EP3746252A1

EP3746252A1 - Resistance welding device and method for producing a wire netting

Info

Publication number: EP3746252A1
Application number: EP19710571.1A
Authority: EP
Inventors: Hubert RAPPERSTORFER
Original assignee: Apilion Machines and Services GmbH; Apilion Machines Services GmbH
Current assignee: Apilion Machines and Services GmbH
Priority date: 2018-01-29
Filing date: 2019-01-25
Publication date: 2020-12-09
Also published as: WO2019144174A1; AT520866B1; AT520866A1

Abstract

The invention relates to a resistance welding device (1) for producing wire netting (2) having longitudinal rods (3) and transverse rods (4). The resistance welding device (1) comprises: a first welding head (7) having a first welding electrode (8); a second welding head (9) having a second welding electrode (10). A contact electrode (18) is formed on the first welding head (7) and a current bridge (19) is formed on the second welding head (9), said current bridge being electrically conductively coupled to the second welding electrode (10), wherein the contact electrode (18) can be brought directly into contact with the current bridge (19), and wherein the longitudinal rod to be welded (3) and the transverse rod (4) can be clamped simultaneously between the first welding electrode (8) and the second welding electrode (10).

Description

Resistance welding device and method for producing wire nets

The invention relates to a resistance welding device for producing wire nets with longitudinal bars and transverse bars, and to a method for producing wire nets with longitudinal bars and transverse bars.

DE1107855B discloses a mesh welding machine having a first and a second welding head. At the first welding head, a current bridge is arranged. On the second

Welding head is arranged a first and a second welding electrode, wherein between the first welding electrode and the current bridge, a first longitudinal bar and a cross bar can be introduced and between the second welding electrode and the current bridge, a second longitudinal bar and the cross bar can be introduced. The first longitudinal bar and the second longitudinal bar are welded simultaneously with the transverse bar.

From AT292427B a grid welding machine is known, which has a first welding electrode, which is arranged on a first welding head and having a second welding electrode, which is arranged on a second welding head, wherein between the first welding electrode and the second welding electrode, a longitudinal bar and a cross bar can be brought to weld them together. The first welding head is coupled by means of consumers current-carrying with a first busbar. The second welding head is coupled by means of consumers energized with a second busbar.

Other mesh welding machines are known from EP0335858A2 and W002070168A1 be known.

The grid welding machine known from DE1107855B has the disadvantage that the amount of current at the first and at the second longitudinal bar can not be regulated independently of one another. Thus, it is not possible to ensure reliable welding of both longitudinal bars. In addition, it is not possible to weld two longitudinal bars with different thicknesses to the transverse bar, as this would lead to different welding depths. The mesh welding machine known from AT292427B has the disadvantage that the first welding head can only be displaced in the transverse direction if no longitudinal bar is inserted into the mesh welding machine.

Object of the present invention was to overcomes the disadvantages of the prior art and to provide an apparatus and a method available by means of the wire nets with longitudinal bars and transverse bars can be made flexible.

This object is achieved by an apparatus and a method according to the claims.

According to the invention, a resistance welding device for producing wire nets with longitudinal bars, which are parallel to a longitudinal direction of the resistance welding device can be introduced and transverse bars, which are parallel to a perpendicular to the longitudinal direction aligned transverse direction of the resistance welding device, formed. The resistance welding device comprises:

a first welding head having a first welding electrode;

a second welding head with a second welding electrode.

At the first welding head, a contact electrode is formed and at the second welding head, a current bridge is formed, which is electrically conductively coupled to the second welding electrode, wherein the contact electrode is directly brought into contact with the current bridge and wherein the longitudinal bars and cross bars to be welded simultaneously between the ers th Welding electrode and the second welding electrode are clamped.

