Cause and judgment of drill pipe sliding down

Fault cause:

The drill pipe is fixed on the main winch drum through the steel wire rope, and the drill pipe can be raised or lowered accordingly when the drum is wound or released with the steel wire rope. The power of the drum comes from the main winch motor that has been decelerated for many times. Its stop is realized by the brake directly installed on the reducer. During the lifting or lowering of the drill pipe, if the operating handle is returned to the middle position and the drill pipe cannot stop quickly, there may be three reasons: first, the brake lag; Second, the two hydraulic locks at the outlet of the motor end fail, and the motor cannot stop rotating immediately under the effect of the torque of the wire rope; Three reasons are easy to be ignored. All engineering drilling rigs have a drill pipe release function. The function is that the solenoid valve 3 provides release brake signal oil, and then the solenoid valve 2 connects the oil inlet and outlet of the main winch motor through two oil pipes, so as to ensure that the drill bit can always contact the working face and have a certain pressure during drilling. Under other working conditions, the solenoid valve 2 will disconnect the two oil pipes leading to the inlet and outlet of the motor. If the disconnection is not timely, the above-mentioned fault phenomenon will occur.