EP3796345A1

EP3796345A1 - Welding transformer, method for producing a module for a welding transformer and method for producing a welding transformer

Info

Publication number: EP3796345A1
Application number: EP19198194.3A
Authority: EP
Inventors: Damjan Rihtarsic
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-09-19
Filing date: 2019-09-19
Publication date: 2021-03-24
Also published as: CN112530684A

Abstract

There is provided a welding transformer (30), a method for producing a module (34; 3401; 3402) for a welding transformer (30) and a method for producing a welding transformer (30). The welding transformer (30) comprises a magnetic core (33), at least one primary winding (31) wound around the core (33) such that the at least one primary winding (31) can be connected with a power supply (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 component which comprises at least one secondary winding (32; 341) wound around the core (33) such that the at least one secondary winding (32; 341) can transform the primary voltage into a secondary voltage (U21, U22) used for supplying a welding current (I2) to the welding tool (10), and a mounting unit (342) for mounting to the welding transformer (30) a rectifier (40) for rectifying the secondary voltage (U21, U22) to supply a direct current as the welding current (I2) to the welding tool (10).

Description

The present invention relates to a welding transformer, a method for producing a module for a welding transformer and a method for producing a welding transformer.
Welding transformers are used by welding tools for providing a predetermined current to join metallic components of an article by at least one weld. For producing a weld, a welding tool may be guided by hand or a robot. The transformer is often attached to the welding tool to omit a bulky high-voltage cable. In such a case, the transformer needs to be optimized in weight and size to make the handling of the welding tool easy. This facilitates, too, to keep the power consumption of the welding tool low.
Such light weight welding transformers are usually connected with a rectifier. The transformer transforms a primary alternating current into a secondary alternating current with the desired intensity and time characteristics. The secondary side of the transformer is connected to a rectifier which rectifies the current output from the transformer and provides a direct current to at least one welding electrode of the welding tool. If the welding electrodes are contacted to a metal component and the corresponding welding current is fed to the welding electrode, a weld may be produced.
One problem lies in that the current produced by the transformer-rectifier-unit produces a high amount of heat. This requires cooling of the transformer-rectifier-unit, for example by water as a coolant. Due to this, the transformer and the rectifier are usually made from a plurality of different parts to allow for cooling of the unit and for a compact size of the unit.
Another problem lies in that, the plurality of different parts is to be connected such that sufficient stability is achieved to allow a secure operation for moving the welding tool around. Herein, hard-soldering is needed which causes oxidation of the soldered parts. Thus, the parts have to be cleaned laboriously.
All this renders the assembly of the transformer-rectifier-unit rather intricate. Consequently, the transformer-rectifier-unit is expensive.
Therefore, 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 can solve 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 can simplify and enhance the assembly of the transformer-rectifier-unit so that a light-weight transformer-rectifier-unit may 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 comprises a magnetic core, at least one primary winding wound around the core such that the at least one primary winding can be connected with a power supply to supply a primary voltage to the at least one primary winding, and at least two modules, wherein each module of the at least two modules is formed as one component which comprises at least one secondary winding wound around the core such that the at least one secondary winding can transform the primary voltage into a secondary voltage used for supplying a welding current to the welding tool, and a mounting unit for mounting to the welding transformer a rectifier for rectifying the secondary voltage to supply a direct current as the welding current to the welding tool.
In the described welding transformer, the number of metallic components or modules is reduced to a minimum, since no separate secondary winding and no separate rectifier mounting unit is present. The described welding transformer has the further advantage that hard soldering is not needed any more. The modules are constructed such that a joint with the other components of the transformer is possible by fastening elements like screws, only. Since the number of components is reduced, only a small number of joints with the fastening elements are to be produced. Due to this, the construction of the transformer-rectifier-unit is more stable than a transformer-rectifier-unit having more parts and needs thus more joints with fastening elements. This results also in a better efficiency due to reduced current losses.
The above described welding transformer is thus constructed such that the assembly of the single components or modules of the welding transformer is rendered easier than for a transformer having a separate secondary winding and a separate rectifier mounting unit.
Further advantageous developments of the welding transformer are set out in the dependent claims.
Possibly, each module of the at least two modules comprises a coolant channel.
