DEVICE FOR INTERNALLY BUTT-WELDING PIPES

Abstract: A device for internally butt-welding pipes, of the type comprising a support and guide frame (2) for an annular welding member (3), rotatable coaxially to the pipes (1) to be welded and carrying a plurality of welding units (4) each comprising support means (13, 14; 40, 41; 40A, 41A; 45, 46) for a spool (8, 8A, 8B) on which welding wire (7) is wound, and means (26) for automatically feeding said wire. The support means (13, 14; 40, 41; 40A, 41A; 45, 46) are removably connected to walls (10A, B) of a support frame (10) for the welding units (4) so as to enable said means to be replaced and spools of different type to be used.

Description: Device for internally butt-welding pipes This invention relates to a devices in accordance with the precharacterizing part of the main claim. Known devices of the aforesaid type use a spool of special dimensions, different from those of the spools usually used for the external welding of pipes. This has resulted in numerous problems up to the present time, mainly the fact that two different spool types have to be constantly available, resulting in supply and stocking problems, spools for internal welding being moreover not always easily available as they are of special type. These spools are also of relatively high cost compared with the spools usually used for external welding. Replacing the spool is also relatively lengthy and complicated. As a matter of fact, in the known devices to change a spool first the welding units have to be removed from their welding position to a replacement one and then the spool and, generally also the attached brake, may be removed. It is to be noted that to obtain a good welding a correct position of the welding units is essential and therefore after a change of a spool the position of said units has to be checked and adjusted. Checking or adjusting the welding wire feed means is not easy in the known devices because also for this operation welding units have to be removed from their welding position in order to perform said controls, and this causes the drawbacks mentioned before. Moreover in most devices the configuration of the joints of the brake coaxial to the spool exposes it to frequent damage because to remove the spool the brake must generally also be removed. In known devices of the aforesaid type the welding wire feed means also have considerable drawbacks. This means comprise a motor of particularly sophisticated and costly type, together with two reduction gears, one epicyclic and the other angular. Although the known feed means are highly efficient they have proved difficult to assemble and maintain, and are also of extremely high cost. An object of the present invention is to provide a device for internally butt-welding pipes, in which replacing the spools of the welding units is simplified and does not need the movement of the welding units from their welding position. A further object is to provide a device which enables spools of any type to be used. A further object is to provide a device in which the welding wire feed means may be cecked or adjusted without moving the welding units from their welding position. A further object is to provide a device in which the spools of welding wire may be removed without removing also the brake of the spool. A further object is to provide a device in which the wire feed means are easy to assemble and maintain and are of low cost. These and further objects which will be apparent to an expert of the art are attained by a device in accordance with the characterizing part of the independent claims. The present invention will be more apparent from the accompanying drawings, which are provided by way of non- limiting example and in which: Figure 1 is a partial schematic side view of a device according to the invention; Figures 2,- 3 and 4, to a different scale than Figure 1, are respectively a shematic view from above, a side view taken on the line 3-3 of Figure 2, and a side view taken in the direction of the arrow Q of Figure 1, shown partly sectioned and with a movable arm in two different utilization positions (one positon being shown by dashed lines), of a welding unit according to the invention; Figures 5, 6 and 7 show respectively a schematic view from above,- a side view taken on the line 6-6 of Figure 5,- and a rear view taken on the line 7-7 of Figure 5, of a first modification of the welding unit; Figure 8, 9 show respectively a schematic view from above and a rear view taken on the line 9-9 of Figure 9, of a second modification of the welding unit; Figures 10, 11 show respectively a schematic view from above and a rear view taken on line 11-11 of Figure 10, of a third modification of the welding unit; Figures 12, 13 show respectively a partly sectional schematic view from above and a partly sectional side view taken in the direction of the arrow A of Figures 12, of welding wire feed means. Figure 1 shows a usual device for internally butt-welding pipes 1 (shown partially by dashed lines in Figure 1), of the type comprising a support and guide frame 2 for an annular welding member 3, rotatable coaxially to the pipes to be welded and carrying a plurality (three are shown by dashed lines in the figure) of welding units 4. A device of the aforesaid type has been 'known for some time and will thereofre not be described in detail hereinafter. The welding units 4 shown in detail in Figures 2-11 comprise, fixed in conventional manner to a usual upperly open box support frame 10 with side wals 10A, 10B connected together by cross-members 11A-E, a welding head 9 and means 12 for automatically moving the head from a rest position {Figure 3) to an operating position (not shown) . Said components are all of conventional type to the expert of the art and will therefore not be described in detail hereinafter. The welding unit 4 also comprises a spool 8 on which welding wire 7 is wound and a unit 6 for feeding this wire to the welding head 9. More specifically, with reference to Figures 2-4, the spool 8 is of the type usually used for externally welding pipes and is supported by a pivot 13 (Figure 4) fixed to an arm 14 hinged at 15 to the side wall 10A of the welding unit. The pivot 13 is of the braked type and comprises an outer cylindrical first element 16 on which the spool 8 is mounted and which is connected by bearings 17 to a central member 19 rigidly fixed to the arm 14. At its free end the central member 19 comprises a brake 20 with a