What material is good for the slewing bearing and how should it be selected?

The material of the slewing bearing directly determines the performance and service life of the bearing. At present, the main structure of bearings on the market is mostly made of bearing steel, which has the characteristics of corrosion resistance and stability. Of course, in addition to bearing steel, there are also metal materials such as aluminum alloy or copper. In addition, the sealing ring and cage of the bearing may be different from the material of the main body of the bearing. The following slewing bearing manufacturers will share what material is good for the slewing bearing.

What material is good for the slewing bearing?

Slewing Bearings

1. Material of ferrule and rolling element

The early slewing bearing used 45# steel, but it was gradually eliminated due to poor modulation performance in the later period. In the current more common processing technology, the slewing bearing rolling element adopts integrally hardened carbon chromium bearing steel. The grade is made of GCr15 or GCr15SiMn steel; the ring of the slewing bearing is made of surface hardened steel, and if there is no special requirement, it is made of 50Mn steel. But sometimes customers also choose to customize other grades such as 42CrMo, 40Cr, etc. The following describes the characteristics of these grades of steel.

(1) As a high-carbon steel, 42CrMo has good quenching and quenching properties and is an ideal material for slewing bearings.

(2) 50Mn has good hardenability and is also a high-quality choice for slewing bearings.

(3) 40Cr is also good in terms of mechanical properties, and it is still in the exploration and practice stage.

(4) GCr15 small slewing bearing can be selected, but it is generally not recommended to use it because of the troubles caused by full quenching in the process of milling and drilling.

2. Material of cage

Cages for slewing bearings have structural forms such as integral, segmented, and isolated block types. The types of cage materials are: low carbon steel stainless steel cage, bakelite/plastic (nylon) cage, brass/bronze/aluminum alloy cage, etc. The spacer type is made of polyamide 1010 resin, ZL102 cast aluminum alloy, etc. .

The characteristics of various material bearing cages are as follows:

(1) Steel bearing cage: It is often cold stamped from 08 and 10 carbon steel sheets. Commonly used steel cage materials include 20, 30, 45, 0Cr18Ni9, 1Cr18Ni9Ti, 40CrNiMo, ML15, ML20, etc., which are commonly used materials in bearing cages, which are solid, durable and stable.

(2) Non-ferrous metal bearing cage: Different from steel, non-ferrous metal has its special properties. For example, aluminum alloy has the characteristics of low density, good thermal conductivity, and good corrosion resistance; copper alloy has good thermal conductivity, low friction coefficient, Features such as good formability and high use temperature; zinc-aluminum alloy has the advantages of low cost, low density, and excellent performance.

(3) Non-metallic cage: non-metallic cage materials mainly include polymers and their composite materials, including nylon, phenolic tape, polytetrafluoroethylene, etc. The polymer material has good strength and elasticity matching, which can effectively reduce the heating and wear of the bearing.

3. Material of sealing ring

Bearing sealing materials are generally commonly used sealing materials, mainly: nitrile rubber, silicone rubber, fluorine rubber, EPDM, fluorobutadiene rubber, polytetrafluoroethylene, polyurethane rubber, acrylic rubber, Anaerobic glue, etc.

The sealing ring of the slewing bearing is made of oil-resistant rubber or NBR nitrile rubber. Compared with nitrile rubber, hydrogenated nitrile rubber has better oil resistance, but if you are not too demanding on oil resistance, use nitrile rubber, because hydrogenated nitrile rubber is relatively expensive. Nitrile rubber also has a certain degree of acid and alkali resistance. However, silica gel should be selected if the requirements for oil resistance and acid and alkali are higher, but its price is higher.

How to choose the material of the slewing bearing

Slewing Bearings

The slewing bearing manufacturer said that the materials used in slewing bearings should be analyzed based on the current level of slewing bearing production technology. It is recommended that the materials of bearing rings, rolling elements, cages, and sealing rings should first consider the following materials.

1. Material of rolling element: GCr15SiMn is generally used for rolling element.

2. Ring material: 50Mn is used for the slewing bearing ring, but sometimes 42CrMo is used to meet the needs of the host in special applications.

3. Cage material: The cage has different structure types such as integral type, segmented type and isolated block type. The integral or segmented retainer adopts 20# steel or ZL102 cast aluminum alloy. The isolating block holder adopts polyamide 1010 resin, ZL102 cast aluminum alloy or QA110-3-1.

