GB2277704A - Method and device for welding pipes to each other - Google Patents

Abstract

A method of welding at least two pipes (9) e.g in laying a pipeline. The pipes (9) are held mutually coaxial with a device having a guide ring (7) arranged around at least one of the pipes (9). A carrier (14) of at least one welding torch (63) is guided by the guide ring (7) for movement imparted by a motor (36). Signals from the motor indicate the angular position of the welder which is controlled consequently by a computer. <IMAGE>

Description

METHOD AND DEVICE FOR WELDING PIPES TO EACH OTHER The invention relates to a method for welding to each other at least two pipes held mutually coaxially, wherein a guide ring is arranged round at least one of both pipes and wherein a carrier of at least one welding torch guided by the guide ring is moved in peripheral direction of the pipes while at least one welding bead is applied.

The invention has for its object to facilitate the welding operations and/or to enhance the quality of the weld. To this end one or more of the characteristics of claims 1-6 are applied.

The invention also provides a device which is specially intended for applying the method according to the invention and which has one or more of the characteristics of claims 7-13.

The present invention can be applied in the welding of boilers and vessels, wherein an annular weld is applied between two elements designated as pipes with cylindrical edges. The invention can however be applied with particular advantage in a method and a device for laying a pipeline as described in US-A-5 044 825, the content of which should be deemed as interpolated herein.

According to the invention pipes 9 are herein welded to each other with application of the method and device according to the invention described hereinafter with reference to the drawings.

In the drawings: Figure 1 shows a perspective view of a preferred embodiment of the device according to the invention; figure 2 shows on a larger scale a perspective view of detail II of figure 1; figure 3 shows on a larger scale a section along the line III-III in figure 2; figure 4 shows on a larger scale a perspective view according to arrow IV in figure 2; figures 5 and 6 show on a larger scale a view according to arrow V in figure 1 in respectively the welding position and the rapid displacement position; figure 7 shows on a larger scale a perspective view of a guide ring (detail VII of figure 1); figure 8 shows a control diagram of the device of figure 1; and figure 9 is a schematic view of a welding station of the device of figure 1.

Figures 1 and 9 show a welding station 2 such as a number, for instance six, are present on board a marine pipe-layer to apply welding beads in the annular weld joints 6 of a pipe string 3 which is moved in lengthwise direction of the pipe-layer in arrow direction 1 and which is supported at mutually spaced locations by roller supports 41.

The welding station 2 is formed by a trolley which is guided along rails 3 and which is fixedly clamped to the moving pipe string 3 using a saddle 4 which is pressed against pipe string 3 by means of a height-adjustable leg 5. Close to the weld joint 6 a guide ring 7 (figure 7) is fixedly clamped to one of both pipes 9 for welding to each other, which ring consists of two ring halves 8 mutually connected for pivoting by means of a hinge 10. In the opened position the guide ring 7 can be removed from a pipe string 3. In the closed position the ring halves 8 are mutually locked with a clamping lock 11. Guide ring 7 can be adapted to diverse pipe diameters by means of adjusting blocks 12a and fixed blocks 12 which are fastened alternately and spread over equal angular distances by means of screws 13 to the guide ring. The adjusting blocks 12a each consist of a holder 112 held fixedly against guide ring 7, in which holder is slidably arranged a radially movable support block 113 which is pressed radially inward by rigid springs 114, for instance conical spiral springs. The guide ring 7 is automatically centered herewith and automatically adapted as far as possible to non-round portions and diameter differences. Guide ring 7 can carry two torch carriers 14 and even three or four in the case of large pipe diame ters. The welding station 2 moving reciprocally on the work deck 104 is coupled to a cable guide chain 105 shown in figure 9 which rises from a cable channel 106 located under the work deck 104 and guides a bundle 107 of electrical lines and gas and water hoses from a fixed connection 108 to a station connection 109.

