WO2000041489A2

WO2000041489A2 - Welding machine

Info

Publication number: WO2000041489A2
Application number: PCT/GB2000/000082
Authority: WO
Inventors: Leslie Ernest Power; Reginald Taylor; Michael Anthony Brennan
Original assignee: MELTAX GmbH
Current assignee: MELTAX GmbH
Priority date: 1999-01-13
Filing date: 2000-01-13
Publication date: 2000-07-20
Anticipated expiration: 2001-07-13
Also published as: WO2000041489A3; AU1994200A

Abstract

An internal pipe welding machine including a plurality of arrester assemblies to correctly position the welding machine relative to an end of a pipeline to be welded, each arrester being moveable between a deployed position in which a positioning abutment is capable of abutting the end of the pipeline and a retracted position.

Description

WELDING MACHINE

The present invention relates to welding machines and in particular to internal pipe welding machines.

Welding machines are known in which pneumatic rams situated in front of a welding plane operate to move positioning abutments into a deployed position to enable the machine to be correctly positioned relative to the end of a pipeline. However such positioning abutments rely on there being sufficient air pressure in the rams. Under some circumstances eg. when the pipeline is being laid in an uphill direction and where the air in an air receiver tank situated on the internal pipe welding machine has been depleted as a result of driving the internal pipe welding machine uphill from the previous welded joint, the ram air pressure can be sufficiently low such that misalignment of the pipe welding machine relative to the joint occurs. If such misalignment is not initially noticed and a welding operation takes place some or all of the weld bead will miss the joint between the pipeline and pipe requiring subsequent cutting out of the now welded portion and subsequent correct rewelding, all of which is time consuming and expensive.

According to the present invention there is provided an internal pipe welding machine including a plurality of arrester assemblies to correctly position the welding machine relative to an end of a pipeline to be welded, each arrester being moveable between a deployed position in which a positioning abutment is capable of abutting the end of the pipeline and a retracted position.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which:- Figures 1-5 are successive composite cross-sectional views of an internal pipe welding machine according to the present invention;

Figure 6 is an enlarged view of an arrester assembly of figure 3 shown substantially in isolation for clarity;

Figure 7 is a cross-sectional view of a sleeve guide;

Figures 8 -11 are successive cross-sectional views of the arrester assembly of figure 6;

Figure 12 is a view in the direction of arrow B of figure 6;

Figure 13 is a cross-section view taken along the line C of figure 6;

Figure 14 is a composite view of rod 416;

Figure 15 is a part view of sleeve 412; and

Figure 16 is a developed view of the rotation groove 480.

With reference to figures 1-5 there is shown an internal pipe welding machine 10 positioned within a pipeline 1. The pipeline 1 comprises a series of pipes each of which have been welded together to ensure a fluid tight pipeline. The internal pipe welding machine 10 enables the joint 6 between the end 4 of pipeline 1 and end 5 of adjacent pipe 3 to be welded from the inside. Additionally the joint 6 can be welded from the outside by the use of a separate external pipe welding machine.

The internal pipe welding machine 10 comprises the following major components :-

a) Nose cone assembly 20 b) Thruster assembly 30 c) A plurality of arrester assemblies 40 d) A plurality of automatic welder assemblies 50 e) An articulated joint assembly 60 f) A drive assembly 70 g) An air receiver 80 h) A command rod coupling 85, and i) A chassis 11

The nose cone assembly 20 includes a manual welder 19 including a welding torch 21 along with a spool of welding wire 22. The nose cone assembly 20 includes a plate 23 to which the thruster assembly 30 is connected. The nose cone assembly also includes a plurality of circumferentially equispaced pivotal guide arms 24 (in this case six) which are also connected to the thruster assembly 30.

Thruster assembly 30 includes a plurality of circumferentially equispaced pipe engaging clamps 31, a pair of guide wheels 32 and a rotatable ring member 33.

Mounted on ring member 33 is a plurality (in this case six) of circumferentially equispaced automatic welder assemblies 50.

A plate 61 of articulated joint assembly 60 is attached to the back of the thruster assembly 40. Attached to plate 61 is a plurality (in this case three) of circumferentially equispaced arrester assemblies 40. Each arrester assembly 40 includes an extendable shaft 41 with a positioning abutment 42 at one end.

