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Title:
ARC WELDING TORCH
Document Type and Number:
WIPO Patent Application WO/2021/064470
Kind Code:
A2
Abstract:
In the case an arc welding torch device, having a consumable electrode, wherein the electrode is provided with a direction of movement from a rear end of the arc welding torch device for feeding in the direction of a front end of the arc welding torch device, in the region of which the electrode is consumed during an arc welding process, the electrode in the arc welding torch device is guided in an exchangeable wire core, the wire core being arranged at least in the region of the rear end of the arc welding torch device in a guide element surrounding the wire core and designed as an exchangeable wear part, and the guide element of the wire core being provided for the joint exchange of the wire core due to wear, in order to create a possibility of better checking and assessing the correct assembly of an exchanged wire core, it is proposed that a predetermined end position in the arc welding torch device is provided for the guide element with respect to its insertion direction into the arc welding torch device, and when the end position is attained by the guide element, a position signaling means is perceptible outside the arc welding torch device.

Inventors:
KLEIN, Thomas (Rodenbach, DE)
Application Number:
IB2020/001071
Publication Date:
April 08, 2021
Filing Date:
December 02, 2020
Export Citation:
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Assignee:
SKS WELDING SYSTEMS GMBH (Kaiserslautern, DE)
SKS WELDING SYSTEMS INC. (Rochester Hills, Michigan, US)
International Classes:
B64C39/02
Attorney, Agent or Firm:
HARRIS, Christopher, P. (Sundheim Covell & Tummino, LLP,1300 East Ninth Street,Suite 170, Cleveland Ohio, US)
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Claims:
Claims

1. The invention relates to an arc welding torch device, having a consumable electrode, the electrode being provided with a direction of movement from a rear end of the arc welding torch device for feeding in the direction of a front end of the arc welding torch device, in the region of which the electrode is consumed during an arc welding process, the electrode in the arc welding torch device is guided in an exchangeable wire core, the wire core being arranged at least in the region of the rear end of the arc welding torch device arranged in a guide element which surrounds the wire core and is designed as an exchangeable wear part, the guide element of the wire core being provided for joint wear-related replacement of the wire core, characterized in that a predetermined end position is provided in the arc welding torch device for the guide element with regard to its direction of insertion into the arc welding torch device, and when the guide element reaches the end position, a position signaling means can be perceived outside of the arc welding torch device.

2. Arc welding torch device according to claim 1 , characterized in that when the end position is reached by the guide element, a position indicating means arranged outside the arc welding torch device can be visually perceived.

3. Arc welding torch device according to claim 1 or 2, characterized in that the visual position indicating means is part of the guide element.

4. Arc welding torch device according to one of the preceding claims, characterized in that the guide element is guided with one of its ends through an outer, end-side housing part of the arc welding torch device, in particular through an end cap, and protrudes outward from its housing from the outer housing part of the arc welding torch device.

5. Arc welding torch device according to one of the preceding claims, characterized in that the guide element is designed as a sleeve with - in relation to its longitudinal extent along its longitudinal axis - different outer diameters.

6. Arc welding torch device according to claim 5, characterized in that the guide element for the wire core has two sections of the outer jacket surface, each with a constant diameter, between which a section with a conical shape of the jacket surface is arranged.

7. Arc welding torch device according to one of the preceding claims, characterized in that the end of the guide element is only passed through the outer housing part, in particular through the end cap, and is arranged on the outer housing part without connection.

8. Arc welding torch device according to one of the preceding claims, characterized in that the guide element for the wire core is arranged with its larger outer diameter in a sleeve-shaped inlet body and without connection to the latter.

9. Arc welding torch device according to one of the preceding claims, characterized in that the sleeve-shaped inlet body is detachably fastened with its outer jacket surface to the housing of the arc welding torch device, in particular to the outer end-side housing part.

10. Arc welding torch device according to one of the preceding claims, characterized in that the outer end-side housing part is detachably arranged on the jacket tube of the arc welding torch device.

11. Arc welding torch device according to one of the preceding claims, characterized in that a sealing element is arranged between the outer end-side housing part and the guide element for the wire core.

12. Arc welding torch device according to one of the preceding claims, characterized in that a second seal is arranged between the sleeve-shaped inlet body and the housing of the arc welding torch device.

13. Exchangeable assembly for an arc welding torch device as well as a housing-side end cap of the arc welding torch device, the exchangeable assembly having a wire core provided for arrangement inside the arc welding torch device and a guide element arranged in the region of one end of the wire core and surrounding the latter, characterized by a component on which the guide element is formed and by a section with a smaller outer diameter, preferably a constant smaller diameter, an adjoining section with a conical outer section, and a section adjoining the conical section with a larger outer diameter.

14. Exchangeable assembly according to claim 13, characterized in that the component with the guide element is provided with an end portion of its outer surface which is matched to the through hole of the end cap in such a way that in the position of use of the guide element its end portion protrudes from the through hole of the end cap.

15. Exchangeable assembly according to claim 14, characterized in that the guide element rests in its position of use against an inner surface of the end cap or against an inner surface of another component of the housing of the arc welding torch device, whereby an insertion movement of the exchangeable assembly is limited, and here the end portion of the guide element protrudes from the end cap and thus from the arc welding torch.

16. Arc welding torch device with a consumable electrode, wherein the electrode is provided with a direction of movement from a rear end of the arc welding torch device for feeding in the direction of a front end of the arc welding torch device, in the region of which the electrode is consumed during an arc welding process, the electrode in the arc welding torch device is guided in an exchangeable wire core, the wire core being in turn arranged at least in the region of the rear end of the arc welding torch device in a guide element which surrounds the wire core and is designed as a replaceable wear part, the guide element of the wire core being provided for joint wear-related replacement of the wire core, characterized by a kink protection means for the welding wire protruding from the arc welding torch device and arranged between the outer end cap of the arc welding torch device and wire feeding means, in which kink protection means the welding wire is guided.

17. Arc welding torch device according to claim 16, characterized in that the kink protection means is detachably arranged in the arc welding torch device and a section of the kink protection means protrudes from a recess in the end cap of the arc welding torch device.

18. Arc welding torch device according to claim 16 or 17, characterized in that the kink protection means is sleeve-shaped and has a continuous recess for receiving the welding wire, and preferably in the wire-feed-side end a boundary wall of the continuous recess is provided with a bevel.

19. Arc welding torch device according to at least one of the preceding claims 16 to

18, characterized in that the kink protection means is formed in one piece with a receptacle for a wire core arranged within the arc welding torch device.

20. Arc welding torch device according to at least one of the preceding claims 16 to

19, characterized in that the kink protection means is arranged without connection on the arc welding torch device.

21. Arc welding torch device according to at least one of the preceding claims 16 to

20, characterized in that the kink protection means is arranged in a predetermined position in the arc welding torch device due to a positive-fitting arrangement of the kink protection means in the axial direction in the arc welding torch device.

22. Arc welding torch device having a consumable electrode, wherein the electrode is provided with a direction of movement from a rear end of the arc welding torch device for feeding in the direction of a front end of the arc welding torch device, in the region of which the electrode is consumed during an arc welding process, the electrode in the arc welding torch device is guided in an exchangeable wire core, the wire core being arranged at least in the region of the rear end of the arc welding torch device in a guide element surrounding the wire core and designed as an exchangeable wear part, the guide element of the wire core being provided for the joint exchange of the wire core due to wear, in particular according to one of the preceding claims, characterized in that in the region of a wire-feed-side end of the arc welding torch device only the guide element designed in one piece is in contact with the wire core.