A welder (a welding person) preferably has his own torch carrier 14 and remains therewith at a determined welding station 2. Standing still on his welding station 2 moving along with the pipe string 3 he can concentrate properly on the welding melt and adjust this easily by means of a hand control 88 not connected to the welding torch 63. When a weld joint 6 arrives at his welding station 2 the welder arranges his torch carrier 14 on the guide ring 7. Two roller bearings 15 are guided with pins 16 in the chassis 17 of torch carrier 14 and their rollers 21 are pressed by springs 18 into a guiding groove 19 of guide ring 7. Present on the opposite side of guide ring 7 are two roller bearings 20 which are pivotable on pivot axes 22 relative to chassis 17 by means of a rotating wing 23 which engages on their arms 24 and which can press the roller bearings 20 with their rollers 26 to the guiding groove 27 counter to the action of spring 25. For this purpose the rotating wing 23 mounted rotatably in the chassis 17 is provided with a lever 28 which is pivotable from a release position 28a beyond a stop 30 for pressing in counter to spring action as according to arrow 29 into the locking position 28c. A motor carrier 31 (figure 2) is arranged pivotally about an axis 32 on the chassis 17 and is pulled by a draw spring 33, the tension of which is adjustable with tensioning means 34, against a stop 35. Motor carrier 31 supports a chassis motor 36 which drives a hardened steel drive pinion 37 provided with small teeth which is in frictional engagement with a mild steel gripping ring 38. This gripping ring 38 consisting of two halves is fixed to guide ring 7 by means of clamping pieces 39. In the release position 28b of lever 28 defined by the stop pin 30 the chassis 17 is pressed by the springs 18 so far away from the guide ring 7 as according to arrow 40 that the pinion 37 moves from the engaging position of figure 5 into the position of figure 6 not engaging the gripping ring 7, in which position the torch carrier 14 can be quickly displaced by hand through a considerable distance. The chassis motor 36, which therefore does not have to bring about a rapid chassis driving, can thus be chosen with small dimensions.

A lift 43 is guided slidably in substantially radial direction 44 of the pipes 9 along columns 42 fixed to chassis 17 and is displaced in this direction 44 by means of a lift motor 45. The latter drives the lift 43 by means of a screw 46 with ball screw bolt 47. A cylinder 51 fixed to the motor housing 48 of an oscillation motor 49 is mounted for pivoting on an axial axis 50 which is parallel to the pipes 9. This cylinder 51 is connected to a radial arm 52 with a fork end 53 in which a ball screw drive bolt 54 engages by means of two rollers 55. Drive nut 54 is driven in radial direction 44 via a screw 56 by a tilt motor 57. A sliding cylinder 58 is guided slidably inside cylinder 51, while mutual rotation between cylinders 51 and 58 is avoided by means of a keyed connection 59. The pivoting of the arm 52 effected by the tilt motor 57 is thus transmitted via the keyed connection 59 to the sliding cylinder 58 which bears on its free end a torch holder 60 which has a wedge-shaped cavity 61 for receiving the wedge 62 of a welding torch 63. When this latter is arranged as according to arrow 64 in the torch holder 60 the wedge 62 can be clamped additionally firmly by means of an eccentric 67 to be operated by two levers 66.

The oscillation motor 49 drives the cylinder 58 reciprocally parallel to axis 50 by means of a screw 68 and ball screw bolt 69.

The described mechanism is accommodated in a housing 70 with hand-grip 75 fixed to the chassis 17, wherein the cylinder 58 protruding therefrom is sealed relative to the housing 70 in respect of the radial movement.

Each of the motors 36, 45, 49 and 57 is provided with an associated encoder 36a, 45a, 49a and 57a respectively which registers and transmits to the computer 77 any rotation of the associated motor to an accuracy of for instance 0.010. An angle measuring device 78 suspended from the chassis 17 and operating on the force of gravity is further connected to an encoder 78a which transmits the angle of inclination of the torch carrier 14 to the computer 77.

The welding torch 63 is fed with welding wire 80 via a suspended hose 84 (which also carries a shield gas and cooling water to the welding torch 63) from a supply roll 82 disposed on the platform 81 of welding station 2 by means of a permanent magnet motor which is digitally controlled by computer 77 and which drives a drive mechanism 83 comprising four rollers.

The motors 36, 45, 49 and 57, which consist of DC motors, are each fed separately with electric current from a control box 85 via a cable 86 and a plug connection 87. The information from the angle encoders 36a, 45a, 49a and 57a is transmitted along the same cable 86 and plug connections 87 to a computer 77 accommodated in control box 85.

A hand control 88 is connected to control box 88 for each of both torch carriers 14. The off-button 90 serves to switch this hand control 88 on and off. When hand control 88 is switched on the welding torch 63 can be displaced to a determined position without it functioning. With the pass buttons 91 and 92 one of the different welding processes is chosen for the first, second, third, fourth, fifth or sixth welding bead. The lift motor 45 is operated with the arrow buttons 93. The oscillator motor 49 is operated with the arrow buttons 94 to displace the welding torch 63 slightly to the one or the other side of the weld joint 6. The current to motor 36 adjusted by the computer 77 is changed with the TR buttons 95 to increase or decrease the displacement speed of the torch carrier 14. With the OW buttons 96 the oscillation width set by computer 77, that is, the reciprocal path imposed by the oscillation motor 49 on the welding torch 63, is lengthened or shortened. With the WF buttons 97 the welding wire speed set by computer 77 which is imposed by drive mechanism 83 on the welding wire 80 is increased or decreased. With the Volt buttons 98 the welding wire voltage set by computer 77 is increased or decreased. All these corrections to the welding program entered into computer 77 to be performed using the hand control 88 are only possible up to predetermined limits likewise entered in that welding program, unless a site-foreman operating the computer 77 imposes a changed welding program on computer 77. By pressing in starter button 99 respectively stop button 100 the welding process with the associated welding torch 63 is respectively started or stopped.

