With the rapid development of machinery and hydraulic equipment technology, hydraulic tunneling jumbos and rock drills are developing towards large size, automation, fully hydraulic, high-impact power, and large torque. Impact power, rotary torque, rock drilling propulsion speed, and hydraulic system pressure of this type of rock drilling equipment are greatly increased, which not only greatly improves the production efficiency of rock drilling operations but also reduces production costs. Now, hydraulic tunneling jumbos have been widely used in foundation engineering construction, highway, railway tunnel excavation, slope support, large and medium-sized open-pit and underground mines, quarries, water conservancy, and hydropower engineering, national defense engineering construction, and many other projects in the rock driving, mineral resources mining, anchor anchoring and stone mining fields. With the development of drilling and blasting technology, hydraulic tunneling jumbos have increasingly shown their superiority in engineering construction, and their usage has continued to increase. Demand for hydraulic rock drilling tools is increasing and performance and quality of rock drilling tools are required. Among them, drill rod of hydraulic tunneling jumbo is one of main supporting tools used in the hydraulic tunneling jumbo and consumes a lot in tunneling.
What is a drill rod for hydraulic tunneling jumbo?
Hydraulic tunneling jumbo is a kind of engineering machinery that integrates drilling, excavation, loading, transportation, and other functions. The drill rod is an essential component of the hydraulic tunneling jumbo. It serves as the connection between the drill bit and the hydraulic tunneling jumbo.
Features of drill rod for hydraulic tunneling jumbo
1. Thread sizes at both ends of drill rod are different, big end is connected to the equipment, and small end is connected to drill bit.
2. Most of drill rods are made of hexagonal hollow steel, and less circular hollow steel is used.
3. According to internal and external thread types, it is divided into MF rod and extension rod.
Force analysis of drill rod for hydraulic tunneling jumbo
Axial compressive and tensile stress
During rock drilling, impact force is applied to the shank adapter by a high-frequency, high-power hydraulic rock drill piston, which is transmitted to drill rod through threaded end of shank adapter.
Then to rock drill bit through drill rod, and finally, impact force is applied to the rock by rock drill bit , and rock generates a reaction force and transmits it to drill rod through rock drill bit. Therefore, drill rod is born to axial compressive and tensile stress during drilling.
Bending stress
Drill rod is a slender rod. Drill rod is not straight, weight of drill rod, axial propulsion force, and impact force of rock drill may cause bending deformation of the drill rod, resulting in non-linear transmission of impact energy, so that the drill rod is subjected to bending stress during the rock drilling process.
Torsional stress
Rock drilling tools (shank adapter, drill rod, coupling sleeve, rock drill bit) are driven and rotated by rotary part of rock drill during drilling. Drill rod should overcome various rotational resistances during rotation, so drill rod is born to torsional stress during drilling.
In addition, in drilling, there is collision and friction between drill rod and hole wall, and rock slag. There is a high-pressure water medium in a hole of drill rod, and this water is used locally from a water source in the mine, which is strong in acidity and alkalinity and has a strong corrosive effect on the surface of drill rod and wall of core hole.
In the context of the stress conditions experienced by drill rods for hydraulic tunneling jumbos, what characteristics does it need to have?
Characteristics of drill rods for hydraulic tunneling jumbos
High intensity: hydraulic tunneling jumbo drill rods must possess a high level of intensity to endure the shocks, vibrations, and pressures encountered during the drilling process.
High rigidity: to ensure the linearity and stability of drilling operations, drill rods must possess high rigidity.
Wear resistance: considering the extended periods of operation in harsh and abrasive environments, it’s crucial for the drill rod to be highly wear-resistant to withstand the wear and tear it will inevitably encounter.
Corrosion resistance: to prevent rust and corrosion, the material used for the drill rod must have excellent corrosion resistance, particularly given the potential exposure to moisture and corrosive substances.
These characteristics collectively ensure the longevity, efficiency, and reliability of drill rods used in hydraulic tunneling jumbo applications.
Production process of drill rod for hydraulic tunneling jumbo
Production process of drill rod for hydraulic tunneling jumbo is hollow steel inspection→ cutting to length → upsetting forging rod threaded end →processing thread. In production, medium-frequency induction heating and infrared thermometer are used to precisely control the initial forging temperature to avoid overburning and overheating.
In the scope of modern mining and underground engineering construction, hydraulic tunneling jumbos are undoubtedly a critical piece of equipment. The pivotal role of the drill rod cannot be understated. It extends far and wide in the mining, highway construction, railway engineering, and construction, et al. The importance of the drill rod lies in enhancing drilling efficiency and minimizing equipment failure rates. With the relentless advancement of science and technology, the performance of hydraulic tunneling jumbo drill rods will continue to evolve, affording engineers and miners a more dependable and efficient toolset to facilitate future engineering construction and mining endeavors.