23. Arc welding torch device according to one of the preceding claims, characterized in that the guide element, at least one contact area of the guide element with the wire core, preferably the entire one-piece guide element, has an electrically non- conductive material.

24. Arc welding torch device according to one of the preceding claims, characterized by several guide elements which can be inserted into the arc welding torch device alternately and in exchange for one another and which have different materials, in particular ceramic or plastic materials.

25. Arc welding torch device according to at least one of the preceding claims, which is provided for arrangement on a welding robot which has a robot arm on which a connection device is provided which is rotatable relative to the robot arm, comprising a fastening device for attaching the welding torch device to the welding robot, a receiving device for holding a welding torch and for transmitting driven rotary movements to the welding torch, an electrical connection for a welding current cable, by means of which a robot side of the welding torch device can be electrically connected to a welding current source, a current transmission device via which the welding current cable can be electrically connected to a welding torch side of the welding torch device, the current transmission device having a stator which is provided for a non-rotatable arrangement with respect to the robot arm, but which is relatively rotatable with respect to the connection device on the welding robot side, a passage of the stator through which at least one of the consumables required for the welding process can be passed in the direction of the receiving device, the receiving device and the fastening device are designed as a rotor, which can thereby be rotated relative to the stator, and the receiving device and/or the fastening device can be connected to the stator in an electrically conductive manner by means of an electrical contact device, wherein the attachment device of the rotor is designed to be attached to the connection device of the robot, and due to the attachment to the connection device of the robot, an axis of rotation of the rotor is at least substantially aligned with the axis of rotation of the connection device of the robot and the rotor is rotatable about the axis of rotation and about the stator.

26. Arc welding torch device according to claim 25, characterized by a recess running along the axis of rotation of the rotor, which runs centrally with respect to the axis of rotation both through the fastening device (109) and through the receiving device (110), both an inlet opening of the recess in the stator and an outlet opening of the recess in the rotor are being arranged centrally with respect to the axis of rotation.

Description:
ARC WELDING TORCH

[0001] The invention relates to an arc welding torch device, having a consumable electrode, wherein the electrode is provided with a direction of movement from a rear end of the arc welding torch device for feeding in the direction of a front end of the arc welding torch device, in the region of which the electrode is consumed during an arc welding process, the electrode in the arc welding torch device is guided in an exchangeable wire core, the wire core being arranged at least in the region of the rear end of the arc welding torch device in a guide element surrounding the wire core and designed as an exchangeable wear part, and the guide element of the wire core being provided for the joint exchange of the wire core due to wear. Such an arc welding torch device can preferably also be provided with a media feed for a protective or active gas and for electrical current.

[0002] Numerous different welding processes exist. The present invention has particular relevance to arc welding. Arc welding is based on the heat generated by an electric arc between a welding electrode and a workpiece on which welding is carried out. Due to the generation of heat, the material or materials to be welded can be melted locally. In almost all arc welding processes, a shielding gas is supplied to the region of the arc, in order, on the one hand, to enable a resistance-reducing ionized atmosphere between the welding electrode and the workpiece and, on the other hand, to prevent oxidation of the welding electrode and the workpiece. Rather than an inert gas used in this case as a shielding gas, an active gas or a mixed form which is used for the reaction can be supplied instead. Likewise, electrodes can be provided that do not require an external gas supply, since the substances required for this are integrated in the electrodes and are released when the electrodes melt.

[0003] An arc welding torch is usually designed so that a user or a robot can point a metal welding wire, which can also be referred to as a metal filler material, at a specified joint on the target metal piece. The welding wire is guided through the welding torch and finally transported to the target metal piece through an opening in the contact tip at the end of the welding torch facing the workpiece. [0004] When an electrical voltage is applied to the welding torch internal tube and when the welding wire comes into contact with the target metal piece, a high electrical current flows from a welding torch internal tube via a so-called tip adapter, then over the contact tip, over the welding wire, and possibly an arc to the target metal piece, and then to the ground. The high current and the arc cause the welding wire to melt in a shielding gas atmosphere, which leads to the formation of droplets in the wire and the creation of an arc.

[0005] This arc melts the metal of the target metal pieces and the welding wire which is fed thereto. These are connected to each other by the drops of the welding wire falling off or by the drop being transferred in a short circuit to the liquefied point of the target metal pieces. Due to the small distance from the contact tip and the gas nozzle to the arc and/or the heated target metal piece, these components are heated to a high temperature. Due to the high thermal load, the contact tip in particular is subjected to heavy wear.

[0006] Most commonly, the front end portion of conventional torch systems, on the welding process end, are substantially composed of the contact tip, the tip adapter and the outer gas nozzle. These components are usually detachably mounted on the neck (external tube, internal tube) and thermally or electrically coupled to each other or to other components of the neck via contact surfaces or threads, and/or insulated. However, the external tube must be electrically decoupled from other live components, since for safety reasons it can receive no voltage. The thermal coupling of the components is an attempt to dissipate the energy that is introduced into the contact tip or gas nozzle in the form of heat via the external tube or internal tube as effectively as possible, and to thereby lower the maximum temperature of the contact tip in order to minimize wear.

[0007] In the case of arc welding torch devices of the generic type, the welding wire of the arc welding torch device, which functions as a consumable electrode, and the protective gas - in cases where the given welding process involves such a gas - are supplied in the region of the device rear end. The welding wire is fed through the interior of the arc welding torch device from its rear end to the exit from the front, process-side end according to the consumption. For this purpose, a wire feed means which is known per se is arranged in the region of the rear end, and feeds the welding wire - for example, by means of a driven pair of wheels - and moves it through the interior of the arc welding torch device. In order to protect the arc welding torch device itself from wear due to the feed movement of the welding wire, the welding wire is usually arranged in a so-called wire core. The wear in the interior of the arc welding torch device due to the feed movement of the welding wire therefore takes place primarily in the wire core and not on components of the housing of the arc welding torch device. The latter thus wears out instead of other components inside the arc welding torch device. As a result, it is necessary that the wire core is replaced from time to time.

[0008] Conventionally, for the wear-related replacement of the wire core, it is necessary for the welding torch to be dismantled, in particular also and above all the other rear end of the arc welding torch facing away from the end on the welding process side, which is located opposite the wire feed means. This is associated with great expenditure of time for the disassembly and assembly of the arc welding torch device. A solution is therefore already known from EP 1 658 155 B1 , in which the wire core is exchanged from the welding process end of the arc welding torch device. To dismantle and remove the wire core, only the front end of the arc welding torch device has to be disassembled, wherein a connection of a guide means for the wire core with other components of the arc welding torch device must be released and the guide means must be removed together with the wire core. Then, a new wire core together with the guide means is reinserted into the welding torch from the front, pushed through to the rear end of the welding torch and the guide means is detachably fastened again inside the arc welding torch device.

