease channel in the pitch bearing channel, thereby increasing the injection required during grease injection. Fat pressure. When the grease injection pressure is greater than the sealing pressure of the pitch bearing seal ring, the grease will leak from the pitch bearing seal ring under the action of the grease injection thrust.

 

In addition, if the air in the pressure pump or grease pipe of the centralized lubrication system is not completely emptied, the air will enter the pitch bearing channel along with the grease, resulting in excessive local pressure in the channel. When the pressure is greater than the pitch bearing The sealing pressure of the sealing ring will open the sealing ring, causing serious grease leakage.

 

3. Improper collection of waste fat

 

At present, the waste grease collection of pitch bearing of wind turbines generally adopts the method of installing grease collecting bottles in several waste grease discharge holes distributed on the circumference of the bearing. When new grease is added, the new grease squeezes the waste grease into the waste from the inner cavity of the bearing. Grease drains out of the small holes and drains into the fat collecting bottle, which needs to be cleaned regularly. In fact, as the running time of the pitch bearing increases, the waste grease collection effect is not good, and it is easy to leak grease.

 

The above is about the analysis and introduction of the reasons for the grease leakage of the pitch bearing of the wind turbine. As an important component of the wind turbine, the pitch bearing is used in a harsh environment, high maintenance costs, and complex forces, and directly affects the continuity of the entire pitch movement. Stability and accuracy. Therefore, in order to ensure the reliability of the life of the pitch bearing, the pitch bearing needs to be well sealed and lubricated to avoid grease leakage.

For bearing products, packaging is very important, not only to prevent rust, but also to protect the bearing from bumps during transportation and damage to the bearing. Bearing packaging is divided into inner packaging and outer packaging. So, what are the requirements for the packaging of bearings?

First, the inner packaging of the bearing

After the bearing is manufactured and passed the inspection, it will be cleaned and anti-rust treated, and then put into the inner packaging to achieve the purpose of waterproof, moisture-proof, dust-proof, shock-proof, maintain the quality and accuracy of the bearing, and facilitate the use and sale. .

1. The inner packaging of the bearing is divided into three categories according to the anti-rust period

① Short anti-rust period packaging

The anti-rust period is 3-6 months, which is suitable for bearings that are shipped to the same subscriber in large quantities and put into use in a short period of time. The two parties have agreed to use simple packaging based on the principle of ease of use.

② General anti-rust period packaging

The anti-rust period is one year, suitable for general-purpose bearings.

③ Long anti-rust period packaging

The anti-rust period is two years, suitable for special and precision bearings.

2, bearing inner packaging material requirements

There are polyethylene plastic tube (box), kraft paper, plain and wrinkled polyethylene composite paper, paper box, polyethylene or polyethylene plastic film, nylon fastening tape or plastic woven fastening tape, waterproof high-strength plastic tape, burlap bag, etc. . All of the above materials need to ensure that the corrosion resistance test of the material is qualified.

3, the requirements of bearing inner packaging method

①Miniature bearing

Every 10~15 sets of bearings are packed into a plastic tube, and every 5~10 plastic tubes are packed into a carton (or bag or roll pack).

②Medium and small bearings

Multiple sets of bearings are wrapped with polyethylene film, kraft paper or polyethylene composite paper for external use; multiple sets of bearings are packed into a plastic tube (box); single set of bearings is packed in polyethylene film bags, folded or sealed before repacking Into a paper box.

③Large bearing

Pack it in a single set of polyethylene film or polyethylene composite paper, and then put it into a carton; use a polyethylene film bag, pack the single set of folded bag openings, and then put it into a carton; put the single set into a special plastic box; Three-layer wrap-around packaging: polyethylene film tape or composite paper tape for the inner layer, fastening tape for the middle layer, and waterproof permeable plastic tape for the outer layer.

④Extra large bearing

Single set of three-layer wrapping packaging (same as above).

Single-by-four-layer wrapping package: After the above-mentioned three-layer wrapping package, the outer layer is wrapped with a layer of linen tape.

