GB1582893A

GB1582893A - Seal welding torches

Info

Publication number: GB1582893A
Application number: GB2010076A
Authority: GB
Original assignee: Foster Wheeler (London) Ltd
Current assignee: Foster Wheeler (London) Ltd
Priority date: 1977-05-13
Filing date: 1977-05-13
Publication date: 1981-01-14

Description

(54) SEAL WELDING TORCHES (71) We, FOSTER WHEELER POW ER 'PRODUCTS LIMITED, a British Company, of Greater London House, Hampstead Road, London NW1 7QN, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to seal welding torches.

The present invention provides a seal welding torch comprising a hollow cylindrical support on which a welding head is rotatably mounted, the hollow cylindrical support is arranged to accept . a locating means for aligning the support with an item to be welded, and the welding head is capable of being moved radially relative to the support out from and into a welding position.

The welding head can have a nonconsumable electrode and may be provided with a feed for supplying welding filler wire to the region of the weld. In use, a circular seal weld is made by rotating a sleeve about the central support, the sleeve orbiting the welding head around the weld region.

The welding head can be carried by means- which enable it to be moved both parallel to the axis of rotation and transverse to the axis of rotation so that the welding head can be accurately aligned and positioned for making the seal weld. In addition, the welding head may be mounted so that the orientation of the nonconsumable 'electrode relative the axis of rotation, and therefore the axis of the weld, can be varied.

A seal welding torch according to the invention will now be described, by way of example, with reference to the drawings accompanying the Complete specification in which: Figure 1 is a side elevation of one embodi ment of a torch according to the invention; Figure 2 is a transverse section through the torch of Figure 1; and Figure 3 is a section taken along the B-B of Figure 2.

The welding torch 10 shown in the draw ings includes a hollow cylindrical support 12 about which a sleeve 14 is rotatably mounted on the support through thrust bearings 16, needle bearings 18 and 20 and a ball bearing race 22. The end 24 of the support 12 is threaded and lock nuts 26 hold the sleeve 14 in place, the bearings 18 and 20 being held apart by a spacer 27. The support tube 12 has a hollow cylindrical bore 28.

The welding head generally indicated at 30 is supported by the sleeve 14 through an arm 32 whose end terminates in a cross-slide 34. The cross-slide 34 is, in turn, carried by another cross-slide 36 whose direction of sliding is transverse to that of the cross-slide 34 and the cross-slide 36 is in turn joined to the sleeve 14. The movement of the cross -slide 34 is controlled by means of a motor/ gear box assembly 40. This assembly drives a threaded shaft 42 which screws into a portion 44 of the arm 32.

In turn the movement of the slide 36 is controlled by a motor 46 driving a threaded shaft 48 by means of a worm and worm wheel assembly 49. Engaged on the threaded shaft 48 is a bush 50 which is in turn joined to the slide 34. As will be appreciated one can by operation of the motors 40 and 46 cause relative movement of the slides 34 and 36 so causing the head to be moved parallel to the axis df rotation 52 and transverse to that axis, respectively.

The welding head 30 includes a non consumable electrode 54 surrounded by a ceramic shield 56 through which inert shielding gas may be supplied to the weld region. The electrode and shield are sup ported by a body 58 which is rotatably 'journalled in the end of the arm 32. A worm wheel 60 is, (see Figure 1), joined to the body 58, in engagement with a worm 62 driven by means of a motor 64. Rotation of the motor therfore enables the orientation of the welding head 30 relative to the axis 52 to be altered.

In order to insulate the welding electrode 54 from the remainder of the welding torch the arm includes an insulated portion 66 (Figure 3) and the drive from the motor 64 to the worm 62 includes an insulated coupling 68.

Also mounted on the sleeve 14 is a drive assembly 70 for supplying welding filler wire. This includes a drive motor/gear box assembly 72 driving knurled drive rollers 74 and 76 through a gear 78. Again the motor 72 is insulated from the welding filler wire by means of an insulating coupling 80. The welding filler wire is withdrawn from a reel 82 through a guide 84 by the rollers 74 and 76 and supplied through another guide 86 and sleeve not shown to the region of the weld.

The stationary support 12 is fixed to a flanged sleeve 90. It is also joined by pins to a wheel gear 92, meshing with a pinion gear 94 driven by a motor gear box arrangement 96, the latter being fixed to the sleeve 14.

Operation of the motor 96 therefore causes the sleeve 14 and the welding head 30 which it carries to orbit about the axis 52 during the making of the weld.

The torch is fixed to a suitable support by means of the flange of the flanged sleeve 90 and this support could be moveable so as to allow the welding head to be aligned with a particular item 98 to be welded. It is vital that the axis of rotation 52 accurately aligns with the axis of the item 98 to be welded so as to ensure a good circular seal weld. The hollow cylindrical bore through the support tube 12 enables one to do this by inserting for example a locating pin through the bore of the support 12 to engage a central depression in the item to be welded. The position of the flanged sleeve 90 can then be accurately fixed, the locating pin removed and thereafter the torch is ready to be set up for welding. It may well be necessary to move the slide 36 to retract the welding head 30 during the positioning of the locating pin but once the pin is removed the welding head can be restored to position and a seal weld made in conventional manner.

