WELDING METHOD AND WELDING DEVICE FOR WELDING CONDUCTOR ENDS

Abstract

A welding method for welding grouped conductor ends of a component for an electrical machine by means of a welding device. In the method, a relative position of a first conductor end and a second conductor end of grouped conductor ends and then a first size parameter of a molten pool formed during welding are detected. Subsequently, a second size parameter of the molten pool formed during welding is detected. In a further method step, a value of the molten pool is determined from the first size parameter, the second size parameter and the relative position. Finally, a welding energy input is controlled depending on the determined value of the molten pool.

Claims

1. A welding method for welding grouped conductor ends of a component for an electric machine by means of a welding device, comprising: detecting a relative position of a first conductor end and a second conductor end of grouped conductor ends by position measurement using optical measurement methods, and subsequently, the steps of: a) detecting a first size parameter of a molten pool formed during welding; b) detecting a second size parameter of the molten pool formed during welding; c) determining a value of the molten pool from the first size parameter, the second size parameter, and the relative position; and d) controlling a welding energy input depending on the determined value of the molten pool.

2. The welding method according to claim 1, wherein step a) comprises at least one or more of the following steps: a1) detecting the first size parameter by means of optical measurement methods; a2) detecting the first size parameter by means of time-of-flight measurement of reflected radiation; a3) performing optical coherence tomography; a4) arranging a double cross relative to the grouped conductor ends, relative to an end region of the grouped conductor ends, and arranging lines of the double cross relative to each other, at a predetermined distance from each other; a5) forming a double cross, which is assigned to an end region of the grouped conductor ends, larger than a welding contour; a6) forming a double cross such that a measuring beam, which can be guided along the lines of the double cross, has at least one of predetermined jump paths or jump times; a7) alternately guiding a measuring beam to different conductor ends; a8) guiding a measuring beam to the grouped conductor ends in at least two dimensions; a9) directing a measuring beam to a first end region of a first conductor end of the grouped conductor ends, and to a second end region of a second conductor end of the grouped conductor ends, in at least two dimensions; a10) scanning a measuring beam along a double cross which is assigned to the grouped conductor ends, the double cross respectively comprising two lines which are arranged in x- and y-directions and are arranged at a predetermined distance from one another; a11) detecting a lateral extension of the molten pool as a first size parameter, in a plane of the grouped conductor ends; a12) detecting at least one input parameter, wherein as the at least one input parameter, at least one of a cross-sectional area of an end region of the grouped conductor ends or at least one conductor end is detected, a distance between the grouped conductor ends, prior to welding is detected, a height offset between the grouped conductor ends is detected, a tangential offset is detected, or a radial offset is detected, wherein the at least one input parameter is detected for determining the value.

3. The welding method according to claim 1, wherein step b) comprises at least one or more of the following steps: b1) detecting the second size parameter by means of optical measurement methods; b2) detecting the second size parameter by means of time-of-flight measurement of reflected radiation; b3) performing optical coherence tomography; b4) detecting the second size parameter at a position of a welding beam; b5) guiding or directing a measuring beam to a current position of a welding beam; b6) detecting a depth of a keyhole or a vapor capillary or a vapor channel, at a position of the welding beam; b7) detecting a depth of a keyhole or a vapor capillary or a vapor channel at a position of the welding beam in a main extension direction of the grouped conductor ends; b8) detecting a depth of a keyhole or a vapor capillary or a vapor channel in a beam direction of the welding beam; b9) detecting a gap depth during gap crossing of at least one of a measuring beam or welding beam; b10) detecting a molten pool depth; b11) detecting a molten pool depth on a surface of at least one conductor end or of the grouped conductor ends, in particular at an end region of the grouped conductor ends; b12) detecting a weld depth at a position of a welding beam; b13) correlating a detected depth at a position of a welding beam with height information in a main extension direction of the grouped conductor ends; b14) detecting at least one input parameter, wherein as the at least one input parameter, at least one of a cross-sectional area of an end region of the grouped conductor ends or of at least one conductor end is detected, a distance between the conductor ends prior to welding is detected, a height offset between the conductor ends is detected, a tangential offset is detected, a radial offset is detected, wherein the at least one input parameter is detected for determining the value.

4. The welding method according to claim 1, wherein step c) comprises at least one or more of the following steps: c1) determining a molten pool dimension of the molten pool as a value of the molten pool; c2) determining an increase in a melt volume as a value of the molten pool; or c3) determining a connection cross-section of the grouped conductor ends as a value of the molten pool.

5. The welding method according to claim 1, wherein step d) comprises at least one or more of the following steps: d1) directing a welding beam to the grouped conductor ends; d2) guiding a welding beam, repeatedly, along a symmetrical contour; d3) guiding a welding beam, repeatedly, along an elliptical contour; d4) forming a fusion ring by means of a welding beam; d5) forming a fusion blanket or a molten pool by means of a welding beam; d6) forming a weld bead; d7) starting the welding energy input to the grouped conductor ends; d8) stopping the welding energy input to the grouped conductor ends; d9) stopping the welding energy input to the grouped conductor ends when a determined value reaches a limit value; d10) adjusting, by increasing or decreasing, the welding energy input to the grouped conductor ends; d11) applying a predetermined higher welding energy input to the conductor end extending further or higher in a main extension direction of the grouped conductor ends, when there is a height offset between conductor ends in the grouped conductor ends; d12) distributing a welding energy input according to a tangential offset between the conductor ends; d13) directing two welding beams, either sequentially directing of one welding beam or simultaneous directing of two welding beams, to the grouped conductor ends, wherein one welding beam is assigned to one conductor end of the grouped conductor ends and another welding beam is assigned to another conductor end of the grouped conductor ends; d14) detecting a point in time at which two individual molten pools combine into one molten pool, a first molten pool being assigned to a first conductor end and a second molten pool being assigned to the second conductor end; d15) welding the conductor ends, at an end region or at an end face, in a parallel joint.

