B 23 K 26/00

 

The guessed invention falls into fields of materials treating beam techniques and can be used for pipelines laser welding of different assignment in field requirements: desert, steppe, tundra.

Known installation for pipelines laser welding of the corporation " Majestik Laser Systems Ltd. " [1] includes technological laser, control system, system of radiation transporting, consisting from anthropomorphic robot and built in it water-cooled mirrors, technological lens, technological fitting-out, vehicles.

The installation operates as follows. On a signal of a control system the laser is switched on. The radiation, coming out of the laser, is guided to a system of radiation transporting, where sequentially being reflected from mirrors, it is guided to a technological lens. In a lens the radiation is focused and is guided immediately on pipeline welded junction. While anthropomorphic robot carries on a lens on a junction, committing a circular trajectory around of a pipeline. Simultaneously with this motion is carried out a rotational displacement of a lens with the purpose of radiation direction perpendicularly surface of a tube in welding point. Thus, with the help of these two interdependent motions pipeline welding is carried out. All motions, and also laser operation and other systems of installation are regulated with a control system. The technological fitting-out realizes problems of supporting of welded tube and pipeline, of their mutual centering (for this purpose usually will be utilized cranes). The vehicles are used for transportation of technological laser, systems of its operation security, power supply systems, control system.

Disadvantages of given installation are:

1. An optical channel, lengthy and varying during welding. It carries on to variation of a wave front, state of radiation polarization during welding process and, therefore, to a variability of weld quality.
2. With the help of anthropomorphic robot it is impossible practically to make a complete circle around of a tube. Usually it is done in two stages: a semi-circle from above, then – a semi-circle from below (or contrary) is welded. At such technique of welding seam quality is lower, than at continuous welding with a complete circle (two craters will be formed).
3. The system of radiation transporting incorporates 5 mirrors, that demands added cooling system. Besides each of mirrors immerses a part of radiation, falling on them, that for realization of welding process carries on to a necessity of laser power pinch and, in the end, to enhanced rate of electric power consumption.
4. Using of composite anthropomorphic robot in field requirements rises probable number of installation failures in whole and, accordingly, reduces reliability of its operation.
5. The welding is carried out in requirements of atmosphere direct action, that carries on to lowering quality of welds and, therefore, to aggravation of pipeline operation reliability.
6. Necessity before welding of composite and laborious operation of centering of pipelines ends and welded on it tube.

It is known an optical system for laser welding of tubes [2], including three reflecting mirrors and one focusing. Laser beam from a generator is guided on mirror 1, being reflected from it falls on mirror 2, arranged on a carrier, having an opportunity of transposition around of a welded tube on half of its perimeter (180⁰). Being reflected from mirror 2, the beam falls on mirror 3, arranged on annular-shaped chariot such as a cramp, orbital displaced around a tube on 360⁰. From it the beam is guided to a focusing device.

As against the anthropomorphic robot the given system allows to conduct annular-shaped welding continuously.

However system has disadvantages:

1. There is an extended optical channel.
2. There are some water-cooled mirrors.
3. The operation of centering of pipeline ends and welded on it tube is not resolved.

Problems of the invention are: an improvement in quality of a weld at the expense of constant and minimum optical channel, and also at the expense of atmosphere action exception on welding process, a pinch of common reliability at the expense of exception of anthropomorphic robot, mirrors, mirrors cooling system, a pinch of its compactness, a simplification of centering of pipeline ends and welded tube before welding.

Offered installation includes technological laser, control system, technological fitting-out. It has a housing, overlapping pipeline and welded to it tube. In housing central part there is a high-power laser, having an axial bore and radiation outlet on welded junction through gas dynamics window or through technological lens. The installation comprises also drive unit, laser rotating mechanism around of pipeline axis, data unit of junction position determination, extreme parts of a housing - self –moving legs, adjustable in a radial direction, and protective screens.

The availability of a housing, overlapping pipeline and welded to it tube, allows to contain most relevant for welding process devices in a uniform block and makes the installation compact.

Using of self – moving legs in extreme parts of the housing allows to move independently along a pipeline and by that to reduce necessary transport to a minimum. Besides self – moving legs completely eliminate an operation of centering of pipeline ends and welded to it tube. The tube, inlet into installation, having entered in touch with exhibited from each other self-moving legs, is self-centered with a pipeline, which is taking place also in contact with self-moving legs.

Protective screens close a welding zone and an atmosphere action is avoided.

