6 Fixes: DTH Drill Opening Mistakes & Rod Skew/Sticking
The скважинный (DTH) бур adheres to the core principles of starting with low parameters, precise calibration, slow drilling with light pressure and dust removal priority, covering the entire processes of hole opening, normal drilling and completion. It also ensures equipment protection and pre-avoidance of malfunctions, and is suitable for mainstream mine operation scenarios such as blasting holes and support holes.
1. Pre-Drilling Equipment & Accessory Calibration
- Coat hammer/bit/drill rod threads with special compound, fasten to 80-120N·m (no slipping/loosening); drill rod straightness ≤0.5‰, wear ≤3% of outer diameter (reject bent rods).
- Air compressor no-load test: stable pressure 0.4-0.6MPa, air volume (90mm≥3m³/min, 115mm≥5m³/min, 140mm≥7m³/min); hydraulic system pressure 18-22MPa (no leakage/instability).
- Dust removal system test: dry dust removal suction ≥12kPa, wet dust removal water pressure 0.2-0.3MPa (no pipeline blockage).
2. Precise Drill & Hole Positioning
- Align hole position (deviation ≤5cm); lock crawlers/extend outriggers for level fuselage (level gauge ≤0.2°), wheeled drill ground contact area ≥80% (no overhead operation).
- Calibrate drill rod with verticality meter/laser benchmark: vertical hole deviation ≤0.5°, inclined hole deviation ≤0.3°; fix drill frame after calibration (no displacement).
- Clear floating rocks/debris within 3m of hole (clean height ≥drill frame height); set up protective enclosures for slope/high-altitude drilling.
3. Standard Open-Hole Operation Sequence (0-1m Depth)
Strictly follow: Air Supply → Rotation → Impact (forbid impact first to avoid hammer pressure damage)
- Purge hole mouth for 3-5s (stable air pressure 0.4-0.6MPa); start rotation at 10-20r/min (30%-40% rated speed).
- Turn on hammer light impact mode (800-1200 times/min); complete the whole sequence without reverse operation.
4. Core Parameter Control for Open-Hole Drilling
- Propulsion force: 30%-50% rated (90mm≤5kN, 115mm≤8kN, 140mm≤12kN), inching pressurization (single stroke ≤5cm, no continuous high thrust).
- Air pressure/volume: keep pressure 0.4-0.6MPa (match volume to aperture); for weathered rock/soil, adjust to +1-2m³/min volume, -0.1MPa pressure (no slag accumulation).
- Real-time monitoring: calibrate verticality every 20cm (adjust drill station/frame immediately if deviation ＞0.5°); dust removal synced, hole mouth rock powder ≤5cm (no mud formation for wet dust removal).
5. Deviation & Sticking Prevention (Source Control)
- Deviation prevention: drill frame guide rail wear ≤0.2mm, drill rod straightness test every 500m; hard rock drilling (rotation ≤10r/min, propulsion 30% rated); weathered/loose layer drilling with casing (5-10mm larger than bit, depth ≥1m).
- Sticking prevention: purge slag for ≥10s if discharge is slow (forbid drilling with slag accumulation); stop immediately if hydraulic pressure surges ≥25MPa (only rotation+air supply, slow rod retraction); reject mixed drill rods/frequent hammer start-stop; backfill gravel+clay 0.5m above collapse position for hole collapse.
6. Emergency Treatment for Slight Deviation/Sticking
- Slight deviation (0.5°-1°, depth ≤1m): retract rod to 0.2m of hole mouth, offset drill rod 0.3°-0.5° in reverse direction, drill slowly to original depth with inching pressure+low-speed rotation (re-calibrate verticality then resume).
- Slight sticking (rod rotatable, unpropellable/non-retractable): turn off hammer, keep rotation 10-15r/min + high pressure 0.7-0.8MPa, slow inching retraction + slag purge; clean jammed rock then re-drill.
- Forbidden operations: no forced correction for deviation ＞1°/depth ＞1m (backfill to ground then re-drill); no forced pulling/pressurization for non-rotatable stuck rod (avoid fracture).
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