This invention applies to the submerged arc welding sector. More specifically, the invention relates to an automated submerged arc welding plant, aimed at the steel construction industry.

In more detail, the invention relates to a plant for welding steel beams with a T or H profile.

Plants for welding H beams are currently present on the market comprising several apparatuses together, making it necessary to use a gantry crane in almost all the stages of the process for assembling and handling a partially made profile (Figures 1 -7 attached).

In short, the use of an area of approximately 400 m2 is needed for housing a plant 10 comprising: the infeed rollers 1 with the support cages 2, the outfeed rollers 3, the welding assembly 4 and the gantry crane 5 in front of them.

In fact, in order to make beams with an H profile, a first flange 6 is initially positioned on the infeed rollers 1 , the web 7 is arranged perpendicularly and centrally to the flange 6, these two elements 6 and 7 are blocked in their reciprocal position by the support cages 2, and the two elements 6 and 7 are slid towards the welding assembly 4 (in the direction of the arrow F). As the two elements 6 and 7 slide on the infeed rollers 1 towards the welding assembly 4, the welding assembly 4 carries out, by means of the welding heads 9, the two welds at the two joining edges between the flange 6 and the web 7.

After completion of the welding of the above-mentioned elements 6 and 7, the T profile obtained in this way (comprising a single flange 6 and the web 7) is turned over, and the attachment system 15 of the gantry crane 5 then picks up the T profile and places it again on a new flange 8 on the infeed rollers 1 , moving it in the direction of the arrows G, opposite to the arrows F.

At this point, the steps described above are repeated until the welding of the second flange 8 to the web 7 along the two joining edges. However, as well as the need for a significant production space for housing the gantry crane as well as the plant, the current system has a certain degree of danger during the step for tilting the T profile, as it is complex to control.

Another risk of accidents occurs during the step for transferring the T profile by means of the gantry crane 5, from the tilting means 1 1 of the outfeed rollers 3 to the infeed rollers 1 .

Moreover, a drawback is given by the noise exceeding 85 Decibels during the step for tilting the T profile.

A further drawback is given by the wear of the tilting levers made of steel, which require frequent maintenance.

Since the movement by means of the gantry crane requires a certain time, the productivity of the plant is adversely affected, with obvious down times. Yet another drawback is due to the fact that the control of so many apparatuses is so complex that it requires the presence on the production line of three operators.

There is therefore the need on the market for a welding plant for beams with an H profile with a high productivity, without down times and which allows the production space available to be optimised.

The aim of the plant and the method according to the invention is to overcome the above-mentioned drawbacks and obtain a production plant and a relative method which is efficient from the point of view of production times and the space occupied, as well as for the control of the risk of accidents during their use.

The object of the invention is therefore a welding assembly designed to be positioned in line between first rollers and second rollers of a plant for the welding of steel beams with an H profile (starting from a first flange, a web and a second flange to be welded together).

The invention provides for the welding assembly to rotate about itself on a support surface by 180 ° about a relative vertical axis (perpendicular to the support surface), in such a way as to receive the web, the first flange and/or the second flange, both when coming from the first infeed rollers and when coming from the second outfeed rollers. Preferably, the invention can comprise chain operated tilting means, for tilting the first flange and the web by 180 ° on the second rollers with precision and control of the movement, without requiring the intervention of an operator.

Another advantage is given by the reduction of the noise and the risk of accidents, because the movement of the beam is controlled and accurate. Moreover, the invention can also comprise suspension means equipped with hydraulic telescopic arms, to keep suspended in position the first flange and/or the web when in movement, after tilting.

This allows, advantageously, the operations for centering and alignment of the web on the second flange to be performed in an easy and safe manner.

Another object of the invention is a plant for the welding of steel beams with an H profile (which can be made as described above), comprising first rollers and second rollers and the above-mentioned welding assembly positioned in line between the first rollers and second rollers.

Advantageously, therefore, it is possible to eliminate the presence of the gantry crane and to move the beam simply by means of the rollers themselves; consequently with a considerable reduction in space, as well as a reduction in time.

