METHOD AND APPARATUS FOR CONDUCTING CURRENT TO AN ELECTRODE IN ARC WELDING, ARC CUTTING OR THE LIKE OPERATIONS

Abstract: The objective of this invention is to provide a method of conducting electricity in an arc welding device especially to an arc electrode (1), such as a welding, cutting, cleaning or electrolyte coating electrode, or to a device supporting such electrode, as well as an arc welding device to realize the method. Characteristic to the method acording to the invention is that the electrode (1) or the device supporting it is brought to a direct contact before the arc area with a flowing, preferable liquid, medium in contact with the power supply. The arc welding device according to the invention is characterized in that the devices for conducting electric current comprises a chamber (2) adapted inside the casing (6) of the device and including flowing, preferably liquid, medium, which is in electrically conductive contact to the power supply and the electrode (1) or the device supporting it.

Description: Method and apparatus for conducting current to an electrode . in arc welding, arc cutting or the like operations. 5 This invention relates to the process and method of conducting electricity in equipment and devices for arc welding, cutting or similar operations and also to an arc welding device to carry out the method.. The par¬ ticular object of the invention is a method of direct- 10 ing the electric current in this type of equipment to the arc electrode, . hereafter generally referred to as ' " - ■ the end part, or equipment, as the rotating drive shaft or sleeve, to which the end part is fixed. 15 Traditionally the electric current is conducted to f.ex. the welding electrodes or drive shaft in the arc weld¬ ing device by mechanical contact members to be pressed in contact with welding electrode or shaft and connec¬ ted with electric conductors, such as spring loaded 20 clamp cheeks or carbon brushes, which wear out in the use. Underwater welding and arc cutting have been in the recent years an object of growing interest and deve- 25 lopment work. Repairs and servicing of drilling plat¬ forms, underwater gas and oil pipes, ships and docks are the processes in which underwater welding has most- ly.been used. The objects are in these cases generally such, that their lifting to the water surface is im- 30 possible or very costly.. The objective of underwater welding, as well as in welding generally, is always the achievement of the highest quality welds.. Then it is of vital importance that the conduction of elec¬ tricity to the end part of the arc welding device to 35 be targeted towards the worksite will be even and un¬ interrupted and that the changing of the end part electrode should be' easy and swift even if the size is being changed. Previously recognizable problems with welding and cut¬ ting methods and equipment particularly connected with the conduction of necessary electricity have been for instance the reliability of mechanical contacts. In ad- dition to strength related failures, the contamination has produced contact disturbances resulting in welding faults or the welding or cutting process might comple¬ tely be disrupted or interrupted. Another drawback is, that the adjustment possibility of contact members for end parts with different sizes and shapes is rather limited. The objective of the present invention is to eliminate the above-mentioned drawbacks and limitations to arc welding processes and equipment already known in the art and to achieve a method for electrical conducting, to which the invention particularly is connected, which is more reliable and simple and guarantees the use of the welding device or more generally the arc welding device in all welding applications. It would also enab¬ le the use of the arc welding device in a more conve¬ nient and flexible way in the remote-controlled subma¬ rine use of robots, which significantly reduces both the costs and the risks connected to the- underwater operations. This objective has been achieved with the method and arc welding devices according to the invention the characteristic features of which are presented in the appended claims. The primary feature of this invention is that no moving parts are necessary for the conducting of electricity and so the device according to the invention is very reliable, simple and easily adaptable to different ob¬ jects of use, and that by using the solution of the in¬ vention the electric current can very easily be conduct¬ ed also to rotating welding, cutting, cleaning and/or coating electrodes. This means that this method can suc¬ cessfully be utilized in all arc welding applications. An especially beneficial feature of the electrical con¬ ducting according to the invention is the production of an even magnetic field which, particularly in welding applications, results in an even arc. The method and arc welding device according to the in¬ vention are described in the following by some preferab¬ le applications with reference to the accompanying drawings, in which - Fig. 1 shows a cross section of a continuous feeding welding equipment, - Fig. 2 shows a cross section of an arc welding device with a rotatable drive shaft to be provided with an end part for welding, cutting, cleaning and/or electrolyti- cal coating, and - Fig. 3 shows an arc welding device especially adapted for rod welding. According to the primary feature of the invention for the conduction of electricity to the electrodes (1) which hereafter- are referred to as the end part, or to devices (3, 4) to which the end part is designed to be connected, for various applications such- as- arc welding, cutting, cleaning or electrolytical coating, the end part 1 or device 3 or 4 to which the end part 1 will be connected is brought before the arc area to the electrically conducting contact with a flowing, pre¬ ferably liquid, medium, as for instance mercury. In this advantageous application the above-mentioned objective is realized by placing the drive shaft 3 to extend or by guiding the welding electrode (1) to penetrate through the chamber 2. full of. medium or by adapting the sleeve part 4 to extend to the chamber 2 at least partially filled with the medium, so that the electrical current is conducted from the medium to the end part 1 either directly or indirectly through the drive shaft 3 or sleeve part 4 or locking arrangements possibly placed in them. For