EP3302841B1 - Method for producing open-seam pipes from sheet metal panels - Google Patents

Description

The invention relates to a method for producing slotted tubes from sheet metal plates, in particular thick metal sheets, wherein provided on their longitudinal sides with bevelled metal sheet a tube forming press, in which it rests on one of two horizontally spaced support bodies existing lower tool from a raised and lowered Upper tool is formed by applying a bending force progressively to the laterally seam welding with a gap opposite, longitudinal side bending edge having slot tube. Such a method is known from z. B. WO 2009/023973 A1 , One of the most widely used methods for producing sheet metal tubes is the tube molding process with progressive molding or bending steps on tube molding presses. A pipe forming or tube bending press has usually in a base frame one of two laterally spaced juxtaposed support or bending bodies existing lower tool and a vertically engageable from above against the lower die, carried by a raisable and lowerable bending bar, over the entire length the metal sheet extending upper tool with which a bending force can be applied to the resting on the lower die metal sheet.
For the production of a pipe or large pipe according to the progressive molding process several successive steps are required. The metal sheet is pre-bent at the longitudinal edges in a first step, usually in a separate edge banding press. The pre-bending of the longitudinal edges is carried out so that the tube radius in the deformation of the slot tube in the region of the later seam, where the longitudinal edges of the bent to the tube sheet metal plates are opposed to Längsnahtschweißung with a gap uniformly formed. The thus pre-bent metal sheet is then inserted into the pipe molding press and there the subjected to actual bending process. In this case, a bending force is applied to the metal sheet by depressing the press upper part, which sets under the action of the bending load value and carried by this, upper mold a deformation of the metal sheet. This procedure is repeated several times until the metal sheet has been converted to the slot pipe.

By the DE 42 15 807 C2 is a running in frame construction Rohrbiege- or tube molding press has become known. The trained as a bending tool sword is guided vertically in side uprights of the frame. This upper bending tool is attached to piston-cylinder units to a small extent gimbal movable and rests on this against the upper frame cross member. The support bodies of the lower bending tool are carried by a table which also supports piston-cylinder units coaxial with the upper piston-cylinder units. The counteracting piston-cylinder units are to prevent bending of the table, even if the lower frame crossbar should bend under the working load of the press. For this purpose, individual piston-cylinder units are subjected to more or less pressure.

In particular, in the molding of thick-walled tubes with a small diameter on tube forming presses according to the so-called JCO method, starting at a longitudinal or bending edge of the metal sheet a first semicircular shape, the "J" bent and then the thus pre-bent metal sheet from a manipulator is shifted so far that starting with the other longitudinal or Anbiegekante the metal sheets to a "C", resulting in the second semicircular shape, and ultimately is formed into an "O", has a horizontally necessary large distance between the juxtaposed supporting or bending bodies of the lower tool proved to be problematic.

At the beginning of the bending process with successive bending steps, the metal sheet rests flat on one of the support or bending bodies, while a longitudinal or bending edge rests only with slight overlap on the other support or bending body, so that in the application of the bending force by the bending load this longitudinal or bending edge of the support or bending body can slip and thus the bending process must be canceled.

The invention is therefore an object of the invention to provide a method of the type mentioned without the disadvantages described, so that the metal sheet from the beginning without problems progressively transform or can be molded.

This object is achieved according to the invention in that at least the bending sections following the bending edges of the metal sheets immediately adjacent from the outside in each case are deviated differently from a numerically ascending bending step sequence in the pilgrim step method. In this procedure for forming or molding of the metal sheet is not started at the first following the bending edge bending section, but the first bending step takes place in the second bending section. Then, the first, then the fourth, and then the third bending section and so on are formed. Thus, it is advantageously achieved that at the beginning of the bending process not only the bending edge, but beyond at least a partial length or width of the first bending portion rests on a support body of the lower tool, while horizontally opposite the metal sheet is supported unchanged by the other support body. Thus, depending on the bending step width, a nearly symmetrical support of the metal sheet in the effective region of the upper tool on the supporting bodies of the lower tool can be achieved via the bending sections adjacent to the upper tool on both sides. A slipping or pushing away the now with sufficient overlap, namely the bending edge and the first bending section, resting on the support body metal sheet at the beginning of the forming or Einformvorgangs is thus effectively prevented. As a further advantage, it is possible to realize a greater tool spacing and thus correspondingly lower forming forces.