[0009] A disadvantage of this solution is that, in particular, the assembly of the wire core in the region of the rear end of the arc welding torch device must be carried out blindly and it is therefore not possible to check whether the newly introduced components are correctly arranged and assembled. A faulty assembly becomes apparent only after the arc welding torch device has been put back into operation if, due to the faulty assembly of the arc welding torch device, it does not work as intended and/or expensive scrap is produced with it. A time-consuming and costly renewed disassembly and assembly of the arc welding torch device and a temporary shutdown of a welding system associated with high investment costs must then take place.

[00010] The invention is therefore based on the object of creating a possibility, in the case of an arc welding torch device of the type mentioned at the outset, of being able to better control and assess correct assembly of a replaced wire core.

[00011] This object is achieved according to the invention in an arc welding torch device of the type mentioned in that a predetermined end position is provided in the arc welding torch for the guide element with regard to its direction of insertion into the arc welding torch, and when it is reached by the guide element, a position signaling means signals the correct position of the guide element. In a preferred embodiment of the invention, the position signaling means signals the correct position by means of a signal that can be perceived outside or from the outside of the arc welding torch device. It is particularly preferred if the position signaling means is designed as a position indicating means which is arranged outside the arc welding torch device and which can be perceived from the outside as a visual signal when the target position of the guide element is reached. In principle, however, other embodiments of the position signaling means as a visually perceptible position indicating means are also conceivable. For example, an electrical signal could be triggered or interrupted by correctly positioning the guide element, which receives the wire core and is introduced into the arc welding device together with it, which is then made perceptible to an operator using suitable means. Likewise, when the intended target position of the guide means or the wire core is reached, an acoustic signal or a signal that is visually perceptible on a display means could be generated.

[00012] In a further particularly preferred embodiment of the invention, it can be provided that the guide element is guided with one of its ends through an outer, end- side housing part of the arc welding torch device, in particular together with the welding wire, and in this case, in the position of use of the guide element in the arc welding torch device, protrudes to the outside out of the outer housing part of the arc welding torch device. The outer housing part can in particular be an end cap of the arc welding torch device, which is connected to a jacket tube extending over the longitudinal axis of the arc welding torch device. [00013] In order to be able to fulfill both the function of a secure arrangement of the wire core inside the arc welding torch device in the area of its rear, wire feed-side end and the function of a position indicator means with a guide element, it can be particularly advantageous that the guide element is formed as a sleeve with - in relation to its longitudinal extension along its longitudinal axis - different sized diameters of its outer surface. This makes it possible to use at least one section of the guide means for precise positioning according to a predetermined target position along the longitudinal axis of the arc welding torch device and another section of the guide means as position indicator means protruding from the housing of the arc welding torch device. The at least one section of the guide means with the larger diameter can abut against a stop in the interior of the arc welding torch device when it is in the desired position. Such a predetermined position of the guide means can then be signaled in a visually perceptible manner by the at least one portion of the guide means with a smaller diameter outside the housing of the arc welding torch device. This section can thus take over the function of the position display means. In this context, it can be particularly preferred that, viewed in the direction of insertion of the wire core in the arc welding torch device, the section with the smaller outer diameter, in particular with the smallest outer diameter, is located in front of the at least one section with one or more larger outer diameters of the guide means.

[00014] In a further preferred embodiment of the invention, a sleeve-shaped inlet body can be provided which is connected, in particular detachably connected, to the housing of the arc welding body. The housing can in particular be a casing tube that also has the outer surface of the casing of the arc welding torch device and/or an end cap attached to the casing tube at the end. The sleeve-shaped inlet body can be provided with a cylindrical recess extending in the direction of the longitudinal axis. The cylindrical recess can preferably have a constant diameter, which serves as a receptacle for the guide body, in which the guide body is preferably arranged without connection. In the region of its outer surface, the sleeve-shaped inlet body can be connected to the housing of the arc welding torch device, in particular it can be detachably connected, for example by means of a threaded connection. The inlet body can preferably be connected to an end component of the housing, for example an end cap. In the region in front of the front end of the inlet body, a through recess of the end- side component of the housing can be provided with a shoulder so that a position stop is formed for the inlet body in the direction of insertion of the exchangeable components, wire core and guide body. In the further course, the through recess of the end component can preferably taper conically, wherein the conical section can advantageously be provided as a push-in delimitation of the guide element.

[00015] It can also be advantageous that the guide element is sealed against both the end cap and the sleeve-shaped inlet body with a sealant in order to avoid leaks of the protective gas supplied to the welding process point inside the arc welding torch device. In this case, one of the sealing means can preferably be arranged on the outer jacket surface between two sections of the guide body with different diameters. The section with the smaller diameter can be the section of the guide element, the end of which protrudes from the end cap when it is correctly positioned. The other section with the larger diameter can preferably be that section of the guide element with which the guide element is arranged in the inlet body, preferably without connection but nevertheless with as little play as possible. This first sealing element is particularly preferably arranged on a conical section between the two sections with a larger and a smaller diameter and also rests against the through hole of the end cap, preferably in the area of a conical section of the through hole. As a result, the sealing element does not generate any relevant holding forces between the guide element and the inlet body, so that the guide element together with the wire core can be released from the arc welding torch device particularly easily and without releasing holding or connecting forces.

[00016] The second sealing element is preferably arranged on a section of the outer jacket surface of the guide element with a larger diameter. This section is preferably designed with a larger diameter than a section with a constant diameter and is located within the cylindrical recess of the inlet body.

[00017] In a further preferred embodiment of the invention, it can be provided that the guide element is held non-positively or positively in the inlet body. This makes it possible to achieve additional security that the guide element remains correctly positioned not only when it is inserted into the arc welding torch device but also during its operation.

[00018] In an alternative embodiment of the invention, a solution can also be advantageous in which the guide element receiving one of the ends of the wire core is arranged in its end position - even during the use of the arc welding torch device - without a holding force within the arc welding torch device. Since the position signaling means preferably continuously signals this not only during the insertion process but also during operation, but at least when necessary, with a correctly positioned arrangement, it is also possible to do without a holding force. If a deviation of the guide element from its intended position is determined on the basis of the position signaling means, appropriate action can then be taken. This solution also has the advantage that, due to the lack of holding force, the assembly comprising the wire core and the guide element can particularly easily be pulled altogether out of the arc welding device from the front, in the area of the process point, from the arc welding torch device at least essentially without overcoming a holding force, without having to dismantle the arc welding torch device itself, in particular at its rear end.

[00019] The object is also achieved by an assembly for exchanging the wire core according to claim 12.

[00020] The aspect of the invention relating to the interchangeable assembly is based on the idea of being able to ensure a position-correct arrangement of the interchangeable assembly introduced from the front, from the welding process-side end of the arc welding torch device, so that reaching or not reaching the intended position of the blind and jointly inserted wire core and guide body can be checked from the outside, in particular visually checked. Since the arrangement must be made in the non- visible interior of the arc welding torch device, an externally perceptible position signaling means, in particular a visually perceptible position indicator, is an enormous help in avoiding incorrect positioning of the wire core and the at least one guide element of the replaceable assembly inserted from the front. It is preferred here that the position signaling means, in particular position indicating means, only signals a correct actual arrangement in the desired position in the interior of the housing when the guide means belonging to the wire core and the jointly exchangeable assembly has actually reached the end position.

