DE102009052464B4 - Method for welding strips of different materials together using an electron beam and device for carrying out the method - Google Patents

Abstract

Method for welding together strips (3.1, 3.2) of different materials using an electron beam (5) in a vacuum, the strips (3.1, 3.2) being welded together on their long sides, wherein:- a device with an electron gun (1) for carrying out the method, which is flanged to a recipient (2), is used with a beam deflection system and lenses in order to generate an energy field on the surface of the bands (3.1, 3.2) to be joined, - the bands (3.1, 3.2) to be joined, made of different materials, below the electron gun (1) are arranged in the recipient (2) and moved continuously in the longitudinal direction, - an energy transmission field is positioned over a joint (6) of the strips (3.1, 3.2), and - the energy transmission field is an energy input zone, forming one or more melting zone(s). ) (21) in the belts (3.1, 3.2), the different belts (3.1, 3.2) having different temperatures in the immediate vicinity of the melting zone(s) (21), with an electron collector ( 7) the electrons (8) passing through the joint (6) are detected by the electrons (8) passing through the joint (6) being collected as a current in the electron collector (7) which pass through the joint (6). arriving electrons (8), which are caught as a current in the electron collector (7), are evaluated with a computing system and the values determined are compared with a target value, with a correction value being determined with an immediately subsequent correction of the position of the energy transmission field transverse to the welding direction, with the energy transmission field initially in the direction of the better heat-dissipating material of the tapes (3.1, 3.2) is shifted transversely to the tape feed direction.

Description

The invention relates to a method for welding strips of different materials together by means of a charge carrier beam, preferably an electron beam, with the strips being butt-welded together on their longitudinal sides. The strips butt-welded together at the longitudinal edges are punched or cut transversely to the weld seam into shaped elements for further use, which is not the subject of the invention, and these shaped elements are preferably used for the production of resistors or other electrical/electronic components, for example as bimetals.

It is known to guide these bands to be welded together through welding systems known per se and to carry out the welding process in order to join the two bands together. It is known to carry out the weld by means of an electron beam, the electron beam being relatively guided along the two edges in order to produce the weld.

In the production of trimetals, it is known that two different electron beam sources are arranged one behind the other in the direction of strip travel, each producing the weld seams on one longitudinal side.

The regulation of the position of the electron beam and the necessary relative movement transverse to the direction of travel of the strip is carried out separately for each electron beam source via a manual control circuit as a result of, for example, mechanical and/or thermal width tolerances of the strips.

In the area of the joint, the strips to be welded are mechanically positioned vertically and horizontally. As a rule, a force is then applied horizontally via rollers, which compresses the bands in the joint area in order to minimize the joint gap.

The strips to be welded often have unequal thicknesses. In addition, an electron collector is positioned under the joint in the area of the respective electron beam source in order to catch the electrons escaping from the underside of the joint (penetrating electrons). The penetration current that can thus be determined is measured and displayed by means of a measuring device.

Welding is usually carried out with an increased proportion of energy in the thicker material, which is usually copper and is located in the center of the energy input, so that when the position is shifted in the direction of the thinner material, the displayed value increases. A larger amount of electrons escapes from the root of the weld. The root develops stronger and thereby damages the edges of the ligaments. If you move the electron beam source too far towards the thinner material, the electron beam will penetrate completely and unintentionally eject material downwards, and the weld will be defective.

However, shifting the electron beam source transversely to the direction of strip travel has the disadvantage that the position of the energy field changes and the weld seam shifts to the left or right in relation to the direction of strip travel.

The correct position of the respective energy transfer field, as well as the correct beam parameters, such as beam current, lens current, stigmator, etc., so that welding is 100% penetration, can only be determined after the strips have passed through the electron beam welding system in a destructive test. Alternatively, the position of the weld can be assessed with a visual inspection in the running process by evaluating the root of the weld, and then by moving the electron beam source while comparing with the display, a better and satisfactory weld is achieved.

When producing trimetals, this process is repeated completely for the second electron beam source, which produces the second weld seam.

