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.
