Tunnel Boring Slewing Bearing

Tunnel Boring Slewing Bearing

Driving reliability to cut tunnel completion times, slewing bearings for tunnel boring machines are built to withstand huge loads as cutter heads bore into solid rock or dificult soils. These heavy-duty, roller bearings are designed  to carry all cutter head loads and transfer  them to the rear. In addition, we use our sealing expertise to integrate proven designs for tunnel boring machine head applications that keep earth out of the main bearing and lubricants in it.

We offer solutions for a broad array of applications based on our wide variety of experience in major tunnel projects worldwide including.

“has the best bearing cages and was able to ind logistics solutions to meet our expectations in a very short time.”– Tunnel boring customer.

Slewing Driver Application

Slewing bearing comes in many sizes

Slewing Ring Bearings in Construction and Excavator and Roller Applications

Slewing Ring Bearings in Construction and Excavator and Roller Applications

LDB slewing bearings of the preloaded,cross-roller type are an ideal choice for excavators as they offer high reliability even when subject to heavy loads and tilting moments in severe operating

environments.

LDB also works closely with road roller to provide customised slewing bearing solutions designed to handle the high vibration levels needed for highspeed,high-quality compacting. Due to an integrated, reinforced sealing system,the bearings remain unaffected by the hot asphalt environment and are protected against water intrusion.

Is the surface roughness of the slewing bearing as small as possible? How to choose?

Is the surface roughness of the slewing bearing as small as possible? Surface roughness refers to the small spacing and the unevenness of small peaks and valleys that the machined surface has. The roughness of the bearing surface may affect the wear resistance, stability, fatigue strength, stability and other properties of the bearing. Generally speaking, the smaller the roughness of the bearing surface, the better, but it should be determined according to the equipment use requirements and process accuracy.

The surface roughness of the slewing bearing is not as small as possible

Slewing Bearings

Is the surface roughness of the slewing bearing as small as possible? It can be analyzed from the following aspects:

1. Physical properties of materials

The surface roughness of the bearing is often represented by Ra. Generally speaking, from the working principle, we hope that the smaller the surface roughness of the slewing bearing, the better. Generally, the higher the bearing tolerance accuracy level, the better the surface quality and the finer the workmanship. However, two surfaces that are too smooth are prone to gluing (exchange between the same or similar materials, which is similar to the “dyeing phenomenon” in our life, but it belongs to the exchange of metal substances here), while the surfaces that are too rough are prone to gluing. Under the action of force, the surface is prone to peeling off (that is, what we often call wear).

2. Processing cost

Theoretically, the smaller the value of the surface roughness of the slewing bearing, the better, the smaller the roughness, the smoother the surface and the more beautiful the appearance. However, the size of the roughness is determined by the machining process and other factors, such as the friction between the tool and the bearing surface, cutting, and high-frequency vibration in the process.

However, the smaller the surface roughness, the higher the processing cost. Whether the use cost of the part matches the consumption speed and the profit of the equipment production output value. These all need to be considered. Some spare parts do not have high requirements on the roughness of the bearing surface. Excessive pursuit of the surface roughness will affect the economy of processing.

Selection principle of surface roughness of slewing bearing

slewing bearing

1. Economic perspective:

From an economic point of view, on the basis of meeting the performance requirements of the slewing bearing, the lower the accuracy, the better. This allows for lower production costs.

2. Use function:

(1) The roughness value of the working surface is smaller than that of the non-working surface.

(2) The roughness value of the friction surface is smaller than that of the non-friction surface.

(3) The roughness value of the clearance fit is smaller than that of the interference fit.

(4) The roughness of the mating surface should be equivalent to its dimensional accuracy requirements. The smaller the size, the smaller the roughness value should be.

(5) The roughness value of the surface subjected to cyclic load and the inner fillet and concave part where stress concentration may occur should be small.

Is the surface roughness of the slewing bearing as small as possible? I believe everyone is clear. The actual selection of bearing accuracy and surface roughness needs to be determined according to actual needs. In the case of ensuring bearing performance, cost control is also very important.

