The method for judging the fault of the drill pipe sliding down in hydraulic drilling RIGS

Key words:

After a certain company's hydraulic rotary drilling rig has been in use for some time, when the operation handle is returned to the middle position during the lifting or lowering of the drill pipe, the drill pipe does not stop immediately. It always slides down several tens of centimeters before it can stop moving.

The drill pipe is fixed to the main hoist drum by steel wire rope. Only when the drum is wound or released by the steel wire rope can the drill pipe be raised or lowered accordingly. The power of the drum comes from the main hoist motor that has been decelerated many times, and its stop is achieved by the brake directly installed on the reducer.

1. Cause of the malfunction

During the process of lifting or lowering the drill pipe, if the operation handle is returned to the center position but the drill pipe cannot stop quickly, there may be three reasons: the first is braking lag; The second issue is that the two hydraulic locks at the motor's end outlet are malfunctioning, and the motor cannot stop rotating immediately under the torque of the steel wire rope. The third reason is often overlooked, that is, all the drilling RIGS of the Italian Tuli Company have a drill pipe release function. This function is provided by the solenoid valve Y3 to release the brake signal oil, and then the solenoid valve Y2 connects the oil inlet and outlet of the main hoist motor through two oil pipes, thus ensuring that the drill bit can always be in contact with the working surface and have a certain pressure during the drilling process. Under other working conditions, the solenoid valve Y2 will disconnect the two oil pipes leading to the oil inlet and outlet of the motor. If the disconnection is not timely, the above-mentioned fault phenomenon will occur.

2. Diagnostic methods

(1) Determine whether the solenoid valve Y2 is tightly closed

Remove the two oil pipes leading from the motor to the solenoid valve Y2, and use two plugs to block the two oil ports at the motor end respectively. Then operate the main winch mechanism. If it works normally, it indicates that the fault is caused by the solenoid valve Y2 not closing tightly. If it is still abnormal, its components need to be inspected.

(2) Determine whether there is a problem with the hydraulic lock

First, adjust the two lock cores. If they don't work, then remove the lock for a thorough inspection. If the cause cannot be found, you can use an existing lock for an installation test to identify the cause of the fault. Since the hydraulic lock of the secondary hoist is the same as that of the main hoist, the lock of the secondary hoist can also be borrowed and replaced one by one to identify the quality of the main hoist lock. If both locks are fine, proceed to the next step of inspection.

(3) Check the speed at which the brake signal is supplied and disconnected

The flow rate of the signal oil of the R-622 and R-825 drilling RIGS produced by Tuli Company can be adjusted, that is, the time when the main hoist releases the brake can be adjusted. Therefore, for both types of drilling RIGS, the flow rate of the signal oil can be adjusted through their regulating valves. If the machine's working condition remains abnormal, it is necessary to check whether the oil pipe of the brake signal oil is blocked. If all these examination areas are normal, we can only continue the examination

(4) Disassemble and inspect the brake

Check whether the brake piston moves smoothly during the working stroke and repair or replace it based on the cause of the fault.