Rock drilling tools are crucial for mining, energy construction, foundation engineering, traffic road development, and other construction fields. Because it is a tool product matched with rock drilling machinery, there are varieties and specifications, and the methods of use are also different. According to the types of rock drills used in geotechnical drilling and excavation engineering, the supporting rock drills include top hammer rock drilling tools, DTH drilling tools, mining core drilling tools, reverse patio drilling tools, mechanical cutting drilling tools, and geological exploration drilling tools. In the previous article, we introduced the relevant content of the top hammer rock drilling tools, but the DTH drilling tools are also widely used. It is mainly composed of DTH drill bits, DTH drill pipes, and DTH hammers. Today we are sharing with you the DTH drill bit.

What is the DTH drill bit?

The DTH drill bit is a kind of drill tool connecting the impactor with the spline of the drill bit to guide and transmit the rotation for the impact, with the drill bit and the DTH hammer diving into the hole to break the rock. DTH drill bits include high, medium, and low wind pressure DTH drill bits. It is mainly used in large open-pit mines, underground ore mining, anchoring engineering, quarrying rock drilling, construction engineering rock drilling, and large-scale engineering construction.

Next, let’s take a look at the working principle of the DTH drill bit, and the shape and purpose of the drill bit alloy.

Working principle of the DTH drill bit

When the DTH drill bit is working, the pressure regulating mechanism is advanced to push the drill tool continuously and keep the drill bit in contact with the rock at the bottom of the hole. The rotary mechanism makes the drilling tool rotate continuously. At the same time, under the action of air pressure, the impactor piston installed at the front end of the drill pipe continuously impacts the drill bit, and the drill bit obtains energy after the impact, dives into the bottom of the hole, and generates an impact force that squeezes the rock. The rock drilling tools rotation avoids the drill bit hitting the same drilling trace repeatedly and generates a shear force scraping the rock at the bottom of the hole. Under the action of the impact force of the impactor piston and the shear force of the rotary mechanism, the rocks are constantly being crushed and sheared away. The air pressure enters through the gas joint, reaches the bottom of the hole through the hollow drill pipe, and blows the cut slag from the annular space between the drill pipe and the hole wall to the outside of the hole, thus forming a blast hole.

Alloy shape and application of DTH drill bit

Most DTH drill bits use spherical rock-drilling carbide button heads and spline-shaped shank adapters. DTH drill bit carbide button includes hemisphere button, parabolic button, ogive button, and other types according to the shape. Hemispherical buttons have a strong bearing capacity and good wear resistance, suitable for drilling hard, medium-hard, and abrasive rocks. The ogive button and parabolic button have fast drilling speeds and are suitable for drilling medium-hard and non-abrasive rocks.

Because of the tough working environment of the DTH drill bit, what are its material selection requirements?

Selection of DTH drill bit material

1. The DTH drill bit material is selected with a higher surface hardness to enhance wear resistance, and better core toughness to enhance the impact resistance. To avoid brittle rupture and fatigue break, the material should have good fracture toughness, fatigue strength, and fracture strength.

2. It has high hardenability. It is beneficial to improve the surface yield strength and the fastening force of the hole to the carbide button. It also improves the yield strength and toughness of the core.

3. It can resist corrosion when encountering gas and liquid in the underground rock formation.

4. Under a high temperature, the hardness of the material is stable and not easy to soften.

5. Good process performance, such as good forge ability, etc.

6. High metallurgical quality, good organizational uniformity, fewer impurities, especially low phosphorus content, and uniform carbide.

In conclusion, the selection of DTH drill bit material should have high dynamic load strength and excellent wear resistance. The structure should be conducive to pressure air into the bottom of the hole to cool the drill bit and remove rock slag. The shape is simple and easy to manufacture. The ratio of drill bit weight to piston weight should be close to 1 to improve the efficiency of impact energy transfer.

Of course, high-quality drill bit materials are not enough to achieve optimal performance and prolong drill bit service life. If you want to get the best results, the premise is to choose the right DTH drill bit. Because DTH drill bits are usually used in conjunction with DTH hammers to drill rock, companies can choose DTH drill bits based on rock conditions (hardness, abrasion) and drill type (high wind pressure, low wind pressure). Different carbide button and button distribution methods are suitable for drilling different rocks. In short, the drilling speed and the service life of the drill bit can be improved when all aspects of the drill bit are in line with the operating conditions.