[00021] A specific solution that is technically particularly easy to implement can provide that the position signaling means, in particular position indicating means, is part of the guide element or another component of the replaceable component assembly, which is installed in the respective arc welding torch device due to wear and in exchange for a component assembly of a worn wire core. This position signaling means, in particular position indicating means, should thus be inserted into the arc welding torch device together with the assembly at the process-side end and passed completely through the arc welding torch device up to its rear end through the arc welding torch device. When the intended end position of the guide element in the arc welding torch device is reached, the position signaling means, in particular position indicating means, of the exchangeable assembly should emerge again from the housing of the arc welding torch device in the area of the rear end facing away from the process side and thus be visually perceptible from the outside.

[00022] According to a further aspect of the invention, the risk of the welding wire kinking due to its feed movement and due to the entry into a narrow recess of the arc welding torch device provided on the end face is to be reduced. In an arc welding torch device of the type mentioned at the outset, this object is achieved according to the invention by a kink protection means for the welding wire in which the welding wire is guided, protruding from the arc welding torch device and arranged between an outer end cap of the housing of the arc welding torch device and the wire feed means, as described in particular in claim 17.

[00023] A preferred further development of an embodiment of this aspect of the invention can provide that the kink protection means is detachably arranged in the arc welding torch device and a section of the kink protection means protrudes from a recess in the end cap of the arc welding torch device. This makes it particularly easy to provide the kink protection means as a replaceable wear part. Since the kink protection means is arranged in the interior of the housing of the arc welding torch device, it can preferably be designed as a component of the assembly, which is replaced as a whole with a new assembly of this type when the wire core is worn. In connection with a kink protection means for the welding wire provided in the area of the wire feed end of the arc welding torch device, it can also be advantageous that the kink protection means is sleeve shaped and has a continuous recess for receiving the welding wire, and preferably a boundary wall of the continuous recess in the side of the wire feed end is provided with a bevel. The recess here preferably runs concentrically to the intended course of the longitudinal axis of the welding wire. It can also be favorable that a diameter of the recess is matched to the diameter of the welding wire in such a way that the welding wire is safely guided in the recess and nevertheless experiences as little resistance as possible when moving through the recess. The bevel can support a safe and kink-free entry of the welding wire into the kink protection means.

[00024] The present invention can be particularly advantageous in connection with automated welding processes in which an arc welding torch is guided and moved by a welding robot. The problem here is that in order to replace a worn wire core, it is possible that not only the arc welding torch device itself has to be completely or partially dismantled. It may also be necessary to remove the arc welding torch device itself from the robot so that there is access to the wire core and an exchange of the wire core is made possible. The more extensive the disassembly which must take place, the more extensive and time-consuming the subsequent assembly will be. Due to the disassembly, there may even be another time-consuming teach-in of the welding robot with the arc welding torch device attached. The exchange of wire cores from the welding process end according to the invention, together with the position signaling means according to the invention, can therefore have particular advantages for preventing extensive disassembly and subsequent re-assembly of the automatic welding system. Accordingly, the wire core can be exchanged quickly and without extensive disassembly work, wherein the new wire core can nevertheless be arranged in the correct position inside the arc welding torch device.

[00025] In connection with the present invention, this advantage can be particularly pronounced when a hollow shaft robot, such as a “Motoman” type robot, produced as a welding robot by the manufacturer Yaskawa Europe GmbH, 65760 Eschborn, Germany, is used as the robot. In such hollow shaft robots, the welding media, such as the welding wire, protective gas, and electric current, are guided substantially or at least approximately concentrically with the axis of rotation of the hollow shaft through the mount used for attaching the arc welding torch to the robot, said mount being designed as a rotationally driven hollow shaft. Disassembling the arc welding torch device itself and the robot mount is particularly labor-intensive in this case. Such a hollow shaft robot and a particularly advantageous solution for an arc welding torch that interacts with this hollow shaft robot is described, for example, in EP 1 689 550 B1 . The content of that disclosure is hereby fully incorporated by reference. [00026] A preferred arc welding torch, which is provided for arrangement on a welding robot with a robot arm, can therefore have a connection device which can be rotated relative to the robot arm and which comprises a fastening device for attaching the welding torch device to the welding robot, a receiving device for mounting a welding torch and for the transmission of driven rotary movements to the welding torch, an electrical connection for a welding power cable by means of which a robot side of the welding torch device can be electrically connected to a welding power source, and a power transmission device via which the welding current cable can be electrically connected to a welding torch side of the welding torch device. The power transmission device can have a stator which is provided for a non-rotatable arrangement with respect to the robot arm, but which is rotatable with respect to the connection device on the welding robot side. Furthermore, there can be a bushing of the stator through which at least one of the consumables required for the welding process can be routed in the direction of the receiving device, wherein the receiving device and the fastening device are designed as a rotor, and are accordingly rotatable relative to the stator. The receiving device and/or the fastening device can be connected to the stator in an electrically conductive manner by means of an electrical contact device, wherein the fastening device of the rotor is designed for attachment to the connection device of the robot. Due to the attachment to the connection device of the robot, an axis of rotation of the rotor is at least substantially in alignment with the axis of rotation of the connection device of the robot, and the rotor is rotatable about the axis of rotation and about the stator.

[00027] It can furthermore be preferred that, in an arc welding torch device according to the invention, a recess is provided which runs along the axis of rotation of the rotor and runs centrally (in alignment) with respect to the axis of rotation through both the fastening device and the receiving device, wherein both an inlet opening of the recess in the stator and an outlet opening of the recess in the rotor are also arranged centrally and thus in alignment with respect to the axis of rotation. In this particularly preferred solution for hollow shaft robots, the inlet opening in the arc welding torch for welding media coming from the welding cable is thus located along the axis of rotation of the arc welding torch. The outlet opening for the exit of welding media from the rotor and its transfer into the welding torch neck is also in alignment with the axis of rotation of the rotor. The entire recess thus preferably runs along the axis of rotation of the rotor and thus also of the robot-side connection device with which rotational movements of the rotor around the stator are generated and transferred from the robot to the rotor. [00028] In such a preferred embodiment of the invention, the welding wire can thus be inserted into the arc welding torch device at the wire feed end and passed through the wire core to the end of the arc welding torch device on the process end. While the arc welding torch device is in use, the welding wire continuously fed because of the welding wire tip melting off in the region where the process takes place. The welding wire is accordingly moved longitudinally through the entire arc welding torch device, and thus also through the connecting flange of the hollow shaft robot for the arc welding torch and through its stator. To replace the wire core and its assembly, the arc welding torch device must preferably only be slightly disassembled in the region of its process-side end, so as to allow access to the process-side end of the wire core, which can then be completely pulled out of the arc welding torch and its process-side end by hand. The arc welding torch device remains assembled on the connection flange of the hollow shaft robot, and both the worn and the new wire core and the associated assemblies, preferably including the position signaling means and/or preferably the kink protection means, are moved inside the arc welding torch and thus through the robot- side connection flange. The exchange of the wire core can thus be carried out extremely quickly and reliably with little effort, even with a hollow shaft robot.