The resistance welding device according to the invention has the advantage that the longitudinal rod and the cross bar are clamped between the first welding electrode and the second welding ßelektrode and thus the energy input for welding the longitudinal rod and the cross bar can be set exactly. The contact electrode is in this case electrically coupled to the current bridge, so that only at the first welding head, a power supply or power dissipation must be arranged and the second welding head, only the second current bridge can be arranged. Furthermore, it may be expedient if the first welding head, a transformer angeord net, which is electrically conductively coupled to the first welding electrode and the contact electrode rode. The advantage here is that the energy required for the welding process does not have to be supplied by a far away from the contact electrodes transformer by ei ner busbar, but that the lines which are arranged between the transformer and the welding electrode and thus have to conduct a high current , can be kept as short as possible. As a result, the energy loss at the resistance welding device can be kept as low as possible.

Furthermore, it can be provided that the first welding head is coupled to a first linear guide ge and is slidable along this and that the second welding head is coupled to a second linear guide and is slidable along this. The two linear guides are in this case aligned in the transverse direction of the resistance welding device, so that the two welding heads are ver pushed in the transverse direction of the resistance welding device. By this measure can be achieved that variously ausgebil finished wire nets can be welded together. In particular, the flexibility of the resistance welding device can thereby be increased.

In addition, it can be provided that at least two first welding heads are arranged on the first linear guide and at least two second welding heads are arranged on the second linear guide. The advantage here is that the individual pairs of welding heads can be operated parallel to each other and thus the production speed of the resistance welding device can be increased.

Also advantageous is an expression, according to which it can be provided that the current bridge has a contact element which is conical and that the Kontaktelek electrode is thus formed correspondingly hollow conical. By this measure, the contact surface between the contact element and the contact electrode can be increased, so that the power transmission between the contact element and the contact electrode can be improved ver.

According to a development, it is possible that the first welding electrode is coupled to a first actuator, in particular to a pneumatic cylinder, and in the direction of the second Welding electrode is displaceable. By this measure, the longitudinal bars and cross bars between the first welding electrode and the second welding electrode can be clamped.

Furthermore, it may be expedient if the contact electrode with a second actuator, in particular special with a pneumatic cylinder, coupled and is ver pushed in the direction of the current bridge. By this measure, the contact electrode abge lifted from the current bridge, so that the welding heads can be moved over already existing longitudinal bars away in the transverse direction of the resistance welding device.

In addition, it can be provided that the first actuator and the second actuator are independently operable. By this measure can be achieved that the contact electrode regardless of the welding electrode brought into contact with the current bridge who can to allow a current flow.

Furthermore, it can be provided that a first flexible current bridge is formed, by means of which the first welding electrode is coupled to the transformer. By this measure measure the welding electrode can be moved relative to the transformer.

According to a particular embodiment, it is possible that a second flexible current bridge is formed, by means of which the contact electrode is coupled to the transformer. By this measure, the contact electrode can be moved relative to the transformer.

According to an advantageous development, it can be provided that the current bridge is coupled to an adjusting device by means of which it is displaceable in the direction of the first welding electrode. By this measure, the current bridge can be adapted to differently designed wire nets.

In particular, it may be advantageous if the adjusting device comprises an eccentric, which is coupled to a drive unit, in particular a servomotor. Furthermore, it can be provided that the current bridge has a cooling channel in which a cooling medium can be guided. By this measure, the current bridge can be cooled, whereby the current-carrying properties of the current bridge can be improved.

In addition, it can be provided that the first welding electrode and the contact electrode of the first welding head are offset relative to one another in the transverse direction of the resistance welding device. It can thereby be achieved that the contact electrode between tween the individual longitudinal bars and transverse bars can be passed through and thus can be brought directly into contact with the current bridge.