screw 21, which can be adjusted to regulate the action of braking jaws 22 acting on the element 16. At its free end this latter is closed by a screw cap 23 acting also as a lateral clamping support for the spool 8. It is to be noted that thanks to the screw cap 23 the braking action is transmitted on the external lateral side 8C of the spool. Moreover advantageously the screw cap has a thread opposed to the sense of rotation of the spool so that it can not be unscrewed from the element 16. The arm 14 is hinged in a manner conventional to the expert of the art at 15 to the side wall 10A of the unit,- is rigidly fixed by two screws 24 (Figure 3) to the pivot 13 and carries at its free end a usual member 25 for locking the arm 14 to the wall 10A. The member 25, of conventional type, comprises a knob 25A which when operated allows a stem 25B to be inserted into or removed from a hole provided in the wall 10A so as to be able to lock the arm 14 to the wall 10A in its operating position (Figure 3) or to allow it to rotate upwards (see arrow B of Figure 3) into a position R (Figure 3) which extremely facilitates the operations involved in replacing the spool 8 and in checking or adjusting the wire feed means 6. By virtue of the arm 14 these operations are considerably simplified, and in fact to change a spool, having raised the arm 14 it is necessary merely to unscrew the cap 23, mount a spool and again lower the arm into position 0. It should also be noted that if non-standard spools are to be used, for examle of the type used up to the present time in known welding units, the pivot 13 has merely to be replaced with another pivot of similar type and suita le size. This is also particularly simple to do, it being necessary merely to unscrew the screws 24 which fix the pivot 13 to the arm 1 . It is to be noted that to change a spool it is no more necessary to move the welding unit from its welding position. Moreover, when the arm 14 is raised there is enough space to perform any required check or adjustment on the feeding means 6 or to other parts of the device positioned in correspondence of the spool. The unit 6 for feeding the wire 7 to the welding head comprises a geared motor unit 26, on the motorized output shaft 27 of which there is_ keyed a first drive wheel 28 (Figure 3) which, cooperating with an underlying idle wheel 29 (shown in Figure 13) , advances the wire 7 towards the head 9. The geared motor unit 26 (Figures 12, 13) comprises an electric motor 30, advantageously of direct current type powered at 24 volts, and of relatively high power compared with that of conventionally used motors, and a worm reducer 31,- with an output shaft 27 on which the drive wheel 28 is keyed to cooperate with the underlying idle wheel 29, which in the illustrated embodiment is a usual bearing for driving the wire 7. It should be noted that the motor 30 ' is of conventional type and is therefore of extremely low cost, is reliable, and is of simple assembly and maintenance, the reducer 31 also being of low cost and extremely simple and reliable compared with the feed unit usually mounted on traditional welding units. Figures 5-9 show two modifications of the welding unit shown in Figures 2-4. Those elements in common with this latter embodiment are indicated by the same reference numerals. The first modification shown in Figures 5-7 comprises a spool 8 of identical type to that shown in Figures 2-4. This spool is however mounted on a braked pivot 40 of different type, snap-fitted to support blocks 41 rigidly fixed to the side walls 10A,- B of the frame of the welding unit. The braked pivot 40 is of conventional type, a similar pivot (indicated by 40A in Figure 8) already being used, but of smaller size, for the spools 8A (Figures 8, 9) , also of smaller size, usually used in known welding units. The support blocks are removably fixed to the side walls 10A, B, by screw 43. Holes, advantageously threaded, for the passage and/or engagement of said screws, are provided in predetermined positions in the side walls for this purpose. Advantageously, in that face facing the spool the blocks comprise a slot 44 for facilitating the insertion of the support pivot 40,- and at their lower end a seat 44A for the snap-engagement of said braked pivot 40. As already stated, the known welding units use a conventional spool 8A of smaller size than the previously described spools 8 (shown in Figures 8-9) . To use this type of spool in the unit of Figures 2-4, it is necessary merely to remove the arm 14 and fix the support blocks 1A to the walls 10A,- 10B. To use it in the unit of Figures 5-7 it is necessary merely to replace the blocks 41 by the blocks 41A. In this manner th various types of spools available can be used in the welding units by means of relatively simple and fast operations. Finallly, Figures 10, 11 show a further modification of the welding unit, in which a spool 8B is arranged with its axis parallel to the side wall 10A, B of the unit frame. For this purpose a bridge support 45 is provided comprising a base wall 45A to which a braked support pivot 46 for the spool 8B is fixed. The base wall 45A is removably fixed, for example by screws 43B, to the side wall 10A, B of the frame. The pivot 46 is advantageously removably connected to the support 45 so as to be able to be easily replaced by another pivot if a different type of spool is to be used. The braked pivot 46 is advantageously of the same type shown in Figure 4; the breaking action is transmitted to the superior wall 8D of the spool 8B by a screw cap 23 of the same type described before. It should be noted that this latter arrangement is particularly advantageous because it considerably reduces the operations required to mount the spool on the support pivot. It is to be noted that a bridge support similar to that represented in figures 10-11 may be fixed also to the movable arm 14, in order to permit also a vertical arrangement of the spools,- on the movable arm. This "vertical" arrangement of the spools limit the height of the welding unit, which is particularly useful for devices required to weld pipes of smaller diameter. Finally it should be noted that the embodiments described heretofore are described by way of example only, and that numerous modifications are possible all falling within the same inventive concept, for example the shape of the movable arm 14 could be different from that shown, as could the means for fixing the blocks 41, 41A, 45 to the walls 10A, B.