This method also has a decisive disadvantage that the subjective, manual manual control is sluggish, the required manual control is very error-prone, and the probability of errors occurring in the weld seam is therefore relatively high, since the time between the occurrence and detection of position deviations or changes in the energy transmission field is a manual one Regulation for eliminating a fault is very long. In the meantime, significant lengths of material have become wasted at the high welding speeds that are common. The risk of making covert errors is also very high. As a result, one is forced to accept lower weld depths than 100% penetration. However, this means that there is no possibility of checking the actual depth of the weld seam. It is practically impossible during the welding process to check the actual weld depth without seeing the root. It is therefore also not possible to prove without destructive tests which weld seam depth has been reached in relation to the target depth.

Furthermore, occurring thermal tolerances of the joining devices as well as mechanical tolerances of the thickness and the width of the strips have a negative effect on the weld, particularly in connection with the material of the strips.

Ultimately, these defects also lead to the fact that both the mechanical and the electrical parameters of the finished welded strips are negatively influenced.

The process does not allow the strips to be welded 100% reliably, especially not in the case of sliding or sudden parameter changes in the area of the electron beam source.

One is practically helpless in the time domain when an electron beam source changes the energy distribution and/or the position of the energy transfer field as a result of the slow thermal degradation of the cathode.

It is not possible with any of the known methods to separate changes in the area of the energy distribution in the focal spot, which lead to fluctuations in the depth of the weld, from position errors. Overall, it can be stated that with the known methods it is not possible to produce such products in a highly productive manner with the highest quality requirements.

From the pamphlet DD 269 809 A1 discloses a method for welding metallic materials that can only be welded to one another to a limited extent by means of electron beams. In order to achieve the required degree of mixing of the joining partners and to compensate for evaporation losses, the publication DD 269 809 A1 proposed to design the joint geometrically in such a way that the cross-section of the material with the higher evaporation rate and the better thermal conductivity is increased compared to the other material and thus provides an excess of material in the area of impact of the electron beam.

The pamphlet EP 0 780 188 A1 includes a plate made of at least two sheets of aluminum or aluminum alloys welded together by electron beam welding. The individual sheets can be composed of different materials and have different thicknesses. The pamphlet EP 0 780 188 A1 describes that a continuous production of a blank strip is possible in that the metal sheets are continuously joined as parallel rolled strips by electron beam welding to form a blank strip.

The pamphlet JP S56 - 4 388 A discloses an electron beam welding system in which an electron beam detector is provided below the steel plates to be welded together, which detects the electron beam passing through the joint when the welding depth is deeper than a preset value.

Also in print JP S55 - 144 389 A For example, in an electron beam welding device, a beam current penetrating through a welding point is detected, compared with a preset value, and then the magnetic flux density of a focusing coil of the electron beam welding device is adjusted to control the electron beam density.

From the pamphlet JP S58 - 221 685 A there is known an electron beam welding apparatus in which an electron beam penetrating through a body to be welded is guided through an aluminum film to a fluorescent material which emits light. The wavelength of the emitted light is detected by a photodetector and converted into an electrical signal, which in turn is used to control the electron beam.

The object of the invention is to provide a method for butt-joining longitudinal edges of at least two strips of different material by means of a charge carrier beam, preferably an electron beam, by welding, the weld seam being produced at very high speed. Deviations in the thickness of the material and slight mechanical deviations on the edges to be welded must not negatively affect the quality of the weld. The seam must be produced consistently with high quality over the entire length. The root development should be very fine and edge damage in the root area can be almost completely ruled out. The weld seam depth should be one hundred percent.

All deviations, whether process-related or material-dependent, must be compensated for as far as possible automatically, so that errors occurring during welding are compensated almost without inertia or displayed as errors. This means that even at high speeds of welding the strips together, there is extremely little waste.

In the event of a fault that cannot be compensated for by the control process, the electron beam must be switched off immediately to prevent rejects, or the process must be interrupted.