The invention also provides a method for producing wire nets with longitudinal bars and transverse bars. The method comprises the following method steps:

- positioning a transverse bar relative to a longitudinal bar;

Positioning a first welding head and a second welding head in such a way that an overlapping region of the transverse rod and the longitudinal rod is arranged between a first welding electrode of the first welding head and a second welding electrode of the second welding head and that the contact electrode can be brought into direct contact with the current bridge, without touching a longitudinal bar or a transverse bar;

- Moving the contact electrode to the current bridge until the contact electrode is brought into contact with the current bridge;

- Moving the first welding electrode to the second welding electrode, so that the longitudinal rod and the cross bar between the first welding electrode and the second Schweißelekt are clamped rode;

- applying power to the welding electrodes so that the crossbar and the longitudinal bar are welded together;

- Distancing the two welding electrodes from each other, as well as the contact electrode of the current bridge.

An advantage of the method according to the invention is that by this method wire nets can be produced with increased flexibility. The term wire mesh is used for all structures having a grid structure with Längsstä ben and transverse bars. The longitudinal bars and cross bars can in this case be arranged in a belie bigen angle to each other and have any shape.

In a first embodiment, the wire mesh may be formed, for example, as a reinforcement mat, which serves as a reinforcement in concrete structures.

In a further embodiment, the wire mesh may be formed as a grid.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

In each case, in a highly simplified, schematic representation:

Fig. 1 is a perspective view of an embodiment of a resistor

welding device;

Fig. 2 is a perspective view of an embodiment of a first and a second welding head;

Fig. 3 is another perspective view of an embodiment of the first and the second welding head.

Introductoryly it should be noted that in the differently described embodiments, the same parts provided with the same reference numerals or the same component names who the, with the disclosures contained in the entire description mutatis mutandis to equivalent parts with the same reference numerals or the same component names who can. Also, the position information selected in the description, such as above, un th, laterally, etc. related to the immediately described and illustrated figure and these position information in a change in position mutatis mutandis to transfer to the new location. 1 shows a schematic representation of a resistance welding device 1 for making wire nets 2 with longitudinal bars 3 and transverse bars 4.

The longitudinal bars 3 are guided in the resistance welding device 1 such that they run pa rallel to a longitudinal direction 5 of the resistance welding device 1. The transverse bars 4 are guided in the resistance welding device 1 such that they run parallel to egg ner transverse direction 6 of the resistance welding device 1.

In particular, it can be provided that the longitudinal bars 3 and the transverse bars 4 of the wire nets 2 are arranged at right angles to each other.

In a preferred embodiment of the present embodiment, the wire mesh 2 is formed as a reinforcement mat. The longitudinal bars 3 and cross bars 4 are accordingly speaking as round material formed from a reinforcing steel. The longitudinal bars 3 and the cross bars 4 may in this case have different diameters. Furthermore, it is also conceivable that, for example, two mutually adjacent longitudinal bars 3 or two mutually adjacent transverse bars 4 have a different diameter. In a Favor th embodiment, it is provided that the cross bars 4 are all arranged on one side of the longitudinal bars 3 and welded by means of the resistance welding device 1 with the longitudinal bars 3.

The resistance welding device 1 has at least one first welding head 7 with a first welding electrode 8 and a second welding head 9 with a second welding β electrode 10.

As can be seen from FIG. 1, it can be provided that the resistance welding device 1 has a plurality of first welding heads 7 or a plurality of second welding heads 9. The first welding heads 7 are arranged on a first linear guide 11, by means of which the welding heads 7 in the transverse direction 6 of the resistance welding device 1 are displaceable. Similarly, the second welding heads 9 by means of the second linear guide 12 in Qu errichtung 6 of the resistance welding device 1 can be displaced. In particular, it can be provided that the first linear guide 11 has a first guide rail 13, which is arranged on the base frame 14. Each of the first welding heads 7 may be coupled to a first guide carriage 15, which cooperates with the first guide rail 13. In particular, it is provided in this case that the first guide carriage 15 are slidably received in the first guide rail 13.

Similarly, it may be provided that the second linear guide 12, a second guide rail 16 includes, which is also received on the base frame 14.

