GB2100640A - Improvements in or relating to rotating arc butt welding - Google Patents

Abstract

A rotating arc butt welding apparatus has its work clamping means (one 11,12, shown) and its magnetizing coil means 19,20 divided into halves moveable towards and away from the work area so that the work can be inserted between them radially. <IMAGE>

Description

SPECIFICATION Improvements in or relating to arc butt welding This invention relates to magnetically impelled arc butt welding, sometimes known as rotating arc butt welding.

In the known arc welding process tubes to be welded together are held by clamps which surround the tubes as near to their ends as possible, the tube ends being slightly spaced apart and magnetised by means of electric current in two coils which surround the tubes between the clamps and the tube ends.

The conductor turns in the coils must be insulated from each other. The insulation adds to the bulk so that the clamps have to be at some distance from the tube ends which militates against precise alignment of the tube ends. Also the coils cannot be operated at high tempertures as this would deteriorate the insulation. Ceramic insulation would be difficult and expensive.

Afurtherproblem is that the tubes must be inserted axially into the clamps and coils which can be difficult or even impossible.

According to the present invention we provide a rotating arc welding apparatus in which in place of the coils we provide a pair of conductor members movable towards and away from each other thereby moving towards and away from the work area, each member having a pair of limbs shaped to surround one side only of the work ends, and arranged so that current can flow through one pair of limbs, then through the other pair of limbs, tube clamps being provided each of which also surrounds only one side of the work area.

Preferably the conductor members are mounted on the clamps and are connected together by a flexible conductor element which allows for the movement towards and away from each other.

The invention will be further described by way of example with reference to the accompanying diagrammatic drawing which is a perspective view of a rotating are welding apparatus made in accordance with the invention.

The apparatus includes a base 10 on which tube clamping jaws 11,12 are mounted for sliding movement towards and away from each other and thus towards and away from the work area the axis of which is indicated by the broken line 5. Each jaw has a half round clamping surface so that a tube can be clamped between opposing jaws.

Another pair of clamping jaws is provided for the other tube.

The means for moving the clamping jaws may include suitable slideways and operating mechanism.

Fixed to the jaws 11,12 respectively are two electrically insulating blocks 16,17 which may be fixed by bolts or other means. Mounted respectively on these blocks 16,17 are conductor members 19,20 which are fixed to the blocks by bolts 21,22. These bolts also screw into conductors 23,24 which are connected to the source of electricity supply.

The members 19,20 are solid copper bars each bent to one side to form two or more or less upright limbs 19A, 19B, and 20A, 20B. Each limb has an upper and a lower vertical part between which is a half round part to surround one half of the work area.

Thus the two limbs of one member will surround the tube ends on one side while the two limbs of the other member surround the tube ends on the other side.

The two corresponding ends of the member 19,20, are fixed on the blocks 16 or 17 and the other ends are fixed on blocks 27,28 by bolts 30,31 which also screw into connecting tabs 32,33 on a flexible conductor 29 which has a suitable length to permit the movement towards each other and apart of the members 19,20.

Thus it will be seen that current can flow through both limbs of the member 20 through the flexible conductor 29, and through both limgs of the other member 19.

The upper ends of the members are fixed by insulating blocks 35,36 to the clamping jaws 11,12.

By means of this construction the clamping jaws are brought near to the tube ends. Also no insulation is required for the members 19,20. The members 19,20 are air insulated which allows for a higher operating temperature and rapid cooling between successive welds and for this reason the crosssectional area of the conductor bars 19,20 can be minimised.

The clamping jaws and members are movable radially of the tubes so that the tubes can be loaded and removed from the apparatus in a radial direction.

For welding 50mm diameter tubes we may use members 19,20 of 12mm x 12mm cross-section with a current of 2200 amps.

CLAIMS Filed on 25.5.82 1. A rotating arc butt welding apparatus comprising a pair of conductor members movable towards and away from each other thereby moving towards and away from the work area, each member being shaped to surround one side of the work ends, tube clamps being provided each of which operates on only one side of the work area.

2. A rotating arc butt welding apparatus as claimed in claim 1 wherein each member is in the form of a pair of limbs, each surrounding only one side of the work area.

3. A rotating arc butt welding machine as claimed in claim 1 or 2 wherein the conductor members are connected so that electric current flows serially through them.

4. A rotating arc butt welding apparatus as claimed in claim 3 wherein the conductor members are mounted on the clamps and are connected together by a flexible conductor element which allows for the movement towards and away from each other.

