Archive for month: April, 2019

Slewing bearing common faults and solutions

2019-04-02/in Industry News /by admin

Slewing bearings are a common mechanical part in industrial equipment. They have many good properties and advantages that can increase productivity in industrial production. However, in the long-term use of the slewing bearing, various failures will inevitably occur. The methods for solving various failures are as follows:

1. The newly purchased slewing bearing product is not flexible. Please check the production date of the slewing bearing. If the time is long (such as more than half a year) and the weather is cold, there may be a large viscosity of the grease in the raceway, which may cause malfunction (cold area, winter is more prominent).

Remedy: If it can work after the afterburning and no other abnormalities can be used normally; if there is abnormal noise, check whether there is serious trauma during transportation, and feedback the information to our company’s sales service department.

2. It is not flexible after installation. It may be that the mounting surface of the main assembly does not cooperate well with the mounting surface of the slewing bearing, so that the axial clearance of the slewing bearing after installation cannot compensate for the deformation of the slewing bearing, and the slewing bearing is in a negative clearance state, and the rolling elements are difficult to operate in the raceway (sometimes accompanied by different Sound); or poorly meshed gears; or foreign objects in the large and small gears. Remedy: a. Rework the host installation plane so that the installation plane meets the requirements; or use the gasket filling method.

b. Resize the gear meshing backlash as required, paying particular attention to the maximum position of the gear runout.

c. Check that there is no foreign matter in the meshing position of the large and small gears.

d. Replace a slewing bearing with a slightly larger gap.

(3) Inflexible operation during use

a. Lack of grease, fill as required

b. The sealing strip is damaged, causing foreign matter to enter the raceway (if the working condition is poor, the dust in the raceway invades the dust, etc.).

c. Check the meshing of the large and small gears, with or without foreign objects or broken teeth. If the above measures are taken, the slewing bearing cannot be rotated, and there may be a failure in the raceway. Please inform our after-sales service department.

2. The slewing bearing that has just been shipped from the factory will give a uniform sound of the rolling of the steel ball during idling, which is normal. The slewing bearing is accompanied by a different kind of abnormal sound when it is installed after installation, which is called abnormal noise.

(1) The slight abnormal sound of the new product when it is idling, it will naturally disappear after turning for dozens of laps. If it does not disappear, it may be caused by slight deformation of the slewing bearing during transportation. However, if the operation is flexible and normal, it can be installed and used with confidence, and it will disappear naturally after a period of use. If the sound is loud or after a period of use (usually 2-4 months) has not disappeared, you should contact me in time.

(2) After the assembly, abnormal operation occurs during the test run. It should be checked whether the installation surface is level and meet the requirements. If the unevenness of the installation surface does not meet the requirements, the negative gap of the raceway will be generated and the noise will be abnormal. The treatment method is the same as “the operation after installation”. “Flexible”; or poorly meshed gears, loose when tight, and excessively tight at the maximum position of the tooth jump to produce abnormal noise.

(3) Abnormal noise is generated during use. (First of all, it should be determined whether the sound is emitted by the slewing ring. Some steel structures or other components make a sound, which is often mistaken for the sound of the slewing ring. Therefore, the rotation of the slewing ring can be stopped. Other components are in normal operation to discriminate the source of the sound. There are several reasons: the grease is missing in the raceway, and the rolling body and the block collide to make a sound. This sound can be eliminated after oiling in time; the raceway is mixed with foreign matter such as sand and iron. Such as scraping, this situation is often accompanied by difficulty in turning (generally this situation is prone to occur in harsh environments). At the same time, it should also pay attention to whether the sealing strip is damaged; the mounting bolt is loose, resulting in elastic deformation of the slewing bearing, negative gap in the deformation position, etc., to eliminate the above situation, such as the slewing bearing still has abnormal noise, please contact me.

3. After the slewing bearing is loaded, the clearance is about 3-5 times of the factory inspection (three-point inspection method), and can be used continuously within this range.

(1) The mounting bolts are loose, causing them to shake during work. Please inspect all inner and outer ring mounting bolts and tighten as required.

