CN112530684A

CN112530684A - Welding transformer, method for producing the same, and method for producing module of welding transformer

Info

Publication number: CN112530684A
Application number: CN202010986580.1A
Authority: CN
Inventors: D·里塔尔西克
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-09-19
Filing date: 2020-09-18
Publication date: 2021-03-19
Also published as: EP3796345A1

Abstract

The invention relates to a welding transformer, a method for producing the same, and a method for producing a module of the welding transformer. A welding transformer, a method for producing a module for a welding transformer and a method for producing a welding transformer are provided. The welding transformer includes: a core; at least one primary winding wound around the core such that the at least one primary winding is connectable with a power source to supply a primary voltage to the at least one primary winding; and at least two modules, wherein each of the at least two modules is formed as one part comprising at least one secondary winding wound around the core such that the at least one secondary winding is capable of converting the primary voltage to a secondary voltage for supplying a welding current to the welding tool; and a mounting unit for mounting a rectifier to a welding transformer to rectify a secondary voltage to supply a direct current as a welding current to the welding tool.

Description

Welding transformer, method for producing the same, and method for producing module of welding transformer

Technical Field

The invention relates to a welding transformer, a method for producing a module for a welding transformer and a method for producing a welding transformer.

Background

The welding transformer is used by a welding tool to provide a predetermined current to join metal components of an article through at least one weld. To create the weld, the welding tool may be guided by hand or by a robot. Transformers are often attached to the welding tool to omit bulky high voltage cables. In this case, the weight and size of the transformer need to be optimized to facilitate handling of the bonding tool. This also contributes to keeping the power consumption of the bonding tool low.

Such lightweight welding transformers are typically connected to rectifiers. The transformer converts the primary alternating current to a secondary alternating current having desired intensity and time characteristics. The secondary side of the transformer is connected to a rectifier that rectifies the current output from the transformer and provides a direct current to at least one welding electrode of the welding tool. A weld seam can be produced if a welding electrode is brought into contact with a metal component and a corresponding welding current is fed to the welding electrode.

One problem is that the current generated by the transformer-rectifier unit generates a large amount of heat. This requires, for example, cooling of the transformer-rectifier unit by means of water as coolant. Because of this, the transformer and rectifier are usually made of a number of different parts to allow cooling of the unit and compact size of the unit.

Another problem is that a plurality of different parts will be connected such that sufficient stability is achieved to allow safe operation for moving the welding tool around. In this context, brazing is required, which leads to oxidation of the soldered parts. Therefore, the part must be laboriously cleaned.

All this makes the assembly of the transformer-rectifier unit rather complicated. Therefore, the transformer-rectifier unit is expensive.

Disclosure of Invention

It is therefore an object of the present invention to provide a welding transformer, a method for producing a module for a welding transformer and a method for producing a welding transformer, which are capable of solving the above-mentioned problems. In particular, it is an object of the present invention to provide a welding transformer, a method for producing a module for a welding transformer and a method for producing a welding transformer, which enable to simplify and enhance the assembly of a transformer-rectifier unit, such that a lightweight transformer-rectifier unit can be built with high stability and low cost.

This object is solved by a welding transformer for a welding tool according to the features of claim 1. The welding transformer includes: a magnetic core; at least one primary winding wound around the core such that the at least one primary winding is connectable with a power source to supply a primary voltage to the at least one primary winding; and at least two modules, wherein each of the at least two modules is formed as one part comprising at least one secondary winding wound around a core such that the at least one secondary winding is capable of converting a primary voltage to a secondary voltage for supplying a welding current to a welding tool; and a mounting unit for mounting the rectifier to the welding transformer for rectifying the secondary voltage for providing the direct current as a welding current to the welding tool.

In the described welding transformer, the number of metal parts or modules is reduced to a minimum, since there is no separate secondary winding and separate rectifier mounting unit.