5. A rotating arc butt welding apparatus as claimed in any of the preceding claims wherein each of a pair of limbs has a bowed shape to surround one side of the work, the upper ends extending vertically and connected together by a bridge piece carried by a clamp, the lower ends extending horizontally, one

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to arc butt welding This invention relates to magnetically impelled arc butt welding, sometimes known as rotating arc butt welding. In the known arc welding process tubes to be welded together are held by clamps which surround the tubes as near to their ends as possible, the tube ends being slightly spaced apart and magnetised by means of electric current in two coils which surround the tubes between the clamps and the tube ends. The conductor turns in the coils must be insulated from each other. The insulation adds to the bulk so that the clamps have to be at some distance from the tube ends which militates against precise alignment of the tube ends. Also the coils cannot be operated at high tempertures as this would deteriorate the insulation. Ceramic insulation would be difficult and expensive. Afurtherproblem is that the tubes must be inserted axially into the clamps and coils which can be difficult or even impossible. According to the present invention we provide a rotating arc welding apparatus in which in place of the coils we provide a pair of conductor members movable towards and away from each other thereby moving towards and away from the work area, each member having a pair of limbs shaped to surround one side only of the work ends, and arranged so that current can flow through one pair of limbs, then through the other pair of limbs, tube clamps being provided each of which also surrounds only one side of the work area. Preferably the conductor members are mounted on the clamps and are connected together by a flexible conductor element which allows for the movement towards and away from each other. The invention will be further described by way of example with reference to the accompanying diagrammatic drawing which is a perspective view of a rotating are welding apparatus made in accordance with the invention. The apparatus includes a base 10 on which tube clamping jaws 11,12 are mounted for sliding movement towards and away from each other and thus towards and away from the work area the axis of which is indicated by the broken line 5. Each jaw has a half round clamping surface so that a tube can be clamped between opposing jaws. Another pair of clamping jaws is provided for the other tube. The means for moving the clamping jaws may include suitable slideways and operating mechanism. Fixed to the jaws 11,12 respectively are two electrically insulating blocks 16,17 which may be fixed by bolts or other means. Mounted respectively on these blocks 16,17 are conductor members 19,20 which are fixed to the blocks by bolts 21,22. These bolts also screw into conductors 23,24 which are connected to the source of electricity supply. The members 19,20 are solid copper bars each bent to one side to form two or more or less upright limbs 19A, 19B, and 20A, 20B. Each limb has an upper and a lower vertical part between which is a half round part to surround one half of the work area. Thus the two limbs of one member will surround the tube ends on one side while the two limbs of the other member surround the tube ends on the other side. The two corresponding ends of the member 19,20, are fixed on the blocks 16 or 17 and the other ends are fixed on blocks 27,28 by bolts 30,31 which also screw into connecting tabs 32,33 on a flexible conductor 29 which has a suitable length to permit the movement towards each other and apart of the members 19,20. Thus it will be seen that current can flow through both limbs of the member 20 through the flexible conductor 29, and through both limgs of the other member 19. The upper ends of the members are fixed by insulating blocks 35,36 to the clamping jaws 11,12. By means of this construction the clamping jaws are brought near to the tube ends. Also no insulation is required for the members 19,20. The members 19,20 are air insulated which allows for a higher operating temperature and rapid cooling between successive welds and for this reason the crosssectional area of the conductor bars 19,20 can be minimised. The clamping jaws and members are movable radially of the tubes so that the tubes can be loaded and removed from the apparatus in a radial direction. For welding 50mm diameter tubes we may use members 19,20 of 12mm x 12mm cross-section with a current of 2200 amps. CLAIMS Filed on 25.5.82

1. A rotating arc butt welding apparatus comprising a pair of conductor members movable towards and away from each other thereby moving towards and away from the work area, each member being shaped to surround one side of the work ends, tube clamps being provided each of which operates on only one side of the work area.

2. A rotating arc butt welding apparatus as claimed in claim 1 wherein each member is in the form of a pair of limbs, each surrounding only one side of the work area.

3. A rotating arc butt welding machine as claimed in claim 1 or 2 wherein the conductor members are connected so that electric current flows serially through them.

4. A rotating arc butt welding apparatus as claimed in claim 3 wherein the conductor members are mounted on the clamps and are connected together by a flexible conductor element which allows for the movement towards and away from each other.

5. A rotating arc butt welding apparatus as claimed in any of the preceding claims wherein each of a pair of limbs has a bowed shape to surround one side of the work, the upper ends extending vertically and connected together by a bridge piece carried by a clamp, the lower ends extending horizontally, one end being connected to a terminal block and the other end being connected to one end of the flexible conductor.

6. A rotating arc butt welding apparatus substantially as discribed with reference to and as shown in the accompanying drawings.