(2) The steel structure supporting the slewing bearing is not rigid enough, and elastic deformation occurs during loading, resulting in overall swaying of the slewing bearing. Increase the strength of the supporting slewing bearing steel structure.

(3) Check whether the operation is overloaded and operate in strict accordance with the regulations.

(4) Long-term overloading and causing the raceway to collapse, and the clearance is too large. Please let me know if this happens.

4. When there is a broken tooth in the broken tooth slewing bearing, the site should be protected and the company’s after-sales service department should be notified immediately for analysis and processing. (1) Broken teeth are often directly related to installation, and there are mainly the following reasons:

a. When installing the large and small gears, the side gap is not adjusted properly, and the requirements are not met, resulting in poor gearing of the two gears during operation. The backlash should be adjusted as required.

b. The meshing gap adjustment is not performed with the pinion gear at the maximum position of the tooth jump as required, causing the pinion gear to become stuck when the meshing gear is engaged with the maximum position of the large gear tooth jump. The meshing adjustment should be made with the pinion in the position where the green paint is applied, and the test operation should be carried out after adjusting according to the requirements.

c. The axis of the large and small gears is not parallel. After installation, the large and small gears mesh poorly, causing broken teeth. It should be ensured that the two gear axes are parallel.

d. The slewing bearing mounting bolts are not tightly fixed, and the large and small gears are poorly engaged, causing broken teeth. The bolts should be tightened as required.

(2) aspects of use

a. Violation of the operating procedures, overload and tell the rotation, the host collides (sweep) obstacles and so on. It should be operated strictly in accordance with the operating procedures.

b. Foreign matter is caught when the slewing bearing is engaged with the pinion. The size of the gears should be clean and checked frequently. Common faults and troubleshooting methods for slewing bearings

Slewing bearing is an important device of industrial machinery. It is a mechanical “joint”. Without slewing mechanical equipment, there is no good activity. Therefore, daily troubleshooting is very important, which not only guarantees the service life of the slewing bearing, but also Improve the utilization of slewing bearings, reduce maintenance costs and reduce costs. The slewing bearing is a more professional mechanical device, and it is also a special load that can withstand large axial loads, radial loads and overturning moments, and combines various functions such as support, rotation, transmission and fixing. Large bearing with structure. In the course of use, it will inevitably cause damage to the bearing. Its maintenance and maintenance also needs to be very careful. What is the specific maintenance operation procedure? Below, I will summarize some points for you to pay attention to, and we will introduce the common faults and troubleshooting methods of the slewing bearing device.

1. Rolling surface metal peeling The slewing bearing rolling elements and the inner and outer ring raceways are subjected to periodic pulsating loads, thereby generating cyclically varying contact stresses. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the rolling element or the inner and outer ring raceways. Measures: First remove the roller or steel ball in the slewing ring to separate the inner and outer rings; then clean the raceway with gasoline; then use a sander (grinding wheel) to carefully produce around the needle stripping area of Microsoft Corporation of the United States. Grinding the hardened layer of the crack, grinding the bottom of the stripping layer; preheating the welding torch with the welding torch for the raceway, and welding with the medium carbon steel electrode (the electrode must be dried before use and used with baking) ), to make the solder layer slightly higher than the surface of the raceway 1-2mm.

2. The high-precision slewing bearing of the burned burn of the slewing bearing has a tempering color on the raceway and the rolling element. The causes of burns are generally insufficient lubrication, the quality of the lubricant does not meet the requirements or deterioration, and the bearing assembly is too tight. Measures: partial repair welding or insert repair, the local repair welding method is: firstly grind the residual crack base of the damaged part with a portable grinding wheel, clean it with gasoline (oil); use the welding torch to preheat in this part, when it reaches After a certain temperature, the medium carbon steel electrode is used to weld the shape of the tooth in the damaged part of the tooth, so that it is 1-2mm higher than the tooth surface of the party; the experienced machine repair fitter is selected according to the tooth shape test until the tooth The shape meets the requirements.

