Rock drilling engineering is one of the essential links in mining, tunnel excavation, and other construction fields. Rock drilling tools are critical tools in rock drilling projects. Their drilling efficiency and service life have a vital impact on the progress and quality of the entire project. However, the efficiency of rock drilling tools drilling is affected by multiple factors. If deviations occur during the drilling process, it will affect the drilling effect. Understanding these factors and optimizing on this basis can effectively improve rock drilling efficiency and extend the service life of rock drilling tools.
What are the factors affecting drilling of rock?
Rock mass geological conditions
Most influential factor in drilling deviation is actual drilling, especially when drilling in rock formations with complex geological conditions. Generally, degree of drilling deviation is proportional to drilling depth. Experience has shown that drilling angle of a rock drill bit to rock layer is critical. When this angle is less than 15°, drilling direction of a rock drill bit is inclined at an angle parallel to plane of rock junction. Conversely, if a rock is of uniform texture, there will be little or no deviation in drilling.
Rock drill bit
Rock drill bit structure and shape also affect drilling deviation. In drilling, regardless of rock drill bit shape, to obtain the best drilling straightness, the worn bit must be reground in time to restore shape of carbide button and maintain carbide’s integrity. In particular, when grinding spherical on the edge, not only spherical, but also steel of skirt body should be ground, and the whole side of skirt body should be ground down, instead of only grinding off steel body near spherical root.
Drill rod
If other drilling conditions are same, the larger diameter of drill rod, the higher straightness of drill hole. In addition, the large-diameter drill rod can increase rigidity of rock drilling tools, and ensure that rock drill bit does not swing, which is conducive to smooth discharge of cuttings from hole. Therefore, a guide rod with a diameter larger than drill rod is usually installed at the front of rock drilling tools to drill holes with a diameter larger than 127mm and is directly used to ensure that the hole is drilled with high straightness.
Another way to reduce drilling deviation is to use a center-fluted retract guide bit. Diameter of skirt body is roughly the same as diameter of rock drill bit head, which maximizes guiding performance of rock drill bit in blast hole. Center-fluted retract guide bit is an improved drill bit based on the standard drill bit, which can achieve better drilling straightness. If a guide rod is used, drilling straightness will be ideal.
Other factors
Impactor specifications, drill bit and drill pipe design, etc.
In addition to above points, many other factors affect drilling. Although it is impossible to completely avoid drilling deviation, we can reduce the deviation through some methods so as not to affect progress of entire rock drilling project.
Methods to reduce drilling deviation of rock drilling tools
- Use a drill rod with high hardness, good rigidity and straightness, and make diameter of drill hole close to diameter of drill rod as possible.
- Use new tubular guide rod to reduce probability of drill rod breaking.
- Use rock drilling equipment with high drilling accuracy to reduce drilling deviation.
- Ensure correct propulsion force, increasing rotation speed of rock drilling tools can also reduce drilling deviation.
- It can also reduce deviation by drilling shallow holes in sections.
Tips for improving drilling efficiency of rock drilling tools
To optimize the efficiency of rock drilling tools, you can refer to the following:
- Select Appropriate Rock Drilling Tool Material: Choose the rock drilling tool material that best matches the specific rock types and engineering requirements, ensuring that it provides optimal performance and durability.
- Choose the Right Drill Bit Shape: Different drill bit shapes can impact the drilling cross-section. Select the appropriate drill bit shape based on the project’s specific engineering requirements to achieve the desired results.
- Ensure Adequate Air Pressure: Maintain sufficiently high compressed air pressure to enable the rock drilling tool to bore holes quickly and ensure effective removal of drill cuttings from the blast hole.
- Control Axial Thrust: Carefully manage the size of the axial thrust applied to the rock drilling tool, as excessive thrust can accelerate wear and reduce the tool’s efficiency.
- Optimize Work Scheduling: Arrange work times effectively to maximize the efficiency of rock drilling tools and minimize auxiliary operational time, helping streamline the drilling process.
- Swift Troubleshooting: Once a fault occurs, address it promptly to prevent any adverse impact on overall drilling efficiency.
- Enhance Drill Steel Quality: Utilize high-efficiency, long-life drill bits to reduce the frequency of drill bit replacements, thus improving drilling efficiency and reducing downtime.
- Employ Rock Drilling Rigs: Employ rock drilling rigs, which are hydraulic systems designed for rock drilling. This specialized equipment can significantly enhance drilling efficiency.
- Train Operators: Thoroughly train rock drill operators to ensure they possess the necessary skills for safe and efficient operation and maintenance of rock drills.
By following these guidelines and implementing these best practices, rock drilling projects can proceed more efficiently, resulting in enhanced performance, reduced downtime, and a lower environmental impact.
In summary, several factors influence the performance of rock drilling tools. To improve the drilling efficiency and service life of rock drilling tools, we should comprehensively consider these factors, rationally select and use rock drilling tools, and avoid or reduce excessive wear and consumption of rock drilling tools. In addition, for different rock types and engineering needs, specific analyses and adjustments need to be made based on actual conditions to achieve high quality, efficiency, and safety in rock drilling projects.
