What should I pay attention to in the installation and maintenance of four-point contact ball slewing rings?

What is four-point contact ball slewing ring

The four-point contact ball slewing ring is composed of the inner ring, the outer ring, the steel ball and the retaining frame, the inner and outer rings are provided with arc-shaped raceways, and the steel ball and the raceway form a four-point contact slewing part, this unique structure makes it able to bear axial force, radial force and overturning moment at the same time, the contact stress is evenly distributed, the bearing capacity is high and the rigidity is good; When working, the steel ball is rolled in the raceway to achieve relative rotation of the inner and outer rings, which can ensure the smooth and accurate movement, and is widely used in cranes, excavators, wind turbines, automatic production line rotary workbenches and other equipment that needs to rotate and has requirements for bearing and accuracy.

Features of four-point contact ball slewing rings

High bearing capacity: The unique four-point contact structure makes the steel ball have four contact points with the inner and outer ring raceways, which can withstand axial force, radial force and overturning moment at the same time, and can adapt to complex stress conditions with high bearing capacity.

Good rotation accuracy: the steel ball rolls in the raceway, the movement is stable, and the uniformity of the four-point contact helps to ensure the accuracy of the rotary movement, which can meet the application scenarios with high requirements for rotary positioning accuracy.

Compact structure: Compared with some other types of slewing rings, under the same bearing capacity, the structure of four-point contact ball slewing rings is relatively compact, and the space occupied is small, which is conducive to the miniaturization design of equipment.

Easy installation: its structure is relatively simple, the installation process is relatively convenient, and there are usually mounting holes on the inner and outer rings, which are convenient for connection and fixation with other parts of the equipment, which can effectively improve the installation efficiency.

Low maintenance cost: rolling friction is adopted, the friction coefficient is small, the wear is relatively small, and it is generally equipped with a good sealing and lubrication system, which can effectively reduce the intrusion of external impurities and the wear of components, thereby reducing maintenance costs and prolonging service life.

Strong adaptability: According to different work requirements, by changing the material, surface treatment process and structural parameters, etc., to meet the needs of various harsh working environments and special working conditions, such as high temperature, low temperature, high humidity, corrosive environment, etc.

What should I pay attention to in the installation and maintenance of four-point contact ball slewing rings?

The installation and maintenance of four-point contact ball slewing rings need to pay attention to the following aspects:

Installation precautions

Check before installation

Check whether the model and specification of the slewing ring are consistent with the design requirements, whether there are defects and damage in the appearance, and whether the parts are complete.

Measure the main dimensions of the slewing ring, such as outer diameter, inner diameter, width, etc., to ensure that the dimensional deviation is within the allowable range. At the same time, check the surface quality of the raceway and rolling elements, and there should be no cracks, pitting, scratches and other defects.

Check the flatness, verticality and roughness of the mounting surface, the installation surface is required to be smooth and clean, the flatness error is generally not more than 0.05 - 0.1mm/m², and the roughness Ra value is between 6.3 - 12.5μm.

Installation process

Slewing rings should be installed in a clean, dry environment and avoid installation in dusty, oily or wet places. When installing, special installation tools, such as hoisting equipment, bolt tightening tools, etc., should be used to ensure that the installation process is standardized and safe.

The connecting bolts are tightened step by step in a symmetrical and crossed manner, and the bolts are tightened evenly to the specified torque value in multiple times. Generally, it is tightened to 50% - 60% of the specified torque for the first time, then tightened again to 80% - 90%, and finally the specified torque is reached. This ensures that the slewing ring is installed evenly and the force is balanced.

During the installation process, attention should be paid to avoid the slewing ring being subjected to impact, collision or excessive external force, so as to prevent damage to the raceway and rolling elements. At the same time, ensure that the installation position of the slewing ring is accurate, and the mating clearance with adjacent components meets the design requirements.

Check after installation

After the installation is completed, check the installation accuracy of the slewing ring, including radial runout, end face runout, etc., and its value should meet the requirements of the corresponding accuracy level. Generally, the slewing ring with P0 accuracy should not exceed 0.1 - 0.2mm in radial runout and 0.05 - 0.1mm in the end face.

Manually rotate the slewing ring to check whether its rotation is flexible, and whether there are abnormal phenomena such as stagnation and abnormal noise. If there is an abnormality, the cause should be found in time and adjusted or repaired.

Maintenance precautions

Lubrication management

Choose the right lubricant and choose the appropriate grease or oil according to the operating conditions of the slewing ring (e.g. temperature, load, speed, etc.). Generally speaking, high-temperature resistant greases can be used in high-temperature environments, such as complex lithium-based grease; In the case of high-speed operation, a low-viscosity lubricant can be considered.

Replenish and change the lubricant regularly, and the first grease replenishment should be made after 100 to 200 hours of operation for the first slewing ring, and every 500 to 1000 hours thereafter. Depending on the use of the lubricant and the working environment, the grease or oil should generally be replaced every 6-12 months.

When lubricating, ensure that the lubricant is evenly distributed on the surface of the raceway and rolling elements. Lubricant can be injected into the slewing ring through the grease nipple or oil cup, while care is taken to drain out old lubricants and impurities.

Seal maintenance

Regularly check the status of the sealing device, such as whether the sealing lip is worn and aged, and whether the seal is cracked or deformed. If there is damage, the seal should be replaced in time to prevent lubricant leakage and external impurities from entering the slewing ring.

Keep the sealing part clean to prevent dust and oil from accumulating in the sealing place and affecting the sealing effect. When cleaning, use a soft cloth or brush to avoid damaging the surface of the seal.

Regular inspection and maintenance

Regularly check whether the connecting bolts of the slewing ring are loose, and if they are loose, they should be tightened in time. At the same time, check the wear of the bolts, if there is serious wear or damage, the bolts should be replaced in time.

At regular intervals (e.g. 3 to 6 months), a comprehensive inspection of the slewing ring is carried out, including the wear of the raceway and rolling elements, changes in slewing accuracy, and whether there is any abnormal noise. Through inspection, potential problems can be found in time, and corresponding measures can be taken to repair or replace them to ensure the normal operation of the slewing ring.

During the installation and maintenance of four-point contact ball slewing rings, operators should operate in strict accordance with relevant standards and specifications to ensure the performance and service life of slewing rings.

Four-point contact ball slewing ring supplier

As a well-known supplier of slewing bearings with 30 years’ experience, LTZC bearings is committed to providing slewing bearings with high quality and low price. The specific price needs to be comprehensively evaluated according to the size, load, material and accuracy requirements of the bearings. Please contact us if necessary.