A further advantage of the described welding transformer is that brazing is no longer required. The module is constructed such that the joint can be formed with other parts of the transformer only by fastening elements, such as screws. Due to the reduced number of components, only a small number of joints with the fastening element are produced. Due to this, the construction of the transformer-rectifier unit is more stable than a transformer-rectifier unit with more parts, and therefore more joints with fastening elements are required. This also results in better efficiency due to reduced current consumption.

Thus, the welding transformer described above is constructed such that the assembly of the individual components or modules of the welding transformer is easier than a transformer with a separate secondary winding and a separate rectifier mounting unit.

Further advantageous developments of the welding transformer are stated in the dependent claims.

Possibly, each of the at least two modules comprises a cooling liquid channel.

According to one configuration, the coolant channel comprises an opening for the inlet and/or outlet of the coolant, wherein the opening is positioned between the at least one secondary winding and the mounting unit.

According to another configuration, each of the at least two modules comprises at least one blind hole and at least one through hole that cross each other to form a coolant channel. Herein, at least one of the openings includes a thread for sealing the coolant passage to the outside using a screw stopper.

The form of the secondary winding of one module may be different from the form of the mounting unit of the module.

In an advantageous configuration, the secondary winding of one of the modules is connected with the mounting unit of the module via a connector, which is positioned off the centre line of the module.

It is conceivable that the welding transformer comprises a first module and a second module having the same external form and/or shape, wherein the first and second modules are positioned spaced apart from each other and side by side such that the connector of the first module is positioned on the other side of the midline of the first module than the connector of the second module.

Possibly, at least two modules are made of copper or aluminum.

In a particular configuration, each of the at least two modules is coated with a coating that protects the module from corrosion.

The welding transformer described above may be part of a welding tool for producing an article. The welding tool may further comprise a control unit configured to adjust the welding current for forming the article by joining at least two parts and/or at least two parts of one part by at least one weld joint. In this context, the welding tool may further comprise means for moving the welding tool along the at least one component according to a predetermined movement profile, wherein the article is a vehicle body.

The above-mentioned object is further solved by a method for producing a module for a welding transformer according to the features of claim 13. The method comprises the following steps: forming a plate-shaped module such that the module includes a secondary winding and a mounting unit for mounting the rectifier to the welding transformer; and machining the at least one blind hole and the at least one through hole into a module such that the openings intersect each other to form a coolant channel in the module.

This method achieves the same advantages as mentioned above in connection with the welding transformer.

The above-mentioned object is further solved by a method for producing a welding transformer according to the features of claim 14. The method comprises the following steps: positioning a first module laterally inverted to a second module, wherein the first and second modules have at least the same external form, wherein each module comprises a secondary winding and a mounting unit for mounting the rectifier to the welding transformer, and wherein the first and second modules are positioned such that the secondary windings of the first and second modules are positioned facing each other, positioning and fastening at least two semiconductor modules between the mounting units of the first and second modules to build a stack, wherein the at least two semiconductor modules are positioned on both sides of a central module of the rectifier in the stack.

The method may further comprise the steps of: the core of the transformer is mounted into the recess of the secondary windings of the at least two semiconductor modules.

Even if not explicitly mentioned, further possible embodiments of the invention also comprise combinations of features or patterns described above or below with reference to the examples. In this context, the person skilled in the art will also add individual aspects as modifications or additions to the respective basic forms of the invention.

Further embodiments of the invention are the subject of the examples of the invention described below.

Drawings

The invention is described in more detail hereinafter by means of embodiments and with reference to the accompanying drawings, in which:

fig. 1 schematically shows a block diagram of an apparatus (plant) with a welding device according to an embodiment;

FIG. 2 illustrates a three-dimensional view of a raw module of a welding transformer for a welding device, according to an embodiment;

FIG. 3 shows a plan view of a first module implemented after the openings for cooling channels and for mounting machined in the module of FIG. 2;

FIG. 4 shows a plan view of a second module implemented after the openings for cooling channels and for mounting machined in the module of FIG. 2;

FIG. 5 shows a side view of the assembly of the symmetrically positioned first and second modules of FIGS. 3 and 4;

fig. 6 shows a first side view of the module of fig. 5 with a component or assembly of modules of a rectifier;

fig. 7 shows a second side view of the module of fig. 5 in combination with a component or assembly of modules of a rectifier;

fig. 8 shows a bottom view of the module of fig. 5 with components or assemblies of modules of a rectifier;

fig. 9 shows a flow diagram to illustrate a method for producing a module for a welding transformer; and

fig. 10 shows a flow chart for illustrating a method for producing a welding transformer.

