Specific Application and Performance Requirements of Tricone Bits

1. The specific application of the tricone bit

The tricone bit is a metal-sealed rolling bearing, which can stably drill at medium-low WOB and medium-high rotational speed, and is an ideal choice for the upper well section. A variety of high-speed alloy teeth such as offset top spoon-shaped teeth, spoon-shaped teeth, wedge-shaped teeth and bevel-ball teeth can be selected for the insert bit.

The steel tooth drill increases the thickness of the weld layer and the exposed height of the tooth. The bit is equipped with a variety of optional features to improve the ability to adapt to different drilling techniques and various complex formations. The tricone bit can withstand high WOB under normal rotation speed, and can adapt to extremely soft or extremely hard formations with different cutting structures.

The insert drill adopts high-strength and high-toughness alloy teeth, which gives full play to the high wear resistance and excellent cutting ability of the insert drill. The tooth surface of the steel tooth drill is coated with new wear-resistant materials, which prolongs the service life of the drill.

The top of the tricone bit cone adopts diamond composite teeth to enhance the wear resistance of the teeth and improve the service life of the drill bit. The new hydraulic structure improves the cleaning ability of the hydraulic system to the rollers and the bottom of the well, and optimizes the bottom of the well.

The diameter-gauge teeth of the drill body are selected with large-diameter active-cut diameter-gauge ball teeth, so that the drill has a good diameter-gauge function and reverse reaming function. The bit is suitable for small hole drilling operations such as window sidetracking in old wells and deepening in old wells.

Aluminum alloys are mainly cast aluminum alloys. When the rock bit is drilling, it is easy to generate built-up edge, and the roughness of the drilling is poor. When drilling deep holes, it is difficult to remove chips, which may cause the hole wall to bruise, and the chips are blocked in the drill bit. in the groove, causing the drill bit to break.

Aluminum alloy has a small elastic coefficient and a large linear expansion coefficient, so hole shrinkage occurs in drilling. Cast aluminum contains silicon, and the silicon compound is very hard, which will increase the wear of the drill bit. However, aluminum alloy has low strength and low hardness, and the cutting load is small. In addition to pure aluminum, the general aluminum alloy has small plasticity and low elongation, so the chip breaking of the tricone bit is relatively smooth.

Brass-drilled parts are usually cast brass, which is characterized by wear resistance and corrosion resistance, but with lower hardness and strength, less cutting load, and poor plasticity, and chips are broken into pieces.

In the process of drilling brass, the phenomenon of "knife sticking" often occurs, that is, the automatic cutting phenomenon of the rock bit, especially when the hole is about to be drilled, it will automatically fall down, which is very unstable, causing scratches and burrs at the exit of the hole. Or make the drill bit chipped, or the drill bit will break.

2. Performance requirements of tricone bits

To reduce the problem of "knife sticking", the cutting edge should be less sharp, so the rake angle τ=6°~8° at the outer edge of the cutting edge should be reduced. If drilling and pressing a brass workpiece, then τ=10°. Grind the chisel edge to make it narrower, but symmetrical, so that a better hole can be drilled.

Compared with the general mechanical sliding bearing, the tricone bit sliding bearing system is special in bearing structure, load bearing, bearing working environment and relative rotational speed between sliding pairs.

The radial circular runout of the drill tip should be within 0.02mm after the tool of the tri-cone drill bit is clamped. For the machining method of workpiece rotation, the deviation between the workpiece rotation center and the tool center line should be within 0.02mm.

The tool holder overhang should be as short as possible to enhance its mounting rigidity. The cutting fluid should be selected reasonably to effectively reduce the friction in drilling and improve the heat dissipation conditions.

Drilling is generally used for roughing, and the main function of the cutting fluid is to improve the life of the tricone bit, that is, the cooling performance is better. Usually, an emulsified oil solution is used, which has a large heat capacity, high thermal conductivity and good cooling performance.