the arc to be ignited the flowing medium in the chamber 2 is electrically connected to one of the power supply terminals, f.ex. the "+"-terminal, and the basic material in the worksite correspondingly to the other power supply, say "-"-terminal. According to one advan¬ tageous embodiment of the invention the medium is flowed between the power supply and the chamber 2, so that the flowing medium drives the equipment 5 drawing the welding wire 1. It must, however, be ,noticed that flowing of the medium is not necessary for the opera¬ tion of the invention, but that the chamber 2 can- also be made as a closed space and the medium in it can be connected also by electrical conductors to the power supply. In this case the electric current needed for the drawing equipment 5 of the welding wire.1. can be taken from the medium through the electrical transfor- mator. In the continuously fed arc felder application of the Figure.1 , in which the conduction method of the electric current to the welding wire 1 according to the invention has been realized, the reference number 6 means the casing of the welding device, inside which has been formed a chamber 2 containing the medium as described above. The chamber 2 itself is for the elimination of current losses produced advantageously from a material with electrically insulating properties, whereby the use of the welding device is also secured. As shown in Fig. 1 the chamber 2 in this exemplary case includes the inlet 21 and outlet 22 for the welding wire 1. Both of the said openings are sealed against the outflow of the medium and in the underwater operations inflow of water. To the outlet 22 has been directly con¬ nected the mouthpiece 7 of the welding device project¬ ing in curved form from the other end of the body part in order to support and guide the path of the welding wire 1 to the welding object. Inside the chamber 2 has also been mounted in bearings a pair of rollers 24, 25 functioning .as the drawing de¬ vice 5 for the welding wire and rotating in opposite di¬ rections, so that they draw the welding wire 1 conti- nuously from the inlet 21 towards the outlet 22. As stated before the operation of the pair of rollers 24, 25 can be carried out f.ex. by a hydraulically flowing medium or electric current taken from the medium through an electrical transformator. In both cases it is possible to arrange the rotational speed of the rol¬ lers as steplessly adjustable for instance b a trigger adapted to the body part, which trigger in the hydrau¬ lic use affects to the circulating device 26 of the me- dium for the adjustment of flow rate or quantity and in the electrical use to the resistance in the electric¬ al transformator to change the magnitude of the electric current operating the pair of rollers'. For the hydraulic use the chamber 2 comprises the inlet 27 and the outlet 28 for the medium. As described before the flow openings 27 and 28 are connected to each other by the medium flow channel 29, in which has been mounted a circulating device 26, e.g. a suitable liquid pump. According to one advantageous application of the. inven¬ tion the inlet 21 and the outlet 22 can be connected together by a tubular contact organ made of electrically conductive material, which during the welding process is pressed against the welding wire to conduct the welding current.- The advantage in this particular app¬ lication is that the chamber 2 can be made absolutely tight and that the welding wire 1 is supported all the time along the whole length of the welding device, and also that the tubular contact organ facilitates the adaptation of the welding wire 1 through the chamber 2. To make the entrance of the welding wire easier also a conically' towards the outlet 22 tapering guide sleeve can be placed in the chamber. In Fig. 2 has been shown an arc welding device accord¬ ing to another application of the invention, namely the arc welding device provided with a rotating axle 3. To the sleeve part 4 at the end of the axle is to be connected and possibly locked by suitable, for instance clamp-like locking means the arc welding,, cutting, cleaning and/or electrolytically coating end part to rotate along with the axle. In the exemplary case of Fig. 2 the electric current is fed to the mentioned end part through the axle 3. To achieve this in the casing 6 of the device has been formed a chamber 2, which is filled or to which is fed or in which is circulated continuously electri¬ cally conductive advantageously liquid medium, such as mercury. The medium is electrically connected to the power supply and it is in continuous contact with the outer perimeter of the axle 3. To eliminate the current losses the chamber 2 itself has been made of electrical¬ ly insulating material and between the axle 3 and the rotating device has been adapted a spacer 31 of elec¬ trically insulating material, whereby the electric cur¬ rent is introduced through the axle 3 and the sleeve part 4 to the end part. To make the underwater use of the device as sure as possible the chamber 2 as well as the clearance between the casing 6 and the axle 3 has been sealed against leakages directed inwards as well as outwards. In the Sealing for instance spring-loaded slip ring gaskets or lip gaskets can be used depending. on the applica¬ tion and the loads applied to the sealings. In deeper work conditions the use of the slip ring gaskets be- comes necessary. In Fig. 3 has been shown an arc welding device accord¬ ing to a third advantageous application of the inven¬ tion and intended especially for rod welding. Electri- city is. conducted to the end part.1, which in this case is a welding rod, through the sleeve part 4 in the ca¬ sing 6 of the device. The other end of the welding rod has been inserted into the sleeve part 4, the other end of which extends partially to the chamber 2 inside the casing 6, in which chamber there is or into which it is fed or in which continuously is circulated flowing, pre¬ ferably liquid medium, such as mercury. The chamber 2 itself is also in this exemplary case made of electri- cally insulating material and the medium has been elec¬ trically connected to the . either terminal of the power supply. The invention has been described above only by some of its advantageous applications. This, of course, does not limit its sphere, but the invention can be varied in its details even significantly in the scope of the appen¬ ded claims.

