In roadway drilling, enterprises usually choose appropriate equipment according to roadway size, rock compressive strength, rock compactness, and integrity. Rock drilling tools are also essential tools in rock drilling. Therefore, choosing the right rock drilling tools can improve excavation efficiency, reduce costs, and ensure operation safety.
How to choose rock drilling tools for mine roadway excavation?
Understand working conditions
First of all, it is necessary to understand the working conditions of the tunnel, including the length, width, height, rock type, geological conditions, ventilation conditions, etc. These factors will directly affect the selection of rock drilling tools.
Choosing the appropriate type of rock drilling tools
- Select the appropriate type of rock drilling tools according to the working conditions. For example, for hard rock, you need to choose a rock drilling tool with high strength and wear resistance; for soft rock, it is possible to select a rock drilling tool that is light and easy to operate.
- Consider the drilling speed and drilling depth of rock drilling tools. Choose rock drilling tools that meet your excavation needs to improve work efficiency.
- Consider the reliability of rock drilling tools. Choose rock drilling tools that have passed strict quality testing to ensure stable work in harsh mining environments.
Thread
Most rock drills are connected with 38 mm threads, that is, T38 or R38. The choice of T or R threads is mainly based on the rock conditions and work requirements.
① R thread. It is a tighter connection, which reduces the loss of energy in the process of energy transfer and also reduces the heat generated by loosening. From another point of view, the wave thread is not easy to disassemble. If the equipment can provide a large enough propulsion and rotation force, T thread will be a better choice.
②T thread. It has a higher pitch and a larger contact surface, which is wear-resistant and easy to disassemble.
Shank adapter
Shank adapter has an important role in rock drilling tools, mainly transmitting torque, propulsion pressure, and impact pressure. It should be able to withstand not only the impact energy but also the rotational torque caused by friction against the rock while drilling. The selection of shank adapter is basically based on the model and specification of rock drill, and the length of shank adapter should be considered in conjunction with the propulsion beam and the length of drill rod. Since the shank adapter is closely connected to rock drill, the internal structure of the drill already determines the diameter of shank adapter, the size of the rotary spline, and the location of the drain hole. At the same time, it is important to use a highly reliable shank adapter to avoid damage to the internal structure of rock drill due to abnormal failure of shank adapter.
Coupling sleeve
Coupling sleeve is mainly to connect the shank adapter and drill rod and make the end faces of drill rod and shank adapter can be connected face to face to transfer energy effectively.
Drill rod
As the most important part of the whole rock drilling tools, drill rod is mainly used to transfer energy during the drilling. In underground roadway drilling, hexagonal drill rods are used in most cases. Compared with the round drill rod, hexagonal drill rods are made of more material, have higher fatigue strength, and are more rigid throughout. If the diameter of the end face of impact piston is closer to the diameter of the end face of shank adapter, the more effective energy transfer will be.
The selection of drill rod mainly considers 4 points.
①Thread for connecting shank adapter.
②Determining the length of drill rod by the length of advancing beam.
③Choose the correct diameter of drill rod so that the drill rod can rotate freely and have a reasonable annular gap to achieve the effective slagging effect.
④Consider the above factors to determine the thread of the end of rock drill bit.
Rock drill bit
As the end point of contact with the rock, it is particularly important to choose rock drill bit to be able to use the effective energy to break the rock and reduce the reaction force. It is the main reason why there are more rock drill bits and models than other rock drilling tools.
The selection of rock drill bit is mainly based on different application conditions, such as rock conditions and drilling requirements, through which the appropriate carbide column diameter, shape, protrusion height, and edge tooth angle. Usually, the carbide button includes conical button, parabolic button, and ogive button, different button shapes have different rock drilling efficiency. Choosing a carbide button mainly considers the requirements of drilling speed, drilling accuracy, and service life of rock drill bit.
Concerned about the mechanical properties of rock drilling tools
Hardness: the hardness of rock drilling tools is an essential indicator for selection. Rock drilling tools with high hardness can break rocks better and improve drilling efficiency. However, too high hardness may cause premature wear of rock drilling tools.
Toughness: rock drilling tools require a certain degree of toughness to withstand shock and vibration during drilling. Rock drilling tools with good toughness can better adapt to the harsh working environment of mines.
Corrosion resistance: choose a rock drilling tool with good corrosion resistance that can maintain its performance and service life in a humid and corrosive environment.
Consider economic factors
Under the premise of meeting the requirements of working conditions, choosing reasonably priced rock drilling tools can reduce the overall cost. At the same time, considering the cost of maintenance and replacement, choosing rock drilling tools with long service life and simple maintenance can improve economic benefits.
In short, we should consider many factors to choose the right rock drilling tools for mining roadway excavation. Only by comprehensively considering these factors and selecting the appropriate type of rock drilling tool can excavation efficiency be improved, costs reduced, and operational safety.