Besides being used to position the welding head accurately along the axis of rotation, the slide 34 and its associated motor 40 can be used in conventional manner to control the length of the arc by monitoring the voltage drop across the arc continuously and controlling the operation of the motor 40 to maintain the arc at the desired substantially constant value.

WHAT WE CLAIM IS: 1. A seal welding torch comprising a hollow cylindrical support on which a welding head is rotatably mounted, the hollow cylindrical support is arranged to accept a locating means for aligning the support with an item to be welded, and the welding head is capable of being moved radially relative to the support out from and into a welding position.

2. A torch as claimed in Claim 1 in which the head is rotatably mounted on the support by way of a sleeve.

3. A torch according to claim 1 or 2, in which the welding head can be moved both transversely of and parallel to the axis of the support.

4. A torch according to claim 3, comprising a motor for moving the welding head transversely of the axis of rotation of the sleeve and a separate motor for moving the welding head parallel to axis of rotation, of the sleeve.

5. A torch according to any of the preceding claims in which the orientation of the welding head relative to the axis of the support can be altered.

6. A torch according to claim 2, in which the sleeve is rotatable about the support by means of a motor fixed to the sleeve, and having a gear wheel which engages with a gear wheel non-rotatably fixed to the support.

7. A torch according to any of the preceding claims having a non-consumable electrode and means for supplying welding filler wire to the region of the electrode tip.

8. A torch according to claim 6,in which the means for supplying the welding filler wire to the region of the electrode tip comprises a motor gear box assembly in driving communication with knurled drive rollers.

9. A torch according to any of the preceding claims, in which the electrode is surrounded by a ceramic shield through which inert gas can be supplied to the 10. A seal welding torch substantially as herein described with reference to the accompanying drawings.

11. A method of aligning a seal welding torch of the type claimed in any of the preceding claims with an item to be welded which method comprises aligning the sup

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. wheel 60 is, (see Figure 1), joined to the body 58, in engagement with a worm 62 driven by means of a motor 64. Rotation of the motor therfore enables the orientation of the welding head 30 relative to the axis 52 to be altered. In order to insulate the welding electrode 54 from the remainder of the welding torch the arm includes an insulated portion 66 (Figure 3) and the drive from the motor 64 to the worm 62 includes an insulated coupling 68. Also mounted on the sleeve 14 is a drive assembly 70 for supplying welding filler wire. This includes a drive motor/gear box assembly 72 driving knurled drive rollers 74 and 76 through a gear 78. Again the motor 72 is insulated from the welding filler wire by means of an insulating coupling 80. The welding filler wire is withdrawn from a reel 82 through a guide 84 by the rollers 74 and 76 and supplied through another guide 86 and sleeve not shown to the region of the weld. The stationary support 12 is fixed to a flanged sleeve 90. It is also joined by pins to a wheel gear 92, meshing with a pinion gear 94 driven by a motor gear box arrangement 96, the latter being fixed to the sleeve 14. Operation of the motor 96 therefore causes the sleeve 14 and the welding head 30 which it carries to orbit about the axis 52 during the making of the weld. The torch is fixed to a suitable support by means of the flange of the flanged sleeve 90 and this support could be moveable so as to allow the welding head to be aligned with a particular item 98 to be welded. It is vital that the axis of rotation 52 accurately aligns with the axis of the item 98 to be welded so as to ensure a good circular seal weld. The hollow cylindrical bore through the support tube 12 enables one to do this by inserting for example a locating pin through the bore of the support 12 to engage a central depression in the item to be welded. The position of the flanged sleeve 90 can then be accurately fixed, the locating pin removed and thereafter the torch is ready to be set up for welding. It may well be necessary to move the slide 36 to retract the welding head 30 during the positioning of the locating pin but once the pin is removed the welding head can be restored to position and a seal weld made in conventional manner. Besides being used to position the welding head accurately along the axis of rotation, the slide 34 and its associated motor 40 can be used in conventional manner to control the length of the arc by monitoring the voltage drop across the arc continuously and controlling the operation of the motor 40 to maintain the arc at the desired substantially constant value. WHAT WE CLAIM IS:

1. A seal welding torch comprising a hollow cylindrical support on which a welding head is rotatably mounted, the hollow cylindrical support is arranged to accept a locating means for aligning the support with an item to be welded, and the welding head is capable of being moved radially relative to the support out from and into a welding position.

9. A torch according to any of the preceding claims, in which the electrode is surrounded by a ceramic shield through which inert gas can be supplied to the

10. A seal welding torch substantially as herein described with reference to the accompanying drawings.

port with the item to be welded with the aid of an aligning means and moving the welding head radially relative to the support into a welding position.