With the development of the economy and the advancement of science and technology, the number of hydraulic rock drilling rigs on the market is increasing, the drilling rigs have more and more models, and the specifications of the supporting drill rods are also more and more. In the drilling, the drill rod will appear various forms of failure after continuous drilling. It includes internal and external thread wear, external thread fracture, internal thread longitudinal cracking, and rod fracture. These different forms of failure reduce the production efficiency of rock drilling operations, increase production costs and make it difficult to exert the high-efficiency characteristics of hydraulic drilling rigs. Therefore, how to prevent the failure of the drill rod is particularly important.

1. Use lubricating oil

In the drilling, use lubricating oil for internal and external thread connection. In order to lubricate and reduce wear, cooling, cleaning, rust and corrosion prevention, shock absorption, stress dispersion buffer, and so on, to reduce ablation and wear, avoid premature failure of the internal and external thread. At the same time, the operator should take care of the drill rod to avoid surface mechanical damage. Once caused surface trauma, it is fatal to the high-strength Cr-Ni-Mo steel carburized workpiece.

2. Strengthen the surface treatment of the billet

In surface quality control, strengthen the billet grinding skin treatment. Clean up the surface defects of the billet as much as possible to ensure the surface quality of the hollow steel without new overheating defects.

3. Take effective safeguard measures in heat treatment and machining

In terms of heat treatment quality, the following substances are controlled: martensite, residual austenite, and network carbide, and the hardness of the surface infiltration layer to the matrix is reasonably distributed.

The machining quality should control the tolerance of internal and external threads to avoid difficulty in loading and unloading, and the surface roughness should meet the requirements to avoid serious tool marks.

4. Eliminate quality problems

The forging quality of the inner thread of the drill rod is the factor that causes the failure of the internal thread. Therefore, quality problems such as forging cracks, overheating, overburning, and folding cannot occur.

5. Eliminate operational problems

During the use of the drill rod, with the gradual wear of the internal and external threads, the matching gap of the internal and external threads gradually increases. Under the influence of tension and compression stress, the internal and external thread “string movement” occurs, and the friction heat generation on the contact surface increases, which will cause the instantaneous force at the contact point of the internal and external thread to be too large. At the same time, when it is difficult to unload the drill rod, the drilling rig operator usually starts the rock drill to drilling, which will loosen the connection between the internal and external threads, which will cause damage to the drill rod.

To sum up, production quality and operation standards are the keys to determining the service life of the drill rod. Therefore, in the production process of the drill rod, it is necessary to strictly control the quality of the smelting, rolling, machining, and heat treatment of the raw material of the drill rod and to standardize the use of the operator. Only when the drill rod has good production quality, the performance of the drill rod be better exerted, thereby obtaining a high service life.