Drilling Tools core bits for Core Drilling Rig
According to your project requirement, we choose the suitable
drilling tools for you. We can supply complete drilling tools:
drilling rod, lock adapter, hoisting plug, big spannor, fork, mud
pump, reamer, casing, alloy bit, diamond bit and so on.
Core bits
The selection of the Drilling Parameters
A.Influence Factors of Rotary speed
When deciding the specific peripheral velocity of bits,in addition
to bit type and bit diameter.other factors such as rock
properties,diamond sizes,drilling equipments and core
barrels,drilling depth and the structure of drilling holes,should
be considered also.
a.Bits type:
The natural diamond grain on surface set core bit are large and
self-sharpening easily,in order to protect the exposed diamond
grains,the rotary speed of surface set core bit should be lower
than the Impregnated Core Bit.
b.Bit diameter
In order to reach a proper linear velocity,the rotary speed of the
small diameter bit should be higher than the big diameter bit.
c.Peripheral velocity
From the formula of rotating speed,we can find the liner velocity
is proportionate to the rotating speed.It means the higher speed of
the liner velocity,rotating speed is according higher.
d.Rock properties
High rotary speed is suitable for medium hard,complete rock
formation;In broken,fractured,mixed formations with high vibration
when drilling,drillers should slow down the rotary speed according
to the broken level of the rock;in the soft formations with high
drilling efficiency,in order to keep cooling and carry out the
cuttings,the penetration speed needs to be limited,as well as the
rotary speed.
e.Diamond sizes
The larger the diamond size,the quicker the self-sharpening.To
avoid the bit face chipped or cracked,the
rotary speed of the bits with big diamonds should lower than the
bits with small diamonds.
f.Drilling equipments and core barrel
When the drilling machine is with poor stability and the drill rods
have a low intensity,correspondingly,the rotary speed should be
slowed down.If the lubricants or other similarities for decreasing
the vibration are adopted,the rotary speed could be raised.
g.Drilling depth
When the depth of the drilling hole becomes deep,the weight of the
core barrels will be larger;the pressure situation is more
complex;it takes larger power while rotating the core
barrels,Hence,in the deep hole,because of the limit of the power
and intensity of the core barrels, the rotary speed should be
decreased,in shallow hole,conversely.
h.Structure of drilling holes
High rotary speed can be used in the condition that the borehole
structure is simple and the clearance between the drill rods and
borehole wall is small.On the contrary,the drilling hole with a
complex situation,lots of changeable diameters,big space between
the drill rods and borehole wall,it causes poor stability and can
not use the high rotary speed.