In the drawings, identical or functionally identical elements are provided with the same reference signs, unless otherwise indicated.

Detailed Description

Fig. 1 very schematically shows an apparatus 1 with a welding device 2. Specifically, the welding device 2 is a resistance welding device. The apparatus 1 is a production apparatus for producing articles such as vehicles, home appliances, heaters, and the like.

In the device 1, the metal parts 5, 6 can be connected such that a welded joint 7 is produced. For this purpose, the welding device 2 comprises a welding tool 10. The welding tool 10 is formed as a welding gun comprising two

welding electrodes

11, 12, a control unit 20, a welding transformer 30 and a rectifier 40. In the example of fig. 1, the bonding tool 10 is moved by the apparatus 50. The device 50 may be a robot.

The welding device 2 can generate the weld joint 7 by means of the welding tool 10 for control of the control device 20. In this context, for example, two edges of a single component 5 can be connected by one or more weld joints 7. Regardless of the number of components 5, 6 connected by the weld joint 7, the weld joint(s) may be produced by at least one weld spot or at least one weld seam or a combination of both.

The welding transformer 30 is mounted to the rectifier 40 such that a transformer-rectifier unit is provided.

The welding transformer 30 has a primary winding 31 and a secondary winding 32 both positioned at a common core 33. The primary winding 31 is connected to a power supply 25, which power supply 25 provides the necessary power and voltage U1 for welding, as shown by the left arrow in fig. 1. The secondary winding 32 has three

outputs

35, 36, 37 such that a first primary voltage U21 and a second secondary voltage U22 are generated. The first primary voltage U21 and the second secondary voltage U22 form a welding voltage U23, which welding voltage U23 leads to a welding current I2 at the output of the transformer-rectifier unit. In the example shown, the welding transformer 30 is a medium frequency direct current transformer (MF-DC transformer).

In the example of fig. 1, the rectifier 40 has first to fourth semiconductor devices 41 to 44, for example, transistors 41 to 44. The first semiconductor arrangement 41 is connected to the first output 35 of the welding transformer 30. The second semiconductor device 42 is connected in series to the first semiconductor device 41. Thus, the series connection of the first and

second semiconductor devices

41, 42 is connected between the transformer 30 and the bonding tool 10. In more detail, the series connection of the first and second semiconductor arrangement is connected between the secondary winding 32 of the transformer 30 and the first welding electrode 11.

The second welding electrode 12 is connected to a second output 36 of the transformer 30.

The third semiconductor arrangement 43 is connected to the third output terminal 37 of the transformer 30. The fourth semiconductor device 44 is connected in series to the third semiconductor device 43. Thus, the series connection of the third and

fourth semiconductor devices

43, 44 is connected between the transformer 30 and the bonding tool 10. In more detail, the series connection of the third and

fourth semiconductor arrangement

43, 44 is connected between the secondary winding 32 of the transformer 30 and the first welding electrode 11.

In the case where the semiconductor devices 41 to 44 are four transistors, the transistors 41 to 44 are switched under the control of the control unit 20 to switch the polarity of the welding voltage U23. Alternatively, the

semiconductor devices

41, 42 may be replaced by one diode, and the

semiconductor devices

43, 44 may be replaced by another diode to provide a direct current as the welding current I2.

