Shenyang ABT Drilling Equipment Co., Ltd.

Causes and Judgments of the Drill Pipe Slipping during the Use of Large Drilling Rigs

1. Cause of failure

The jumbo drill rig pipe is fixed to the main hoisting reel by a wire rope. The drill pipe can be raised or lowered as the roll is rolled or the wire rope is placed. The power of the reel comes from the main hoisting motor that has been decelerated several times. Its stopping is achieved by means of a brake mounted directly on the gear unit. During the lifting or lowering of the drill pipe, if the operating handle is returned to the neutral position and the drill pipe cannot be stopped quickly, there may be three reasons. One is the brake lag. Second, the two hydraulic locks at the end of the motor are out of order, and the motor cannot stop rotating immediately under the action of the wire rope torque; the third reason is easily overlooked. All jumbo drill rigs have a drill stem release function. The function is to provide the brake signal oil by the solenoid valve 3, and then the solenoid valve 2 connects the inlet and outlet ports of the main hoisting motor through the two oil pipes, thereby ensuring that the drill bit can always contact the working surface during the drilling process. There is a certain amount of pressure. In other working conditions, the solenoid valve 2 disconnects the two oil pipes leading to the motor inlet and outlet ports. If the disconnection is not timely, the above symptoms will occur.

(1) Judging the solenoid valve 2

It is judged whether the solenoid valve 2 is closed tightly: the two oil pipes leading to the solenoid valve 2 at the motor are removed, and the two oil ports of the motor end are respectively blocked by the two plugs, and then the main hoisting mechanism is operated. If it is working properly, the fault is caused by the solenoid valve 2 being closed; if it is still abnormal, it is necessary to check its components.

(2) Judging the hydraulic lock

Judging whether there is a problem with the hydraulic lock of the jumbo drill rig: Firstly, adjust the two lock cylinders. If it does not work, remove the lock and check it carefully. If the reason is not found, the ready-made lock can be used to test the installation to find the reason of fault. Because the sub-hoisted hydraulic lock is the same as the main winch, it is also possible to borrow the sub-hoisted lock. Use the replacement method to identify the quality of the main winch lock. If there are no problems with both locks, check the next step.

(3) Judging the brake signal oil

Check the speed of the brake signal oil supply and disconnection: the flow rate of the signal oil of the current engineering rig can be adjusted, that is, the time for the main hoist to release the brake can be adjusted. Therefore, for both types of rigs, the flow of the signal oil can be adjusted by its regulating valve. If the machine is still not working properly, check the tubing of the brake signal oil for blockage. If these inspection sites are normal, you can only continue to check.

(4) Judging the brake

Dismantle the brakes of jumbo drill rigs: See if the brake pistons move smoothly in the work line and repair or replace them for the cause of the malfunction.

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