6. The welding method according to claim 1, wherein the detection of the relative position comprises at least one or more of the following steps: 6.1 position measuring by means of time-of-flight measurement of reflected radiation; 6.2 performing an optical coherence tomography; 6.3 alternately directing a measuring beam to different conductor end groups having at least one grouped conductor end; 6.4 measuring intervals or distances in at least two dimensions at a conductor end group; 6.5 measuring an interval or distance in a direction of an extension of conductor sections comprising conductor ends; 6.6 determining a distance between the conductor ends; 6.7 measuring a height offset between the conductor ends; 6.8 determining a cross-sectional area of an end regions of the grouped conductor ends or of at least one conductor end of the conductor ends; 6.9 determining a tangential offset between the conductor ends; 6.10 determining a radial offset between the conductor ends; 6.11 measuring at least one of a thickness, a width or a height of an end region at the conductor end group; 6.12 detecting at least one input parameter, wherein as the at least one input parameter a cross-sectional area of an end region of the grouped conductor ends or of at least one conductor end is detected, a distance between the conductor ends, prior to welding is detected, a height offset between the conductor ends is detected, a tangential offset is detected, a radial offset is detected, wherein the at least one input parameter is detected for determining the value.

7. The welding method according to claim 1, wherein 7.1 the welding method correlates at least one of the first size parameter, the second size parameter, an extension of the molten pool, a depth of a vapor channel or a vapor capillary at the position of a welding beam, at least one gap dimension or the value to at least one of corresponding sizes or corresponding data sets from preliminary experiments, or 7.2 a training data set for neural networks is formed, the training data set comprising the first size parameter, the second size parameter, an extension of the molten pool, a depth of a steam channel or a steam capillary at the position of the welding beam, at least one gap dimension, at least one of the value or data sets from previous experiments.

8. A welding device for welding grouped conductor ends of a component for an electrical machine, comprising: a welding means for welding energy input to grouped conductor ends; a measuring means for detecting a relative position of a first conductor end and a second conductor end of grouped conductor ends by position measurement using optical measurement methods, wherein the measuring means is further adapted to detect a first size parameter of a molten pool formed during welding and a second size parameter of the molten pool formed during welding, wherein the measuring means is further configured to determine a value of the molten pool from the first size parameter, the second size parameter and the relative position, and a control means is configured to control a welding energy input to the grouped conductor ends to be welded depending on the determined value.

9. The welding device according to claim 8, wherein the measuring means is at least one of

9. 1 configured for evaluating a welding result; or 9.2 comprises a comparing means for comparing the value with a predetermined limit value.

10. The welding device according to claim 8, wherein the measuring means is selected from a group of measuring means comprising:

10.1 measuring means for detecting the first size parameter using optical measuring methods;

10.2 measuring means for detecting the first size parameter by means of time-of-flight measurement of reflected radiation;

10.3 measuring means for performing optical coherence tomography;

10.4 measuring means for arranging a double cross relative to an end region of the grouped conductor ends, and arranging lines of the double cross relative to each other at a predetermined distance;

10. 5 measuring means for forming a double cross, which is assigned to an end region of the grouped conductor ends, larger than a welding contour;

10.6 measuring means for forming a double cross such that a measuring beam, which is guidable along the lines of the double cross, has at least one of predetermined jump times or jump paths;

10.7 measuring means for alternately guiding a measuring beam to different conductor ends;

10.8 measuring means for directing a measuring beam onto the grouped conductor ends in at least two dimensions;

10.9 measuring means for directing a measuring beam to a first end region of a first conductor end of the grouped conductor ends, and to a second end region of a second conductor end of the grouped conductor ends in at least two dimensions;

10.10 measuring means for tracing a measuring beam along a double cross that is assigned to the grouped conductor ends, the double cross respectively comprising two lines which are arranged in the x- and y-directions and are arranged at a predetermined distance from one another;

10.11 measuring means for detecting a lateral extension of the molten pool, as a first size parameter, in a plane of the grouped conductor ends;

10.12 measuring means for detecting at least one input parameter, wherein a cross-sectional area of an end region of the group of conductor ends or at least one conductor end, a distance between the conductor ends, prior to welding, a height offset between the conductor ends, a tangential offset, or a radial offset is detected as the at least one input parameter; or 10.13 a combination of one or more of the measuring means according to 10.1 to 10.12.

