The Development of Drill Rod for Tunneling Jumbo

Table of Contents

Hydraulic tunneling jumbo is a high-efficiency rock drilling machine used in the construction projects such as the excavation of large underground metal mine roadway, tunneling, the construction of diversion caverns and underground plants in power station projects, and the drilling of anchor holes in underground rock formations. With the rapid development of science and technology and the continuous improvement of engineering needs, it plays an increasingly important role in various engineering projects. As an essential component of the tunnel drill jumbo, the drill rod’s drill rod performance and design directly affect the progress and quality of the project.

Requirements for rock drilling tools for tunnel drill jumbos

Tunneling jumbos usually use a drill set consisting of a single drill rod. The drill rods mainly include R32/R28-H25-R25, R32-H28-R25/R28, T38/R38-H32-R32 and T38/R38- H35- R32, etc. There are two ways of threaded connection of drill rod: casing connection and MF drill rod connection. As the drill rod is a slender rod, the shape of the rod is usually hexagonal, which has a larger cross-sectional area and better bending strength than a round rod.

MF rod

In terms of rock drill bits, the drill bits used for tunneling jumbos are mainly button bits with a diameter of 35-51 mm. The requirements for rock drilling tools in use are that the drill rod has high toughness and strength and has good wear resistance, the drill bit has a fast drilling speed and smooth powder discharge, the carbide button is wear-resistant, and it is not easy to get stuck.

rock drill bit

Development of drill rods for tunnel drill jumbos

In industrially developed countries, it is common to use tunneling jumbos in underground engineering construction. Therefore, famous international rock drilling tools manufacturers attach great importance to the research and development of improving the performance of rock drilling tools and have made significant progress in improving product material performance and structure. It can be said that in the two decades from the early 1980s to the beginning of this century, the structure of products have been improved at least three times, and each improvement brings about an increase in the performance of products.

extension rod

As we all know, the impact energy output by the rock drill drives the drill bit through the drill rod to drill into the rock. A drill rod is not only a component of rock drilling tools but also a carrier for transmitting rock drilling energy in the form of stress waves. In the process of energy transmission, the change of the cross-section of the drill rod and the surface or internal defects of the steel are the parts where the stress concentration occurs, and it is also the part that is easy to cause the drill rod to break. Theoretically, it is ideal to make a uniform rod without cross-sectional changes. However, since the drill rod must be connected through threads to form a drill tool set, changes in the rod cross-section are inevitable at the threaded area. The problem of how to reduce the stress concentration at the root of drill rod thread, especially the thread root at the end of the drill bit, has been paid attention to by rock drilling tools companies since the mid-1980s.

Since 2002, Atlas Copco has launched a rock drilling tool for tunneling jumbo called Magnum SR threads on the market. There are three series of products, Magnum SR28, Magnum SR32, and Magnum SR35.

In 2003, Sandvik also launched a rock drilling tool with Alpha330 thread on the market. The design structure of the Alpha thread is also to increase the volume of the steel part at the root of the thread to improve the fatigue strength and fracture resistance of the drill rod. After Sandvik developed the Alpha threaded drill rod, it used a 45 mm diameter nine-tooth button bit in Australia, Brazil, Canada, Finland, South Korea, and Sweden’s underground mines and tunnels. After a large number of tests, the result is that the service life of the drill rod is increased by 30-80%. At the same time, the service life of the shank adapter and button bit of the hydraulic rock drill is also significantly increased, which reduces the consumption of rock drilling tools in the entire excavation project by 20%.

drill rods

Currently, the design and manufacturing of drill rods for tunnel drill jumbos have a high level of specialization and various high-performance materials in their production. In response to different engineering needs, drill rods of various shapes and specifications have emerged. In addition, advancements in the manufacturing process have been substantial. Employing advanced heat treatment technology and precision processing equipment has significantly improved the drill rods’ strength, toughness, and wear resistance.

Simultaneously, strict quality control measures are implemented during the manufacturing process to ensure the accuracy and consistency of drill pipes. These improvements contribute to the production of high-quality drill rods that can meet the demanding needs of tunnel drill jumbos in various construction scenarios. The combination of specialized design, advanced materials, and improved manufacturing processes underscores the commitment to delivering reliable and efficient tools for tunneling and drilling operations.

Although the drill rods for tunnel drill jumbos have made considerable progress, there are still broad prospects for future development. We have reason to believe that with the continuous advancement of science and technology and the continuous promotion of the spirit of innovation, future drill rods will have higher performance, broader application prospects, and better environmental awareness.

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