Slewing bearing is a kind of large bearing often used in modern machinery and equipment, which can bear large axial, radial and overturning moments at the same time. At the same time, it is also an important component in the rotary system of large-scale amusement facilities, which bears various loads during the operation of the equipment.
In addition to calculation and selection, attention must also be paid to its correct installation slewing bearing and use.
The harm caused by installation errors and improper use to amusement facilities cannot be ignored. So how to install the slewing bearing of amusement facilities? The following editor will introduce to you the installation method of the slewing bearing of large amusement facilities. The motion forms of amusement facilities mainly include rotary motion, linear motion and compound motion of rotary and linear motion. Among them, rotary motion is the main motion form of amusement equipment, such as carousel, automatic control plane and high-altitude flying, etc. The main component to realize rotary motion is slewing bearing.
1.Installation form of slewing bearing of amusement facilities
In the field of amusement equipment, there are two types of installation methods for slewing bearings: horizontal installation and vertical installation of slewing bearing. The operating characteristics of flying towers and self-controlled aircraft amusement facilities are that they rotate around the central axis.
Flying tower-type amusement facilities include high-altitude flying, shaking head flying chair, etc., and self-control aircraft amusement facilities include self-control plane, big octopus, etc. The installation form of the slewing bearing in this type of equipment is horizontal installation. Sightseeing car amusement facilities are characterized by rotating or swinging around the horizontal axis. Sightseeing car amusement facilities include wild shouts, large pendulums, etc. The installation form of the slewing bearing in this type of equipment is vertical installation.
2.Installation of slewing bearing
1. Before installing the slewing bearing, check the mating surface and clean the two installation surfaces to avoid any solvent from contacting the sealing belt or entering the raceway. Do not paint the sealing belt. 2. The parts of the slewing bearing mounting seat should have sufficient rigidity, the contact surface of the bearing must be cleaned, there should be no lubricating oil and must be kept dry,
and the mating surface should be machined to ensure that the two mating surfaces and the two ends of the slewing bearing are in the entire Complete contact on the circumference to meet the flatness and inclination required by the relevant standards. 3. The bolts selected for the slewing bearing are high-strength bolts, and the length of the installation bolts shall not be less than 5d (d is the thread diameter). 4. For the connection of the slewing bearing of the amusement equipment, high-strength bolts above 8.8 are used, and full-threaded bolts cannot be used. The anti-loosening method is the double-nut method.
The two nuts should be the same. It is not high to cause extrusion plastic deformation, which is conducive to maintaining the reliability of preload.
Since the spring washer will destroy the centrality of the bolt’s force, reduce the pressure area and rigidity of the nut on the connecting parts when passing through, and reduce the connection strength of the bolt. Under any circumstances, spring washers should not be used. 5. When installing slewing bearing, firstly position the slewing bearing radially, and then tighten the installation bolts crosswise, that is, use star-shaped installation, and carry out symmetrically and continuously in the 180° direction, and then re-tighten it again to ensure that the bolts on the circumference have the same pre-tightening.
force, and check the rotation of the turntable slewing bearing. In order to increase the reliability of the connection, the prestress of the tightened bolt should be 70% of the yield strength of the bolt material. 6. In order to ensure the stable rotation of the turntable installation of slewing bearing , the gears should be checked before the installation bolts are fully tightened. The minimum value of the tooth side clearance is generally 0.03 ~ 0.04 X m (module). , recheck the gear tooth clearance of the pinion on the entire circumference. The above is the explanation of the installation method of slewing bearings for large amusement facilities.
Luoyang LYMC Bearing is a comprehensive entity enterprise integrating design, research and development, production, sales and service. Products are widely used in new energy, medical, amusement, automation, lifting, construction, mining, metallurgy, ports, textiles, ships, environmental protection, aerospace, wind power and other fields. In addition, it also implements personalized optimized design and customized flexible production for different customers to meet customer needs.
The raceway of the slewing bearing generally needs to be heat treated. In the heat treatment process, because the diameter of the raceway circle of the slewing bearing is relatively large, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece to be hardened and then add water to cool it. , this process is completed continuously.
1.How is the slewing bearing soft belt produced?
During the production and processing of the slewing bearing, the raceway of the device generally needs to be heat treated. The usual processes are: forging → rough machining → quenching and tempering treatment → finishing → raceway surface flame surface quenching → raceway surface grinding and other processes . One of the raceway surfaces is flame quenched to form a soft band. The so-called slewing bearing soft belt is the area that has not been heat treated. The formation of the soft band is necessary for the heat treatment process. In the heat treatment process of the slewing bearing soft belt,because the diameter of the raceway circle of the slewing bearing is relatively large, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece to be hardened and then add water to cool it.
The heating flame spray gun and the water gun are installed together and make a circular motion along the circle of the workpiece. When the movement is close to 360 degrees, the heating and water spray are stopped immediately. That is, the circular areas of heating and water spray do not overlap.
Cracks in the workpiece can occur if the circle areas where the heating and water spray occur overlap (heat treatment at an angle greater than 360 degrees on the circle). The tangential width of the unheated area is typically 15 mm. This 15 mm area is called the soft belt in the slewing bearing, that is, the so-called soft belt is the area without heat treatment. The formation of the soft band is essential to the heat treatment process. Under normal circumstances, the steel character “S” is marked on the position where the soft belt exists in the workpiece to indicate the specific slewing bearing soft belt position. The installation position of the soft belt is essentially to improve the life of the bearing.
From the perspective of the user and the manufacturer, it is still a reasonable position to install the upper and lower ring soft belts of the slewing bearing. Therefore, the manufacturer of the slewing bearing should accurately mark the position of the soft belt of the slewing bearing, and the manufacturer and installer should reasonably install the position of the soft belt of the slewing bearing as needed.
Second,the installation position of the slewing bearing soft belt
Usually the upper loop flexible belt of the slewing device is installed at a position perpendicular to the projection line of the pitching rotation plane. For example, the upper loop flexible belt of the slewing device of a ship loader or stacker-reclaimer should be installed at a position perpendicular to the center line of the cantilever and cut through the center of rotation , that is, standing at a 90-degree position facing the left or right side of the cantilever on the center of rotation. In the usual mechanical design, the soft belt does not have the stress state of the support roller of the slewing bearing device at this position.
The installation position of the lower ring soft belt of the slewing device should be determined according to the center of gravity of the equipment and the range of the slewing angle. If the rotation angle is 100 degrees left and right, and the center of gravity of the upper part of the rotation is in the front, it is recommended to install the lower ring soft belt at the rear, that is, at a position of 180 degrees. If the change position of the center of gravity of the upper part of the rotation is the same in the front and rear positions, the angular position of the lower ring soft belt can be installed arbitrarily. Because of the inevitability of the soft belt on the slewing bearing device, it is required that the user who uses and selects the slewing bearing device should install the position of the soft belt reasonably to improve the service life of the bearing. The general principle is to try to install the soft belt in a position where the soft belt is under less pressure during the load change.