Furthermore, a device is to be created which uses known electronic components and an electron beam source known per se to carry out the method. The facility should carry out the process with an electron beam source, regardless of the number of weld seams to be produced.

The object is achieved by a method according to claim 1 and a device according to claim 14. Advantageous embodiments of the invention are the subject matter of dependent claims 2 to 13 and 15 to 20.

• - zur Durchführung des Verfahrens eine Einrichtung mit einer Elektronenkanone, die auf einem Rezipienten angeflanscht ist, mit Strahlablenksystem und Linsen, um auf der Oberfläche der zu verbindenden Bänder ein Energiefeld zu erzeugen, verwendet wird,
• - die zusammenzufügenden Bänder unterschiedlichen Materials unterhalb der Elektronenkanone in dem Rezipienten angeordnet und in Längsrichtung kontinuierlich bewegt werden,
• - ein Energieübertragungsfeld über einer Fügestelle der Bänder positioniert wird, und
• - das Energieübertragungsfeld eine Energieeintragszone unter Ausbildung einer oder mehrerer Schmelzzone(n) in den Bändern erhitzt, wobei die verschiedenen Bänder verschiedene Temperaturen in unmittelbarer Umgebung der Schmelzzone(n) haben,

mit einem unter den Bändern angeordneten Elektronenauffänger die durch die Fügestelle hindurch gelangenden Elektronen erfasst werden, indem die durch die Fügestelle hindurch gelangenden Elektronen im Elektronenauffänger als Strom aufgefangen werden, die durch die Fügestelle hindurch gelangenden Elektronen, welche im Elektronenauffänger als Strom aufgefangen werden, mit einem Rechensystem ausgewertet werden und die ermittelten Werte mit einem Sollwert verglichen werden, wobei eine Korrekturwertermittlung mit sofort anschließender Lagekorrektur des Energieübertragungsfeldes quer zur Schweißrichtung erfolgt, wobei das Energieübertragungsfeld zunächst in Richtung des besser Wärme ableitenden Materials der Bänder quer zur Bandvorschubrichtung verschoben wird.The method according to the invention is a method for welding together strips of different materials using an electron beam in a vacuum, with the strips being welded together on their long sides, with:

• - to carry out the method, a device with an electron gun flanged onto a recipient, with a beam deflection system and lenses to generate an energy field on the surface of the bands to be connected is used,
• - the bands of different materials to be joined are arranged below the electron gun in the recipient and are continuously moved in the longitudinal direction,
• - an energy transfer field is positioned over a joint of the ribbons, and
• - the energy transfer field heats an energy input zone to form one or more melting zone(s) in the bands, the different bands having different temperatures in the immediate vicinity of the melting zone(s),

the electrons passing through the joint are detected with an electron collector arranged under the belts, in that the electrons passing through the joint are collected as a current in the electron collector, the electrons passing through the joint, which are collected as current in the electron collector, with a computer system are evaluated and the values determined are compared with a target value, with a correction value being determined with an immediately subsequent correction of the position of the energy transmission field transverse to the welding direction, with the energy transmission field initially being shifted in the direction of the better heat-dissipating material of the strips transverse to the strip feed direction.

An essential prerequisite for solving the task, taking into account important boundary conditions, is that the energy transfer function, which carries out the energy input directly in the joint, is kept constant by keeping the vacuum in the recipient constant within narrow limits by means known per se.

In addition to the actual vacuum control, the avoidance of evaporating lubricant residues from the surface of the belts is of particular importance. As a result of the good thermal conductivity of copper and similar material in combination with a relatively small strip thickness, a large area leading heat-affected zone with high temperatures arises, which, if lubricant residues are present, may lead to large-area evaporation and thus to changes in the vacuum. In addition to the well-known influence of the vacuum on the energy transfer function (lens effect), a variable ionization component is added due to the variable surface contamination, because the belts used may not be evenly oiled, which means that the evaporation rate varies. This circumstance makes it necessary to first clean the strips of evaporating lubricant residues before inserting the strips into the welding system.

A special ion collector is used to minimize the influence of ions on the electron beam and the beam generator system. This electrostatically deflects ions out of the path of the electron beam.