After a first semicircular shape of the metal sheet has been produced in accordance with the procedure described above, the metal sheet is moved so far on the support bodies that starting with the second bending step at the other, opposite bending edge according to the above-explained pilgrim method, the second semicircular shape of the metal sheet is bent.

A preferred measure according to the invention provides that for carrying out the second bending step following the second bending step in the second bending section for forming the first bending section, the metal sheet is laterally withdrawn and prepositioned at a steep angle between the lower tools with support of the bending edge on one of the support bodies. The fact that the metal sheet is pre-bent by the leading first bending step away from the longitudinal or bending edges in the second bending section, a relatively steep employment of the metal sheet between the support bodies can be achieved, so that for the subsequent first bending step, the bending edge with sufficiently large overlap rests on a support body and can not slip off.

An advantageous proposal of the invention provides that at least in relation to the immersed from the longitudinal axis of the progressively formed metal sheet upper tool predetermined once left-sided and once right-hand bending step is made with respect to the other bending steps lower indentation, and that finally by applying a From the outside on this non-circular preform in each case targeted in the previously on both sides of the middle of small molded areas impacting Zudrückkraft the finished slot tube is formed. By thus deliberately an initially tailored non-circular preform with partially lower indentation, z. B. is generated with a bend of 12 ° instead of a bend of 24 °, can form a largely circular slot tube geometry with minimal slot.

Furthermore, it is achieved by partially lower indentation or reduction of the press-in depth that during the molding of the metal sheet into a slot pipe by the pilgrim step method according to the invention in each case during the last bending steps to produce the first and the second semicircular shape, the bending edges do not interfere with the lifting and collapsible upper tool or bending bar collide.

Figur 1

in schematischer Weise den Beginn der Einformung einer Blechtafel gemäß dem Stand der Technik auf einer Rohrformpresse, ausgehend von oben nach unten mit der vorpositionierten Blechtafel (a), der Aufbringung der Biegekraft durch ein Biegeschwert (b) und dem nach der Krafteinwirkung sich abhebendem Biegeschwert (c);

Figur 2

in schematischer Weise den Beginn der Einformung einer Blechtafel nach dem Pilgerschritt-Verfahren, startend mit dem zweiten Biegeabschnitt auf einer Rohrformpresse, ausgehend von oben nach unten mit der vorpositionierten Blechtafel (a), der Aufbringung der Biegekraft durch das Biegeschwert (b) und dem nach der Krafteinwirkung sich abhebendem Biegeschwert (c);

Figur 3

in schematischer Weise die weitergehende Einformung der Blechtafel mit dem nunmehr auf den ersten Biegeschritt folgenden, im ersten Biegeabschnitt nachgeschalteten zweiten Biegeschritt auf der Rohrformpresse, ausgehend von oben nach unten mit der in einem steilen Winkel vorpositionierten Blechtafel (a), der Aufbringung der Biegekraft durch das Biegeschwert (b) und dem nach der Krafteinwirkung abgehobenen Biegeschwert (c);

Figur 4

ein die Biegeschritte bzw. Biegeabschnitte nach dem Pilgerschritt-Verfahren aufzeigendes, schematisch dargestelltes Schlitzrohr; und

Figur 5A, 5B

eine Nach- bzw. Umformung einer unrunden Vorform in mindestens zwei Zudrück- bzw. Biegeschritten, und zwar in einem ersten Biegeschritt durch Kraftbeaufschlagung der unrunden Vorform links neben dem Schlitz bzw. Spalt (Figur 5A) und nach Drehung der unrunden Vorform in einem zweiten Biegeschritt durch Kraftbeaufschlagung rechts neben dem Schlitz bzw. Spalt (Figur 5B),.