1.Common troubleshooting methods for excavator slewing bearings
First, the rotation of the excavator slewing bearing is not flexible (1) After installation, the operation is not flexible, and the excavator slewing bearing installation surface is not well matched. The large and small gears are poorly meshed. If there are foreign objects stuck in the large and small gears, remove the foreign objects on the installation surface, use shims to level them, and re-adjust the meshing backlash of the large and small gears as required. Pay particular attention to the position of maximum gear runout. Check to make sure that there are no foreign objects in the meshing position of the large and small gears. (2) The operation is not flexible during use. Lack of grease, top up as required. The sealing strip is damaged, causing foreign objects to enter and roll in (such as poor operating conditions, intrusion of dust, etc.); check the meshing of the large and small gears for foreign objects or broken teeth. Second, the abnormal sound
(1) After assembly, there is abnormal noise during trial operation. The treatment method is the same as “inflexible operation after installation”, or the large and small gears are not meshed enough, sometimes tight and sometimes loose, and the meshing at the maximum position of the tooth jump is too tight to produce abnormal noise. (2) Abnormal noise occurs during use. There is a lack of grease in the raceway, and foreign objects, such as sand, iron filings, etc., are mixed in the pipe. Pay attention to whether the sealing strip is damaged and whether the mounting bolts are loose. Three, shake (1) The mounting bolts are loose, causing shaking during work. Immediately check all inner and outer ring mounting bolts and tighten as required. (2) Check whether the overload operation is performed and operate in strict accordance with the regulations. (3) Long-term overload operation leads to crushing of the raceway and excessive clearance. Fourth, broken teeth (1) Broken teeth are often directly related to installation. The gap between the large and small gears is not properly adjusted during installation. If the requirements are not met, the teeth are broken due to poor meshing of the two teeth during operation, and the gap should be adjusted according to the requirements; the meshing gap adjustment with the pinion at the maximum position of the tooth skipping is not carried out as required, resulting in the pinion meshing with the large gear at the maximum position of the tooth skipping during operation. If it is stuck and causes broken teeth, the green paint position should be adjusted to mesh with the pinion on the way, and the test run should be carried out after adjustment according to the requirements; the first line of the large and small gear shafts is not parallel, and the large and small gears are poorly meshed after installation, resulting in broken teeth, which should be guaranteed. The meshing of the two gears is parallel; the mounting bolts of the slewing bearing are not tightly fixed, and the large and small gears are poorly meshed, resulting in broken teeth, and the bolts should be tightened as required. (2) Use aspects. Violating the operating rules, overloading and rotating at high speed, the host collides (sweeps) obstacles, etc. It should be operated in strict accordance with the requirements of the operating procedures. When the slewing bearing meshes with the pinion, there is a foreign object stuck, and the large and small gears should be kept clean and checked frequently.
2.Reasons and solutions for inflexible operation of excavator slewing bearing
The excavator slewing bearing is an indispensable part of the excavator slewing device. Whether the excavator can turn left or right during work is inseparable from the credit of the slewing bearing. The slewing bearing is mainly used to support the quality of the upper body and bear the working load. Due to the heavy load operation of time and the influence of the environment, the phenomenon of inflexible operation will appear after a long time, which will cause a lot of trouble when we use it, and there is no way to work well.
The reason why the excavator slewing bearing is inflexible
Reason 1: The slewing bearing gear is deformed or broken, causing jamming or inflexible movement. Solution: Repair the gear and re-weld the gear. Reason 2: There is a problem with the sealing system of the slewing bearing, which will enter the sundries, such as stones, sand, etc., resulting in stuck or insensitive movement. Solution: Clean up all the debris. Reason 3: The newly purchased product is inflexible in idling. Check the production date of the slewing bearing. If the time is long and the climate is cold, it is possible that salt mist is mixed in the raceway, which will cause the rotation resistance to multiply and make the slewing bearing run poorly. Remedy: After afterburning, if it can run and there is no other abnormality, it can be used normally.
Reason four: overload operation, resulting in inflexible movement of the slewing bearing. Corresponding solution: The workload needs to be reduced. Reason five: The position of the excavator slewing bearing is not flat. Solution: You need to change the position of the platform and work in a flat position. Reason 6: There is a lack of lubricating oil in the excavator slewing bearing. The grease causes the friction to increase and the resistance to increase, which will cause the movement to be insensitive. Solution: add lubricating oil of the same specification or replace all lubricating oil. Reason 7: The operation of the excavator slewing bearing is not flexible. It may be that the installation surface of the main engine and the excavator slewing bearing installation surface do not cooperate well, resulting in the axial clearance of the slewing bearing after installation cannot compensate for the deformation of the excavator slewing bearing. Difficulty running in the raceway may sometimes be accompanied by abnormal noise, poor meshing of the large and small gears, or foreign objects stuck in the large and small gears. Solution: ①Re-process the installation plane of the host to make the installation plane meet the requirements; or use the gasket filling method to deal with it. ②Re-adjust the meshing backlash of the large and small gears according to the requirements, especially pay attention to the position of the gear beating. ③ Check to ensure that there is no foreign matter in the meshing position of the large and small gears. ④ Replace a slewing bearing with a slightly larger clearance. Reason 8: The sealing strip is damaged, causing foreign objects to enter the raceway, such as poor working conditions, and dust intrusion into the raceway. Solution: Replace the sealing strip.
The following items are the possibility of the slewing ring/slewing bearing being difficult to rotate or unable to rotate:
 The idling of newly purchased products is not flexible. Please check the production date of the slewing bearing. If the weather is cold for a long time (such as more than half a year), it is possible that the temperament such as salt mist is mixed into the raceway, which will cause the rotation resistance to multiply and make the slewing bearing not work well (cold areas, winter is more prominent ) Remedy: If it can run after afterburning and there is no other abnormality, it can be used normally.
 After the installation, the operation is not flexible. It may be that the surface of the host machine and the surface of the slewing bearing are not well matched, so that the axial clearance of the slewing bearing after the installation cannot compensate for the deformation of the slewing bearing.
The slewing bearing is in a state of negative clearance, and the rolling elements are rolling Difficulty running in the channel (sometimes accompanied by abnormal noise) or poor meshing of the large and small gears; or foreign objects stuck in the large and small gears.
Remedy: Re-process the plane of the host device to make the device plane meet the requirements; re-adjust the meshing backlash of the large and small gears according to the requirements, especially pay attention to the maximum position of the gear runout; check to ensure that there is no foreign matter in the meshing position of the large and small gears; replace a rotary with a slightly larger clearance support.
 The operation is not flexible during use. The sealing strip is damaged, causing foreign objects to enter the raceway (such as poor operating conditions, immersion of dust in the raceway, etc.) the deformation of the isolation block leads to difficulty in operation; there are hard objects or other conditions at the meshing of the big and small gears, such as broken teeth.
Inspection and Acceptance of Slewing Bearings Key Technical Parameters
This article discusses how to diagnose, test and accept slewing bearings after understanding more professional knowledge? What are the main factors for reference, so that the outline can be drawn. The slewing bearing plays the role of bearing, connecting and rotating in the equipment. The important thing in the mechanical equipment is the link device, which must have the ability to support and bear, so it is very important to choose the appropriate standard slewing bearing.
In short, whether it is diagnosing faults, detecting or accepting slewing bearings at the factory, the following technical parameters are verified or required inspection items.
1 The overall dimensions of the slewing bearing, especially if it involves positioning, such as step dimensions;
2 The size of the device hole, the core size in the slewing bearing, the size, number, distribution position of the device hole, wire hole, blind hole, counterbore, thread thickness.
