RU2624274C2 - Processing method of titanium alloys drill pipes threaded joint - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: processing method includes the laser irradiation of the threaded part of the drill pipes, then provide the wear-in of the threaded pipe sections through its circular screwing together - unscrewing. The tightening torque at screwing is set within 90-110% from the pipes maximum operational load, and the number of cycles is set within 5-10.

EFFECT: using of the invention helps to reduce the friction and adhesion properties of the drill tools threaded joints.

1 cl

Description

The invention relates to a technology for processing structural materials, in particular to surface hardening of the threaded part of a drilling tool made of a titanium alloy as part of a submersible drilling complex.

The invention is aimed at reducing the frictional and adhesive properties of threaded joints of a drilling tool and can be used in various branches of mechanical engineering, where it is required to reduce the frictional and adhesive properties of friction pairs of products made of titanium.

To reduce the frictional and adhesive properties of titanium alloys, thermal oxidation is used (B. B. Chechulin, S. S. Ushkov and others. Titanium alloys in mechanical engineering. - L .: Mechanical engineering, 1977), providing the formation of a surface layer with high hardness and wear resistance.

The disadvantage of thermal oxidation is the shallow depth of the hardened layer. In addition, thermal oxidation involves a long exposure at high temperature, which reduces the mechanical properties of the alloys.

A known method of laser processing of products from titanium alloys (copyright certificate No. 1490978, IPC C21D 1/09, B23K 26/00, "METHOD FOR LASER PROCESSING PRODUCTS FROM TITANIUM ALLOYS", Application: 4261166/02 of 06/11/1987), including laser irradiation of the part placed under a coolant layer, characterized in that, in order to increase surface hardness, processing in the mode of surface reflow is carried out in a supersaturated aqueous solution of boric acid with a liquid layer height above the treated surface of 2-13 mm.

The disadvantages of this method are:

- the use of coolant - an aqueous solution of boric acid and, as a result, the use of special containers to ensure the processing process;

- the dependence of the geometric dimensions of the processed products from the geometric dimensions of the tank.

The closest in purpose and technical nature to the claimed object is a technical solution for copyright certificate No. 1490978. This technical solution is selected as a prototype.

The objective of the proposed technical solution is the implementation of a method for processing threaded joints of drill pipes made of titanium alloys, namely:

1) decrease in the moment of unscrewing;

2) the stability of the drill pipe;

3) verification of the design of the threaded connection before operating in automatic mode.

The technical result of this invention is that after laser surface hardening of the threaded part of drill pipes made of titanium and the subsequent cyclic running-in of the threaded joint, which consists in the operation of screwing-unscrewing the threaded joint, the friction and adhesion properties (setting) are significantly reduced in the places of contact threaded joints of drill pipes, and the moment of unscrewing is approximately equal to the moment of make-up.

The technical result is achieved by the fact that the end of the drill pipe with an external thread is subjected to laser treatment with subsequent cyclic running-in of the threaded joint, which consists in screwing-unscrewing the threaded joint, while the tightening torque is 90-110% of the maximum operating load, and the number of cycles is 5 -10.

Drill pipes are made of structural steel as standard and, under normal use, the threaded parts are lubricated with special grease, and there is no problem with loosening. When using titanium alloys as a material for the manufacture of drill pipes, difficulties arose with the "grasping" of the threaded parts. To eliminate the "setting" effect, the contacting threaded surfaces of the end of the drill pipe with external threads are laser-treated. To achieve a technical result, it is sufficient to laser only one end of a drill pipe with an external thread.

After processing, drill pipes are assembled by thread, and a screwing operation is performed. The make-up operation is controlled by an M40-200 torque sensor and amounts to 90-110% of the maximum operating load of 200 Nm. Then, an unscrewing operation is performed.

If the tightening torque is less than 90% of the maximum operating load, the number of cycles increases, if the tightening torque is greater than 110% of the maximum operational load, then there is the possibility of "setting" the threaded connection.

To break in the contacting surfaces of the thread, drill pipes are screwed and unscrewed, the number of cycles is 5-10 times. The essence of the break-in is to eliminate the microroughness of the contacting surfaces of the thread.

It has been experimentally established that a decrease and stabilization of the unscrewing moment occurs after 10-15 cycles.

The invention is industrially applicable in any field of engineering. An example of the application of the proposed method is the use of drill pipes with laser hardening as part of a submersible drilling complex.

A submersible drilling complex made of titanium is a complex set of components and mechanisms and is remotely controlled from a carrier boat. At the base, a drilling complex loaded with drill pipes loaded with laser hardening, stored in a loose state in special storage and transportation containers, is loaded into the carrier boat. The carrier boat leaves the place of basing and goes to the place of drilling. At the same time, drill pipes are in seawater. At the drilling site, the drilling complex is unloaded and installed on sea soil. A drill pipe is taken from the storage and transportation container and screwed onto the rotator of the drilling complex, with a tightening torque of 200 Nm. The drilling process begins. After the drill pipe has deepened to its full length, the drilling process stops and the pipe is unscrewed from the rotator. The next drill pipe is taken, screwed with the first drill pipe by a rotator with a tightening torque of 200 Nm and the drilling process is resumed. The drilling operation continues until the core is taken. Then the drill pipes are unscrewed in the reverse order and are removed into the container for storage and transportation of drill pipes. The drilling complex is removed from the drilling point, loaded into the carrier boat. The carrier boat goes to the base. All drilling operations will be performed automatically.

The claimed laser hardening method makes it possible to drill wells on the seabed automatically, without human intervention, since the “setting” effect is eliminated and drill pipe unscrewing is not a problem.

Claims (1)

A method of laser surface hardening of the threaded part of drill pipes made of titanium alloys, including laser irradiation of the threaded part of drill pipes, characterized in that after laser irradiation, the threaded parts of the pipes are run-in by cyclic screwing-unscrewing, and the tightening torque for screwing is set within 90- 110% of the maximum operational load of the pipes, and the number of cycles is set within 5-10.