will not produce the impact work required for drilling. Under the condition that
the piston does not exceed the maximum stroke, the bigger the gas supply
pressure selected, the better the drilling performance.
(3) Pressure fluctuation will occur in the intake chamber at low piston speed,
especially at the end of the stroke, which lasts for a long time. This fluctuation
is unavoidable at low speed, but it can be greatly reduced by increasing the flow
area of the chamber. This method is also easy to realize in technology. The
analysis results can be used as a reference for the design theory and drilling
technology development of large diameter pneumatic DTH hammer.
11.5 Design of Large Diameter DTH Hammer Bit
and Spherical Tooth Layout
11.5.1 Rock-Breaking Process by Impact
Reasonable arrangement of spherical teeth can effectively improve drilling efficiency, reduce energy consumption, ensure equal wear of spherical teeth, and
improve bit life. It is of great significance for large diameter DTH hammer drilling.
Through theoretical analysis and LS-DYNA simulation, the rule of rock breaking
by two spherical teeth is obtained, and the reasonable spacing of spherical teeth and
the arrangement scheme of spherical teeth for large diameter DTH bits in specific
rock are obtained.
As an important part of DTH hammer, the drilling bit directly acts with rock and
soil, and its drilling performance and life affect the whole machine. Figure 11.26
shows various drilling bits of pneumatic DTH hammer. The interaction mechanism
between drilling bit and soil and the optimization of drilling bit have always been
the focus of research. Many scholars have studied the rock-breaking mechanism of
single cylindrical teeth (spherical teeth, conical teeth, and warhead teeth) under
impact, but seldom involved the combined impact breaking principle between two
Fig. 11.26 Pneumatic DTH hammer drilling bit. a DTH cylindrical drilling bit produced by Atlas
Copco; b DTH drilling bit produced by Boart Long year; c DTH drilling bit produced by Sandvik;
d DTH drilling bit produced by Ingersoll-Rand
240
11 Pneumatic Down-the-Hole Hammer
the piston does not exceed the maximum stroke, the bigger the gas supply
pressure selected, the better the drilling performance.
(3) Pressure fluctuation will occur in the intake chamber at low piston speed,
especially at the end of the stroke, which lasts for a long time. This fluctuation
is unavoidable at low speed, but it can be greatly reduced by increasing the flow
area of the chamber. This method is also easy to realize in technology. The
analysis results can be used as a reference for the design theory and drilling
technology development of large diameter pneumatic DTH hammer.
11.5 Design of Large Diameter DTH Hammer Bit
and Spherical Tooth Layout
11.5.1 Rock-Breaking Process by Impact
Reasonable arrangement of spherical teeth can effectively improve drilling efficiency, reduce energy consumption, ensure equal wear of spherical teeth, and
improve bit life. It is of great significance for large diameter DTH hammer drilling.
Through theoretical analysis and LS-DYNA simulation, the rule of rock breaking
by two spherical teeth is obtained, and the reasonable spacing of spherical teeth and
the arrangement scheme of spherical teeth for large diameter DTH bits in specific
rock are obtained.
As an important part of DTH hammer, the drilling bit directly acts with rock and
soil, and its drilling performance and life affect the whole machine. Figure 11.26
shows various drilling bits of pneumatic DTH hammer. The interaction mechanism
between drilling bit and soil and the optimization of drilling bit have always been
the focus of research. Many scholars have studied the rock-breaking mechanism of
single cylindrical teeth (spherical teeth, conical teeth, and warhead teeth) under
impact, but seldom involved the combined impact breaking principle between two
Fig. 11.26 Pneumatic DTH hammer drilling bit. a DTH cylindrical drilling bit produced by Atlas
Copco; b DTH drilling bit produced by Boart Long year; c DTH drilling bit produced by Sandvik;
d DTH drilling bit produced by Ingersoll-Rand
240
11 Pneumatic Down-the-Hole Hammer