Use and maintenance of impactor

summary

High wind pressure impactor is a kind of percussive rock drilling tool, but different from other rock drilling tools, it always stays at the bottom of the hole during rock drilling, and the piston directly impacts the drill bit. The compressed gas enters the impactor through the drill pipe, and then is discharged from the drill bit. The discharged waste gas is used for slag removal. The rotary motion of the impactor is provided by the rotary head of the drilling rig, and the shaft thrust is provided by the propulsion mechanism of the drilling rig and transmitted to the impactor through the drill pipe.


II. Structure principle


The DTH impactor is composed of a piston, an inner cylinder, a valve seat, a check valve, a drill bit accessory, etc. installed in a slender outer cylinder. The upper end of the outer cylinder is equipped with an upper joint with a wrench port and a connecting thread, and the lower end is equipped with a clamping sleeve with a connecting thread. The clamping sleeve is mainly used to transmit the propulsive force and rotary 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 rock slag from entering the impactor when the supply of air is stopped. During drilling, the drill bit is pushed into the impactor and pressed on the drill sleeve. At this time, the piston directly impacts the drill bit for rock drilling. When the drill bit is lifted away from the bottom of the hole, start forced blowing and slag removal.


III. precautions for use and operation


1. ensure reliable lubrication

The lubrication of the impactor is realized through the oiler on the drilling rig. Therefore, it must be ensured that the oiler is filled with lubricating oil before the start of each shift, and there is still residual oil before the start of the next shift. (note No. 20 machine oil in summer and No. 5-10 machine oil in winter)

2. before installing the impactor on the drill pipe, operate the impact air valve to exhaust and remove the sundries 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 spline of the drill bit. If there is obviously no oil or the oil quantity is too large, adjust the oiler system.

3. when the impactor starts drilling, the propelling air valve shall be operated to make the impactor feed forward and hold the ground. At the same time, the impact air valve shall be opened to make the impactor impact. At this time, attention shall be paid not to make the impactor rotate, otherwise it is impossible to stabilize the drill. When a small pit is impacted to stabilize the drill, the rotary air valve shall be opened to make the impactor work normally.

4. check the air compressor tachometer and pressure gauge regularly during the working process. If the speed of the drilling rig drops rapidly and the pressure increases, it indicates that the drilling rig is faulty. For example, the hole wall collapses or mud hoops are generated in the hole, and measures should be taken to eliminate them in time.

5. during the drilling process, there shall always be no rock slag in the hole. If necessary, the hole shall be forcibly purged, that is, the impactor shall be lifted 150mm away from the hole bottom. At this time, the impactor stops impacting, and all air pressure shall be discharged through the central hole of the impactor.

6. if the drill bit falls off the column or debris falls into the hole, it shall be sucked out with a magnet in time.

7. regularly grind the drill bit column teeth. The height of the column teeth after grinding is 9-9.6mm.

8. when replacing the drill bit, pay attention to the diameter change. The drill bit wear hole is not drilled. Do not replace the old drill bit with a new drill bit to avoid "sticking".

9. high efficiency drilling and improving the service life of drill bit depend on the proper coordination of axial pressure and rotating speed. Various rock formations will affect the ratio of rotating speed and axial pressure. The lowest axial pressure applied to the impactor is that the impactor does not rebound when it is working. The rotating speed can be adjusted according to the particle size of rock slag.

10. the impactor and drill pipe shall not be reversed in the hole to prevent the impactor from falling into the hole.

11. in the process of drilling the downward hole, when the drilling is stopped, the air supply to the impactor cannot be stopped immediately. Instead, the drill should be lifted for forced blowing. After no rock slag and rock powder are discharged from the hole, the air shall be stopped, and then the drilling tool shall be put down to stop the rotation.


IV. repair and maintenance

Under normal rock drilling conditions, the impactor shall be overhauled, cleaned and reassembled once every 200 hours, and once every 100 hours when drilling a water hole or discharging slag with mud. This work shall be carried out by a specially assigned person in the repair workshop.


V. cleaning, inspection and repair


1. thoroughly clean all removed parts with cleaning agent and dry them with compressed air.

2. check and repair all parts of all parts. If there are bumps and scratches, polish and repair them completely with files, scrapers, fine oilstones, etc. (piston parts can be stuck on the lathe for grinding). If there are thermal cracks and damages, replace them.

3. measure the large outer circle of piston and the inner diameter of cylinder with micrometer and inner diameter gauge. If the fit clearance is too large, replace it with a new piston or cylinder.