According to one configuration, the coolant channel comprises an opening for an inlet and/or an 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 module of the at least two modules comprises at least one blind opening and at least one through opening which cross each other to form the coolant channel. Herein, at least one of the openings comprises a thread for sealing the coolant channel with a threaded plug to the outside.
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 displaced from a midline of the module.
It is conceivable that the welding transformer comprises a first module and a second module which have the same outer form and/or shape, wherein the first and second modules are positioned spaced from each other and side by side so 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, the at least two modules are made from copper or from aluminium.
In a specific configuration, each one of the at least two modules is coated by a coating protecting the module against corrosion.
The above described welding transformer may be part of a welding tool for producing an article. The welding tool may further comprise a control unit configured to adapt a welding current for forming the article by joining at least two parts of one component and/or at least two components by at least one welding joint. Herein, the welding tool may further comprise a device for moving the welding tool according to a predetermined moving profile along the at least one component, 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 steps of: forming a plate-shaped module such that the module comprises a secondary winding and a mounting unit for mounting a rectifier to the welding transformer, and machining at least one blind opening and at least one through opening into the module such that the openings cross each other to form a coolant channel in the module.
The method achieves the same advantages as they are mentioned above in respect of 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 steps of positioning a first module side-inverted to a second module, wherein the first module and the second module have at least the same outer form, wherein each module comprises a secondary winding and a mounting unit for mounting a rectifier to the welding transformer, and wherein the first and second modules are positioned such that the secondary winding of the first and second modules are positioned faced to 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 in the stack on both sides of a center module of the rectifier.
The method may further comprise the step of mounting a core of the transformer into a recess of the secondary windings of the at least two semiconductor modules.
The method achieves the same advantages as they are mentioned above in respect of the welding transformer.
Further possible implementations of the invention comprise also combinations of features or styles described above or in the following with reference to the embodiments, even if they are not mentioned explicitly. Herein, the person skilled in the art will also add single aspects as improvements or additions to the respective basic form of the invention.
Further implementations of the invention are subject matter of the embodiments of the invention described in the following.
In the following, the invention is described in more detail by means of embodiments and with reference to the appended drawing figures, wherein:

Fig. 1 schematically shows a block diagram of a plant having a welding device according to an embodiment;
Fig. 2 shows a three dimensional view of a raw module for a welding transformer of the welding device according to the embodiment;
Fig. 3 shows a plan view of a first module which is achieved after openings for a cooling channel and for mounting are machined in the module of Fig. 2;
Fig. 4 shows a plan view of a second module which is achieved after openings for a cooling channel and for mounting are machined in the module of Fig. 2;
Fig. 5 shows a side view of an assembly of the symmetrically positioned first and second modules of Fig. 3 and Fig. 4;
Fig. 6 shows a first side view of an assembly of the modules of Fig. 5 with components or modules of a rectifier;
Fig. 7 shows a second side view of the assembly of the modules of Fig. 5 with components or modules of a rectifier;
Fig. 8 shows a bottom view of the assembly of the modules of Fig. 5 with components or modules of a rectifier;
Fig. 9 shows a flow chart for illustrating 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 drawing figures, the same or functionally same elements are provided with the same reference signs unless given otherwise.
Fig. 1 shows very schematically a plant 1 having a welding device 2. The welding device 2 is in particular a resistance welding device. The plant 1 is a production plant for producing articles like vehicles, household devices, heaters, or the like.
In the plant 1, metallic components 5, 6 may be connected such that a welding 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 which comprises two welding electrodes 11, 12, a control unit 20, a welding transformer 30 and a rectifier 40. In the example of Fig. 1, the welding tool 10 is moved by a device 50. The device 50 might be a robot.
The welding device 2 may produce a welding joint 7 with the welding tool 10 by control of the control device 20. Herein, two edges of a single component 5 may be connected by one or more welding joints 7, for example. Independent from the number of components 5, 6 which are connected by a welding joint 7, the welding joint(s) may be produced by at least one welding spot or at least one welding seam or a combination of both.
The welding transformer 30 is mounted to the rectifier 40 so that a transformer-rectifier-unit is provided.