The articulated joint assembly 60 allows the front subframe 12 of chassis 11 to articulate relative to the rear subframe 13 of chassis 11 and includes an articulated joint 62 and a plurality (in this case two) of loading wheels 63.

A plate 71 of the drive assembly 70 is attached to the back of the articulated joint assembly 60.

Drive assembly 70 includes a plurality (in this case three) of circumferentially equispaced track laying arrangements 72. Drive assembly 70 also includes 2 batteries 73 and a tank 74 of inert welding shield gas. A plate 75 of the drive assembly 70 is connected to the air receiver assembly 80.

The air receiver assembly 80 includes an air receiver tank 81.

At the front of the nose cone assembly 20 there is positioned a command rod rear coupling 85 which is releasably connected to a command rod 86. Command rod 86 is of a length such that it projects beyond the end 3 of pipe 3 and includes at that end a command rod control panel (not shown) which can be used to control various functions of the machine and a command rod front coupling (not shown) which releasably connects the command rod to a supply of services eg. compressed air. battery charging current and welding current generators. Control signals pass down the command rod, to the machine, along with service supplies such as compressed air, welding current, and welding shield gas.

Once the internal pipe welding machine has completed a weld sequence, continued operation of the machine is as follow:-

1) An operator standing at the open end of the pipeline, ie. at the open end of the pipe that has newly been welded into place, adjacent the command rod control panel disconnects the command rod front coupling from the services and then operates the panel so as to retract the clamps and then start the air motors which in turn drive each track drive 72 so as to advance the machine along the pipeline 1 with the front subframe 12 being carried on guide wheels 32. The air motors are supplied by pressurised air from the air receiver tank 81.

The machine is advanced, pushing the control rod before it, the control rod being fed into the next pipe to be welded which has previously been located proximate the end of the pipeline. A wall proximity sensor (not shown) moulded on the machine engages the inner wall of the pipe. When the nose cone assembly 20 projects from the open end of the pipeline 1 to such an extent that the proximity sensor no longer engages the wall, the machine is automatically stopped.

2) The operator further advances the machine by operating a machine control panel (not shown), situated within the nose cone assembly and accessible to the operator, such that the automatic welder assemblies 50 project beyond the open end of the pipeline.

3) The extendable shaft 41 of each arrester assembly 40 is then extended and rotated such that the positioning abutment 42 is axially aligned with a weld plane of the welder assemblies 50 and radially aligned with the end of the pipeline.

4) The operator then reverses the machine until the positioning abutments 42 contact the pipeline and prevent further rearward movement of the machine. At this position the weld plane of the automatic welder assemblies is now aligned with the end of the pipeline (see fig 1).

5) The rearmost pipe-engaging clamps 31A are then deployed to clamp the machine securely relative to the pipeline.

6) Each positioning abutment 42 is then rotated about the axis of the extendable shaft 41, and the extendable shaft is then withdrawn such that each positioning abutment lies between two adjacent rear pipe-engaging clamps 31 A, clear of the path of the automatic welder assemblies (see below). 7) The section of pipe is then moved such that its end to be welded abuts the end 4 of the pipeline.

8) The operator then deploys the front pipe-engaging clamps 3 IB by using the command rod control panel.

9) At some convenient time following stage 1) above of the operation of the machine, and prior to welding (see below) the control rod front coupling is reconnected to the supply of services and the air receiver tank 81 can be re-pressurized if necessary.

10) Welding of the joint 6 between the pipe 3 pipeline 1 then occurs in two stages:

Firstly the automatic welder assemblies positioned at 12 o'clock, 2 o'clock and 4 o'clock (when viewing from the front of the machine) weld the joint 6 whilst the ring member 33 rotates clockwise by approximately 60 degrees to weld one half of the joint 6. It should be noted that the automatic welder assemblies originally positioned at 6 o'clock, 8 o'clock and 10 o'clock are now positioned at 8 o'clock, 10 o'clock and 12 o'clock respectively. These latter automatic welder assemblies are then operated whilst the ring member is rotated sixty degrees anti-clockwise to weld the remaining half of the joint 6.

11) The operator then unclamps the front and rear pipe-engaging clamps via the command rod control panel and the machine can be advanced further along the pipeline to the next weld position. With reference to figures 6-16 there is shown various components of the arrester assembly 40 shown in figure 3.