[00029] Further preferred embodiments of the invention emerge from the claims, the description and the drawing. [00030] The invention is explained in more detail with reference to embodiments shown purely schematically in the figures, wherein:

[00031 ]Fig. 1 is a preferred embodiment of an arc welding torch device according to the invention, together with a wire feed device;

[00032]Fig. 2 is a sectional illustration of a rear end region of the arc welding torch device of Fig. 1 ;

[00033]Fig. 3 is an exploded view of the detail of Fig. 2;

[00034]Fig. 4 is a sectional view of a rear end region of a further embodiment of an arc welding torch device according to the invention;

[00035]Fig. 5 is an exploded view of the detail of Fig. 4;

[00036]Fig. 6 is a highly schematic illustration of an articulated arm robot used as a welding robot;

[00037] Fig. is a highly schematic basic sectional illustration of an embodiment of a welding torch of an arc welding torch device;

[00038]Fig. 8 is a more detailed illustration of the welding torch device of Fig. 7;

[00039] Fig. is a stator of the welding torch device of Fig. 8 together with a slide contact device, in a sectional view;

[00040]Fig. 10 is a side view of the assembly of Fig. 9;

[00041 ]Fig. 11 is an embodiment of a suitable articulated arm robot; [00042]Fig. 12 is an enlarged detailed illustration according to line A of Fig. 11 .

[00043]Fig. 13 is a cross-sectional view of the slide contact device of Fig. 10;

[00044] Fig. 1 shows a preferred embodiment of an arc welding torch device 1 according to the invention. The arc welding torch device 1 is intended for use in an automatic welding machine, such as a welding robot, which is not shown in detail. The arc welding torch device 1 is arranged on an end manipulator of the robot, not shown in detail, which can be moved in different spatial directions, preferably in all spatial directions on any desired feeding paths. The end manipulator can thereby carry the arc welding torch 1 along its feeding path, and the arc welding torch 1 can create welded seams on workpieces. The arc welding torch can in principle be designed in the same way as the arc welding torch disclosed and described in WO 2005/049259 A1 , wherein differences with regard to the end region of the arc welding torch are seen in Fig. 1 , and will be discussed below. Due to the not absolutely necessary, but particularly preferred embodiment of the arc welding torch 1 , according to which it has an external stator part and an internal rotor part and the welding point is fed and supplied with welding media at least substantially along and coaxially with a longitudinal axis 3 of rotation of the arc welding torch device and the end manipulator, the welding torch can be continuously rotated, and twisting of a welding cable during rotational movements can be avoided. It is explicitly pointed out that the arc welding torch shown and discussed here is only given as an example of the invention and the invention can in principle also be used in connection with other types of arc welding torches - and in particular with arc welding torch devices having a specific structure which differs from the structure of the arc welding torch device discussed below.

[00045] The arc welding torch device 1 shown merely as an example for the invention is a welding torch 1 operating according to the gas-shielded metal arc welding method. In this case, a welding wire 7 which is consumed during the welding process is fed to the intended welding point, and is continuously advanced during a welding process as a result of the consumption of the welding wire 7. The welding wire 7 in this case is most commonly fed through the interior of the welding torch 1 , primarily through a jacket tube 2, together with its wire core 8a and preferably an insulation surrounding the welding wire. In addition, a shielding gas is supplied to the welding point, most commonly also through the jacket tube 2. In this embodiment, the shielding gas is an inert gas; in other embodiments according to the invention, an active gas - or a mixed form of both - can also be supplied as the shielding gas. In the preferred embodiment, current is also supplied into the arc welding torch device 1 in the region of the rear end 6 of the arc welding torch device and passed through the arc welding torch device to the welding or process point, and is used at the welding point or in the region of the welding process end 5 of the arc welding torch device to ignite an arc and maintain it for the welding process. The arc welding torch device 1 , when used, is therefore connected to or provided with a welding power source (not shown) and a wire feed means 12. In preferred embodiments, the welding wire, the shielding gas, and the current can be fed to the arc welding torch at its power connection point via a welding cable known per se, in particular a coaxial welding cable. At a gas connection point of the arc welding torch device 1 , the shielding gas is introduced into a duct 9 of the welding torch 1 in its interior, to guide the shielding gas through the same from the connection point to the free end at the welding point. The current is likewise conducted from the welding cable through the welding torch 1 to the welding or process point. The current is also conducted inside the welding torch to the process point in such a way that an outer side of the arc welding torch device 1 is current-free.

[00046] The arc welding torch device 1 accordingly has a torch neck 4 which is connected to a cable-hose assembly 2. The cable-hose assembly 2 runs approximately from the rear end 6 of the arc welding torch device 1 to the welding torch at the front end 5 on the welding process end. In the region of the rear end 6, which is shown in Fig. 2, several exchangeable wear parts are arranged in the interior of the arc welding torch 1 ; these will be discussed in more detail below.

[00047] In Fig. 2, the rear end 6 of the arc welding torch device 1 which is remote from the welding process point and the associated open front end 5 of the arc welding torch device 1 is shown in a detailed view, together with two drive rollers 10, 11 of a wire feed device 12. In this illustration, the welding wire 7 is shown between the two drive rollers 10, 11 with their peripheral surfaces opposite each other. The drive rollers 10, 11 are located directly opposite the rear end 6 of the arc welding torch device 1 which is remote from the process point of the arc welding torch 1 . This front end 6 of the approximately tubular jacket tube terminates with an end cap 14 which has a through-hole 16 (Fig. 3) along the central axis 3 of the housing 14, which is open towards the front outer end of the end cap 14. The end cap 14 is open towards the process end of the arc welding torch device, and from there is provided, in the direction of the open through-hole 16, with a stepped central recess 17. The latter initially has a constant, greater diameter 18, which merges into a constant diameter 19 of the recess which is smaller in comparison. This region in turn transitions into the through-hole 16. The inner peripheral surface of the smaller diameter portion 19 is provided with an internal thread 19a. Likewise, the inner circumferential surface of the region of the greater diameter 18 also has an internal thread 18a. The latter extends until shortly before the transition to the smaller diameter 19.

[00048] The outer/shell surface of the end cap 14 has a section 14a which widens conically from the end in the direction of the process point, and which merges into a section 14b of the shell surface with a constant diameter. With its end face 20 facing the process point, the end cap 14 abuts an outer shoulder 21 of the jacket tube 2 of the arc welding torch 1 . The jacket tube 2 protrudes into the area of the greater inner diameter 18 of the end cap 14 until shortly before the transition to the smaller diameter 19. An inner diameter 23 of a through-recess of the jacket tube 2 in the region of its front end corresponds to the smaller diameter 19 of the recess 17 of the end cap 14, such that a sleeve-shaped inlet body 25 can be received by its outer shell surface in the jacket tube 2, at least substantially with a positive fit. To secure the position of the sleeve-shaped inlet body 25 in the axial direction, the through-recess 24 of the jacket tube 2 has a shoulder 26 with a smaller inner diameter, the shoulder being provided as a stop for the inlet body 25.

[00049] In the region of the jacket tube 2, a cut-in 28 or a radially circumferential groove is formed on the outer shell surface or on the outer shell surface of the sleeve shaped inlet body 25, which is intended to receive a sealing element 29 or sealing means, such as an O-ring in particular. A section of the outer surface of the inlet body 25, which is located opposite the smaller diameter 19 of the recess of the end cap 14, is provided with an external thread 30, which can be screwed into the internal thread 19a of the cylindrical circumferential surface of the section of the recess 17 of the end cap 14 with the smaller diameter 19.