11. The welding device according to claim 8, wherein the measuring means is selected from a group of measuring means comprising: 11.1 measuring means for detecting the second size parameter using optical measuring methods; 11.2 measuring means for detecting the second size parameter by means of time-of-flight measurement of reflected radiation; 11.3 measuring means for performing optical coherence tomography; 11.4 measuring means for guiding a measuring beam to a position of a welding beam; 11.5 measuring means for detecting the second size parameter at a position of a welding beam; 11.6 measuring means for detecting a depth of a keyhole or a vapor capillary or a vapor channel at a position of a welding beam; 11.7 measuring means for detecting a depth of a keyhole or a vapor capillary or a vapor channel at a position of a welding beam in a main extension direction of the grouped conductor ends; 11.8 measuring means for detecting a gap depth during gap crossing of at least one of a measuring beam or a welding beam; 11.9 measuring means for detecting a molten pool depth; 11.10 measuring means for detecting a molten pool depth on a surface of at least one conductor end or of the grouped conductor ends; 11.11 measuring means for detecting at least one input parameter, wherein as the at least one input parameter a cross-sectional area of an end region of the grouped conductor ends or of at least one conductor end is detected, p2 a distance between conductor ends of the grouped conductor ends, prior to welding is detected, a height offset between the conductor ends is detected, a tangential offset is detected, a radial offset is detected, wherein the at least one input parameter for determining the value is detected; or 11.12 a combination of one or more of the measuring means according to 11.1 to 11.11.

12. The welding device according to claim 8, wherein the measuring means is selected from a group of measuring means comprising: 12.1 a measuring means for determining a molten pool dimension of the molten pool as a value of the molten pool; 12.2 a measuring means for determining an increase in a melt volume as a value of the molten pool; 12.3 a measuring means for determining a connection cross-section of the grouped conductor ends as a value of the molten pool; or 12.4 a combination of one or more of the measuring means according to 12.1 to 12.3.

13. The welding device according to claim 8, wherein the measuring means is selected from a group of measuring means comprising: 13.1 measuring means for position measurement by means of time-of-flight measurement of reflected radiation; 13.2 measuring means for performing optical coherence tomography; 13.3 measuring means for alternately directing a measuring beam to different conductor end groups having has at least one grouped conductor end; 13.4 measuring means for measuring intervals or distances in at least two dimensions at a conductor end group; 13.5 measuring means for measuring an interval or a distance in a direction of an extension of conductor sections comprising the conductor end; 13.6 measuring means for determining a distance between the conductor ends; 13.7 measuring means for measuring a height offset between the conductor ends; 13.8 measuring means for determining a cross-sectional area of an end region of the grouped conductor ends or of at least one conductor end of the conductor ends; 13.9 measuring means for determining a tangential offset between the conductor ends; 13.10 measuring means for determining a radial offset between the conductor ends; 13.11 measuring means for measuring at least one of a thickness, a width or a height of the end region at the conductor end group; or 13.12 a combination of one or more of the measuring means according to 13.1 to 13.12.

14. The welding device according to claim 8, wherein the control means is configured to control the welding means for: 14.1 directing a welding beam to the grouped conductor ends; 14.2 guiding a welding beam along a symmetrical contour; 14.3 guiding a welding beam along an elliptical contour; 14.4 forming a fusion ring by means of a welding beam; 14.5 forming a fusion blanket by means of a welding beam; 14.6 forming a weld bead; 14.7 starting the welding energy input to the grouped conductor ends; 14.8 stopping the welding energy input to the grouped conductor ends; 14.9 stopping the welding energy input to the grouped conductor ends when the determined value reaches a limit value; 14.10 adjusting, by increasing or decreasing, the welding energy input to the grouped conductor ends; 14.11 applying a predetermined higher welding energy input to the conductor end extending further or higher in a main extension direction of the grouped conductor ends when there is a height offset between the conductor ends; 14.12 distributing a welding energy input according to a tangential offset between the conductor ends ; and/or 14.13 directing two welding beams to the grouped conductor ends, either sequentially or simultaneously, wherein one welding beam is assigned to one conductor end of the grouped conductor ends and another welding beam is assigned to another conductor end of the grouped conductor ends; 14.14 detecting a point in time at which two individual molten pools combine into one molten pool, a first molten pool being assigned to a first conductor end and a second molten pool being assigned to the second conductor end; or 14.15 welding the conductor ends, at an end region or at an end face, in a parallel joint. 15. A computer program product including machine-readable control instructions which, when loaded into a controller of a welding device for welding grouped conductor ends of a component for an electrical machine, the welding device comprising: a welding means for welding energy input to grouped conductor ends; a measuring means for detecting a relative position of a first conductor end and a second conductor end of grouped conductor ends by position measurement using optical measurement methods, wherein the measuring means is further adapted to detect a first size parameter of a molten pool formed during welding and a second size parameter of the molten pool formed during welding, wherein the measuring means is further configured to determine a value of the molten pool from the first size parameter, the second size parameter and the relative position, and a control means is configured to control a welding energy input to the conductor ends to be welded depending on the determined value, cause the welding device to perform the welding process according claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0212] Embodiments of the invention will be described in more detail below with reference to the accompanying drawings wherein it is shown by:

[0213] FIG. 1 shows a welding arrangement comprising a welding device with a welding means, a measuring means and a control means for welding grouped conductor ends of a component for an electrical machine;

[0214] FIG. 2a-2e show a schematic representation of a top view of a pair of conductor ends to be welded with process zone conditions at different times of a welding process or progress of the process including measuring lines;

