With the development of the economy, enterprises generally begin to pursue low-cost and high-efficiency construction products so that the market demand for drill rod performance is getting higher and higher, and how to extend the service life of drill rods has become a problem that manufacturers should consider. Hollow steel is the main raw material for producing drill rods, and its quality directly determines the service life of drill rods. Therefore, the use of high-quality hollow steel is one of the important ways to prolong the service life of the drill rod.

Although according to the needs of rock drilling, there are various types of hollow steel, including hexagonal, square octagonal, circular, square, rhombus, and other shapes according to the cross-sectional shape, we can choose according to the use conditions and rock characteristics. But will it affect the service life of the drill rod by producing irregular holes in the rolling?

Hollow steel produces irregular hole shapes, that is, shaped holes usually caused by factors such as uneven heating and poor adjustment of hole shape during the rolling process.

When making a drill rod, it will have the following effects:

1. When making drill rods, the difference in wall thickness is too much, resulting in uneven heating temperature and different plastic deformation of the metal, resulting in uneven end surfaces and different sizes on both sides of the collar plate after reaming and rolling.

2. Due to the irregularity of the hollow steel hole shape, reaming and forging collar plate when the resistance increases, accelerating the reaming needle and collar plate needle wear, reaming needle and collar plate needle easy to fracture. At the same time, the surface of the reaming needle and collar plate needle will be pulled and stretched, resulting in burrs on the inner surface of the core hole after reaming and forging the collar plate.

3. For the hydraulic collar plate machine, the collar plate needle is generally driven by air pressure. When encountering resistance, the collar plate needle will automatically retreat, causing the illusion that the collar plate needle passes through the water hole, thus creating the collar water hole blocking and resulting in the generation of scrap. At the same time, the diameter of the hollow steel core hole is too small. In the process of forging the collar plate, under certain variables, the metal deformation that occurs will also cause the water hole of the collar plate to be blocked.

4. The hollow steel core hole is irregular, resulting in different wall thicknesses of the core hole. When forging the collar plate, if there is uneven force, the collar plate will be formed unevenly, forming sharp corners. At the same time, the force on the mold is not the same size, which will cause the mold deformation and wear degree to be not the same, accelerating the mold scrap.

5. When forging and reaming the collar plate of hollow steel with an irregular core hole, the water hole of the shank and collar plate will produce sharp corners and burrs, forming stress concentration points. Due to the harsh service conditions of the drill rod, the corrosion of mine water will accelerate the corrosion of the thinner side of the hollow steel core hole, and the stress concentration point and mine water corrosion will shorten the service life of the drill rod.

To sum up, an irregular core hole of hollow steel has an influence on the manufacture of drill rods, which will not only cause cost wastage but also shorten the service life of drill rods. Therefore, the quality of the hollow steel core hole is the premise to ensure the quality of the drill rod.