DE3940984A1 - Forming of sheet metal shells or tubes - by using pair of bending rollers with mechanism to swing one roller about the axis - Google Patents

Abstract

The sheet metal is formed into a circular sheel or tube, by bending the sheet by means of rollers. The sheet metal is guided by passing it between the gap between two sets of rollers (3,4) with the one set (4) mounted above the other set (3). After passing between these sets of rollers (3,4), the sheet metal passes between the pair of bending rollers (1,2). These bending rollers are so mounted that one roller can be swung about the axis of the other roller through an angle (alpha). The magnitude of the angle (alpha) determines the radius of curvature of the shell or tube. USE - Forming sheet metal shells or tubes.

Description

The invention relates to a method for bending sheet metal parts Shells or pipes, especially of partially open or closed shells and tubes, thin sheets over columnar Guides the nip of a bending machine with bending rollers in the Continuous processes are fed.

This method is in connection with a device of the type three roll bending machines, including four rolls of the known Roll bending machines can be provided, already known. These Machines serve the purpose, starting from a sheet metal, half-open or closed round profiles, in particular pipes or shells to bend. These machines, especially in the field of four Roll bending machines, one bending roll in front of the nip and one further bending roller or guide roller is connected downstream of the nip and fixed guide rollers are arranged in a pressing area, can also be controlled by CNC and otherwise already Bend asymmetrical shapes.

In the known method and the device with roll bending are essentially in the vertical direction the the nip or downstream bending rollers shifted, resulting in the desired Way the deformation of the inserted sheet to a round profile is achieved. In the known method with the three or four Roll bending rolls, it is disadvantageous that one does not rotationally symmetrical profiles, d. H. for profiles the positive and  have negative bend radii, one behind the other subsequent bending, with material being drawn from a spool, not is made possible.

If you want positive and subsequent in the known bending machines different, e.g. B. negative, bend radii, so it must sheet to be deformed are either re-introduced - in particular for short sheets - or a second bending machine must be in Arrangement can be connected in series.

Another disadvantage of the known bending machine could be considered be drawn that considerable sheet losses can arise. At at known 4 roller bending arrangements can be almost Bend without loss, but it remains a short distance at least in the beginning not yet bent sheet metal part left, which in the further Continuous process, although the previous sub-arrangements already are rounded, must be re-bent.  

Incidentally, in known roll bending machines, in particular with three Roles, considerable work required. When a sheet is rounded In this way, one side of the sheet must first be inserted and at the first rounding of the sheet should be more precise after a Pass through the machine without further rounding out of the machine be removed and when adjusting the bending rollers in reverse Direction to be reintroduced into the machine, eventually at high rounding accuracy in connection with a trouble-free concentricity the machine itself has an almost circular cross-sectional profile to reach. Should be in a known three roller bending machines low workload must be created, so only a partial Round bending of a sheet metal part can be accepted, whereby in Infeed area may be the not yet finished bent Profile must be removed by an oxyfuel cut.

For the rest, the forming capacity is also known Roll bending machines can be improved because they are relatively large Delivery routes result and the machine costs are higher because three or four driven rollers are used, which in the Inlet area pressed up and possibly in the outlet area different pressing force be pressed.

It is therefore in the known in particular four roll bending machines provided that especially in the inlet area in connection with a vertical lifting under pressure of an infeed roller the sheet in particular is inserted obliquely into the subsequent nip, but there are also disadvantages, particularly in the case of long ones large-volume sheets in connection with the oblique insertion Waviness can result, even in the guide gap itself undulated distortion may exist.

The object of the present invention is therefore a bending arrangement with three or four bending rollers especially in connection with Bend arrangements of the type mentioned in such a way that at high efficiency with practically no sheet loss in at least two different positive and consecutive bending directions negative bending radii can be bent with very high rounding accuracy can and still achieved a high throughput speed can be.

