EP1089835B1 - Method and device for producing straight bead welded pipes from flat sheet metal blanks - Google Patents

Abstract

An apparatus to produce straight bead welded tubes from flat sheet metal blanks with two parallel longitudinal edges includes two form tool halves. The two form tool halves have outer cylindrical half shells borne by a tool support, and are disposed laterally inverted in relation to one another. They are moved towards one another and out of an opened receiving position for the sheet metal blanks into a closed position, in which the two longitudinal edges are held together by the two form tool halves. The apparatus also includes a welding device, which moves over the two form tool halves along the two longitudinal edges retained in a welding position. The two form tool halves have cylindrical internal mandrel halves which are fixedly associated with the outer cylindrical half shells and which cooperate with the outer cylindrical half shells to produce form gaps for insertion of the sheet metal blanks.

Description

There are various methods and devices for Manufacture of longitudinally welded tubes from strips and sheet metal cuts known, but none economical production of pipes short length (for example l = 3,000 mm), small Diameter (for example d = 50 mm) and relatively large Wall thickness (for example s = 2.5 mm) in medium Enable quantities. The aim of the invention is therefore, a method and an apparatus for the To create manufacture of such pipes.

In the known method of roll forming (US-A-2,110,378) a band is arranged in several one after the other Steps from driven profiled rollers to one Slotted tube formed, which is then welded. The investment for a suitable system is very high, so it is not for manufacturing of medium-sized pipes.

In the known 3-roll bending, a flat one is used Sheet metal cutting with two backup rolls around a work roll bent around. With such a procedure can be Pipes with a wall thickness of, for example, 1.0 mm and a diameter of 50 mm only with a length of less than Manufacture 2,000 mm because the support rollers because of the deflect large supporting forces to be applied. in addition comes that the manufactured slit tube of the device removed and longitudinally welded elsewhere must become.

Furthermore, a clamping and holding device for Slotted tubes of relatively short length are known (DE 44 32 674 C1), in which the slotted tube of it partially wrapping bands in a suitable Welding position for a along the joint gap movable welding device is held. To become one so it comes to longitudinally welded pipe required one in a separate device Form sheet metal blank into a slotted tube.

In another known device (DE-PS 966 111) for the manufacture of longitudinally welded pipes flat sheet metal blanks with parallel longitudinal edges the sheet metal blank in one and the same device for Slotted tube formed and by the tube forming Medium with the longitudinal edges to be welded in Welding position maintained. Two from a tool carrier worn, mutually movable, mirror image mutually arranged and outer cylindrical Half-shell mold halves take in the sheet metal blank in its open recording position its two long edges. When moving the Half of the mold will be cut to the sheet metal both ends held fixed in the middle, so that the sheet metal blank on both sides of the cylindrical Half shells along until its long edges in Vertex meet. In this position the sheet metal blank formed into a slotted tube held. Then the longitudinal edges together can weld the top ends of the Mold halves are opened so that the Joining gap is released. A major disadvantage such a device is that the danger there is that the sheet metal blank due to lack of internal and outer guide buckles. This danger is special large for thin-walled sheet metal blanks.

In a very similar known device for Forming sheet metal blanks into tubes and subsequent welding (DE-PS 593 622) both mold halves are not cylindrical Half shells, but with axially offset disks arcuate cutouts formed. With this Device is said to be a conical from a sheet metal blank Tube are formed. That is why the circular arc Cutouts of the washers in the axial direction increasing radius. In this known device however, in contrast to the other previously described known device the outer parts of the Mold halves an inner tapered mandrel assigned. However, this thorn is not during the effective throughout the molding process, but only at the end of the Molding process because it is in the middle between the Mold halves is placed on the sheet. Because of the lack of inner and outer guidance during the Despite such a thorn, the forming process becomes a danger the buckling of the sheet metal blank during the Form process not encountered.

The invention has for its object a method and to create a device that allow it to Sheet metal blanks, especially those with thin ones Wall thickness to produce longitudinally welded pipes. In particular, the method and the device for Processing of sheet metal blanks of various thicknesses, for example tailored blanks.

The invention thus proceeds from a method for Manufacture of a longitudinally welded tube from one flat sheet metal cut with parallel longitudinal edges, at which the sheet metal cutting with the help of two against each other movable, mirror images arranged to each other, having outer cylindrical half-shells Mold halves is formed into a slotted tube and then the longitudinal edges in the apex of the Molding tool are welded together, being held in position by the mold halves (see e.g. DE-C-966 111). at Such a method according to the invention Sheet metal cutting when molding through inner cylindrical Mandrel halves that fix the outer half shells are assigned and form columns with these, supported on the inside, with the one in the apex emerging longitudinal edges free for welding being held.