Further features and details of the invention will become apparent from the claims and the following description of an embodiment of the invention shown in the drawings. Show it:

FIG. 1

schematically the beginning of the molding of a metal sheet according to the prior art on a pipe-forming press, starting from top to bottom with the prepositioned metal sheet (a), the application of the bending force by a bending load (b) and the bending rate after the force acting ( c);

FIG. 2

schematically the beginning of the molding of a metal sheet according to the pilgrim method, starting with the second bending section on a tube forming press, starting from top to bottom with the prepositioned metal sheet (a), the application of the bending force by the bending rate (b) and after the force acting on the bending load value (c);

FIG. 3

schematically the further molding of the metal sheet with the now following the first bending step, in the first bending section downstream second bending step on the tube press, starting from top to bottom with the pre-positioned at a steep angle metal sheet (a), the Application of the bending force by the bending rate (b) and the bending rate (c) lifted after the application of force;

FIG. 4

a slit tube schematically showing the bending steps or bending sections according to the pilgrim step method; and

Figure 5A, 5B

a reshaping or deformation of a non-circular preform in at least two Zudrück- or bending steps, in a first bending step by applying force to the non-round preform to the left of the slot or gap ( FIG. 5A ) and after rotation of the non-round preform in a second bending step by applying force to the right of the slot or gap ( FIG. 5B ) ,.

On as such a well-known tube forming press 1 is after FIG. 1 one on their long sides with Anbiegekanten 2, 3 provided sheet metal plate 4 to a finished slotted pipe or reshaped. To support the metal sheet 4 during the forming process, a two horizontally spaced support body 6a, 6b-pointing lower tool 7 is provided, wherein the forming force is applied by a raisable and lowerable bending rate 8. At the beginning of the forming process, the metal sheet 4 is positioned with respect to the bending rate 8 so that in the first forming or bending step, the forming force exerted by the bending rate 8 acts on the first bending section 101 following the bending edge 3, the bending edge 3 acting against the bending edge Support body 6b is pressed. By only a small contact surface of the bending edge 3 on the support body 6b, the bending edge 3 and the metal sheet 4 from the support body 6b in the space 9 between the support bodies 6a and 6b slip, as in Figure 1c clarifies, whereupon the forming process must be canceled.

The transformation of a metal sheet 3 to a slit pipe 5 according to the Figures 2 and 3 is performed in the pilgrim step method. Referring to the in Fig. 4 Accordingly, the first forming or bending step in the second bending section 102 following the bending edge 3 is performed according to exemplary bending sections 101 to 106 and 107 to 112 and 113 of the slot tube 5. The bending edge 3 is thereby supplemented by the width of the first bending section 101 with a sufficiently large support surface pressed against the support body 6b and thus can not slip during the forming process.

For subsequent bending step, the metal sheet is moved laterally from an example manipulator to the left and pre-positioned at a steep angle between the support bodies 6a, 6b due to the already deformed or pre-bent second bending portion 102 sufficient contact surface of the bending edge 3 on the support body 6b. In the now second forming or bending step, the bending force exerted by means of the bending rate value 8 acts on the first bending section 101 following the bending edge 3 (cf. Fig. 3 and 4 ).

The following forming or bending steps can continue to proceed in the pilgrim step method, in which case the subsequent bending steps corresponding to the order of the bending sections 104, 103, 106, 105 for the first and right semicircle 10 of the slot tube 5 (see Fig. 4 ).

For forming the second or left semicircle 11 of the slot tube 5, the metal sheet 4 is positioned with the bending edge 2 on the support body 6a, in which case the bending steps in the pilgrim step method analogous to the above-described deformation of the first semicircle 10 in the order of the bending sections 108, 107th , 110, 109, 112, 111, 113 (cf. Fig. 4 ).