To solve the problem, the method provides that starting from a straight line guidance of the sheet to be deformed the deformation of the sheet itself by pivoting at least one which introduces two bending rolls.

In the device according to the invention it is provided that two Bending rollers depending on the sheet and profile profile or profile thickness at a distance and in the adjustment angle to form a non-positive and positive Closing under pressure to be delivered to each other, at least one bending roller can be pivoted around the center of the other bending roller and here the sheet to be deformed in the roll gap via inlet and Guide rollers and / or is fed via gap-shaped centering.

The essence of the invention with the centro-geometric roll bending (ZGRB process called) is therefore also in that in the nip a form-fitting almost close to a force-fitting Friction can be produced, this geometric design of the Arrangement of the bending rollers in their kinematics for both sheet metal and can be used for profiles.

Accordingly, at least one bending roller uses the center point in its Swiveling and is therefore moved centrally. In this way lies  e.g. B. the lower roll with its center on a circle whose Center the center of the other z. B. is the top roll. There are thus providing two roles, one from the center of a role starting a circle around the axis of rotation of the other role and vice versa. The two roles will alternate in this way pivoted, once in a positive and negative direction, so accordingly negative and positive bending radii are generated and vice versa.

Based on this kinematics, it follows that the two Rollers are connected to each other via a yoke, being more advantageous Training this yoke is adjustable in length so that the both bending rollers or rollers can be fed to each other hereby set a nip between the rollers.

Another essential feature of the invention is that, in contrast to the prior art the technology where the sheet metal slants over the infeed surface is introduced into the nip in the manner of an entry angle, at the invention fed the sheet metal via a straight guide to the nip becomes. This guide can be designed with roles; but it can wedges, runners or the like can also be used, in particular this arrangement can be brought directly to the nip, which allows bending without loss of sheet metal. The difference is therefore essentially in that in the prior art Inclination of the inlet surface is provided, while at the Invention of the sheet in a straight line without deformation horizontal guides are fed to the nip.

The sheet metal parts are therefore fed into the bending rollers via Inlet surfaces, especially on sliding blocks or rollers, which at the invention can be arranged above and below, whereby a Fixed point is created and as soon as one of the two bending rollers around the center  is moved, a contact surface is created to the sheet metal, where the plane of the sheet is changed, whereby with considerable precision - because it starts from zero - the sheet is bent. It works essentially because a lever in connection with a Lever arm the bending rollers are pivoted, resulting in a high Precision results in connection with turning from a zero point out. In the following, the essential features of the invention in Bending a mirror-symmetrical open profile explained:

In the invention it is essential that in the inlet area Counter moment is present which is caused by sliding jaws; Shoes or rolls is produced. In the outlet area there is a mirror image adjustment the sliding jaws, shoes or rollers arranged there. The Bending area therefore extends essentially from the Inlet surface and the zero point there over at least one swiveling bending roller, which enables z. B. in a positive direction upwards or when swiveling the upper one Bending roll can be bent in the negative bending direction. In The bending rollers themselves can also be connected to it especially vertical or angular distance from each other in particular be moved outwards in order to close a nip in this way create, which can also be designed so that in connection with profiled bending rollers desirable any profiled sheet metal parts can be bent in the radius. When entering the sliding jaws, shoes or rollers arranged on the inlet side first not adjusted while the sliding jaws arranged on the outlet side, etc. are extended and are not in contact with the workpiece. As soon as half of the processing of the workpiece (with mirror symmetry shaped workpiece) is reached, the outlet side are arranged Sliding jaws etc. retracted and arranged on the inlet side Sliding jaws etc. extended (out of engagement with the workpiece brought), so that now a mirror image (opposite)  The lower bending roller can be adjusted. Here there is more options:

• a) the sliding jaws arranged on the outlet side are the Traced workpiece contour. The nip between the bending rollers remains the same, with the lower roller being adjusted to the left. Thereby the desired forming is achieved and that until the end of the sheet, because the forming takes place on the inlet side.
• b) the sliding jaws arranged on the outlet side remain in their original position and the adjustment angle of the lower roller changes accordingly by an equal reshaping of the first half of the mirror-symmetrical plate also with respect to the second half to reach.