The invention further relates to a device for Manufacture of longitudinally welded tubes from flat Sheet metal cuts with parallel longitudinal edges with two of a tool carrier, against each other movable, arranged in mirror image to each other and having outer cylindrical half-shells Mold halves emerging from an open Pick-up position for cutting the sheet into a closed position are movable, in which the longitudinal edges to be welded together from the closed mold halves in the upper Vertex are held together, and with an over the mold halves along in the welding position held longitudinal edges movable welding device (see e.g. DE-C-966 111).

With such a device, the invention is thereby characterized in that the mold halves the outer Half-shells fixedly assigned cylindrical inner mandrel halves have, with the outer half-shells for form the sheet metal blank to be inserted, the Form column in the closed position of the Mold halves emerging from the form gaps in the crown Keep longitudinal edges free for welding.

With the inventive method and Device according to the invention can be sheet metal blanks different thickness to a cylindrical tube reshape without the risk that the Forming process, the blank folds out. In particular tubes can be made from sheet metal blanks according to the invention short length in medium quantities economically produce. Both pipes with constant Produce wall thickness as well as pipes that have a different over their length or circumference Have wall thickness. The particular advantage of the invention is that the mold halves themselves shaped slot tube with the joint gap in an optimal Hold the welding position around the weld with the lengthways of the joining gap movable welding device manufacture. So there are no longer two separate ones Devices for reshaping and holding the Slot tube required in welding position. In order to there is also no labor-intensive reloading of the Slot tube with the then required alignment and Tighten.

According to a first embodiment of the invention provided that the sheet metal blank first with a Half all in one of the slots and then with his the other half inserted into the other slot becomes. One of the two mold halves, especially the movable one, near the entrance of the mold gap have an abutment on which at Moving the mold halves together a longitudinal edge the sheet metal blank can be supported. So that will Sheet metal cutting given a good guide that a Misalignment of the sheet metal blank when inserted in excludes the form gap.

To improve the geometry of the joint gap, the Sheet metal cutting in those adjacent to the longitudinal edges narrow streaks at the exit or after the exit are reshaped from the mold gaps in such a way that they merge essentially tangentially. In terms of device, this can be done in two ways and Realize wise. Either is the top one Vertex area of the mold halves on the Longitudinal edges in the sense of bringing them together Tool assigned or the form column run to top vertex in a common plane.

The desired spatial fixation of the inner mandrel halves in the outer half shells with the possibility of the To be able to remove the shaped tube can realized further embodiment of the invention be that the outer half-shells and the Inner mandrel halves of each mold half on one their ends are connected and the Inner mandrel half with its other end immediately on Tool carrier is releasably set while the Internal mandrel halves in the rest of several support members in Position held by the outer half-shell Reach through recesses and a sliding coupling on the inner half of the mandrel towards the apex of the outer half shell can be uncoupled. At this Design results in a rigid assignment of Half-shell and half-mandrel also on parts of the Length of the inner mandrel half.

This configuration can be individually constructively realize that the outer half-shell and the inner mandrel half connected at one end in this connection section lie against each other without gaps and held together by releasable clamping elements. This results in a very precise assignment of the half-shell and inner mandrel half with easy installation options. The Detachable clamping elements allow the form gap to be somewhat to open the finished pipe from the mold pull out or even around the inner mandrel halves pull out the finished pipe.

To do this with the front end of the inner mandrel half loosened To be able to pull the pipe out of the mold without that the inner mandrel half by resting on the tube Difficult to pull out, provides an embodiment that the inner mandrel half opposite the outer half shell protrudes the connected end and the above piece is assigned a pressure element with which on the Inside mandrel half a swivel moment around a horizontal Transverse axis in the sense of relieving the front end the inner mandrel half can be applied.

To prevent the sheet metal blank from buckling, if the sheet metal blank is inserted into the mold gap, it is envisaged that immediately below and in the Pick-up position between the mold halves height-adjustable support structure for the in the Form gap to be introduced sheet metal blank is provided. This support structure preferably faces the entrance of each mold gap over the entire length of the mold gap and in the direction of travel Mold halves resiliently supported baffle. These baffles retreat when the Mold halves at the end of the molding in the closed position.