The major components of the arrester assembly 40 are an actuator 410, (see fig 6) extendable shaft assembly 41 comprising sleeve 412 and rod 416, sleeve guide 414, rod guide 418 and positioning abutment 42.

In this case actuator 410 is a double acting pneumatic actuator, the piston (not shown) of which is connected to piston rod 420. Secured to the end of piston rod 420 is a bobbin 422 having two bobbin flanges 424 separated by a collar 426. The piston rod is operable between a first position as shown in figure 8, which corresponds to a deployed position of the arrester, and a second position as shown dotted in figure 6 at D, which corresponds to a retracted position of the arrester assembly. The piston and piston rod move within a piston cylinder 428, which is secured, at the end remote from the bobbin, to a cylinder plate 430. Cylinder plate 430 is secured to one end of sleeve guide 414 by bolts 431 (only one shown).

Figure 7 shows the sleeve guide 414 which includes a generally cylindrical portion 434 and a flange portion 436. Flange portion 436 is secured by bolts 437 (only one shown, see figure 8) to plate 61 of the articulated joint assembly 60.

The cylindrical portion 434 includes two bush recesses 438, each recess having a bush 438A, and two seal recesses 439, each seal recess having a seal 439A. Slidably mounted within the cylindrical portion 434 of the sleeve guide 414 is the annular sleeve 412. A sleeve end cap 443 is secured to one end 444 of the sleeve v bolts 445 (only one shown). End cap 443 includes a central hole 446 through which rod 416 can pass. Mounted in the central hole 446 is a seal 447.

A connecting means 450 connects the sleeve end cap 443 to the bobbin 422. The connecting means comprises two flanges 451 and a plate 452 welded to the sleeve end cap 443. A bobbin engaging plate 453 is secured to the flanges 451 and plate 452 by welding and has a fork portion 454 which sits between the bobbin flanges 424 and partially surrounds the collar 426. This connecting means therefore prevents rotation of the sleeve 414.

At the end 456 (see figure 10 and 15) of the sleeve remote from the sleeve end cap there is a bush 457 and a seal 458. Proximate end 456 there is a rod engaging ball 460 held axially stationary relative to the sleeve by a conical recess 461 in a ball cap 462. Ball cap 462 is secured to sleeve 412 by bolts 463 (only one shown).

Rod 416 includes a plate 468 (see figure 8) secured to one end by a bolt 468 A. First portion 471 of rod 416 passes through the hole 446 of the sleeve end cap 443 and extend part way along the sleeve up to a second portion 472 of the rod (see figure 14). Second portion 472 includes an abutment 475 against which one end of a compression spring 476 acts, the other end acting against an abutment 448 of sleeve end cap 443.

Second portion 472 is connected via an externally threaded portion thereof 477 to an internally threaded recess 478 of a third portion 473 of the rod 416. The third portion includes a bush 479 proximate the recess 478.

A rotation groove 480 is formed in part of the third portion 473. In this case the groove has two end portions 482 and 483 connected via a helical portion 481. The end portions are axially displaced from one another and also on diametrically opposite sides of the third portion 473 of rod 416.

Ball 460 engages the rotation groove 480 and it can be seen that axial relative movement between the rod and the sleeve will cause the ball to move from end 482 along helical portion 481 to end 483 of the rotation groove thus causing the rod to rotate through 180 degrees relative to the sleeve (see below).

The third portion of the rod 473 has secured on it an extending stop 484 and a retraction stop 485, both of which are rectangular in cross-section (see figure 13, stop 484 shown for comparison). It should be noted that retraction stop 485 is shorter than extending stop 484.

A positioning abutment assembly 487 (see figure 11) is secured via a bolt 487A to the end of rod 416 remote from the plate 468. Positioning abutment assembly 487 includes boss 488 into which abutment bolt 489 is screwed. Abutment bolt 489 is tightened up against an appropriately sized shim 489A.

The third portion 473 of the rod 416 passes through rod guide 418 which is secured to clamp support 324 of thruster assembly 30. Rod guide 418 includes a key hole slot 491 (see figure 13) which has an arcuate portion 491A and a rectangular portion 491B. Rod guide 418 is secured to clamp support 324 by bolts 492 (only one shown). The arcuate portion of key hole slot 491 is sized to be a sliding fit on third portion 473 of rod 416. The rectangular portion of the key hole slot 491 is sized to allow the retraction stop 485 to pass through the rod guide but prevent extending stop 484 from passing through the rod guide (see figure 13).