Likewise, the mechanical joining conditions, in particular the height offset and edge deformation, e.g. B. by cutting edge deformations in the production of the tapes used, kept constant, or minimized in a suitable manner.

Preferably, mechanical methods should be used that come very close to the goal of minimizing edge deformation. Suitable for this is z. B. edge milling, because here, in addition to eliminating the fracture surfaces after cutting through longitudinal splits, transverse deformations of the strips can also be largely removed.

The mechanical processing of the joining edges immediately before the joining process guarantees joints that are largely free of dirt and oxide.

These are further prerequisites for the continuous welding process, which, however, do not directly serve to solve the task, but only have to be taken into account.

The method according to the invention should also be applicable to the welding of materials of the same thickness and of different metallurgical composition.

According to the invention, this object is achieved in that the energy transmission field is automatically shifted transversely to the belt feed direction, the penetrating electrons are detected by means of an electron collector and evaluated with a suitable computer system. The determined values are compared with a target value. From this it follows whether the position of the energy transmission field needs to be corrected.

From the result of the evaluation of the penetrating electrons, the position of the energy transfer field is adjusted and optimized according to a mathematical model, and/or the electron beam current and/or the lens current and/or the stigmators are automatically varied.

This takes into account that the electron beam current must be reduced compared to the start and the achievement of the stable thermal state, because material that has already been heated is now continuously being welded.

This regulation of the parameters of the charge carrier beam, in particular of the electron beam, for optimizing and adjusting the energy transfer field takes place in a known manner after a test weld has been carried out.

In order to carry out the method, it is advantageous to position the energy transmission field directly over the joint in a known manner in a first step. To do this, the energy transfer field dimensions in the X and Y directions are set to zero. This means that the entire energy is concentrated in the center and brought to bear for a short time. A small local melting point (called point) is the result at zero tape feed speed. This so-called point marks the energy center of the energy transmission field as a small crater on the material.

Thereafter, the position of the pointer(s) relative to the joint is observed optically or electron-optically and, if necessary, shifted to the desired position above the joint gap by mechanical and/or electron-optical corrections. If the point is located exactly above the joint gap, the actual energy transfer figure can be called up and the welding process started.

The energy transfer field heats the energy input zone. The two-dimensional energy transfer area becomes a three-dimensional area and the vapor capillary with the melting zone and heat-affected zone is formed. Gas mixing and melting zone mixing begin inside the capillary. In the solid material area, the energy dissipation takes place exclusively through pure heat dissipation.

Thereafter, in order to eliminate the imbalance in energy dissipation in the region of the fusion zone, first the energy transfer field is slightly shifted in the direction of the better heat-dissipating material.

Then the welding process is started and the fusion zone is formed. The penetration electrons emerge in the root area and are collected as a current in the electron collector. This means that the information required is initially available to begin the evaluation process. The penetration current is first conducted to a demultiplexer via a measuring line. This assigns z. For example, when welding two weld seams in parallel, the information on the left or right weld seam is added in order to determine the necessary correction values for each weld pool separately. The penetration electrons are then evaluated and compared with a target value and the correction value is determined with immediately subsequent correction of the position of the energy transmission field perpendicular to the welding direction. This position correction is carried out electron-optically by the deflection control or electromechanically by a mechanical axis which is used to shift the electron beam source (electron gun).

The possibility of an automatic mechanical correction of the position of the energy transfer field is due to the masses to be moved when several melting zones are generated simultaneously from an electron beam source (jump beam welding), but only to a limited extent with tri-band welding.

On the way to reaching the optimal operating point, the thermal and mechanical conditions change continuously. The onset of temperature-related different length and width expansion shifts the joint away from the starting point and the flow temperature field is formed.

Mechanical demands on the subsequent joint can have a significant impact on the welding speed, since different crystalline phases are formed depending on the time-temperature transformation process (called TTT behavior) of the solidifying melt, whose mecha nical properties can differ significantly.

This means that the initial settings of the beam parameters, the position of the energy transfer field and the beam current settings are not optimal.

