Down-The-Hole Drilling Rigs


With the rapid development of social economy, the demand for mineral resources has increased year by year, so mining facilities have also received widespread attention. It mainly briefly explains the working principle and structure of down-the-hole drilling rigs, analyzes common faults of down-the-hole drilling rigs and corresponding solutions, and also analyzes the maintenance measures of down-the-hole drilling rigs in open-pit mines, in order to ensure the safety and efficiency of mining. run.

Analysis of common faults of down-the-hole drilling rigs

Failures that often occur during the drilling process mainly include: relatively severe swing of the drill frame and overload problems of the rotary motor, which will lead to abnormal drilling; damage to the rotary mechanism, reducer bearings, and gear teeth, etc. As a result, the rotary load is too large and the coupling fails, causing the rotary mechanism to be unable to operate; when the drill is severely stuck, the lifting device cannot lift properly; due to damage to the seal or wear of the outer ring of the bearing, the sealing effect is not good, resulting in joints Air leakage and pressure relief phenomenon; the drilling rig manipulator cannot clamp the drill pipe, mainly because the chuck is worn or the manipulator claws are deformed; the main cause of walking problems may be that the bearings of the reducer are damaged or the track joints are worn or the track Stretching, pressure relief of the track tensioning cylinder, etc.; failure of the connecting and unloading rod components may be due to misalignment of the upper and lower positioning sensors of the drill rod magazine, unsynchronization of the upper and lower manipulator cylinders, bending of the drill rod, etc.; impactor frequency generation Abnormality. The reason for this abnormality is that the assembly gap between the cylinder and the piston is unreasonable, resulting in the gap between the sleeve and piston being too small or too large.

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Working principle and structure of down-the-hole drilling rig


Hammer has two exhaust structures, namely center exhaust and side exhaust. This article mainly introduces the center exhaust impactor. The exhaust gas and part of the compressed air generated by the work enter the bottom of the drill hole through the middle hole channel of the drill bit. In the working state, the impactor piston continuously impacts the drill bit, providing a steady stream of impact energy to squeeze the rock, and the cylinder is not subject to impact load. The main working principle of the impact stroke is: at the beginning, the piston is in the extreme left position, and part of the compressed air enters the cylinder through the valve cover, pushing the piston to move. At this time, the spline groove of the bushing is closed, the pressure continues to rise, and the rear end hole of the piston leaves The pressure of the air distribution rod decreases, and then impacts the drill tail at high speed, and the impact stroke ends.

2. slewing mechanism

As one of the important working parts of the down-the-hole drilling rig, the rotary mechanism mainly transports compressed air and drives the rotation of the impactor. The main working parts of this structure are the rotary reducer, rotary machine and air supply gyrator, which are connected as a whole through couplings and bolts and fixed on the sliding plate of the drill frame guide rail.

3. Slag discharge system

The drilling process will produce a large amount of cuttings and dust. If the slag is not discharged in time, it will affect the drilling work. Currently, there are two methods: dry slag discharge and wet slag discharge. The dry slag discharge uses the action of compressed air to discharge rock debris, and the wet slag discharge uses the effect of Feng Shui mixture to discharge. The quality of the slag discharge system is related to the working effect and service life of the drilling tool.

3. Troubleshooting Countermeasures

1. Countermeasures during the drilling process

During the drilling process of down-the-hole drilling rigs in open-pit mines, the sound of the drilling rig should be monitored at all times to distinguish vibration and abnormal noise conditions. When dealing with loose rock formations and severe cuttings falling off, if the drilling speed changes significantly and rocks are falling off at the same time, you should stop immediately, lift the drilling tool out of the borehole, and remove it beforehand. The adjusted adhesive is placed in the borehole. The combined action of the pressure and the drill pipe will cause the adhesive to adhere to the loose borehole wall, ensuring the smooth progress of the drilling work. The most important thing to pay attention to in this link is the stuck situation of the drill. Once the stuck phenomenon occurs, it will have a huge impact on the drilling speed and even cause damage to related parts. For stuck drill faults, do not act too hastily, otherwise the fault will amplify, such as rupture of the rotary motor oil pipe, toothing of the rotary gear, damaged bearings, etc. It should move up and down slowly, alternating positive and negative actions.

2. Things to note when stopping and moving

During the process of drilling another hole position, the impactor can no longer provide air pressure at this time, and then stop the ventilator. The drilling tool cannot be rotated. The drilling tool cannot be lifted to the top at once. It should be allowed to rise slowly. Coordinate all links and do not change the sequence. If the gas supply system is shut down prematurely, the speed of lifting the drilling tool will be too slow, and the cuttings and ash layer will easily wrap the drilling tool, causing the drill to get stuck. Go to the corresponding drilling hole position, adjust the operating parameters before operating.

4. Maintenance of down-the-hole drilling rigs in open-pit mines

When loading and unloading drill pipes, the different rotating arms of the drill pipe manipulator should be structurally concentric and synchronized and should not be deformed; ensure that the rotation angle of the drill pipe magazine is uniform and accurate, and that too many objects should not be accumulated in the tray of the drill pipe magazine. Dust; it is necessary to ensure that the manipulator slips are sufficiently tightened. Once the slips are worn, they need to be replaced in time to prevent the drill pipe from falling on site and causing safety accidents; when disassembling the drill pipe, the unloading cylinder is stuck The claws should block the main and auxiliary drill pipes, and the air supply system cannot be opened at this time. When raising and lowering the drilling rig, the rope releasing speed of the wire rope should be smaller than the free falling speed of the drilling rig, otherwise the wire rope will become knotted. When the drill frame is lifted to the appropriate working position, it should be reinforced. Otherwise, the swing of the drill frame during drilling will cause the drilling angle to change, and the drilling quality cannot be guaranteed. For the rotary air supply system, in-shift inspections should be strengthened to avoid loosening of connections. Particular attention needs to be paid to the meshing of the gears in the reducer. Once abnormal noise occurs and the rotation is inflexible, work must be stopped immediately and a specialized maintenance team must be dispatched. Personnel are required to open and inspect the internal components to see if any parts are damaged. The axial runout of the hollow spindle should be within 0.8mm, and the axial runout of the gear should be within 0.3mm. If it exceeds the range, the relevant parts must be repaired in time. Tighten and adjust. When air leakage occurs in the air supply system, the sealing condition should be checked immediately, and the sealing rings and severely worn bearings should be replaced if necessary. Maintenance of wire ropes, sky wheels and ground wheels: During the drilling process, professional maintenance personnel should adjust the tightness of the wire rope. The drilling stroke is closely related to its tightness.

In short, when using down-the-hole drilling rigs, great attention should be paid to the use, management and maintenance of mining equipment. In this way, we can improve the technical level of domestic mining rock drilling equipment management, better utilize the effective life of mining equipment, continuously improve the comprehensive benefit level of mines through scientific management methods, ensure the safe and efficient production of mineral mining enterprises, and better Escort the energy saving and efficiency improvement of mining enterprises.

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