4. Sealing ring material: The slewing bearing should be made of oil-resistant rubber, fluorine-containing rubber, and oil-resistant nitrile rubber. The clearance of the slewing bearing The clearance of the slewing bearing is mainly used to compensate the manufacturing error and installation error of the slewing bearing supporting parts and the relevant host assembly parts to ensure the normal use of the bearing. According to the structure type/tolerance class of the slewing bearing and the pitch circle diameter of the rolling element group, the clearance value or the interference amount of the slewing bearing.

The above is the introduction of the slewing bearing manufacturer on the material of the slewing bearing. The bearing materials mentioned are all suitable for slewing bearings, but the specific use environment and performance requirements may have different requirements for the bearing materials. Please follow the actual situation. Choose the situation.

Slewing bearing maintenance methods and maintenance precautions

There are many types of bearings, and the fields and equipment used by each type of bearing will be different. Among them, the slewing bearing can be rotated and used in many equipment and machines. It can be said to be the scope of use. There is a very wide range of bearings, so what are the maintenance methods of the slewing ring and what are the precautions in the maintenance process? The slewing ring manufacturer gave us the following detailed introduction.

Maintenance method of slewing bearing

1. After 100 hours of operation of the slewing ring, the pre-tightening force of the bolts should be checked, and every 500 hours of operation thereafter, sufficient pre-tightening force must be maintained.

2. When the slewing ring is in use, if noise, impact, or power suddenly increases, it should be shut down immediately for inspection, troubleshooting, and disassembly and inspection if necessary.

3. The raceways of the slewing bearing are regularly filled with grease. Generally, the ball bearings are refueled every 100 hours of operation, and the roller bearings are refueled every 50 hours.

4. The tooth surface of the slewing bearing should be cleaned of debris frequently and coated with corresponding grease.

5. The slewing bearing and slewing ring tooth surface should be cleaned up for 10 shifts, and grease should be reapplied.

Matters needing attention in maintenance of slewing bearing

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1. The mounting support of the slewing ring must have sufficient rigidity and the mounting surface should be flat. The support should be subjected to stress relief before assembling the slewing ring. The slewing bearing and slewing ring should be repaired and maintained to reduce the deformation of the slewing ring support. The support should be assembled during assembly. The contact surface with the slewing bearing must be cleaned.

2. When using slewing bearings and slewing bearings, attention should be paid to changes in noise and slewing resistance torque. If there is any abnormality in the maintenance of slewing bearings and slewing bearings, they should be disassembled for inspection. The slewing bearings must be hoisted or stored horizontally, not vertically. Lift or store to avoid deformation.

3. Before the bolts are tightened, the slewing bearing and slewing support should be checked for gear meshing. The meshing condition should meet the requirements of gear accuracy, that is, the contact spots distributed on the tooth surface after the gear pair runs under slight braking. The tooth height direction is not less than 25%, and the tooth length direction is not less than 30%.

4. Slewing bearing and slewing ring In order to ensure the reliability of bolt work and avoid the lack of bolt pre-tightening force, the slewing bearing and slewing ring should be checked for the pre-tightening torque of the bolts after 100 hours and 500 hours of operation of the slewing ring. The pre-tightening torque should be checked every 1000 hours of work.

The service life of the slewing ring during work is directly proportional to the maintenance performed on it. Good maintenance of the slewing ring is also a way to avoid the failure of the slewing ring. The maintenance methods of the slewing ring above are only part of it. Friends who want to know can check our company website. The slewing ring produced by LDB Bearing Co., Ltd. is of good quality, which can effectively improve labor productivity and equipment stability. You are welcome to call our hotline or leave a message at the bottom of the website.

How to distinguish the authenticity of a slewing bearing from its appearance?

Fake goods are a hateful existence for all walks of life. Many fake and inferior products carry the same outer packaging as the regular brand, but they are among the failures of Jinyu. Not only the product quality cannot be guaranteed, but it may even be in use. During the process, the maintenance and shutdown of the machine caused unpredictable economic losses. So how should we distinguish the true and false of the slewing ring from the appearance when we buy the slewing ring every day? The editor is here today.

First, eight counterfeit methods of slewing ring

Slewing Bearings

1. Material fraud: use iron or carbon steel to make slewing bearings, or repair scrap bearings. The former will cause insufficient hardness of the bearing, and the latter will cause insufficient bearing accuracy. Once these slewing bearings are used on bearings that require high accuracy and bearing hardness, they can easily cause machine failures.