The welding transformer 30 has a primary winding 31 and a secondary winding 32 which are both positioned at a common core 33. The primary winding 31 is connected to a power supply 25 which supplies the necessary power and voltage U1 for welding, which is shown by the left arrow in Fig. 1. The secondary winding 32 has three outputs 35, 36, 37 so that a first secondary voltage U21 and a second secondary voltage U22 is produced. The first secondary voltage U21 and the second secondary voltage U22 form a welding voltage U23 which results in a welding current I2 at the output of the transformer-rectifier-unit. The welding transformer 30 is in the shown example a medium frequency direct current transformer (MF-DC-transformer).
The rectifier 40 has in the example of Fig. 1 a first to fourth semiconductor devices 41 to 44, for example transistors 41 to 44. The first semiconductor device 41 is connected to a 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 welding tool 10. More detailed, the series connection of the first and second semiconductor devices 41, 42 is connected between the secondary winding 32 of the transformer 30 and the first welding electrode 11.
To a second output 36 of the transformer 30, the second welding electrode 12 is connected.
The third semiconductor device 43 is connected to a third output 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 welding tool 10. More detailed, the series connection of the third and fourth semiconductor devices 43, 44 is connected between the secondary winding 32 of the transformer 30 and the first welding electrode 11.
In case 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 12.
Fig. 2 shows a raw module 34 which is configured to connect the transformer 30 and the rectifier 40. The raw module 34 is formed from one component. The component is made from metal, in particular copper or aluminium, or at least one other metal which enable electric conduction. Copper and aluminium are advantageous as regards their comparable small electric resistance and simultaneously a high thermic conductivity.
Possibly, the module 34 is coated by a coating 340, as shown only very schematically in Fig. 2. The coating 340 may protect the module 3401, 3402 against corrosion. For example, the coating 340 may be a coating for passivating the aluminium or an aluminium alloy, in particular the coating may be an anodization. Alternatively, the coating 340 may be a galvanic coating. 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 in addition, the coolant may comprise a corrosion inhibitor.
The raw module 34 has a plate-like form. The raw 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 raw module 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. The outer edges of the secondary winding 341 are bevelled in the example of Fig. 2. 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 with the mounting unit 342 by the connector 343. The second end 3412 is a free end of the secondary winding 341. Herein, the second end 3412 projects from the secondary winding 341 in the direction of the mounting unit 342. The second end 3412 is positioned faced to the mounting unit 342. The second end 3412 is positioned spaced by the first gap 345 from the mounting unit 342. 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 at one of its four corners to the connector 343. The connector 343 is positioned displaced from a midline M of the module 34. The midline M is approximately orthogonal to the axis of the recess 344.
The connector 343 has an approximately rectangular cross section in the example of Fig. 2. Herein, the long side of the rectangular connector 343 is positioned transverse to the long side of the mounting unit 342. The first gap 345 is delimited on one side by a part of the long side of the mounting unit 342.
The connector 343 is at least partly positioned side by side to the second end 3412. The second end 3412 is positioned spaced from the connector 343 by the second gap 346. Thus, the second gap 346 separates the second end 3412 and the connector 343. In the example of Fig. 2, the second gap 346 is cascaded. Thus, the first end 3412 of the secondary winding 341 is cascaded as well.
The second gap 346 is delimited on one side by a part of the long side of the connector 343 and a part of the secondary winding 341. The second gap 346 separates the connector 343 and the first end 3411 of the secondary winding 341. Further, the 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 so that the gaps 345, 346 have approximately an angular shape or L-shape. The gaps 345, 346 are to be filled by an electrically insulating material. In Fig. 2, the electrically insulating material is air so that the gaps 345, 346 are air gaps.
Fig. 3 shows a plan view of a first module 3401 which was produced starting from the raw module 34 of Fig. 2 by machining first and second cooling channel openings 347, 348 for a cooling channel into the raw module 34 of Fig. 2. Machining may be made by drilling holes as openings 347, 348.
The first openings 347 are blind openings. The second opening 348 is a through opening. At least one of the openings 347 is provided at its open end with a thread 3471. Moreover, the opening 348 is provided at each of its open ends with a thread 3481. In addition, third openings 349 are 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 at its open end with a thread 3491.
The openings 347, 348 of the first module 3401 are positioned transverse to each other so that at least two of the openings 347, 348 cross each other. Therewith a cooling channel is built through the module 3401.