3 Gear parameters, modulus of teeth, coefficient of modification, common normal, tooth surface roughness, commonly known as gear grade
4 Bearing clearance and runout
5 Lubrication system and seals
6 The material, heat treatment, flaw detection and inspection report of the slewing bearing.
Next, you need to understand the topics discussed in depth in this article, as follows:
1. The slewing bearing accepts three forces, namely axial force, radial force and overturning moment. The influence of the thrust of the slewing bearing of the vertical device is relatively large, such as the TBM shield machine, etc., and there is also one that has the largest overturning moment.
2. The diameter of the center circle of the rolling element and the diameter of the rolling element are two important parameters that affect the load distribution of slewing bearings and slewing bearings. Generally, the larger the diameter of the center circle of the rolling element of the bearing, the more uniform the load distribution and the greater the bearing capacity.
The diameter of the rolling element is within a certain range, and the larger the diameter, the greater the bearing capacity. Based on the Hertz elastic contact theory, the static equilibrium equation of the four-point contact ball slewing bearing is established, and the Newton-Raphson method is used to solve it numerically.
Taking a typical type of slewing bearing as an example, the load distribution of multiple sets of bearings is numerically simulated, and the influence of the diameter of the rolling element and the diameter of the center circle of the rolling element on the bearing load distribution is analyzed and studied, which provides a reliable theoretical basis for the shape design of the slewing bearing. .
3. Lubrication system, slewing bearing (slewing bearing) mostly use 2# base pressure lithium grease. Lithium-based grease and base-pressure lithium-based grease are divided into: No. 1, No. 2#3, which have good water resistance, rust prevention, oxidation resistance and lubricating properties, excellent high and low temperature performance and mechanical stability , a multi-action short-lived grease. Its quality index specification is GB7324-94, but it is not suitable to use different grades of grease.
The operating temperature range of No. 1-3 grease: -20℃—120℃. Precautions for use: 1 Avoid mixing with water and impurities during storage and transportation. 2 Do not mix with other greases. 3 Do not use after heating. 4. After use, the remaining grease should be smoothed in the original packaging to prevent oil separation.
How to analyze the quality of lubricating grease:
1. Lighting method 2. Oil drop trace method 3. Oil flow observation method 4. Hand twisting method ; It is a good lubricating oil if it is twisted on the hand and feels no impurities, and it is transparent, clear and free of impurities under the sun; it feels smooth and yellow in color when it is touched by the hand.
4. Bearing clearance, slewing bearing, and slewing bearing clearance are divided into axial clearance and radial clearance according to the different measurement directions. Radial clearance is the basis for the assembly of the inner group, outer ring and rolling elements of the bearing.
It is an important technical quality requirement item in national regulations and other regulations, and is also an important inspection item. From the perspective of bearing application, clearance is also one of the important technical indicators. Whether the bearing can obtain satisfactory performance depends largely on its radial clearance. From the design and use of bearings, the clearance can be divided into: design clearance, original clearance, device clearance and operating clearance.
The clearance achieved after the bearing is assembled is the original clearance, and the clearance changes after the main engine is installed, which is called the installation clearance (or fitting clearance), and the clearance of the bearing during the actual operation is called the working clearance.
When the bearing is working, the temperature rise will change the temperature difference between the internal and external factors, which will reduce the clearance of the device. At the same time, the load will cause elastic deformation of the rolling element and the ring, which will increase the clearance. In the case of a ship, the working clearance is slightly larger than the device clearance. In order to obtain the most satisfactory working performance, an appropriate working clearance should be selected.
5. Speed limit, 1. The running form of the slewing bearing rolling element relative to the raceway wall, sliding along with the rolling, compared with other rolling bearings, the slewing bearing sliding is more serious. Therefore, the slewing bearing is not suitable for high-speed places.
Second, the slewing bearing is a heavy-duty bearing, running at high speed, and the centrifugal force generated by dozens of tons of heavy objects at high speed is huge. Such equipment is classified as high risk.
3. Most of the equipment used in the slewing bearing is heavy-duty lifting and transferring equipment. Therefore, this equipment itself does not need high-speed rotation work.
6. Install bolts and flat washers. The bolts are above grade 8.8, the gaskets are modulated washers, and spring washers are disabled. First of all, when the slewing bearing is connected by bolts and nuts, the bolts are required to be high-strength bolts (grade 10.9).
Secondly, the contact area of the spring washer is not as large as that of the flat washer, and the place with large pre-tightening force is not as reliable as the flat washer. The larger pre-tightening force of the bolt (such as the pre-tightening of bolts of grade 8.8 and above) may cause the spring washer The plastic deformation of the adjacent support surface, in the future use, the preload may appear “relaxation” as the deformation increases.
For slewing machinery, the vibration and overturning moment during operation will be relatively large. If the opening of the spring washer is added, the intensity of the vibration will be aggravated and the slewing bearing ring will be deformed.
In addition, a suitable flat washer can increase the support area, and can prevent the extrusion plastic deformation of the workpiece with insufficient hardness when the bolt is pre-tightened to a certain level, which is conducive to maintaining the reliability of the pre-tightening.
Therefore, slewing bearing requirements prohibit the use of open washers such as elastic washers and the like.
7. The groove pattern and waviness of the slewing bearing are caused by vibration during the grinding process. The greater the vibration during the grinding process, the greater the amplitude. As the amplitude increases, the waviness value of the waviness also increases. The waviness is generally detected with a roundness meter. Roundness measurements show profiles in the spectrum, higher than
The peak-to-valley amplitude of a set of wave numbers within a range of roundness wave numbers is the waviness. Waveforms of 2-15 waves are generally called roundness, and waves of 16-500 are generally called waviness! Slewing bearing waviness generally refers to the microscopic condition of the raceway and rolling element surface. Most of the waviness can be repaired in the ultra-finishing process, while the roundness can only be repaired about 40% or less.
8. The rotation of the slewing bearing, the slewing bearing and the ordinary bearing are very different in the rotational flexibility. The slewing ring/slewing ring bearing is a heavy-duty, low-speed, extra-large bearing, and the initial torque is much larger than that of ordinary bearings.
In addition, the sealing belt and the pressing friction resistance of the inner and outer rings are doubled. The grease filled in the temporarily placed slewing bearing raceway volatilizes and corrodes by air. For these reasons, the frictional resistance of the slewing bearing increases, making it difficult to rotate. However, this requires normal phenomena. After forcibly using the lubricating oil for a day or two, the operation will gradually become more flexible.
1. Before mounting, remove all paint, grease and other foreign substances of both the structures and bearing and check that the finish and flatness of the mounting surfaces are acceptable.
Theallowable surface finish is 125 rms maximum and the flatness must not exceed the following in any 180° section: .005″ (.13mm) for bearings up to 20 inch (50.8 cm) diameter, .006″ (.15 mm) to 40 inch (101.6 cm) diameter and .007″ (.18 mm) up to 60 inch (152.4 cm) diameter. The maximum out-of-flatness must not occur more than once in any 180° section.
2. The slewing bearing support structures must be sufficiently rigid and free of distortion during operation to avoid uneven or localized loading on the bearing or the fasteners.
3. The non-heat treated zone (soft spot) on the bearing rings are identified by a filler plug on one ring and typically the letter ‘G’ stamped on the other ring. The slewing rings shall be mounted such that the soft spots are located in the application’s most lightly loaded region.
