The rotary drilling rig has two winches, a main winch and an auxiliary winch. The auxiliary winch plays some auxiliary roles, such as hanging a casing, and the main winch is used to hang the drill rod. Under normal circumstances, the main winch is responsible for the weight of the drill rod and the drill bit. However, when the drill bit is in the air, it will be affected by the suction of mud and the friction of the hole wall. Therefore, the lifting force of the main winch is generally greater than the gravity of the drill rod plus the drill bit. Sometimes, if there are some collapsed objects in the air pressing on the drill rod, the characteristics of the main winch lifting force can be better reflected.
The main winch of the rotary drilling rig is the main equipment for lifting the drill rod of the rotary drilling rig. It is a component that is used frequently and prone to failure during the piling process of the rotary drilling rig. Common faults of the main winch include no action of the main winch, no floating of the main winch, sudden drop of the drill rod during the lowering of the drill rod, the main winch can only be lowered, and the drill rod falls slowly. The troubleshooting methods are as follows.
1. The main winch does not move
This fault is manifested as the main winch does not move when the main winch control handle is pulled. The reasons are as follows: first, the main oil circuit and pilot oil circuit are faulty; second, the brake release opening pressure is insufficient; third, the motor, BVD balance valve, brake, reducer, etc. are faulty.
(1) Check the main oil circuit and pilot oil circuit
Pull the travel or rotation control handle and observe the pressure value displayed on the main controller. If there is no pressure in the main oil circuit, check the main pump and main overflow valve for faults; if there is no pressure in the pilot oil circuit, check the pilot pump and pilot overflow valve for faults.
If the pressure in the main oil circuit or pilot oil circuit is normal, check whether the main winch pilot valve can be opened. If the pilot valve does not open, check whether the pilot valve solenoid is energized. If it is not energized, check the circuit fault; if it is energized, install the valve on the auxiliary winch and observe whether the auxiliary winch moves.
If the auxiliary winch does not move, it means that the pilot solenoid valve core is stuck and should be disassembled for cleaning or replacement; if the auxiliary winch moves normally, check the brake opening pressure.
(2) Check the brake opening pressure
Lift the drill pipe off the ground by manipulating the boom so that the main winch can bear the weight of the drill pipe. Press the floating button. If the main winch can rotate, it may be caused by insufficient brake release pressure. At this time, use a pressure gauge to detect the brake release oil circuit pressure. If the pressure is insufficient, the pressure of the pressure reducing valve can be increased so that the pressure can release the brake. If the brake release pressure reaches the standard, press the floating button again and the main winch still does not move, then check whether the main winch motor and BVD balance valve are faulty.
(3) Check the main winch motor and BVD balance valve
Remove the main winch motor fixing bolts, pull out the main winch motor output shaft from the transmission (the main winch motor oil pipe is not removed), operate the main winch handle, and observe whether the main winch motor can rotate. If the main winch motor cannot rotate, it means that the main winch motor and BVD balance valve are faulty, and the main winch motor assembly should be replaced (the main winch motor and BVD balance valve are integrated structures); if the main winch motor can rotate after being pulled out, the brake should be checked.
(4) Check the brake
Disassemble the brake assembly (lower the drill mast before disassembling and let the drill rod touch the ground so that the main winch is not under stress), check whether the brake pad is sintered and whether the brake cylinder seal is leaking. If the brake pad is sintered and the seal is leaking, it should be replaced. If the brake is not faulty, check the reducer.
(5) Check the reducer
After excluding the possibility of hydraulic system and brake system failure, if the main winch still cannot move, it can only be that the gear or bearing in the reducer is damaged. If this part is damaged, it cannot be repaired on site. It is recommended to replace the assembly first, and then return the replaced reducer to the factory for repair.
2. The main winch does not float
This fault is manifested as the drill rod cannot drill down by its own weight when the floating button is pressed during the drilling operation of the rotary drilling rig. The reason is usually that the floating solenoid valve is not opened or the brake is not released.
(1) Check whether the floating solenoid valve is energized
The floating solenoid valve of the new rotary drilling rig has an indicator light to show its on and off status. During the inspection, observe whether the indicator light is on to determine whether the floating solenoid valve is energized. If the indicator light of the floating solenoid valve is not on, you can use a multimeter to check whether the floating solenoid valve is energized.
If the floating solenoid valve is not energized, you should find the circuit fault; if the floating solenoid valve is energized, you should disassemble and clean the floating solenoid valve core, or replace it with a new floating solenoid valve.
(2) Check whether the brake is released
At this time, you should first check whether the brake release pressure is too low. If the pressure is too low, adjust the pressure of the pressure reducing valve to increase the pressure until it can fully open the brake. If the brake is still not released after the brake release pressure reaches the standard, it may be that the brake pad is sintered. The brake can be removed for inspection.
3. Drill drop
This fault is manifested as a sudden and rapid drop during the lowering of the drill rod. The reason is low main winch pressure or stuck floating solenoid valve.
(1) Check the main winch pressure
During the drill lifting operation, observe the display of the main controller pressure gauge. If the main winch pressure value is too low, adjust the overflow valve pressure until it meets the specified value.
(2) Check whether the floating solenoid valve is stuck
There are two reasons for the floating solenoid valve to get stuck: one is that the outside temperature is too low, and the other is that the hydraulic oil is contaminated. If the outside temperature is too low, causing the hydraulic oil to become viscous, the operation should be carried out after the drilling rig is preheated. At this time, the thermostat of the hydraulic oil cooling fan should also be checked. If the set temperature is too low, the thermostat should be adjusted or replaced. If the floating solenoid valve is stuck due to hydraulic oil contamination, the floating solenoid valve should be cleaned or replaced. If necessary, the hydraulic oil and oil filter should be completely replaced.
4. The main winch can only be lowered
This fault manifests itself as the drill rod can only be lowered but not lifted when operating the drill. The reasons may be that the main and auxiliary winch switching solenoid valves do not work, the overflow valve is stuck, or the set pressure is too low.
First, check whether the main and auxiliary winch switching pilot solenoid valves are stuck. If they are stuck, the solenoid valve core can be disassembled for cleaning or replacement.
Second, check whether the overflow valve is stuck. If it is stuck, the overflow valve can be disassembled for inspection, and then reassembled after cleaning.
Finally, check the overflow pressure of the overflow valve when the main winch is lifted. If the pressure is too low, it should be adjusted to the specified value.
5. The drill rod falls slowly
This fault is manifested as the drill rod slowly falling after the machine is stopped. The reasons may be the floating solenoid valve stuck or the brake slipping.
If the floating solenoid valve is stuck, the drill rod may fall slowly even if the machine is not stopped. At this time, the floating solenoid valve can be disassembled, the valve core can be disassembled and cleaned, or the valve can be replaced.
After the brake pads are worn for a long time, they will not be able to provide sufficient braking force, which will cause brake failure and slow fall of the drill rod. At this time, replace the brake pads.
The maintenance and care of the drilling rig should be done well to ensure the cleanliness of the hydraulic oil, prevent contaminants from entering the hydraulic system, damage the hydraulic components and cause failures. Regularly check the brake pressure of the winch to ensure that the brake friction pads are opened normally.
