When drilling in complex geological formations, it's essential to select appropriate drilling parameters based on the principles of low rotational speed, reduced feed pressure, and high air flow velocity. The rock's hardness and stability must be assessed during the drilling process, as factors like moisture content significantly influence the drilling rate. In cases where the formation is especially loose or fractured, it's crucial to lower both the feed rate and pressure, while frequently performing slag removal to prevent blockages.
During actual construction, several key points should be carefully observed:
1. Before starting the drilling operation, ensure that all downhole components—such as the impactor, heel drill, casing, and casing shoe—are securely connected. Check the flexibility of the eccentric drill and confirm that the ventilation system is functioning properly.
2. While drilling, monitor the casing’s stability and the amount of cuttings being removed from the hole. After every 0.3 to 0.4 meters of drilling, perform a strong air blow to clear the hole. Control the lifting height of the central drilling tool precisely to achieve effective cleaning. Avoid forcefully lifting the tool during the drilling process to prevent damage or inefficiency.
3. When the drilling is complete or the central drill needs to be replaced, first clean the hole thoroughly, removing any residual material from the bottom. Then stop the rotation and slowly lift the central drill, applying just enough force to raise it slightly. Ensure that the back of the eccentric bit makes contact with the front end of the casing shoe. Next, reverse the drill at a low speed and slowly lift the central drill. Once smooth upward movement is achieved, it indicates that the eccentric bit has been retracted, and the tool can then be lifted normally until fully extracted. Be cautious during the reversal to avoid tripping the drill.
4. In some cases, excessive cuttings may accumulate at the bottom of the hole, causing the eccentric bit to become stuck due to the debris. If this occurs and initial attempts fail, use the compressor to clean the hole again, operate the down-the-hole hammer briefly, and then resume the lifting process.
DTH (Down-The-Hole) hammers combined with pipe drilling technology offer an effective solution for drilling through challenging tunnel structures in engineering projects. Eccentric heel drills are particularly well-suited for complex formations because of their unique design and reliable performance, providing a solid technical foundation. The range of heel drill specifications used in construction continues to expand and improve, offering greater versatility and efficiency in various applications.
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**Label:** heel drill bit
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