Finally, with the help of the evaluation of the penetration electrons with a processor using a mathematical model, the position of the energy transfer field(s) is first adjusted and optimized. To do this, the signals are first smoothed, compared with specified limits and correction values are determined. The beam current is reduced after the stable thermal state has been reached because, unlike at the start of the welding process, from now on the material is continuously welded into warmer material.

The structural composition of the weld seam is determined and optimized with separate metallurgical investigations and the range for the optimum welding speed is determined.

Optionally, both the electron beam current and/or the lens current and/or the stigmators are now varied automatically.

Here, too, an optimization cycle is run through several times with the aid of the mathematical model and one parameter is changed in each case and the measurement result is compared with a desired function.

The setpoint functions can be provided with a technologically required offset.

Thus, the system has the automatic correction factors energy transfer field position, beam current correction, and lens current correction,

The system is always online during the welding process.

In tri-band welding in particular, the mechanical and thermal tolerance fields of the bands add up.

Since the position of the second weld seam varies significantly more due to the specific process conditions (mechanical tolerances, temperature, spatter formation, etc.), a very fast control process is required.

The system according to the invention works almost without inertia.

The device for carrying out the method consists of a beam generating device known per se, preferably an electron gun with the usual beam deflection system and lenses, in order to generate an energy field adapted to the method on the surface of the materials to be connected.

The bands of different materials to be joined are arranged below the electron gun, these move continuously in the longitudinal direction and the electron beam can be deflected in any direction.

To minimize the influence of ions on the electron beam and the electron gun system, a special ion collector is required below the deflection systems for energy transfer field generation but above the strips to be welded. This is electrically isolated and provided with a negative voltage and arranged parallel to the axis of the electron beam. It electrostatically deflects ions out of the path of the electron beam.

Directly below the belts, the system is insulated against high voltage and protected against overvoltages, an electron collector on varistors is arranged in the middle under the weld seam to be produced, which is connected to a demultiplexer / (electronic switch) via a signal line.

A fast demultiplexer is integrated in the area of the deflection control so that a quasi-simultaneous correction during spring beam welding (tri-band welding with an electron beam source) is possible. The demultiplexer enables the penetrating electrons caught by the electron collector to be allocated to the left or right of the molten bath that is charged with energy (electrons).

In order to be able to make the necessary changes to the beam field density and/or beam parameters and/or lenses, the deflection control must have at least 3 channels (X, Y, Z).

The X-axis and the Y-axis usually describe the energy transfer function and the Z-axis controls the demultiplexer.

The invention is described using an exemplary embodiment. In the accompanying drawings, the facilities are shown in principle.

• 1: eine Einrichtung zur Durchführung des Verfahrens,
• 2: den Aufbau der Messeinrichtung.

Show it:

• 1 : a facility for carrying out the procedure,
• 2 : the structure of the measuring device.

1 shows the electron gun 1, which is flanged to the recipient 2, the NC axis of which can be displaced in the direction of the arrow (X and Y direction) transversely to the transport direction of the two strips 3.1 and 3.2 to be welded together. In this case, the band 3.1 is made of resistance material; the band 3.2 is made of copper. The vacuum can be regulated within a defined fine range in the recipient 2 in a known manner via a valve 4 . The generated electron beam 5 is kept constant during the welding at the joint 6 of the strips 3.1 and 3.2. Among bands 3.1; 3.2, an electron collector 7 is arranged, which detects the electrons 8 (penetrating electrons) passing through the joint 6, which are then fed to the processor 9 via a demultiplexer 10. The processor 9 then sends a signal to the deflection controller 11 of the electron gun 1 in order to correspondingly regulate its axis position in the X and/or Y direction. The associated deflection control 11
is connected to a CNC control with panel 12 and a correction field with data display 13.

The ion collector 14 is arranged parallel to the beam axis of the electron gun 1 .