According to the invention, the plant can comprise support cages for supporting and centring the web with respect to the first flange, each equipped with a hydraulic clamp for their actuation. In this way, the force exerted is not only greater but also uniform along the entire beam, facilitating the alignment and centring operations.

Another object of the invention is a method for welding steel beams with an H profile starting from a first flange, a web and a second flange, characterised in that it comprises the following steps:

- receiving the first flange on first rollers

- positioning the web perpendicularly to the first flange and centrally with respect to it (in this obtaining a beam with a T profile, given by the first flange and by the web) - passing the T profile (where the term "T profile" means the above- mentioned beam, which has a cross section with such a profile) inside a welding assembly and simultaneously welding the first flange to the web

- resting the T profile on second rollers

- tilting the T profile by 180 ° with respect to a horizontal plane

- rotating the welding assembly by 180 ° about its vertical axis

- inserting the second flange beneath the turned T profile, positioning the web perpendicular to the second flange and centrally with respect to it (in this way, a beam is obtained with an H profile given by the first flange, the second flange and the web)

- passing the H profile inside the welding assembly rotated in this way and simultaneously welding the second flange to the web.

The method advantageously allows the production to be considerably reduced, eliminating the down time due to the transport by means of the gantry crane of the T beam in the intermediate processing step.

Further characteristics and advantages of the plant and the method, according to the invention, will more fully emerge from the description that follows, relative to a preferred embodiment thereof given by way of non- limiting example, and from the appended drawings, in which:

- Figure 1 is a schematic front view of a production line, in a first step, according to the prior art;

- Figure 2A is a schematic front view of the production line of Figure 1 , in a second step;

- Figure 2B is a cross-section of a detail of Figure 2A;

- Figure 3A is a schematic front view of the production line of Figure 1 , in a third step;

- Figure 3B is a cross section of a detail of Figure 3A, with tilting means shown in the initial position with a continuous line and in intermediate positions with a dashed line;

- Figure 4 is a schematic front view of the production line of Figure 1 , in a fourth step, with welding elements shown in intermediate positions with a dashed line; - Figure 5 is a schematic front view of the production line of Figure 1 , in a fifth step;

- Figure 6A is a schematic front view of the production line of Figure 1 , in a sixth step;

- Figure 6B is a cross-section of a detail of Figure 6A;

- Figure 7 is a top view of the production line of Figure 1 , with gantry crane and the elements to be welded shown in intermediate positions with a dashed line;

- Figure 8 is a schematic front view of a production line, in a first step, according to the invention;

- Figure 9A is a schematic front view of the production line of Figure 8, in a second step;

- Figure 9B is a cross-section of a detail of Figure 9A;

- Figure 10A is a schematic front view of the production line of Figure 8, in a third step;

- Figure 10B is a cross section of a detail of Figure 10A, with tilting means and elements to be welded shown in the final position with a continuous line and in intermediate positions with a dashed line;

- Figure 1 1 A is a schematic front view of the production line of Figure 8, in a fourth step;

- Figure 1 1 B is a cross section of a detail of Figure 1 1 A, with lifting means and elements to be welded shown in the final position with a continuous line and the tilting means shown with a dashed line;

- Figure 12A is a schematic front view of the production line of Figure 8, in a fifth step;

- Figure 12B is a cross-section of a detail of Figure 12A;

- Figure 13 is a top view of the plant of Figure 8;

- Figure 14 shows a first detail of the plant of Figure 8, unloaded;

- Figure 15 shows the detail of Figure 14, with a first element loaded;

- Figure 16 shows the detail of Figure 14, with a second element loaded;

- Figure 17 shows the detail of Figure 16, with a cages closed;

- Figure 18 shows an enlargement of Figure 17; - Figure 19 shows the enlargement of Figure 18, with hydraulic clamp actuated;

- Figure 20 shows a second detail of the production line of Figure 8, with elements to be welded entering the welding assembly;

- Figure 21 shows a third detail of the plant of Figure 8, with elements to be welded in a first position;

- Figure 22 shows the detail of Figure 21 , with elements to be welded in a second position;

- Figure 23 shows the detail of Figure 21 , with elements to be welded in a third position;

- Figure 24 shows the detail of Figure 21 , with elements to be welded in a fourth position;

- Figure 25 shows a fourth detail of the plant of Figure 8, with welding assembly rotating;

- Figure 26 shows a fifth detail of the plant of Figure 8, with elements to be welded in the welding assembly;

- Figure 27 shows a sixth detail of the plant of Figure 8, with elements welded.