It is further provided that each of the first welding heads 7 and each of the second welding heads 9 is coupled to a drive unit, so that the welding heads 7, 9 can be moved or positioned in the transverse direction 6 of the resistance welding device 1. In the present exemplary embodiment, it is provided that each of the welding heads 7, 9 has its own drive unit and the welding heads 7, 9 can thus be moved or positioned independently of each other in the transverse direction 6 of the resistance welding device 1. In another embodiment, it may also be provided that in each case a first welding head 7 and an associated second welding head 9 are coupled to a common drive unit and thus are always adjustable in pairs to each other.

The drive unit for adjusting the welding heads 7, 9 may for example comprise an electric motor, which is arranged on the base frame 14 and ge coupled with a drive roller, which drives a circulating between the drive roller and a guide pulley timing belt. The toothed belt is in this case coupled to the welding head 7, 9.

In a further embodiment, it can also be provided that the drive unit is arranged directly on the welding heads 7, 9 and is coupled to a toothed wheel, which engages Ches in a arranged on the base frame 14 rack.

Of course, all other drive units known to those skilled in the art for positioning the welding heads 7, 9 can be used. In Figures 2 and 3, another and optionally independent Ausfüh tion form of the welding heads 7, 9 is shown, in turn, the same reference signs or component names are used as in the previous Fig. 1 for the same parts. In order to avoid unnecessary repetition, reference is made to the detailed description in the pre-GE Fig. 1 or reference.

In particular, Figures 2 and 3, an embodiment of the first welding head 7 and the associated second welding head 9 is shown in various perspective views, the further description of the welding heads 7, 9 based on an inspection together Fig. 2 and 3 takes place.

As can be seen from FIGS. 2 and 3, it is provided that the first welding head 7 has a contact electrode 18 in addition to the first welding electrode 8. The contact electrode 18 can be brought directly into contact with a current bridge 19, which is arranged on the second welding head 9 in con tact. In particular, it can be provided that a contact element 20 is arranged on the current bridge 19, with which the contact electrode 18 can be contacted. As can be seen from FIGS. 2 and 3, it can be provided that the second welding electrode 10 and the contact element 20 are arranged directly on the current bridge 19. As can be seen from Figs. 2 and 3, it can be provided that the first welding head 7 and the second welding head 9 are positioned to each other such that the first welding electrode 8 and the second welding electrode 10 are arranged opposite to each other and the contact electrode 18 and the Contact element 20 are arranged opposite to each other.

It is further provided that the first welding electrode 8 is gekop pelt with a first actuator 21 and that the contact electrode 18 is coupled to a second actuator 22. In particular, it can be provided that the first actuator 21 and the second actuator 22 are designed as hydraulic or pneumatic cylinders. The first welding electrode 8 may in this case be arranged on a piston rod of the first actuator 21 and the contact electrode 18 may be arranged directly on a piston rod of the second actuator 22. In the present embodiment example, it is provided that the first actuator 21 and the second actuator 22 independently of each other, the first welding electrode 8 and the contact electrode 18 can move in a feed direction 23. By displacement of the contact electrode 18 in the direction of adjustment 23, this can be combined with the contact element 20. By shifting the first Welding electrode 8, this can be combined with the second welding electrode 10 who the.

Furthermore, it can be provided that at the first welding head 7, a transformer 24 is angeord net, by means of which the welding current required for the resistance welding is provided. Thus, it can be provided that each of the first welding heads 7 has a eige NEN transformer 24 which is arranged directly on the welding head 7 and with the welding head 7 in the transverse direction 6 of the resistance welding device 1 is displaceable.

It is further provided that the first welding electrode 8 by means of a first flexible current bridge 25 is coupled to the transformer 24. By this measure, the first welding electrode 8 can be moved relative to the transformer 24 in the feed direction 23.