4. The high point of the gear teeth, where the runout is a maximum, is typically identified with blue paint. This is the point where the backlash shall be set to the mating gear as follows: .006/.009″ (.15/.23 mm) for 5/7 pitch, .007/.011″ (.18/.28 mm) for 4/5 pitch, .008/.013″ (.2/.33 mm) for 3.5 pitch, .009/.014″ (.23/.36 mm) for 3 pitch, .011/.016″ (.28/.41 mm) for 2.5 pitch and .013/.018″ (.33/.46 mm) for 2 pitch.
5. Fastener design and performance is not the responsibility of LYMC. However, the LYMC rating of the bearing assumes that the fasteners shall be grade 8 (w/ 120 ksi proof strength) or better and shall be used with flat, hardened washers.
Fasteners shall be preloaded to 70% of the proof strength and periodically checked to be sure that this preload is maintained while in service. All fasteners must be accessible. Do not use a thread locker such as Loctite.
6. Welding on or near the slewing ring bearing is not permitted.
7. Although grease is typically installed at the factory, the bearing raceway must be lubricated before operation with an acid-free, non-resinous, water repellant, non-aging, extreme pressure grease recommended for bearings.
Relubrication will be needed daily to monthly, depending on the severity of the application. Pump the grease while slowly rotating the bearing until the grease appears around the seal lips. Do not wipe away the ejected grease.
8. If the slewing bearing has gear teeth, the gear teeth will require a different grease than the bearing raceway. Gear teeth are shipped from the factory dry.
LYMC recommends greases with a high lithiumcontent and which are also recommended for exposed gear teeth by the lubricant manufacturer. Be sure to not mix greases as the grease used on the gear teeth must not be used in the bearing raceway. Relubricate the gear teeth when relubricating the raceway.
2.How does the turntable bearing keeper structure and form affect rotational performance and reliability indicators?
Generally, the overall retention frame is the best, the box holder is again, the isolation block is most conservative, reducing friction, increase flexibility.
Copper cage, better than aluminum holders, second nylon segmented cage, polytetrafluoroethylene maintained the most economical.
During the design selection process, the working conditions must be complied with the technical route, which will also determine the form of the cage.
3.Nylon Cage Effect of Slewing Bearing
The role of the holder is equivalent to the bones of the turntable bearing, while different materials, different structural cage, adapting to different working conditions, load, speed, installation methods and stress to the turntable bearings are particularly large. This paper introduces the effects of PTFE nylon retention holder steel retention frame copper retention frame on turntable bearings.
The nylon retention is a commonly used retaining frame, high toughness, oil-resistant corrosion-resistant resistance to a high and low temperature, -40 / + 60, beautiful, isolation block, box holder, basically satisfied with most of the conditions.
The segmented polytetrafluoroethylene holder, a good flexibility function, which is fully utilized at the four-point ball bearings, reducing friction, improving the rotation performance, is commonly used under high speed rotation, vertical mounting, tilt force.
Steel cage and copper retention frame, with respect to high temperature, dust, and high speed, adoption, cost is relatively high.
4.How does a slew ring work and what are its component parts?
Two concentric rings make up the main structure of a slewing bearing. The outer ring usually lies flat against a motionless surface and is screwed into place via evenly spaced mounting holes. The inner ring is usually affixed to a turning object via an adapter plate or bracket. It usually moves in a rotational manner while the outer ring stays affixed to the mounting surface.
Relative rotation between rings is facilitated either by rolling or sliding elements. For slewing bearing that operate with ball bearings, parts that facilitate greasing of the system are included, such as seals, load plugs, grease fittings and taper pins. For slewing rings that are based on sliding elements, replaceable plastic liners lie between the inner and outer rings.
Because slewing beaerings based on ball bearings have very small contact points (ball bearings touching the inner and outer ring surfaces), they are able to move with very low friction.
Slewing rings that are based on plastic liners to facilitate movement (with a larger inner ring surface to better handle heavier loads) work better for flat, horizontal applications . Vertical applications are better suited for ball bearing-based slewing rings.
Both slewing ring types can include gears on the outer ring OD or the inner ring ID to facilitate different application requirements.
The different ways to drive a slewing ring include:
One distinct advantage of a slewing bearing using plastic liners is that it is electrically insulating. That is, cables can run through the center of the slewing without requiring any additional layer of polymer or any other form of grounding. Slewing bearings based on ball bearings, in contrast, require an additional layer of polymer or some form of grounding in order to prevent electricity from traveling through the slewing ring from the cables.
1.Reasons and solutions for the inflexible rotation and sound vibration of the slewing ring bearing:
Since the general large slewing ring bearing installation equipment and site do not have the ability to deal with complex faults, once the large bearing is not smooth, inflexible, or even has a dead point in a certain area, it is usually at a loss, and there are other large bearings. When the bearing rotates, it is accompanied by sharp noises and even swings and vibrates, which makes the equipment manager or operator panic all day long.
Generally speaking, as long as the large bearing can operate normally, a little noise and vibration are not enough to affect safe production, but it must be time to replace the large bearing, because at this time there must be losses inside the large bearing, either rolling elements or The cage, and the most likely is the fatigue shedding of the raceway hardness layer.
The second is that the eccentric load can be changed at the equipment site. For example, adjust the eccentric load on site, such as bucket turbine bearings, stacker-reclaimer bearings and ladle large bearings. Generally, it is equipped with eccentric load, and adjusting the eccentric load is the most reliable and safest method. Then quickly confirm the drawings and prepare for the production of new bearings.
The third is to fully add grease. It is necessary to fully understand that you must try to add grease. If necessary, even if the outer sealing strip is removed, clean it with kerosene from the surrounding direction and then add thin grease. You must know that only grease lubricated inside will minimize the internal frictional resistance.
Fourth, the obstacles that interfere with the operation of the large slewing ring bearing must be removed, such as the falling protective cover, the dust baffle, and the foreign matter interfering with the rotation of the gear. Often the noise of the large bearing comes from outside interference to a large extent.
Fifth, the new bearing is stuck or unable to rotate after installation, mostly because the contact point of the bearing channel is not good, the rotation is elliptical or the rolling element tolerance is inconsistent, which causes the rotation to be blocked. A factory reset should be initiated immediately.
2.How to deal with the abnormal sound after the new slewing bearing is installed?
Under normal circumstances, the slewing ring bearing has undergone a rotation test before leaving the factory. After installation, there is no external interference. If the new bearing is installed with abnormal noise, it can be handled and eliminated in the following ways.
1. Refill the thin grease from the lubricating hole and add it from the symmetrical grease nipple. During the filling process, rotate the bearing and rotate it from the positive and negative directions for several weeks.
2. Rotate the bearing to 360 degrees before trying to get the grease out of the seal or the oil discharge hole.
3. If there is no accident, the abnormal sound of the new bearing will disappear within one month to three months.
4. If it is a negative clearance bearing or a zero clearance bearing, check the rotation accuracy again.
5. For the three-row ball bearing and the cross-roller structure bearing, if the grease is fully filled, the abnormal noise will disappear quickly.
6. Especially for large bearings, installation and debugging, the levelness of the base, and the eccentric load will affect the bearing more or less, and should be carefully adjusted.
3.Regarding the influence of clearance on the rotation accuracy and life of the slewing bearing, this paper takes the four-point contact ball bearing as an example, from the core index of the influence of the clearance value on the slewing bearing.
First of all, the clearance value is divided according to the accuracy grade of the bearing, which is P0/P6/P5/P4 in order, so that the clearance is 0 and the clearance is negative.