Slewing Bearing Comes In Many Sizes

Slewing bearing comes in many sizes

LDB Slewing Bearing Manufacturer custom designed and manufactured a segmented, 3-row roller bearing almost 14 m in diameter. It weighed 70 tons.LDB Slewing Bearing Manufacturer also produces a range of smaller slewing bearings for special machinery,high-tech applications and more.

For more than a half century, LDB Slewing Bearing Manufacturer has been designing and manufacturing many types and sizes of high-performance slewing bearings to meet the speciic needs of customers worldwide. Combining decades of application knowledge and unmatched manufacturing expertise, LDB Slewing Bearing Manufacturer provides customised slewing bearings with outer diameters from 0,1 m to 14 m.

Unlike other providers of slewing bearings, LDB Slewing Bearing Manufacturer can offer fully tailored slewing bearing solutions with integrated advanced monitoring, lubrication and sealing systems for higher reliability and longer service life. Our breadth of engineering knowledge, global presence and design lexibility allow us to deliver the right solution for your project, no matter how large or complex.

High-performance slewing bearings

For a wide range of applications:

  • Wind turbines
  • Tunnel boring machines
  • Excavators
  • Forestry vehicles
  • Rail vehicles
  • Dockside and deck cranes
  • Mobile cranes
  • Water treatment equipment
  • Bottle illing systems
  • Metals
  • Material handling
  • Marine pods
  • Offshore buoys
  • Stacker reclaimers

Model parameters of externally toothed three-row cylindrical roller slewing bearings

Slewing bearing design types:

  • Double row ball bearings
  • 4point

Contact bearings

  • Crossed roller bearings
  • Wire race bearings
  • 3row

and double row cylindrical roller bearings

  • Cylindrical roller and ball bearings
  • Special bearings

Slewing Driver Application

Slewing reducer -Slewing driver can be applied to the host of the circular motion, such as the crane rotation platform and the rotation machinery, etc. The turbine and worm mechanisms are often used for two -axis intertwined, large transmission ratio, small transmission power, or intermittent work. This product can be widely used in the field of engineering machinery represented by high -altitude operating vehicles, car cranes, new energy fields represented by solar photovoltaic power generation, wind power generation, and other fields of automation, machine tool manufacturing, aerospace communications and other fields. Therefore, the product’s market potential is huge.

Slewing drive
Slewing reducer –Slewing driver Subjective list

Rotate machine with a dual snail turn drive drive

Driver driver with a car

Heavy tablet transport vehicle turning driver

High -altitude operating vehicle turning driver

Railway turning driver Driven driver

Slewing claws with rotation driver

Bridge detection vehicle rotation driver device

China Railway Liangji Slewing Driver Device

Solar turning driver

How is the slewing bearing soft belt produced? The installation position of the flexible belt

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 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, 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.

Slewing Bearings

The heated flame spray gun and water gun are mounted together while making 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.
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Under normal circumstances, the steel character “S” is marked on the position where the soft belt exists in the workpiece to indicate the specific 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.

2. The installation position of the soft belt

Slewing Bearings

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.
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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, so as 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.

What are the sealing methods of the slewing bearing? Sealing function and method

We know that the slewing bearing has a very important role in some production, and in order to ensure these functions, we need to perform a lot of operations on the slewing bearing during the use of the slewing bearing. The sealing of the more common bearings, then why should the slewing bearing be used? to seal? What are the common sealing methods of slewing bearings?

The role of sealed slewing bearing

Slewing Bearings

1. Isolate foreign objects from outside

Protect the bearing to prevent external dust, dirt, metal particles, moisture, acid gas and other debris from invading the inside of the bearing. If the bearing is poorly sealed and external debris invades, the working condition of the bearing will be significantly deteriorated, and the service life of the bearing will be significantly reduced.

2. Prevent grease leakage

If the oil leaks, it will quickly destroy the normal lubrication of the bearing, causing the bearing to burn out due to heat. In addition, the poor sealing device not only causes waste of oil leakage, but also contaminates mechanical equipment and processed products. Therefore, to make the machine work properly, the bearing must have a good sealing device.