In the execution according to a) one has the same adjustment angle of the lower roller to the left and right when the slide jaws contour the Workpiece is adjusted (updated).

The execution according to b) has a different one Adjustment angle of the lower roller to the left compared to the Entry position of the workpiece to the right.

• c) the nip between the opposing rollers changed, the control programs according to a) or b) are then carried out. As a result, the bending radius of the workpiece can also be increased to be changed.

Analogously, open, asymmetrical or closed can also be used Profile shapes are bent.

In the description above, the bend was a positive one Bending radius described (the sheet is bent upwards). In analogous to the above description, the upper bending roller  can be adjusted to negative bending radii (directed downwards) produce.

By alternately adjusting the upper and lower bending rollers in the For the purposes of the above description, the continuous process can consecutive positive and negative bend radii to each other be added.

In the following the invention is based on practical embodiments explained in connection with the drawings. In connection with the the following description further features according to the invention in Highlighted connection with advantages of the invention.

The subject matter of the present invention can also in the Combination of the individual claims used with each other will.  

Show it:

Fig. 1a shows a known four roller bending arrangement according to the prior art;

Fig. 1 of the invention Zentro geometric roll bending method with a bending roller arrangement with upstream guiding or pressing rollers that;

FIG. 2 shows a bending roller arrangement according to FIG. 1 with the direction of insertion reversed;

Figure 3 shows a profile after passing through the bending rollers with negative and positive bending radii in connection with a round profile arrangement.

Figure 4 shows the bending assembly according to the invention with illustration of the profile in two different directions, in particular in a vertical plane during processing the material to be profiled from a coil.

Figure 5 shows a possible according to the invention profiling with negative and positive bending radii.

Fig. 6 is a representation of a bending assembly with lead-in area with inlet wedges or -kufen;

Fig. 7 shows the bending arrangement according to the invention, showing the bending rollers in a jointly pivotable yoke.

According to Fig. 1a it can be seen that a roller A movable in an upward pressing movement is provided in the region of the insertion of the sheet metal part to be deformed, as a result of which an inclined insertion direction is formed and the sheet metal part subsequently passes through the nip. Only fixed press rolls C, D act in the roll nip itself, and in the area of the outlet a retractable guide roller B additionally guides the tapered profile.

In the prior art in the arrangement according to FIG. 1 a described above, a bend in connection with an inclined position of the sheet to be inserted is accordingly carried out on an entry surface, which represents an entry angle of the sheet at the nip. In contrast, the method according to the invention according to FIG. 1 and the following figures, including FIG. 7, is present in connection with a rectilinear insertion surface, the roll nip also being rectilinear, and when the run-in area of the roll nip is reached, both bending rollers are pivoted.

In the invention, it is provided that at least one of the bending rollers is arranged pivotably, specifically according to FIG. 1, where bending is carried out around a center, the center lying in the axis of rotation of another bending roller.

In the drawing in Fig. 1, a preferred bending roller arrangement of a bending machine according to the invention is shown, which is to be placed under protection.

Here, several modifications are possible, which will result from the following Describe description.

In the configuration shown in FIG. 1, two bending rollers 1 , 2 are arranged approximately vertically to one another in a position from which the pivoting movement originates, the bending rollers 1 , 2 defining a roller gap 2 a between them. In the basic position, from which the pivoting movement can also proceed, these bending rollers 1 , 2 thus lie one above the other in a vertical 18 .

On the inlet side, so-called inlet rollers 3 , 4 are arranged in front of the bending rollers 1 , 2 , which are also arranged approximately vertically one above the other.