4. check the wear of the clamping sleeve. When its outer circle is worn to less than the outer diameter of the outer tube, replace it with a new one.

5. check the wear of the clamping sleeve spline, insert a new drill bit into the clamping sleeve spline and twist it. If the rotation range exceeds 5mm, replace the clamping sleeve.

6. apply lubricating oil to all parts of repaired parts and all parts to be assembled.


Vi. assembly of impactor


1. put the lower end of the outer pipe up on the ground, put the small end of the bushing down into the outer pipe, and knock it in place with a copper rod.

2. stand the big end of the drill bit down on the ground, apply a layer of grease to the internal thread of the outer tube, put the big outer circle of the drill bit sleeve down, put the "O" ring on the snap ring, and clamp the snap ring on the small outer circle of the drill bit, and screw the drill bit, the drill sleeve and the snap ring into the outer tube.

3. put the outer tube with drill bit on the workbench, drive the valve seat into the inner cylinder with copper rod, put the piston into the cylinder, and push one piece into the outer tube from the upper end of the outer tube. And knock it in place with a copper rod.

4. put in the spring and check valve to see if the check valve moves freely.

5. apply a layer of grease to the internal thread at the upper end of the outer tube, and screw the rear joint into the outer tube.

6. poke the piston with a long rod to see if it can move freely.


VII. Common troubleshooting


Fault 1 Insufficient lubricating oil or premature wear or damage.

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

Troubleshooting: check the lubricating device, adjust the oiler, and increase the oil injection amount.


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

reason:


1. the air circuit is blocked.


2. the clearance between piston and inner and outer cylinders, piston and valve seat is too large.


3. the impactor is blocked by dirt.


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


Exclusion method:


1. check the air pressure and whether the air circuit is unblocked. Check valve is stuck.


2. disassemble the impactor, check the wear and replace the worn parts.


3. disassemble the impactor and clean all internal parts in the impactor.


4. disassemble the impactor and replace the piston or drill bit.




Fault 3 The drill bit and the clamping sleeve fall off.


Cause: the impactor did not rotate right when it was working.


Troubleshooting: hook up the fallen parts, and ensure right turning when drilling or lifting.


summary


High wind pressure impactor is a kind of percussive rock drilling tool, but different from other rock drilling tools, it always stays at the bottom of the hole during rock drilling, and the piston directly impacts the drill bit. The compressed gas enters the impactor through the drill pipe, and then is discharged from the drill bit. The discharged waste gas is used for slag removal. The rotary motion of the impactor is provided by the rotary head of the drilling rig, and the shaft thrust is provided by the propulsion mechanism of the drilling rig and transmitted to the impactor through the drill pipe.




II. Structure principle


The DTH impactor is composed of a piston, an inner cylinder, a valve seat, a check valve, a drill bit accessory, etc. installed in a slender outer cylinder. The upper end of the outer cylinder is equipped with an upper joint with a wrench port and a connecting thread, and the lower end is equipped with a clamping sleeve with a connecting thread. The clamping sleeve is mainly used to transmit the propulsive force and rotary 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 rock slag from entering the impactor when the supply of air is stopped. During drilling, the drill bit is pushed into the impactor and pressed on the drill sleeve. At this time, the piston directly impacts the drill bit for rock drilling. When the drill bit is lifted away from the bottom of the hole, start forced blowing and slag removal.




III. precautions for use and operation


1. ensure reliable lubrication


The lubrication of the impactor is realized through the oiler on the drilling rig. Therefore, it must be ensured that the oiler is filled with lubricating oil before the start of each shift, and there is still residual oil before the start of the next shift. (note No. 20 machine oil in summer and No. 5-10 machine oil in winter)


2. before installing the impactor on the drill pipe, operate the impact air valve to exhaust and remove the sundries 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 spline of the drill bit. If there is obviously no oil or the oil quantity is too large, adjust the oiler system.


3. when the impactor starts drilling, the propelling air valve shall be operated to make the impactor feed forward and hold the ground. At the same time, the impact air valve shall be opened to make the impactor impact. At this time, attention shall be paid not to make the impactor rotate, otherwise it is impossible to stabilize the drill. When a small pit is impacted to stabilize the drill, the rotary air valve shall be opened to make the impactor work normally.