Using in a housing central part of high-power laser, having an axial bore and radiation outlet in a welding zone, drive unit and mechanism of laser rotating around of pipeline axis allows to eliminate from the installation anthropomorphic robot, some mirrors, and mirrors water cooling system. Also this allows to reduce maximum optical channel and to make it with stationary length.

An adjustment of self-moving legs in a radial direction to pipeline axis allows to use the installation for welding pipelines of different diameters.

The installation looks like this (fig. 1, fig. 2 On one end of the pipeline1 installation housing 3 is erected on self-moving adjustable legs 2. From other end of a housing welded tube 4 is inlet. The adjustable legs have the mechanism of their adjustment in radial direction 5. In a central part of installation are arranged: high-power laser 6 with central axial bore and with radiation outlet block 7, drive unit and mechanism of laser rotating around a tube 8, drive unit and radial moving mechanism of radiation outlet block 9, data unit of junction position determination 10. On both housing ends protective shutters 11 are disposed. The laser power supply, application of cooling water and process gases is carried out under service lines 12. The transpositions of power supply source13, systems of laser operation security 14 are carried out with the help of a vehicle 15 (fig. 3). The operation of all systems is ensured with a control system 16.

Mechanisms of laser rotating around pipeline axis and radial moving of radiation outlet block can be different (cone, worm transmissions, screw - nut of a rolling, slide etc.)

The radiation outlet block guides a radiation, generated immediately from the laser, on welded junction and focuses it. It can be a focusing system of reflecting or flow type or gas dynamic window, or the focusing is carried out immediately in a laser cavity and laser output window is simultaneously radiation outlet block.

The technological laser can look like this (fig. 4, fig. 5). The cavity mirrors 17 are arranged on tetragon corners. On tetragon sides a discharge chambers18 are disposed. Near to cavity opaque mirrors 19 is arranged lead-out mirror 20, delivery radiation to radiation outlet block 7.

For a mixed gas pumping will be used pumping means 21, for mixture cooling heat exchangers 22 will be used. The given arrangement ensures an opportunity of bore arrangement inside the laser.

The installation operates as follows. The welded tube 4 is inlet into installation housing 3, disposed on the end of a pipeline1. With the help of self-moving adjustable legs 2 the installation moves from a pipeline on a tube until will work data unit of junction position determination 10. It means, that attached to the laser 6 radiation outlet block 7 sets precisely opposite of welded junction. Further on a signal of control system 16 are switched on drive unit and radial moving mechanism of radiation outlet block 9, and is advanced necessary distance from radiation outlet block up to a junction. After that simultaneously are switched on the laser, drive unit and mechanism of laser rotating around a tube 8, and is carried out process of annular-shaped welding.

In the laser formation of radiation and its amplification transits in the cavity with two opaque mirrors 19 and four intermediate 17. Between intermediate mirrors for discharge security discharge chambers18 (anode and cathode) are arranged. The pumping of a mixed gas is carried out with pumping means 21. The heated mixed gas is cooled with heat exchangers 22. The radiation outlet is carried out through a lead-out mirror 20, which guides it to radiation outlet block.

The availability of protective shutters 11 allows to cover technological process from atmosphere ill effects. For laser operation security and all installation is used transport device 15, having an electric power supply 13, system of laser operation security 14. The connection between installation and vehicle is ensured with a communication cable 12.

After that the laser will pass completely around a tube, it is switched off, and the installation with the help of self-moving adjustable legs moves along newly welded tube up to its edge. There to the installation is jointed new tube, which is engaged with adjustable legs, and by that is ensured a centering with a pipeline. The work cycle is iterated.

If the installation will be used for welding pipelines of different diameters, the necessary arrangement of self-moving roller legs is ensured with mechanisms of their adjustment in a radial direction 5.

What is claimed is:

1. An installation for pipelines laser welding, comprising technological laser, control system, technological fitting-out, characterized in that it has a housing, overlapping a pipeline and welded on it tube, in a central part of which are arranged high-power laser with an axial bore and with radiation outlet through radiation outlet block, drive unit and mechanism of laser rotating around pipeline axis, and housing extreme parts are supplied with self-moving legs and protective screens.
2. The installation according to claim 1, wherein self-moving legs are supplied with the mechanism of adjustment in a radial direction.
3. The installation according to claim 1, wherein the radiation outlet block is supplied with drive unit, mechanism of radial transposition, data unit of junction position determination.

 

 

 

1. V.E.Merchant, Laser welding in the pipeline industry, The Industrial Laser Handbook, 1992-1993 Edition, Springer Verlag New York Inc., USA.
2. Optical system for laser welding of tubes. Application ¹ 2143649, priority 29.06.83, Great Britain, applicant Fairey Engineering Ltd.