Each arrester assembly is identical and therefore only the operation of one arrester will be describe in detail.

Figures 6 and 8-11 show the arrester assembly in a deployed position with the abutment bolts 489 abutting the end of the pipeline 1. As described previously, to achieve this position the welding machine has been reversed into the pipeline until contact is made between the abutment bolts 489 on each arrester and the end of the pipe. Once this happens further reversing of the machine is prevented because an abutment surface of the rod guide (also known as a welding machine positioning stop 494, see figure 11) abuts the extending stop 484, causing that poπion of the rod 416 between the extending stop 484 and the positioning abutment 487 to act in tension.

It can be seen the arrangement provides for a positive mechanical stop such that once the arrester assembly is in a deployed position loss of air pressure in actuator 410 will not result in misalignment of the welding machine relative to the end of the pipeline.

Once the rearmost pipe engaging clamps 31A are deployed, the extendable shaft assembly 41 can be moved to its retracted position as follows :-

The actuator 410 is pressurized such that the bobbin is caused to move rearward, away from the cylinder plate 430. This in turn causes the sleeve 412 to also move rearward. Since initially the abutment bolts 489 of the positioning abutment 487 remain engaged with the end of the pipeline 1 the rod 416 cannot move rearward, resulting in relative movement between the rod 416 and the sleeve 412. This causes the ball 460 to move along the rotation groove 480 and since the sleeve cannot rotate (due to the engagement of the fork portion 454 with the bobbin collar 426) the rod is caused to rotate. Even when the positioning abutment 487 no longer aligns with the end of the pipeline eg. after 90 degrees of rotation of the rod, the rod is still prevented from retracting by contact of the retraction stop 485 with an abutment surface of the rod guide (also known as the welding machine retraction stop 495, see figure 11).

Only when the rod 416 has rotated through 180 degrees and the ball 460 is situated in end portion 483 of the rotation groove 480 does the rod retraction stop 485 align with the rectangular portion 49 IB of the key hole slot 491. At this point the plate 468 contacts the sleeve end cap 443 and the rod and sleeve together retract in unison to the retracted position such that the positioning abutment 487 is positioned substantially between circumferentially adjacent rear pipe engaging clamps 31 A.

Thus in moving from a deployed to a retracted position the positioning abutment 487 initially rotates through 180 degrees and then retracts by the distance R (see figure 11). To move from a retracted position to a deployed position, the actuator is pressurized to cause the bobbin to move towards the cylinder plate 430 initially resulting in the rod and sleeve moving in unison until the extending stop 484 of rod 416 contacts the welding machine positioning stop 494 on the rod guide 418 preventing further forward movement of the rod. Continued forward movement of the sleeve causes the sleeve to rotate the rod 180 degrees as the ball move along the rotation groove 480 from end 483 to end 482.

Spring 476 biases the rod forwards relative to the sleeve. Because the axis of the extendable shaft assembly 41 is angled relative to the central line of the pipeline, during the rotation of the positioning abutment assembly from the deployed position, the abutment bolt 489 tends to move axially forwards relative to the centre line of the pipeline. This helps when disengaging the fine adjustment bolts from the end of the pipeline.

It should further be noted that the arrester is positioned substantially within the pipeline (as opposed to the pipe to be welded on) ie. substantially behind the weld plane, when the arrester is in its deployed position and the arrester is completely positioned within the pipeline (as opposed to the pipe to be welded on) ie. completely behind the weld plane, during welding of the pipeline to the pipe to be welded on. Thus by situating the arrester assemblies to the rear of the welder assemblies 50, more space is available to the front of the welder assemblies for other components, in particular those components associated with supplying services to the welder assemblies 50 during welding when the welder assemblies are rotating. The internal pipe welding machine can be used to weld pipelines of different internal diameter, and different sets of positioning abutments can be provided to ensure that an abutment bolt is positioned at the correct radius relative to the pipeline eg. the bosses 488 can be made longer to accommodate larger pipe diameters.