The way of sealing the slewing bearing

Slewing Bearings

Generally, the sealing methods of bearings include contact sealing and non-contact sealing, but these two sealing methods are suitable for different situations. Contact sealing is suitable for bearings operating in medium and low-speed working environments, while non-contact sealing Bearings that are suitable for high-speed and high-temperature working environments, as slewing bearings, generally operate at low speeds, but there are also high-temperature operations. The analysis shows that the methods of sealing slewing bearings are as follows:

1. Felt ring seal

A trapezoidal groove is opened on the bearing cover, and the fine felt on the rectangular surface is placed in the trapezoidal groove to contact the shaft, or the gland is pressed axially, so that the felt ring is compressed to generate radial pressure and hug the shaft, thereby achieve the purpose of sealing. The sealing structure is simple and the cost is low, but the sealing effect is poor, it cannot be adjusted, and the wear is serious.

2. The leather bowl is sealed

Place a sealing cup in the bearing cover (the cup is made of rubber and other materials) and press it directly on the shaft. In order to enhance the sealing effect, a ring-shaped coil spring is used to press the inner ring of the leather cup, so that the inner ring of the leather cup and the shaft have a tighter fit, and the sealing effect is better than that of the felt ring. /s of grease lubrication or lubricating oil lubrication.

3. Sealing ring seal

The sealing ring is usually made of leather, plastic or oil-resistant rubber, and can be made into different cross-sectional forms as required. The 0-shaped sealing ring has a circular section and is pressed on the shaft by its own elastic force. It has a simple structure and is easy to assemble and disassemble. Also commonly used are J-shaped and U-shaped profile seals, which all have a lip-shaped structure. The direction of the sealing lip is towards the sealing part, which is similar to the direction of the flange in the cup seal. When the temperature is high and the rotational speed is high, it is recommended that the sealing lip also be installed away from the bearing. The sealing effect of the sealing ring is better than that of the felt ring, and it can be used for the sealing of grease and oil.

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4. Skeleton seal

The skeleton seal we often say is the improvement of the leather cup seal. In order to improve the overall strength of the leather cup seal, a metal lining with an L-shaped cross-section and an overall annular shape is installed in the oil-resistant rubber, so that the leather cup seal is not easily deformed and improves the use of This kind of seal is easy to install and has good performance. It is generally suitable for occasions where the peripheral speed of the journal is 7m/s.

5. Sealing ring seal

This is an annular seal with a gap, which is placed in the ring groove of the sleeve, the sleeve rotates with the shaft, and the seal ring is pressed against the static part by the elasticity of the gap after being compressed. On the inner hole wall, it can play a sealing role, and this kind of sealing is more complicated.

6. Labyrinth seal

The basic principle of this kind of seal is to form a section of flow channel with great flow resistance at the seal. Structurally, a small tortuous gap is formed between the stationary part and the rotating part, forming a “labyrinth”. If the “labyrinth” is radial, the axial dimension is compact, but the radial dimension is larger. If the “labyrinth” is axial, the radial dimension is compact, but the bearing cover should be divided, and the axial clearance should be larger, so as not to be stuck due to thermal deformation of the shaft. Labyrinth seals are quite reliable for both lubricating oil and bone grease, and the higher the speed, the better the effect.

The above is the summary of the sealing methods of the slewing bearing, and the whole content of the sealing function and method. We have learned that the slewing bearing has the functions of isolating foreign objects and preventing grease leakage. The common methods are felt ring sealing, leather cup Seal, seal ring seal, skeleton seal, seal ring seal, labyrinth seal, etc., you can choose according to the specific situation of your bearing

What are the classifications of slewing bearings? How to choose a model?

There are many classifications of slewing bearings, each type has different characteristics, and the scenarios used are also different. You may not be very clear about the selection type. Generally, the selection type should be considered: slewing accuracy, bearing capacity, working temperature, In terms of running speed, etc., let’s take a look at the specific method with the slewing bearing manufacturer~

Classification of slewing bearings

Four Point Contact Ball Slewing Bearing

1. Three-row combined roller slewing bearing

The three-row roller slewing bearing has the upper and lower and radial raceways of the three races separated, so that the load of each row of rollers can be accurately determined. It can bear various loads at the same time, has a firm structure, and has large shaft and radial dimensions. It is suitable for heavy machinery requiring large diameters.