[0215] FIG. 3 show a schematic representation of a sectional view of a pair of conductor ends to be welded in the region of a keyhole with a measuring beam directed thereon;

[0216] FIG. 4a, 4b show a schematic representation of a sectional view of the pair of conductor ends to be welded with a weld seam;

[0217] FIG. 5 shows a perspective view of another pair of conductor ends with different relative positions of the conductor ends before welding;

[0218] FIGS. 6a -6d show an isometric view respectively of the pair of conductor ends to be welded at different times of a welding process or a progress of the process corresponding to the states of FIGS. 2a to 2d in perspective view;

[0219] FIGS. 7a -7d show an isometric view respectively of the pair of conductor ends to be welded at different times of a welding process or a progress of the process corresponding to the states of FIGS. 2a to 2d in side view;

[0220] FIGS. 8a -8d show an isometric view respectively of the pair of conductor ends to be welded at different times of a welding process or a progress of the process corresponding to the states of FIGS. 2a to 2d in plan view;

[0221] FIGS. 9a -9b show a side view respectively of the pair of conductor ends to be welded, with a height offset of the conductor ends;

[0222] FIG. 10 shows a schematic representation of the pair of conductor ends to be welded, with a gap between the conductor ends, in a plan view; and

[0223] FIG. 11 shows a schematic representation of the pair of conductor ends to be welded, with a tangential offset between the conductor ends, in a plan view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0224] The embodiments explained below are preferred embodiments of the invention. In the embodiments, the described components thereof each represent individual features of the invention which are to be considered independently of one another and which each develop the invention independently of one another. For this reason, these features are also to be considered as part of the invention, either individually or in a combination other than that shown. Furthermore, the embodiments described can also be supplemented by further ones of the features of the invention already described.

[0225] In the Figures, identical elements or elements having an identical function are identified by same reference signs.

[0226] FIG. 1 shows a schematic representation of a welding arrangement 10 with a welding device 12 and a component 14 to be processed. Conductor ends 18, 18a, 18b protrude from the component 14. In FIG. 1, a pair of conductor ends 20 is shown. The component 14 preferably comprises a plurality of conductors, in particular electrical conductors, and a plurality of pairs of conductor ends 20. The conductor ends 18, 18a, 18b are arranged side by side in pairs.

[0227] The component 14 is a component of an electric machine to be mass-produced, such as an electric motor to be used as a drive motor for electric or hybrid vehicles. Coil windings of the component 14 are produced by connecting conductor ends 18, in particular pairs of conductor ends 20.

[0228] For example, the component 14 is a stator of the electric motor. The conductor ends 18 are, for example, the ends, referred to as pins, of hairpins, that is, U-shaped pieces of wire, in particular rectangular wire, which are inserted into grooves of a housing or stack of laminations of the stator. By connecting the free ends of the hairpins, i.e., the pairs of conductor ends 20, the coil windings extending through the stator in a wave-like manner can be formed.

[0229] Before the coil windings are welded together, a large number of conductor ends 18 protrude from one end of the housing or one end face or surface, usually grouped into pairs of conductor ends 20. In FIG. 1, such a pair of conductor ends 20 is shown schematically. A first conductor 18a and a second conductor 18b of the pair of conductor ends 20 are to be welded together by means of a welding means 16 of the welding device 12, in particular to connect one hairpin to another hairpin. However, it may also be the case that three or more conductor ends 18 are to be connected together, which is then also to be carried out by the welding or welding process described in more detail below.

[0230] Prior to welding, the conductors, in particular the conductor ends 18a, 18b of each pair of conductor ends 20 to be welded together, are braced with each other. For this purpose, the welding device 12 may, for example, comprise a bracing means (not shown in Figures). The welding operation is explained below with reference to an example involving the pair of conductor ends 20.

[0231] For welding at least one pair of conductor ends 20, the welding device 12 comprises the welding means 16, a measuring means 22 and a control means 24. The control means 24 is coupled or connected for signaling to the measuring means 22 and/or the welding means 16, particularly in a wired or wireless fashion. The control means 24 is arranged to control the welding means 16 and/or the measuring means 22. In addition, the measuring means 22 may be arranged to transmit or send acquired parameters or values or measured variables to the control means 24. For example, the control means 24 may be configured as a control unit or controller. For example, the control means 24 has a control unit comprising a computing unit and a memory in which control instructions are stored as software.

[0232] The welding means 16 is arranged to output a welding beam 26 which is directed to a predetermined position on or at the component 14, in particular to the pair of conductor ends 20. In other words, the welding means 16 is configured to apply welding energy to the component 14, in particular the pair of conductor ends 20. In particular, the welding means 16 is configured to direct the welding beam 26 successively to a plurality of conductor ends 18. For example, the welding means 16 may be configured for beam welding. Particularly preferably, the welding means 16 may be configured for laser beam welding. Alternatively, the welding means 16 may also comprise a TIG or plasma welding device, wherein the conductor ends are moved into the welding zone one after the other.