In, for example, the bending sections 105 and 111, a smaller bending of the metal sheet 4 can be selectively carried out than in the other bending sections become. There are thus defined two regions 12a, 12b corresponding to the respective bending step, as in FIGS Figures 5A and 5B represented, so that a non-round, yet prefabricated for preforming preform 13 is achieved.

As in the Figures 5A and 5B is shown, the Zudrückkraft for producing the finished, largely circular slot tube 5 is applied from the outside to the non-circular preform 13 on the bending bar 8.

The non-circular preform 13 is positioned so that the less molded portion 12a located to the left of the slit 14 is at a nine o'clock position as in FIG FIG. 5A shown.

The processes of this first Zudrück bending step are in FIG. 5A illustrated, starting from left to right with the positioned non-circular preform 13, the application of the compression force by the bending rate 8 and the lifted after the application of force bending rate. 8

The second press bending step is - in the same sequence as before - in FIG. 5B illustrated. In order to optimize the bending moment, the preform 13, which is still non-circular in its right-hand semicircle 10, has been positioned such that the area 12b, which is formed less to the right of the slot or gap 14, occupies a three o'clock position. The applied by the bending load 8 now on this side of the preform 13 Zudrückkraft F (middle figure) brings the non-circular preform 13 in the final, largely circular shape of the finished slot tube 5 with a thereby achieved small slot or gap 14 (Fig. Fig. 5B Right figure on the outside).

LIST OF REFERENCE NUMBERS

1

Pipe forming press

2

Anbiegekante

3

Anbiegekante

4

metal sheet

5

slotted tube

6a, b

support body

7

lower tool

8th

bending rail

9

free space

10

right semicircle

11

left semicircle

12a, b

less molded areas

13

out of round shape

14

Slot / gap

101

bending section

102

bending section

103

bending section

104

bending section

105

bending section

106

bending section

107

bending section

108

bending section

109

bending section

110

bending section

111

bending section

112

bending section

113

bending section

Claims (3)

1. Method of producing slotted tubes (5) from sheet-metal panels (4), particularly thick sheet-metal panels, wherein a sheet-metal panel (4) provided at the longitudinal sides thereof with bent-up edges (2, 3) is fed to a tube-forming press (1) in which while resting on a lower tool (7) consisting of two horizontally spaced-apart support bodies (6a, 6b) the panel is formed by a raisable and lowerable upper tool (8), through application of a bending force, continuously into the slotted tube (5) having longitudinal-side bent-up edges (2, 3) which are opposite one another by a gap for later longitudinal seam welding, characterised in that in departure from a numerically rising bending step sequence at least the bending sections (101 to 106 or 107 to 113) which follow the bent-up edges (2, 3) of the sheet-metal panel (4) directly adjacently in each instance from outside to inside are reshaped in the Pilger step method.
2. Method according to claim 1, characterised in that for carrying out the second bending step, which follows the first bending step undertaken in the second bending section (102 or 108), for reshaping the first bending sections (101 or 107) the sheet-metal panel (4) is drawn back laterally and pre-positioned at a steep angle between the lower tools (6a, 6b) with support of the bent-up edge (2, 3) on one of the support bodies (6a, 6b).
3. Method according to claim 1 or 2, characterised in that a forming process which is smaller by comparison with the other bending steps is undertaken at least in a bending step once to the left and once to the right referred to the centre predetermined by the longitudinal axis of the centre predetermined by the longitudinal axis of the upper tool (8) plunging into the continuously formed sheet-metal panel (4) and that finally the finished slotted tube (5) is formed through application of a pressurable closing force (F) acting from outside on this non-circular preliminary shape (13) in each instance selectively in the regions (12a, 12b) previously shaped to lesser extent on either side of the centre.

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