Analysis of the phenomenon of rail gnawing by trolley of bridge crane
Analysis of the phenomenon of rail gnawing by trolley of bridge crane
When the bridge crane is running, the wheel rim and the track contact, resulting in extrusion friction, increasing the operating resistance of the mechanism, and causing serious wear of the wheel rim or track, which is the wheel gnawing rail. Wheel gnawing rail is difficult to avoid, slight gnawing rail does not affect the normal use of the crane, serious gnawing rail will produce large noise and vibration, wheel rim and track severe wear, so that the wheels and track scrap in a short period of time, but also increase the operating resistance, so that the crane during the operation of the swing, causing safety hazards, affecting the normal work of the crane. Crane wheel gnawing rail is the most harmful, so this paper mainly discusses the gnawing rail of the wheel of the truck.
1. Wheel gnawing phenomenon
There are various forms of wheel gnawing rail, sometimes the inside rim of one wheel gnawing rail, the outside rim of the other wheel gnawing rail, sometimes the wheel gnawing rail only when a certain section of track is running, sometimes only one wheel gnawing rail and so on. Check whether the wheel gnaws the rail, can be judged from the following signs:
(1) There is a bright trace on the side of the track, and in severe cases there are burrs or strips of iron filings peeling off;
(2) There are bright spots and burrs on the inside of the wheel rim.
(3) When the crane is starting and braking, the car body will deviate and twist.
(4) When the crane is driving, there is a significant change in the wheel rim and track clearance within a short distance.
2. Cause analysis of wheel gnawing rail
(1) The main reasons for the track
The relative elevation deviation of the two tracks exceeds the standard range, making the car body tilt to one side; The horizontal bending of the track is too large beyond the tolerance range; The overall or local gauge of the two tracks is out of whack; Rail gnawing is caused by the sinking of track foundation or the deformation of beam structure.
(2) The reason for the wheel
The diameter deviation of the two active wheels is too large, so that the running speed of the wheels on both sides is different, and the running of the car body is skewed; Horizontal and vertical deflection of the wheel over the vehicle body running skew or uneven wear of the wheel rolling surface; The wheel pitch and diagonal are not equal so that the car body loses its due channeling momentum when it runs, resulting in rail gnawing.
(3) The main reasons for the bridge
The downwarping of the main beam causes the change of wheel pitch of the cart, resulting in rail gnawing; The diagonal deviation caused by the side bending of the main beam makes the wheel pitch of the cart change, resulting in rail gnawing.
(4) The main reasons for the transmission system
In the operation mechanism of the trolley driven separately, the two motors are not synchronized, causing the wheel running speed to be different, resulting in rail gnawing; In the operation mechanism of the big car driven respectively, the clearance of the couplings and the reducer on both sides is different, the difference is too large, and the adjustment tightness of the two brakes is different, causing the wheel running speed to be different, resulting in rail gnawing.
The above analysis from four aspects of the wheel gnawing rail reasons, sometimes the wheel gnawing rail is one of the reasons, sometimes is the result of several reasons at the same time. Therefore, it is necessary to carefully analyze the actual situation of rail gnawing, take corresponding measures for specific reasons, comprehensive treatment, and reduce the phenomenon of rail gnawing.
3. Methods to reduce the phenomenon of wheel gnawing rail
(1) Adjust or replace the track
According to the detection results of the running track of the truck, the treatment is made separately. If the relative elevation deviation and spacing of the two tracks are too large, it can be treated by adjusting the track pressure plate and the backing plate; If the horizontal bend of the track is too large, it can be straightened, and it can not be replaced; Such as the track foundation sinking or the deformation of the beam steel structure caused by rail gnawing, repair is more difficult, need to consider the whole, in the premise of not endangering the safe use of the plant, can be solved by strengthening the foundation, adding the backing plate below the track, strengthening the beam steel structure. After adjusting or replacing the track, it is necessary to measure again, check the relative elevation of the two tracks, the gauge deviation and the longitudinal and horizontal levelness of the track, and ensure that the repair quality of the track meets the national standard before it can be put into use, and the measurement results are recorded in the equipment file for reference.
(2) Repair or adjust the wheel set
Under normal circumstances, the wheel gnawing is the most common cause of wheel, so the harm of gnawing can be effectively reduced by adjusting or repairing the wheel group.
When the inspection finds that the wheel tread wear is uneven and the diameter deviation of the two wheels is too large, the wheels should be removed and sent to the machine shop to repair the wheel tread. If conditions are available, the wheel tread can be welded first and then turned, and finally the wheel tread is quenched.
When the inspection finds that the wheel skew is too large or the wheel pitch and diagonal are not equal, the test results should be carefully analyzed, and sometimes just adjust a wheel group, you can solve the horizontal and vertical skew of the wheel, the wheel pitch and diagonal are not several aspects of the problem. Try to choose a wheel set to adjust, and it is best to drive the wheel set to solve the problem. Lift the car body with a jack top, make the wheel leave the track plane 6㎜ ~ 10㎜, loosen the bolt of the wheel group, calculate the amount that needs to be adjusted according to the test result, adjust the horizontal deflection, add a pad on the vertical face of the wheel group; When the vertical deviation is adjusted, the horizontal plane of the wheel group is padded; When the wheel pitch and diagonal are adjusted, the key plate of the wheel group should be cut off, and the key plate should be welded on after adjustment. The horizontal position and vertical position of the wheel after adjustment are shown in the figure, in the shape of “inner eight”, when the crane bears the load, the wheel is just perpendicular to the force.
(3) Overhaul the transmission system
Replace the motors on both sides with motors of the same model and manufacturer, overhaul the couplings and reducer on both sides, adjust the compression of the two brake springs, so that the braking torque is equal, and ensure that the running speed of the wheels on both sides is basically equal, thus reducing the phenomenon of wheel gnawing rail.
In short, we must pay enough attention to the phenomenon of wheel rail gnawing, strengthen daily inspection work, take various effective measures to avoid and reduce the phenomenon of wheel rail gnawing, extend the service life of wheels and tracks, and improve the operation rate of equipment.
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