[0233] In the preferred embodiment shown in FIG. 1, the welding means 16 has a laser for generating a laser beam as a welding beam 26 for laser welding. Hence a beam welding process is preferably performed. The welding beam 26 has a predetermined energy. The welding means 16 is further adapted to guide or direct the welding beam 26. For example, the welding beam 26 may be moved along a predetermined contour 36 by the welding means 16. The guiding or directing of the welding beam 26 may be implemented by an optical system, in particular a laser optical system, for deflecting and focusing the welding beam 26, in particular the laser beam. For example, if a laser optical system is used as the optical system, the optical system may in particular comprise one or more galvanometrically driven deflection mirrors and/or an optical element for focusing the laser beam and for adjusting the beam cross-section of the laser beam. The laser optical system may also include apertures for blanking out all or an adjustable amount of the laser beam. Thus, the laser optical system is an example of a means for directing a welding beam 26 to the conductor end group 20, and an example for starting, stopping, increasing and decreasing the welding energy input to the conductor end group 20. At least some of these functions may, of course, be performed by other suitable means, such as on the laser itself or at or in the beam path between the laser and the laser optical system.

[0234] The measuring means 22 is arranged to output a measuring beam 28. In this regard, the control means 24 is particularly adapted to control the measuring means 22 to output the measuring beam 28. For example, the measuring means 22 can output the measuring beam 28 prior to welding and thus measure or gauge the component 14 or the conductor ends 18 or determine their position. Additionally or alternatively, the measuring means 22 may be arranged to output the measuring beam 28 as soon as welding begins. In this case, the measuring means 22 is arranged to direct the measuring beam 28 to the component 14, in particular to the pair of conductor ends 20. The measuring means 22 is also arranged to guide or direct the measuring beam 28. In this context, the measuring means 22 is preferably set up to use the measuring beam 28 to move along or scan the component 14, in particular the pair of conductor ends 20, according to a predetermined pattern or according to predetermined lines, in particular measuring lines or dimension lines, and/or to guide the measuring beam 28 to a predetermined position. For example, the predetermined pattern or lines may be a double cross, which may also be referred to as a hashtag. For example, the predetermined position may be a current position of the welding beam 26 or a position of a laser spot, which is the focal point at which the welding beam hits the component 14.

[0235] Prior to welding, input parameters of the component 14 or the pair of conductor ends 20 to be welded must be determined or acquired. In other words, an initial situation of the pair of conductor ends 20 to be welded may be detected. Preferably, this initial situation or the input parameters are detected by the measuring means 22. Preferably, a cross-sectional area of an end region 32 of the grouped conductor ends 18 or at least one conductor end 18 and/or a distance between the conductor ends 18, 18a, 18b or a radial offset RV, which is, in particular, related to the radial direction of the component 14 having a central axis, and/or a gap 30 between the conductor ends 18 and/or a height offset HV between the conductor ends 18 and/or a tangential offset TV between the conductor ends 18 and/or a relative position of the conductor ends are detected as input parameters. The at least one or more input parameters are preferably collected by the measuring means 22. The pin positions or positions of the conductor ends 18 can be characterized with respect to the input parameters, particularly preferably with respect to HV, RV and TV. In FIGS. 2a, FIG. 5, FIG. 6a, FIG. 7a and FIG. 8a, examples of corresponding initial situations in which the conductor ends may be arranged prior to welding are shown. In particular, FIG. 5 specifically highlights or illustrates the tangential offset TV, the radial offset RV, and the height offset. For example, a welding energy input may additionally or alternatively be controlled depending on the collected input parameter or parameters.

[0236] Moreover, the measuring means 22 is adapted to detect a first size parameter and a second size parameter of a molten pool 34 formed during welding. In other words, the measuring means 22 is arranged to detect or measure at least two size parameters of the molten pool 34 during welding. As a first size parameter, in particular an extension or expansion or length of the molten pool 34 in a predetermined first direction and a predetermined second direction, in particular in one plane or two dimensions, is detected. For example, an extension of the molten pool 34 in an x-direction, which extends in particular parallel to a cross-sectional area or transverse plane of the conductor ends 18, and in a y-direction, which extends in particular perpendicular to the x-direction and/or parallel to a cross-sectional area or transverse plane of the conductor ends 18, is detected. The detection of the expansion of the molten pool 34 in the x- and y-directions will be discussed in more detail below in connection with FIGS. 2a to 2e. In particular, a depth of a hole, in particular a keyhole 44, at the current position of the welding beam 26 is detected as a second size parameter. In other words, an extension or an expansion of the molten pool 34 in a z-direction, which extends, in particular, perpendicular to the x- and y-directions or perpendicular to the cross-sectional area or in a main extension direction of the conductor ends 20, is detected. The detection of the expansion of the molten pool 34 in the z-direction will be discussed in more detail in connection with FIG. 3. Thus, by means of the first size parameter and the second size parameter, in particular a geometry of the molten pool 34 or a molten pool geometry is detected or determined.

[0237] In addition, the measuring means 22 is arranged to determine or detect or calculate a value of the molten pool 34 from the first size parameter and the second size parameter. In particular, a connection cross-section is calculated as the value. Additionally or alternatively, the control means 24 may also be arranged to calculate the value of the molten pool 34. For this purpose, the measuring means 22 may transmit or transfer the detected or determined size parameters to the control means 24.

