DE102015219450A1 - Method and device for welding at least two metal strips - Google Patents

Abstract

The invention relates to a method for welding at least two metal strips (1, 2), in which the weld seam (4) is produced in sections. The welding current (I) during switching on during the first feed movement (A) up to a first predetermined value (I1) is successively increased at least in sections and / or at least during switching off during the first feed movement (A) to a second predetermined value (I2) gradually lowered in sections. Furthermore, the invention relates to a metal strip (1, 2), which is produced by a method of the type mentioned. Finally, the invention relates to a device (5) for carrying out said method.

Description

The invention relates to a method for welding at least two metal strips, in which the at least two metal strips are arranged in a step a) parallel to each other and in a step b) a welding current is turned on, the metal strips by means of a welding head, which with a first advancing movement along a weld is moved, welded in sections and then the welding current is switched off again. In a step c), an opposite movement to the first feed movement is carried out with the welding head and the metal strips to substantially the same distance. The steps b) and c) are repeated until the metal strips are completely welded together. In addition, the invention also relates to a metal strip which is produced by a method of the type mentioned above. Finally, the invention also relates to a device for welding at least two metal strips, comprising a welding head and means for carrying out a first advancing movement and an opposite movement with the welding head.

A method, a device and a metal strip of the above type are known in principle. For example, such a method and such a device are used to longitudinally weld metal strips together for a relatively long time, for example when the metal strips are not available or produced in the required width. In order to keep the work area small, the weld is made in sections, that is, the weld consists in the end of juxtaposed pieces or sections. The problem is that the weld is constructed inhomogeneous according to the known methods, and in particular at the ends of the individual sections relative to the rest of the weld has different structure and is also different in terms of geometric dimensions. Often it comes at the ends of the individual sections, that is, where the individual pieces of the weld adjoin one another, to broadening or "Knubbeln".

In many applications, these inhomogeneities and spreads do not interfere further. For certain applications, however, welded metal strips with very high surface quality are required, for example when they are used for the production of plate-shaped or film-like materials, in particular for films for photography, LCD screens or for artificial stone ("Engineered Stone"). In this case, a liquid or pasty material is applied to a driven / moving belt and the at least partially solidified material lifted. The surface quality of the product produced with such a metal strip depends directly on the surface quality of the metal strip.

An object of the invention is therefore to provide an improved method, an improved device and an improved metal strip. In particular, to avoid or at least reduce inhomogeneities and spreads of the weld at the ends of the individual sections / pieces.

The object of the invention is achieved with a method of the type mentioned, in which the welding current during switching on during the first feed movement to a first predetermined value at least partially successively increases and / or when switching off during the first feed movement to a second predetermined value, in particular to zero, at least in sections successively lowered.

The object of the invention is further achieved with a metal strip, which is produced by a method of the type mentioned above.

Finally, the object of the invention is also achieved with a device of the type mentioned, which has a control, which is adapted to successively increase the welding current during switching on during a first feed movement up to a first predetermined value at least in sections and / or when switching off during the first feed movement to a second predetermined value, in particular to zero, at least partially successively lower.

With the help of the proposed measures, smooth transitions between the individual sections of the weld are created, which affects the microstructure on the one hand and the geometrical dimensions on the other hand. The weld therefore essentially appears as a whole or a unit. Ideally, the boundaries between the individual sections of the weld are no longer perceptible or detectable.

In general, in addition to the successively changing or continuous sections, the current profile can also have jumps, in particular at low current values, at which no appreciable influence on the weld seam occurs. As a rule, it is expedient to increase the welding current rapidly and optionally with a step function to a value above which a significant influence on the weld takes place. Likewise, the welding current can be fast or be reduced by means of a jump function of such a value to zero.

It should be noted in principle that a successive change in the current profile or a continuous section can also be composed of smaller individual stages, in particular if a digital control or regulation is used. For the purposes of the invention, such a stage should be disregarded if the height remains below 10% of the maximum current occurring during welding. Other preferred values are less than 5% and less than 1%. In many cases, the steps predetermined by a digital control or regulation are anyway so severely ground in reality that they are in fact no longer perceptible, in particular by inductances in the welding circuit.

In general, the term "substantially" in the context of the invention means in particular a deviation of up to 10%. In particular, in view of the difference between the distance covered by the welding head and the distance covered by the metal belts during the movement opposite to the first advancing movement, the term "essentially" means a maximum deviation of 10% relative to the distance traveled by the welding head during the first advancing movement , Further preferred values are a maximum of 5% and a maximum of 2%.

Further advantageous embodiments and modifications of the invention will become apparent from the dependent claims and from the description in conjunction with the figures.