Fig. 4 shows a plan view of a second module 3402 which was produced starting from another raw module 34 as shown in Fig. 2 by machining first and second cooling channel openings 347, 348 for a cooling channel into such a raw module 34 of Fig. 2. As in the module 3401 of Fig. 3, the first openings 347 of the module 3402 in Fig. 4 are blind openings. The second opening 348 is a through opening. At least one of the openings 347 is provided at its open end with a thread 3471. Moreover, the opening 348 is provided at each of its open ends with a thread 3481. In addition, third openings 349 are 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 at its open end with a thread 3491.
The openings 347, 348 of the second module 3402 are positioned transverse to each other so that at least two of the openings 347, 348 cross each other. Therewith a cooling channel is built through the module 3402.
As a result, the first and second modules 3401, 3402 have the same outer form and/or shape. However, the openings 347, 348 for the cooling channel may be different for the first and second modules 3401, 3402, as derivable from Fig. 3 and Fig. 4.
For assembly of the transformer 30 and the rectifier 40, the modules 3401, 3402 are positioned to each other as shown in Fig. 5.
As derivable from Fig. 5, the first and second modules 3401, 3402 are positioned spaced from each other and side by side. In combination with Fig. 2 to 4 it is clear from Fig. 5 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.
In other words, the modules 3401, 3402 are positioned symmetrically to each other but side-inverted to each other in the transformer 30 as shown in Fig. 5. In still other words, the first and second module 3401, 3402 are turned by approximately 180° to each other, namely around the midline M of one of the modules 3401, 3402 shown in Fig. 2. As a result, the windings 341 of the modules 3401, 3402 are faced to each other. And, the mounting units 342 of the modules 3401, 3402 are faced to each other. However, the connectors 343 of the modules 3401, 3402 are positioned on two different sides of the stack built by the modules 3401, 3402.
According to Fig. 6 to 8, the rectifier 40 and the modules 3401, 3402 may be mounted into one unit. In this unit, the openings 347, 348 are sealed by seals 3405 or plugs 3473. Therewith, the openings 347, 348 are closed such that no coolant may leak from the modules 3401, 3402. Thus, the coolant may circulate in the modules 3401, 3402 to perform heat dissipation from the unit built 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 comprises a contact unit 45 for the connection to a plus pol and a contact unit 46 for the connection to a minus pol. The contact units 45, 46 are configured to deliver the welding current I2 to the welding electrodes 11, 12.
The rectifier 40 further comprises a first welding semiconductor module 401, a second welding semiconductor module 402, a center rectifier module 403, a first spring package module 404, a second spring package module 405 and fastening devices 408 with ends 409. The modules 401 to 405 are stacked with the modules 3401, 3402 as shown in Fig. 6 to Fig. 8. The stack built by the modules 401 to 405 and modules 3401, 3402 is fastened with the fastening devices 408. For this purpose, the fastening devices 408 are inserted through openings 349 in all of the modules 401 to 405, 3401, 3402. Herein, the spring package modules 404, 405 perform a spring force to provide a pressure or a holding force which holds together the stack built by the modules 401 to 405.
The first welding semiconductor module 401 is positioned between the first module 3401 and the center plate 403. The first welding semiconductor module 401 might comprise the semiconductor devices 41, 42 of the circuit shown in Fig. 1. Alternatively, the semiconductor module 401 comprises a diode for rectifying the voltage U21 shown in Fig. 1.
The second welding semiconductor module 402 is positioned between the second module 3402 and the center plate 403. The second welding semiconductor module 402 might comprise the transistors as the semiconductor devices 43, 44 of the circuit shown in Fig. 1. Alternatively, the semiconductor module 402 comprises a diode for rectifying the voltage U22 shown in Fig. 1.
The first spring package module 404 is positioned spaced to the first welding semiconductor module 401. The second spring package module 405 is positioned spaced to the second welding semiconductor module 402. Thus, the stack of the rectifier 40 comprises the first spring package module 404, the first module 3401, the first welding semiconductor module 401, the center rectifier module 403, the second welding semiconductor module 402, the second module 3402, and the second spring package module 405 in this order.
As shown in Fig. 7, the cooling channel built from the openings 347, 348 in the modules 3401, 3402 of Fig. 3 and Fig. 4 is sealed to the outside of the modules 3401, 3402 by the seals 3405. The openings 347 provided with the seals 3405 may be used as inlet or outlet of the coolant channel. Each of the seals 3405 serves to seal the corresponding winding 341 such that leakage of the coolant out of the coolant channel is prevented. The opening 347 with the seal 3405 is positioned between the at least one secondary winding 341 and the mounting unit 342. The opening 347 with the seal 3405 is positioned in the second end 3412 of the secondary winding 341.