[0238] Finally, the control means 24 is adapted to control a welding energy input depending on the determined value of the molten pool 34. In particular, the value to be determined results from the input parameter or parameters and/or the first size parameter value and/or the second size parameter value. The control means 24 or a comparing means (not shown in the Figures), which may form part of the measuring means 22 or the control means 24, is further arranged to compare the determined value with a limit value, i.e., in particular a predetermined value of a connection cross-section. Once the determined value has reached the limit value, the control means 24 controls the welding means 16 to stop the welding energy input, i.e., the output of the welding beam 26. Additionally or alternatively, the control means 24 may be arranged to control the welding means 16 in such a way that a welding energy input is increased or reduced, depending on the determined value.

[0239] In the preferred exemplary embodiment shown in FIG. 1, the measuring means 24 operates via time-of-flight measurement of reflected measuring radiation 28. Particularly preferably, the measuring means 22 operates using optical coherence tomography (OCT). For this purpose, the measuring means 22 has, for example, an OCT device. The OCT device may comprise a deflection means, which is, in particular, also referred to as a scanner. Such OCT devices for performing optical coherence tomography are available on the market for completely different purposes as can be seen, for example, from the following literature:

[0240] [2] “Optical coherence tomography”, entry in Wikipedia, wikipedia.org, retrieved on May 12, 2021.

[0241] They are currently used in medicine, particularly for detecting the fundus of the eye in ophthalmology. The deflection device of the OCT device allows a measuring beam 28 of the OCT device to scan or be guided over the respective conductor ends 18. Thus, the measuring means 24 is adapted to detect a position of the contours of the individual conductor ends 18 or also the contours, the dimensions and the volume of the molten pool 34, hence the first and the second size parameters, or of the welding bead 42 or the welding seam 48.

[0242] In connection with FIGS. 2a to 2e, FIGS. 6a to 6d, FIGS. 7a to 7d, FIGS. 8a to 8d and FIG. 3, the detection of the first size parameter and the second size parameter by means of the measuring means 22, in particular the OCT device, will be discussed in more detail. Prior to the welding process, the measuring means 22 is used to determine the positions and/or contours of the uncut hairpins in the x-y-z direction, i.e., in particular the positions of the conductor ends 18a and 18b, relative to one another. In particular, as is shown schematically in FIG. 5, the input parameters, especially preferably the tangential offset TV, the radial offset, a gap 30 between the conductor ends 18a, 18b and/or a height offset HV and/or a relative position, are detected or determined here. This initial situation before welding is shown in FIG. 2a, FIG. 6a, FIG. 7a and FIG. 8a. Here, the measuring device emits the measuring beam 28, in particular, with a defined wavelength, preferably of 840 nm.

[0243] The measurement strategy is configured as a double cross, as shown in

[0244] FIGS. 2a to 2e. The double cross has four lines or measuring lines M1 to M4, as can be seen in FIGS. 2a to FIG. 2e. In particular, the double cross is arranged in a plane relative to the end region 32 of the conductor ends 18 relative to the end region. In other words, the double cross may be in a plane with the end portion 32 or the end surfaces of the conductor ends 18, 18a, 18b. In other words, the double cross may be placed or projected on the end region 32 of the grouped conductor ends 18. The double cross has the four measuring lines M1 to M4, two of which are arranged parallel to each other at a predetermined distance, i.e. M1-M2 and M3-M4, and the respective pair of lines of which the two lines run parallel to each other runs or is arranged perpendicular to the other pair of lines, i.e. the two pairs of lines are arranged or set up in a cross to each other.

[0245] By means of this measurement strategy, the molten pool dimension is first determined in the x- and y-directions during welding. In other words, an expansion or extension or dimension of the molten pool 34 is determined as a first size parameter, in particular in a plane or in two dimensions perpendicular to the main extension direction of the conductor ends 18 or conductors. The lateral extension of the molten pool 34 in the x- and y-directions is thereby determined in particular via the two lines respectively arranged in the x- and y-directions, the measuring lines M1 to M4, with a defined spacing from one another. At the measurement during welding, the measuring beam 28 is guided exclusively along the measuring lines M1 to M4. The molten pool 34 is formed during welding. The molten pool 34 is formed as the welding beam 26 impinges on the component 14, in particular the conductor ends 18. An expansion of the molten pool 34, in particular a volume expansion in the area of the molten pool 34, shortens the measured distance or travel time of the measuring beam 28. Thus, a geometric change of the molten pool 34 can be detected. This can additionally or alternatively serve as an input variable for dimensioning the energy input. The expansion of the molten pool 34 is formed, in particular, by the fact that the welding beam 26 is moved along the contour 36, i.e., travels along the component 14, in particular along the conductor ends 18 with a predetermined distance and melts the component 14 in this area. Due to the expansion of the molten pool 34 and with the distance or running time measured shortening with it, a conclusion can be drawn about the melt, i.e., the molten pool 34, within the contour 36. In other words, after a complete contour run, it can be determined whether the inner surface of contour 36 is completely filled with melt. By contour 36 is meant, in particular, a path along which the welding beam 26 is moved, in particular on the conductor ends 18 or the end region 32 of the conductor ends 18. As shown, in particular in FIG. 6b and FIG. 6c, the welding beam 26 is moved along a predetermined contour 36. The contour 36 may also be referred to as the welding contour. In particular, the welding beam 26 travels along an elliptical contour 36. Thus, while the welding beam 26 travels along the predetermined contour 36, the measuring beam 28 is simultaneously guided along the measuring lines M1 to M4. Once the welding beam 26 has travelled along the contour, especially the elliptical contour, while the welding beam 26 moves along the contour 36, the measuring beam 28 can travel along the measuring lines M1 to M4 and can determine, as soon as the welding beam has completely travelled along the contour 36, whether the contour 36, i.e. especially the interior thereof, is filled with melt. The welding beam 26 can also travel over the contour multiple times. In doing so, the welding beam 26 can travel over the contour 36 or various contours several times until the desired welding result or expansion of the molten pool 34 is achieved. Figures FIG. 2b, FIG. 6b, FIG. 7b and FIG. 8b show how the welding beam 26 travels along such a contour 36. A spot or focal point is formed at the position where the welding beam 26 hits the component 14. Since a laser beam is used as the welding beam 26, a so-called laser spot 50 is formed. The laser beam is moved along an elliptical contour 36 until a fusion ring 38 is formed. With the measurement strategy, the process zone dimension can be measured iteratively during the welding process by measuring the dimensions of the molten pool 34 along the measuring lines M1 to M4. This allows defined limit values of the connection cross-section to be achieved.