With reference to the above-mentioned Figures 8-27, the plant 100 according to the invention comprises: first rollers 101 , support cages 102, second rollers 103, preferably which can be raised, and a welding assembly 104 placed in line between the first rollers 101 and the second rollers 102.

The welding assembly 104, according to the invention, is able to rotate about itself by 180 ° about the relative vertical axis, in the direction of the arrows I (Figures 1 1 and 13). Advantageously, this allows the welding assembly 104 to receive a series of elements 6, 7, 8 to be welded together, coming both from the first rollers 101 and from the second rollers 103.

In this way it is possible, advantageously, to carry out the processing both in one direction and in the opposite direction, with obvious savings in time. Preferably, the welding assembly 104 comprises chain operated tilting means 1 1 1 for tilting the T profile by 180 ° on the second rollers 103. This guarantees, advantageously, the control and the precision of the movement, reducing the risk of accidents during tilting.

Another aspect of the invention relates to the possibility of keeping the T profile tilted in this way in position, on the second flange, using the suspension means 1 12 equipped with hydraulic telescopic arms, in such a way as to advantageously increase the stability of the elements to be welded, and reducing to a minimum the risks of unbalancing.

Operatively, with reference to Figures 14-27, the first rollers 101 are initially unloaded and the support cages 102, for supporting the webs 7 in position, are open (Figure 14).

The loading operations start with the loading of the first flange 6 on the first rollers 101 (Figure 15).

Once the first flange 6 is in position on the first rollers 101 , the web 7 is positioned on the support cages 102 (Figure 16) and they close (Figure 17).

A preferred variant embodiment of the invention comprises a hydraulic clamp 1 13 for actuating the support cages 102, in such a way that the web 7 is aligned and centred correctly with respect to the first flange 6 (Figures 18 - 19).

Once the web 7 has been centred with respect to the flange 6, this set of elements forms a T, which is inserted in the welding assembly 1 04, and the welding of the T starts (Figure 20), whilst this passes through the welding assembly and rests on the second rollers 103, raised.

After the first welding step has been completed, that is, when the T is resting completely on the second rollers 103, the latter lower downwards (Figure 21 ), moving the first flange 6 into contact with the chains of the 1 14 tilting means 1 1 1 .

When the tilting means 1 1 1 are actuated these open whilst the chains rotate in one direction, and the T is tipped initially by 90 °, moving the first flange 6 in a substantially vertical position, and the web 7 in a substantially horizontal position, with the non-welded end of the web 7 in contact with the chains 1 14 of the tilting means 1 1 1 (Figure 22). When the tilting means 1 1 1 are closed, the chains 1 14 continue to rotate in the same direction, moving the first flange 6 upwards and the web 7 in a vertical position. The suspension means 1 12, preferably by means of the telescopic arms 1 16, therefore keep the first flange 6 perfectly horizontal and the entire T slightly suspended (Figure 23).

In this position it is possible to insert beneath the T the second flange 8 (Figure 24), and to centre in position the second flange 8 with respect to the web 7, in order to create an H profile.

The welding assembly 104 rotates about the relative vertical axis in the direction of the arrow I, by 180 ° (Figure 25), in such a way as to receive the H profile coming from the second rollers 103.

The H profile may therefore move again towards the welding assembly 104 for the welding of the second flange 8 to the web 7 (Figure 26), and then rest on the first rollers 101 (Figure 27).

The invention described can be modified and adapted in several ways without thereby departing from the scope of the inventive concept.

Further, all the details can be replaced by other technically-equivalent elements.

Lastly, the components used, providing they are compatible with the specific use, as well as the dimensions, may vary according to requirements and the state of the art.

Where the characteristics and the techniques mentioned in the following claims are followed by reference signs, the reference signs have been used only with the aim of increasing the intelligibility of the claims themselves and, consequently, the reference signs do not constitute in any way a limitation to the interpretation of each element identified, purely by way of example, by the signs numbers.