The contact unit 46 for the connection to a minus pol is configured to connect to the cooling channel at the opening 347 sealed with the seal 3405 that is shown in Fig. 5 and Fig. 7.
Fig. 8 shows in addition to Fig. 6 and Fig. 7 fastening devices 410 for fastening the contact unit 46 to the rectifier 40.
Fig. 9 shows very schematically a method for producing a module 3401 as shown in Fig. 3 or a module 3402 as shown in Fig. 4.
The method has a step S1 in which a raw module 34 is built in one piece. Herein, a raw material is formed such that the raw module 34 has the winding 341, the mounting unit 342, the connector 343, the recess and the gaps 345, 346 as shown in Fig. 2. The raw module 34 may be built by cutting out of the raw material the winding 341, the mounting unit 342, the connector 343, the recess and the gaps 345, 346 as shown in Fig. 2. Cutting may be made by a laser or as water cutting. Alternatively, the raw module 34 may be built by moulding or three-dimensional printing. The raw module 34 may be provided with the coating 340, as well. Thereafter, the flow goes further to a step S2.
In the step S2, the openings 347, 348, 349 are machined. Machining of the openings 347, 348, 349 may be performed with a drilling machine. At least a part of the openings 347, 348, 349 may be etched. Optionally, the raw module 34 may be provided with the coating 340 after machining the openings 347, 348, 349. In this case, the openings 347, 348, 349 may be protected against corrosion as well. Thereafter, the flow goes further to a step S3.
In the step S3, the threads 3471, 3481, 3491 of the openings 347, 348 are machined. Machining of the openings 347, 348 may be performed with a thread cutter. Optionally, the raw module 34 may be provided with the coating 340 after machining the threads 3471, 3481, 3491 of the openings 347, 348, 349. In this case, the openings 347, 348, 349 completed with the threads 3471, 3481, 3491 may be protected against corrosion as well. Thereafter, the flow goes further to a step S4.
In the step S4, plugs 3473 may be fastened, in particular screwed, into the threads 3471, 3481 of the openings 347, 348 for the coolant channel. Further, a seal 3405 may be inserted into an opening 347 of the respective module 3401, 3402 to provide an inlet or an outlet of the coolant channel. Thereafter, the method ends.
The steps S1 to S4 may be performed for at least two modules 3401, 3402 to build a transformer-rectifier-unit as shown in Fig. 6 to Fig. 8. Herein, the steps S1 to S4 may be performed at least partly simultaneously.
Fig. 10 shows very schematically a method for producing a transformer 30 as described above by reference to Fig. 5 to Fig. 8.
The method has a step S11 in which at least one of the modules 3401, 3402 is provided. The term "provided" includes that at least one of the modules 3401, 3402 is produced as described above by reference to Fig. 9. Thereafter, the flow goes further to a step S12.
In the step S12, at least two modules 3401, 3402 are assembled with 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 welding semiconductor module 401, the center rectifier module 403, the second welding semiconductor module 402, the second module 3402, and the second spring package module 405 are positioned in this order adjacent to each other. Herein, the first and second module 3401, 3402 are at least identical in their outer form and/or shape. The first and second module 3401, 3402 are turned by 180° to each other so 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 the fastening elements 408 which are inserted and fastened into the third openings 349 of the modules 401 to 405, 3401, 3402. Thereafter, the flow goes further to a step S13.
In the step S13, the contact unit 45 for the connection to a plus pol and a contact unit 46 for the connection to a minus pol are mounted to the stack built in the step S12. This may be made with screws, too. Thereafter, the flow goes further to a step S14.
In the step S14, the secondary windings 341 are mounted on the core 33 of the transformer 30. For this purpose, the core 33 is inserted into the recess 344 of the secondary windings 341. Further, the at least one primary winding 31 is mounted on the core 33. Thereafter, the flow goes further to a step S15.
In the step S15, at least the secondary windings 341 are moulded with resin, in particular epoxy resin. Thereafter, the method ends.
The steps S11 to S14 may be performed at least partly simultaneously. Additionally or alternatively, the steps S11 to S14 may be performed at least partly in a changed order.