For separable tapered roller bearings with outer diameter ≥150mm, the inner and outer components should be lined with polyethylene film before packaging, or the inner and outer components should be packaged separately. For interchangeable cylindrical roller bearings with an outer diameter of ≥150mm, because the complete package is easy to be damaged, the inner and outer components can generally be packaged separately.

Secone. Standards for bearing outer packaging requirements

1. General materials and requirements for outer packaging of bearings

① Double corrugated boxes, the total weight (gross weight) of each box does not exceed 25kg, and the outside of the box is bound with plastic strapping.

② Nail board box (wooden box), the total weight of each box does not exceed 30kg, and the outside of the box is bound with blue steel tape.

③ Calcium plastic corrugated box, the total weight of each box does not exceed 25kg, and the box is bound with plastic strapping.

When packing bearing products with inner packaging into the box, plastic bags or plastic films should be lined in the box first; if there are gaps in the box, it should be filled with corrugated paper blocks, paper scraps and other dry materials.

2, pay special attention

It is especially important to emphasize that due to the heavy weight of large bearings, packing straps should be added to the packaging box to ensure the convenience of bearing handling and other processes. For the packaging of large bearings, each manufacturer has its own characteristics, such as the material requirements for the outer packaging, anti-counterfeiting marks, and so on.

Compared to other products, the packaging and transportation of bearings are very important. Whether it is a bearing manufacturer or a motor manufacturer, we are inseparable from the transportation link without exception. We must fully communicate with the transportation party and take necessary precautions.

Sometimes the technical indicators were normal when the rotation performance was tested in the factory, but the newly installed slewing bearing and slewing ring showed inflexible rotation. In addition, why the slewing bearing is not installed smoothly or even cannot rotate?

Reasons for the unsmooth installation of the slewing bearing

1, mounting hole. The threaded hole of the mounting hole is not standardized, the thread is not completely, and the thread is defective, which causes the bolt to be unable to be screwed in.

2. The center diameter and chord length of the mounting hole are out of tolerance too much, such as 3-5mm, causing the bolt to fail to perforate.

3, the positioning hole and the step size are out of tolerance and cannot be matched.

4. The bearing after heavy load has a dead center or ellipse in rotation, causing it to fail to operate normally.

5. The bearing is not in the installation direction of the installation design drawing, resulting in the opposite direction of the taper pin, which has potential safety hazards.

6. Interference of installation parts, such as tooth tip interference, there will be teeth gnawing phenomenon, and individual parts conflict with each other.

7. The negative clearance design is unreasonable, resulting in oblique force, unbalanced load and clearance after installation.

8. The equipment structure design is unreasonable, causing the debugging to not be carried out normally.

The slewing bearing may be difficult to rotate or unable to rotate

1. Idling of newly purchased products is not flexible

Please check the production date of the slewing bearing. If it takes a long time (such as more than half a year) and the climate is cold, it is possible that the salt mist and other temperament in the raceway will double the rotation resistance, which will make the slewing ring not work properly (cold areas, more prominent in winter) ) Elimination method: If it can run without other abnormalities, it can be used normally.

2, the operation after installation is not flexible

It may be that the surface of the main machine device and the surface of the slewing ring are not properly matched, resulting in that the axial clearance of the slewing ring behind the device cannot compensate for the deformation of the slewing ring. The slewing ring is in a state of negative clearance, and the rolling elements are difficult to run in the raceway (sometimes with abnormalities). Noise) or poor meshing of the large and small gears; or foreign matter stuck in the large and small gears. Elimination method: re-process the plane of the main machine device to make the device plane meet the requirements; re-adjust the gear meshing backlash according to the requirements, especially pay attention to the gear jump position; check to ensure that there is no foreign matter in the meshing position of the large and small gears; exchange a slewing bearing with a larger gap .

3, the operation is not flexible during use

The sealing strip is damaged, causing foreign matter to enter the raceway (such as poor working conditions, dust immersed in the raceway, etc.), and the isolation block is deformed and difficult to operate; there are hard objects or other conditions at the meshing of the large and small gears, such as broken teeth.