It is favorable if the distance by which the metal strips are moved in step c) is shorter by a difference distance than the distance traveled by the welding head. In this way, the adjacent portions of the weld overlap each other, and a particularly homogeneous course of the same can be realized.

It is also advantageous if the distances at which the welding current is at least partially successively increased or decreased when switching on and off, are the same length. In this way, a homogeneous course of the weld is even better realized. This is especially true when the distances at which the welding current is at least partially successively increased or decreased when switching on and / or off, in each case essentially correspond to the difference distance mentioned above.

It is furthermore advantageous if the speed of the first feed movement when the welding current is switched on is at least partially successively increased up to a third predetermined value and / or if it is switched off to a fourth predetermined value (in particular zero) is successively reduced at least in sections. As a result, another parameter for influencing the welding result is available. In particular, the variation of the feed rate is advantageous if the welding current can not be varied to the extent necessary, for example, if the method for producing the metal strip with an existing welding power source is to be performed, which does not fully meet the requirements. Like the course of the welding current, the progression of the feed speed can also have jumps.

In addition, it is favorable if the successive increase / decrease of the welding current and / or the feed rate takes place linearly, exponentially, logarithmically, along a sine half-wave or along a sine-wave quarter. As a result, particularly smooth transitions between the individual sections of the weld can be realized.

It is also particularly advantageous if the successive increase / decrease in the welding current and the feed rate take place in such a way that the energy introduced per path unit into the weld changes linearly, exponentially, logarithmically, along a sine half-wave or along a sinusoidal wave. In this variant of the manufacturing method, therefore, the course of the introduced into the weld energy is considered, which essentially results from the course of the welding current and the feed rate. A small feed rate leads to a higher energy input per unit travel than a high feed rate with the same welding current.

It is also favorable if alternating parts are superimposed on the constant values of the welding current and / or the feed rate. As a result, the welding and / or stability of the arc may be favored.

Finally, it is advantageous if the device for welding the metal strips has means for carrying out a movement of the metal strips which is opposite to the first advancing movement. In this way, the production of the metal strip can run completely automatically, and a manual advancing the metal strips can be omitted.

It should be noted at this point that the variants disclosed for the production process and the resulting advantages apply equally to the disclosed device and vice versa.

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

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

1 a schematically illustrated arrangement for welding at least two metal strips in side view;

2 the arrangement 1 in plan view;

3 as 1 but with an exemplary course of the welding current;

4 a further exemplary course for the welding current or the feed rate with step-shaped sections;

5 further exemplary profiles for welding current and feed rate;

6 an example in which alternating parts are superimposed on a constant value of the welding current / feed rate;

7 exemplary profiles for welding current, feed rate and introduced into the weld energy and

8th an exemplary device for welding two metal bands.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position. Furthermore, individual features or combinations of features from the illustrated and described different embodiments may represent for themselves, inventive or inventive solutions.

The 1 and 2 show a greatly simplified and schematically illustrated arrangement for welding at least two metal strips 1 . 2 , with the help of a welding head 3 along a weld 4 in side view ( 1 ) and plan view ( 2 ). The welding of the metal bands 1 . 2 is done in sections. Specifically, the sections or segments C1..C4 are welded successively. In a first step a) of the process carried out, the metal strips 1 . 2 aligned parallel to each other. In a further step b), a welding current I is switched on and the metal strips 1 . 2 partially welded together, the welding head 3 along the weld 4 is moved with a first feed motion A and wherein the welding current I is turned off at the end of the section C1..C4. Then, in a step c) two movements are carried out, either simultaneously or sequentially or offset in time. The metal bands 1 . 2 perform an opposite to the first feed movement A movement B, namely by the distance x. Also the welding head 3 performs an opposite movement to the first feed A motion B, where he covers a distance y, which is substantially the same length as the distance x. Steps b) and c) are carried out recursively in sequence until the metal bands 1 . 2 are completely welded together, that is, successively the sections C1..C4 are welded. The 1 2 show a state in which the portion C2 is being welded, that is, the step b) is being executed for the second time. In this way, even relatively long metal bands 1 . 2 be welded in a tight space over the entire length.

In order to create a smooth transition between the individual segments C1... C4 and thus a homogeneous strip surface, the welding current I during switching on during the first feed movement A is increased at least in sections successively at least in sections and / or when switched off during the first Feed movement A to a second predetermined value at least partially successively lowered, in particular to zero. Advantageously, the distance x to which the metal bands 1 . 2 in step c) are moved to a difference distance d is shorter than that of the welding head 3 distance traveled y, as in the 1 and 2 is shown. In this way, an overlap of the adjacent sections C1..C4 results during welding.