These feed rollers 3 , 4 , which are also referred to in FIG. 2 guide rollers 33 , 34 , are preferably driven, but need not necessarily be driven. They are adjustable in the arrow directions 7 , 8 according to FIG. 1. The adjustment in the arrow directions 7 , 8 is carried out for the purpose that different sheet thicknesses can be processed and that the roller gap, which is formed between the inlet rollers 3 , 4 , 33 , 34 , is always in the same plane as the roller gap 2 a, which lies at the same level for the bending rollers 1 , 2 at least in the basic position.

It is important that if you only bend in one direction, for example if the sheet 5 runs in in the direction of arrow 6 and you only want to bend in the positive direction, then the upper feed roller 4 can possibly be omitted.

Conversely, this applies similarly, if, in the case of a similar configuration, bending is only negative, then the lower feed roller 3 could be pivoted away.

It is now important that the bending rollers 1 , 2 are driven in rotation.

The axes of rotation 19 , 20 each lie on an adjusting circle 16 and 17, respectively.

That is, the axis of rotation 20 of the lower bending roller 2 lies on an adjusting circle 17 , which adjusting circle has the axis of rotation 19 of the upper bending roller 1 as the center.

Conversely, the upper bending roller 1 lies on an adjusting circle 16 , the center of which is formed by the axis of rotation 20 of the lower bending roller 2 .

It follows from this that the respective bending roller 1 or 2, the positions 1 'and 2 ' can be pivoted, for example, an adjustment angle 13 or 14 being defined here.

It is also important that the axes of rotation 19 , 20 and thus the bending rollers 1 , 2 in the arrow directions 9 , 10 are adjustable in the vertical direction. As a result, the nip 2 a between the bending rollers 1 , 2 is adjusted according to the respective sheet thickness. The sheet metal 5 is drawn in in the direction of the arrow 6 by the frictional force, in connection with a pressing in the nip 2 a between the bending rollers 1 , 2 . At the moment when the bending roller 1 , 2 is adjusted by the adjustment angle 13 or 14 , the sheet is bent up or down from the horizontal plane, with a positive or negative bending radius being applied. It is important that this bending radius is applied with almost no loss or that it is bent with high efficiency. The losses result from the material thickness.

The radius dimension of the curved profile can now be adjusted within wide limits, namely as a minimum radius, a radius that corresponds to the radius of the bending roller 1 , 2 and this radius can now be opened continuously, ie converted into larger bending radii, depending on how one z . B. in the lower bending roller 2, the adjustment angle 14 is adjusted during the bending process, with the axis of rotation 20 being approximately vertically adjusted in the arrow directions 10 at the same time.

This means that every infinite adjustment of the bending radius of the curved Sheet possible.

It was just turning z. B. mentioned in the positive bending direction by adjusting the lower bending roller 2 .

In an analogous manner, a negative bending radius can of course also be infinitely adjusted by correspondingly adjusting the angle αI corresponding to the angle 13 of the upper bending roller 1 .

With this adjustment option, it is now possible with little effort Movement effort not only rotationally symmetrical bending bodies produce, but also so-called clotoids, d. H. Body of them Bending radius were changed over the entire length.

It is now important that you have the smallest or smallest adjustment paths for bending needs such clotoids, so far in the known three or Four roller bending machines require significantly longer adjustment paths were.

It only needs, for example, the lower bending roller 2 in the position 2 'to be adjusted by a small adjustment angle 14 and at the same time the bending roller 2 is adjusted in the arrow direction 18 upwards. This is possible with little effort and adjustment path, this adjustment path being considerably less in comparison to the known three or four roller bending machines.

In this way, profiles of the highest form accuracy can be bent, because in practical execution in infinitesimally small steps seen the length of the sheet, always different curves Rounding radii can be added to each other.