[00050] The sleeve-shaped inlet body 25 is formed with a through-recess 25a which is provided with a continuously constant inside diameter. Only in the region in which a guide element 32, preferably without a connection to the inlet body, is situated in the through-recess 25a of the inlet body 25, does the recess 25a have a cut-in 25b or groove for the arrangement of a sealing element 33 or sealing means, such as an O- ring in particular. The sealing element arranged in the groove 25b of the inlet body 25 thus has contact with the outer shell surface of the guide body 32.

[00051] The inlet body 25 has an outer shell surface with different sections which differ from each other primarily in the size of their outer diameter. In the embodiment shown, a first section of the outer shell surface close to the rear end of the arc welding torch has the external thread 30 with which the inlet body 25 is screwed into the internal thread 19a of the end cap 14, and thereby detachably connected to the end cap 14. Towards the process end 5 of the arc welding torch device 1 , the external thread 30 is followed by a cut-in 35, which in turn is followed by a threadless section 36 of the outer shell surface, which has the same external diameter as the threaded section 30. The threadless section 36 has the circumferential groove 28 in which the further sealing element 29 can be received - in the case of the embodiment shown, an O-ring.

[00052] In the direction of the process end 5, a further, final section 37 of the outer shell surface of the inlet body 25 then follows, which also has a constant but smaller outer diameter than the preceding section. The shoulder 38 formed by means of the change in diameter between the last section 37 of the outer jacket surface and the section 36 preceding it results in an insertion or rotation limitation for the jacket tube 2 on the inlet body.

[00053] The jacket tube 2 in turn has in the region of its front end, on its outer shell surface, an external thread 39, onto which the end cap 14 is screwed with its internal thread 18a. The screwing-in movement is limited by the end face 20 of the end cap 14 impacting the shoulder 21 of the jacket tube. Reaching this position can constitute a visual check that the end cap is correctly mounted and screwed.

[00054] In Fig. 3, the wire feed end or rear end 6 of the arc welding torch device 1 is shown in an exploded view and a situation which occurs when changing the wire core 8a. As can be seen here, the inlet body 25 is screwed into the end cap 14 during operation of the arc welding torch device 1 . Likewise, all seals are inserted in their grooves and remain there even when the wire core is changed. In the illustration of Fig. 3, the jacket tube 2 is not shown; it is connected, unchanged, to the end cap 14 by the shared screw connection, and remains connected even during the change of the wire core 8a. In order to change the wire core 8a, the arc welding torch is first disassembled at the process end 5 so that the wire core 8a and the guide element 32 can be pulled out of the process end 5 together. In a current arc welding torch of the applicant, in which the invention described here is to be integrated in the future, the gas nozzle, a current contact tip, and optionally a tip adapter, by way of example, can be detached from the arc welding torch and removed from the welding wire. The wire core 8a can then be pulled out of the arc welding torch from the process end 5. The guide body 32 seated on the wire core 8a and connected to the latter by a press fit is pulled out of the arc welding torch device 1 together with the wire core. The guide element, which is seated in the recess of the end cap and the recess of the inlet body in this embodiment largely without connection to the two components, can thus be pulled out of the two components and out of the arc welding torch 1 together with the wire core 8a without additional effort, in particular without great effort. When this assembly is pulled out, only a comparatively low holding force acting on the shell surface of the guide element via an O-ring seal has to be overcome.

[00055] A new wire core 8a can then be arranged with one of its two ends on the welding wire 7 and inserted into and arranged in the guide body 32. The guide body 32 and the wire core 8a on the welding wire 7 can then be pushed together in a single operation into the welding torch and thus also into the arc welding torch device 1 . This insertion movement in the direction of the end cap 14 is continued until the guide body 32 with its end 32a on the end cap, serving as a position indicator, is completely passed through the open through-recess 16 of the end cap 14, and the end 32a of the guide element 32 protrudes outwards out of the end cap 14. The visually recognizable end of the guide element 32, with one of its ends 32a arranged outside of the arc welding torch device 1 , provides a means of checking, without additional technical outlay, whether the guide body 32 and the wire core 8a are arranged in their predetermined target positions inside the arc welding torch device 1 . Since the guide body 32 is only sealed against leakage of the shielding gas flowing in the arc welding torch device in the intended positions thereof, the end 32a of the component of the guide body 32 that is visible outside the end cap 14 also provides a check to determine whether the newly inserted wire core 8a and its guide bodies 32 are arranged in such a way that the arc welding torch 1 is sealed against the escape of shielding gas from the end 6 of the arc welding torch 1 at the end cap.

[00056] The component of the guide body 32 comprises the cylindrical end region section 32a facing the wire feed device when in the position of use on the arc welding torch 1 , which in this embodiment is elongated and has a constant outer diameter. The end region section 32a merges into a section 32b which enlarges conically towards the end 5 on the process side, which is adjoined by a cylindrical section 32c with a greater, preferably constant, outer diameter. In the embodiment in Fig. 2 and 3, the section 32c has a shoulder with a slightly reduced outer diameter. When it is inserted into the arc welding torch device 1 , the guide body 32 is inserted into the inlet body 25 with its end region 32a first. Since a front, outside diameter of section 32c in the insertion direction corresponds approximately to the inside diameter of the through-recess 25a of the inlet body 25, the guide body is guided within the inlet body during its feed movement. As a result, the end region section 32a is also aligned in the correct position and arranged concentrically around the longitudinal axis 3, and can be inserted into the through- recess 16 of the end cap 14. Since the end region section 32a has a constant outer diameter which is only slightly smaller than the diameter of the through-recess 16, the end region section 32a can be completely inserted into the through-recess, and part of the end region section 32a can be pushed out of the through-recess 16 of the end cap. This part of the end region section, which can be referred to as a position indicator means, is thus recognizable from the outside in its end position in the welding torch 1 , and is located comparatively close to the point of engagement of the wire feed device at which the feed movement is applied to the welding wire 7. This position indictor means can be used for a signalization which is visually perceptible from the outside, showing that the guide body and the wire core 8a are correctly positioned in the interior of the arc welding torch.

[00057] The single-piece component of the guide body 32 is provided with a through-recess 34 which, in the region of the end region section 32a, has a preferably constant diameter which is only slightly greater than the diameter of the welding wire used in this case. In the region of the section 32c with the greater outer diameter, the through-recess 34 has a greater, but also constant diameter, such that the rearward end of the wire core 8a can be arranged in this region of the through-hole. The inside diameter of the recess 34 in this area corresponds approximately to the outside diameter of the wire core. With its front end, the wire core 8a abuts the shoulder 34a resulting from the change in diameter in the through-recess 34. The single-piece construction of the guide body 32 results in good guiding properties for the welding wire in the guide body 32, with at most a low risk that the welding wire 7 will get caught during its movement and thereby buckle.

[00058] Beveling the opening of the through-recess 34 in the region of the end face of the end region 32a of the guide body can contribute to preventing the welding wire 7 from getting caught on or in the guide body 25 during the feed movement, and to facilitating the insertion of a welding wire end into the guide body 25.

[00059] Different guide elements 32 with different diameters of the through-recess 34 can also be provided for different welding wires. Such a system can in particular have guide bodies which are identical in their geometrical outer shape, but which differ in terms of the diameter of their respective through-recesses 34, and optionally also in terms of the materials used for the guide elements, such that an adaptation to the given material of the welding wire can take place in an advantageous manner.

