Created on:2021-07-15 14:03

Fault diagnosis and maintenance of zy40001937 shield hydraulic support

Fault diagnosis and maintenance of zy40001937 shield hydraulic support

(1) Fault phenomenon

ZY4000 / 19 / 37 shield type hydraulic support has the advantages of simple structure, light weight, convenient transportation, assembly, disassembly, adjustment and operation. It is the main support type used in fully mechanized working face and plays an important role in production. However, a series of serious faults such as deformation and fracture occurred at the top beam ear seat connecting the balance jack, the piston rod of the balance Jack and the pin shaft connection of the cylinder block, and even led to the fracture of the piston rod, as shown in Figure K. Among the 510 supports in a company, 31 supports had obvious deformation at the pin hole of the top beam connected with the balance jack, and 13 supports had fracture at the pin hole; Seven piston rods and four cylinder blocks of balance Jack were broken; 11 connecting ears of Jack and shield beam pin are broken, and the damage rate related to balance jack is as high as 13%, which seriously affects the production.

K.jpg

(2) Analysis of deformation and fracture

① The force analysis of the support in normal working position is shown in Fig. L. under normal conditions, the top beam and shield beam of the support are subjected to five forces, i.e. P, t, W, R and fr. the top beam and shield beam are taken as the separation body, and the moment of each force on the intersection point of the extension lines of the front and rear connecting rods is 0, from ∑ M0 = 0, and the supporting force is:

R= (6-1)

Take the top beam as the separation body, from ∑ M01 = 0, the supporting force 1, the action position x is:

X = 1/R(PL1cos α+ Th) (6-2)

Where P -- total working resistance of support column;

T -- working resistance of balance jack;

W -- the force of the caving gangue acting on the shield beam;

F -- friction coefficient between top beam and top plate;

H -- arm of force of balance Jack to O1 point;

L -- horizontal distance between O1 and O;

L1 - the horizontal distance from the intersection of the extension line of the column center line and the parallel line of the top beam passing through O1 point to O1 point;

θ—— The angle between the connecting line between O1 point and o point and the parallel line of top beam passing through O1 point is "+" below the parallel line of top beam and "-" above it;

α—— The inclination angle of column is "+" for forward tilt and "-" for backward tilt;

C-arm of gangue force w to instantaneous center o.

L.jpg

Both chambers of the balance jack may carry the load. When the piston cavity is loaded, push the top beam, t is positive; When the piston rod cavity is loaded, pull the top beam, t takes negative value. Under normal conditions, the force at the hinge of balance Jack and top beam and shield beam is R1 = R2 = T. R1 and R2 are the forces at the hinge of top beam and balance jack, shield beam and balance Jack respectively.

② The stress of the balance Jack in the abnormal working position is shown in Fig. M. when the support is in the incorrect working position of "cannon shooting", the balance jack is not only subject to the working resistance t, but also due to the interference between the piston rod and the top beam of the balance jack or the cylinder block and the guard beam, assuming that the resultant force is Q, considering the general situation, The force does not necessarily pass through the center line of the balance jack, nor is it necessarily perpendicular to the balance Jack. Therefore, according to the translation principle of the force, the balance Jack will additionally receive the force QX parallel to the jack, the force QY perpendicular to the jack, the bending moment QYT and the torsional moment qxt. T is the distance from the center axis of the force Q.

The additional force QX parallel to the jack increases the working resistance of the jack. At this time, R1 = R2 = t + QX increases the force at the pin shaft connection; The additional force QY and bending moment QYT perpendicular to the jack make the balance Jack produce bending stress, and make the piston rod or cylinder body subject to bending moment, resulting in fracture. At the same time, the force also increases the force at the pin shaft joint, which, together with T and QX, deteriorates the stress at the pin shaft, and makes the lug more vulnerable to wear, deformation and even fracture; The torsion moment qxt causes the balance Jack to twist around the axis direction and the piston rod to break, resulting in a series of faults as shown in Figure K.

(3) Summary

The incorrect working position is very unfavorable to the force of the support, which not only increases the working resistance of the balance jack, but also makes the part connected with the balance Jack subject to additional load, resulting in bending and torsion deformation, which is unfavorable to the working condition of the hydraulic support and shortens the service life of the hydraulic support. Therefore, it is necessary to operate in strict accordance with the operation rules of the support to keep the top beam of the support level. It is strictly forbidden to "shoot big guns" under the bad working conditions of uneven roof; The deformed lug seat should be repaired in time to avoid final fracture, permanent damage, impact on production and economic loss to the enterprise.

The support designer must recheck the strength of the balance jack, each connecting support and each connecting pin from the damage of the support on site, and adhere to the principle of the maximum strength of the support, the second strength of the balance jack, and the weakest strength of the connecting pin, so as to ensure that the pin will be damaged first when the equipment fails to use according to the operating procedures. This can protect the balance Jack and support support, avoid the balance Jack damage first, and even the serious failure of support fracture that cannot be solved in the production site, so as to ensure the normal use of the support and extend the service life of the support to the maximum extent.

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