EP2529857B1 - Method and device for producing sheet-shaped reinforcement mats - Google Patents

Description

The invention relates to a method for the production of an arcuate structural steel mat, which is formed in the plane defined by the Baustahimatke at least in one area arcuate, from a plurality of rods by welding the rods to a structure consisting of longitudinal bars and transverse bars structure, starting at a front End by welding a first transverse bar with the longitudinal bars, generating a feed for positioning the longitudinal bars for all other transverse bar welds until reaching a desired rear end, to achieve the arch shape of the steel mesh a from the sheet interior to the sheet outer towards increasing feed distance is generated, and wherein the Feed by train on at least one welded cross bar and / or longitudinal bar preferably in the region of the front end, and wherein the feed takes place by train via a pulling device which is driven in the longitudinal and transverse directions becomes. Furthermore, the invention relates to a device for producing an arcuate structural steel mat, which is arcuate in the plane defined by the construction steel mat at least in one area, and consist of longitudinal bars and transverse bars welded together, the device feeding devices for the longitudinal bars, feeding devices for the Cross bars and a welding device for welding the longitudinal bars with the transverse bars, and wherein the device further comprises a pulling device for generating a bow from the inside of the arcuate reinforcing steel mat to the arc out towards increasing feed distance, and wherein the traction device is driven by a drive device in the longitudinal direction and in the transverse direction.

Reinforced steel mats (also referred to as reinforcing mats) serve to reinforce (reinforce) concrete components. They are manufactured industrially on semi-automatic or fully automatic machines and consist of intersecting, typically corrugated steel bars, which extend in the longitudinal and transverse direction and are joined together at the intersection points by welding.

An arcuate structural steel mat is a structural steel mat which is in its plane, ie in the plane defined by the reinforcing steel mat, is formed arcuately at least in one area. This is achieved in that the distance between the welding points of two adjacent transverse bars is smaller with the longitudinal bars located inside the sheet, as the distance between the welding points of two adjacent transverse bars with the longitudinal bars lying in the sheet outer.

Such arcuate structural steel meshes are used to reinforce round, half-round or conical concrete components, e.g. used to reinforce supports for wind turbines, elements for tunneling, pipes or lighthouses.

From the WO 2010/136421 A2 It is known that arcuate structural steel mats are made in Schweißanlangen that one pushes the longitudinal bars through the welding portal, with the help of the Querstabverschweißungen are made, and at the same time generates an increasing distance from the sheet interior to the sheet outer feed path. The advancing of the longitudinal bars is usually by means of feeders or feed rollers.

This procedure for positioning the longitudinal bars for each upcoming welding cycle has several significant disadvantages: First of all, relative positioning errors between adjacent longitudinal bars can occur. Furthermore, it can come by the Nachgreifen or the slip of the feed rollers to a summation of positioning errors. These two effects lead to the fact that the arched steel mats can only be produced with a relatively large inaccuracy, which varies from mat to mat. If you want to reduce this inaccuracy, so laborious readjustments are required during the welding process of a mat, which significantly increases the production time. And finally, a conversion of the welding system on the production of a new mat type is very time-consuming, since the feed distance for each longitudinal bar must be set individually.

From the German patent application DE 3324678 A1 , which forms the basis for the preamble of claims 1 and 9, a solution is known in which the feed is not by pushing but by train. Technically this is realized by means of a swivel arm. Although this solution does not have a part of the disadvantages described, the flexibility of the production process is severely restricted by the use of a swivel arm, which is pivotably mounted about a fixed point. For example, it is not possible to change the arc radius during the manufacturing process.

The object of the present invention is to avoid the disadvantages described above and to provide a method which is improved and simplified compared with the prior art or an apparatus improved and simplified compared with the prior art for the production of curved structural steel mats.

This object is achieved by the features of the two independent claims 1 and 9.

A basic idea of the invention therefore consists in that the advancement of the longitudinal bars for the respective welding cycle takes place by pulling on at least one welded transverse bar and / or longitudinal bar, preferably in the area of the front end of the curved structural steel mat. As a result, the desired for each longitudinal bar feed path is automatically achieved, since all the longitudinal bars are connected to this at least one transverse bar and / or longitudinal bar. Relative positioning errors between adjacent longitudinal bars and / or summation errors of positioning errors are excluded so that the arcuate structural steel mesh can be made with higher accuracy. In addition, the settings for the production of a new mat type can be made faster.

