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.

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

1. 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.

2. 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.

3. 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.

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.

Only reasonable structural design, good production technology, and machining quality can ensure long service life of drill rods. With the continuous innovation and progress of science and technology, the number of hydraulic tunneling jumbos used in underground construction projects will continue to increase, which is also a good opportunity for drill rod manufacturers. Therefore, development of high-performance, stable quality, long service life, and cost-effective drill rod for hydraulic tunneling jumbo is not only a market demand but also a development trend.