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How to Keep Good Storage for the DTH Drilling Tools?
Aug 17, 2018

How to Keep Good Storage for the DTH Drilling Tools?


DTH hammer & bit 0.jpg


I. Overview 


The high-pressure DTH Hammer is an impact rock drilling tool, but unlike other rock drilling tools, the rock is always left at the bottom of the hole, and the piston directly impacts the drill bit. The compressed gas enters the impactor through the drill pipe and is then discharged from the drill bit, and the exhaust gas is used to discharge the slag. The slewing motion of the impactor is provided by the rig's turret, which is provided by the rig's propulsion mechanism and transmitted through the drill pipe to the impactor.


 Second, the structure principle



The DTH Hammer is composed of a piston, an inner cylinder, a gas distribution seat, a check valve, and a drill attachment mounted in an elongated outer cylinder, and the upper end of the outer cylinder is provided with an upper joint with a plate hand and a coupling thread. The lower end is provided with a card sleeve for connecting threads. The card bushing is mainly used to transmit propulsive force and swivel motion to the drill bit. The snap ring controls the axial movement of the drill bit, and the check valve is used to prevent debris such as lump from entering the impactor when the supply of the compressed air is stopped. During the drilling process, the drill bit is pushed into the impactor and pressed against the card holder, at which point the piston directly impacts the drill bit for rock drilling. When the drill bit is lifted off the bottom of the hole, the strong slagging is started.




 Third, the use of operating precautions


1. Reliable Lubrication


Lubrication of the DTH Hammer is achieved by the oiler on the rig, so it must be ensured that the oiler is filled with lubricant before the start of work, and remains until the next shift begins. (Summer note No. 20 mechanical oil, winter note No. 5-10 mechanical oil)


2. Before the DTH Hammer is installed in the drill pipe, operate the impact damper exhaust to remove the debris in the drill pipe, and check whether the drill pipe has lubricating oil. After connecting the impactor, check whether there is oil film on the drill spline, if it is obviously oil-free or If the amount of oil is too large, the oiler system should be adjusted.


3. When the impactor begins to drill, the propulsion damper should be operated to advance the impactor to the ground, and the impact damper is opened at the same time to make the impactor impact. At this time, care should be taken not to make the impactor rotate, otherwise it is impossible. Stabilize the drill, when the impact of a small pit to stabilize the drill, then open the rotary damper to make the impactor into normal operation.


4. During the working process, periodically check the air compressor tachometer and pressure gauge. If the rig speed drops rapidly, the drilling machine will have a fault in the drilling. If the hole wall collapses or the mud hoop is generated in the hole, it should be taken in time. Measures are excluded.


5. During the drilling process, the slag is kept in the hole at all times. If necessary, the hole is blown cleanly, that is, the impactor is lifted 150mm away from the bottom of the hole. At this time, the impactor stops the impact, and all the pressure is discharged through the center hole of the impactor. Slag.


6. If it is found that the drill bit falls off the column or the debris falls into the hole, it should be sucked out with a magnet in time.


7. Grind the drill bit teeth regularly, and the height of the cylindrical teeth after grinding is 9-9.6mm. (Our company can provide you with professional grinding tools)


8. When changing the drill bit, pay attention to the diameter change. The drill bit wear hole is not drilled. It is not possible to replace the old drill bit with a new drill bit to avoid “click drilling”.


9. High efficiency drilling and improved bit life depend on the proper fit of shaft pressure and speed. Various rock formations will affect the ratio of speed to shaft pressure. The minimum axial pressure applied to the impactor is preferably such that the impactor does not produce a rebound. The speed can be adjusted according to the particle size of the rock.


10. The impactor and the drill pipe are strictly prohibited from reversing in the hole to prevent the impactor from falling.


11. In the drilling of the lower hole, when stopping drilling, the gas supply to the impactor should not be stopped immediately, and the drilling should be carried out for strong blowing. After the slag and the rock powder are no longer discharged in the hole, the wind is stopped. Lower the drill and stop turning.




 Fourth, repair and maintenance


Under normal rock drilling conditions, the impactor is cleaned and reassembled, once every 200 hours of operation, every 100 hours when drilling water holes or slag discharge with mud. This work is carried out by a special person in the repair shop.


 Fifth. Cleaning inspection and repair


1. Thoroughly clean all the removed parts with a cleaning agent and blow dry with compressed air.


2. Repair all parts of each part, if there is bumping and scratching, use a trowel, scraper, fine stone and other grinding and repairing complete (piston parts can be stuck on the lathe). If there is hot crack and damage, replace it. .


3. Use a micrometer and inner diameter gauge to measure the large outer circumference of the piston and the inner diameter of the cylinder. If the clearance is too large, replace a new piston or cylinder.

4. Check the wear condition of the card bit sleeve, and replace it with a new one when the outer circle wears less than the outer diameter of the outer tube.


5. Check the spline wear condition of the card sleeve, and twist it with the new drill bit inserted into the card sleeve spline. If the rotation range exceeds 5mm, replace the card sleeve.


6. Lubricate the repaired parts and all parts of the parts to be assembled.



 Sixth, the assembly of the impactor



  1. Stand the lower end of the outer tube up on the ground, place the small end of the bushing down into the outer tube, and tap it into place with a copper rod.


2. Lay the big head down on the ground, apply a layer of butter to the inner thread of the outer tube, put the outer circumference of the card sleeve into the drill bit, and put the "O" ring on the snap ring to clamp the snap ring on the drill bit. At the outer circle, even the drill bit, the card bit sleeve and the snap ring are screwed into the outer tube.


3. Place the outer tube with the drill bit on the workbench, and insert the gas distribution seat into the inner cylinder with the copper rod. The piston is placed in the cylinder and one piece is pushed into the outer tube from the upper end of the outer tube. And hit it with a copper rod.


4. Insert the spring and check the valve to see if the check valve is free.


5. Apply a layer of butter to the inner thread of the upper end of the outer tube and screw the rear joint into the outer tube.


6. Use a long stick to rub the piston to see if it is free.



 Seven, Common Troubleshooting Methods


Failure 1. The lubricant is not enough or does not cause premature wear or damage.


Cause: The lubricating oil does not reach the impact structure of the impactor.


Remedy: Check the lubrication device, adjust the oiler, and increase the oil filling.


Fault 2. The impactor does not work or does not work properly.


Reason: 

1. The gas path is blocked.

2. The gap between the piston and the inner and outer cylinders is too large for the piston and the air distribution seat.

3. The impactor is blocked by dirt.

4. The piston or the tail of the drill bit is broken.


Method of exclusion:


1. Check the air pressure and check if the air circuit is clear. Check if the check valve is stuck.

2. Disassemble the impactor, check for wear and replace worn parts.

3. Disassemble the impactor and clean all internal parts inside the impactor.

4. Disassemble the impactor and replace the piston or drill.



Fault 3. The drill bit and the card sleeve are peeled off.

Cause: The impactor was not working right-handed.


Remedy: Hook off the part, ensure right turn when drilling or lifting

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