Specifically, it is provided that the traction device comprises a cross slide which is arranged on a longitudinal slide, wherein both the cross slide and the longitudinal slide are driven by a drive device.

The easiest way is when the feed is done by train on the first welded cross bar.

Advantageously, the traction device, which is driven in the longitudinal and transverse directions, rotated in the plane of the structural steel mat. In a concrete exemplary embodiment, it can be provided, for example, that the pulling device comprises a rotary bar which is rotatable via a rotary drive device in the plane of the structural steel mat.

It has proved to be expedient if the at least one transverse bar and / or longitudinal bar on which or at which the train takes place can be released, for example detachably. is attached by a gripping device to the pulling device. In this case, the gripping device can be designed quite differently, e.g. with grippers, with clamping elements or - if they are magnetic steel bars - with electromagnets.

Furthermore, it is advantageous if the pulling device can be controlled via a control device. As a result, a certain once-programmed sequence of a welding process for the production of a specific type of mat can always be carried out in a reproducible manner. In addition, it is possible to more easily and quickly switch between the settings for producing various types of mats. Such a control device may be technically e.g. be realized with the help of a computer.

In a particularly advantageous embodiment of the method for producing arched building block mats, a method step is integrated, in which the sections of the longitudinal bars between a first and a second, subsequent crossbar welding after the first crossbar welding and the subsequent feed to prepare the second crossbar welding into a sheet be deformed. This method step is explained in more detail below in the description of the figures.

Furthermore, the method can be supplemented by the fact that the longitudinal and transverse bars are first unwound before the welding, for example, by means of a take-off of coils and then in a straightening or cutting machine to straightened straight bars or cut to a predetermined length. Advantageously, the longitudinal and transverse rods are unwound in each case in the longitudinal direction and the transverse rods are rotated after cutting in the transverse direction. For this purpose, for example, be provided, preferably movable over rails, transport device.

The process can also be extended to serve the production of three-dimensional truncated cone-shaped reinforcements for concrete components. Namely, this is possible by first producing an arcuate structural steel mat in the manner described and then bending it up three-dimensionally. This process step can be implemented particularly easily by means of the above-described traction device by first moving the traction device in a certain direction for producing the structural steel mat and subsequently reversing the direction of movement of the traction device to form the reinforcement, thereby bending the structural steel mat three-dimensionally. The bending can be realized technically, for example, by means of a bending device, which is preferably designed to be extendable and / or wedge-shaped.

To be particularly advantageous has been found to produce the arcuate structural steel mat first in the horizontal plane and then to pivot such that the axis of symmetry of the three-dimensional truncated cone-shaped reinforcement at the end of the above-described manufacturing process substantially in the vertical direction, i. comes to a halt.

The present invention also relates to a device for producing an arcuate structural steel mat which is arc-shaped in the plane defined by the structural steel mat, at least in one region. One of the characteristic features of this device is that in addition to feeders for the longitudinal bars, feeders for the cross bars and a welding device for welding the longitudinal bars with the crossbars also a traction device for generating a bow from the inside arcuate Baustahlmatte to the bow outer towards increasing feed distance comprises.

It is advantageous if, in addition to the structural features already mentioned above, the device also has guide devices for the longitudinal bars on one side or both sides of the welding device.

The guide devices, which are arranged on the side of the welding device, which faces the feeders for the longitudinal bars (i.e., in front of the welding line), serve to ensure that all the longitudinal bars have a certain distance from each other. For example, these guide devices can be guide rollers or guide plates. Advantageously, they can be tuned to a given Längsstabraster and / or (for the same purpose) exchange.

By means of the guide devices, which are arranged on the side of the welding device, which faces the pulling device (ie behind the welding line), the method step mentioned above, which consists of the sections of the longitudinal bars between each a first and a second, subsequent log welding after the first transverse bar weld and the subsequent feed to prepare the second cross bar weld to form an arc perform. For this purpose, it is advantageous if these guide devices can be pivoted in and / or are adjustable in the transverse direction via an actuator.

As has already been explained above, an advantageous procedure is that the longitudinal and transverse bars are first unwound from coils before the welding, for example by means of an unwinding device, and then in a straightening or straightening direction. Cutting machine to straight bars deformed and cut to a predetermined length. To the longitudinal and / or transverse bars of this straightening or. To transport the cutting machine to the welding device, the device advantageously has movable transport devices. These transport devices can be movably mounted on rails, for example.