Fig. 2 shows a primitive module 34 configured to connect a transformer 30 and a rectifier 40. The primitive modules 34 are formed of one piece. The component is made of metal, in particular copper or aluminium or at least one other metal capable of conducting electricity. Copper and aluminum are advantageous in their relatively small electrical resistance and high thermal conductivity.

Possibly, the module 34 is coated with a coating 340, as shown only very schematically in fig. 2. The coating 340 can protect the

modules

3401, 3402 from corrosion. For example, the coating 340 may be a coating for passivating aluminum or an aluminum alloy, in particular the coating may be anodized. Alternatively, the coating 340 may be an electrocoat. Alternatively, the coating 340 may be a chemical coating of nickel. Alternatively, the coating 340 may be a cathodic dip coating. Alternatively, the coating 340 may be a plastic coating. Alternatively or additionally, the coolant may include a corrosion inhibitor.

The primitive modules 34 have a plate-like form. The primary module 34 has a secondary winding 341, a mounting unit 342, a connector 343, a recess 344, a first gap 345 and a second gap 346. The outer edges of the primitive modules 34 may be rounded.

The secondary winding 341 has a first end 3411 and a second end 3412.

The secondary winding 341 is wound around the recess 344, in which the core 33 of the transformer 30 is to be inserted. In the example of fig. 2, the outer edges of the secondary winding 341 are slanted. Further, in the example of fig. 2, the recess 344 has an approximately square cross-section. The first end 3411 of the secondary winding 341 is connected to the mounting unit 342 through a connector 343. The second end 3412 is a free end of the secondary winding 341. Herein, the second end 3412 protrudes from the secondary winding 341 in the direction of the mounting unit 342. The second end 3412 is positioned facing the mounting unit 342. The second end 3412 is positioned spaced apart from the mounting unit 342 by a first gap 345. Thus, the first gap 345 separates the second end 3412 and the mounting unit 342.

In the example of fig. 2, the mounting unit 342 has an approximately rectangular cross section. The mounting unit 342 is connected to a connector 343 at one of its four corners. Connector 343 is positioned off center line M of module 34. The midline M is approximately orthogonal to the axis of the recess 344.

In the example of fig. 2, the connector 343 has an approximately rectangular cross-section. Herein, the long side of the rectangular connector 343 is positioned to be transverse to the long side of the mounting unit 342.

The first gap 345 is defined on one side by a portion of the long side of the mounting unit 342.

The connector 343 is positioned at least partially alongside the second end 3412. The second end 3412 is positioned spaced apart from the connector 343 by a second gap 346. Thus, the second gap 346 separates the second end 3412 from the connector 343. In the example of fig. 2, the second gap 346 is cascaded (cascade). Thus, the first ends 3412 of the secondary windings 341 are also cascaded.

The second gap 346 is bounded on one side by a portion of the long side of the connector 343 and a portion of the secondary winding 341. A second gap 346 separates the connector 343 and the first end 3411 of the secondary winding 341. Further, a second gap 346 separates the first and

second ends

3411, 3412 of the secondary winding 341.

The first gap 345 and the second gap 346 are connected to each other such that the

gaps

345, 346 have an approximately angular or L-shape. The

gaps

345, 346 are to be filled with an electrically insulating material. In fig. 2, the electrically insulating material is air, such that the

gaps

345, 346 are air gaps.

Fig. 3 shows a plan view of a first module 3401, the first module 3401 being produced starting from the original module 34 of fig. 2 by machining first and second

cooling channel openings

347, 348 for cooling channels into the original module 34 of fig. 2. Machining may be performed by drilling as

openings

347, 348.

The first opening 347 is a blind hole. The second opening 348 is a through hole. At least one of the openings 347 is provided with threads 3471 at its open end. Also, the opening 348 is provided with threads 3481 at each of the open ends thereof. Additionally, a third opening 349 is provided in the mounting plate 342 for mounting the rectifier 40 and the module 34 to each other. At least one of the openings 349 is provided with threads 3491 at its open end.