[00060] The end 32a, protruding from the end cap 14, of the component of the guide element 32 in which the welding wire 7 is guided also shortens the free and unguided length of the welding wire between the wire feed device and the arc welding torch device 1. Due to the smaller outer diameter of the end of the component of the guide element 32 compared to the front end of the end cap, the component of the guide element protruding from the arc welding torch device can be arranged closer to the contact point of the welding wire with the two feed rollers of the wire feed device. The welding wire is thus received earlier by the component of the guide element and guided by it, which reduces the risk of the welding wire kinking. The section of the component of the guide element with the smaller outer diameter, which is guided through the end cap 14 and protrudes from it, can be referred to as an anti-kink means.

[00061] The invention also has the advantage that, unlike in the past, the end cap 14 neither guides nor touches the welding wire 7 nor the wire core 8a, and thus the end cap 14, which is usually complex, is no longer a wear part.

[00062] In the illustrations of Fig. 4 and 5, a further preferred embodiment of the invention is shown. This is largely identical to the preferred embodiment of Fig. 1 to 3, which is why only the differences will be discussed below in order to avoid repetitions. The above description of Fig. 1 to 3 is therefore also incorporated by reference for the embodiment in Fig. 4 and 5.

[00063] The main difference to the embodiment of an arc welding torch device according to Fig. 1 - 3 is that the guide element 32 has (only) one section 32c with a greater diameter, which has a continuous, constant diameter after its conical section 32b in the direction of the process end of the welding torch. In this preferred embodiment, there is no increase in diameter on the outer jacket surface of the guide element following the conical section - and viewed in the direction of the process-side end - which could be used for a form-fitting and/or force-fitting holding of the guide element. In addition, in this preferred embodiment, no sealing element, such as the sealing element 33 of the other embodiment of Fig. 2 and 3, rests against the outer circumference of the section 32c with a constant diameter. As such, there is also no sealing element between the inlet body 25 and the guide element 32 which could exert a holding force on the guide element 32 on the guide element 32. This has an advantage especially for changing the wire core 8a, since due to the lack of holding force on the guide element 32, the wire core and the guide element can be removed more easily - that is, with less effort - from the arc welding torch device towards the process end. Flowever, since the arc welding torch devices according to the invention have signaling means with which the correct position can be checked by means of the signaling means, preferably during the entire use of the arc welding torch having a certain wire core, additional holding forces are also not absolutely necessary.

[00064] Fig. 6 - 13 show, among other things, a type of articulated arm robot 101 which is already used in many ways. The articulated arm robot 101 is designed as a so-called hollow shaft robot, which is particularly suitable in connection with the invention. Such suitable robots can be, for example, the robots of the AR or MA series, which are produced by the company Yaskawa Europe GmbH, 65760 Eschborn. The robot has a frame part 102 and an arm 103 which is arranged thereon and which is provided with a plurality of joints 104. The free end 105 of the arm of the articulated arm robot 101 is thus able to travel along any three-dimensional movement paths.

[00065] At the free end 105 of the arm 103, the robot is provided with a connecting flange 106 of a connection device which is provided for receiving a welding torch 107 (Fig. 6) of the arc welding torch device. The connecting flange 106 can execute a motor- driven rotational movement about an axis of rotation 108 and relative to the last link of the arm 103. In Fig. 6, a spacer block is drawn in front of the welding torch, which serves as an extension of the connecting flange 106 of the robot and can be provided as a non-required option.

[00066] The arc welding torch 107 shown in more detail in Fig. 7 to 10 has a fastening device 109 and a receiving device 110 (Fig. 7). The fastening device 109 is provided to connect the welding torch 107 to the connecting flange 106 of the robot arm 103 in a detachable, but non-rotatable manner. In contrast, the receiving device 110, together with a contact device, serves to receive a welding torch neck 111 of the welding torch 107 and to transmit the welding current to the welding torch neck 111. This transmission is explained in more detail below. Since the receiving device 110 can be connected non-rotatably to the connecting flange 106 of the robot, which executes rotational movements, via the fastening device 109, in a manner which will be explained in more detail below, the receiving device 110 and the fastening device 109 are also jointly referred to as part of a rotor which, by means of driven movements of the connecting flange about the axis of rotation 108, can perform such rotational movements. For this purpose, the rotor is non-rotatably connected to the connecting flange, and in particular is detachably connected. [00067] The rotor can be rotated about the axis 108 relative to the last link of the robot arm 103 to which the connecting flange 106 is attached. The robot shown in the figures has a total of six driven axes, this number being only an example of the possible uses of the arc welding torch. In connection with the arc welding torch according to the invention, articulated arm robots with a different number of driven movement axes can also be used.

[00068] A stationary stator which is positioned inside of the rotor and the last link of the robot arm 103 has a tubular bushing 114 which is arranged centrally in the welding torch device and has a cylindrical recess 115. A longitudinal axis 116 of the recess 115 is aligned with the axis of rotation 108 of the connecting flange 106. The bushing 114 extends approximately over the entire length of the fastening device and the receiving device. The upper end of the bushing 114 on the robot side is provided with an external thread 117 serving as an electrical connection, onto which a coaxial cable 118 (Fig. 6 and 7) can be detachably attached by being screwed thereon. In addition to the thread 117 of the bushing, a cone 119 (Fig. 8) can also be provided as a current-conducting contact between a welding current cable 118a of the coaxial cable 118 and the bushing 114. In the case of such a coaxial cable 118, the welding current cable 118a provided with an outer insulation 118b is arranged coaxially around a central channel 118c. The central channel 118c can serve to feed the welding wire 7 to the welding torch by means of a feed movement and to allow an inert gas to flow to the front end of the welding torch 107.

[00069] In the region of an end on the welding torch side, which is lower in the illustration, the bushing 114 is surrounded by a bell-shaped section 123 (Fig. 8 and 9) of the stator which is circular in cross section and which is electrically conductively connected to the bushing. In the embodiment, the bell-shaped section 123 and the bushing 114 are connected in one piece. A contact device 124, which has a slip ring

125 arranged in the bell-shaped section, is arranged substantially inside the bell shaped section 123 on the bushing 114. The contact device 124 has a contact surface

126 formed on the end face of the slip ring 125. On the one hand, the contact surface 126 is force-loaded by a compression spring 127 acting parallel to the longitudinal axis 116 of the bushing 114. The compression spring 127 is supported on the inside on the bell-shaped section 123 of the stator, and presses the contact surface 126 against a likewise substantially annular surface of a connecting bell 135. Both the annular surface of the connecting bell 135 and the contact surface 126 are components of a contact device 124, and are each arranged concentrically around the longitudinal axes 108, 116 and penetrated by a continuation of the recess 115.

[00070] Between the slip ring 125 and an inside of the bell-shaped section 123 there are contact segments 145 which establish the electrical contact between the slip ring 125 and the bell-shaped section 123. The spring action of the contact segments 145 has the effect that an electrical contact is established between the slip ring 125 and an inner surface 133 of the bell-shaped section 123. The material of the slip ring 125 is a good electrical conductor, for example copper or a copper alloy. The contact segments 145 can preferably accordingly be silver-plated in order to ensure particularly good electrical current transfer. The side of the slip ring 125 facing away from the compression spring 127 with its contact surface 126 (Fig. 9) is designed as a stationary component and as part of the stator, and acts as an electrical transition to the rotor to which the connecting bell 135 belongs, and which is rotatable about the longitudinal axis 108.