2. Falsified outer packaging: Brand the inferior slewing ring or bearing produced by a small factory with the trademark of a large manufacturer, and counterfeit the inner and outer packaging and the certificate of conformity of the large-brand product. In this way, you can use the brand influence of major manufacturers to broaden the sales of your products.

3. Falsified sales channels: users, distributors, agents, or even counterfeit manufacturers’ spot sales outlets of well-known brands. Let consumers not be able to judge true and false, and make wrong judgments.

4. Pretend to be inferior: use inferior bearings as bearings. In the production process of bearings, defective products will be more or less produced, and they will generally be scrapped. Some black-hearted businesses will pretend to be defective products for sale, but the quality of the products is difficult to guarantee.

5. Accuracy fraud: use ordinary bearings to pretend to be high-precision bearings. Precision bearings have different requirements for the accuracy of various parts during production. Compared with ordinary bearings, the requirements will be relaxed. This way, the common means of posing as precision slewing bearings is also very abhorrent.

6. Fake goods for sale: slewing bearings are usually purchased in large quantities when they are sold. Some merchants take advantage of the buyer’s mentality that they will not check one by one, and sell them together with fake goods, and the product quality will vary. There is a bad situation.

7. Price fraud: In order to increase profits, businesses sell fake goods at high prices and use fake prices.

8. Look at people to deliver goods: When selling slewing bearings, merchants will provide selective supplies according to the seller’s specific conditions. If buyers want cheap goods, they will give fake goods. If they want good quality, they will give genuine goods. I don’t know how to do it. Those who only bargain think that they are taking advantage of it, but they don’t know that they may buy fakes.

Second, the method of identifying the true and false from the appearance of the slewing ring

Slewing Bearings

1. Look at the clarity of the stamp

How to distinguish the authenticity of a slewing bearing from its appearance? Each bearing product will have its brand name, label, etc. printed on the bearing product body. Although the fonts are very small, the products produced by regular manufacturers are printed with steel stamping technology, and they are pressed before heat treatment. Therefore, although the fonts are small, they are deeply recessed and very clear. Normally, the fonts of counterfeit products are not only blurred. Due to the rough printing technology, the fonts float on the surface, and some of them can even be easily erased by hand or have serious manual traces.

2. Listen to the noise inside the bearing

Hold the inner sleeve of the bearing with your left hand, and turn the outer sleeve with your right hand to make it rotate slightly. Listen for noise during the operation of the bearing. Due to the backward production conditions of most counterfeit products and the purely hand-made workshop operation, the bearing body will inevitably be mixed with impurities such as dust and sand during the production process. Therefore, noise or unsmooth operation may occur when the bearing rotates. phenomenon. This is the key to judging whether the product comes from a regular manufacturer’s brand product that has strict production standards and is operated by a machine.

3. See if the surface is clean

Whether there are turbid oil stains on the surface, we should pay special attention to it when buying imported bearings. Since there is still a certain gap between domestic anti-rust technology and foreign advanced manufacturing countries, it is easy to leave thick oil marks when anti-rust treatment on the bearing body, which feels sticky and sticky when touched by hand, while foreign original There is almost no trace of anti-rust oil on the imported bearings. According to industry insiders, particularly careful people can smell a special smell on imported bearings, which is the smell of anti-rust oil.

4. Look at the chamfer

Whether the chamfer of the slewing ring is produced is also closely related to the production technology level of the bearing manufacturer. Therefore, the neat degree of the chamfer can judge the technological level of the bearing. The so-called chamfer of the bearing is the junction of the horizontal plane and the vertical plane. Due to the limitation of production technology, the counterfeit bearing products are not handled satisfactorily at these corners, which we can easily distinguish.

5. Look at the packaging of the bearing

The packaging is divided into inner packaging and outer packaging. After the bearings are manufactured and passed the inspection, they will be cleaned and anti-rust treated, and then placed in the inner packaging to achieve waterproof, moisture-proof, dust-proof, shock-proof, and maintain the quality and accuracy of the bearing And the purpose of facilitating use and sales.

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

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

(2) General anti-rust period packaging: one year anti-rust period, suitable for general-purpose bearings.

(3) Long anti-rust period packaging: two years anti-rust period, suitable for special and precision bearings.

