Performance Requirements of Steel for Heavy-duty Rock Drilling Tools

Table of Contents

The rapid development of rock drilling equipment promotes the continuous development of rock drilling tools. As the application of rock drilling tools becomes more and more extensive, the market has higher and higher requirements for the performance of rock drilling tools. Large heavy-duty rock drilling machines such as hydraulic rock drilling rigs have a large request for drilling tools during rock drilling, and this kind of rock drilling tools generally called heavy-duty rock drilling tool.

What is a heavy-duty rock drilling tools?

rock drilling tools

Rock drilling jumbos need to be equipped with heavy-duty rock drilling tools. Heavy-duty rock drilling tools generally refer to heavy-duty rock drilling rods with a cross-sectional distance of 28, 32, and 35mm hexagonal and a diameter of 38, 45, and 51mm, as well as their supporting shank adapters, coupling sleeves, and rock drill bits. The length of the drill rod is 3-6m, and the weight of a single piece is more than 20 kg.

Features of heavy-duty rock drilling tools

It has a large section, a long length, a single piece of heavyweight, high impact resistance, fast rock drilling speed, and high energy utilization.

Classification of heavy-duty rock drilling tools

Unlike rock drilling jumbos, heavy-duty rock drilling tools have the following categories:

1. The main specifications of rod drilling tools for open-air and mining operations are D38, D45, and D51mm, with two lengths of 3050 and 3660mm. There are a small amount of B32 (hexagonal), D38mm extension rods, and MF rods with extension sleeves. The length of the extension rod for mining operations is shorter, such as 1220, 1525, 1830mm, and so on.

2. Drilling tools for roadway operations

The main specifications of rock drilling tools are B28, B32, and B35mm, and the length of drill rods for large-section roadway drilling jumbos is 3700, 4305, 4915, and 5525mm, and the length of drill rods for small-section roadway drilling jumbos is 2475, 3090, 3700, 4305mm.

With the increasing trend of large-scale and heavy-duty rock drilling tools, the requirement for high-quality heavy-duty rock drilling tools in the market is also increasing.

The structure of a high-quality drilling tool is the main factor that decides its quality and service life. Although in the production process, every step can affect the structure and properties of the rock drilling tools, affecting its quality and service life, the most basic is the steel used for the rock drilling tools. For example, the steel used in heavy-duty rock drilling tools requires good strength and toughness to ensure its wear resistance and impact resistance, and it also requires good processing performance and certain corrosion resistance. In response to this, we will share with you the performance requirements of steel for heavy-duty rock drilling tools.

Steels for heavy-duty rock drilling tools require specific performance requirements to ensure reliability and durability under high loads and harsh environments.

Performance requirements of steel for heavy-duty rock drilling tools

High strength

Steels for heavy-duty rock drilling tools require high strength and can withstand high pressure and heavy load. It is an important performance to ensure that the rock drilling tools will not be damaged or deformed under working conditions.

Good toughness

Since heavy-duty rock drilling tools may be affected by external forces such as shock and vibration during use, the steel used must have good toughness and be able to resist crack growth and fracture.

Excellent wear resistance

Steel for heavy-duty rock drilling tools requires good wear resistance to resist wear and abrasion during drilling or mining. It helps to increase tool life and performance stability.

Good corrosion resistance

Steel for heavy-duty rock drilling tools requires use in harsh working environments, such as high temperature, high pressure, acid-base medium, etc. Therefore, steel requires good corrosion resistance to prevent corrosion and damage.

Proper processing performance

Steel for heavy-duty rock drilling tools requires good processing properties to manufacture and process rock drilling tools. It includes enforceability, weldability, machinability, etc.

These performance requirements may vary based on specific applications and operating conditions. In practical applications, there is a general tendency to select special steels suitable for particular work requirements to meet the performance needs of heavy-duty rock drilling tools.

Due to different resources, manufacturing processes, and technologies in different countries, the steel used for heavy-duty drills is not the same. It can include carbon rock drill steel and alloy rock drill steel. And carbon rock drill steel is getting harder to keep up with demand in people’s practice. So, in the process of looking for new steel grades, alloy rock drill steel was born, and this is what we are going to share.

As we all know, the rock drilling tools consists of four parts: the drill bit, the drill rod, the shank adapter, and the coupling sleeve. According to the different service conditions of each part of the rock drilling tools, the performance requirements for alloy steel are also different. Since the coupling sleeve is relatively simple, we will not introduce its performance requirements too much here. The performance requirements of the drill bit, drill rod, and shank adapter are as follows.

Performance requirements for the drill bit

The composition of the rock drill bit is to inlay or weld the rock drill carbide on the alloy steel carrier. In the process of working, the drill bit is in direct contact with rock, which needs to bear the cyclic load of tension, extrusion, torsion, bending, and other loads, as well as the corrosion of rock, mineral water, and other media, so it is the most easily damaged part of rock drilling tools. Because of this, its performance requirements are mainly high enough surface hardness, good strength and toughness matching, good processing performance, and corrosion resistance.

Performance requirements for drill rods

In the process of rock drilling, the heavy-duty drill rod mainly relies on the connection between the external thread of the threaded connection drill rod and the internal thread of the coupling sleeve or the drill bit, drilling holes through the rotary impact of the rock drill. During rock drilling, the drill rod mainly bears the combined action of the high-frequency percussion of the rock drill piston and the propeller thrust. At the same time, at the moment of rock drilling, the rock also produces a reaction force to the drill rod through the drill bit. Therefore, the drill rod bears axial high-frequency compression pressure and high-frequency tensile stress in the rock drilling process, as well as torsional and bending stress. This requires the performance of the drill rod to meet higher fatigue strength, impact toughness, corrosion resistance, lower notch sensitivity, and crack growth rate.

Performance requirements for shank adapter

The shank adapter directly bears the high-frequency impact of the rock drill, so it works under high speed, high frequency, and strong impact conditions. Therefore, it is also a key part of the hydraulic rock drill. According to the working conditions of the shank adapter, its performance requirements are mainly that its core should not only have good toughness but also have enough strength to make it have high impact contact fatigue resistance. At the same time, because the shape of the shank adapter has particularity and complexity, the material selection of the shank adapter must have a certain hardenability to balance the bending fatigue strength.

Generally speaking, steels for heavy-duty rock drilling tools are selected according to specific standards and specifications to ensure that they meet the expected working conditions and performance requirements. Therefore, when people face more geological conditions, there will be more performance requirements for steel for heavy-duty rock drilling tools. Only continuous comprehensive control from smelting, rolling, forging, machining, and heat treatment can improve the quality level of steel for heavy-duty rock drilling tools.

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