It can be said that the size of the clearance value determines the machining accuracy and difficulty of the slewing ring bearing, and it affects the machining accuracy of other parameters.
The clearance above 0 does not actually affect the rotation performance. If it involves positioning, measurement and control and repeated positioning, even if it stops immediately, a negative clearance is necessary.
If it is required for rotation, the size of the clearance value cannot determine the life and reliability of the bearing.
To put it bluntly, the clearance value is artificially divided into several steps one by one according to the size and diameter of the bearing, from P0-P4, the range is reduced in turn. The actual required clearance value is determined according to the specific requirements of the working conditions.
In fact, the accuracy level of the bearing should be more suitable for its requirements. For example, the clearance value can be narrowed, or it can be set to 0 clearance and small clearance. Wait.
The working condition is the only indicator that determines the bearing clearance. It cannot be done step by step, and the various parameter values of the bearing grade can be applied mechanically.
4.The warning signs of bearing wear or failure
Some of the premature failures experienced by slewing ring bearings can be prevented through careful monitoring of symptoms. One of the most basic indicators of slewing ring bearing problems is the condition of the lubricant. If metal particles or flakes are apparent, some form of wear is taking place.
Grinding, popping, or clicking noises from the bearing typically mean there is inadequate lubrication and/or excessive wear in the raceway.
Excessive play or movement signifies that the raceways are worn. As clearance increases, wear is usually accelerated, making close monitoring critical. The play, or clearance, in a slewing ring bearing is another important indicator of a problem. A new bearing is assembled with a specific amount of clearance to compensate for slight out-of-flatness encountered in a mounting structure. This clearance can increase dramatically due to wear.
An increase in torque or binding can mean that there is uneven wear in the raceway. If the turning torque of the bearing increases substantially or if the bearing has tight spots, this usually indicates an uneven load distribution.
With excavators, for example, the operator may notice a wobbling or rocking motion in the upper structure, especially when the digging arm is extended with a load. The operator may also sense a resistance to swing and find that the upper swings an inch or two past the point where it should have come to a stop. In advanced stages of wear, the bearing will pop and crack as the machine digs and wings.
By watching for symptoms of wear or failure, you can increase the life of the bearing and, when it becomes worn, have it remanufactured. Find out more about bearing remanufacturing and how it can save you time and cost compared to a new replacement bearing.
Troubleshooting of Marine Crane Slewing Bearing(Update 2022)
Before learning about large slewing bearings for marine cranes and marine machinery. To understand the standard and precision system of slewing bearing. Accuracy grades: Product accuracy covers four grades: P0, P6, P5, and P4.
Executive standard: general bearing GB/T307; slewing bearing JB/2300; shipbuilding industry CB/T3669; machinery industry JB/T10471; wind power bearing JB/T10705
1. The slewing bearing mechanism is composed of three parts: the supporting device, the slewing drive device and the turntable. Its important mechanical component– slewing bearing, is an important force-bearing component. It not only bears the self-weight of the rotating part of the crane, but also bears the vertical direction of the hoisting load.
The force of action and tipping moment. In the process of use, there must be wear and tear, and the performance of the related mechanical parts will gradually deteriorate or even be damaged. Therefore, the common faults of the slewing mechanism are also related to the mechanical parts. Accordingly, the failure analysis of marine cranes can generally be started from two aspects: mechanical failure and hydraulic system failure.
Experience shows that the common faults of the slewing mechanism mainly include excessive clearance of the slewing bearing (open movement), slow action of the slewing system (weakness) or motionless, abnormal system pressure, oil leakage, and inability to lock the slewing brake valve.
1.marine crane slewing bearing weak or unable to swing (system pressure is normal)
1. The hydraulic motor fails and the power cannot be output normally. Repair or replace it.
2. The failure of the reducer will affect the power transmission, check and adjust.
3. In case of overload, the lifting weight must be rechecked to avoid overload.
4. The overflow valve and manual control valve are faulty, check and adjust.
2. marine crane slewing bearing can not be rotated (system pressure is normal)
2. The large amount of rotation of the slewing bearing of the dock crane may have the following reasons:
1. It may be aged, it will be ground badly without butter, and the gap between the gear and the rotation is too large, all of which are ground.
2. The standard frame of the slewing bearing is less than 1 degree. But there will be some.
3. The steering reducer is broken.
4. There is a gap between the gears. Suggestions: If you want to change this state, you need to replace the slewing bearing and the gear of the slewing oil pump.
3. How to solve the abnormal noise when the ship crane slewing bearing swings back and forth
If the turntable of the ship crane swings back and forth, it will be more likely to cause danger. Therefore, in order to avoid the phenomenon of swinging back and forth, once such a fault occurs, it should be adjusted and repaired in time to avoid the dangerous phenomenon caused by the swinging of the turntable back and forth. Then, if the ship crane swings back and forth, how should it be adjusted?
1. Adjust the basic arm of the ship crane slewing bearing, so as to fix the basic arm and reduce the swing amplitude;
2. If the oscillation is caused by the excessive displacement distance of the outer ring, we need to adjust the gear backlash of the slewing bearing and the reducer;
3. When we adjust the slewing bearing of the ship crane, we should pay attention to the amplitude of the swing not exceeding 4mm, which can reduce the occurrence of danger.
Therefore, by adjusting the swing range of the turntable of the ship crane in the above manner, the danger of the ship crane caused by the excessive swing range of the turntable can be reduced. When the crane is working, the turntable vibrates or makes abnormal noises.
First, whether the marine crane slewing bearing clearance is too large, the slewing clearance is large, and the starting is not stable, and abnormal noises will occur.
Second, the marine crane slewing bearing motor parts are damaged or the slewing gear box parts are damaged.
Third, the marine crane slewing bearing support ball or raceway is damaged.
The marine crane slewing bearing of the wharf crane operates in a high temperature environment. The slewing bearing produced by our company can work normally at -30-+70. If the user needs a bearing with a lower or higher temperature, our company’s engineering and technical personnel can design it for you.
Our company can customize the high temperature resistant slewing bearing, which can be applied to high temperature 200. The high temperature resistant sealing strinvironment.
2. Precautions for the operation op is made of fluorine rubber, the high temperature resistant isolation block is made of aluminum alloy or copper alloy, and the high temperature resistant lubricating grease is used to ensure the stable performance of the small slewing bearing in the high temperature ef the slewing bearing of the dock crane Before the slewing bearing is installed, the installation surface of the main engine should be checked first. It is required that the support should have sufficient strength, the connecting surface should be machined, and the surface should be smooth and free of debris and burrs.
For those that cannot be machined to achieve the required flatness, special plastics with high injection strength can be used as fillers to ensure the accuracy of the installation plane and to reduce vibration. The ferrule of the wharf crane slewing bearing has a quenched soft belt area, which is marked with S on the end face of the ferrule. When installing, the position of the soft belt should be placed in the non-load area or the non-regular load area (the plug hole is always located in the soft area. belt).
3. How to maintain the slewing bearing of the quay crane in operation? After the slewing bearing of the quay crane is installed and put into operation, after 100 hours of continuous operation, the pre-tightening torque of the mounting bolts should be fully checked whether it meets the requirements, and repeated every 500 hours of continuous operation. Check the above once.
4. The quality requirements of the slewing bearing of the wharf crane The quality inspection of the marine crane slewing bearing can be divided into axial clearance and radial clearance according to the different detection methods. The radial clearance is the combination of the inner group, outer ring and rolling elements of the bearing. It is an important item for the inspection of ships with much higher quality standards in accordance with the national standard JB/T10471. Relative to CB/T.
