Precautions and maintenance of slewing bearings on the reclaimer.
The reclaimer is a continuous and efficient bulk loading and unloading machine. It is widely used in raw materials fields of power plants, ports, steel plants, chemical plants, cement plants and other basic industries. It is suitable for strip or circular storage yards. Piles of bulk raw materials such as coal, iron ore, and limestone are taken continuously.
The slewing bearings of the reclaimer are most commonly used in the following three types: tapered roller slewing bearing, trolley type support, and rotary large bearing type support.
2. Slewing bearing type and structure type
2.1. Trolley type slewing bearing
The trolley type slewing bearing completes the turning motion by rolling the wheel along the circumference.
This type of support requires high assembly and machining accuracy. If it is slightly improper, the wheel rolling circle will not be perpendicular to the radius of gyration, and abnormal noise will occur.
When the slewing device is being repaired, it is necessary to use lifting equipment, large jacks, and necessary fixing and welding. The equipment needs to be disassembled locally, and many safety problems need to be dealt with.
Because of the relatively high height of the trolley itself, this type of support can easily increase the height of the center of gravity of the whole machine, which in turn affects the stability of the whole machine.
2.2. Rotary large bearing slewing bearing
There are many kinds of structural forms in this type of support. Among them, three rows of roller bearings are the most capable ones in various types. They have three races, and the upper and lower and the radial races are separated so that each row The load of the roller can be accurately determined, can withstand large axial forces, tipping moment and large radial force, and is especially suitable for heavy machinery such as reclaimer.
When the slewing device is being repaired, a large amount of work is required to replace the large bearing. It is necessary to use lifting equipment, large jacks, and necessary fixing and welding. The equipment needs to be disassembled locally, and many safety problems need to be dealt with. The maintenance cycle also takes about half a month. In terms of cost, if the large bearing is used as the slewing bearing, if the margin of choice is large, the bearing needs to be replaced in about ten years. The shortest in the country has five or six years to replace the large bearing equipment. The price of large bearings is relatively high, and the price of bearings of about 3 meters is more than 200,000 yuan.
The stacker and reclaimer is a large-scale mechanical equipment for open air operations. When using large rotating bearings, measures must be taken to prevent dust and water. It is very difficult to guarantee the above two. After the dust enters the water, it will increase the wear and corrosion of the bearing and reduce the service life of the bearing. In addition, large bearings should be placed horizontally during transportation and storage, and must be stored in a dry environment. The storage period should exceed a certain period of time, and other storage measures or anti-rust measures should be taken. Although the large bearing is simple to install, small in size and space saving, its cost is still relatively high.
2.3. Conical roller slewing bearing
After the support of the slewing roller, the cost is not much different from other support forms, but it has significant structural features:
2.3.1. No lubrication required: In actual operation, the roller and the bearing are almost unstressed due to the upper and lower pressure of the roller, and the load on the shaft and the bearing is only the additional load when the cage is fixed. Each roller bearing uses oil-impregnated bearings, so no lubrication is required.
2.3.2. Convenient maintenance: When using the conical roller support method, the maintenance is relatively simple and easy. It does not require large lifting equipment and jacks to complete, and the maintenance time is short, the maintenance cost is low, and it can be completed in one day.
2.3.3. The height of the center of gravity of the whole machine is low: because the diameter of the conical roller is relatively small, the overall height of the supporting device will be small, whether under normal working conditions or under high wind conditions, the supporting method is The stability of the machine will be better.
2.3.4. Low cost of spare parts: The conical roller type slewing bearing does not need to be replaced as a whole during maintenance. It only needs to be used with several rollers, and the spare parts cost is low.
2.3.5. Long service life: There are two reasons for the long service life of the tapered roller: First, the shaft and bearing of the tapered roller do not bear the supporting force of the slewing bearing, so that the bearing and the shaft have a long service life; the second is the diameter of the tapered roller. It is much larger than the diameter of the roller in the large bearing of the slewing bearing. Because of the large radius of curvature and the large number of tapered rollers, the contact stress of the tapered roller is small, so the large bearing has a relatively long service life.
2.3.6. Applicable to harsh environments: The stacker and reclaimer are large-scale mechanical equipment for open-air operation. The conical roller does not have to worry about dust and rain in specific use. Dust and rain do not have too much influence on the conical roller. The reason is that the diameter of the conical roller is much larger than the diameter of the roller of the large bearing, and the effect of a small amount of corrosion and dust on the conical roller and raceway is very small. The rollers and raceways should be properly greased during normal operation.
3. Summary
In the selection of the three slewing modes, in addition to the user’s designation, comprehensive aspects such as maintenance, installation, load capacity, space size, cost, machine stability, etc., the tapered roller slewing is preferred.