[00071] As such, the connecting bell 135 (Fig. 8), which is also electrically conductive due to a preferably silver-plated surface, adjoins the slip ring 125 in the direction of the longitudinal axis 116 of the bushing 114 and in the direction of the welding torch end. The bushing 114, the slip ring 125, and the connecting bell 135 have aligned central holes, which overall are part of a central recess 115 running along the longitudinal axis 108.

[00072] The compression spring 127 thus presses against the slip ring 125, which in turn presses via its contact surface 126 against the connecting bell 135; the latter is therefore constantly in contact with the contact surface 126 - in particular, in electrically conductive contact. The connecting bell 135 is additionally secured in relation to its axial position on the bushing by means of a ring 148. Furthermore, the connecting bell 135 is paired with and is axially centered by the conical outer surface of the “brass flange with bushing” 149 via a conical, silver-plated inner surface. In addition, a seal 136 which makes it possible to ensure that the bell-shaped element 123 sits on the slip ring 125 in a gas-tight manner, as part of the stator, is located between the bell-shaped element 123 of the stator and the slip ring 125 in a groove 150 of the slip ring 125.

[00073] A “brass flange with bushing” 149, which is paired with the preferably silver-plated connecting bell 135 via a cone, is screwed via a plastic insulating sleeve 151 to a fastening element 152, which is part of the fastening device and serves as a counterpart for the welding torch connection.

[00074] The housing 141 , an end cover 142 adjoining one end of the housing 141 , and a cover 154 adjoining the other end of the housing 141 in the direction of the welding torch neck 111 are designed as plastic components in the embodiment. In the embodiment, the housing 141 also contains the fastening device 109 for fastening to the connecting flange 106 on a hollow shaft robot and, together with the cover 154 and the cover 142, electrically encloses and isolates the internal structure. The receiving device 110 of the welding torch is made of metallic, electrically conductive material, but it is also separated from current-carrying components via the plastic sleeve 151 with a flange as an insulator. The receiving device 110 for the welding torch is accordingly routed through the plastic housing 141 and the cover 154.

[00075] The fastening device 109 constructed as part of the plastic housing 141 is non-rotatably but detachably connected to the connection flange of the robot 106. The receiving device 110 for the welding torch, to the fastening element 152 of which a welding torch is detachably connected in a rotationally fixed manner, is also connected non-rotatably to the plastic housing 141. In principle, the housing 141 located on the outside of the welding torch is a component of the rotor of the arc welding torch. This rotor is arranged concentrically with the internal stator of the arc welding torch with respect to the axis of rotation 108, and can rotate about the latter due to motor-driven rotational movements of the connecting flange 106 of the robot relative to the internal stator. In contrast, the stator is stationary when the rotor moves together with the robot- side connecting flange 106, and does not rotate with it. In the embodiment, this stationary arrangement with respect to the connecting flange 106, the fastening device 109 and the rotor can be achieved overall, for example, by the welding cable being fastened to the thread 117 of the bushing 114 and being fixed in its rotative position due to the torsional rigidity of the welding cable. In other embodiments of the invention, an additional rotation lock of the stator on the robot can also be provided.

[00076] This makes it possible to transmit a rotary drive movement of the connecting flange 106 of the robot to the welding torch via the plastic housing 141 , with the aid of a fastening ring 153 arranged in the housing 141 and the fastening element 152. The stator, however, does not perform this rotary movement, since it is rotationally fixed to the robot arm via the coaxial cable 118 - and possibly via further fastening means. The resistance to torsion exhibited by such cables 118 can, however, already be sufficient to fix the stator, although a small proportion of the torque of the drive movement can possibly be transmitted to the stator via the bearings 143 due to frictional torques that cannot be completely ruled out. In the illustrated embodiment, the stator has at least the components: the bushing 114 and the slip ring 125, together with the compression spring 127. The rotor is mounted on the stator by means of bearings 143 - in this embodiment, the ball bearings.

[00077] The plastic housing 141 is closed towards the welding torch with the cover 154, which covers the fastening ring 153. The housing 141 is covered towards the welding torch cable by the end cover 142. Should it appear necessary, the stator can also be additionally fixed to a rotationally fixed component of the robot, for example via the cover 142.

[00078] The electrical current required to carry out a welding process flows, proceeding from the welding current cable 118a, which is connected to the bushing 114 of the stator via the screw connection on the external thread 117, and continues in the stator to the bell-shaped section 123. There are contact segments 145 via which the current is transmitted to slip ring 125, which also belongs to the stator. The current is transmitted to the silver-plated connecting bell 135 via the sliding contact between the contact surface 126 and the connecting bell 135. The connecting bell 135 is part of the rotor and rotates with a driven rotational movement of the connecting flange 106, together with the housing 141 , about the axis of rotation 108. The connecting bell 135 has, on an inner surface, a conical and likewise silver-coated surface 137 which is paired with a counter-cone of the brass flange 149 with bushing, and thus has a tightly pressed fit and accordingly good power transmission properties. In the brass bushing 149, there is a further, electrically conductive contact segment 155 X6, by means of which the welding current is transmitted to the welding torch via an inserted internal tube. The welding torch is fastened via the fastening element 152, which is insulated from the internal tube.

[00079] The shielding gas can flow via the coaxial cable 118 through the recess 115 of the bushing 114 to the welding torch neck 111. The welding wire 7 can also be fed to the welding torch neck 111 in the same way, and continuously advanced. If necessary, a data cable (not shown) can be integrated into the coaxial cable 118.

List of reference symbols Arc welding torch 26 Shoulder Jacket tube 28 Insertion/groove Longitudinal axis 29 Sealing element Torch neck 30 External thread (of 25) Welding-process-side end 32 Guide element Rear end 32a End/end region Welding wire 32b Conical section a Wire core 32c Section Duct 33 Sealing element 0 Drive roller 34 Through-recess 1 Drive roller 34a Shoulder 2 Wire feed device 35 Insertion 3 Housing 36 Threadless section 4 End cap 37 Section with a smaller diameter4a Conical section 38 Shoulder 4 Cylindrical section 39 External thread (of 2) 6 Open through-hole 101 Articulated robot 7 Stepped central recess 102 Frame 8 Greater diameter 103 Arm 8a Inner thread 104 Joint 9 Smaller diameter 105 Free end 9a Inner thread 106 Connecting flange 0 Face 107 Welding torch 1 Outer shoulder 108 Axis of rotation 3 Inner diameter of 2 109 Fastening device 4 Through-recess of 2 110 Receiving device 5 Sleeve-shaped inlet body 111 Welding torch neck 5a Through-recess 5b Insertion/groove Bushing 134 Slip surfacea Longitudinal groove 135 Connecting bell (silver-plated) Recess 136 Seal Longitudinal axis 137 Flange surface External thread 141 Plastic housing Coaxial cable 142 Closing cover a Welding current cable 142a Hole b External insulation 143 Bearing c Channel 145 Contact lamella Cone 148 Ring Bell-shaped section 149 Brass flange with bushing Contact device 150 Groove (of 126) Slip ring 151 Plastic sleeve Slip surface 152 Fastening element Compression spring 153 Fastening ring Recess 154 Cover Compression spring 155 Contact lamella Inner surface