It is further provided that the contact electrode 18 is coupled by means of a second flexible current bridge 26 to the transformer 24. By this measure, the contact electrode 18 can be moved in the direction of adjustment 23 relative to the transformer 24. By means of the first flexible current bridge 25 or the second flexible current bridge 26, the first welding electrode 8 and the contact electrode 18 are electrically conductively coupled to the transformer 24. In particular, it is provided that the flexible current bridges 25, 26 have a large conductor cross-section in order to transmit the necessary for a resistance welding high currents can. The flexible current bridges 25, 26 may in this case have a composite of several individual plates or films structure, wel che the current bridges 25, 26 are flexible. In particular, it can be provided that the flexible current bridges 25, 26 are formed from a copper material.

Furthermore, it can be provided that the current bridge 19 of the second welding head 9 is coupled with egg ner adjusting device 27, by means of which the current bridge 19 in Zustellrich device 23 is slidably disposed on the second welding head 9. The Ver adjusting device 27 may include an eccentric 28 which is coupled to a drive unit 29 which serves to rotate the eccentric 28. By the rotational movement of the eccentric 28 by means of the drive unit 29, the displacement in the feed direction 23 can be achieved. At the drive unit 29 may preferably be in the form of an electric motor, in particular a servo motor. A servomotor has the advantage that an exact delivery the current bridge 19 is made possible or that the position of the current bridge 19 can be exactly be true.

Furthermore, it can be provided that the current bridge 19 of the second welding head 9 is arranged electrically isolated on the second welding head 9, so that it has no conductive connec tion with another component of the second welding head 9.

Furthermore, it can be provided that the current bridge 19 has a cooling channel 30, which serves to guide a cooling medium, whereby the current bridge 19 can be cooled. Coolant connections 31, by means of which the cooling medium can be introduced into the cooling channel 30, can be connected to the cooling channel 30. As the cooling medium, a fluid such as a liquid, a gas or an aerosol may be used.

Of course, a cooling channel can also be formed in the area of the first welding electrode 8 and the contact electrode 18. This cooling channel may also be formed in the power supply lines to the first welding electrode 8 and the contact electrode 18.

Furthermore, it can also be provided that a cooling channel is formed in the transformer 24.

As further seen in FIGS. 2 and 3, the first welding electrode 8 and the contact electrode 18 are spaced from each other at a transverse pitch 32 and at a longitudinal pitch 33. Correspondingly, the second welding electrode 10 and the contact element 20 in a transverse direction spacing 32 and in a Längsrichtungsab stood 33 spaced from each other. By this measure it can be achieved that an overlap 34 of the longitudinal bar 3 and the transverse bar 4 between the first Schweißelekt rode 8 and the second welding electrode 10 can be placed and at the same time between the contact electrode 18 and the contact element 20, neither a longitudinal bar 3 nor a transverse bar 4 are arranged. The transverse direction spacing 32 and the longitudinal spacing 33 be between 10 mm and 250 mm, in particular between 20 mm and 70 mm.

Based on a synopsis of Figs. 2 and 3, the procedure for producing egg ner resistance welding connection between a longitudinal bar 3 and a cross bar 4 be written. In a first method step, the entire wire mesh 2 is positioned in the resistance welding device 1 such that the transverse bar 4 to be welded is at the same height as the first welding electrode 8 and the second welding electrode 10. At the same time or in an upstream or subsequent process step, the first welding head 7 and the second welding head 9 are displaced in the transverse direction 6, so that the overlap 34 of the longitudinal bar 3 and the transverse bar 4 is arranged exactly between the first welding electrode 8 and the second welding electrode 10 , This positioning situation is shown in FIG.