Finally, it has been stated above that the method for the production of substantially arcuate structural steel mats can also be extended to be suitable for the production of three-dimensional truncated cone-shaped reinforcements. In this case, a procedure in which the reinforcing steel mat is first produced in the horizontal plane and then pivoted so that the axis of symmetry of the reinforcement at the end of the manufacturing process is substantially in the vertical direction, was found to be particularly advantageous. The feasibility of this procedure can for example be given by the fact that the area of the device comprising the welding device and the pulling device, is pivotally mounted.

Fig. 1

in der Draufsicht einen schematisch dargestellten Ausschnitt eines bevorzugten Ausführungsbeispiels der Einrichtung zur Herstellung bogenförmiger Baustahlmatten,

Fig. 2a - 2c

eine Abfolge dreier Zeichnungen, in denen schematisch in der Draufsicht ein Ausschnitt einer bogenförmigen Baustahlmatte im Bereich der Schweißlinie dargestellt ist,

Fig. 3

in der Draufsicht eine schematisch dargestellte Gesamtansicht des bevorzugten Ausführungsbeispiels aus Fig. 1,

Fig. 4a - 4c

in der Draufsicht drei verschiedene Ausführungsbeispiele einer bogenförmigen Baustahlmatte.

Further details and advantages of the present invention will be explained in more detail below with reference to the description of the figures with reference to the exemplary embodiments illustrated in the drawings. Showing:

Fig. 1

in the plan view a schematically illustrated section of a preferred embodiment of the device for producing curved reinforcing steel mats,

Fig. 2a - 2c

a sequence of three drawings, in which schematically in plan view a section of an arcuate structural steel mat is shown in the region of the weld line,

Fig. 3

in the plan view of a schematically illustrated overall view of the preferred embodiment Fig. 1 .

Fig. 4a - 4c

in plan view, three different embodiments of an arcuate structural steel mat.

In the Fig. 1 is a top view of a preferred embodiment of the device for producing arcuate structural steel mats 1 shown schematically. The longitudinal bars 2 are fed via a feed table 8 of the welding device 9 and welded to the transverse bars 3 to form an arcuate construction steel mat 1. The welding device 9 comprises a welding bridge with a plurality of, preferably with 12 × 3, movable multi-heads (not shown in the drawing). Right and left of the welding device 9 guide devices 10 and 11 are arranged for the longitudinal bars 2. The guide devices 10, which are located in front of the welding line, are guide rollers which serve to ensure that all the longitudinal bars are at a specific distance from one another. In the illustrated embodiment, the guide rollers are tuned to a predetermined Längsstabraster. The guide devices 11, which are located behind the welding line, serve to form the sections of the longitudinal bars 2 into a bow between a first and a second subsequent transverse bar welding after the first cross bar welding and the subsequent feed in preparation of the second cross bar welding. This process is based on the FIGS. 2a-2c explained in more detail.

• zwei Greifelemente 7, mit deren Hilfe der erste verschweißte Querstab 3' bzw. einer oder mehrerer Längsstäbe 2' im Bereich des vorderen Endes 4 der Baustahlmatte 1 an der Zugvorrichtung 6 lösbar befestigt werden,
• einen Drehbalken 24, mit dessen Hilfe das vordere Ende 4 der Matte in ihrer Ebene über eine Drehantriebsvorrichtung gedreht werden kann,
• einen Querschlitten 23, der auf einem Längsschlitten 22 angeordnet ist, wobei sowohl der Querschlitten 23 als auch der Längsschlitten 22 über eine Antriebsvorrichtung antreibbar sind und der Längsschlitten 22 entlang zweier Schienen 25 in Längsrichtung L bewegt werden kann.

As stated above, a basic idea of the invention is that the advance of the longitudinal bars 2 takes place by train for the pending welding cycle. In this case, in order to obtain the arch shape of the reinforcing steel mat 1, a feed path increasing from the inside of the sheet to the outside of the sheet must be generated. In the illustrated embodiment, the feed takes place by train via a traction device 6. This traction device 6 comprises

• two gripping elements 7, with the aid of which the first welded transverse bar 3 'or one or more longitudinal bars 2' are detachably fastened to the pulling device 6 in the region of the front end 4 of the structural steel mat 1,
• a pivot bar 24, by means of which the front end 4 of the mat can be rotated in its plane by means of a rotary drive device,
• a cross slide 23, which is arranged on a longitudinal slide 22, wherein both the cross slide 23 and the longitudinal slide 22 are driven by a drive device and the longitudinal slide 22 along two rails 25 in the longitudinal direction L can be moved.