The inner packaging materials of the bearing include polyethylene plastic tube (box), kraft paper, plain and wrinkled polyethylene composite paper, paper box, polyethylene or polyethylene plastic film, nylon fastening tape or plastic woven fastening tape, waterproof high-strength plastic tape , Burlap bags, etc. All of the above materials need to ensure that the corrosion resistance test of the material is qualified.

How to distinguish the true and false of the slewing ring from the appearance can be judged from the above aspects. In addition, you can judge the approximate price range based on the understanding of the bearing and the market situation of the bearing. As long as you are not greedy and bargaining excessively, you can also confirm the place of purchase. It is difficult to distinguish true from false sources through informal sources, and bearings can basically be bought. The slewing bearings produced by our Kuoyi Longda Bearing Co., Ltd. are all qualified products that have passed quality inspections. If you have any needs, please feel free to inquire.

What are the repair processes for slewing bearings?

The slewing bearing is also called the slewing ring. It is a new type of mechanical parts. It is composed of inner and outer rings, rolling elements, etc. The slewing ring is a large-scale bearing that can withstand comprehensive loads, and can withstand larger axial and diameter at the same time. Bearing for load and overturning moment.

Generally, it is widely used in industry, and the effect of use is very good. The application of slewing bearings is special, and it must be operated under continuous shock, vibration, and overload. Therefore, the control of production technical parameters in the product manufacturing process is also It is more rigorous, with high bonding strength, no shedding, no hard spots, high surface finish, and adjustable hardness. However, damage is still inevitable, which requires special repair techniques to ensure the flexibility of the later application of the slewing ring.

Repair process of slewing bearing

Slewing Bearings

1. Low temperature iron plating method

Low-temperature iron plating is a commonly used method for repairing shaft parts in the industry, and it has a long history of application in other mechanical maintenance industries. Low-temperature iron plating is an electroplating technology with a fast iron plating speed. The one-time iron plating has a large thickness, a relatively mature process and high production efficiency. It is suitable for repairing the surface of agricultural machinery transmission shafts or parts.

2. Thermal spraying method

Thermal spraying method mainly uses high-speed airflow to spray molten metal material on the surface of partially worn parts, and then the size can be restored after processing. Thermal spraying technology includes many methods such as flame spraying, electric spraying and plasma spraying. The additional materials for spraying are often better than the raw materials, so after the slewing bearing is repaired, the parts in terms of wear resistance and corrosion resistance have been greatly improved.

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3. Surfacing method

The surfacing method is to use the welding process to surfacing a layer of welding material on the worn parts of the part, and then restore the original matching size of the part through mechanical processing. The surfacing process can achieve different material repair effects through the selection of welding rods or wires. The process has the advantages of high material strength after repair and faster repair speed, and is suitable for repairing parts with greater wear.

The performance of the correctly repaired bearing is equivalent to that of the new bearing, and all parameters such as clearance can meet the requirements of use. It is important to understand and identify the degree of damage to choose the correct repair plan. Bearing repair requires long-term technical accumulation and comprehensive basic data storage. Professionally trained personnel can judge whether the bearing needs to be repaired. Timely routine inspections, preventive maintenance and vibration analysis can grasp the appropriate repair time in time, so as to help companies economically repair damaged bearings.

Inventory of common slewing bearing damage failure causes analysis and solutions

It is common for bearings to fail during operation, so there is no need to make a fuss. In the event of a failure, the key to determining the cause of the damage and handling it Today, the editor has counted some common slewing bearing damage failure causes analysis and solutions.

 Crack defects

Trouble phenomenon: partly notched and cracked.

1. The cause of the failure

①Excessive impact load; ②Excessive interference; ③Large peeling; ④Friction cracks; ⑤Poor accuracy of the installation side (too large corner round); ⑥Poor use (a copper hammer is used to insert large foreign objects).

2. Solutions

①Check the conditions of use; ②Set appropriate interference and check materials; ③Improve installation and use methods; ④Prevent friction cracks (check lubricant); ⑤Check the design around the bearing.

Rotation of slewing bearing is not flexible

Trouble phenomenon: bearing heating, jitter, stuck.

1. The cause of the failure

①The clearance is too small (including the clearance of the deformed part); ②Insufficient lubrication or improper lubricant; ③Excessive load (excessive preload); ④The roller is skewed.