3. Plastic deformation of slewing bearing Non-uniform pits appear on the contact surface between the raceway and the roller with high precision slewing bearing, indicating that the bearing is plastically deformed. The slewing bearing is subjected to a large static load or impact load, and the local stress of the working surface exceeds the yield limit of the material, which generally occurs on a low-speed rotating bearing. Measures: If the deformation is serious or the area is large, the layered welding should be carried out in layers, and the temperature of the base metal should not be too high to cause deformation; this avoids the rapid cooling to produce welding cracks, and the heat preservation measures should be taken immediately after welding to gradually cool him. . After cooling, use a sander to smooth the repair layer so that it is slightly higher than the raceway surface. Gradually repair the repaired weld layer with a whetstone or metallographic abrasive cloth to make it conform to the height of the normal surface of the raceway, with the corresponding original curvature. The sample is tested until it is qualified; the grease is cleaned on the raceway and the roller (steel ball) and assembled into one.

4, the slewing bearing seat crack bearing seat ring cracks may be caused by high-precision slewing bearing too tight, high-precision slewing bearing foreign or inner ring loose, bearing containment parts deformation, mounting bearing surface processing and so on. Action: When a whole seat is damaged, it can be cut along the root of the tooth, and then the root of the tooth ring is shaped into a certain shape. Then, a tooth is registered and cut on the same kind of waste seat ring, and processed into a shape corresponding to the base material, and then placed in the groove, and the positioning is clamped by the seat-shaped template. In order to ensure the consistency of the seat distance, and use the double wire clamp to increase the value, and then weld around the seat with low carbon steel. Finally, the weld is flattened with a tool such as a file.

The difference of bearing capacity of different types of bearings.(slewing ring bearing)

2019-04-01/in Industry News /by admin

Deep groove ball bearings are the most common type of rolling bearings. The basic deep groove ball bearing consists of an outer ring, an inner ring, a set of steel balls and a set of cages. The deep groove ball bearing types are single row and double row. The deep groove ball structure is also divided into two types: sealed and open. The open type refers to the bearing without sealing structure. The sealed deep groove ball is divided into dustproof seal and oil proof. seal. The dust seal cover material is stamped from steel plate, which is simple to prevent dust from entering the bearing raceway. The oil-proof type is a contact type oil seal, which can effectively prevent the grease inside the bearing from overflowing.

Deep groove ball bearings are mainly subjected to radial loads and can also withstand radial loads and axial loads. When it is only subjected to radial loads, the contact angle is zero. When the deep groove ball bearing has a large radial clearance, it has the performance of an angular contact bearing and can withstand a large axial load. The deep groove ball bearing has a small friction coefficient and a high limit speed.

The deep groove ball bearing has a simple structure and is easy to achieve high manufacturing precision compared with other types, so it is easy to be mass-produced in series, and the manufacturing cost is also low, and the use is extremely common. In addition to the basic type, deep groove ball bearings also have various modified structures, such as: deep groove ball bearings with dust cover, deep groove ball bearings with rubber seals, deep groove ball bearings with snap grooves, and Deep groove ball bearings with large load capacity of ball notches, double row deep groove ball bearings.

Deep groove ball bearings generally use steel stamped cages or brass solid cages. When the outer diameter is less than 400 mm, the steel stamping cage is not added with a post code. When the outer diameter is larger than 400 mm, the brass solid cage is not used with a post code.

1.Self-aligning ball bearing

The self-aligning ball bearing is a bearing equipped with a spherical ball between the inner ring of the two raceways and the outer ring of the spherical raceway.
The center of curvature of the outer raceway surface is identical to the center of the bearing, so it has the same self-aligning function as the self-aligning ball bearing. When the shaft and outer casing are deflected, they can be adjusted automatically without increasing the bearing load.

Spherical roller bearings can withstand radial loads and axial loads in both directions. The radial load capacity is large, and it is suitable for heavy load and impact load. The inner ring inner diameter is a tapered bore bearing that can be mounted directly. Or use the adapter sleeve and the removal cylinder to mount on the cylindrical shaft. The cage uses a steel stamping cage, a polyamide forming cage and a copper alloy cage.

The self-aligning ball bearing has two structures of a cylindrical hole and a tapered hole, and the material of the cage is steel plate, synthetic resin and the like. The characteristic is that the outer ring raceway has a spherical shape and has self-aligning property, which can compensate the error of the heart ball bearing by different degrees of heart and shaft deflection, but the relative inclination of the inner and outer rings must not exceed 3 degrees.