The

openings

347, 348 of the first module 3401 are positioned transverse to one another such that at least two of the

openings

347, 348 intersect one another. Thus, cooling channels are constructed by module 3401.

Fig. 4 shows a plan view of a second module 3402, which second module 3402 is produced starting from another original module 34 shown in fig. 2 by machining first and second

cooling channel openings

347, 348 for cooling channels into this original module 34 of fig. 2. As in module 3401 in fig. 3, first opening 347 of module 3402 in fig. 4 is a blind hole. The second opening 348 is a through hole. At least one of the openings 347 is provided with threads 3471 at its open end. Also, the opening 348 is provided with threads 3481 at each of the open ends thereof. Additionally, a third opening 349 is provided in the mounting plate 342 for mounting the rectifier 40 and the module 34 to each other. At least one of the openings 349 is provided with threads 3491 at its open end.

The

openings

347, 348 of the second module 3402 are positioned transverse to one another such that at least two of the

openings

347, 348 intersect one another. Thus, cooling channels are constructed by module 3402.

Thus, the first and

second modules

3401, 3402 have the same external form and/or shape. However, as can be taken from fig. 3 and 4, the

openings

347, 348 for the cooling channels can be different for the first and

second modules

3401, 3402.

To assemble the transformer 30 and the rectifier 40, the

modules

3401, 3402 are positioned with one another as shown in fig. 5.

As may be taken from fig. 5, the first and

second modules

3401, 3402 are positioned spaced apart from each other and side by side. In combination with fig. 2 to 4, it is apparent from fig. 5 that the connectors of the first module 3401 are positioned on the other side of the midline M of the first module 3401 than the connectors 343 of the second module 3402.

In other words, as shown in fig. 5,

modules

3401, 3402 are positioned to be symmetrical to each other, but laterally inverted from each other in transformer 30. In still other words, the first and

second modules

3401, 3402 are rotated about 180 ° from each other, i.e., about the centerline M of one of the

modules

3401, 3402 shown in fig. 2. Thus, the windings 341 of the

modules

3401, 3402 face each other. Also, the mounting units 342 of the

modules

3401, 3402 face each other. However, the connectors 343 of the

modules

3401, 3402 are positioned on two different sides of the stack constructed by the

modules

3401, 3402.

According to fig. 6 to 8, the rectifier 40 and the

modules

3401, 3402 may be installed as one unit. In this unit, the

openings

347, 348 are sealed by seals 3405 or plugs 3473. Thus,

openings

347, 348 are closed off so that no coolant can leak from

modules

3401, 3402. Thus, coolant may be circulated in the

modules

3401, 3402 to perform heat dissipation from the unit constructed by the transformer 30 and the rectifier 40. The coolant may be any suitable coolant, for example, a fluid and/or a gas, in particular water or oil or air.

As shown in fig. 6, the rectifier 40 includes a contact unit 45 for connection to a positive electrode and a contact unit 46 for connection to a negative electrode. The

contact unit

45, 46 is configured to deliver a welding current I2 to the

welding electrode

11, 12.

The rectifier 40 further comprises a first soldered semiconductor module 401, a second soldered semiconductor module 402, a central rectifier module 403, a first spring package module 404, a second spring package module 405 and a fastening device 408 having ends 409. As in fig. 6-8, modules 401-405 are stacked with

modules

3401, 3402. The stack built up by modules 401 to 405 and

modules

3401, 3402 is fastened with fastening means 408. For this purpose, the fastening means 408 are inserted through the openings 349 in all modules 401 to 405, 3401, 3402. Here, the

spring package modules

404, 405 perform a spring force to provide a pressure or holding force that holds the stack built by the modules 401 to 405 together.

The first soldering semiconductor module 401 is positioned between the first module 3401 and the center plate 403. The first bonding semiconductor module 401 may include the

semiconductor devices

41, 42 of the circuit shown in fig. 1. Alternatively, the semiconductor module 401 includes a diode for rectifying the voltage U21 shown in fig. 1.

