Types of Self-Drilling Rock Bolt Drill Bits and Applicable Geological Conditions

Time:2024-01-17From:sinorock View:

Introduction

Self-drilling rock bolts play a crucial role in various construction projects, combining drilling, grouting, and anchoring functions. At the heart of this innovative technology lies the drill bit, an indispensable component that determines the success of the self-drilling process. This article delves into the types of self-drilling rock bolt drill bits and their applications in different geological conditions.

self drilling rock bolt system

The Significance of Drill Bits

The self-drilling capability of these bolts is attributed to specially designed drill bits made from robust materials like 42CrMo, a medium carbon tempering type low alloy structural steel. These materials ensure the drill bits can withstand drilling forces and effectively penetrate rock formations. Unlike traditional drill bits, the self-drilling rock bolt bits are disposable, eliminating the need for replacement and simplifying construction methods.

rock bolt drill bits

Drill Bits Processing Technology

Self-drilling hollow bolt bits undergo either casting or machining processes, contributing to their durability and efficiency in various applications.

Types of Drill Bits

Hardened Drill Bits

a. Hardened Cross-cut Drill Bit (EX)

Features:
- Cross blade structure with rotating direction on the cutting edge.
- Differentiated water hole configurations for enhanced performance.

Applicable Geological Conditions:
- Soils and soft rocks, sandy soils, chalky soils, alluvial sandy soils, compacted fills, hard dense loess, gravel, pebbles, natural grading gravels, soft marl, and soft rocks (strong weathering degree).

Best Performance:
- Mudstone, gravel soil, chalk soil, lime soil, calcareous clay, artificial fill, soft mudstone.

Hardened Cross-cut Drill Bit

b. Hardened Button Drill Bit (ES)

Features:
- Spherical teeth on the flat surface for increased drilling efficiency.

Geological Conditions:
- Soils and soft rocks, sandy soils, chalky soils, alluvial sandy soils, chalky clay, compacted fill, hard dense loess, gravel, pebbles, natural grading gravel, soft marl, and soft rocks (strong weathering degree).

Best Performance:
- Crushed formation, soft sandstone, limestone, gravel, soft rock formation.

Hardened Button Drill Bit

Clay Drill Bit

Features:
- Double-layer cross bits with backflush grouting holes.
- Increased cutting edge wear resistance through casting and heat treatment.

Applicable Geological Conditions:
- Sandy soil, chalky soil, alluvial sandy soil, silt, chalky clay, sand with gravel, fill, dry loess, loess with gravel, and gravelly firm soil.

Best Performance:
- Clay, soft soil, sandy soil, gravel, mixed fill.

clay_bit

Carbide Drill Bits

Tungsten Carbide Cross-cut Drill Bits (EXX)

Features:
- Cross blade structure with welded straight alloy bar.

Applicable Geological Conditions:
- Soft rock, hard clay, medium dense shale, marl, chalk, poorly cemented conglomerate, soft limestone, shell limestone, and medium hard rock (strongly weathered).

Best Performance:
- Soft to medium hard rock, gravel mixed with boulders, rock formations with developed cracks, and unreinforced concrete.

Cross Carbide Drill Bits

Tungsten Carbide Button Drill Bits (ESS)

Characteristics:
- Welded with ball-tooth alloys in three-flap or four-flap structures.
- Enhanced drilling efficiency through outermost ring exposure.

Applicable Geological Conditions:
- Soft rock, hard clay, medium-density shale, marl, chalk, poorly cemented conglomerate, soft limestone, shell limestone, medium-hard rock (medium weathering degree), and hard rock (strong weathering degree).

Best Performance:
- Soft to medium hard weathered rock formations, boulders, gravel, such as mudstone, schist, volcanic rock, etc.
Carbide Button Drill Bit

Drill Bit Structure

Different drill bit structures impact drilling efficiency during construction. Taking the cross alloy drill as an example, it comprises five parts: cross blade, upper and lower slag discharge grooves, neck of the trousers, and flushing or slurry hole. Understanding parameters like edge angle and clearance angle is crucial for optimizing drilling speed and wear resistance.

Common Problems and Solutions

Hardened Drill Bits

a. Drill Bit Broken

Cause Analysis:
During the heat treatment process, crack defects or structural design flaws may arise.

Solution:
Strictly control the heat treatment process or optimize the structural design.

b. Low Drilling Efficiency or Short Service Life

Reason Analysis:
Unreasonable structural design or poor heat treatment hardness control.

Solution:
Strictly control the heat treatment process or optimize the structure design of the drill bit.

Carbide Drill Bits

a. Damaged Alloy Teeth

Cause Analysis:
Cracks in welding or improper operation.

Solution:
Rework soldering.

b. Shorter Service Life

Reason Analysis:
Unreasonable structural design of alloy drill trousers.

Solution:
Optimize the structural design.

Rock Bolt Drill Bit and Applicable Geological Condition

Conclusion

In conclusion, understanding the types of self-drilling rock bolt drill bits and their applications in diverse geological conditions is crucial for successful construction projects. The article has provided insights into the features, geological conditions, and best performances of various drill bits, along with their structures and common problems with solutions. For further inquiries or professional assistance, please feel free to contact Sinorock via sinorock@sinorockco.com.

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