[0246] FIG. 2c and FIG. 2d, FIGS. 6c and 6d, FIGS. 7c and 7d and FIGS. 8c and 8d illustrate the further process progress during welding. Shown therein is the enlargement of the contour 36 and the molten pool 34. FIG. 2e shows the resulting weld bead 42 and the weld 48. In FIG. 4a, the weld 48 is shown or illustrated in a longitudinal section to a plane of the joint. In FIG. 4b, the weld 48 is shown in cross-section.

[0247] In the measuring strategy as shown in FIGS. 2b to 2e, in particular the contour 36 is arranged via the position of the measuring lines M1 to M4 relative to the conductor ends 18 and relative to each other. Here, in particular, a predetermined edge distance is maintained, the double cross being configured to be larger in comparison with the dimension of the predetermined contour 36. By means of experiments, for example, it can be determined which minimum distances of the measuring lines M1 to M4 are required or have to be assumed relative to one another in order to determine the molten pool dimension in the x- and y-directions by means of which a required connection cross-section is achieved. In addition, the double cross is configured especially circumferentially in in such a way that minimum jump paths and/or jump times result.

[0248] The input parameter or parameters, which are determined, in particular, before welding, are determined by the measuring means 26 also using, in particular, this measuring strategy with the four measuring lines M1 to M4.

[0249] FIG. 6a to FIG. 6d, FIG. 7a to FIG. 7d and FIG. 8a to FIG. 8d show the stages in the welding process, from an initial state (FIG. 6a, FIG. 7a and FIG. 8a) via the formation of a fusion ring 38 and the closing of the fusion blanket 40 to a formation, in particular complete formation, of a bead 42 or melt bead. FIG. 6a, FIG. 7a and FIG. 8a show an initial state prior to the welding process. FIG. 6b, FIG. 7b and FIG. 8b show how the welding beam 26 is guided along the predetermined, elliptical contour 36. Once the welding beam 26 has completely travelled along the contour 36, a fusion ring 38 or the closed melt contour is formed. FIG. 6c, FIG. 7c and FIG. 8c show the closed fusion blanket 40 or the molten pool 34 within the contour 36. FIG. 6d, FIG. 7d and FIG. 8d show a development of a weld bead 42.

[0250] After a complete run through the double cross, as shown in FIGS. 2a to FIG.

[0251] 2e, the measuring means 26 is used to measure the keyhole 44, as shown in FIG. 3. In this case, the measuring beam 28 is guided to or jumps to a current position of the laser spot 50, that is, the point or position or location where the laser beam impinges on the conductor ends 18. In this case, a measuring beam 28 is emitted in a specific wavelength. At this position or location, the measuring means 22, in particular the OCT device, measures or determines a depth of the keyhole 44 as a second size parameter value. The measuring means 22 determines the keyhole depth by calculating the propagation time of the reflected signal 46, as schematically shown in FIG. 3. From this, height information of the component 14 in the z-direction can be determined. In other words, height information can be generated via the propagation time of the reflected radiation. This height information correlates, in particular, with an extension or height or depth of the molten pool 34 in the z-direction. Thus, a geometric change of the molten pool 34 can be detected. This can serve as an input variable for dimensioning the energy input.

[0252] The determination of the molten pool dimension is particularly necessary because there are cases in which not the entire wire cross-section is melted, for example in the case of a wide gap in which the melt flows into the gap. If the line distances are too large, the melt may possibly not reach the measuring lines M1 to M4 if the gap size is too large, so that too much energy, i.e., welding energy, would be introduced, although there is already a sufficient connection cross-section before the melt reaches the measuring lines.

[0253] After measuring with the measuring means 22, the molten pool dimension in the x- and y-directions, i.e., the first size parameter, and the location-related depth of the molten pool 34, i.e., the second size parameter, are known. From this, the melt volume and/or connection cross-section, i.e., the value, is calculated or determined by means of geometric observation. Alternatively, the melt volume can be used to determine the connection cross section. The melt volume and/or the connection cross-section can be determined by the measuring means 22 or the control means 24. Depending on the measuring progress and the melting progress, the increase in the melt volume is preferably determined and thus the connection cross-section. When a limit value is reached, the emission of the laser energy is stopped. In the measurement process, therefore, the measuring lines M1 to M4 can first be scanned and then the measuring beam 28 can be moved to the current position of the welding beam 26. These measuring steps can be repeated once or several times, in particular in this order.

