In various engineering construction and resource extraction projects, DTH drilling tools have become a key working tools widely used in drilling operations due tThis article outlines key operating specs for DTH drilling tools, including lubrication, unobstructed air passages, forward rotation, and water volume control, to aid maintenance, extend tool life, and ensure safe, efficient drilling.h efficiency and reliability. However, to ensure the stable and efficient operation of DTH drilling tools and extend their service life, a series of key precautions must be strictly followed during the drilling process. These seemingly cumbersome operating specifications are important guarantees for ensuring the normal operation of the DTH drilling tools and avoiding failures and accidents. So, what aspects should be noted when using DTH drilling tools? This article will provide a detailed introduction for you.
Before introducing the precautions, let's first understand what DTH drilling tools are.
I. Introduction to DTH Drilling Tools
DTH drilling tools are the core drilling tools in the rock-drilling machinery field. They mainly consist of a DTH hammer, a DTH drill bit, a DTH drill pipe, etc., and are widely used in mining, tunneling, quarrying, hydropower projects, and other fields. Their core function is to achieve efficient drilling in rocks through the high-frequency rock-breaking impact principle, which is especially suitable for engineering scenarios with high requirements for drilling depth and verticality.
II. Precautions During Drilling
1. Maintain Sufficient Lubrication
The piston inside the DTH hammer operates at a very high frequency, and the components are highly coordinated. In a high-intensity working environment, insufficient lubrication will lead to serious consequences. Without sufficient lubrication, the friction between the piston and other components will increase sharply, generating a large amount of heat, which may lead to component adhesion, seizing, or even cracking, ultimately rendering the entire part scrapped. This not only causes economic losses but also seriously affects the project's progress.
To ensure good lubrication, it is crucial to select the appropriate lubricating oil according to different seasons. In summer, when the temperature is high, the fluidity of the lubricating oil will be relatively enhanced. Therefore, No. 20 machine oil is suitable, as it can maintain good viscosity in high-temperature environments and provide continuous and effective lubrication protection for the DTH drilling tools. In winter, when the temperature is low, the viscosity of the lubricating oil will increase. Then, No. 5 - 10 machine oil or No. 5 spindle oil should be used. These lubricating oils have a low freezing point and good low-temperature fluidity, which can smoothly penetrate all parts of the DTH drilling tools in cold environments to play a lubricating role.
2. Keep the Air Passage Clean and Unobstructed
The DTH hammer is one of the core components of DTH drilling tools, and its normal operation depends on a clean and unobstructed air passage system. Before screwing the hammer onto the drilling rig, the joint hole must be temporarily blocked. This simple operation can effectively prevent foreign objects from the outside. Once these foreign objects enter the DTH hammer, they may block the air passage, affect the normal operation of the hammer, and even cause wear and damage to the internal precision components.
Similarly, before connecting the drill pipe to the hammer, the hole inside the drill pipe needs to be blown clean first. During use, the inside of the drill pipe may retain rock powder, debris, and other impurities generated during previous drilling. If these impurities are not cleaned up before connecting to the hammer directly, these impurities will enter the hammer under the drive of the airflow, which will also seriously affect the air passage system and the normal operation of the hammer.
3. Don’t Stop Air Supply First When Stopping Drilling
In the operation process of DTH drilling tools, there are strict requirements for the operating sequence when stopping drilling. The air supply should not be stopped first. This is because during the drilling process, the DTH drilling tools are in a high-speed rotating and impacting working state, and a large amount of rock powder will be generated between the DTH drill bit and the rock. If the air supply is stopped first, the airflow inside the DTH drilling tools cannot discharge these rock powder out of the hole in time, and the rock powder will accumulate.
When the DTH drilling tools are restarted, the accumulated rock powder will increase the resistance of the DTH drilling tools, and may even cause the DTH drilling tools to get stuck, resulting in serious equipment failures and safety accidents. Therefore, the correct operation method is to stop the rotation and advancement of the DTH drilling tools first when stopping drilling, and then stop the air supply after the rock powder in the hole is fully discharged.
4. Keep the DTH drilling tools Rotating Forward All the Time
The drill pipe and hammer of DTH drilling tools are connected by threads, and both are in right-hand thread structures. This design determines that the DTH drilling tools must always keep rotating forward during operation. If the DTH drilling tools are reversed during operation, the threaded connection part will gradually loosen, and may eventually lead to the DTH drilling tools falling into the hole. Once a hole-falling accident occurs, it will not only cause the loss of the DTH drilling tools but also seriously damage the drilling operation, and may even lead to casualties and property losses.
The same attention should be paid when disassembling the drill pipe. The drill pipe in the hole is not allowed to be reversed, otherwise, it will cause the drill pipe to loosen in the hole, increasing the difficulty and risk of fishing. Only by strictly following the principle of keeping the DTH drilling tools rotating forward all the time can the connection of the DTH drilling tools be ensured to be firm, and the safety of the drilling operation be guaranteed.
5. Control the Water Volume Appropriately
When performing wet rock-drilling operations, the water volume passing through the hammer needs to be appropriately controlled. If the water volume is too small, it cannot effectively suppress the flying of rock powder, resulting in a poor working environment and increasing the wear of the DTH drilling tools. If the water volume is too large, it will form mud, which will not only reduce the drilling speed but also hurt the service life of the DTH drilling tools. Generally speaking, it is advisable to control the water volume to a level where neither dry rock powder nor mud is formed.
It should be particularly noted that although water injection can improve the working environment to a certain extent, it does not substantially help to increase the drilling speed and extend the service life of the DTH drilling tools. Therefore, in wet rock-distilling operations, the water volume should be reasonably controlled to ensure a certain dust-reducing effect and avoid negative impacts on the DTH drilling tools and drilling operations due to improper water volume.
6. Pay Attention to the Diameter Change When Replacing the DTH Drill Bit
Previously we introduced how to reasonably determine the diameter size of rock drill bits? Of course, the DTH drill bit will inevitably wear during use, and its diameter will gradually become smaller. When the DTH drill bit is worn and the hole is not yet completely drilled, a new DTH drill bit should not be used for replacement. This is because the diameter of a new DTH drill bit is usually larger than the drilled hole diameter. If a new DTH drill bit is directly replaced, there will be large friction between the new DTH drill bit and the hole wall during the drilling process, which is likely to cause a drill-jamming accident. Once drill jamming occurs, it will not only force the drilling operation to be interrupted but also cause serious damage to the DTH drilling tools, increasing maintenance costs and operational risks.
When replacing the DTH drill bit, the wear condition of the DTH drill bit and the hole diameter must be carefully checked, and a DTH drill bit with an appropriate diameter should be selected for replacement to ensure a reasonable fit clearance between the DTH drill bit and the hole diameter and avoid drill-jamming and other problems caused by improper size.
III. Conclusion
In conclusion, each precaution during the drilling process of DTH drilling tools has its profound principle and important significance. Only by strictly following these operating specifications can the normal operation of DTH drilling tools be ensured, the efficiency and quality of drilling operations be improved, the service life of the DTH drilling tools be extended, and the smooth progress of engineering construction and resource extraction projects be guaranteed. Every person engaged in the operation and maintenance of DTH drilling tools should keep these precautions in mind and strictly implement them in actual work.