1.What are roller bearings?Types and applications:
Roller bearings — also known as rolling-element bearings — are similar to ball bearings in that they are designed to carry a load while minimizing friction. However, roller bearings transmit loads using cylinder rolling elements, rather than balls, to maintain the separation between moving parts of the bearing. These versatile roller bearings can contain single or multiple rows of rolling elements; multiple rows can significantly improve radial load capacity. Also, the use of different roller shapes can further reduce friction and support both radial and axial loads.
While bearings can handle higher loads than conventional ball bearings, their applications are generally limited to low-speed operations. Many types of roller bearings are self-aligning, and are easily able to overcome misalignment and mounting issues — cutting down on maintenance, repair, and labor needs.
Roller bearings come in a wide range of shapes and sizes, and can be customized for specialized situations. Also, the use of flanges, cages, and multiple bearing rows can allow for higher performance to meet specific applications needs.
Rolling-element bearings have the advantage of a good trade-off between cost, size, weight, carrying capacity, durability, accuracy, friction, and so on. Other bearing designs are often better on one specific attribute, but worse in most other attributes, although fluid bearings can sometimes simultaneously outperform on carrying capacity, durability, accuracy, friction, rotation rate and sometimes cost. Only plain bearings are used as widely as rolling-element bearings. Common mechanical components where they are widely used are – automotive, industrial, marine, and aerospace applications. They are products of great necessity for modern technology.
The rolling element bearing was developed from a firm foundation that was built over thousands of years. The concept emerged in its primitive form in Roman times; after a long inactive period in the Middle Ages, it was revived during the Renaissance by Leonardo da Vinci, developed steadily in the seventeenth and eighteenth centuries.
There are thousands of different types of roller bearings available to meet specific application requirements. Emerson Bearing offers a broad selection of roller bearings, including the following popular types:
These roller bearings feature rollers that are longer than their diameter, and can tolerate higher loads than ball bearings. Our cylindrical roller bearings can carry heavy radial loads and are able to be used in high-speed applications.
Spherical roller bearings
These can carry heavy loads even when dealing with misalignment and shaft deflection. They can be designed to have cylindrical or tapered bores for mounting with or without a sleeve adapter. Available with various internal clearances and retainer options, spherical roller bearings can handle axial loading in either direction as well as heavy shock loads. These bearings are available in bore dimensions ranging from 20 mm to 900 mm.
Needle roller bearings
This type of roller bearing is thinner than conventional roller bearings and can be designed with or without an inner ring. Needle roller bearings are ideal for dealing with radial space constraints in heavy-load, high-speed applications. Drawn cup styles allow for high load capacities and large grease reservoirs while still offering a slim cross-section design. These bearings are offered with inch or metric seals.
Taper roller bearings
These roller bearings can support radial and thrust loads. They can only handle unidirectional axial loads, so a second laterally reversed bearing is required for counterstay. Taper roller bearings are available in inch and metric sizes. Roller bearings are used in a wide range of applications, from heavy equipment and machinery to power generation, manufacturing, and aerospace.
2.What are the advantages of roller bearings?
The rolling bearing is a kind of precise mechanical element that turns the sliding friction between the shaft and the axle seat into rolling friction, in order to reduce the friction . Ball bearings, roller bearings and needle roller bearings all belong to the rolling bearings.
Advantages of rolling bearings
1, the friction resistance and the power consumption are small, the mechanical efficiency is high, and is easy to start.
2, size standardization, interchangeability, easy to install and disassemble,easy to repair.
3. The structure is compact, the weight is light, and the axial size is narrower. 4. High precision, large load and long service life. 5. Some bearings have the performance of automatic heart adjustment. 6. It is suitable for mass production, the quality is stable and reliable,and the production efficiency is high.
7, the friction torque of the transmission is much lower than that of the fluid dynamic pressure bearing, so the friction temperature rise and the power consumption are low.
8, the axial size is less than the traditional fluid dynamic bearing. 9. The combined load of radial and thrust can be borne simultaneously.
10. Within a large load – velocity range, the unique bearing design can achieve excellent performance.Disadvantages of rolling bearings
1. The noise is great. 2. The structure of the bearing seat is complex. 3. The cost is high. 4. Even the bearings are lubricated well, installed correctly,well sealed, and the operation is normal, they will eventually fail because of the fatigue of the rolling contact surface.
3.What is the difference between a roller bearing and a ball bearing?
A bearing is a cylindrical unit that is used to provide low-friction movement for a bushing or bearing block. A ball bearing is a spherical unit that accomplishes the same objective as a roller bearing. The real difference has to do with the contact surface between the bearing and the rail.
For ball bearings (assuming a perfectly spherical bearing and no deformation), the contact surface is just a single point. Even once deformation is accounted for, the amount of surface where the ball is contacting the rail is limited. This creates an inherent strength limit for the balls. Roller bearings on the other hand, have an entire line of contact. This greatly increases the rigidity, stability, and maximum load capacity of the system.
Slewing Bearing/slewing ring bearing:the gear accuracy grade and the slewing bearing installation.
Table of Contents
1.The gear accuracy grade of the slewing bearing and the feasibility and practicality of gear grinding
Generally, the slewing bearing can have external and internal teeth, and the tooth profile can be helical, half-tooth, tooth surface quenching, and tooth surface tempering. In order to improve the gear accuracy level, tooth grinding is a separate process. Special instructions in the drawings.
So, the subject of this article, talk about the gear accuracy grade of the slewing bearing and the feasibility and practicality of gear grinding.
It should be understood that the reason why the rotary slewing bearing is used as a rotating mechanism is that it is easy to maintain and maintain, and the other is to use the low-speed and heavy-duty characteristics of the slewing bearing. In other words, the slewing bearing itself, as a precision component, is actually a customized product.
The gear accuracy grade is usually indicated as 10/9/8, and 7/6/5 generally requires gear grinding. The gear grinding process is to achieve precise meshing and precise pointing and positioning. Most do not need to grind the teeth because the cost of grinding the teeth is very high.
2.Slewing Ring Bearing Installation Tips to Ensure Optimal Performance
While slewing ring bearings do perform heavy-duty functions often under the worst possible conditions, they must be treated as delicate instruments to ensure their accuracy and a long operating life. Following the installation procedures precisely is critical to ensuring the best possible performance.
While slewing ring bearings often perform heavy-duty functions under the worst possible conditions, they must be treated as delicate instruments to ensure their accuracy and a long operating life. Following the installation procedures precisely is critical to ensuring the best possible performance.
Slewing rings are vital to supporting heavy loads that must rotate to other positions in a precise manner. Devices that use slewing ring bearings include:
Massive construction cranes
Large solar tracking devices
Some types of military armament
Since the rotation of the mechanism demands accuracy to assure effectiveness and safety, the installation of slewing ring bearings requires precision to expect proper operation.
Complying with every detail of the instructions is necessary for proper installation and function. Here are some installation tips that highlight the need for proper cre of this paowerful yet sensitive equipment.
MAKE SURE SLEWING RINGS ARE SHIPPED AND STORED PROPERLY
When the manufacturer prepares slewing ring bearings for shipment, they are lightly lubricated, wrapped for delivery and packed in individual specialized containers.