The exact positioning of the longitudinal edges in the upper one Vertex of the mold halves for the Longitudinal seam welding can be done with simple means guarantee. According to one embodiment, the Invention provided that one of the two Mold halves, especially the stationary, in top vertex a retractable stop for the longitudinal edge of the in this mold half deformed sheet metal blank is assigned. This The stop then also serves as a support when inserting of the sheet metal blank in the mold gap of the others Mold half. The stop preferably has one such asymmetrically formed tip that at Impact of the other longitudinal edge on this stop this recedes with the release of one longitudinal edge, both longitudinal edges meet and so one Form butt joint.

To prevent welding Dirt, such as melt spatter or smoke (for example evaporated zinc in the case of galvanized sheets) the molding tool is dirty, according to one embodiment of the invention provided in the area of the upper vertex of the Arrange a drip tray inside the mandrel halves. A Such a collecting tray can be used after each use Welding device to be cleaned or replaced.

The collecting tray is preferably arranged stationary and extends the entire length of the Mold halves. With such a configuration be further provided that they are close to the Inner mandrel halves are connected and with the free Longitudinal edge areas of the tube forms a channel. On such a channel is suitable for a protective gas purging or Extraction of the fumes generated during welding.

The drip tray itself expediently consists of flexible material and has a V-shaped cross section. This configuration is particularly suitable because it can be easily connected to the mandrel halves and not moving the mold halves together hampers, but folds together.

Alternatively, the drip tray can also be used with the Welding device be designed to migrate. That leaves can be realized constructively easily if it is provided that it is on the end face of a plunger Pushing out the inner mandrel halves is kept.

Figur 1

eine Vorrichtung zum Herstellen von längsnahtgeschweißten Rohren aus ebenen Blechzuschnitten in perspektivischer Darstellung,

Figur 2

die Vorrichtung gemäß Figur 1 in einem vergrößerten Ausschnitt von der Vorderseite gesehen in perspektivischer Darstellung,

Figur 3

die Vorrichtung gemäß Figur 1 in Vorderansicht,

Figur 4

die Vorrichtung gemäß Figur 1 in einem vergrößerten Ausschnitt von der Rückseite gesehen in perspektivischer Darstellung,

Figur 5

die Vorrichtung gemäß Figur 1 in einem vergrößerten Ausschnitt und aus einer anderen Perspektive als Figur 4 von der Rückseite aus gesehen in perspektivischer Darstellung,

Figur 6

zwei Formwerkzeughälften der Vorrichtung gemäß Figur 1 in Vorderansicht und in vereinfachter Darstellung

und

Figur 7

eine Formwerkzeughälfte der Figur 6 in Vorderansicht mit zusätzlichen Details.

The invention is explained in more detail below with reference to a drawing which shows an exemplary embodiment. In detail show:

Figure 1

a device for producing longitudinally welded tubes from flat sheet metal blanks in a perspective view,

Figure 2

2 shows the device according to FIG. 1 in an enlarged detail seen from the front in a perspective view,

Figure 3

2 the device according to FIG. 1 in front view,

Figure 4

1 shows the device according to FIG. 1 in an enlarged detail from the rear in a perspective view,

Figure 5

1 in an enlarged detail and from a different perspective than FIG. 4 seen from the rear in a perspective view,

Figure 6

two mold halves of the device according to Figure 1 in front view and in a simplified representation

and

Figure 7

a mold half of Figure 6 in front view with additional details.

A mold is on a tool carrier 1 constructed, which consists of two mold halves 2,3. Above the mold halves 2, 3 is by means of a trolley 4 a welding device 5 for longitudinal seam welding traversable. While the mold half 2 stationary is arranged on the tool carrier 1, the Mold half 3 mounted on linear guides 6 and by means of actuating cylinders 7 in the direction of the other Mold half 2 movable.

The mold halves 2, 3 have essentially that same structure. They consist of an outer cylindrical half-shell 8, which extends in the longitudinal direction composed of individual sections and one in it fixed to form a gap 9 Inner mandrel half 10. At the front end (see Figure 2) the inner mandrel half 10 by means of a swivel arm 11 held on a front pin 11a Internal mandrel half 10 attacks. The inner mandrel half 10 has at the back end (see. Figures 4,5) an im Outer diameter enlarged section 10a, the is equal to the inner diameter of the half-shell 8. With the inner mandrel half 10 lies firmly against this section 10a the half shell 8. Section 10a faces the half shell 8 axially with a piece 10b. At the Section 10a in this piece 10b grip releasably Tension elements 12 on, which can be coupled by means of clamping pins 13 radially outwards and thus against the half-shell 8 can be pulled. On the protruding piece 10b can by means of a swivel arm 14 and a Actuating cylinder 15 a pivoting moment around a horizontal axis extending transversely to the longitudinal direction. The function will later be related to the Removal of a finished pipe still received.