Can withstand large radial loads while also withstanding a certain axial load. The outer ring raceway of this type of bearing is spherical, so it has the function of self-aligning. When the shaft is bent or tilted so that the center line of the inner ring and the center line of the outer ring are inclined no more than 1°~2.5°, the bearing can still work.

The inner diameter of the self-aligning ball bearing is cylindrical or conical. The conical inner bore has a taper of 1:1 2 or 1:30. In order to enhance the lubrication performance of the bearing, an annular oil groove and three oil holes are machined on the outer ring of the bearing.

It is mainly subjected to radial loads and can withstand small axial loads. The axial displacement of the shaft (housing) is limited to the clearance limit, and has automatic self-aligning performance, allowing normal operation under the condition that the inner and outer sides are relatively inclined, and is suitable for the parts in which the support seat hole cannot strictly guarantee the coaxiality.

The self-aligning ball bearing with dust cover and sealing ring has been filled with the proper amount of grease. It should not be heated or cleaned before installation. It does not need to be relubricated during use. It can adapt to operating temperature – 30 °C to + 120 °C. between. Main purpose of self-aligning ball bearings: Suitable for precision instruments, low noise motors, automobiles, motorcycles and general machinery, etc. It is the most widely used type of bearing in the machinery industry.

2. Cylindrical roller bearing

Cylindrical rollers and raceways are line contact bearings. Load capacity, mainly bear radial load. The rolling element has little friction with the ferrule rib and is suitable for high speed rotation. According to the ferrule with or without ribs, it can be divided into single row cylindrical roller bearings such as NU, NJ, NUP, N, NF, and double row cylindrical roller bearings such as NNU and NN. The bearing is a structure in which the inner ring and the outer ring are separable.

Cylindrical roller bearings with no ribs on the inner or outer ring, the inner and outer rings can move relative to the axial direction, so they can be used as free end bearings. A cylindrical roller bearing with a single rib on one side of the inner and outer rings and a single rib on the other side can withstand a certain degree of axial load in one direction. Steel stamping cages or copper alloy solid cages are generally used. However, some use polyamide shaped cages.

The cylindrical roller is in line contact with the raceway and has a large radial load capacity. Suitable for both heavy and shock loads, as well as for high speed rotation.

Cylindrical roller bearing raceways and rolling elements are geometric. After the improved design, the new load-bearing capacity, the new structural design of the rib and the roller end face not only improve the axial bearing capacity of the bearing, but also improve the lubrication conditions of the contact area between the roller end face and the rib, and improve the lubrication condition. Bearing performance.

The cylindrical roller is in line contact with the raceway and has a large radial load capacity. Suitable for both heavy and shock loads, as well as for high speed rotation.

3.Single row angular contact ball bearings

Single row angular contact ball bearings can only withstand axial loads in one direction and will cause additional axial forces when subjected to radial loads. And can only limit the axial displacement of the shaft or housing in one direction. Angular contact ball bearings have a contact angle of 40 degrees and can withstand large axial loads. Angular contact ball bearings are non-separable designs with different shoulder heights on the sides of the inner and outer rings. In order to increase the bearing capacity of the bearing, the shoulder on one side is machined lower, so that the bearing can be loaded with more steel balls.

Double row angular contact ball bearings can withstand large radial loads and mainly combine radial and axial load and moment loads, limiting axial displacement of both sides of the shaft. Mainly used to limit the axial displacement of the shaft and the shell. The tiltability between the inner and outer rings of the double row angular contact ball bearing is limited. The allowable tilt angle depends on the internal clearance of the bearing, the bearing size, the internal design and the action.

The force and moment on the bearing, and the maximum allowable tilt angle should ensure that there is no excessive additional stress in the bearing. If there is a tilt angle between the inner and outer rings of the bearing, it will affect the life of the bearing, and at the same time, the bearing running accuracy will decrease and the running noise will increase. Double row angular contact ball bearings typically use a nylon cage or a brass solid cage.