Slewing bearing is also called rotary bearing. Some people also call it rotary bearing and slewing bearing. English Name: sliding bearing or sliding ring bearing or turntable bearing.

Chinese name slewing bearing foreign name slewing bearing also known as rotary table bearing introduction to the basic structure of new mechanical parts worm, slewing bearing, shell, motor, etc

brief introduction

Slewing ring is a new type of mechanical parts gradually emerging in the world in recent 40 years. It is composed of inner and outer rings, rolling elements, etc. the slewing ring produced in China is mainly the design and manufacturing technology of Rothe Erde company, the former federal country, which was organized and introduced by Tianjin Engineering Machinery Research Institute designated by the Ministry of machinery industry in the early 1980s. On December 20, 1984, the standard of the Ministry of machinery industry of the people's Republic of China: JB / 2300-84 slewing ring types, basic parameters and technical requirements was issued, which was mainly drafted by Tianjin Engineering Machinery Research Institute of the Ministry of machinery and electronics industry and Xuzhou Hailin slewing ring factory. Later, the state issued the standard of construction machinery: jb36 in 1991 1-36.3-91. New machinery industry standards JB / 2300-1999 and JB / 2300-2011 were issued successively in 1999 and 2011.

Slewing ring is a large bearing that can bear comprehensive load. It can bear large axial and radial load and overturning moment at the same time. Slewing bearing is generally equipped with installation hole, internal gear or external gear, lubricating oil hole and sealing device, so it can make the design structure of the host compact, simple guidance and easy maintenance. Slewing ring bearings are divided into four series: toothless, external and internal toothed four point contact ball bearings, double row angular contact ball bearings, cross cylindrical roller bearings, cross tapered roller bearings and three row cylindrical roller composite bearings. Among them, four point contact ball bearings have high static load capacity and cross cylindrical rollers have high dynamic load capacity, The pre interference of cross tapered roller bearing can make the bearing have greater support rigidity and rotation accuracy. Due to the improvement of bearing capacity, the three row cylindrical roller combined bearing leads to the bearing height, and various forces are borne by different raceways respectively. Therefore, under the same stress, the bearing diameter can be greatly reduced. Therefore, it is characterized by making the host more compact. It is a slewing bearing with high bearing capacity. Slewing bearing is widely used in large slewing devices of hoisting machinery, mining machinery, construction machinery, port machinery, ship machinery, high-precision radar machinery, missile launcher and other equipment. At the same time, we can also design, develop and produce various special structure slewing ring bearings according to the specific requirements of users.

Basic structure

Slewing drive is usually composed of worm, slewing bearing, shell, motor and other components. As the core component adopts slewing ring, it can bear axial force, radial force and overturning moment at the same time. There are many forms, but the structural composition is basically the same.

From left to right are (upper part):

1. Outer ring (toothed or toothless) 2 Sealing tape 3 Rolling element (ball or roller) 4 Fuel nozzle

From left to right are (lower part):

1. Blockage 2 Plug pin 3 Inner ring (toothed or toothless) 4 Spacer block or cage 5 Mounting hole (wire hole or smooth hole)

application

Slewing ring is widely used in real industry and is called "the joint of machine". It is mainly used in truck crane, railway crane, port crane, marine crane, metallurgical crane, container crane, excavator, filling machine, CT standing wave therapeutic instrument, navigator, radar antenna base, missile launcher, tank, robot, rotating restaurant and so on.

construction machinery

Slewing ring is widely used. Construction machinery is the first and most widely used place of slewing ring, such as earth moving machinery, excavator, disintegrator, stacker reclaimer, grader, roller, dynamic compactor, rock drilling machinery, roadheader, etc. Others include:

Concrete machinery: concrete pump truck, concrete mixing and distributing rod integrated machine, belt distributor

Feeding machinery: disc feeder and sand mixer

Hoisting machinery: wheeled crane, crawler crane, portal crane, tower crane, fork crane, traveling crane, gantry crane, foundation treatment machinery: impact reverse circulation drilling rig, rotary drilling rig, impact rotary drilling rig, rotary drilling rig, reverse circulation rotary drilling rig, positive circulation rotary drilling rig, long screw engineering drilling rig, submersible engineering drilling rig, static pressure pile driver and pile driver

Engineering vessel: dredger

Special vehicles: bridge inspection vehicle, fire truck, window cleaning machine, flat beam carrier, aerial work vehicle and self-propelled aerial work platform

Light industrial machinery: beverage machinery, bottle blowing machine, packaging machinery, filling machine, rotary bottle management machine and injection molding machine

Marine crane

Various equipment platforms

In addition to various construction machinery, the application scope of slewing ring has been gradually expanded. Similar port equipment, metallurgical equipment, drilling platform and other equipment platforms have begun to use slewing ring to replace the original bearing on a large scale.

Port equipment: port crane, front crane

New energy equipment: wind power generation equipment, solar power generation equipment

Metallurgical equipment: metallurgical crane, ladle turret, steel grabbing machine, mud gun and oxygen blowing device

Amusement equipment: Ferris wheel, etc

Airport equipment: Airport tanker

Military equipment: radar, tank, etc

Robot: palletizing robot, welding robot, manipulator

Medical equipment: Gamma Knife

Environmental protection equipment: mud scraper

Parking equipment: tower garage

Drilling platform equipment, kitchenware equipment, CNC equipment (wire cutting machine, quenching machine tool), brick machine

Common materials

Materials for ferrule and rolling element

Generally, the rolling element of slewing ring adopts integrally hardened carbon chromium bearing steel. Made of GCr15 or GCr15SiMn steel; The slewing ring ferrule is made of surface hardened steel. When the user has no special requirements, it is generally made of 50Mn steel. However, sometimes, in order to meet the needs of the host in some special applications, other brands of surface hardened steel can also be selected according to the specific service conditions provided by the user, such as 42CrMo, 5CrMnMo, etc.