After receiving, store the unit in a clean, dry place in the original packing material until installation. Ensure that all areas around the slewing ring bearings are free of grit and dirt.
ALWAYS INSPECT FOR DISTORTION OR INTERFERENCE FROM DEBRIS
Each component of the slewing ring bearing must be clean, unobstructed by even the smallest foreign object and precisely oriented. Problems may arise during operation when friction or out-of-balance situations occur. The load may tend to concentrate in a particular area, creating a malfunction or improper wearing.
ENSURE SUPPORT SURFACES ARE LEVEL AND STRONG
The supporting surfaces must be machined smooth and perfectly level. They need to have sufficient strength to remain rigid during operation to eliminate any possible vibration or buckling due to imbalance.
CHECK THE RING CIRCULARITY
Protecting all elements of the slewing ring bearing is essential. If the circularity of the slewing ring is compromised during shipment and handling, the slewing drive will not work properly. Slewing ring bearings should be transported and stored in purpose-built crates and kept in a horizontal position at all times.
Ensure that the lifting apparatus or sling used is sufficiently robust and capable of lifting and holding the ring during installation. The external gear teeth must have protection to guard against damage from any collision with other surfaces.
Slewing ring equipment should not be in storage for longer than six months. The raceways must always be kept greased and free of rust.
PROPER SEALING AND LUBRICATION
Installers should specify integral seals on bearings and incorporate shrouding to protect the gears and bearings
As with most metal machine parts, proper lubrication is essential to smooth operations and long life. For slewing ring bearings and gears, this process is crucial. Equipment will come with operating instructions that will advise a recommended frequency for lubricating. Lubrication schedules depend on the type of equipment and the amount of use.
Immediately after assembly, you should lubricate the gear with either a brush or spray-on. Gear lube is recommended at least every three months, depending on how rigorously the equipment is used.
DOUBLE-CHECK THE INSTALLATION INSTRUCTIONS AND PERFORM TESTS BEFORE USE
Follow the manufacturer’s installation directions to the letter.
During installation, the slewing rings should be rotated while bolts are tightened to determine if any tight spots are developing. Also, recheck the bolt torque to identify any change due to settling.
Once the ring bearing is in position, check for any gear backlash and bearing torque before putting into operation. Deviations can indicate a problem with the mounting process.
3.SLEW RING BEARING LUBRICATION MISTAKES YOU SHOULD AVOID
Lubrication is essential for maintaining the integrity of a slew ring bearing. When bearings are optimally lubricated, they not only run safely, but also reduce the potential for premature failure. In order to ensure that slew ring bearings are properly maintained, the following mistakes should be avoided.
1. RELUBRICATING ON A YEARLY BASIS
Every slewing ring bearing has a recommended relubrication period and should be followed closely. These recommendations include the typical amount of lubrication needed for a reapplication as well as the most appropriate time interval.
It’s important to note that these recommendations can depend on application. For example, it is recommended that a slewing bearing is lubricated every 100 hours of operation. If the application involves continuous rotating, then the slewing bearing should be lubricated after 20 hours of continuous use. In addition, slewing bearings that are mounted on idle equipment, or those that live in storage, should be lubricated every six months.
Contact your slew ring manufacturer regarding your specific application in order to get the most accurate recommendation.
2. NOT USING THE PROPER LUBRICANT
Not all lubricants are created equal. If two incompatible greases are accidentally mixed, the reapplication process will be ineffective. The following chart depicts examples of recommended lubricants.
Molub-Alloy 220 ES
Optimol Viscogen 0
Crater 2x Fluid
Ultra Prestige 2 EP
Cardium Fluid M or H
Centoplex 2 EP
Grafloscon C-SG 0 Plus
Gearite HDCF 4800
3. LUBRICATING TO THE POINT OF OVEFLOW
Although this is another misconception that varies by application, it is generally not recommended to lubricate slewing bearings so much so that the grease purges from the seal. The operating temperature and pressure within the cavity is likely to increase when excess grease is present. As a result, performance can be hindered.
4. ADDING ADDITIONAL GREASE WHENEVER BEARING MAKES NOISE
In some instances yes, your slewing bearing will need to be lubricated if it is making noise, but this is not true for all situations. Noisy slewing bearings can be a sign of internal damage as well. When internal damage occurs, extra lubricant will only provide temporary relief. Failure can occur if the root cause of the noise is not identified and remedied appropriately. If failure does occur, remove the slewing bearing as soon as possible and reach out to the bearing manufacturer to determine why the bearing was not compatible.
By avoiding the previously mentioned mistakes, you will be able to ensure that your slewing ring bearings are properly lubricated and performing as intended. If you have additional lubrication questions about your specific application, please reach out to us here.
The slewing ring bearing is mainly composed of inner and outer rings or upper and lower rings, rolling bodies, seals, etc., among which the main upper and lower rings of the bearing are forged from alloy steel. Because of the different shape of the rolling body and the installation form, the bearing is divided into:
Single row roller single volleyball rotary bearing.
The upper and lower rings of the bearing body are usually made of 42CrMo. After forging, they are machined and then tempered, and the racetrack surface is quenched. The quenching hardness of raceway surface is about HB256 ~ 279 and HRC 55 ~ 60 after quenching. The surface of raceway shall be ground after quenching, so that the surface roughness of the raceway shall not be less than 1.6 m.
The main upper and lower rings of the bearing should be inspected in the forging and processing process to ensure that there are no defects such as shrinkage, sand holes, pores and cracks beyond the permitted scope. The commonly used slewing bearing of the rotary device of the bucket wheel stacker and recharger mainly includes the forms of cross roller, three row roller and single row roller volleyball, among which the highest price is three row roller.
The single-row cross roller type structure is that the bearing roller is a single-row roller structure. The axes of all rollers form an Angle of 45° with the horizontal plane. The rollers are respectively installed in the 90° V-shaped groove between the inner ring and outer ring of the bearing. Single row cross roller slewing support is characterized by compact structure, light weight, small assembly clearance, high positioning accuracy and low cost.
Single row cross roller slewing support can bear axial force, tilting moment and larger radial force at the same time, it is widely used in medical equipment, lifting transportation, construction machinery and other products. Single row cross roller slewing support is not suitable for heavy duty and frequent working machinery equipment. At present, in order to reduce the cost, many manufacturers choose this kind of bearing as the rotary bearing of the stacker.
The single row roller single volleyball slewing bearing is two kinds of supporting parts which bear radial load and axial load respectively, namely, the roller bears axial load and the ball bears radial load. Some European manufacturers, after considering the cost factor, choose this kind of bearing as the rotary bearing of stacker.
Taking the bucket turbine as an example, the three-row roller slewing bearing is the most ideal slewing bearing for the bucket wheel stowage and reclaiming machine. Its characteristic is that its ability to bear axial load, radial load and overturning moment is larger than other bearings of the same size, and it has a relatively high service life in the bearings of the same size.
2.Spacers and cage for slewing bearing
For ball-type slewing bearings, spacers are generally used to eliminate the friction between the balls. a smaller diameter ball can be put into it every now and then . Contact and friction between the ball and the raceway is much lower than full ball type. The support of such a structure does not occur after long-term use. The same principle can also be used for roller bearings. For example, smaller diameter spacers can be used to separate vertical rows of rollers.
Due to the advantage of the ball type rotating conditions, the friction is not as uniform as the slewing bearing of the cage holding slewing bearing, but is significantly smaller and uniform than the full stuffed ball type. The bearings act as oscillating motions, crossed by left and right rotating for excavator & crane application, the friction is very uniform and small.
