Two Reasons for Failure of Impact Hammer of Friction Welding Drill Pipe

Classification:

Company News

Release time:

2019-08-20

【Summary Description】 Two Reasons for Failure of Impact Hammer of Friction Welding Drill Pipe

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Friction welding drill pipeAccording to the air distribution mode, the impact hammer can be divided into valve type impactor and valve-less impactor. In addition to the different gas distribution methods, its structure is also slightly different, but its working principle is basically similar, except that the valve type impactor has worse anti-pollution ability.

Friction welding drill pipeThere are many reasons for the failure of the impact hammer, but the main form of the impact hammer is not impact, impact weakness and intermittent impact.

Section1 reason: processing defects

The piston and cylinder liner of the impact hammer are closely matched, and the matching length is longer, and the machining accuracy and surface smoothness are required to be higher, which requires very high cylindricity of the piston and cylinder liner. If the cylindricity is not guaranteed, the piston will appear directional or intermittent jamming, and eventually may have to lift and unload the drill pipe frequently for maintenance of the impactor.

In addition, the rigidity of the outer sleeve of the impact hammer is also an important factor restricting the service life of the impactor. If its rigidity is poor, the impact hammer will be deformed due to frequent collision with the well wall during drilling. When the impact hammer is not working, it is often necessary to vibrate, disassemble and clean the impactor, which will aggravate the deformation of the outer casing of the impact hammer. The deformation of the outer casing will cause the internal parts of the impactor to jam and cannot be disassembled, which will eventually directly cause the impact hammer to be scrapped.

SectionTwo reasons:Friction welding drill pipeImpact hammer tail backstop seal is not reliable

At present, the tail of the impact hammer is equipped with a check valve, its structure is shown in the figure. The sealing form is mainly by spherical rubber cap or installed in the metal conical cap on the O-ring compression deformation to backstop sealing. Its backstop function is achieved by the elastomer, and the elastomer generally has a guide device.

This sealing method has the following problems:

(1) There is friction between the spring and the guide device, which will affect the cut-off speed of the check valve;

(2) frequent compression and friction of rubber sealing materials for a long time will cause excessive wear;

(3) spring fatigue damage, resulting in backstop seal failure;

(4) When the gas is stopped,Friction welding drill pipeThe sudden decrease of the internal pressure of the impact hammer will cause the rock powder or liquid-solid mixture to pour back into the inner cavity of the impact hammer, which will cause the piston to jam;

(5) What is more serious is that the water carries rock cuttings into the valve position (valve type impactor), which makes the valve plate unable to normally close the gas distribution, causing the impactor to only discharge cuttings without impact work.

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Key words:

weilida drill