Material for cage

The cage for slewing bearing has integral type, sectional type, isolation block type and other structural forms. The integral and segmented cages are made of 20 steel or ZL102 cast aluminum alloy. The isolation block type is made of Polyamide 1010 resin and ZL102 cast aluminum alloy. In recent years, with the continuous development of material industry, nylon grpa66 25 can also be popularized and applied in the design of segmented cage.

Material for sealing ring

The material used for the sealing ring of slewing ring is made of oil resistant butadiene rubber.

The code of ferrule material and blank supply state shall be in accordance with the provisions of the table. In the table, "t" indicates that the ferrule blank is supplied in the quenched and tempered state, and "Z" indicates that the ferrule blank is supplied in the normalized state.

The central circle diameter of the rolling element is 3150mm, the ball diameter is 75mm, the gear module is m = 20mm, the ring material is 50Mn, and the blank material is normalized. The internal gear type four point contact ball slewing bearing is 013.75.3150.12 [1].

type

Three row combined roller slewing bearing

The three row roller slewing ring has three seat rings, and the upper and lower and radial raceways are separated respectively, so that the load of each row of rollers can be determined accurately and can bear various loads at the same time. It is the one with the largest bearing capacity among the four products. The shaft and radial dimensions are large and the structure is firm. It is especially suitable for heavy machinery requiring large diameter, such as bucket wheel excavator, wheel crane, marine crane Ladle slewing and large tonnage truck crane and other machinery.

Double row angular contact ball slewing bearing

The double volleyball slewing ring has three seat rings. The steel balls and isolation blocks can be directly discharged into the upper and lower raceways. According to the stress condition, the upper and lower rows of steel balls with different diameters are arranged.

This kind of open assembly is very convenient. The bearing angle of the upper and lower arc raceways is 90 °, which can bear great axial force and overturning moment. When the radial force is greater than 0.1 times the axial force, the raceway must be specially designed. The axial and radial dimensions of double volleyball slewing ring are relatively large and the structure is firm. It is especially suitable for tower cranes, truck cranes and other loading and unloading machinery requiring medium or above diameter.

Single row cross roller slewing bearing

The single row cross roller slewing bearing is composed of two seat rings, with compact structure, light weight, high manufacturing accuracy, small assembly clearance and high requirements for installation accuracy. The rollers are arranged in a 1:1 cross arrangement, which can bear axial force, large radial force and overturning moment at the same time. It is widely used in lifting and transportation, engineering machinery and military products.

Single row four point contact ball slewing bearing

The slewing bearing of single row four point contact ball bearing is composed of two races, which has compact structure and light weight. The steel ball is in four point contact with the circular arc raceway, and can bear axial force, radial force and overturning moment at the same time. Small and medium-sized engineering machinery such as excavator and rotary crane can be used for operation.

resolvent

There are two common solutions to the noise of slewing ring, i.e. dust sound and scar sound, as follows:

(1) Control method of dust sound

There are dust and other foreign matters in the rotary support, which will produce aperiodic vibration. The so-called dust sound, the magnitude of vibration and noise is uncertain, with or without.

Control method of dust noise: improve the cleaning method of slewing ring / rotary table bearing, and strictly clean the bearing, shaft, seat hole and matching parts before installation; Remove foreign matters in the lubricant; Improve the sealing of bearings; Avoid using plastic cages with impure materials or embedded foreign matters.

(2) Control method of scar sound

If there is crack, indentation or corrosion on the rolling surface of the slewing ring, periodic vibration and noise like riveting rivets will occur. The cycle may be fixed, but most of them have a certain corresponding relationship with the rotating speed. The scars will occur continuously on the channel, and the scars will appear on the steel ball from time to time, and this noise will change with the installation and lubrication conditions.

Control method of this kind of noise: do not knock the bearing during installation. When the bearing is assembled with the shaft and then installed into the bearing seat, prevent the bearing from being installed obliquely; Prevent bearing corrosion during storage and impact vibration during transportation; Use grease with high viscosity.

(3) Noise caused by lubrication factors and Its Countermeasures

Incorrect lubricant selection, insufficient lubricant or aging and hardening can lead to vibration and noise of slewing ring / rotary table bearing, and this noise has no certain law. In this case, only the appropriate lubricant can be selected, the lubricant amount can be adjusted, the service life of the lubricant can be prolonged and the replacement cycle can be reasonably determined.

(4) Noise and Its Countermeasures

This kind of noise is not simply caused by the bearing, so it is invalid to find the reason only from the bearing. We should pay full attention to the main engine and improve the performance of the main engine if necessary. This paper mainly describes the common buzzer sound and frame resonance sound in the motor.

Buzzer of a motor and Its Countermeasures

The axial vibration of the motor shaft will cause great high-frequency noise - buzzer. Its frequency is the same as the axial vibration frequency, which can be constant or variable. The method to prevent the buzzer is the same as that to prevent the axial vibration.

Resonance sound of B bearing frame and Its Countermeasures

When the axial bending natural vibration of the bearing frame is caused by the axial natural vibration of the outer ring mass system, a noise called resonant sound will be generated. The method of pre tightening can improve the axial natural frequency of the outer ring mass system, destroy the resonance condition and reduce the noise.