The ball type or roller type with Nylon spacers is characterized by simplicity and economy. The diameter of the ball or roller should be slightly smaller than the Nylon spacer, but the difference should not be distinguishable by the eye watch. The only disadvantage of this type of spacer element is that only half of the ball (roller) can be mounted on the raceway, and the load capacity is half of the full ball (column) support.
In order to remove the product defects, we could choose steel cage, so 80% of full space on raceway could be filled in steel ball which increase 60% loading moment than before. The new structure with metal contact closely which lead to the bigger friction than before.
3.Slewing bearing manufacturing process
Slewing ring bearing is also called slewing bearing. The main structure includes: inner ring, outer ring, rolling element and the retention of rolling element guide. It is an important transmission device in the equipment. It is used in machinery, light industrial machinery, metallurgical engineering machinery, medical machinery, and marine equipment. And other industries are widely used.
Raw materials of bearing nodes The raw material of the bearing support bearing is integrally hardened carbon bearing steel, and the bearing sleeve adopts surface hardened steel, generally made of 50Mn steel, such as: S48C, 42Cr, 5CrMnMo. The raw material billet is transported from the steel back to the raw material circle. The bearing steel needs to be processed to the size required. Generally, alloy saw blades should be used for cutting bearing steel, which have high quality, wear resistance, strength and hardness, heat resistance, corrosion resistance and other excellent properties.
Forging and pressing of supporting billets In the heating furnace, the billet is heated and forged into a round cake shape. More dense and streamlined, which can improve support and the future. In addition, the quality of the process directly affects the production of raw materials, thereby affecting production.
slewing support A steel ring machine is used to pass the steel blanks through the structured steel ring. The overall structure of the steel can be modified to improve the strength, plasticity, impact and other mechanical properties of the steel structure.
rough turning processing The steel ring is loaded into the machine tool, and the rough turning of the machining is performed, and various groove raceways are turned out. The steel ring is fixed on the gear milling machine, and the cutter produces teeth. The main purpose is to make the final ferrule the same shape as the final product, creating conditions for grinding machine processing.
Support quenching (heat treatment) After machining, through the quenching operation, the strength of the steel, the wear resistance of the performance, the strength and the metal are improved. Heat treatment is the high temperature treatment of the bearing ring after processing and turning, which affects the uniformity of carburization in the direct bearing ring, can improve the wear and characteristics of the bearing, and also affect the wear and life of the bearing.
ring support processing The steel work of the mounting hole is performed on the end face of the ring, the center and the center angle should be determined when the bearing is bored, and the drilling machine, hand-held electric drill and hand drill should be selected for operation.
fine turning processing Machining is to perform fine processing and trimming according to the finished bearing after the hole is opened to ensure the exquisite appearance of the car. The bearing support and the bearing surface processing accuracy of the finishing processing have an impact. The fine processing of the steel ring raceway surface is carried out. Modified the deformation of the origin of the former road.
Ring support operation The finished products (outer ring, inner ring, sub, roller) that have undergone various processing are integrated, such as: inserting steel balls, isolating blocks, and sealing sealing strips. Finished bearings.
Packing The finished equipment will be coated with anti-rust oil, packed and packaged, and will be cleaned and inspected by the factory inspector, and the qualified products will be certified and sold at the same time.The above is the relevant content about the manufacturing process and production specifications of the support bearing, including the relevant content of the support bearing material selection, bearing, automobile processing, heat treatment, grinding processing, and assembly, for your reference, in the actual process. If you have any questions, you can contact our engineers.
4.Slewing ring seal replacement standard
The slewing bearing is composed of inner ring, outer ring, rolling element, spacer, sealing strip, etc.
The standard for replacing the slewing ring sealing strip during work:
1. Clean up the sealing strip installation groove and remove oil stains;
2. Prepare the purchased quality sealing strip according to the length required by the original factory, and prepare 502 glue;
3. With a flat-blade screwdriver, slightly stretch the sealing strip expanded to an appropriate length and install it in the groove;
4. Cut the interface into an oblique opening, glue it with 502, and place the tape in the groove after solidification.
Special attention: Leaking grease is not a failure of the sealing strip (the sealing strip only serves to prevent dust from entering the interior, and cannot prevent the outflow of grease)
Then the oil leakage is caused by the following reasons:
1. Excessive lubrication of the slewing bearing;
2. The machine enters deep water and the grease deteriorates;
3. Sealing failure of hydraulic system components causes hydraulic oil to enter the slewing ring oil groove and overflow;
4. The slewing bearing is worn too much.
5.Friction resistance distance of slewing ring
Friction resistance distance of slewing ring The slewing ring is a kind of large bearing parts that can bear complex loads. It can support the above part of the slewing ring for slewing motion, and at the same time bear the effects of large axial force, tilting moment and radial force.
Slewing ring bearings are divided into four types according to different structures: four-point contact ball bearings, crossed cylindrical roller bearings, crossed tapered roller bearings and three-row cylindrical roller bearings. The three-row cylindrical slewing ring has three seats. 1 Analysis and calculation of friction torque
1.1 The mechanical calculation formula of friction resistance moment of slewing bearing is based on the formula: Tm=(2ωDN)/2. When the slewing bearing’s external dimensions and rollers are clear, the values of ω and D can be directly determined. Therefore, the friction resistance moment of the slewing bearing can be calculated The key step of Tm is to calculate the total pressure ΣN of all rollers.
The friction resistance distance
1.2 Model assumptions As the slewing bearing bears the axial force Fa, radial force Fr and overturning moment T at the same time. The actual rigidity of the inner and outer rings of the slewing ring, the dimensional accuracy of the rolling elements, the processing accuracy of the raceway and the matching tolerances between the components directly affect the force distribution of the rolling elements.
When calculating the force of the slewing ring by analysis, the following assumptions are required: Assume that the inner ring and the outer ring of the slewing ring are rigid bodies, and only elastic deformation occurs at the contact point of the rollers. The geometric dimensions of the rolling elements are exactly the same.
The roundness of raceways, the concentricity of different raceways, roughness and other factors all meet the ideal requirements. The pressure generated by the rolling elements on the raceway is continuously distributed.
Force analysis diagram
2 Numerical calculation method for frictional resistance moment of three-row roller slewing ring
Three-row roller slewing ring contains three ring gears, two horizontal raceways, and horizontal rollers are installed on the axis. The diameter of the upper horizontal roller is larger than the lower one. Sub diameter; a vertical raceway, the installation axis of the vertical roller. It can resist large axial force, radial force and tipping moment.
When analyzing the force of the three-row roller slewing ring, it is assumed that the frictional force of the rollers in the radial direction on the horizontal raceway and the frictional force in the vertical direction on the vertical raceway are zero.
The Nm caused by the axial external force Pa of the slewing ring and the tilting moment Pm caused by the ±Nm are borne by the rollers on the horizontal raceway, and the Nr caused by the radial external force Pr is borne by the rollers on the vertical raceway.
The vertical force Na and Nm have a pressure angle of 90°, and the horizontal force Nr has a pressure angle of 0°. Therefore, Na=f(Pa) =Pa/sin90°=Pa; Nm=f(Pm)=Pm/sin90°=Pm, Nr=f(Pr)=Pr/cos0°=Pr
The friction resistance distance of the following slewing bearings is relatively low.