Claims

1. An internal pipe welding machine including a plurality of arrester assemblies to correctly position the welding machine relative to an end of a pipeline to be welded, each arrester being moveable between a deployed position in which a positioning abutment is capable of abutting the end of the pipeline and a retracted position.

2. An internal pipe welding machine as defined in claim 1 in which at least one arrester, when in its deployed position during alignment of the welding machines with the end of the pipeline, is positioned substantially within the pipeline.

3. An internal pipe welding machine as defined in claim 1 or 2 in which at least one arrester, when in its retracted position during welding of the pipeline to a pipe, is positioned within the pipeline.

4. An internal pipe welding machine as defined in any one of claims 1-3 in which at least one arrester, when in its deployed position, is axially fixed relative to a chassis of the internal pipe welding machine by a positive mechanical stop.

5. An internal pipe welding machine as defined in any previous claim in which at least one arrester has the positioning abutment mounted on an arrester rod, the arrester rod acting between the end of the pipeline and a welding machine positioning stop when positioning the welding machine.

6. An internal pipe welding machine as defined in claim 5 in which that part of the arrester rod that acts between the end of the pipeline and the welding machine positioning stop acts in tension.

7. An internal pipe welding machine as defined in claim 5 or 6 in which the arrester rod is at least rotatable about an arrester rod axis when moving between the deployed and retracted positions.

8. An internal pipe welding machine as defined in claim 7 in which the arrester rod axis is not parallel to the pipeline axis.

9. An internal pipe welding machine as defined in any one of claims 7 or 8 in which during a part of the movement of the rod between the deployed position and the retracted position the rod is rotatable through substantially 180 degrees.

10. An internal pipe welding machine as defined in any one of claims 7-9 in which the rod is rotatable by the action of a projection on one of a sleeve of the rod or the rod, engaging a groove in the other of the sleeve or rod.

11. An internal pipe welding machine as defined in claim 10 in which either or both ends of the groove run parallel with the rod axis.

12. An internal pipe welding machine as defined in claim 10 or 11 in which the sleeve moves axially relative to the rod to effect rotation of the rod.

13. An internal pipe welding machine as defined in any one of claims 5-12 in which the rod moves at least substantially axially having regard to the pipeline axis when moving between the deployed and retracted positions.

14. An internal pipe welding machine as defined in claim 13 in which the axial movement ceases when an extending stop on the rod contacts a welding machine positioning stop.

15. An internal pipe welding machine as defined in claim 13 or 14 when dependent on claim 10 in which the rod and sleeve move substantially axially in unison during at least a part of the movement of the rod between the deployed and retracted position.

16. An internal pipe welding machine as defined in any one of claims 5-15 in which the rod is biased to an extended position by biasing means.

17. An internal pipe welding machine as defined in claim 16 when dependent upon any one of claim 10-15 in which the biasing means acts on the sleeve.

18. An internal pipe welding machine as defined in claim 16 or 17 in which the biasing means is a spring, preferably a helical spring, preferably a helical spring acting in compression.

19. An internal pipe welding machine as defined in any one of claims 10-18 in which the sleeve is moved by an actuator to effect deployment and/or retraction of the positioning abutment.

20. An internal pipe welding machine as defined in any one of claims 10-19 in which during at least part of the retraction of the positioning abutment, the sleeve retracts and a retraction stop on the rod prevents the rod from retracting by contact with a welding machine retraction stop.

21. An internal pipe welding machine as defined in any one of claims 5-20 in which the rod moves within a rod guide.

22. An internal pipe welding machine as defined in claim 21 in which the rod guide includes at least one of the welding machine positioning stop and welding machine retraction stop.

23. An internal pipe welding machine as defined in any one of claims 21 or 22 in which the rod guide includes an aperture through which the rod retraction stop can pass.

24. An internal pipe welding machine as defined in claim 23 in which the positioning stop cannot pass through the aperture.

25. An internal pipe welding machine as defined in any one of claims 10-24 in which the sleeve moves within a sleeve guide.

26. An internal pipe welding machine as defined in claim 25 in which the sleeve does not rotate relative to the sleeve guide.

27. An internal pipe welding machine as defined in any one of claims 5-26 in which the positioning abutment of the rod is removable and a set of positioning abutments used for the plurality of arrester assemblies is selected from at least two sets.