4. check the air compressor tachometer and pressure gauge regularly during the working process. If the speed of the drilling rig drops rapidly and the pressure increases, it indicates that the drilling rig is faulty. For example, the hole wall collapses or mud hoops are generated in the hole, and measures should be taken to eliminate them in time.


5. during the drilling process, there shall always be no rock slag in the hole. If necessary, the hole shall be forcibly purged, that is, the impactor shall be lifted 150mm away from the hole bottom. At this time, the impactor stops impacting, and all air pressure shall be discharged through the central hole of the impactor.


6. if the drill bit falls off the column or debris falls into the hole, it shall be sucked out with a magnet in time.


7. regularly grind the drill bit column teeth. The height of the column teeth after grinding is 9-9.6mm.


8. when replacing the drill bit, pay attention to the diameter change. The drill bit wear hole is not drilled. Do not replace the old drill bit with a new drill bit to avoid "sticking".


9. high efficiency drilling and improving the service life of drill bit depend on the proper coordination of axial pressure and rotating speed. Various rock formations will affect the ratio of rotating speed and axial pressure. The lowest axial pressure applied to the impactor is that the impactor does not rebound when it is working. The rotating speed can be adjusted according to the particle size of rock slag.


10. the impactor and drill pipe shall not be reversed in the hole to prevent the impactor from falling into the hole.


11. in the process of drilling the downward hole, when the drilling is stopped, the air supply to the impactor cannot be stopped immediately. Instead, the drill should be lifted for forced blowing. After no rock slag and rock powder are discharged from the hole, the air shall be stopped, and then the drilling tool shall be put down to stop the rotation.




IV. repair and maintenance


Under normal rock drilling conditions, the impactor shall be overhauled, cleaned and reassembled once every 200 hours, and once every 100 hours when drilling a water hole or discharging slag with mud. This work shall be carried out by a specially assigned person in the repair workshop.




V. cleaning, inspection and repair


1. thoroughly clean all removed parts with cleaning agent and dry them with compressed air.


2. check and repair all parts of all parts. If there are bumps and scratches, polish and repair them completely with files, scrapers, fine oilstones, etc. (piston parts can be stuck on the lathe for grinding). If there are thermal cracks and damages, replace them.


3. measure the large outer circle of piston and the inner diameter of cylinder with micrometer and inner diameter gauge. If the fit clearance is too large, replace it with a new piston or cylinder.


4. check the wear of the clamping sleeve. When its outer circle is worn to less than the outer diameter of the outer tube, replace it with a new one.


5. check the wear of the clamping sleeve spline, insert a new drill bit into the clamping sleeve spline and twist it. If the rotation range exceeds 5mm, replace the clamping sleeve.


6. apply lubricating oil to all parts of repaired parts and all parts to be assembled.




Vi. assembly of impactor


1. put the lower end of the outer pipe up on the ground, put the small end of the bushing down into the outer pipe, and knock it in place with a copper rod.


2. stand the big end of the drill bit down on the ground, apply a layer of grease to the internal thread of the outer tube, put the big outer circle of the drill bit sleeve down, put the "O" ring on the snap ring, and clamp the snap ring on the small outer circle of the drill bit, and screw the drill bit, the drill sleeve and the snap ring into the outer tube.


3. put the outer tube with drill bit on the workbench, drive the valve seat into the inner cylinder with copper rod, put the piston into the cylinder, and push one piece into the outer tube from the upper end of the outer tube. And knock it in place with a copper rod.


4. put in the spring and check valve to see if the check valve moves freely.


5. apply a layer of grease to the internal thread at the upper end of the outer tube, and screw the rear joint into the outer tube.


6. poke the piston with a long rod to see if it can move freely.




VII. Common troubleshooting


Fault 1 Insufficient lubricating oil or premature wear or damage.


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


Troubleshooting: check the lubricating device, adjust the oiler, and increase the oil injection amount.



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


reason:


1. the air circuit is blocked.


2. the clearance between piston and inner and outer cylinders, piston and valve seat is too large.


3. the impactor is blocked by dirt.


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


Exclusion method:


1. check the air pressure and whether the air circuit is unblocked. Check valve is stuck.


2. disassemble the impactor, check the wear and replace the worn parts.


3. disassemble the impactor and clean all internal parts in the impactor.


4. disassemble the impactor and replace the piston or drill bit.




Fault 3 The drill bit and the clamping sleeve fall off.


Cause: the impactor did not rotate right when it was working.


Troubleshooting: hook up the fallen parts, and ensure right turning when drilling or lifting.