2. Double row angular contact ball slewing bearing

The double-row ball slewing bearing has three races, and the steel balls and spacers can be directly discharged into the upper and lower raceways. According to the stress conditions, two rows of steel balls with different diameters are arranged. The axial and radial dimensions of the double-row ball slewing bearing are relatively large, and the structure is firm, especially suitable for machinery that requires a medium or larger diameter.

3. Single row cross roller slewing bearing

The single-row cross-roller slewing bearing is composed of two races, with compact structure, high manufacturing precision, light weight, small assembly clearance, and can bear axial force, large radial force and tipping moment at the same time.

4. Single row four-point contact ball slewing bearing

The single-row four-point contact ball bearing slewing bearing is composed of two races, with compact structure, light weight, four-point contact between the steel ball and the arc raceway, and can bear axial force, radial force and tipping moment at the same time.

Factors to consider when choosing a slewing ring bearing type

Double Row Different Diameter Ball Slewing Bearing

1. Carrying capacity

The bearing capacity is one of the factors that determines the size of the bearing. In general, the four-point contact ball slewing bearing can withstand heavier radial loads, so it may be more suitable for the occasions where the heavier load and the size and direction of the load may change The four-point contact is a slewing bearing.

2. Rotation accuracy

If the bearing positioning capability is required to be high, the crossed roller slewing bearing can be selected.

3. Working temperature

In general, the operating temperature of the slewing ring bearing mainly depends on the sealing material, grease, isolation block, and the operating temperature range is -25 to +70 °C.

4. Running speed

The four-point contact ball slewing ring bearing has a high limit speed, and the friction force generated is smaller than that of the cylindrical roller slewing ring.

5. Sealing conditions

Qualified seals used in slewing bearings can provide good moisture and pollution protection, and ensure sufficient quality in the bearing, which can prolong the service life of the bearing, so the seal is very important for the performance of the slewing bearing.

6. Vibration

For vibration applications, both four-point contact ball slewing rings and crossed cylindrical roller slewing rings are suitable.

The above article describes the classification of slewing ring bearings in detail, and the factors that need to be considered when choosing the type. I hope it can help you. If you have other questions about slewing ring bearings, you can leave us a message~

What are the application fields of slewing drive

The slewing drive can be applied to the main engine that does circular motion, such as crane turntable, rotating machinery, and other machines that perform circular work.

Slewing drive can be widely used in the field of construction machinery represented by aerial work vehicles and truck cranes, as well as in the field of new energy represented by solar photovoltaic power generation and wind power generation, as well as other fields of automation, machine tool manufacturing, aerospace communications, etc. It can be said that this product The market potential is huge.

1. The field of beam transport vehicles

The core components of the traditional beam-carrying slewing assembly mostly use traditional slewing bearing products. Since the slewing bearing does not have an outer casing, the corrosion resistance is not ideal. For the steering system that relies on hydraulic cylinders to push the tires, the The range of rotation angles is also greatly limited.

VE Series Slewing Drive

2. Field of aerial work vehicles

Aerial work vehicles are an important application area of ​​slewing drive. Usually, aerial work vehicles require the main engine to have a high safety factor. The high safety of slewing drive (self-locking of worm gears) is the choice of the majority of users as accessories for aerial work platforms. An important factor; on the other hand, the worm gear transmission has a larger transmission speed ratio, which improves the safety factor of the main engine and also omits a set of worm gear reducers for the main engine, thereby reducing the manufacturing cost of the main engine.

3. Photovoltaic power generation field

Photovoltaic power generation is an important application field of rotary drive. The use of solar photovoltaic modules with rotary drive as a rotating component can accurately adjust the rotation angle and elevation angle of the host according to the different positions of the sun during the day. the receiving angle.