The longitudinal direction L and the transverse direction Q are marked in the drawing by means of two arrows. It should be noted that the contours of the components in the area of the welding device 9 are shown projected onto a plane for better illustration, but are only partially visible in reality in plan view.

For the production of the arched reinforcing steel mat 1, the following is used in the illustrated embodiment: First, a plurality of longitudinal bars 2 are fed to the welding device 9. Subsequently, a first transverse bar 3 'is welded to the longitudinal bars 2. Thereafter, this first welded transverse bar 3 'is releasably secured to the pulling device 6 by means of the gripping devices 7, so that the longitudinal bars 2 can be collectively positioned stepwise by means of the pulling device 6 for all subsequent cross bar weldings. In this case, the longitudinal slide 22 moves to the right, the cross slide 23 down and the rotary bar 24 is rotated clockwise. In this way, a feed path increasing from the inside of the sheet to the outside of the sheet is generated. In each case following a feed step, the sections of the longitudinal bars 2 between a first and a second, subsequent cross-bar welding after the first transverse bar welding and the subsequent feed to prepare the second transverse bar welding are deformed into an arc.

This process is based on the FIGS. 2a and 2b explained in more detail below, wherein in these figures, only a small section of the sheet mat in the region of the weld line is shown. The longitudinal bars 2 are fed via the guide rollers 10 of the welding device 9 (which can not be seen in these figures) until they have reached the position Pos. 1. At this point, the longitudinal bars 2 are welded to a first transverse bar 3 at the points 27. Subsequently, the longitudinal bars 2 (by train) a piece in the direction of in the Fig. 2a to be seen arrow continues to move until the first cross bar 3 is in position Pos. 2. The sections 28 of the longitudinal bars 2, which are located between the guide rollers 10 and the transverse bar position Pos. 2, initially formed as a straight chord. In a second step, in the Fig. 2b is indicated schematically, the guide device 11 is pivoted after the feed to the reinforcing steel mat. There it hooks behind an outer longitudinal rod portion and is then moved over an actuator a piece in the direction of the arrow, that is substantially perpendicular to the longitudinal bar sections 28. As a result, this outer longitudinal bar portion and thus at the same time all other longitudinal bar sections pulled so far outward until the longitudinal bars 2 have reached the transverse bar position Pos. 1 desired for the subsequent transverse bar welding desired positions in the transverse direction. In this way, the first formed as a straight chords sections 28 of the longitudinal bars 2, which are located between the guide rollers 10 and the cross bar position pos. 2, each deformed into an arc. Following this process step, the welding of a next transverse bar 3 takes place (cf. Fig. 2c ).

In the Fig. 3 is an overall view of the in Fig. 1 shown preferred embodiment of the device for producing curved reinforcing steel mats 1 to see. It should be noted in advance that, as with the other figures, it is a schematic representation, ie that technical details that are not important to the basic understanding have been omitted. Right above eight coils 20 are indicated, which are located in a unwinding device 12. On these coils 20, the rods are wound, from which the reinforcing steel mat 1 is welded together, that is, that these rods are first unwound and fed to a straightening or cutting machine 13. Here they are first deformed into straight bars, cut to a predetermined length and finally placed on a bar outlet beam 14. The part of the rods, which is provided as longitudinal bars, is subsequently moved in the direction of the arrow by means of a transport device 15 movable over rails 16, transferred to a transfer device 17 and subsequently fed to the welding device 9 to the right by means of this transfer device 17. The part of the cut rods provided as crossbars is likewise fed to the welding device 9 in a corresponding manner by means of a transport device 18 which moves along two rails 19. Of course, these cross bars, so that they show Q in the transverse direction, must be rotated by 90 ° during this transport process. Therefore, the rails 19 have a 90 ° curve on. The transport device 18 for the transverse rods is guided below the feed table 8 for the longitudinal bars to the welding device 9. The end positions of the transport devices 15 and 18 and the transfer device 17 are shown in dashed lines. It should also be noted that the transfer device 17 is movably mounted between two guide rails 29.

