Rock Drill Bits

Drill bit is composed of two parts: a skirt body and a carbide button. The skirt body and the rock drill rod are connected by threads and driven by the rock drill, and the carbide button drills and breaks the rock. Therefore, the rock drill bit is the part that suffers the most shock and wears in the entire system. The basic principles of geometric structure and parameter design of rock drill bits are effective rock breaking, timely powder discharge, stable shape, strong wear resistance, round and straight drilling, flexible rotation, reliable connection, convenient disassembly, easy manufacture, and beautiful appearance. The best geometric structure and parameters of rock drill bit form the basis of the main technical and economic indicators such as drilling life, drilling speed, carbide utilization rate, cost, and market competition.

Diameter of rock drill bit:

• chisel bits: 32mm-42mm
• cross bits: 34mm-65mm
• X bits: 55mm-65mm
• button bits: 38mm-150mm

Classified by connection method:

There are mainly taper bits and threaded bits.

The tapered bit is a rock drilling tool that works with the taper of the rod through the taper of the skirt of the drill bit. It is mainly used in mining, tunneling, roadway boring, stone mining, and other working conditions.

Tapered taper: 7°, 12°

The threaded bit is reliable, can transmit a large torque, and is convenient for extending the drill rod. It is mostly used on a drilling frame or a drill truck for rock drilling to drill deeper holes with larger diameters.

Threaded bits are classified according to thread form:

There are mainly two types of R-thread and T-thread.

R-thread specifications are R25, R28, R32, R38, etc. The basic dimensions and button profile of the R-thread mainly refer to the industry standard ISO10208.

T-threads specifications are T38, T45, T51, etc. The basic dimensions and button profile of T-threads mainly refer to the corporate standards of each company, but the dimensions and button profile of each company are almost the same. Therefore, the drill bits have high interchangeability in the industry.

Application: When using a hand-held or leg-type light rock drill and a small-diameter drill bit for shallow hole drilling, it is mostly equipped with tapered drilling tools. When the diameter of the drill bit is large, and the drill frame and rock drilling rig are used underground or in the open for medium and deep rock drilling, threaded drilling tools are used.

Classification by shape and structure:

There are mainly chisel, cross, X shape, button, and other types.

The button shape is the most commonly used structure for threaded bits, so it is divided into an ordinary flat face, retrac flat face, reaming semi-dome, reaming guide, ordinary drop center, and retrac drop center, etc.

Application:

• Chisel bit is suitable for light rock drills to drill rock formations with low hardness and is easy to sharpen.
• Cross-type and X-type drill bits are suitable for drilling cracked rock formations and highly abrasive rock formations under the conditions of rock drills with larger impact power and strong radial abrasion resistance.
• Under the condition of a larger impact power rock drill, the button bit has better applicability than the sheet-shaped insert drill bit and has higher rock drilling speed and service life, and the drilled holes are rounder. The inner water hole should deliver mineral water with a pressure of 0.4MPa to ensure dust removal and discharge of rock powder: the outer surface of the rock drilling tool will also be strongly abrasive with the rock surface.

Comparison of rock drill bits by head shape

Bit face	Application	Rock consolidation	Drilling speed
	For use in all rock conditions, especially for harsh or abrasive conditions such as granite, basalt, and hard limestone	much	slow
	Drill straighter holes in less consolidated rock	middle	middle
	For soft rock, such as low-silica shale and limestone	less	fast

Carbide button classification

Carbide button	Product	Advantages	Application
Conical Button		High drilling efficiency	medium-hard rock such as limestone, gravel, marble, pyrite, etc. from f8 to f14.
Parabolic Button		The button feeding speed is fast, which can not only ensure a certain rock drilling efficiency but also have a better service life.	medium hard rock moderately corrosive rock formations
Ogive Button		Fast button feed speed and excellent rock drilling efficiency	soft rock such as shale, clay rock, sandstone, and rock salt below f8