SE Series Slewing Drive

4. Wind power generation

Similar to the photovoltaic discovery, the slewing drive can be applied to the yaw part of the wind turbine to realize the horizontal 360 rotation of the mechanism, so as to better adjust the receiving angle.

5. The field of construction machinery claws

Auxiliary equipment for construction machinery is a brand-new application field of slewing drive.

The above is all about the application field of slewing drive. If you have any questions during use, please feel free to communicate with us in depth.

What are the common load forms of slewing bearings?

We all know that no matter what the bearing is, it will bear a certain load, and the slewing bearing is no exception. So, what is the load of the slewing bearing? What are the common load forms of slewing bearings? Today, the editor will introduce to you the common load forms of slewing bearings, hoping to help you understand more about slewing bearings.

1. What is the slewing bearing load?

It is only said that the load refers to the external force and other factors that cause the internal force and deformation of the structure or component, and the load of the bearing refers to the limit force that the bearing can bear under the action of the internal force and external force. The load is also called the load, which is used as a slewing bearing. Said that the types of loads it can bear include traditional radial and bearing loads, working loads, temperature loads, etc. The following editor will introduce these loads to you respectively.

2. Common load forms of slewing bearings

Slewing Bearings

(1) Radial and axial loads

In a rolling bearing, when the total plastic deformation is less than one ten thousandth of the diameter of the rolling element at the contact point between the rolling element and the raceway that bears a relatively large load, it has little effect on the normal operation of the bearing.

The static load capacity of the bearing determined under this plastic deformation condition is called the rated static load. The rated static load is determined under the assumed load conditions. For radial bearings, the rated static load refers to the radial load, and the radial load Thrust bearing (angular contact ball bearing) refers to the radial component of the load that loads the half-ring raceway in the bearing, and for a thrust bearing, it refers to the central axial load. The basic static load rating and basic static load rating of the bearing refer to the maximum load that the bearing can bear when it is static or rotating.

(2) Working load

The working load means that the slewing bearing device bears the weight of the machine itself and the weight of the increased weight during work, and then slowly transfers the total weight to the slewing bearing device. Ensure that the slewing bearing device has a steady stream of power and operates normally.

(3) Temperature load

When the mechanical equipment is working, it will generate a certain temperature, and all these temperatures must be absorbed by the slewing bearing device, so that the slewing bearing can withstand all the temperatures. The force of the slewing bearing against temperature is what we call the temperature load.

(4) Wind load

When the machine works in the open air, it is necessary to consider the effect of wind load, including wind direction, rain, thunderstorm weather and so on. The above is only a part of the load that the slewing bearing device bears. In fact, the slewing bearing device needs to bear more load in order to meet all the weight and load of the machine in work. Under normal circumstances, the slewing bearing itself is equipped with mounting holes, lubricating oil and sealing devices, which can meet the different needs of various types of hosts working under various working conditions.

slewing bearings

(5) Risk load

That is, the unexpected and unpredictable loads, cross forces, risk forces, unexpected violence, etc. that the slewing bearings and slewing bearings bear. Therefore, the selection of the slewing bearing will have the existence of a safety factor to ensure foolproof.

(6) Dynamic load

Dynamic loads include inertial loads, vibration loads and shock loads. The mass force caused by the change in the magnitude and direction of the movement speed becomes the inertial force. These are all part of the dynamic load.

(7) Static load

The load capacity of the bearing at rest is determined by the allowable amount of plastic deformation. Plastic deformation in rolling bearings is unavoidable. If the allowable amount of plastic deformation is limited, the static load capacity of the bearing is also small; if the allowable plastic deformation is large, the pits generated on the raceway will increase the noise and vibration of the bearing during operation, and improve the running accuracy. Reduced, affecting the normal operation of the bearing.

The above is what the common load forms of slewing bearings are summarized by Xiaobian for you, and all the types of loads that slewing bearings can withstand. We understand that the common load types of slewing bearings include traditional radial load and axial load, working load , temperature load, wind load, risk load, dynamic load, static load, etc. Because of the existence of these loads, the slewing bearing can operate safely and ensure the normal operation of the equipment.