[0254] In the case of differences in the geometric symmetrical position of the conductor ends 18 to be welded, an asymmetrical molten pool 34 is produced along the contact surface, since the energy is input symmetrically, for example via elliptical contours, and since the heat conduction leads to equal energy distribution into the two conductor ends 18a, 18b in the case of equal shares of irradiation.

[0255] FIGS. 9a and 9b, FIG. 10 and FIG. 11 show three cases in which the irradiation location and the surface energy or the welding energy input are controlled depending on the wire cross-section or the cross-section of the conductor ends 18, 18a, 18b and the measurement signal (OCT) 46.

[0256] Case A is shown in FIGS. 9a and 9b. This case represents a height offset HV, significantly larger, as shown in FIG. 5 or FIG. 2a or FIG. 6a. Case B is shown in FIG. 10. This case represents a radial offset RV. The radial offset RV refers to the radial direction of the component 14 having a central axis. Case C is shown in FIG. 11. This case represents a tangential offset TV between the ends of the conductor.

[0257] Depending on the case (A-C), an implementation of the surface energy or welding energy input takes place according to the present geometric boundary conditions (A-C), so that a homogeneous welding bead 42 is produced or formed.

[0258] In case A of a height offset HV, the main part of the energy, i.e., the welding energy input, is applied to the higher conductor end or the higher pin, i.e., in this case the conductor end 18a, so that there is an identical height level of both welded conductor ends 18. During gap crossing, i.e., in particular a travel of the welding beam 26 from one conductor end 18a to the other conductor end 18b, the keyhole depth is measured and used as a measured variable, i.e., the second size parameter, for calculating the connection area or the connection cross-section.

[0259] In case B of a radial offset RV, two pin-related welding contours are involved to avoid energy input into the gap. That is, a first welding contour 36a is formed on the first conductor end 18a and a second welding contour 36b is formed on the second conductor end 18b by the welding means 16. The control means 24 can be arranged to control the welding means 16 in such a way that two welding beams are directed to the grouped conductor ends 18, one welding beam being assigned to one conductor end 18a, 18b of the grouped conductor ends 18 and the second welding beam being assigned to a further conductor end 18a, 18b of the grouped conductor ends 18. In particular, the welding means 16 may be arranged to direct a respective welding beam 26 sequentially or two welding beams simultaneously to the conductor ends. Particularly preferably, the welding beam 26 is first directed to the first conductor end 18a and then to the second conductor end 18b. The measurement contour in the form of a double cross can be maintained. Here, the point in time at which the two individual molten pools combine into a common molten pool 34 is to be tracked. In other words, a point in time can be recorded at which the two individual molten pools unite to form a molten pool 34, the first molten pool being assigned to the first conductor end 18a and the second molten pool being assigned to the second conductor end 18b. Concerning the measurement of the molten pool depth, in case B, the keyhole depth cannot be used as an evaluation variable because the keyhole is open downward, so that little or no signal response is returned. In this case, the information regarding the molten pool depth in the gap, i.e., the second size parameter value, is to be drawn from the molten pool depth on the pin surface, i.e., a surface of the conductor ends 18 or the respective conductor end.

[0260] In case C of the tangential offset TV, a distribution of the surface energy or welding energy input takes place according to the tangential offset present. If elliptical welding contours are used, the longitudinal axis must be rotated accordingly so that it intersects the centers of the individual pins or conductor ends. In particular, the elliptical welding contour runs around the center points of the respective conductor ends. The elliptical welding contour is arranged inclined to a longitudinal axis of the conductor ends at a predetermined angle. Accordingly, the contour of the double cross is to be set at an angle. The double cross can be adjusted in such a way that a shape or surface enclosed by the lines or the lines form a rhombic shape or contour. Analogous to case A), i.e., in the case of a height offset, the joint plane of the joining partners, i.e., in particular of the conductor ends, is used to evaluate the process zone depth.

[0261] The boundary conditions A to C can be present in different combinations to each other and thus the process can be combined according to the boundary conditions as described above.

[0262] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF REFERENCE SIGNS

[0263] 10 welding arrangement [0264] 12 welding device [0265] 14 component [0266] 16 welding means [0267] 18 conductor ends [0268] 18a first conductor end [0269] 18b second conductor end [0270] 20 pair of conductor ends [0271] 22 measuring means [0272] 24 control means [0273] 26 welding beam [0274] 28 measuring beam [0275] 30 gap [0276] 32 end zone [0277] 34 molten pool [0278] 36 contour [0279] 36a first contour [0280] 36b second contour [0281] 38 fusion ring [0282] 40 fusion blanket [0283] 42 bead [0284] 44 keyhole [0285] 46 signal [0286] 48 weld [0287] 50 laser spot [0288] HV height offset [0289] M1 first measuring lines [0290] M2 second measuring lines [0291] M3 third measuring lines [0292] M4 fourth measuring lines [0293] RV radial offset [0294] TV tangential offset