What are the installation, maintenance and common problem solving of slewing bearings?
What are the installation, maintenance and common problem solving of slewing bearings?
Installation of turntable bearings:
Before installing the turntable bearing, the mounting surface of the host must be inspected. The supporting parts must have sufficient strength, the connecting surface must be machined, and the surface must be smooth and free of debris and burrs. For those that cannot be machined to achieve the required flatness, special plastics with high injection strength can be used as fillers to ensure the accuracy of the installation plane and to reduce vibration.
The ring of the slewing bearing has a quenched soft zone, which is marked "S" on the end face of the ring. When installing, the soft zone should be placed in the non-load zone or the non-frequent load zone (the plug hole is always located in the soft zone). belt).
When installing the slew bearing, you should first perform radial positioning, cross-tighten the mounting bolts, and check the rotation of the bearing. Sufficient pre-tightening force should be used when tightening bolts, and the pre-tightening force should be 70% of the yield limit of the bolt material. Mounting bolts should be equipped with quenched and tempered flat washers and spring washers are strictly prohibited.
Maintenance of turntable bearings:
After the slew bearing has been installed and put into operation for 100 hours of continuous operation, a comprehensive inspection should be made to see if the pretightening torque of the mounting bolts meets the requirements. The above inspection should be repeated every 500 hours of continuous operation.
After installation, the turntable bearing should be filled with an appropriate amount of grease, and the bearing should be rotated while filling to make the grease evenly distributed. After the slewing bearing has been working for a period of time, it will inevitably lose part of the grease. Therefore, the slewing bearing in normal operation should be replenished with grease every 50 to 100 hours.
Transportation and storage of turntable bearings
During transportation, the bearings should be placed horizontally on the vehicle. Measures should be taken to prevent sliding and vibration, and auxiliary supports should be added if necessary.
Reasons for failure during operation:
a. contact fatigue failure
Contact fatigue failure refers to the failure of the IKO bearing working surface due to alternating stress. Contact fatigue spalling occurs on the working surface of the slew bearing, and is often accompanied by fatigue cracks. It first occurs from the maximum alternating shear stress below the contact surface, and then expands to the surface to form different spalling shapes, such as pitting or pitting spalling. , peeling off into small flakes is called shallow peeling. Due to the gradual expansion of the peeling surface, it often extends to deep layers, forming deep peeling. Deep spalling is a fatigue source of contact fatigue failure.
b. Wear failure
Wear failure refers to the failure caused by the relative sliding friction between surfaces causing continuous wear of the metal on the working surface. Continuous wear will cause gradual damage to slew bearing parts, and eventually lead to loss of dimensional accuracy of IKO bearings and other related problems. Wear may affect shape changes, increase the fitting clearance, and change the topography of the working surface. It may affect the lubricant or contaminate it to a certain extent, causing the lubrication function to be completely lost, thus causing the bearing to lose rotational accuracy or even fail to operate normally. Wear failure is one of the common failure modes of various types of bearings. According to the wear form, it can usually be divided into the most common abrasive wear and adhesive wear.
Abrasive wear refers to the wear caused by the squeeze of foreign hard particles or hard foreign matter or wear debris on the metal surface between the working surfaces of IKO bearings and the relative movement of the contact surfaces. It often causes furrow-like scratches on the working surfaces of imported bearings. Hard particles or foreign matter may come from inside the host or from other adjacent parts of the host system and are sent into the turntable bearing by the lubricating medium. Adhesive wear refers to the uneven stress on the friction surface due to microscopic protrusions or foreign matter on the friction surface. When the lubrication conditions seriously deteriorate, local friction heat is generated, which can easily cause local deformation of the friction surface and friction micro-welding. Serious The surface metal may be partially melted, and the force on the contact surface will tear the local friction welding point from the matrix and increase the plastic deformation. This adhesion-tear-adhesion cycle constitutes adhesive wear. Generally speaking, slight adhesive wear is called abrasion, and severe adhesive wear is called occlusion.
c. fracture failure
The main reasons for bearing fracture failure are defects and overload. When the applied load exceeds the strength limit of the material and causes the part to break, it is called overload fracture. The main reason for overload is sudden host failure or improper installation. Defects such as micro-cracks, shrinkage cavities, bubbles, large foreign matter, overheated tissue, and local burns in IKO bearing parts can also cause fractures at the defects during impact overload or severe vibration, which is called defective fracture. It should be pointed out that during the manufacturing process of slew bearings, instruments can be used to correctly analyze whether the above-mentioned defects exist during incoming raw material re-inspection, forging and heat treatment quality control, and processing process control. Control must still be strengthened in the future. But generally speaking, most of the common IKO bearing fracture failures are overload failures.
d. Clearance change failure
When the slewing bearing is working, due to the influence of external or internal factors, the original fitting clearance changes, the accuracy decreases, and even causes "seizure", which is called clearance change failure. External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc., and internal factors such as retained austenite and residual stress in an unstable state are the main reasons for clearance change failure.
Contact
Company:Luoyang EFANT Precision Bearing Manufacturing Co. Ltd
Address:No. 9 Jingjin North Rd, Luoxin Development Zone,
Xin'an County, Luoyang City, Henan Province 471003, China
Tel:86-379-80887690
export@efindbearing.com
https://www.efindbearing.com/contact-us
https://www.efindbearing.com/slewing-bearing/dx340-excavator-slewing-bearing.html
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