Rock drilling tools are essential products in the fields of mining, energy construction, foundation engineering construction, traffic road development, and other construction projects. With the rapid development of the economy, people have higher requirements on the performance and life of drilling tools. The drill rod is one of the main products of drill tools. In practical use, it is easy to consume a large number of wearing parts because of its harsh stress conditions.  Therefore, it is necessary to improve the service life of the drill rod.

To know how to improve the service life of the drill rod, we first need to know what factors affect it and solve the problem fundamentally. There are many factors affecting the service life of the drill rod. I have shared relevant content before, so I won’t repeat here. Let’s focus on the fracture of the drill rod, because it is the most prominent factor that affects the service life of the drill rod. Mainly in the following points:

1. Fatigue damage

Fatigue damage generally begins at cracks, defects, or the lowest hardness. Although these cracks or other defects are too small to be observed with the naked eye, they suddenly break along the fatigue section under the long-term action of cyclic repeated loads until the remaining section is insufficient to support the load.

2. Forging and heat treatment defects

When the drill bit and shank adapter are forged and heat treated, a transition zone is formed between the heated part and the unheated drill rod. This zone is the lowest hardness and strength, so it is also the easiest to break.

3. The problem of rock drill steel

The rock drill steel is cast into ingots from the steel furnace, then formed in the rolling mill, which may produce more or fewer defects, and even produce a decarburized layer with lower hardness. Another indicator of the quality of rock drill steel is its heat treatment state. After being formed, the rock drill steel grain is coarser, organization disorder, and there is high residual stress. Therefore, making it into a drill rod will inevitably affect its strength and life.

According to the above three reasons, we can prevent the short life of the drill rod caused by the breakage of the drill rod in advance.

If we want to maximize the service life of the drill rod, we must adapt the drill rod to the properties of the drill bit, the rock drill, and the rock.

1. Select the rock drill and drill rod according to the type of rock

To ensure long enough service life when drilling hard rock, the drill rod must be made of alloy hollow steel with high fatigue strength. The type of rock drill also has an important influence on the service life of the drill rod. A light rock drill with a high impact frequency should be used to drill hard rock. Rock drill with low frequency and high impact power should be used for rock drilling with high wear resistance. In addition, it is also necessary to avoid the use of a small section drill rod that is unfit for the type of drill, to avoid excessive bending and early fracture of the drill rod.

2. Select the drill rod with the appropriate length according to the blast hole depth

When drilling deep blast holes, avoid using the same long drill rod from opening to end. Because, when a long drill rod is used to open the hole, the unsupported part of the drill rod is long, easy to bend, and bending stress is also larger.

3. Select the appropriate drill bit and pay attention to the wear degree of the drill bit

Do not select the drill bits with a large section that is not suitable for the drill rod. Otherwise, the drill rod will be overstressed and easily broken early.

4. The worn rock drill sleeves must be replaced in time

When using the worn drill sleeve, the gap between the shank adapter and the drill sleeve increases, and the shank adapter is skewed, making the impact of the piston an inclined impact, resulting in an eccentric load, causing additional stress, which does not only reduce the drilling speed but also reduces the drill rod service life.

5. To maintain proper thrust

When the rock is hard, the drilling speed is slow and the thrust is often insufficient. When the thrust is too large, it will cause large bending stress. Therefore, too large or too small thrusts can accelerate the fatigue failure process of the drill rod.

6. Precautions for using air leg rock drill

It is necessary to prevent the axis of the rock drill and the drill rod from being inconsistent due to improper operation, causing eccentricity, resulting in increased bending stress on the drill rod and accelerated drill rod fatigue; After opening the hole, let the rock drill hang on the drill rod for a while, to aovid the drill rod to bend.

7. Avoid scratches and rust on the surface of the drill rod, resulting in early fracture of the drill rod.

In the process of use, whether it is replacing the drill bit or when the drill is stuck, it is necessary to avoid the trauma caused by hitting the drill rod;

To avoid corrosion on the surface of the drill rod and the inner wall, the drill rod should be placed in a relatively dry room;

The drill rod that is not used immediately should be avoided in the well;

The inner and outer surfaces of the wet drill rod should be blown to dry completely after use.

8. Straighten the bent drill rod in time

Hammering should be avoided when correcting, and a hydraulic straightening machine can be used.

Improving the service life of the drill rod can not only improve the operation efficiency but also improve the economic benefits of the enterprise. So it is very important for both the supply side and the demand side. At the same time, in addition to the content shared above, the operation procedures must be strictly implemented and the technical level must be continuously improved. Only continuous prevention and improvement can the service life of the drill rod reach the best.