Because you have relatively little adjustment - as above described - can already achieve such precise curves, follows from this that you can now work at high throughput speeds can, because the adjustment paths are so short in this way. With that the Production management of such a bending machine compared to the previously known bending machines multiplied. So it's not just that Accuracy of the bending process increases, but also that Process speed in relation to the turning process in connection with the run.

Accordingly, the sheet is held at least on the inlet side of inlet rollers 3 , 4 or runners such that behind the inlet rollers 3 , 4 or rollers 33 , 34 at least two bending rollers 1 , 2 lying approximately one above the other are arranged vertically one above the other in a possible basic position, and such that the axes of rotation 19 , 20 of these bending rollers 1 , 2 are connected to one another, so that the respective bending roller 1 , 2 can be adjusted by a circle that passes through the axis of rotation of the other bending roller in the adjustment angle αI and / or αII.

It is also important that the machine configuration, as described in Fig. 1, not only allows a bending process in the direction of arrow 6 , but also in the opposite direction in the direction of arrow 6 '.

First, however, a bending process with a machine according to FIG. 1 will be explained in more detail with reference to FIG. 3.

There is a profile 23 , which is now with the starting position 24 initially in the nip 2 a between the bending rollers 1 , 2 - z. B. according to FIGS. 1, 2 and 4 - arrives.

The lower bending roller 2 is now adjusted in the adjustment angle 14 , 14 ', with the axis of rotation 20 being adjusted downwards in the direction of the arrow 10 .

This results from the fact that the radius of curvature of the profile 23 is smaller at position 26 than at position 27 . This can only be achieved by moving the axis of rotation 20 downward in the direction of the arrow 10 . As a result, the profile 23 opens during the passage in the direction of arrow 25 , ie the radius of curvature becomes ever larger, as can be seen by comparing the positions 26 and 27 . After passing approximately at position 27 , the adjustment angle 14 is again adjusted clockwise, ie the bending roller 2 returns to the vertical 18 , as a result of which a straight bending section 28 is reached. At position 29 there is no longer a bend.

The bending of the profile section 23 with the machine configuration according to FIG. 1 is thus ended.

Then the inlet rollers 33 , 34 are lifted, ie in the direction of the arrows 7 , 8 from the sheet in the vertical direction.

New feed rollers 33 , 34 are now used, which are shown in FIG. 2. In the following it is given with reference to FIG. 2 how the profile section 30 of this profile is bent according to FIG. 3.

The profile section 23 extends from position 29 to position 24 , while the profile section 30 extends from position 29 to position 35 .

The completely bent profile section 23 now lies at position 29 between the bending rollers 1 , 2 arranged vertically one above the other.

It is important that the upper feed roller 33 is lifted and extended during this bend, so that it no longer lies against the curved profile section 23 and can interfere with this bending process.

The sheet is now further guided in the direction of arrow 6 through the nip between the bending rollers 1, 2, but where now the lower bending roller 2 is moved clockwise about the displacement angle 14 ', and in the case of the profile section 30 shown in Fig. 3, the adjustment angle 14 'Increases continuously.

This means that at position 36 there is a relatively small adjustment of the adjustment angle, while at position 37 the adjustment angle increases until it has a maximum at position 35 .

In this way, a clotoid curve is thus bent in the profile section 30 . Here takes place simultaneously an adjustment of the axis of rotation 20 in the direction of arrow 10 '- of Fig. 2 -, that is, now the axis of rotation 20 in the vertical upward direction is adjusted in reversing to the previous bending process of Figure 1, where the axis of rotation 20 in the direction of arrow 10 after. was adjusted vertically below.

In order to ensure that the profile section 23 is guided while the profile section 30 is being bent, it is important that the lower guide roller 34 follows the profile section 23 , that is to say it rests positively and non-positively, in order to ensure support during the bending process of the profile section 30 .

The same relationships also apply with regard to the infeed roller 3 in the machine configuration according to FIG. 1, which remains in its plane and always rests on the horizontally incoming sheet 5 in a non-positive and positive manner.