Slewing Bearings

2. Solutions

①Set proper clearance (increase the clearance); ②Check the type of lubricant to ensure the amount of injection; ③Check the conditions of use; ④Prevent positioning errors; ⑤Check the design around the bearing (including heating of the bearing).

The hardness layer falls off

Trouble phenomenon: the running surface is peeled off, and it is obviously convex and concave after peeling off.

1. Reason

①Improper use due to excessive load; ②Poor installation; ③Poor precision of shaft or bearing box; ④Too small clearance; ⑤Intrusion of foreign matter; ⑥rusting; ⑦Hardness reduction caused by abnormal high temperature

2. Solutions

①Re-study the operating conditions; ②Re-select the bearing; ③Reconsider the clearance; ④Check the machining accuracy of the shaft and the bearing housing; ⑤Research the design around the bearing; ⑥Check the installation method; ⑦Check the lubricant and lubrication method.

Slewing Bearings

Scratches and jams

Trouble phenomenon: rough surface, accompanied by micro-dissolving; scratches between ring ribs and roller end faces are called jams

1. Reason

① Poor lubrication; ② Foreign matter intrusion; ③ Roller deflection caused by bearing tilt; ④ Oil breaking on rib surface caused by large axial load; ④ Surface roughness; ⑤ Large rolling element sliding.

2. Solutions

①Re-study lubricants and lubrication methods; ②Check the conditions of use; ③Set appropriate preload; ④Strengthen the sealing performance; ⑤Use the bearing normally.

The cage is damaged

Trouble phenomenon: loose or broken rivet, broken cage.

1. Reason

①Excessive torque load; ②High-speed rotation or frequent speed changes; ③Poor lubrication; ④Entrapped foreign objects; ⑤Large vibration; ⑥Poor installation (installation in tilted state); ⑦Abnormal temperature rise (resin cage).

2. Solutions

①Check the operating conditions; ②Check the lubrication conditions; ③Re-study the selection of the cage; ④Pay attention to the use of bearings; ⑤Study the rigidity of the shaft and the bearing box.

Rusty corrosion on the surface of the slewing bearing

Trouble phenomenon: Part or all of the surface is rusty, and it is rusty in the form of pitch of rolling elements.

1. Reason

①Poor storage condition; ②Improper packaging; ③Insufficient rust inhibitor; ④Intrusion of moisture, acid solution, etc.; ⑤Hold the bearing directly by hand.

2. Solutions

①Prevent rust during storage; ②Strengthen the sealing performance; ③Check the lubricating oil regularly; ④Pay attention to the use of bearings.

Abrasion

Trouble phenomenon: red rust-colored wear particles are produced on the mating surface.

1. Reason

①Insufficient interference; ②Small bearing swing angle; ③Insufficient lubrication (or in a non-lubricated state); ④Unstable load; ⑤Vibration during transportation.

2. Solutions

①Check the interference and lubricant coating status; ②The inner and outer rings are packaged separately during transportation, and pre-pressure is applied if they cannot be separated; ③Reselect the lubricant; ④Reselect the bearing.

Slewing Bearings

Wear

Phenomenon: Surface wear, resulting in dimensional changes, often accompanied by abrasion and wear marks

1. Reason

①The lubricant is mixed with foreign matter; ②The lubrication is poor; ③The roller is skewed.

2. Solutions

①Check lubricant and lubrication method; ②Strengthen sealing performance; ③Prevent positioning error.

Indentation bruises

Trouble phenomenon: surface pits caused by stuck solid foreign objects or impact and scratches caused by installation

1. Reason

①Intrusion of solid foreign matter; ②Insert the peeling sheet; ③Shock and fall off caused by poor installation; ④Install in an inclined state.

2. Solutions

①Improve the installation and use methods; ②Prevent foreign matter from entering; ③If it is caused by metal sheets, check other parts.

Electric erosion

Resolve the phenomenon: the rolling surface has a pit-like pit, and the further development is in a wave plate shape.

1. Reason

The rolling surface is energized.

2. Solutions

Make a current bypass valve; take insulation measures to prevent current from passing through the inside of the bearing.

The above is the explanation of the common slewing bearing damage failure phenomenon, the reason analysis and the solution measures. I hope everyone will be helpful after reading it. Analyzing the damage and failure forms of the slewing bearing can provide a detailed reference for the design and selection of the bearing, and then improve the design, rationally select the bearing, give full play to the function of the bearing, increase economic benefits, and increase the service life.