In a subsequent method step, the contact electrode 18 is moved by means of the second actuator 22 in the feed direction 23 to the contact element 20 until the contact electrode 18 and the contact element 20 touch each other. Thereby, a current-conducting connec tion between the contact electrode 18 and the contact element 20 can be made. At closing or at the same time, the first welding electrode 8 can be moved in the direction of adjustment 23 for two th welding electrode 10 until the longitudinal bars to be welded 3 and transverse bars 4 between the first welding electrode 8 and the second welding electrode 10 ge be clamped. Here, the longitudinal bar 3 at the first welding electrode 8 and the transverse bar 4 abut the second welding electrode 10. Of course, it can also be provided that the transverse bar 4 rest against the first welding electrode 8 and the longitudinal bar 3 at the two-th welding electrode 10.

For welding the transverse bar 4 with the longitudinal bar 3, the first welding electrode 8 is pressed at a predetermined pressure in the direction of the second welding electrode 10, so that the longitudinal bar 3 and the transverse bar 4 are pressed ge against each other with a predefined pressure. By introducing a predetermined amount of current in the first welding ßelektrode 8 and in the contact electrode 18 in this case the longitudinal rod 3 and the transverse rod 4 are heated due to their electrical resistance. The contact electrode 18 provides here with the second welding electrode 10 a direct electrical line forth, so that from going from the transformer 24 can form a closed circuit, excluding Lich the first welding electrode 8 and the second welding electrode 10 are spaced from each other and the components to be welded between the first welding electrode 8 and the second welding electrode 10 are arranged. Thus, the device 1 Widerstandsschweißvorrich be operated as efficiently and energy efficient.

After staying in this state in a predetermined welding time, the welding current is switched off again and the first welding electrode 8 and the contact electrode 18 are removed from the current bridge 19. Subsequently, the two welding heads 7, 9 can be repositioned in the transverse direction 6 and / or in the longitudinal direction 5, so that a further longitudinal bar and another transverse bar 4 or the same longitudinal bar 3 with a white direct transverse bar 4 or the same cross bar 4 with a further longitudinal bar 3 can be welded.

The embodiments show possible embodiments, it being noted at this point be that the invention is not limited to the specifically illustrated embodiments dersel ben, but also various combinations of the individual Ausfüh insurance variants are mutually possible and this variation possibility due to the teaching of technical action representational invention in the skill of those skilled in this technical field.

The scope of protection is determined by the claims. However, the description and drawings are to be considered to interpret the claims. Individual features or feature combinations from the illustrated and described different Ausführungsbeispie len can represent for themselves inventive solutions. The independent inventive solutions underlying task can the description taken from who the.

All information on ranges of values in objective description should be understood to include these arbitrary and all sub-ranges thereof, eg the indication 1 to 10 should be understood as including all sub-ranges, starting from the lower limit 1 and the upper limit 10 are, ie all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, eg 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10. For the sake of order, it should finally be pointed out that, for a better understanding of the structure, elements have been partially rendered out of scale and / or enlarged and / or reduced Darge.

Reference numeral 11 Resistance welding device 31 Coolant connection Wire mesh 32 Transverse direction Distance from longitudinal bar 33 Longitudinal distance Transverse bar 34 Overlap

longitudinal direction

transversely

first welding head

first welding electrode

second welding head

second welding electrode

first linear guide

second linear guide

first guide rail

base frame

first guide carriage

second guide rail

second guide carriage

contact electrode

current bridge

contact element

first actor

second actor

To adjustment direction

transformer

first flexible power bridge

second flexible power bridge

Ver adjusting device

eccentric

drive unit

cooling channel

Claims

Patent claims

1. Resistance welding device (1) for producing wire nets (2) with longitudinal bars (3) which are parallel to a longitudinal direction (5) of the Widerstandsschweißvorrich device (1) can be introduced and transverse bars (4) which at an angle thereto in the transverse direction (6) the resistance welding device (1) can be introduced, the resistance welding device (1) comprising:

a first welding head (7) having a first welding electrode (8);

a second welding head (9) with a second welding electrode (10),

characterized in that at the first welding head (7) forms a contact electrode (18) out and on the second welding head (9) a current bridge (19) is formed, which is electrically conductively coupled to the second welding electrode (10), wherein the contact electrode (18) directly to the current bridge (19) can be brought into contact and wherein the ver welded longitudinal bar (3) and transverse bar (4) at the same time between the first Schweißelekt rode (8) and the second welding electrode (10) are clamped.

