Core drilling rig accessories
Sinovogroup produces and sells various types of drilling rig matching accessories, which can also be customized according to your needs.
The Selection of the Drilling Parameters
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 equipment and core barrels, drilling depth and the structure of drilling holes, should be considered also.
a. Bits Type: The natural diamond grains 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 accordingly higher.
d. Rock Properties: High rotary speed is suitable for medium hard, complete rock formations; 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 Barrels: 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't use the high rotary speed.
The following are some pictures of core drilling rig accessories：