GB2218309A - Welding apparatus - Google Patents

Abstract

A machine for welding, and in particular TIG welding. comprises a magazine carrying a plurality of electrodes and apparatus to facilitate the movement of these electrodes to the welding position. In one preferred example the magazine 1 is in the form of a circular disc 2, with a plurality of electrodes 3 in a planar radial array in the disc. The magazine 1 is mounted such that it can be rotated about the drive shaft 8 by a stepper motor 7 in order that a worn electrode presented at the workpiece will be replaced with a new one. The whole apparatus is rotatable about its axis 11 by the action of the stepper motor 12. In the embodiment of Fig 3 the electrodes 22 are carried by a non-conducting belt whose ends are wound on spools 23, 25. <IMAGE>

Description

WELDING APPARATUS This invention relates to welding apparatus, and in particular to TIG welding apparatus.

The method of TIG welding and apparatus used therefor is well known.

A difficulty which arises with TIG welding is that it is generally necessary to change the electrode at regular intervals due to burn-down thereof during welding, this making TIG welding generally unsuitable for continuous use in large scale manufacturing operations where equipment being used would have to be shut down to effect an electrode change.

According to this invention there is provided TIG welding apparatus including a magazine carrying a plurality of electrodes, the magazine being movable relative to the position of welding thereby to present each of the electrodes carried thereby in turn for use at the welding position.

This invention will now be described by way of example with reference to the drawings, in which: Figure 1 is a diagrammatic side view of a TIG welding apparatus according to the invention; Figure 2 is a diagrammatic side elevational view of the electrode magazine of the apparatus of Figure 1; and Figure 3 is a diagrammatic side view of another TIG welding apparatus according to the invention.

The apparatus shown in Figures 1 and 2 includes a magazine 1 in the form of a circular disc 2 of electrically conductive material such as copper, and carrying a plurality of tungsten welding electrodes 3 arranged in a planar radial array in respective inert gas feed passages 4 in the disc 2. Each electrode 3 is longitudinally movable radially of the disc 2 and has an associated screw 5 by which it can be secured against such movement.

Each of the gas feed passages terminates in a lens member 6 of ceramic material serving to direct gas flowing from the associated passage 4 in the required direction.

The magazine 1 is mounted for rotation relative to a workpiece 100 to be welded about the central axis of the disc 2 perpendicular to the plane of the array of electrodes 3. The rotary movement of the magazine 1 is effected by means of an electrical stepper motor 7 which is coupled to the magazine 1 by means of a drive shaft 8. The gas feed passages 4 in the disc 2 are supplied, in use, from a cordon source 9, the gas passing to the magazine 1 along a groove 10 extending parallel to the drive shaft 8, the arrangement being such that only the passage 4 associated with the electrode 3 being used at any instant is supplied with gas at that instant.

The magazine 1, stepper motor 7 and drive shaft 8 are mounted for rotation as a unit about an axis 11 parallel to the plane of the array of electrodes 3 carried by the disc 2, by means of a further motor 12. The gas is supplied from the source 9 to the groove 10 by way of a passage 13 extending along the axis 11, the source 9 being coupled to the passage 13 by means of a rotary coupling arrangement 14.

It will be appreciated that if welding is to take place in an inert environment then the gas feed arrangements described above can be omitted, the magazine 1 simple carrying the plurality of electrodes 3.

During use a single one of the electrodes 3 will be presented to the workpiece 100 and welding will take place in known manner for either a set period of time or a set number of welds, or until a control system senses a variation in the welding voltage or current. At such time the stepper motor 7 will be operated to index the magazine 1 to present a new electrode 3 to the workpiece 100. Welding will continue in this manner until all of the electrodes 3 have been used, when the magazine 1 will be replaced with a new one carrying a plurality of new electrodes. The motor 12 can be operated to move the motor 7, drive shaft 8 and magazine 1 such that a plurality of workpieces 100 arranged in a circle about the axis 11 can be welded as required.

Referring now to Figure 3, the apparatus here shown includes a magazine 20 in the form of an electrically non-conductive belt 21 carrying a plurality of longitudinally spaced tungsten welding electrodes 22 extending from one side of the belt but each having a head portion accessible at the opposite side of the belt 21. The belt 21 is wound on a first spool 23 in a housing 24 from which it can be unwound to be rewound on a second spool 25 in a housing 26, the housings 25 and 26 possibly being integrally formed whereby the belt 21 and housings 25 and 26 together form a cassette type of arrangement which can be removed from the apparatus and replaced by a similar arrangement.

The belt 21 is arranged to be wound under a welding head 27 having means to contact any electrode 22 carried by the belt 21 which is located at the head 27. The head 27 also incorporates the necessary gas feed arrangement which, as with the apparatus of Figures 1 and 2, can be omitted if welding is to take place in an inert environment.

When any particular electrode 22 on the belt 21 has been consumed, then the belt 21 is simply wound on from the spool 23 to the spool 25 until the next electrode 22 on the belt 21 is located as necessary at the head 27.

Apparatus as described above has the advantage that it can be operated to give substantially continuous welding for a prolonged period of time without the need for frequent lengthy stops for electrode changes.

Claims (13)

1. TIG welding apparatus including a magazine carrying a plurality of electrodes, the magazine being movable relative to the position of welding thereby to present each of the electrodes carried thereby in turn for use at the welding position.

2. Apparatus as claimed in Claim 1, in which the magazine is circular and carries the electrodes arranged in a planar radial array, the magazine being mounted for rotation relative to the position of welding, about the central axis perpendicular to the plane of the electrode array.

3. Apparatus as claimed in Claim 2, in which each electrode is longitudinally movable radially of the magazine, and including means to secure each electrode against such movement.

4. Apparatus as claimed in Claim 2 or Claim 3, in which each electrode is mounted in a respective gas feed passage through which gas is supplied to the position of welding during use of the electrode.

5. Apparatus as claimed in Claim 4, in which each gas feed passage terminates in a lens member serving to direct the gas flow at the position of welding.

6. Apparatus as claimed in Claim 4 or Claim 5, in which the gas feed passages are supplied from a common supply, only that associated with the electrode being used at any instant being supplied at that instant.

7. Apparatus as claimed in any preceding claim, in which movement of the magazine is effected by means of a stepper motor.

8. Apparatus as claimed in Claim 7 as dependent upon Claim 2, in which the magazine is coupled to the stepper motor by means of a drive shaft, the gas supply extending by way of a groove parallel to the drive shaft.

9. Apparatus as claimed in any one of Claims 2 to 8, in which the magazine, stepper motor and drive shaft are mounted for rotation as a unit about an axis parallel to the plane of the electrode array in the magazine.

10. Apparatus as claimed in Claim 1, in which the magazine comprises an electrically non-conductive belt carrying a plurality of longitudinally spaced electrodes extending from one side of the belt but accessible at the opposite side of the belt.

11. Apparatus as claimed in Claim 10, in which the belt is wound on a first spool from which it can be unwound to be rewound on a second spool.

12. Apparatus as claimed in Claim 11, in which the belt and first and second spools are parts of a cassette arrangement.

13. TIG welding apparatus substantially as hereinbefore described with reference to Figures 1 and 2 or Figure 3 of the drawings.