The second soldered semiconductor module 402 is positioned between the second module 3402 and the center plate 403. The second soldered semiconductor module 402 may include transistors as the

semiconductor devices

43, 44 of the circuit shown in fig. 1. Alternatively, the semiconductor module 402 includes a diode for rectifying the voltage U22 shown in fig. 1.

The first spring package module 404 is positioned spaced apart from the first soldered semiconductor module 401. The second spring package module 405 is positioned spaced apart from the second soldered semiconductor module 402. Thus, the stack of rectifiers 40 comprises in this order a first spring package module 404, a first module 3401, a first soldered semiconductor module 401, a central rectifier module 403, a second soldered semiconductor module 402, a second module 3402 and a second spring package module 405.

As shown in fig. 7, the cooling channels created by

openings

347, 348 in

modules

3401, 3402 of fig. 3 and 4 are sealed to the exterior of

modules

3401, 3402 by seals 3405. The opening 347 provided with the seal 3405 may be used as an inlet or an outlet of the coolant passage. Each of the seals 3405 is used to seal the corresponding winding 341 so that the coolant is prevented from leaking from the coolant passage. An opening 347 with a seal 3405 is positioned between the at least one secondary winding 341 and the mounting unit 342. An opening 347 having a seal 3405 is positioned in the second end 3412 of the secondary winding 341.

The contact unit 46 for connecting to the negative electrode is configured to be connected to the cooling channel at an opening 347, the opening 347 being sealed by a seal 3405 shown in fig. 5 and 7.

In addition to fig. 6 and 7, fig. 8 also shows a fastening device 410 for fastening the contact unit 46 to the rectifier 40.

Fig. 9 very schematically illustrates a method for producing the module 3401 shown in fig. 3 or the module 3402 shown in fig. 4.

The method has a step S1 in which the original module 34 is integrally constructed. Herein, the raw material is formed such that, as shown in fig. 2, the raw module 34 has a winding 341, a mounting unit 342, a connector 343, recesses, and

gaps

345, 346. The raw module 34 may be constructed by cutting the windings 341, mounting units 342, connectors 343, recesses and

gaps

345, 346 from raw material, as shown in fig. 2. The cutting may be performed by a laser or as a water cut. Alternatively, the original module 34 may be constructed by molding or three-dimensional printing. The original module 34 may also be provided with a coating 340. Thereafter, the flow further proceeds to step S2.

In step S2, the

openings

347, 348, 349 are machined. The machining of the

openings

347, 348, 349 may be performed with a drill. At least a portion of the

openings

347, 348, 349 may be etched. Optionally, after machining the

openings

347, 348, 349, the raw module 34 may be provided with a coating 340. In this case, the

openings

347, 348, 349 may also be protected from corrosion. Thereafter, the flow further proceeds to step S3.

In step S3, the

threads

3471, 3481, 3491 of the

openings

347, 348 are machined. The machining of the

openings

347, 348 may be performed with a threaded cutting tool. Optionally, after machining the

threads

3471, 3481, 3491 of the

openings

347, 348, 349, the raw module 34 may be provided with the coating 340. In this case, the

openings

347, 348, 349 completed with the

threads

3471, 3481, 3491 can also be protected against corrosion. Thereafter, the flow further proceeds to step S4.

In step S4, the plug 3473 may be fastened (in particular screwed) into the

threads

3471, 3481 of the

openings

347, 348 for the coolant channels. Further, seals 3405 may be inserted into the openings 347 of the

respective modules

3401, 3402 to provide an inlet or an outlet for the coolant channels. Thereafter, the method ends.

Steps S1 to S4 may be performed for at least two

modules

3401, 3402 to construct the transformer-rectifier unit shown in fig. 6 to 8. Herein, steps S1 to S4 may be performed at least partially simultaneously.

Fig. 10 very schematically illustrates a method for producing a transformer 30, as described above with reference to fig. 5 to 8.

