GB2159748A - Automatic pike welding equipment - Google Patents

Abstract

Orbitary-moving equipment for the automatic welding of pipes (2), comprises a fixed rail (3) onto which a base plate (6) supporting a welding system (16, 17, 18) is rotatably supported by wheels (5), wherein a second complete and autonomous welding system (16', 17', 18') is assembled together with the first one at an adjustable relative distance from each other onto a second supporting plate (8), by fixing them by means of bolts inside slots (10) extending in a circumferential direction relatively to the rail (3), said second plate (8) being hinged (7) onto the end of said supporting base plate (6), it being so possible to swing it to a second-apart position. Also the bobbin (20') of the welding wire (19') for the second welding lance (18') is swingingly mounted by means of an articulated part of an arm (22) kept in its position by means of a locking key. <IMAGE>

Description

SPECIFICATION Improved equipment for the automatic welding of pipes The present invention relates to an orbitrarymoving equipment for the automatic welding of pipes, which shall be referred to hereinunder simply as to "the orbital equipment", which, by producing at the same time by means of two welding lances two superimposed welding string beads during each passage, acclerates, improves, innovates and makes cheaper the automatic operation, both in the upwards and in the downwards directions, of pipes even of large diameter.

The need of accelerating the working cycle in the welding operations in the laying of pipelines intended for the delivery of liquids or of gases, to the purpose of reducing the coats thereof to more and more competitive values and to reduce the required time as far as possible, has involved the development of more and more complex equipment for pipe automatic welding.

From the present state of the art highly efficient orbital equipment are known for the automatic welding of pipes among which is in particular the one disclosed in our prior U.K.

Patent N 1.534.773 granted on March 21, 1979 of whose object the present Patent Application is a considerable improvement.

As it is well known, the orbital equipment being the object of the above mentioned prior Patent is essentially constituted by a rail positioned and fixed around the pipe in a predetermined position around the edge to be welded, as well as by a supporting plate base fastened by means of quick-fastening means on to the edges of the said rail, through four raced wheels intended for sliding, and moved along said rail by a driving knurled pinion cooperating with an edge of the same rail, on said base plate there being mounted, among others, the welding lance, the welding wire feeder and the mechanisms necessary for the adjustment of the position of said lance, as well as for the swinging thereof in the transversal direction relatively to said edge to be welded.

Such an orbital equipment, similarly to all other similar equipments known, allow only one single welding string bead to be obtained during each passage.

In other terms, two superimposed welding string beads can only be obtained in subsequent and spaced times, by means of two different passages.

Hence, due to the fact that the welding of a pipe is always completed by means of the superimposition of a certain number of string beads, as many passages are necessary, as many are the beads to be accomplished.

Purpose of the present invention is precisely to obviate the limitation said, and to provide therefore an orbital equipment allowing the welding to be obtained with a smaller number of passages.

By achieving such a purpose, also a better quality of the welds is obtained.

It has been indeed surprisingly experimentally found that, by effecting the superimposed welding string beads within a short time range from each other, i.e., practically effecting a welding bead when the melting bath of the underlying bead has not yet become completely cold, as it happens with the known art, a weld with optimum characteristics is obtained, in that an easier interpretation of the two superimposed beads is obtained, which improves the metallurgical characteristics and hence also the toughness of the welded joints.

The problem has been hence solved by adopting on a same supporting base plate two welding lance assemblies equipped with positioning and swinging actuation devices as well as with two welding wire feeders, so that by means of a same single travel of the equipment along the edge to be welded, two superimposed welding string beads are obtained, the second bead being effected with a time delay relatively to the first one which is proportional to the distance on the base plate between the two lances said.

On the other hand, it has been observed always in an experimental way that the quality of the weld is also a function of the said time delay, which must therefore be precisely determined in each case, so that, in order it to be possible to control this phenomenon too, it is necessary to envisage the possibility of varying the time interval elapsing between the formation of two subsequent welding beads, so that it be possible to start the second cycle at that precise moment of the first cycle whereat the conditions of temperature and of solidifying conditions of the welding material and of the same pipe are the most suitable to start said second cycle.

To that purpose, the welding lances are not mounted on fixed positions on the supporting base plate, but in such a way that the distance, in the circumferential direction of the rail, of a lance relatively to the other one can be varied as desired, and consequently the said time delay can be varied as desired, and this is achieved by simply fastening the two welding systems by means of bolts housed within slots, which extend in the circumferential direction of the same rail.

As, moreover, the adoption of two complete and autonomous welding systems on a same base plate, whose size of course must not be increased in order not to increase the overall dimensions, which would impair an efficient fastening on to the rail and would make more complex the welding of a circular joint, involves such an accumulation of elements on the said plate, as to render difficult the oper ations of inspection and of cleaning of the welding lance and of the lower parts of the mobile equipment without it being necessary to disengage the whole structure from the fixed rail, according to another feature of the invention the two said welding systems, instead of being mounted on the said supporting base plate, are mounted on a second supporting plate, which is hinged on to an end of the said base plate, and is held in correspondence of its other end by a locking hook mounted on said supporting base plate.

In this way, by disengaging the said locking hook, it is possible to swing apart the said second plate and thus to render easily accessible the lances and the lower parts of the movable equipment mentioned.