Claims: CLAIMS 1. A method of conducting electric current in an arc welding device to the arc electrode (1), for instance to the end part for welding, cutting, cleaning and electrolytical coating, or to a device (3, 4) support¬ ing the arc electrode, c h a r a c t e r i z e d. in that the electrode (1) or the device (3, 4) supporting it is before the arc area brought to contact with flowing, preferably liquid, electrically conductive medium, which is connected to the power supply. 2. A method according to the claim 1, c h a r a c ¬ t e r i z e d in that mercury is used as the medium. 3. A method according to the claim 2, c h a r a c - t e r i z e d in that mercury is circulated between the mercury chamber (2) in the device and the power supply. 4. Arc welding device comprising a casing (6) and equipment adapted inside it to conduct electricity to the arc electrode (1), such as e.g. welding, cutting, cleaning or electrolyte coating end part, or to the device (3, 4) supporting the arc electrode, c h a r a c t e r i z e d in that the equipment (2) for conducting electric current comprises a chamber adapted inside the casing (6) and including flowing, preferably liquid, electrically conductive medium, which is in electrically conductive contact to the power supply and the arc electrode (1) or the device (3, 4) supporting it. 5. Arc welding device according to the claim 4, c h a r a c t e r i z e d in that the arc electrode is a continuously fed welding or. cutting wire .(1) , c h a r a c t e r i z e d in that the chamber (2) comprises: - entrance inlet (21) and outlet (22) for the wire (1), - drawing devices (5) for continuous drawing of the wire from the inlet (21) inside the chamber (2) and for guiding the wire from the outlet (22) through the mouthpiece ' (7) fixed to the end of the casing (6) towards the worksite, and - at least one medium inflow opening (27), to which is connected the medium flow channel (29) adapted between the chamber (2) and the power supply» 6. Arc welding device according to the claim 5, c h a r a c t e r i z e d in that the chamber (2) comprises also the medium outlet (28) , and that in- and outflow openings (27 and 28) have been connected together by a medium circulating channel (29) passing through the power supply and provided with a medium circulating device (26) . 7. Arc welding device according to the claim 6, c h a r a c t e r i z e d in that the drawing devices (5) consist of at least one pair of rollers or rolls (24, 25) receiving their drive from the hydraulic pres¬ sure of the flowing medium. 8. Arc welding device according to the claim 5, c h a r a c t e r i z e d in that the drawing devices (5) receive their drive from the electrically conductive medium by the electric current transformator. 9. Arc welding device according to the claim 4, in that the device supporting the arc electrode is a drive axle (3) rotating the arc electrode, c h a r a c t e r i z e d in that this dri¬ ve axle (3) has been adapted to extend through the cham¬ ber (2) formed inside the casing (6) , so that the medium is in direct electrically conductive contact with the outer perimeter of the axle (3) . 10. Arc welding device according to the claim 4, in which the device supporting the arc electrode is a sleeve part (4) to which the electrode is to be connec¬ ted, c h a r a c t e r i z e d in that the sleeve part (4) has been adapted to extend at least partially into the chamber (2) formed inside the casing (6) , so that the medium is in direct electrically conductive contact with the outer surface of the sleeve part (4) .

Inventors: NIINIVAARA JUHANI ENSI KYOESTI, NIINIVAARA, JUHANI, ENSI, KYOESTI
Applicants: NIINIVAARA OY
Application year: 1986
Main classification: B23K9
IPC codes: B23K9, H01R41, H05B7