• In einem an sich bekannten Schritt als eine Vorstufe des erfindungsgemäßen Verfahrens wird das Energieübertragungsfeld direkt mittig über der Fügestelle 6 positioniert. Dazu werden die Energieübertragungsfeldabmessungen in X - Richtung und Y - Richtung auf Null gesetzt. Das besagt, dass sich die gesamte Energie des Elektronenstrahls 5 im Zentrum konzentriert und kurz zur Einwirkung kommt. Ein kleiner lokaler Schmelzpunkt (Point) ist bei einer Bandvorschubgeschwindigkeit von Null das Resultat. Dieser Point kennzeichnet auf dem Material das Energiezentrum des Energieübertragungsfeldes in Form eines kleinen Kraters.

The procedure is carried out in the following steps:

• In a step known per se as a preliminary stage of the method according to the invention, the energy transmission field is positioned directly in the center above the joint 6 . To do this, the energy transfer field dimensions in the X - direction and Y - direction are set to zero. This means that the entire energy of the electron beam 5 is concentrated in the center and has an effect for a short time. A small local melting point (Point) is the result at zero tape feed speed. This point marks the energy center of the energy transmission field on the material in the form of a small crater.

In a further known step that follows, the position of the point in relation to the joint 6 is observed optically or electron-optically, and if necessary, the mechanical and/or electron-optical corrections to the desired position over the joint 6 between the two bands 3.1 and 3.2 postponed. If the point is located exactly above the joint 6, the actual energy transfer figure is called up in a known manner and the welding process is started immediately.

The energy transfer field now heats the energy input zone. A three-dimensional area arises from the two-dimensional energy transfer area, because the vapor capillary with melting zone 21 and heat-affected zone are formed. Gas mixing and melting zone mixing begin inside the vapor capillary. Both in the molten and in the solid material area, the heat dissipation takes place exclusively through pure heat dissipation.

Since the coefficient of thermal conductivity of the different materials differs depending on their metallurgical composition, completely different temperatures occur in the various strips 3.1 and 3.2 in the immediate vicinity of the melting zones 21, i.e. at a distance from the melting zone 21.

For example, copper has a thermal conductivity of 395 W/m*K at 20 °C, and pure nickel only 90.7 W/m*K. Mn/Ni alloys (e.g. manganin, a manganese-nickel alloy) only have a thermal conductivity of 22 W/m*K, i.e. only 5.6% of the thermal conductivity of copper.

The isotherms in band 3.2 made of copper are therefore significantly further apart than in band 3.1 made of resistance material. As a result, significantly more energy is dissipated in the copper, which means the copper stays colder.

The resistance material heats up faster in the immediate vicinity of the melting zone 21 and reaches the melting temperature much more quickly, especially since the specific heat of fusion of the metals also differs significantly.

From the uneven distribution of the melting zone 21, it can be seen that less energy is required to reach the target melting depth than in copper, and the weld seam is therefore 100% welded faster. The so-called spike formation starts on the side of the resistance material. At the same time, this is associated with the emergence of the electrons 8 in the area of the root 15 of the weld seam.

In a now following 3rd step, which is the most important inventive step, in order to eliminate the imbalance in the energy dissipation in the region of the melting zone 21, the energy transmission field is first shifted in the direction of the better heat-dissipating material transversely to the direction of strip feed.

For this purpose, the evaluation of the electrons 8, which is known per se, takes place automatically and by comparison with a target value, and then the mechanical or electron-optical correction of the position of the energy transmission field perpendicular to the welding direction. This position correction is done electron-optically by the deflection control 11 or electromechanically by shifting the axis of the electron gun 1.

On the way to reaching the optimal operating point, the thermal and mechanical conditions change continuously. The onset of temperature-related different length and width expansion shifts the joint 6 away from the starting point, and the flow temperature field is formed.

As a result, both the initial settings for the position of the energy transfer fields and the beam current settings are no longer exact.

The next step according to the invention is then carried out, in which the position of the energy transfer field is initially adapted and optimized with the aid of the evaluation of the penetration electrons 8 using a mathematical model.