The 3 shows an illustrative course of the welding current I, which is successively increased at the beginning of a segment C1..C4 respectively when switching on and is successively lowered at the end of a segment C1..C4 respectively at power off. It is also conceivable to increase the current I successively only when switching on, or to reduce it successively only when switched off. At the beginning or end of the current flow would then result in a step accordingly. In the example shown, the welding current is reduced from zero linearly to a constant value and linearly from this value to zero. But this is not a mandatory condition, as in consequence still on the basis of 4 to 7 is explained.

The overlap and the successive change of the welding current I results in a particularly smooth transition between the segments C1... C4, as a result of which the reworking of the weld seam 4 can be kept low. It is advantageous if the distances z1, z2, on which the welding current I when switching on and off at least partially successively increased or decreased, as in the 3 shown, are the same length and beyond (substantially) correspond to the difference distance d, which is formed by the difference of the distances y - x. However, this is not mandatory. In principle, the distances z1 and z2 can also be of different lengths and also do not have to correspond to the difference distance d.

4 shows now a somewhat more general course of the welding current I, from which it is apparent that the welding current I is not necessarily successively increased over the entire distance z1, or must be successively lowered over the entire distance z2, but also steps, respectively jumps in the course of the current can be provided , In the concrete, purely illustrative example of 4 If the welding current I is suddenly increased to a value I3 when it is switched on, then it remains constant for a while and is then increased linearly to the value I1. When switching off the welding current I is first linearly reduced to a value I2 on the distance z2, then remains constant for a while and is then suddenly reduced to the value zero. Such a course is advantageous in that welding currents I near zero hardly affect the weld seam 4 to have. The proposed measures, however, quickly reach a level for the welding current I, in which an influence on the weld 4 is present.

In the example shown, the welding current I can be related to the path s or the time t. In particular, when the speed v of the first feed movement A is constant, a practically congruent course results. However, the speed v is not necessarily constant, but can be at least partially successively increased when turning on the welding current I up to a third predetermined value v1 and / or at least partially successively lowered when switching off to a fourth predetermined value v2. Even steps or jumps in the course of the speed are possible in principle. In the 4 an exemplary speed curve v is shown, which has the same shape as the current waveform I. However, it is noted at this point that an equality of the current waveform I with the velocity curve v of course not necessary, but sometimes they can even deviate greatly. For example, for the welding current I could be a course as in 4 represented and for the speed v a course as in 3 be provided shown.

Until now, it was assumed that linear or stepped progressions were used. However, these are by no means the only options. 5 shows further examples in which, in addition to a linear increase (solid line), also an exponential curve (dashed line), a logarithmic curve (dot-dashed line), a curve along a sine half-wave (dotted line) or along a sinusoidal wave (dash-dotted line) Point line) for the welding current I and the feed rate v are shown.

It is also conceivable that alternating parts are superimposed on the constant values of the welding current I and / or the feed rate v, as in the 6 is shown. For example, the constant value could be superimposed on a triangular course, a rectangular course or a sinusoidal course.

In a further advantageous variant, the successive increase / decrease of the welding current I and the feed rate v is carried out in such a way that the per path unit in the weld 4 introduced energy E linear, exponential, logarithmic, along a sine half-wave or along a sinusoidal wave changes. 7 shows an example in which the welding current I exponential and the feed rate v is logarithmic, whereby the energy input E in the weld 4 here linear or approximately linear.

8th finally shows an exemplary and schematically illustrated device 5 for welding at least two metal bands 1 . 2 comprising one with a welding power source 6 connected welding head 3 who is on a carriage 7 which is mounted on rails 8th is guided and by a drive 9 can be moved. The car 7 , the rails 8th and the drive 9 thus form in this example means for carrying out a first feed movement A and an opposite movement B with the welding head 3 , In addition, the device includes 5 a control / regulation 10 which is set up to at least partially successively increase the welding current I during switching on during a first feed movement A up to a first predetermined value I1 and / or at least in sections during the first feed movement A to successively lower it to a second predetermined value I2. In addition, the control / regulation 10 also with the drive 9 connected, so that both the welding current I and the feed rate v can be successively increased / decreased, whereby, for example, in the 4 to 7 Trajectories shown are feasible.

In addition, the device includes 5 also a machine table 11 and two drives 12 . 13 , which in the example shown means for carrying out a counter to the first feed movement A movement B of the metal bands 1 . 2 form. The drives 12 and 13 are also in this example with the control / regulation 10 connected, whereby the steps a) to d) comprehensive process for welding two metal strips 1 . 2 is feasible.

Generally, it should be noted that in particular for the feed rate v due to the inertia of the welding head 3 , of the carriage 7 and the drive 9 Not any courses are feasible. In particular, maximum slopes for the speed, corresponding to maximally achievable accelerations, are predetermined by the system. With the help of the proposed measures can be adjusted for the welding current I to the course of the feed rate v matching course, so that for the weld 4 gives a homogeneous appearance.