So that the mandrel halves 10 in the area between their Ends are supported in the radial direction, attack to them support members 16 which are part of a comb 17. These support members 16 pass through recesses 8a in Form of slots in the half-shell 8 and are over Sliding clutches consisting of a cylindrical projection 16a and a corresponding recess 10e in the Internal mandrel halves 10 exist on the inner mandrel half 10 hitched. By moving in the direction of arrow P1 they can be uncoupled from the inner mandrel halves 10. This is necessary so that the support members 16 the Form gap 9 when inserting a sheet metal blank B do not block. Alternatively, the fixation of the Inner mandrel half 10 also through the half shell 8 more or less radially penetrating fixing pins can be realized that are transverse to the longitudinal axis of the mold are movable and provided in the inner mandrel halves Engage recesses. This will make the inner mandrel half 10 axially and radially supported and fixed. Preferably are the fixing mandrels at an angle of approx. 45 ° to vertical plane of symmetry.

Under the two mold halves 2,3 and opened state between them is one Support structure 18 for the sheet metal blank to be formed B provided. This support structure 18 serves the Record sheet metal cut B and a buckling after below during insertion into the mold gap 9 prevent. The support structure 18 consists in detail of several parallel to each other and across Longitudinal direction of the device stationary on the Tool carrier 1 arranged carriers 19 and on each Forming gap arranged baffles 20,21 by resilient supported guides 22,23 are worn. At the Support moving the mold halves 2, 3 together the guide plates 20, 21 the insertion of the sheet metal blank B into the form column 9, with a buckling of the with his Dead weight resting on the supports 19 Sheet metal blank B is prevented by the carrier 19. They give way because of the resilient support of the guide plates at the end of this forming process so that the Mold halves 2, 3 completely moved together can be.

The inner mandrel half 10 (see FIGS. 6, 7) of one Mold half 3 has one on the lower vertex Projection 24 and above an abutment 24a. Thereon and this is supported by a longitudinal edge of the Sheet metal blank B when it is introduced into the mold gap 9 of the other mold half 2.

The mold half 2 is in its upper apex in the direction of arrows P2, P3 movable stop 25 with assigned an asymmetrical tip 26 such that the sheet metal blank B inserted into the gap 9 with its longitudinal edge on the vertical flank of the stop 25, ie above a short slope 26a, strikes. An opposite cutting edge 26b is much longer and is in the area of the exit of the other mold gap 9, so that the emerging here Sheet metal cut with its longitudinal edge on the slope 26b incident.

The half-shell 8 and the inner mandrel half 10 can Apex in horizontal sections 8b, 10c leak. This configuration serves the Longitudinal edges in an even better position for that Bring welding. Alternatively, however, the Carriage 4 have a pressure roller 27, the Welding device 5 is arranged upstream and the longitudinal edges depressing.

As shown in Figure 6, the top is Vertex area of the mold halves 2,3 a stationary collecting tray 30 arranged as a V-shaped Profile with angled ends is formed with which they on the sections 10c rests. This drip tray 30 is flexible, in particular, it is made of sheet metal, so that it Moving the mold halves together 2.3 can be folded together. It extends over the entire length of the mold halves 2, 3 and serves to Collect waste materials generated during welding. she forms with the merged ends of the from the Sheet metal blank 13 shaped tube for a channel 30a a protective gas purge or can serve as a suction channel.

An alternative embodiment for the is not shown Drip tray. In this alternative version is a shell running with the welding device 5 intended. This bowl can be on the forehead of a pestle be arranged with the inner arbors 10 accordingly the progress of the weld are pushed out.

For sheet metal blanks of different thickness, so-called tailored blanks, in particular to form sheet metal blanks, those made of welded sheets of different Thickness exist, the mold gap has either in A circumferential direction or in the longitudinal direction accordingly the different thickness of the sheet Wide. With sheet metal cuts with low Thickness differences of up to approx. 0.1 mm can Form gap have a constant width because these are small Thickness differences in the range in each case provided oversize of the mold gap.

