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 to have 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 connections. To lubricate and reduce wear, cooling, cleaning, rust and corrosion
prevention, shock absorption, stress dispersion buffer, and so on, to reduce
ablation and wear, and 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 drill, 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.
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