To initiate a welding process the lever 28 is placed in the position 28c, the welding torch 63 is set with the hand control 88 in the required position relative to the weld joint 6 and the program for the welding bead to be applied is selected by means of buttons 92. Only then is the. start button operated. This has the result that: 1. The information relating to the original angle of inclination of angle measuring device 78 is stored in computer 77 which then computes continuously the momentary angle of inclination of the torch carrier 14 during applying of a welding bead by calculating the arc travelled by the torch carrier 14 along the gripping ring 38 and then continuously imposes on the welding torch 63 the ideal welding conditions prescribed by the welding program for this momentary angle of inclination.

2. Shield gas is immediately supplied.

3. The welding wire 80 is placed under voltage a little later.

4. The motors 36, 45, 44 and 57 and the drive mechanism 83 then begin to operate.

5. Cooling water is supplied to the welding torch 63.

6. As described above, the welder controls the welding melt with the hand control.

7. When the end of the welding bead to be applied has been applied the welding process is ended by pressing stop button 100.

In the case of a lever 28 then swung into the position 28b the torch carrier 14 can be carried back quickly to a starting position for the following welding bead.

Herein the welding program of a higher located welding bead is also selected with a P-button 92. If the applied welding bead is the last one for the relevant welding station 2, the torch carrier 14 is taken from the guide ring 7 after the lever 28 has been placed in position 28a. With the same position 28a the torch carrier 14 is later placed on a guide ring 7 of a following weld joint 6.

During a welding process the computer 77 deduces on the basis of the voltage of welding wire 80 the distance between welding wire end and the welding melt and varies the voltage and/or the speed of the welding wire feed in order to adjust the conditions prescribed by the program to obtain the intended welding bead thickness.

The welding program entered into the computer 77 can be selected with unlimited latitude. The most ideal parameter can be selected for each momentary angle of inclination. This is particularly important on the underside of the pipes 9.

Although supply of water is not necessary at the set current intensity in the order of magnitude of 180-220 amperes, water cooling is nevertheless preferred in order to lengthen the standing time of the welding torch.

The computer program also controls the position of a switching valve (not shown) for selected feed of a determined gas or gas mixture as a choice from a number of available gas types or gas mixture types, such as for instance C02, 80% Argon + 20% C02 or 100% Helium, this subject to the relevant welding bead to be applied.

The welding voltage is realized by means of a welding current transformer 76 which converts an AC or DC current into a DC current of for instance 450 amperes with a constant low voltage.

All the individual computers 77 belonging to the torch carriers 14 are fed with a welding program and can each separately undergo a program change through local input 110, but can also have a program change imposed from a central computer (109) to which they are all connected. Via information lines the control of each weld performed for the welders is entered into a central computer 109 so that the head welder has available the necessary information.

Claims (15)

1. Method for welding to each other at least two pipes (9) held mutually coaxially, wherein a guide ring (7) is arranged round at least one of both pipes (9) and wherein a carrier (14) of at least one welding torch (63) guided by the guide ring (7) is moved in peripheral direction of the pipes (9) while at least one welding bead is applied, characterized in that the welding torch (63) is moved relative to the guide ring (7) by means of at least one controlled rotary motor (36, 45, 49, 57).

2. Method as claimed in claim 1, characterized in that the rotational movement of the motor (36, 45, 49, 57)-is registered with an angle encoder (36a, 45a, 49a, 57a) which is connected to a computer (77).

3. Method as claimed in claim 1 or 2, characterized in that a plurality of pipes (9) of the same pipe string (3) are welded to each other simultaneously at a plurality of welding station (2), which pipe string (3) is displaced in its lengthwise direction along the plurality of welding stations (2) and wherein per welding station (2) at least one carrier (14) of at least one welding torch (63) is arranged in each case on a guide ring (7), is displaced along this guide ring (7) during applying of a welding bead and is removed from the guide ring (7) before this guide ring (7) is displaced with the pipe string (3) to the following welding station (2).

4. Method as claimed in any of the foregoing claims, characterized in that at least one carrier (14) of at least one welding torch (63) is displaced along the guide ring (7) by means of a pinion (37) which is driven by a motor (36) and which during applying of a welding bead is held with spring force in engagement against a friction ring (38), and which is preferably held out of engagement of the friction ring (38) during displacing of the carrier (14) with non-welding welding torch (63) in peripheral direction of the pipes (9).

