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Matters Needing Attention In The Work Of The DTH Bit
Jun 05, 2018

The wear of the bottom spline groove usually occurs in the abrasive layer.

In the formation of high abrasive grains, the wear of DTH bit is usually faster than that of alloy tooth. It is usually called "dive bit erosion".


In order to minimize the cracking of alloy teeth, they should be lapping to 9 mm above the surface of the DTH bit.


If the drill bit is not evenly worn, it may be improper grinding, bending or overpulling the drill rod, which can also cause cracks on the surface of the DTH bit, causing large metal drop.

The depth of the chip should be controlled by grinding and high bit rate to control the wear of the DTH bit. The trench must be continuously grooved to ensure that the cuttings are well cleaned.


Improper Kong Qingjie and excessive wear usually result in re drilling, resulting in deformation around the vent and groove. Therefore, grinding should be carried out to ensure that air can successfully remove debris from drilling holes.


The serious erosion of the DTH bit and the energy generated by the piston hitting the DTH bit will cause the alloy tooth to fall from the DTH bit. It is usually called "meshing". Even if the bit is eroded, it will happen. When drilling soft strata, the DTH bit must be removed regularly and cleaned so that the surface of the DTH bit is often in contact with the bottom rock.


Control and ballistic wear are the most serious wear because they rotate at high speed and are more swaying than the center gear. The wear of ballistic teeth and wear of drill tool steel will cause blockage, pause, penetration rate and alloy tooth failure of DTH Drill.


The new alloy tooth can work under high pressure, but with the wear of the alloy tooth, the appearance of the aircraft will produce horizontal or shear loads at the bottom.

The increase in rotational speed does not increase permeability, but increases wear frequency, especially abrasion.


Under the condition of grinding, it is suggested to control the wear frequency according to the required drilling depth so as to determine the frequency needed for regrinding.


Although different manufacturers, we suggest that the width of flat teeth should not exceed 1/4's bottom diameter.

The flattening of the surface teeth usually indicates that the impactor lacks flow energy or torque.


Check the DTH bit to see if there is a slight hot crack at the bottom, or a similar snake skin crack, or a surface crack caused by the overheating of the alloy tooth. If this situation is not corrected, cracks will cause surface debris and eventually fail at the bottom. Before the occurrence of extreme plane width, snake skin may occur under certain rock conditions, and it can be compensated by grinding the affected area slightly.


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