Claims: Claims : 1. A device for internally butt-welding pipes (1), of the type comprising a support and guide frame (2) for an annular welding member (3) , rotatable coaxially to the pipes (1) to be welded and carrying a plurality of welding units {4) each comprising support means (13, 14; 40, 41; 40A, 41A; 45, 46) for a spool (8, 8A, 8B) on which welding wire (7) is wound,- and means (26) for automatically feeding said wire, characterized in that said support means (13, 14; 40, 41; 40A, 41A; 45, 46) are removably connected to at least a wall (10A, B) of a support frame (10) of the welding units (4) so as to enable said means to be replaced and spools of different type to be used, said support means (13, 14; 40, 41; 40A, 41A; 45, 46) being shaped in such a way that said spools may be removed without moving said welding units (4) from said welding member (3) . 2. A device as claimed in claim 1, characterized in that the support means comprise a movable arm (14) hinged to one of the walls (10A) of the support frame (10), said arm (14) being hinged to said wall (10A) in such a way that, without moving the welding unit (3) , it can be rotated over and away from said unit (3) when a spool (8) has to be replaced. 3. A device as claimed in claim 2, characterized in that a braked support pivot (13) for a spool (8) is associated to the movable arm (14) . 4. A device as claimed in claim 2, characterized in that the movable arm (14) comprises a member (25) for its stable fixing to the frame (10) when in its operating position (Figure 3) . 5. A device as claimed in claim 2, characterized in that the braked pivot (13) comprises a closure cap (23) screwable to the body of said pivot and also acting as a lateral support for clamping the spool (8) to said pivot. 6. A device as claimed in claim 5, characterized in that the thread of the screw cap (23) is opposed to the sense of rotation of the spool (8) . 7. A device as claimed in claim 2, characterized in that the braked pivot (13) comprises a brake (20) having an adjustment screw (21) cooperating with braking jaws (22) acting on a cylindrical element (16) supporting the spool (6) . 8. A device as claimed in claim 2, characterized in that the movable arm (14) comprises a support (45) comprising a bracked pivot (46) for carrying a spool (8B), said spool having its axis of symmetry substantially perpendicular to the base of the welding unit, the spool hence being positioned vertically. 9. A device as claimed in claim 1, characterized in that the support means comprise a plurality of pairs of support blocks (41, 41A) , each pair being arranged to cooperate with a braked support pivot (40, 40A) for a particular type of spool (8, ' 8A) , said blocks being removably fixed to opposing faces of side walls (10A, 10B) of the frame (10) of the unit (4) . 10. A device as claimed in claim 9, characterized in that in those of their faces facing the spool (8, 8A) the support blocks (41, 41A) comprise a slot (44) for facilitating connection to the support pivot (40, 40A) , and comprise a seat (44A) at their lower end for the snap- engagement of said pivot (40, 40A) . 11. A device as claimed in claim 9, characterized in that the support blocks (41, 41A) are removably connected to the frame by screws (43; 43A) , said screws passing through holes provided in predetermined positions in the walls (10A, B) of the frame (10) of the welding unit (4) . 12. A device as claimed in claim 1, characterized in that the support means comprise a support (45) removably connected to the frame and comprising a braked pivot (46) for carrying a spool (8B) , said spool having its axis of symmetry substantially perpendicularl to the base of the welding unit, the spool hence being positioned vertically. 13. A device as claimed in claim 12, characterized in that the braked pivot (4B) is removably connected to the support (45) so as to be able to be easily replaced if spools of different type are to be used. - 14. A device' as claimed in claim 12, characterized in that the support (45) comprises a base (45A) to which the braked pivot is centrally connected and which is removably fixed to walls (10A, B) of the frame (10) of the welding unit. 15. A device for internally butt-welding pipes, of the type comprising a support and guide frame (2) for an annular welding member (3) , rotatable coaxially to the pipes (1) to be welded and carrying a plurality of welding units (4) each comprising support means (13, 14; 40, 41; 40A, 41A; 45, 46) for a spool (8, 8A, 8B) on which welding wire (7) is wound, and means (26) for automatically feeding said wire and comprising a geared motor unit (30, 31) , characterized in that the reduction gear (31) is of worm type and the motor (26) is a direct current electric motor of relatively high power.

Inventors: BOSIO PAOLO, BOSIO, PAOLO
Applicants: BOSIO PAOLO, PSI PIPELINE SERVICE S A, BOSIO, PAOLO, PSI PIPELINE SERVICE S.A.
Application year: 1996
Main classification: B23K9
IPC codes: B23K37