The operation of the device according to the invention is the following: As shown in Figure 3, is in the open Forming tool halves 2,3 with a sheet metal blank B. parallel longitudinal edges on the supporting structure 18 hung up. With the right longitudinal edge in the drawing the sheet metal blank B in the gap 9 of the Mold half 2 threaded. The left long edge is on the approach 24 of the inner mandrel half 10 of the other Mold half 3 placed so that the Sheet metal blank B with this longitudinal edge on the abutment 24a supports. The abutment 24a offers that Sheet blank B precise guidance, so that the Sheet metal blank B in the form gap 9 can not tilt. Now the mold half 3 in the direction of Move mold half 2. The Sheet metal blank B inserted into the gap 9 until its right longitudinal edge is near the support members 16 is located. Then the support members 16 on the Pulling clutches pulled so that the gap 9th is fully released. Then the Push sheet blank B further until the Longitudinal edge at the stop 25, namely at the vertical flank, as shown in Figures 6,7 is made clear. Since no force in the direction of arrow P2 acts, the stop 25 remains in the illustrated Position.

Then the mold half 3 becomes a little retracted until the left longitudinal edge is supported on the approach 24 no longer exists. The sheet metal blank B is then with its left longitudinal edge in the mold gap 9 of the mold half 3 and the Mold half 3 in the direction of mold half 2 method. Removing the support members of the Inner mandrel half is done in the same way as the right half of mandrel. As soon as the sheet metal blank B with its left longitudinal edge leaves the gap 9 and on hits the stop 25, namely on the slope 26b, the stop 25 through the longitudinal edge in Arrow direction P2 moved upwards. With this movement the right longitudinal edge also reaches the slope 26a and is released so that the next Push the longitudinal edges together exactly in the desired one Meet welding position. Then the Stop 25 by means not shown from the Area of the apex removed and the joint gap for the Longitudinal seam welding released. If necessary, you can the sheet edges by pressing means before welding be reshaped to the springing of the sheet metal edges to compensate for the elasticity of the material and to obtain a parallel joint gap.

However, before it starts to move together, the formed as a V-shaped collecting tray 30 with their outward-facing folded edges on the laid flat areas 10c and so of the Inner mandrel halves 10 worn. After another Moving together, the collecting tray 30 folds further together. It forms with the freely protruding ones Edge areas of the formed from the sheet metal blank B. Rohres a channel through which protective gas are passed can or can be conducted over the steam.

Around the longitudinally welded tube from the device there are two ways to extract. In each Case, however, the pivot cylinder 11 will first loosened front end. At the rear end is also the Tension released by pulling up the bolts 13. Then the mold half 3 is retracted a little.

After the first alternatives, after removing the Tension members 12 pulled out the inner mandrel halves 10 become. This is possible because it is in the horizontal plane have clearance between them in the radial direction. After second alternatives are the mandrel halves 10 in place. So that the front end of the Inner mandrel halves 10 but not on the tube and a pulling out of the tube hampers it on be ventilated somewhat at the front end that on the protruding piece 10b by means of the swivel arm 14 and the Actuating cylinder 15 is exerted a pivoting moment. In In both cases, the tube can then be driven 28, which is carried by the carriage 4, from the half-shells 8 be pushed out.

The particular advantages of the invention are that it is possible with her in a comparatively simple designed device sheet metal blanks for pipes short Reshape length and in the clamping that the Given sheet metal blanks through the mold halves is welded longitudinally without readjustment.

Claims (21)

