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Vertical mill shaft bearing installation

Date:2019-07-02 17:51     writer:cement editor     Views:

Grinding roller is one of the key components of vertical grinding. The manufacture of roller directly affects the performance and quality of mill. The roller of domestic vertical mill usually has a series of problems, such as short service life of roller bearing, easy to be stuck, high oil temperature of grinding roll and so on. The above problems are caused by improper installation of roller bearings. According to the manufacturing experience of LOESCHE vertical mill, this paper introduces a method of installation and disassembly of vertical grinding bearing, which can be used as a reference for vertical mill manufacturers and users in order to improve the quality of roller manufacturing and reduce the maintenance cost of roller.

1 bearing description

The grinding roller is equipped with a NU cylindrical roller bearing and an X-shaped double row tapered roller bearing. The inner and outer rings of both bearings can be separated freely. The inner ring of the tapered bearing can be integrated or divided into two parts.

2 installation of bearings

2.1 installation aids

(1) The crane (capable of lifting a grinding roller);

(2) the worktable used for vertically placing the grinding roller;

(3) A fuel tank for heating bearings in oil bath.

2.2 preparations

The installation process of bearings must be dustproof and moisture-proof. Therefore, the assembly workshop must be dry and dust-free, and all components to be assembled must be absolutely clean, free of iron chips, no pouring shedding, etc. For new bearings, the various parts of the bearing should be unpacked before assembly. Tapered roller bearings, including inner ring, outer ring and spacer ring, are packed separately. Cylindrical roller bearings, including inner ring and outer ring, are also packed separately. Bearings should be well preserved and generally not washed unless in some cases the bearings are dirty during assembly. At this time, you can wash with washed gasoline or light gasoline (pay attention to fire prevention). Integral One bearing should be rotated during cleaning. Immediately after the bearing is dried, apply oil or grease to prevent rust.

2.3 installation of bearings

(1) Place the roller shaft vertically, and one end of the mounting bearing is up. Take out the inner ring of the cylindrical roller bearing, and put it in the oil tank for slightly heating. The heating temperature shall not be lower than 50 ℃, and the maximum temperature shall not exceed 100 ℃ (note: The heating shall be carried out on an oil bath or a heating plate, and no open fire flare shall be used. In the case of an emergency, only a professional bearing assembly is allowed to use the micro-fire flare). Position the inner ring of the bearing with grease and install the inner ring in place until it is in contact with the shoulder.

(2) Install the inner isolation sleeve in place.

(3) the inner ring and ball cage assembly of conical ball bearing are heated to 100 ℃ by oil bath method, and the bearing components are installed on the roller shaft until the isolated shaft sleeve is contacted.

(4) The shaft end cover is fixed to the shaft end with a bolt to compress the installed parts.

(5) The hub is placed in an annealing furnace for heating (because the heating process takes several hours, it is recommended that this process be carried out at the evening before the installation so that it is heated in an annealing furnace for a whole night). The heating temperature shall be controlled at 80-100 & deg; C (if there is no annealing furnace, an oil bath method can be used).

(6) The hub is taken out from the annealing furnace, the end cover is screwed on the hub, the hub is vertically placed on the workbench, and a section of the end cover is down. The height of the working table shall be moderate, that is, when the bearing is installed in place, the roller shaft shall have a certain distance from the ground after the roller shaft is inserted, so as to ensure the free rotation of the roller shaft.

(7)Insert the outer ring and ball holder assembly of cylindrical roller bearing until the end cap is contacted.

(8) install the outer isolation sleeve until it touches the outer ring of the cylindrical roller bearing.

(9) vertically load the roller shaft and the pre-installed bearing parts into the hub from above.

(10) when inserting the inner ring of a cylindrical roller bearing into the ball cage assembly, the roller shaft should be rotated to avoid bearing scratches.

(11) once the tapered roller bearing supports the shaft, the roller shaft should be rotated again. In this way, the reasonable clearance of conical roller bearing can be obtained and the roll tilt can be avoided.

(12) Install the upper outer ring of the tapered roller bearing into the hub until it contacts the spacer ring of the bearing. And the roller shaft is rotated again.

(13)Tighten the stuffing cap on the hub while rotating the roller shaft to press the outer ring of the bearing. During the cooling of the hub, tighten the bolt several times with a torque wrench and turn the roller shaft at the same time.

(14) After the hub is cooled, tighten the bolts on the end cap again with a torque wrench.

The above-mentioned installation process shall be carried out without interruption so that both the hub and the bearing assembly are in a high temperature and an expanded state. After the correct tightening of all the screws, place the grinding roller horizontally, so that the installation of the roller bearing

And the work is completed completely, and the installation work of the subsequent sealing device can be carried out.

3. Disassembly of the bearing

3.1 Auxiliary tools for disassembly

(1) Crane.

(2)Hydraulic jack with stroke of 70~100mm and load of 100t.

(3) one manual hydraulic pump.

3.2 preparations

Remove roller hub cover, shaft end cover and hub end cover. The following disassembly must be carried out in a vertical position of the roller. The hub will be detached from the roller shaft upward.

3.3 Bearing Removal

(1) Remove the upper outer ring of the tapered roller bearing on the hub: unscrew the plug on the hub end face, and drive the high-pressure oil into the oil hole through the manual hydraulic pump, and the outer ring of the bearing will contract under the action of high-pressure oil so that the outer ring can be removed from the hub without difficulty (note: The outer ring is provided with a threaded hole for mounting the eyebolt.

(2) In addition, we can also take the method of spraying liquid nitrogen or dry ice on the outer ring, due to the sharp decrease of the temperature, the outer ring of the bearing is contracted so as to generate looseness in the hub, so that it can be removed.

(3)Remove the inner ring and ball holder assembly of the tapered roller bearing on the shaft:unscrew the plug on the shaft end face, drive the high-pressure oil into the oil hole through the manual hydraulic pump, and the inner ring of the bearing will expand under the action of high-pressure oil, so that the bearing can be removed from the shaft without difficulty.

(4) Remove the inner spacer between the tapered roller bearing and the cylindrical roller bearing: hook the step on the spacer with an iron hook and pull it out.

(5) Lift the outer ring with the lower part of the tapered roller bearing, the outer spacer sleeve and the outer ring of the cylindrical roller bearing and the hub of the ball cage from the shaft.

(6)Using the method in Step, remove the remaining outer race of the tapered bearing from the hub.

(7) remove the outer isolation sleeve and cylindrical roller bearing from the hub.

(8) the inner ring of cylindrical roller bearing can not be removed by manual pump. The inner ring can be heated by micro fire so that the inner ring of the cylindrical roller bearing can be removed from the shaft (if the inner ring of the bearing does not have to be replaced, this step can not be done).

4 concluding remarks

The installation and disassembly process of roller bearing is complex and strict. Reasonable installation and disassembly method and correct installation and disassembly sequence can improve the service life of roller bearing and thus improve the overall performance of mill.

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