The beam current is reduced after the stable thermal state has been reached, since, unlike at the start of the welding process, continuously warmer material is now being welded. The beam current as well as the lens and/or the stigmators are varied automatically.

This mathematical model is run through several times in an optimization cycle, and one parameter is changed in each case, with the measured value being compared with a target function. The target functions are provided with a technologically required offset. With this, the system has automatic correction factors, energy transfer field position, beam current correction, and lens current correction, while the system is always online during the welding process.

Necessary components known per se for carrying out the method are in 1 shown. There is a lens control 22, a display 23 and a deflection amplifier 24 which form an assembly with other components mentioned above. The high-voltage generator 26 is used to generate the high voltage required for the operation of the electron gun 1. Ultimately, this assembly is connected via the line 27 to an error output (not shown).

2 also shows the structure of the measuring device arranged below the bands 3.1 and 3.2, with three bands, a middle one 3.1 made of resistance material, being welded to both sides with a band made of copper 3.2 in this exemplary embodiment. The root 15 of the weld forms under the weld. The electron collector 7 is separated from ground by insulators 16, with a varistor 17 being connected between them and ground. Line 18 is as stated 1 seen first to demultiplexer 10 and after knowing which side is being energized, then to processor 9 to determine the deflection X,Y offsets. The electron beam 5 is guided by the deflection controller 11 to the deflection figure 20 provided with the respective offsets.

An embodiment of the method according to the invention is that it is not only suitable for connecting two bands by means of a weld seam, but also for tri-band welding, in which three bands of different material are welded together to produce a band. As a rule, the middle band 3.1 is made of a resistive material and is connected to a copper band 3.2 on both sides. The two weld seams are produced independently of one another, but according to the invention.

With tri-band welding, the mechanical and thermal tolerance fields of the bands add up.

Since the specific process conditions (mechanical tolerances, temperature, spatter formation, etc.) mean that the position of the second weld seam varies significantly more, a very fast control process is required.

The method according to the invention has the significant advantage that it can be used to butt weld metal strips made of different materials and also with different thicknesses on the long sides using the electron beam, with a very high welding speed being possible compared to the known methods. The quality of the weld is very high and the rejects are extremely low.

In the case of a faulty weld that cannot be ruled out, but rarely occurs, the fault is recognized immediately, and the effect of the fault on the weld seam is almost completely ruled out by an almost inertia-free position correction, possibly in connection with the correction of the vacuum. In the event of major errors, the controller causes immediate shutdown. This means that even at the high welding speed in relation to the production volume, the possible rejects are extremely low.

The method according to the invention is also used to produce welded joints, in which materials of different types and geometries are to be connected. Especially such welders bonds that the specialist could not previously produce due to the material differences.

Reference List

1

electron gun

2

recipient

3

Tape;

3.1

made of resistance material;

3.2

made of copper

4

Valve

5

electron beam

6

joint

7

electron collector

8th

electrons

9

processor

10

demultiplexer

11

deflection control

12

CNC tableau

13

data display

14

ion scavenger

15

root of the weld

16

insulator

17

varistor

18

Line

20

distraction figure

21

melting zone

22

lens control

23

screen

24

deflection amplifier

26

high voltage generator

27

Line

Claims (20)