5. Method as claimed in any of the foregoing claims, characterized in that the welding process of at least one welding torch (63) is controlled by computer, while the conditions adjusted by the computer are changed fractionally by human intervention.

6. Method as claimed in any of the foregoing claims, characterized in that each time a welding bead is applied an original angular position of at least one carrier (14) of at least one welding torch (63) is registered at the start of a welding bead and that at least one welding condition of the said welding torch (63) is set by the computer (77) subject to the angular position occupied by the carrier (14) and computed by means of the computer (77) by calculating the original angular position and the path travelled by the carrier (14).

7. Device for welding to each other at least two pipes (9) held mutually coaxially while applying the method of any of the claims 1-6, comprising at least one guide ring (7) for arranging round at least one of both pipes (9) and at least one carrier (14) of at least one welding torch (63) guidable in peripheral direction of the pipes (9) by the guide ring (7), characterized by at least one rotary motor (36, 45, 49, 57) driving the welding torch (63) relative to the carrier (14), controlled by a computer (77) and provided with an angle encoder (36a, 45a, 49a, 57a).

8. Device for welding to each other at least two pipes (9) held mutually coaxially while applying the method of any of the claims 1-6, comprising at least one guide ring (7) for arranging round at least one of both pipes (9) and at least one carrier (14) of at least one welding torch (63) guidable in peripheral direction of the pipes (9) by the guide ring (7), characterized in that the guide ring (7) has a gripping profile for first guiding means (21) on its one side and second guiding means (22) on its other side, and that the first and second guiding means are arranged on the carrier (14) for displacement toward and away from each other between a locked guide position and a removal position.

9. Device as claimed in claim 8, characterized in that a drive pinion (37) mounted on the carrier (14) does engage on a gripping rim (38) of the guide ring (7) in a relative driving position of the guiding means (20, 21) and does not engage thereon in a relative free position of the guiding means (20, 21).

10. Device for welding to each other at least two pipes (9) held mutually coaxially while applying the method of any of the claims 1-6, comprising at least one guide ring (7) for arranging round at least one of both pipes (9) and at least one carrier (14) of at least one welding torch (63) guidable in peripheral direction of the pipes (9) by the guide ring (7), characterized in that the welding torch (63) is controllable by a computer (77), wherein the conditions adjusted by the computer (77) can be fractionally changed by means of manually operable control means (88).

11. Device for welding to each other at least two pipes (9) held mutually coaxially while applying the method of any of the claims 1-6, comprising at least one guide ring (7) for arranging round at least one of both pipes (9) and at least one carrier (14) of at least one welding torch (63) guidable in peripheral direction of the pipes (9) by the guide ring (7), characterized in that the welding torch (63) is controllable by a computer (77) subject to an angular position which is computed by the computer (77) by calculating the original angular position of the carrier (14) registered by an angle measuring device (78) when application of a welding bead is initiated and the path travelled by the carrier (14) from this original angular position.

12. Device for welding to each other at least two pipes (9) held mutually coaxially while applying the method of any of the claims 1-6, comprising at least one guide ring (7) for arranging round at least one of both pipes (9) and at least one carrier (14) of at least one welding torch (63) guidable in peripheral direction of the pipes (9) by the guide ring (7), characterized in that the carrier (14) comprises a lifting platform (43) which is displaceable relative to a chassis (17) of the carrier (14) in substantially radial direction of the guide ring (7) by means of a preferably flat rotary motor (45) controlled by a computer (77) and by means of a screw spindle (46), that a tilting arm (51) of the welding torch (63) extending substantially in axial direction of the guide ring (7) is mounted rotatably in the lifting platform (43) and is pivotable via a transverse arm (52) by means of a rotary motor (57) controlled by the computer (77).

13. Device for welding to each other at least two pipes (9) held mutually coaxially while applying the method of any of the claims 1-6, comprising at least one guide ring (7) for arranging round at least one of both pipes (9) and at least one carrier (14) of at least one welding torch (63) guidable in peripheral direction of the pipes (9) by the guide ring (7), characterized in that a chain (105) bendable in a U-shape is arranged as cable and/or hose guiding between a cable and/or hose connection (109) arranged on the welding station (2) and a fixed cable and/or hose connection (108).

14. A method of welding pipes substantially as described wherein, with reference to and as illustrated in any one or more of the Figures of the acaoanying drawings.

15. A welding device or welding station incorporating such a device, substantially as described herein with reference to and as illustrated in any one or more of the Figures of the accaEying drawings.