It is now possible for the first time to bend a profile according to FIG. 3, with a mirror-image profile being able to be bent without loss in a single work step, that is to say at positions 24 and 35 there are no longer straight ends which have to be subsequently separated, but rather these The ends of positions 24 and 35 are already completely bent, whereby these ratios apply to plate material.

It is now possible, according to FIG. 4, to produce a bending profile 39 with one machine, as shown in FIG. 5.

Here, the sheet material 5 - according to FIG. 4 - is drawn off from a roll 40 , which is arranged to be height-adjustable in the direction of the arrows 41 , in order to always keep the take-off plane in the plane of the nip 2 a between the bending rolls 1 , 2 .

The bending now takes place starting at position 38 by adjusting the bending roller 2 in the adjustment angle 14 counterclockwise, in such a way that the adjustment angle goes from position 38 to position 42 to zero (according to the direction of transport of the sheet (arrow direction 6 ) in Fig. 5).

The profile section 43 would then be completely bent, as is also shown in FIG. 4, for example.

In a similar manner, the adjustment angle 14 of the lower bending roller 2 is further adjusted, as a result of which the position 42 to position 44 are bent.

From position 44 , the lower bending roller 2 is now held and is fixed in the vertical 18 , while the upper bending roller 1 is now adjusted clockwise by the adjustment angle 13 on its adjustment circle - as explained with reference to FIG. 1. Starting from position 44 , it is thus bent with a continuously changing adjustment angle beyond neutral position 45 - according to FIG. 5 - to position 46 .

This profile section between positions 44 and 46 is referred to as profile section 47 .

In Fig. 4 it is entered that the profile section 43 , which is denoted by solid lines above in Fig. 4, then connects as a profile section 43 'to the newly bent profile section 47 .

It is clear that, according to FIG. 5, the now newly bent profile section 47 is in turn followed by a new profile section 48 , which corresponds exactly to the profile section 43 in terms of its manufacture and shape. It can thus be bent to the axis 49 or 18 mirror-symmetrical profile sections 43 , 47 , 48 .

On the outlet side of the bending machine, a cutting shear is arranged in a manner not shown. With these cutting scissors it is now possible to make a cut at positions 38 , 44 , 46 etc., so that exactly identical profile sections 43 , 47 , 48 are obtained.

A particularly simple design of a cutting shear results when the entire bending machine according to FIGS. 1, 2 and 4 works in the vertical direction and not - as shown - in the horizontal direction. This installation position is particularly preferred for thin surfaces in order to avoid an inadmissible deepening of the sheets.

In Fig. 3 it is shown as an embodiment that the thus bent profile sections 23 , 30 can be closed to form a circular tubular profile 50 , specifically at the place of use. This is only one possible exemplary embodiment and the clotoid shape described here was therefore chosen in order to achieve a perfect closure to a tubular profile 50 without deformation of the profile in the case of particularly thin-walled sheet metal.

Fig. 6 shows that the inlet-side feed rollers 3, 4 can also be replaced by sliding blocks 21, 22, as well as the downstream arranged guide rollers 33, 34.

This means that all of the rollers 3 , 4 and 33 , 34 shown here can be replaced by sliding jaws or runners 21 , 22 .

It is also a combination of the inlet-side feed rollers 3, 4 and of the outlet side arranged sliding blocks 21, 22 is possible, and vice versa, that for example the sliding blocks 21, 22 on the inlet side and the guide rollers 33 are arranged at the outlet side 34th

The use of sliding jaws 21 , 22 has the advantage that the guide surface for the profile to be bent can be brought very close to the bending nip between the bending rollers 1 , 2 .

As a result, the contours can be bent more and still with a be bent with greater accuracy.

In an exemplary embodiment, which is only shown schematically in FIG. 7, the principle of the present invention is also shown schematically. It can be seen here that the bending rollers 1 , 2 are connected to one another via a yoke 51 , the axes of rotation 19 , 20 being adjustable with the yoke 51 in the arrow directions 9 , 10 .