1. A process for the production of a straight bead welded tube from a flat sheet metal blank having parallel longitudinal edges, wherein the sheet metal blank (B) is shaped into a slotted tube by means of two form tool halves (2,3) having outer cylindrical half shells (8) and disposed laterally inverted in relation to one another which can be moved towards one another, whereafter the longitudinal edges are welded to one another at the top of the form tool, being retained in position by the form tool halves (2,3),
   characterized in that during shaping the sheet metal blank (B) is borne on the inside by internal cylindrical mandrel halves (10) which are associated fixed with the outer half shells (8) and co-operate therewith to produce form gaps (9), the longitudinal edges emerging at the top being retained exposed for welding.
2. A method according to claim 1,
   characterized in that the sheet metal blank (B) is first pushed by one half completely into one of the form gaps (9) and then by its other half into the other form gap.
3. A process according to claims 1 or 2,
   characterized in that during or after its emergence from the form gap (9) the sheet metal blank (B) is so after-shaped in narrow strips adjoining the longitudinal edges that they merge substantially tangentially into one another.
4. An apparatus for the production of straight bead welded tubes from flat metal blanks with parallel longitudinal edges having form tool halves (2, 3) having outer cylindrical half shells and disposed laterally inverted in relation to one another which are borne by a tool support (1) and can be moved towards one another and can be moved out of an opened receiving position for the sheet metal blank (B) into a closed position, in which the longitudinal edges to be welded to one another are held together by the closed tool halves (2, 3) at their top point, the device also having a welding device (5) which can be moved over the form tool halves (2, 3) along the longitudinal edges retained in the welding position,
   characterised in that the form tool halves (2, 3) have cylindrical internal mandrel halves (10) which are associated fixed with the outer half shells (8) and which co-operate with the outer half shells (8) to produce form gaps (9) for the sheet metal blank (B) to be inserted, while in the closed position of the form tool halves (2, 3) the form gaps (9) retain the longitudinal edges emerging therefrom at the top exposed for welding.
5. An apparatus according to claim 4,
   characterised in that one of the two form tool halves (3), more particularly the movable one, has adjacent the entry to the form gap (9) an abutment (24, 24a) against which one longitudinal edge of the sheet metal blank (B) can bear when the form tool halves (2, 3) are moved together.
6. An apparatus according to claims 4 or 5,
   characterised in that the outer half shell (8) and the internal mandrel half (10) of each form tool half (2, 3) are connected to one another at one of their ends, and the internal mandrel half (10) is releasably located by its other end directly on the tool support (1), the internal mandrel half being otherwise retained in position by a number of supporting members (16) which extend through the outer half shell (8) via recesses (8a) and can be uncoupled via sliding couplings (10c, 16a) on the internal mandrel half (10) in the direction of the outer half shell (8).
7. An apparatus according to claim 6,
   characterised in that the outer half shell (8) and the internal mandrel half (10) connected thereto at one end bear against one another without a gap in this connecting portion (10a) and are held together by releasable clamping elements (12).
8. An apparatus according to claim 7,
   characterised in that the internal mandrel half (10) projects in relation to the outer half shell (8) at the connected end, and associated with the projecting portion (10b) is a pressure element (14, 15) via which a pivoting force around a horizontal transverse axis in the sense of relieving the front end of the internal mandrel half (10) can be applied to the internal mandrel half (10).
9. An apparatus according to one of claims 6 to 8,
   characterised in that the supporting members (16) are formed in a comb batten (17).
10. An apparatus according to one of claims 4 or 8,
    characterised in that a vertically adjustable supporting construction (18) for the sheet metal blank (B) to be introduced into the form gaps (9) is provided immediately below and in the receiving position between the form tool halves (2, 3).
11. An apparatus according to claim 10,
    characterised in that the supporting construction (18) has at the entrance of each form gap (9) a deflecting plate (20, 21) extending over the entire length of the form gap (9) and borne resiliently in the direction in which the form tool halves (2, 3) move.
12. An apparatus according to one of claims 4 to 11,
    characterised in that associated with one of the two form tool halves (2, 3), more particularly the fixed one, is a retractable stop (25) at the top for the longitudinal edge of the portion of the sheet metal blank (B) shaped in said form tool half (2).
13. An apparatus according to claim 12,
    characterised in that the stop (25) has a tip (26) so asymmetrically constructed that when the other longitudinal edge impinges on said stop (25) the stop yields, releasing one longitudinal edge, and both longitudinal edges impinge on one another.
14. An apparatus according to one of claims 4 to 13, and more particularly for the performance of the process according to claim 2,
    characterised in that a tool (27) acting on the longitudinal edges in the sense of moving them together is associated with the top zone.
15. An apparatus according to one of claims 4 or 14,
    characterised in that the form gaps terminate at the top in a common horizontal plane.
16. An apparatus according to one of claims 4 or 15,
    characterised in that an intercepting bowl (30) for waste materials occurring during welding is disposed in the zone of the top of the internal mandrel halves (10).
17. An apparatus according to claim 16,
    characterised in that the intercepting bowl (30) is disposed fixed and extends over the entire length of the form tool halves (2, 3).
18. An apparatus according to claim 17,
    characterised in that the intercepting shell (30) is connected tightly to the internal form halves (10) and cooperates with the exposed longitudinal edge zones of the tube formed from the sheet metal blank (B) to form a channel.
19. An apparatus according to claims 17 or 18,
    characterised in that the intercepting bowl (30) is made of a flexible material and has a V-shaped cross-section.
20. An apparatus according to claim 16,
    characterised in that the intercepting bowl (30) is constructed to move together with the welding device (5).
21. An apparatus according to claim 20,
    characterised in that the intercepting bowl (30) is borne at the end face by a tappet for the ejection of the internal mandrel halves (10).

Images