2022 November the Four Week VISTA Technical Knowledge: Application of Workpiece Fixture in Installation of Large Spherical Roller Bearing

Hot tags: spherical roller bearing(7)

Abstract: This paper describes the difficulties encountered in the installation of large self-aligning roller bearings, analyzes the causes, and puts forward solutions and installation methods.

Key words: Fixture; Bearing installation; application

 

In order to meet the needs of mine reconstruction and expansion, Longshou Mine of Jinchuan Company in Gansu Province has carried out technical transformation on the underground ore crushing and transportation system. The total cost of the project is 2.812 million yuan, mainly including the installation of shaft cage way and ladder room, blind shaft elevator, metering hopper, belt lane equipment and crusher chamber equipment. The second engineering plant of China Coal Fifth Company won the bid at one stroke. In the whole project, the equipment installation of the crushing chamber is an important link of the technical transformation system project under the mine, and is the main line that affects the progress of the whole project. The chamber is designed and installed with vibrating ore drawing machine, vibrating feeder and jaw crusher. Jaw crusher is the main equipment, with large size, heavy weight and overall dimension (long × Width × Height) is 6,976 × 2,650 × 1932.5mm, weighing 33.4t. According to the site conditions, the crusher is disassembled on the ground into three main components: static jaw, movable jaw and base, and then transported to the crushing chamber for assembly, installation and commissioning underground.


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1. Problem posing

The assembly of jaw parts of crusher is the key link of the whole crusher assembly. The moving jaw components are disassembled into jaw plate assembly, eccentric shaft, flywheel, sheave, roller self-aligning bearing and other parts during lowering and transportation. The workload and difficulties of moving jaw assembly mainly focus on the installation of eccentric shaft. The assembly drawing of eccentric shaft is shown in Fig. 1.

 

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1. Eccentric shaft; 2. Bolts; 3. Moving jaw; 4. Bearing Figure 1 Assembly Drawing of Eccentric Shaft

 

The movable jaw weighs 7267.2kg, and the aperture is 580mm; The eccentric shaft is 2554mm in length, 18.5mm in eccentricity and 1396.3kg in weight; The model of roller self-aligning bearing is 3003264, and the weight is 259kg. The large volume and heavy weight of the assembly parts make the installation very difficult. A 10t electric hoist is installed in the chamber for maintenance and repair when the equipment is put into operation. During installation, electric hoists are used to transport large parts to assist installation. Due to the limitation of the installation height of the electric hoist, the eccentric shaft and movable jaw hole cannot be vertically hoisted during installation, so the idea of using the dead weight of the eccentric shaft to add force to assemble cylindrical roller self-aligning bearings cannot be implemented. During installation, the round hole end of the movable jaw shall be padded up and inclined to ensure the extended length space of the shaft when it is installed in place, as shown in Figure 2.

 

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Fig. 2 Eccentric shaft installation method I

 

During the installation, it was found that the hole end of the eccentric shaft was inclined, resulting in new situations during the installation: first, the axis of the eccentric shaft and the axis of the hole were difficult to coincide; Second, the outer ring of the self-aligning bearing can rotate freely in the axis plane, which is easy to enter one side and slide out the other side during installation; Third, the eccentric shaft is inclined, and the force is applied by the self weight of the shaft. The force is insufficient and uneven on the circumference of the entire bearing outer ring. Results During the installation, the outer ring of the self-aligning bearing was tilted and jammed, and the bearing could not enter the hole. Many efforts failed.

 

2 Problem solving

After analysis, it is believed that the main reason for the installation failure of the self-aligning bearing is the free rotation of the bearing outer ring and the uneven force application. Inspired by the fitter workpiece fixture, the technician made three sets of afterburner clamps. Use the three uniformly distributed gland bolt holes on the hole wall to evenly distribute the force on the oil deflector, and add a cushion block between the bearing outer ring and the oil deflector at the stressed position to transfer the force, increase the stiffness, and limit the rotation of the outer ring, as shown in Figure 3.

 

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1. Jacking screw; 2. Positioning screw; 3. Plywood; 4. Cushion block; 5. Eccentric shaft; 6. Oil deflector; 7. Cushion block; 8. Self aligning bearing Fig. 3 Eccentric shaft installation method II

 

During installation, three people shall screw the jacking screw at the same time and apply force to the outer ring of the bearing through the oil deflector. Remove the cushion block immediately after the bearing has entered the hole. When installing the bearing at the other end of the shaft, directly push the jacking screw of the afterburner onto the outer ring of the bearing to apply force. After the eccentric shaft is installed into the moving jaw hole, other parts can be assembled according to the requirements and steps.

 

3 Conclusion

During the installation of eccentric shaft, due to the use of an afterburner, the difficulty of uneven stress on the circumference of the bearing outer ring during the installation of large self-aligning roller bearings was overcome, and the installation accuracy and quality were ensured, which won time for the installation of crusher chamber equipment.

 

More about VISTA Spherical Roller Bearing:

Spherical roller bearings have good self-aligning ability and can perform during the shaft deflection under load or the shaft misalignment in mounting. This type of bearings has heavy load carrying capacity and anti-impact ability. In addition to radial loads, they can also carry axial loads in two directions. As a spherical roller bearing manufacturer, Vista mainly offers the following series for customers: 22200 series spherical roller bearing22300 series spherical roller bearing21300 series spherical roller bearing,  23000 series spherical roller bearing,  23100 series spherical roller bearing,  23200 series spherical roller bearing23900 series spherical roller bearing,  24000 series spherical roller bearing,  24100 series spherical roller bearing. The type with lubricating oil hole in the inner ring can also be supplied.

 

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2022-11-21

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