Each axis of rotation 19 , 20 is then adjustable to a respective adjustment circle 16 , 17 , the adjustment circle 16 , 17 each having the axis of rotation of the opposite bending roller as the center.

It is important with this principle that the profile is supported on at least one side, that this support is ensured as a counterforce to the bending force arising in the nip between the bending rollers 1 , 2 .

Drawing legend

1 bending roll
1 ′ 2 ′ positions
2 bending rolls
2 a nip
3 infeed roller
4 infeed roller
5 sheet
6 direction of arrow
6 ′ arrow direction
7 arrow direction
8 direction of arrow
9 arrow direction
10 arrow direction
10 ′ direction of arrow
11 Direction of rotation ωI
12 Direction of rotation ωII
13 adjustment angle αI
14 adjustment angle αII
14 ′ adjustment angle
16 adjustment circle
17 adjustment circle
18 verticals
19 axis of rotation
20 axis of rotation
21 sliding jaws
22 sliding jaws
23 profile section
24 start position
25 direction of arrow
26 position
27 position
28 bend section
29 position
30 profile section
33 Leadership role
34 Leadership
35 position
36 position
37 position
38 position
39 bending profile
40 wraps
41 arrow direction
42 position
43 profile section
43 ′ profile section
44 position
45 position
46 position
47 profile section
48 profile section
49 axis
50 tube profile
51 yoke

Claims (7)

1. A method for bending sheet metal parts to shells or tubes, in particular partially open or closed shells or tubes, thin sheets being fed via column-shaped guides to the nip of a bending machine with bending rollers in a continuous process, characterized in that starting from a straight-line guidance of the deforming sheet ( 5 ) the deformation of the sheet ( 5 ) is initiated by pivoting at least one of the two bending rollers ( 1 , 2 ). 2. The method according to claim 1, characterized in that the pivoting radius of the respective bending roller ( 1 , 2 ) from the axis of rotation ( 19 , 20 ) of a bending roller ( 1 , 2 ) is based and thereby runs through the axis of rotation of the other bending roller, wherein also a constant roll gap is formed between the bending rollers ( 1 , 2 ) when pivoting. 3. Process according to claims 1 and 2, characterized in that the sheet to be deformed ( 5 ) is introduced in a straight line into the nip in connection with a pivoting of at least one of the two bending rollers ( 1 , 2 ), depending on the radius of the to be deformed sheet (5) during the passage of the sheet (5), the distance of at least one of the bending rollers (1, 2) is changed in the area of a joint yoke (51) in an approximately vertical direction. 4. Apparatus for bending sheet metal parts, in particular for bending semi-open or closed shells or tubes for carrying out the method, thin sheets being fed to the nip of a bending machine with bending rollers in a continuous process, characterized in that two bending rollers ( 1 , 2 ) depending on Sheet and profile course at a distance and in the adjustment angle ( 13 , 14 ) with the formation of a non-positive and positive closure under pressure, at least one bending roller is pivotable about the center of the other bending roller and thereby the sheet metal ( 5 ) to be deformed the roller gap is fed via inlet and guide rollers ( 3 , 4 , 33 , 34 ) and / or via gap-shaped centering means. 5. The device according to claim 4, characterized in that the centering means are designed as wedges, runners, rollers or sliding blocks ( 21 , 22 ). 6. Device according to claims 1 to 4, characterized in that at least one bending roller (1, 2) from the center of the other bending roller (1, 2), starting placed centrally on a circular arc in motion, and in this case by a common yoke (21 ) is controlled and held. 7. Device according to claims 1 to 4, characterized in that the inlet and guide rollers are arranged closely in front of the bending rollers or the sliding jaws ( 21 , 22 ) in the immediate vicinity of the nip of the bending rollers ( 1 , 2 ).