Using the in the Fig. 3 illustrated device, it is also possible to produce three-dimensional truncated cone-shaped reinforcements for concrete components. For this purpose, first an arcuate structural steel mat 1 in the horizontal plane, ie produced in the drawing plane. During the manufacture of the reinforcing mat 1, the pulling device 6 moves to the right. Following the last transverse bar welding, the direction of movement of the pulling device 6 is then reversed, ie, the entire mat 1 is pushed back to the left while being three-dimensionally arranged by wedge-shaped bending elements arranged in the area of the feed table 8 (not shown in the drawing) is bent. At the same time, the entire region 26 of the device comprising the welding device 9 and the pulling device 6 is pivoted by 90 ° so that the axis of symmetry of the reinforcement at the end of the production process is substantially in the vertical direction.

The Fig. 4a, 4b and 4c show three different embodiments of arcuate structural steel mats 1, which can be produced by the method or by means of the device. For example, mats with different radii of curvature, mats that are curved in only one area or mats can be made in different widths and lengths. In addition, mild steel mats 1 can be produced with different crossbar or longitudinal bar spacing. The distance between the transverse rods 3 can be varied via a feed of different strengths, whereas the distance between the longitudinal rods 2 can be varied by an adjustment or an exchange of the guide rollers 10.

LIST OF REFERENCE NUMBERS

1

arched reinforcing steel mat

2, 2 '

longitudinal bars

3, 3 '

crossbars

4

front end of the arched structural steel mat

5

rear end of the arched structural steel mat

6

hitch

7

gripping device

8th

Feed table for the longitudinal bars

9

welder

10

Guide rollers in front of the welding line

11

Guiding devices behind the welding line

12

unwinding

13

Straightening or cutting machine

14

Staff outlet bar

15

Transport device for the longitudinal bars

16

Rails for the transport device for the longitudinal bars

17

Transfer device for the longitudinal bars

18

Transport device for the cross bars

19

Rails for the transport device for the cross bars

20

Do the washing up

21

Truncated cone-shaped reinforcement

22

longitudinal slide

23

cross slide

24

bogie beam

25

Rails for the longitudinal slide

26

pivotally mounted area

27

welding locations

28

Longitudinal bar sections

29

Guide rails for the transfer device

Q

transversely

L

longitudinal direction

Pos. 1, 2

Positions of a longitudinal bar

Claims (19)

