The industry that produces pig iron, steel, industrial pure iron, and ferroalloy is called steel industry. It is not only one of basic industries of all industrialized countries in the world, but also an important indicator used by economists to measure the economic strength of various countries. Rapid development of iron and steel industry in recent years not only demonstrates the importance people attach to basic industries but also shows the demand for iron ore.  Further exploration and exploitation of iron ore resources are inseparable from hydraulic mining rock drilling jumbos.

What is a hydraulic mining rock drill jumbo?

Hydraulic mining rock drill jumbo is a new type of mining rock drilling equipment. Compared with traditional pneumatic rock drill jumbo, high-power hydraulic rock drill jumbo, it has characteristics of large output energy, high efficiency, low energy consumption, and good reliability. Rock drilling tools generally used in this type of rock drilling equipment are mainly shank adapters, MF rods, and button bits. MF rod is a drill rod with external thread at one end and internal thread at the other end. It is mainly a supporting tool for hydraulic mining rock drill jumbos, and its consumption accounts for 70-75% of consumption of hydraulic mining rock drill jumbos drilling accessories.

Service conditions of drill rods for hydraulic mining rock drill jumbos

When drilling, internal thread of MF rod is connected to the shank adapter, and external thread is connected with internal threads of several MF rods to form a rock drilling tool set, and terminal is connected to a threaded button bit. Threaded button bit usually drilling hole depth between 25~30m. In drilling, impact energy and rotational torque output by hydraulic rock drill are effectively transmitted along drill rod, and finally, impact energy and rotational energy are transferred to the rock by rock drill bit so that rock is effectively broken. It is necessary to bear tensile stress, impact vibration, bending stress, and torque stress caused by rotation of rod in rock for a rod to have severe friction or collision with the rock wall in drilling. In addition, in rock drilling, a high-pressure water medium needs to be circulated in middle hole of drill rod to effectively discharge rock powder produced by drilling and cool rock drilling tools. Most of this water is extracted on-site from the water source in the mine, and its pH is high, which also has a strong corrosive effect on inner hole wall of drill rod. Therefore, mining MF rods work under high impact energy, multiple cycles of complex alternating stress and corrosion fatigue loads, and their service conditions are very harsh.

Factors affecting service life of drill rods for hydraulic mining rock drill jumbos

There are many factors affecting service life of drill rods for hydraulic mining rock drill jumbos. In addition to the quality control of steel smelting and rolling, machining and heat treatment quality control of the drill rod by the manufacturer during the production process of the drill rod, such as difference in hardness of drilling rock layer, and whether drilling jumbo operator controls parameters such as propulsion force, impact energy of rock drill, a torque of drill, and pressure of flushing water, it will have a major influence on service life of drill rod.

In addition, in rock drilling, with the deepening of drilling hole, drill rod of hydraulic mining rock drill jumbo also needs to be constantly lengthened. In the process of loading and unloading drill rods, it is important to observe the degree of wear of drill rod threads and replace them in a timely manner.  As the internal and external threads of drill rod wear to varying degrees, thread fit gap will become larger and larger. The wear will also change from initial micro-movement wear when the fit is good to impact wear when the fit gap is large. Impact wear will cause threads to wear rapidly, resulting in early wear and tear of drill rod.

Drill rod of hydraulic mining rock drill jumbo is an important part of rock drilling tools of mining rock drill jumbo. Drill rod manufacturers can further explore improvement and innovation of production technology and process by understanding various aspects of drill rod production process and mine rock drilling test, to achieve stability and improve product quality and prolong service life of drill rods.