DIAMOND BIT

 Diamond bit can be divided into 2 main categires.

 Surface bits are manufactured with the usage of Bortx, where the particle size is 10~80pcs are used perarat.  Various types are manufactured according to grade. Impregnated bit is  manufactured with the combinationo of synthetic diamond powder and metal powder through sintering.

30~50 mesh particle sizes used. Metal powder is combined with diamond powder to increase hardness of the martix. Tungsten, Cobalt, Nickel, Bronze powder are used for metal  poweder.

Hard matrix is used for soft-rock and soft martrix is used for hard-rock layer.

DIAMOND BIT SELECTION

The martrix hardness is the most important element  when selecting the appropirate diamond bit. Generally, hard matrix for soft-rock, medium matrix for medium hard-rock and soft matrix for hard-rock are selected.

However, extreme fragmentation layers in soft-rock layers can cause damage to the daimond bit during drilling with soft martrix, so the above must not be used as a general guidline. Therefore, the initial bit should use a soft matrix and gradually be exchanged according to bit wearing rate. This process should be used to reach the perfect bit selection.

The general standard for bit selection is as follow,

1. For soft-rock layer, usage of large diamond particle size and hared matrix.

2. Fro medium hard-rock layer, usage of medium diamond particle size and medium or soft martix.

3. For hard-rock layers, usage of impregaetaed diamond and soft martix.

DIAMOND BIT USAGE GUIDANCE

1. Usage of drilling fluid must never be discontinuded druing boring. If drillingfluid is discontinued, the bit will " burn up" or decrease the life span dramatically. This can result in accidents.

 

2. From the beginning to ending stage of boring, sufficient amount of driling fluid must used be and sludge must be removed sufficiently from the bottom section of the hole. If sludge piles up in the bottom section of the hole, drilling speed will decrease, casue bit breakage and result accidents.

 

3. If the diameter of the hole reduces during boring, reaming a new bit is not recommended. A new bit should be installed after rotating and passing through the accuragte sized reaming shell.

 

4. After usage of the metal bit, metal fragments must be completely removed for the hole before diamond bit usage.

METAL CROWN BIT

Metal bits are manufactured with tungsten carbide, replacing diamonds, and have a lower cutting rate than diamond bits in hard-rock layter. Additionally, core recovery is low. Customized sizes are available with 5*5*8, 6*6*9, 8*8*10 size being mainly manufactured. For soft-rock layers, tungsten carbide is manufactured with a high hardness rate and low deflective strength. For hard-rock layer, tungsten carbide is manfactured with a low hardness rate and higher deflective strength.

Core barrels are used to reatin rock core samples during the driling process. Core barrels are manufactured in a variety of sizes and designes according to usage

CORE BARREL

SINGLE TUBE CORE BARREL

Single tube core barrels are generally suitable for coring in evenly distributed stone layers. Single tube core barrels are not suitable for easily eroding layers like unstable soil layers or water circulating layers. Core recovery is lowest in single tube core barrel.

Double tube core barrels consist of an inner tube and an outer tube. Due to the fact that drilling  fluid flows between the tubes, recovered core does not contact with drilling fluid.

DOUBLE TUBE CORE BARREL

TRIPLE TUBE CORE BARREL

Triple tube core  barrels have a core case tube manufactured within the inner tube. Generally, the core case tube is divided vertically, core recovery is highest in triple tube core barrel.

CORE BARREL(DOUBLE TUBE)

CASING PIPE

Caing pipes are tubes most commonly used in directional boring, to maintain a hollow wall of desired depth. Casing pipes are generally used for unstable soil layers and are recoverd.

DRILL ROD

Drill rods are connected to core barrels and undergoes the function to convey rotation and pressure to the bit during directional boring. Drill rods also pass on drilling fluid to the bit.