The method has a step S11 in which at least one of the

modules

3401, 3402 is set. The term "set up" includes at least one of the

modules

3401, 3402 produced as described above with reference to fig. 9. Thereafter, the flow further proceeds to step S12.

In step S12, at least two

modules

3401, 3402 are assembled with the modules 401 to 405 of the rectifier 40 in a stack, as shown in fig. 6. That is, the stack of the rectifier 40 is stacked such that the first spring package module 404, the first module 3401, the first soldered semiconductor module 401, the central rectifier module 403, the second soldered semiconductor module 402, the second module 3402, and the second spring package module 405 are positioned adjacent to each other in this order. Herein, the external form and/or shape of the first and

second modules

3401, 3402 are at least the same. The first and

second modules

3401, 3402 are rotated 180 ° from each other such that the windings 341 of the first and

second modules

3401, 3402 face each other and the mounting units 342 of the first and

second modules

3401, 3402 face each other. The stack is fastened by fastening elements 408, which fastening elements 408 are inserted and fastened into the third openings 349 of the modules 401 to 405, 3401, 3402. Thereafter, the flow further proceeds to step S13.

In step S13, the contact unit 45 for connection to the positive electrode and the contact unit 46 for connection to the negative electrode are mounted to the stack constructed in step S12. This can also be made with screws. Thereafter, the flow further proceeds to step S14.

In step S14, the secondary winding 341 is mounted on the core 33 of the transformer 30. For this, the core 33 is inserted into the recess 344 of the secondary winding 341. Further, at least one primary winding 31 is mounted on the core 33. Thereafter, the flow further proceeds to step S15.

In step S15, at least the secondary winding 341 is molded with resin (particularly, epoxy resin). Thereafter, the method ends.

Steps S11-S14 may be performed at least partially simultaneously. Additionally or alternatively, steps S11-S14 may be performed, at least in part, in a changed order.

Thus, a low-cost welding transformer 30 can be constructed without brazing. The welding transformer 30 has a minimum of individual parts and is very stable in construction.

According to a second embodiment, the module 34 of fig. 2 is further cut in a plane approximately orthogonal to the axis of the recess 344. In this context, the cut may be made or present in a plane approximately parallel to the front and back of the module 34. In other words, the cut is made or present in the direction of the median line M. According to an alternative, the cuts may be oblique to the front and back of the module 34.

Thus, one module 34 has at least two windings 341. Such windings 241 are positioned approximately parallel to each other. The

openings

347, 348 for the cooling channels can be machined individually in each winding 341.

All the above embodiments of the device 1, the transformer 30, the rectifier 40 and the above method can be used alone or in all possible combinations thereof. The features of the described embodiments and/or modifications thereof can be combined in any combination. Also, specifically, the following modifications are conceivable.

The dimensions shown in the figures are for the purpose of illustrating the principles of the invention and are not meant to be limiting. The actual dimensions of the module 34 and its components can be suitably selected to meet the functionality described above.

The elements shown in the drawings are schematically depicted and can in certain embodiments differ from the forms shown in the drawings as long as the above-described functions are ensured.

The number of

secondary windings

32, 341 can be selected as desired. The number can be at least two.

It is possible that one of the windings 341 does not have a cooling channel.

Claims

1. A welding transformer (30) for a welding tool (10), the welding transformer (30) comprising: a magnetic core (33); at least one primary winding (31), the at least one primary winding (31) being wound around the core (33) such that the at least one primary winding (31) is connectable with a power source (25) to supply a primary voltage to the at least one primary winding (31); and at least two modules (3401, 3402), wherein each module (3401, 3402) of the at least two modules (3401, 3402) is formed as one part comprising at least one secondary winding (32; 341), the at least one secondary winding (32; 341) being wound around the core (33) such that the at least one secondary winding (32; 341) is capable of converting the primary voltage into a secondary voltage (U21, U22) for supplying a welding current (I2) to the welding tool (10); and a mounting unit (342), the mounting unit (342) for mounting a rectifier (40) to the welding transformer (30) for rectifying the secondary voltage (U21, U22) for supplying a direct current as the welding current (I2) to the welding tool (10).