2. Resistance welding device according to claim 1, characterized in that at the first welding head (7), a transformer (24) is arranged, which is electrically conductively coupled to the first welding electrode (8) and to the contact electrode (18).

3. Resistance welding device according to claim 1 or 2, characterized in that the first welding head (7) with a first linear guide (11) is coupled and ent long is slidable and that the second welding head (9) tion with a second Linearfüh (12 ) and is slidable along this.

4. Resistance welding device according to claim 3, characterized in that at least two first welding heads (7) are arranged on the first linear guide (11) and at least two second welding heads (7) are arranged on the second linear guide (12).

5. Resistance welding device according to one of the preceding claims, characterized in that the current bridge (19) has a contact element (20) wel Ches is formed conically and that the contact electrode (18) is formed correspondingly hollow conical.

6. Resistance welding device according to one of the preceding claims, characterized in that the first welding electrode (8) with a first actuator (21), in particular with a pneumatic cylinder, coupled and in the direction of the second welding ßelektrode (10) is displaceable.

7. Resistance welding device according to one of the preceding claims, characterized in that the contact electrode (18) with a second actuator (22), in particular special with a pneumatic cylinder, is coupled and in the direction of the current bridge (19) is displaceable.

8. Resistance welding device according to claim 7, characterized in that the first actuator (21) and the second actuator (22) are actuated independently of each other.

9. Resistance welding device according to one of claims 2 to 8, characterized in that a first flexible current bridge (25) is formed, by means of which the first welding electrode (8) to the transformer (24) is coupled.

10. Resistance welding device according to one of claims 2 to 9, characterized in that a second flexible current bridge (26) is formed, by means of which the contact electrode (18) is coupled to the transformer (24).

11. Resistance welding device according to one of the preceding claims, characterized in that the current bridge (19) with an adjusting device (27) gekop pelt, by means of which it is displaceable in the direction of the first welding electrode (8).

12. Resistance welding device according to claim 11, characterized in that the adjusting device (27) comprises an eccentric (28), which is coupled to a drive unit (29), in particular a servomotor.

13. Resistance welding device according to one of the preceding claims, characterized in that the current bridge (19) has a cooling channel (30) in wel chem a cooling medium is feasible.

14. Resistance welding device according to one of claims 3 to 13, characterized in that the first welding electrode (8) and the contact electrode (18) of the first welding head (7) in the transverse direction (6) of the resistance welding device (1) are arranged offset to each other ,

15. A method for producing wire nets (2) with longitudinal axes (3) and transverse bars (4), in particular using a resistance welding device (1) according to ei nem of the preceding claims, characterized in that the method steps follow the method steps includes:

- positioning a transverse bar (4) relative to a longitudinal bar (3);

- Positioning a first welding head (7) and a second welding head (9) such that an overlapping region of the transverse rod (4) and the longitudinal rod (3) between a first welding electrode (8) of the first welding head (7) and a second Schweißelekt rode ( 10) of the second welding head (9) and that the contact electrode (18) can be brought into direct contact with the current bridge (19) without touching a longitudinal bar (3) or a transverse bar (4);

- Moving the contact electrode (18) to the current bridge (19) until the contact electrode (18) is brought into contact with the current bridge (19);

- moving the first welding electrode (8) to the second welding electrode (10) so that the longitudinal bar (3) and the transverse bar (4) are clamped between the first welding electrode (8) and the second welding electrode (10);

- Applying current to the welding electrodes (8, 10), so that the transverse rod (4) and the longitudinal bar (3) are welded together;

- Distancing the two welding electrodes (8, 10) from each other, and the contact electrode (18) from the current bridge (19).