Therewith, a low cost welding transformer 30 may be built without hard soldering. The welding transformer 30 has a minimum of single parts and is very stable in construction.
According to a second embodiment, the module 34 of Fig. 2 is further cut in a plane which is approximately orthogonal to the axis of the recess 344. Herein, the cut may be made or present in a plane which is approximately parallel to the front and back face of the module 34. In other words, the cut is made or present in a direction of the midline M. According to an alternative, the cut may be inclined to the front and back face of the module 34.
Therewith, one module 34 has at least two windings 341. Such windings 241 are approximately positioned in parallel to each other. The openings 347, 348 for a cooling channel may be machined in each winding 341 separately.
All of the above-described implementations of the plant 1, the transformer 30, the rectifier 40 and the above-described methods can be used separately or in all possible combinations thereof. The features of the described embodiments and/or their modifications can be combined arbitrarily. Moreover, in particular, the following modifications are conceivable.
The dimensions shown in the drawings are used for illustrating the principle of the invention and are not limiting. The actual dimensions of the module 34 and the components thereof can be selected as appropriate to fulfil the above described functionality.
The elements shown in the figures are depicted schematically and can differ in the specific implementations from the forms shown in the figures provided that the above-described functions are ensured.
The number of the 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

A welding transformer (30) for a welding tool (10), the welding transformer (30) comprising a magnetic core (33), at least one primary winding (31) wound around the core (33) such that the at least one primary winding (31) can be connected with a power supply (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 component which comprises at least one secondary winding (32; 341) wound around the core (33) such that the at least one secondary winding (32; 341) can transform the primary voltage into a secondary voltage (U21, U22) used for supplying a welding current (12) to the welding tool (10), and a mounting unit (342) for mounting to the welding transformer (30) a rectifier (40) for rectifying the secondary voltage (U21, U22) to supply a direct current as the welding current (12) to the welding tool (10).
The welding transformer (30) according to claim 1, wherein each module (3401, 3402) of the at least two modules (3401, 3402) comprises a coolant channel.
The welding transformer (30) according to claim 2, wherein the coolant channel comprises an opening (347) for an inlet and/or an 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).
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 opening (347) and at least one through opening (348) which cross each other to form the coolant channel.
The welding transformer (30) according to claim 4, wherein at least one of the openings (347; 348) comprises a thread (3471; 3481) for sealing the coolant channel with a threaded plug (3473) to the outside.
The welding transformer (30) according to any one 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).
The welding transformer (30) according to any one 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) which is positioned displaced from a midline (M) of the module (3401; 3402).
The welding transformer (30) according to claim 7, wherein the welding transformer (30) comprises a first module (3401) and a second module (3402) which have the same outer form and/or shape, and wherein the first and second modules (3401, 3402) are positioned spaced from each other and side by side so 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).
The welding transformer (30) according to any one of the preceding claims, wherein the at least two modules (3401, 3402) are made from copper or from aluminium.
The welding transformer (30) according to any one of the preceding claims, wherein each one of the at least two modules (3401, 3402) is coated by a coating (340) protecting the module (3401; 3402) against corrosion.
A welding tool (10) for producing an article (4), comprising a welding transformer (30) according to any one of the preceding claims, and a control unit (20) configured to adapt a welding current (12) for forming the article by joining at least two parts of one component (5) and/or at least two components (5; 6) by at least one welding joint (7).
The welding tool (10) according to claim 11, wherein the welding tool (10) further comprises a device (50) for moving the welding tool (10) according to a predetermined moving profile along the at least one component (5; 5, 6), and wherein the article (4) is a vehicle body.
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 opening (347) and at least one through opening (348) into the module (34) such that the openings (347, 348) cross each other to form a coolant channel in the module (34).
A method for producing a welding transformer (30), the method comprising the steps of positioning (S12) a first module (3401) side-inverted to a second module (3402), wherein the first module (3401) and the second module (3402) have at least the same outer 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 winding (341) of the first and second modules (3401; 3402) are positioned faced to 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 in the stack on both sides of a center module (403) of the rectifier (40).
A method according to claim 14, further comprising the step of mounting (S14, S15) a core (33) of the transformer (30) into a recess (344) of the secondary windings (341) of the at least two semiconductor modules (401, 402).