The above is an analysis of the annoying reasons why the slewing bearing is not installed smoothly or even cannot rotate. I hope everyone will be helpful after reading it. When testing the rotation performance of the new bearing, it can rotate lightly, but at this time, it does not represent a reasonable index. The contact point, contact angle, and relative position of the connecting point of the channel are in line, and whether the two circles are close to the perfect circle. The two circles are completely or close to positive balance. In layman’s terms, just like the two rails of a train, they should be close to theoretical parallel, high and low parallel, so that the train will be stable, high-speed, orderly and safe. Therefore, to test the rotation performance, the loading experiment is a very important basis and effective means.

Slewing bearing is one of the important parts of many modern machinery and equipment. It is called “joint of machine”. Many people are familiar with various parameters of slewing bearing, including clearance, inner and outer diameter, friction coefficient, etc. Many of my friends don’t know the module of supporting gear, so let’s follow the editor today to understand it.

 

1. what is the slewing ring gear module

 

The length of the arc (gear)/straight line (rack) occupied by a single gear tooth in the indexing circle (gear)/or line (rack), its length is π * m, and m is the modulus.

 

What does the module of the slewing ring represent: The module of the slewing ring represents the product of the tooth pitch and the number of teeth of the slewing ring gear, which is the circumference of the index circle. The gear modulus of the slewing ring determines the size of the tooth. The gear modulus is a basic parameter for the calculation of the gear size. The symbol is “m”. Gear cutters can be standardized, so that the standard modulus of gears can be standardized for mass production. Facilitate the replacement of later accessories. In the same way, “modulus” refers to the ratio of the pitch t between the tooth profiles of two adjacent gear teeth on the same side and the circumference ratio π (m=t/π), in millimeters.

 

If the number of teeth of the slewing ring gear is constant, the larger the gear modulus, the larger the radial dimension of the gear. The teeth of a gear with a large modulus are thick, and for two gears with the same number of teeth, the outer circle of the gear with a large modulus is larger. Therefore, the modulus of the gear in a watch is very small, and the modulus of the flywheel and transmission gear on the mechanical punching machine is large. The modulus of the two meshing gears must be the same. Modulus is the basic parameter of gear design, and it is used in many calculations of gear design.

 

 

2. Reasonable selection of gear modulus

 

When designing a gear, one of the important parameters is this modulus. The gnawing of the gear will produce gnawing pulsation. The main reason is that it has a great relationship with the elastic deformation of the gear teeth. It is a basic part of the gear design. Parameter-gear modulus, if it is a relatively large modulus (that is, a gear with a relatively large size), it will also have a relatively large load-bearing capacity. The modulus parameter is inversely proportional to the degree of bending of the gear teeth. The increase of the modulus means that the rigidity of the gear teeth is improved, so that the elastic deformation of the gear teeth will not be great when the gnawing transmission is carried out, which greatly reduces the impact force formed by the gear teeth, thereby achieving The purpose is always greatly reduced. Therefore, from this point of view, the modulus should be increased appropriately, but the error generated when machining gears is also related to the modulus. If the modulus is increased, the tooth profile and pitch will also be increased. At this time, the error of gnawing noise will also increase accordingly, so the choice of modulus should be determined according to the specific situation.

 

In the case of keeping the modulus unchanged, the diameter of the gear is proportional to the number of teeth, so the change of the number of teeth will also change the bending amount and elastic stiffness of the gear teeth: the strength of the noise generated by the sound source is not only related to the energy of the vibration source It is related to the size of the radiation area. If the radiation area is increased, the radiation power will also increase. Increasing the diameter of the gear will increase the noise radiation area, which will greatly affect the gear. Effective noise control. Therefore, in the relevant design, within the permissible range of ensuring the strength of the gear, the number of teeth and the small modulus should be used as much as possible, and the reasonable selection of materials and heat treatment methods can be combined to promote the improvement of the strength of the gear teeth, thereby Reduce the gear tooth diameter to achieve the purpose of reducing gear noise.

 

The above is the relevant introduction about the slewing ring gear module. In the slewing ring selection process, the first two sets of data listed in the national standard parameters of the slewing ring module should be selected first, which is more important for the adaptation of the bearing and the replacement of accessories. Convenient, but non-standard gears with customized bearing module requirements for bearings used in special machines are not within the above constraints.