It is further noted that in particular the means 7 .. 9 for carrying out a first feed movement A may also be designed differently than indicated. For example, the welding head 3 also be attached to the arm of a Gelenkarmroboters. Also the funds 12 . 13 for the movement of the metal bands 1 . 2 Of course, they can also be designed differently.

The exemplary embodiments show possible embodiments of a production method for a metal strip 1 . 2 , It should be noted at this point that the invention is not limited to the specifically illustrated embodiments of the same / the same, but also various combinations of the individual embodiments are possible with each other and this possibility of variation due to the teaching of technical action by objective invention in the skill of technical expert working in this technical field. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection.

In particular, it is also noted that the illustrated devices may in reality also comprise more or fewer components than shown and are sometimes shown in greatly simplified form in the figures.

For the sake of the order, it should finally be pointed out that the illustrated devices as well as their components have also been shown partly out of scale and / or enlarged and / or reduced in size for a better understanding of their design.

The task underlying the independent inventive solutions can be taken from the description.

LIST OF REFERENCE NUMBERS

1

metal band

1

metal band

3

welding head

4

Weld

5

welder

6

Welding power source

7

dare

8th

rail

9

Drive for welding head

10

Control / regulation

11

machine table

12

Drive for metal band

13

Drive for metal band

A

feed motion

B

Return movement

C1..C4

welding portion

d

Differential feed path

e

energy

I

welding current

s

path

t

Time

v

speed

x

Feed path metal band

y

Feed path welding head

z1

Einschaltweg

z2

Ausschaltweg

Claims (11)

Method for welding at least two metal strips ( 1 . 2 ), comprising the steps of a) arranging the at least two metal strips in parallel ( 1 . 2 ), b) turning on a welding current (I), welding the metal strips in sections ( 1 . 2 ) by means of a welding head ( 3 ), which along a weld ( 4 ) is moved with a first advancing movement (A), and turning off the welding current (I), c) carrying out a movement (B) in the opposite direction to the first advancing movement (A) with the welding head ( 3 ) and the metal bands ( 1 . 2 ) substantially the same distance (x, y), d) repeating steps b) and c) until the metal strips ( 1 . 2 ) are completely welded together, characterized in that the welding current (I) during switching on during the first advancing movement (A) up to a first predetermined value (I1) at least partially successively increased and / or when turned off during the first advancing movement (A) a second predetermined value (I2) is at least partially successively lowered. Method according to claim 1, characterized in that the distance (x) around which the metal strips ( 1 . 2 ) are moved in step c) to a difference distance (d) is shorter than that of the welding head ( 3 ) traveled distance (y). A method according to claim 1 or 2, characterized in that the distances (z1, z2) on which the welding current (I) when switching on and off at least partially successively increased or decreased, are the same length. A method according to claim 2 and 3, characterized in that the distances (z1, z2) on which the welding current (I) when switching on and / or off at least partially successively increased or decreased, each corresponding substantially to the difference distance (d). Method according to one of claims 1 to 4, characterized in that the speed (v) of the first feed movement (A) when turning on the welding current (I) up to a third predetermined value (v1) successively increased at least in sections and / or when switching off a fourth predetermined value (v2) is lowered at least in sections successively. Method according to one of claims 1 to 5, characterized in that the successive increase / decrease of the welding current (I) and / or the feed rate (v) is linear, exponential, logarithmic, along a sine half-wave or along a sine quarter wave. Method according to one of claims 1 to 6, characterized in that the successive increase / decrease of the welding current (I) and the feed rate (v) is carried out so that the per path unit in the weld ( 4 ) introduced energy (E) linear, exponential, logarithmic, along a sinusoidal half wave or along a sinusoidal wave changes. Method according to one of claims 1 to 7, characterized in that constant values of the welding current (I1, I2) and / or the feed rate (v1, v2) alternating parts are superimposed. Metal band ( 1 . 2 ), characterized in that it is produced by a method according to one of claims 1 to 8. Contraption ( 5 ) for welding at least two metal strips ( 1 . 2 ), comprising a welding head ( 3 ) as well as funds ( 7 .. 9 ) for carrying out a first feed movement (A) and an opposite movement (B) with the welding head ( 3 ), characterized by a control / regulation ( 10 ), which is adapted to successively at least partially increase the welding current (I) during switching on during a first advancing movement (A) up to a first predetermined value (I1) and / or to a second during switching off during the first advancing movement (A) predetermined value (I2) at least partially successively lower. Contraption ( 5 ) according to claim 10, characterized by means ( 12 . 13 ) for carrying out a movement (B) of the metal bands opposite to the first advancing movement (A) ( 1 . 2 ).

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