Summarizing, the orbitary-moving equipment for the automatic welding of pipes, comprising a fixed portion or rail positioned and fixed around the pipe in a predetermined position relatively to the edge to be welded, as well as a movable portion constituted by a supporting base plate fastened with quickfastening means on to the edges of the said rail through four raced wheels for sliding, and driven along said rail by a driving knurled pinion cooperating with an edge of the same rail, on which base plate a welding system is mounted, constituted by a block supporting the welding lance comprehensive of the devices necessary for the adjustment of its positioning and for its swinging motion, as well as the feeding device of the welding wire, comprising the welding wire bobbin and the mechanism for delivering the same wire, is characterized according to the present invention in that it is provided with an analogous second welding system mounted in a parallel position to the first welding system on said base plate, so that the two welding lances are positioned parallel to each other along the edge to be welded, the two said welding systems being fixed at a mutual adjustable distance by fastening the said supporting blocks with bolts housed within slots extending in the circumferential direction of the same rail, provided on a second supporting plate which is in its turn hinged in correspondence of an end thereof on to an end of said supporting base plate and held in correspondence of its other end by a locking hook for the locking of said supporting base plate.

Moreover, as, due to the limited space available, the addition in a parallel arrangement of a second welding wire bobbin for feeding the second lance would make it impossible the reloading of the wire on the bobbin of the first lance, according to another feature of the present invention, the welding wire bobbin for said second lance is rotatably mounted on an arm articulated and kept in its position by a locking key.

In such a way, by unlocking the key, said second bobbin can be swung apart, thus allowing the first bobbin to be inserted inside its housing.

The invention is now better clarified with reference to the drawings attached, which illustrates a preferred form of practical embodiment, given to only exemplifying and not limitative purpose, in that it shall be always possible to introduce technical of structural modifications always within the spirit of the present invention.

In said drawings: Figure 1 shows in a partial perspective view an orbital equipment according to the invention, mounted on a pipe to be welded; Figure 2 shows in partial perspective view the orbital equipment of Fig. 1, with the welding systems in their swung-apart position; Figure 3 shows in a partial perspective view and on enlarged scale the detail of the mounting system of the second welding wire bobbin, it too according to the invention.

Referring to the drawings, with 1 the edge to be welded is shown of a pipe 2, on to which at a predetermined distance relatively to said edge 1, a circular rail 3 is mounted and fixed, leaning on to said pipe by means of pin-shaped spacers 4.

On the rail 3 a supporting base plate 6 is then fastened, with moving possibility, through four slide raced wheels 5, on an end of whose supporting base plate 6 a second supporting plate 8 is hinged, by means of the rotation pin 7, such second supporting plate 8 being kept into contact with the base plate 6 by means of a quick-release locking hook 9, which, with being mounted at the other end of said base plate 6, causes its hook 9' to interact with the upper surface of the other end of the said second supporting plate 8 (see specifically Fig. 1).

Said second supporting plate 8 is moreover provided with pairs of slots 10, extending in the circumferential direction of the rail 3, within which two supporting blocks, respectively, 11 and 11' are bolted in parallel arrangement to each other. Said blocks 11 and 11', whose mutual distance is clearly adjustable as desired by taking advantages of the length of said slots 10, support two welding systems complete, autonomous and positioned parallel to each other, of which the second one shall be hereinunder marked with the same numbering as of the first one, but provided with a prime.

More specifically, each block 11, 11' sup- ports, with the possibility of the adjustment thereof in the axial direction of the pipe 2 by means of the guide of the knob 12, 12', a frame 13, 13' which is in its turn vertically adjustable in the radial direction by means of the knob 14, 14'. Each frame 13, 13' supports then, with the possibility of swinging movements, whose stroke can be adjusted by means of the knob 15, 1 5', a structure 16, 16' onto which a welding lance 18, 18' is fastened, by means of a projecting arm 17, 17'.

The two lances 18, 18' are positioned in a parallel arrangement relatively to each other along the edge to be welded 1 (see specifically Fig. 1) and are fed with the welding wire 19, 19' which is extracted from its relative bobbin 20, 20' by a driving mechanism 21, 21'.

Finally, the bobbin 20' of the welding wire 19' for the second lance 18', as it can be clearly seen in Fig. 3, is mounted on an arm 22 hinged in 23 on to a bracket 24 which is solid with said block 11'.

Said arm 22, which allows the second bobbin 20' to be swung apart to the purpose of an easy replacement of the first bobbin 20, is then kept fixed in its position by a locking key 25 which is screwed on an extension 26 of said arm 22.

Claims (3)

1. Orbitrary-welding equipment for the automatic welding of pipes, comprising a fixed portion of rail positioned and fixed around the pipe in a predetermined position relatively to the edge to be welded, as well as a movable portion constituted by a supporting base plate fastened with quick-fastening means on to the edges of the said rail through four raced wheels for sliding, and driven along said rail by a driving knurled pinion cooperating with an edge of the same rail, on which base plate a welding system is mounted, constituted by a block supporting the welding lance comprehensive of the devices necessary for the adustment of its positioning and for its swinging motion, as well as the feeding device of the welding wire, comprising the welding wire bobbin and the mechanism for delivering the same wire, characterized in that it is provided with an anologous second welding system mounted in a parallel position to the first welding system on said base plate, so that the two welding lances are positioned parallel to each other along the edge to be welded, the two said welding systems being fixed at a mutual adjustable distance by fastening the said supporting blocks with bolts housed within slots extending in the circumferential direction of the same rail, provided on a second supporting plate which is in its turn hinged in correspondence of an end thereof on to an end of said supporting base plate and held in correspondence of its other end by a locking hook for the locking of said supporting base plate.

2. Orbitary-moving equipment according to claim 1, characterized in that the bobbin of the welding wire of the second welding system is rotatably mounted on an articulated arm, and is kept in its position by a locking key.

3. Improved equipment for the automatic welding of pipes as substantially disclosed and illustrated herein.