1. A process for the production of a structural steel mat (1) which is of an arcuate configuration at least in a region in the plane defined by the structural steel mat (1) at least in a region, from a plurality of bars by welding of the bars to give a structure comprising longitudinal bars (2) and transverse bars (3), beginning at a front end (4) by welding a first transverse bar (3') to the longitudinal bars (2), producing an advance movement to position the longitudinal bars (2) for all further transverse bar welding operations until reaching a desired rear end (5), wherein to achieve the arcuate shape of the structural steel mat (1) an advance path which increases from the arc interior to the arc exterior is produced, and wherein the advance movement is effected by pulling on at least one welded transverse bar (3') and/or longitudinal bar (2'), preferably in the region of the front end (4), and wherein the advance movement is effected by pulling by way of a pulling device (6) driven in the longitudinal direction (L) and transverse direction (Q), characterised in that the pulling device (6) includes a transverse carriage (23) arranged on a longitudinal carriage (22), wherein both the transverse carriage (23) and also the longitudinal carriage (22) are driven by way of a drive device.
2. A process according to claim 1 characterised in that the advance movement is effected by pulling on the first welded transverse bar (3').
3. A method according to claim 1 or claim 2 characterised in that the advance movement is effected by pulling by way of a pulling device (6) which is rotated in the plane of the structural steel mat (1).
4. A process according to one of claims 1 to 3 characterised in that the at least one transverse bar (3') and/or longitudinal bar (2') at which the pulling action is implemented is releasably fixed to the pulling device (6).
5. A process according to one of claims 1 to 4 characterised in that the portions (28) of the longitudinal bars (2) are deformed to provide an arc between a respective first and a second subsequent transverse bar welding operation after the first transverse bar welding operation and the subsequent advance movement to prepare for the second transverse bar welding operation.
6. A process according to one of claims 1 to 5 characterised in that prior to the welding operation the longitudinal bars (2) and the transverse bars (3) are firstly unwound from coils (20), then shaped to provide straight bars and finally cut to size at a predetermined length, wherein the longitudinal bars (2) and transverse bars (3) are preferably respectively unwound in the longitudinal direction (L) and the transverse bars (3) are rotated after being cut to size in the transverse direction (Q).
7. A process for producing a three-dimensional reinforcement (21) in the shape of a truncated cone for precast concrete components, characterised in that the reinforcement (21) is formed by bending a substantially arcuate structural steel mat (1), wherein the structural steel mat (1) is produced according to a process according to one of claims 1 to 6.
8. A process according to claim 7 characterised in that the pulling device (6) for production of the structural steel mat (1) firstly moves in one direction and then to provide the reinforcement (21) moves in an opposite direction and in that case the structural steel mat (1) is three-dimensionally bent, wherein the structural steel mat (1) is firstly produced in a horizontal plane and is then pivoted in such a way that the axis of symmetry (S) of the reinforcement (21) at the end of the production process points substantially in a vertical direction.
9. Apparatus for the production of a structural steel mat (1) which is of an arcuate configuration at least in a region in the plane defined by the structural steel mat (1) and which comprises longitudinal bars (2) and transverse bars (3) which are welded together, wherein the apparatus includes feed devices (8, 15, 16, 17) for the longitudinal bars (2), feed devices (18, 19) for the transverse bars (3), and a welding device (9) for welding the longitudinal bars (2) to the transverse bars (3), and wherein the apparatus further includes a pulling device (6) for producing an advance path which increases from the arc interior of the arcuate structural steel mat (1) towards the arc exterior and wherein the pulling device (6) is drivable by way of the drive device in the longitudinal direction (L) and in the transverse direction (Q), characterised in that the pulling device (6) includes a transverse carriage (23) arranged on a longitudinal carriage (22), wherein both the transverse carriage (23) and also the longitudinal carriage (22) are drivable by way of a drive device.
10. Apparatus according to claim 9 characterised in that the pulling device (6) is controllable by way of a control device.
11. Apparatus according to claim 9 or claim 10 characterised in that the pulling device (6) is rotatable by way of a rotary drive device in the plane of the structural steel mat (1), wherein the pulling device (6) preferably includes a rotary beam (24) which is rotatable by way of a rotary drive device in the plane of the structural steel mat (1).
12. Apparatus according to one of claims 9 to 11 characterised in that the pulling device (6) includes at least one gripping device (7).
13. Apparatus according to one of claims 9 to 12 characterised in that guide devices (10, 11) for the longitudinal bars (2) are arranged on one side or both sides of the welding device (9), wherein the guide devices (10) arranged on the side of the welding device (9), that is towards the feed devices (8, 15, 16, 17) for the longitudinal bars (2), preferably involve guide rollers.
14. Apparatus according to claim 13 characterised in that the guide devices (10) arranged on the side of the welding device (9), that is towards the feed devices (8, 15, 16, 17) for the longitudinal bars (2), can be matched to a predetermined longitudinal bar grid pattern and/or are interchangeable.
15. Apparatus according to claim 13 or claim 14 characterised in that the guide devices (11) arranged on the side of the welding device (9), that is towards the pulling device (6), are adapted to be pivotable in and/or are displaceable in the transverse direction (Q) by a control drive.
16. Apparatus according to one of claims 9 to 15 characterised in that the apparatus includes an unwinding device (12) for coils (20) on which the longitudinal bars (2) and the transverse bars (3) are wound, and/or a straightening or cutting machine (13).
17. Apparatus according to one of claims 9 to 16 characterised in that the feed devices (8, 15, 16, 17) for the longitudinal bars (2) and/or the feed devices (18, 19) for the transverse bars (3) include transport devices (15, 18) which are displaceable preferably by way of rails (16, 19),
18. Apparatus according to one of claims 9 to 17 characterised in that a bending-up device is arranged in the region of the feed devices (8, 15, 16, 17) for the longitudinal bars (2), wherein the bending-up device is preferably extendable and/or is of a wedge-shaped configuration.
19. Apparatus according to one of claims 9 to 18 characterised in that the region (26) of the apparatus, that includes the welding device (9) and the pulling device (6), is mounted pivotably.

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