2. The welding transformer (30) of claim 1, wherein each module (3401, 3402) of the at least two modules (3401, 3402) comprises a coolant channel.

3. The welding transformer (30) according to claim 2, wherein the coolant channel comprises an opening (347) for an inlet and/or outlet of the coolant, and wherein the opening (347) is positioned between the at least one secondary winding (32; 341) and the mounting unit (342).

4. The welding transformer (30) according to claim 2 or 3, wherein each module (3401; 3402) of the at least two modules (3401; 3402) comprises at least one blind hole (347) and at least one through hole (348) crossing each other to form the coolant channel.

5. The welding transformer (30) according to claim 4, wherein at least one of said openings (347; 348) comprises a thread (3471; 3481) to seal said coolant channel to the outside with a threaded plug (3473).

6. The welding transformer (30) according to any of the preceding claims, wherein the form of the secondary winding (32; 341) of one module (3401; 3402) is different from the form of the mounting unit (342) of the module (3401; 3402).

7. The welding transformer (30) according to any of the preceding claims, wherein the secondary winding (32; 341) of one of the modules (3401; 3402) is connected with the mounting unit (342) of the module (3401; 3402) via a connector (343), the connector (343) being positioned offset from a neutral line (M) of the module (3401; 3402).

8. The welding transformer (30) of claim 7, wherein the welding transformer (30) comprises a first and a second module (3401, 3402) having the same external form and/or shape, and wherein the first and second modules (3401, 3402) are positioned spaced apart from each other and side by side such that the connector of the first module (3401) is positioned on the other side of the midline (M) of the first module (3401) than the connector (343) of the second module (3402).

9. The welding transformer (30) according to any of the preceding claims, wherein the at least two modules (3401, 3402) are made of copper or aluminum.

10. The welding transformer (30) according to any of the preceding claims, wherein each of the at least two modules (3401, 3402) is coated with a coating (340) protecting the module (3401; 3402) from corrosion.

11. A welding tool (10) for producing an article (4), the welding tool (10) comprising a welding transformer (30) according to any of the preceding claims and a control unit (20), the control unit (20) being configured to adjust a welding current (I2) for forming the article by joining at least two parts and/or at least two components (5; 6) of one component (5) by at least one weld joint (7).

12. Welding tool (10) according to claim 11, wherein the welding tool (10) further comprises means (50), said means (50) being adapted to move the welding tool (10) along the at least one component (5; 5, 6) according to a predetermined movement profile, and wherein the article (4) is a vehicle body.

13. A method for producing a module (3401; 3402) for a welding transformer (30), the method comprising the steps of: forming (S1) a plate-shaped module (34) such that the module (34) comprises a secondary winding (341) and a mounting unit (342) for mounting a rectifier (40) to the welding transformer (30); and machining (S2) at least one blind hole (347) and at least one through hole (348) into the module (34) such that the openings (347, 348) intersect each other to form a coolant channel in the module (34).

14. A method for producing a welding transformer (30), the method comprising the steps of: positioning (S12) a first module (3401) laterally inverted to a second module (3402), wherein the first module (3401) and the second module (3402) have at least the same external form, wherein each module (34) comprises a secondary winding (341) and a mounting unit (342) for mounting a rectifier (40) to the welding transformer (30), and wherein the first and second modules (3401; 3402) are positioned such that the secondary windings (341) of the first and second modules (3401; 3402) are positioned to face each other; positioning and fastening (S13) at least two semiconductor modules (401, 402) between the mounting units (342) of the first and second modules (3401, 3402) to build a stack, wherein the at least two semiconductor modules (401, 402) are positioned on both sides of a central module (403) of the rectifier (40) in the stack.

15. The method of claim 14, further comprising the steps of: mounting (S14, S15) a core (33) of the transformer (30) into a recess (344) of the secondary winding (341) of the at least two semiconductor modules (401, 402).