What is the slewing ring gear module?

Slewing bearing is one of the important parts of many modern machinery and equipment. It is called “joint of machine”. Many people are familiar with various parameters of slewing bearing, including clearance, inner and outer diameter, friction coefficient, etc. Many friends don’t know the module of supporting gear. The technical staff of Longda Bearing, a slewing bearing manufacturer, will give us a detailed introduction to this problem.

1. What is the module of slewing ring gear

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

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

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

Slewing Bearings

2. Reasonable selection of gear module

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

Slewing Bearings

In the case of keeping the modulus unchanged, the diameter of the gear is proportional to the number of teeth, so the change of the number of teeth will also change the bending amount and elastic rigidity of the gear teeth: the strength of the noise generated by the sound source is not only related to the energy of the vibration source It is related to the size of the radiation area. If the radiation area is increased, the radiation power will also increase. Increasing the gear diameter will increase the noise radiation area, which will greatly affect the gear. Effective control of noise.

Therefore, in the relevant design, within the permissible range of ensuring the strength of the gear, the number of small teeth and the small modulus should be used as much as possible, and the reasonable selection of materials and heat treatment methods can be combined to promote the increase of the strength of the gear teeth, thereby reducing the diameter of the gear teeth. Then, the purpose of reducing gear noise is achieved.

What is the gear making process of slewing bearings

Gear processing is a time-consuming process in the production of slewing bearings, and it is also one of the main factors that have restricted the production efficiency of slewing bearings. Based on the actual machining data, the application of milling and hobbing processes in the processing of turntable bearing teeth is compared from the aspects of efficiency and cost, which provides a basis for the reasonable selection of turntable bearing teeth processing technology and equipment. Today, the editor will come to talk with you about the tooth-making process of slewing bearings.

1. Material selection of slewing bearing blank

Generally, 50Mn is used for the slewing bearing ring. After surface quenching, the raceway hardness is HRC55-62. However, sometimes 42CrMo is selected to meet the needs of the host for special applications, which has a higher hardness. LDB’s selection of blank suppliers has undergone strict screening and strictly follows the traceability procedure. For each blank, from receipt to finished product, it can trace the source of the blank according to its serial number, quality inspection and other whole-process data.

Slewing Bearings

2. The technology of making gears from slewing bearings

1. The equipment used in the gear processing department still uses a large number of ordinary gear hobbing machines and gear shaping machines. Although it is convenient to adjust and maintain, the production efficiency is low. If a large capacity is completed, multiple machines are required to produce at the same time. In order to solve the problem of low processing efficiency, while increasing the number of gear hobbing machines and gear shapers, high-speed gear milling machines are used, which has high processing efficiency and good surface finish quality.

2. Some slewing bearings used under severe conditions require surface quenching treatment, such as excavators, pile drivers, wood grabs, graders and other operating conditions, which have relatively large impact loads and require quenching treatment on the tooth surface. The hardness after quenching of several sizes is between 45-60HRC. For common working conditions such as cranes and tower cranes, the tooth surface does not need to be heat treated.

3. With the rapid development of Industry 4.0, slewing bearings are more and more widely used in the automation industry. In this application field, the accuracy requirements for the teeth are relatively high, and the low requirements are also 8 levels of accuracy. In response to the rapid changes in the market, during the construction of the new plant, higher accuracy requirements are required for the equipment to meet the market demand.

4. After the tooth-making process is completed, there are follow-up processes such as fine turning, plane, drilling, track grinding, and assembly, and the slewing bearing can be shipped out of the factory.

3. Introduction to the failure analysis of the slewing bearing gear

1. Improper adjustment of the backlash of the large and small gears during installation, which did not meet the requirements, resulting in poor meshing of the two gears during operation, resulting in broken teeth. The backlash should be adjusted strictly as required.

2. Failure to adjust the meshing gap with the pinion at the maximum position of the gear jump as required, causing the pinion to jam when meshing with the maximum gear jump position during operation, causing tooth breakage. The meshing adjustment should be carried out at the position painted with green paint and the pinion gear should be adjusted according to the requirements for trial operation.

3. The axes of the large and small gears are not parallel, and the large and small gears mesh poorly after installation, causing tooth breakage. It should be ensured that the axes of the two gears are parallel.

4. The mounting bolts are not fastened tightly, and the gears of large and small meshes are not well meshed, causing gear breakage. The bolts should be tightened as required.