DTH Drill Bits

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 energy 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 air pressure DTH drill bits. It is mainly used in large open-pit mines, underground ore mining, anchoring engineering, quarrying, construction engineering rock drilling, and large-scale engineering construction.

Working principle of DTH drill bit

When the DTH drill bit is working, the pressure regulating mechanism is advanced to push the drill tool continuously forward 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. 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, thus forming a blast hole.

The structure of DTH drill bit

The DTH drill bit consists of carbide inserts, exhaust holes, head, splines, and impact end faces.

• Carbides: Cemented carbides mainly bear the high-frequency stress wave from the hammer, and directly transmit the high-frequency stress wave to the rock surface and cut it.
• Exhaust holes: The wear of DTH drill bits and carbides during drilling is related to the material properties of the skirt body and carbides and the size and flow velocity of cuttings at the bottom of the hole.
• Head: The crown shape of DTH drill bits includes two airfoil, three airfoil, and four airfoil. The selection of the crown shape of the DTH drill bit is closely related to the field working conditions, the depth, and the diameter of the hole.
• Spline: The DTH drill bit both impacts and rotates to break rock. Additionally, the drill pipe provides a torsional moment through the spline set at the end of the drill bit.
• Impact end face: The arrangement of the carbides of the DTH drill bit mainly depends on the shape of the end face, which directly affects the energy transfer efficiency and strength of the DTH drill bit.

Features:

• Using high-quality materials and a heat treatment process, it has excellent hardness and wear resistance with guaranteed quality, which makes the drilling work efficient and fast.
• Three drill bit end face designs: concave, flat, and convex, which can adapt to various complex geological environments.
• Strict quality control and testing ensure the stability and reliability of the drill bits in use.

The DTH drill bits are divided into the following three types according to the shape.

• Flat type: Flat face drill bits have buttons arranged on the end face perpendicular to the center line of the drill bit, and the gauge button is installed on the beveled surface with a certain inclination angle, which can effectively scrape the rock. It has features of a simple structure, is easy to process, has a high drilling speed, and is suitable for drilling very hard rock formations and corrosive rock formations at high air pressure.
• Convex type: Convex drill bits are a convex shape in the middle, which aims to reduce the stress of the gauge button and facilitate the centering of the drilling holes. The end face of the drill head is rounded and has the characteristics of self-sharpening, high speed, and smooth drilling speed, but it is more difficult to process than the flat drill bit, and the buttons wear faster and are suitable for drilling soft and medium hard rocks with low and medium air pressure and fast drilling speed.
• Concave type: Concave drill bits are a concave shape in the middle, which can produce a central rock pillar with a centering effect during drilling, effectively pre-exhaust holding the drilling from tilting, and the drill bit body bihas high strength. It is suitable for all rock formations, especially good in medium-hard rock, with good drilling straightness and good slag removal.

1. What is the composition of the DTH drill bit?

The DTH drill bit consists of carbide inserts, exhaust holes, head, splines, and impact end faces.

2. What are the shapes of drill edge of DTH drill bit?

According to the shape of the drill edge, DTH drill bits include blade type, button type, and mixed type.

Blade drill bits have carbide inserts embedded in the head of the drill bit.

Button bits have drilling holes in the head of the drill bit. Usually, the carbides are embedded into the drill body by brazing, hot embedding, and cold pressing.

Mixed drill bit: The periphery of the mixed drill bit is inlaid with blades, and the center depression is inlaid with button inserts.

3. What are the crown shapes of DTH drill bits?

The crown shape of DTH drill bits includes two airfoil, three airfoil, and four airfoil. The selection of the crown shape of the DTH drill bit is closely related to the field working conditions, the depth of the single hole, and the diameter of the hole.

4. What are the end face shape of DTH drill bits?

The arrangement of the carbides of the DTH drill bit mainly depends on the shape of the end face, which directly affects the energy transfer efficiency and strength of the DTH drill bit. The end face shape of the DTH bit contains four types: flat face, convex face, tower type face, and concave face.