Method for welding together strips (3.1, 3.2) of different materials using an electron beam (5) in a vacuum, the strips (3.1, 3.2) being welded together on their long sides, with: - a device with an electron gun (1), which is flanged onto a recipient (2), with a beam deflection system and lenses, in order to generate an energy field on the surface of the bands (3.1, 3.2) to be connected, is used to carry out the method, - the strips (3.1, 3.2) of different materials to be joined are arranged below the electron gun (1) in the recipient (2) and are continuously moved in the longitudinal direction, - an energy transmission field is positioned over a joint (6) of the strips (3.1, 3.2), and - the energy transfer field heats an energy input zone to form one or more fusion zone(s) (21) in the belts (3.1, 3.2), the different belts (3.1, 3.2) having different temperatures in the immediate vicinity of the fusion zone(s) (21), the electrons (8) passing through the joint (6) are detected with an electron collector (7) arranged under the bands (3.1, 3.2), in that the electrons (8) passing through the joint (6) are collected in the electron collector (7) are collected as a current, the electrons (8) passing through the joint (6), which are collected as a current in the electron collector (7), are evaluated with a computer system and the values determined are compared with a target value, with a correction value determination being immediately Subsequent correction of the position of the energy transmission field takes place transversely to the welding direction, the energy transmission field first being shifted in the direction of the better heat-dissipating material of the strips (3.1, 3.2) transversely to the direction of strip feed. procedure after claim 1 , characterized in that the position is corrected electron-optically by a deflection control (11) or electromechanically by an axis displacement of the electron gun (1). Method according to one of the preceding claims, characterized in that with the aid of the evaluation of the electrons (8) passing through the joint (6), which are collected as a current in the electron collector (7), with a processor (9) using a mathematical The position of the energy transmission field is adjusted and optimized using the model, whereby signals are smoothed, compared with specified limits and correction values are determined. procedure after claim 3 , characterized in that the electron beam current and/or the lens and/or the stigmators are automatically varied during the welding process, with the aid of the mathematical model being used to run through an optimization cycle several times and in each case one parameter is changed and the measurement result is compared with a setpoint function. Method according to one of the preceding claims, characterized in that when the energy transmission field over the joint point (6) is positioned, the entire energy of the electron beam (5) is concentrated in the center and a local melting point is generated. procedure after claim 5 , characterized in that the position of the local melting point in relation to the joint (6) is viewed optically or electron-optically. procedure after claim 6 , characterized in that the position of the local melting point is shifted to a desired position above the joint (6) between the strips (3.1, 3.2) to be joined by mechanical and/or electron-optical corrections. Method according to one of the preceding claims, characterized in that ions are deflected from the path of the electron beam (5) by an ion collector (14) arranged parallel to the electron beam (5) above the strips (3.1, 3.2) to be welded. Method according to one of the preceding claims, characterized in that the vacuum in the recipient (2) is kept constant. Method according to one of the preceding claims, characterized in that the method is a method for spring jet welding, ie for the simultaneous production of a plurality of melting zones from the electron gun (1). Method according to one of the preceding claims, characterized in that the strips (3.1, 3.2) are cleaned of evaporating lubricant residues before the strips (3.1, 3.2) are introduced into the welding system. Method according to one of the preceding claims, characterized in that the stream of electrons (8) passing through the joint (6) collected in the electron collector (7) is conducted to a demultiplexer (10) which collects the electrons collected by the electron collector (7). Assigns electrons (8) to the molten bath to which energy is applied. Method according to one of the preceding claims, characterized in that when setpoint values are exceeded, an error signal is generated and an error output takes place. Device for carrying out the method claim 1 , with an electron gun (1) which is flanged onto a recipient (2), the axis of the electron gun (1) being displaceable in one direction, and the device having an electron collector (7) arranged under the belts (3.1, 3.2), with which the electrons (8) passing through the joint (6) can be detected, and a deflection control (11) for controlling the position of an energy transfer field, which is connected to the electron collector (7) and connected to a processor (9) of the device is, has. setup after Claim 14 , characterized in that the device has an ion collector (14) arranged above the strips (3.1, 3.2) to be welded and parallel to the electron beam (5). setup after Claim 14 or 15 , characterized in that the electron collector (7) is arranged insulated from the recipient (2) under the joint (6) and is electrically connected to the recipient (2) via a varistor (17). Setup according to one of Claims 14 until 16 , characterized in that the device has a demultiplexer (10) which is connected to the electron collector (7). Setup according to one of Claims 14 until 17 , characterized in that the deflection controller (11) and the processor (9) are connected to a CNC controller of the device and a data display (13) of the device. setup after Claim 17 , characterized in that the demultiplexer (10) is connected to a CNC controller of the device and to a data display (13) of the device. Setup according to one of Claims 14 until 19 , characterized in that the vacuum in the recipient (2) can be regulated via a valve (4) of the device.

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