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Do you know the cause of broken shaft of rotary kiln roller and how to prevent it?

Date:2019-10-28 13:23     writer:cement editor     Views:

The supporting wheel and the supporting wheel shaft are the key parts of the rotary kiln. They support all the weight of the rotary kiln together with other supporting wheels, which are not only of high value but also difficult to replace.Once the supporting wheel shaft fracture occurs, it will bring great loss to the production of enterprises. Do you know the cause of the broken shaft of rotary kiln supporting wheel and how to prevent it?

 

1. The reason for the broken shaft of rotary kiln supporting wheel


Supporting wheel and shaft generally use hot or cold installation method, the shaft and supporting wheel are closely assembled together, as the contained part of the supporting wheel shaft will receive a lot of pressure, make it produce great friction, otherwise it will be as the supporting wheel rolling elongation, and the shaft loose.Because the supporting wheel supports all the weight of rotary kiln through the shaft, the bearing is subjected to great shear stress, and because the supporting wheel is a rotating part, it is also subject to alternating stress.Not only so still have the interference of temperature stress, frictional force, force is more complex.The following from the point of view of stress other aspects of the impact, explain the reason of supporting wheel shaft fracture.


rotary kiln
 

1.1 unreasonable fit between supporting wheel and shaft


The fit interference of the supporting wheel and the shaft is usually 0.6 to 1/1000 of the shaft diameter, so as to ensure that the supporting wheel and the shaft will not become loose. However, this interference will cause the shaft to shrink neck at the end of the supporting wheel hole, resulting in stress concentration. Therefore, it is not difficult to imagine that the shaft will break here.
 

1.2 fatigue fracture


Due to the complex stress of the supporting wheel, if the supporting wheel and the shaft are considered as a whole, the maximum bending stress and shear stress of the shaft are at the corresponding place of the hole end of the supporting wheel, which is prone to fatigue under the action of alternating load, so the fracture should also occur at the end of the joint part of the supporting wheel and the shaft.
 

1.3 manufacturing defects


Axles generally need by ingot or round steel forging, machining, heat treatment process is complete, such as middle and failed to check out, once appear, defects such as ingot the impurity, forging, heat treatment, such as insect skin appear in the micro cracks, these defects not only make the bearing load capacity is limited, also produce stress concentration, so as the source, once the rotary kiln axial crack expansion, the fracture is inevitable.


Rotary kiln roller
 

1.4 improper temperature stress or stress


Heating of large tile of rotary kiln is a common fault. If the operation and maintenance is not proper, it is easy to cause surface crack of supporting wheel shaft.When big tile heating, the temperature of the shaft must be very high, then if the shaft rapid cooling, due to the shaft of the internal cooling slowly, only through a sharp contraction in the shaft surface crack to release huge contraction stress, surface crack produces stress concentration at this moment, in under the action of alternating stress, crack once appear, ring to expand, and reached a certain degree of fracture occurs.The same is true for the supporting wheel with too much stress. For example, improper adjustment will make the shaft or a section of the shaft bear too much stress, which is easy to cause the fracture of the supporting wheel shaft.
 

2. Prevention of fracture of rotary kiln supporting wheel shaft

 

2.1 supporting wheel and axial inclusion region adopt different interference


For roller and the shaft interference quantity is very big, so roller inside Kong Duan hot charging cooling after tightening, caused the shaft at the neck, the stress concentration is too large, so in the process of design, manufacture, installation, to the ends of the wheel inner hole (range of about 100 mm), reduced gradually from inside to outside interference, to alleviate neck, the phenomena of narrow amount can be gradually reduced to a third to half of the over surplus quantity of the middle, so as to avoid or reduce the necking phenomenon.
 

2.2 comprehensive flaw detection to eliminate defects


Defects will reduce the bearing capacity of rotary kiln shaft, but also cause stress concentration, often leading to fracture accidents, great harm, must be paid attention to, for the roller shaft, must be detected in advance, such as the selection of materials before processing, select no problem materials;It is also necessary to detect defects, eliminate defects, ensure the inherent quality of the shaft, ensure the machining accuracy of the shaft, and eliminate the crack source and stress concentration source.


Rotary kiln roller
 

2.3 reasonably adjust the large rotary kiln to reduce the additional load


The multi-root supporting wheel shaft supports all the weight of the rotary kiln through the supporting wheel. The load is very large. If the installation or maintenance is not adjusted properly, the partial load will be generated.When the center line of rotary kiln is not consistent, it will cause one supporting wheel to be stressed too much.When the axis of the supporting wheel and the Central Line of the rotary kiln are not parallel, the stress on one side of the shaft will be increased.If the stress is too large and improper, it will lead to the heat of large tile, which will also cause damage to the shaft due to the large stress somewhere in the shaft. Therefore, the maintenance and adjustment of the kiln must be paid attention to, to avoid or reduce the additional load, so that the kiln can run lightly.In the process of maintenance, avoid fire and welding on the shaft, avoid grinding the grinding wheel on the shaft, so as to reduce the damage to the shaft.
 

2.4 do not quench the hot shaft during operation


In the operation of rotary kiln, large tile will cause heat for some reasons, in order to reduce the production loss, some units often take rapid cooling, which is easy to cause the shaft surface micro-cracks, so to take slow cooling but method, to avoid rapid cooling.

The fracture of support wheel shaft is the result that comprehensive reason causes more, want to be analysed according to actual production environment specific, how do you still have what doubt to be able to leave a message with us.

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