SWIVEL BENDING MACHINE FOR CREATING AN OPEN HEM ON A SHEET AND SHEET BENDING METHOD

Abstract

A swivel bending machine and method produces a hollow fold on a sheet with a lower beam for supporting the sheet, an upper beam with a wedge-shaped bending edge for clamping the sheet between the upper beam and the lower beam, a rotatable or pivotable bending beam for bending the sheet section of the sheet protruding between the upper beam and the lower beam in a first bending step along the wedge-shaped bending edge into an acute angle, and a movement device for moving the wedge-shaped bending edge out of the sheet section pre-bent into an acute angle. The swivel bending machine further bends the sheet section into a hollow fold in a second bending step with further actuation of the bending beam between the bending beam and the lower beam, while the sheet is fixed against the lower beam by the wedge-shaped bending edge.

Description

FIELD OF THE INVENTION

The present invention relates to a swivel bending machine for producing a hollow fold on a sheet and a sheet bending method relating thereto.

BACKGROUND

Swivel bending machines typically have a lower beam for supporting the sheet, an upper beam-which can be moved vertically between an open and a closed position-and a rotating or swiveling bending beam. A sheet to be bent to a certain angle is first clamped between the upper and lower beam by closing the upper beam, so that the sheet section to be bent protrudes between the upper and lower beam and can then be bent by pivoting the bending beam around a bending edge typically provided on the upper beam.

If hollow folds are produced on a sheet using a swivel bending machine according to conventional methods by vertically “pressing” a sheet section that has already been pre-bent to an acute angle with the upper beam, the problem arises that if the length of the hollow fold is long or the sheet used is thick, the wedge-shaped bending edge including the upper beam will increasingly bend upwards in the middle. The hollow folds produced in this way are therefore less well formed in the middle than in the edge areas and can therefore only be used or produced to a very limited extent or almost not at all.

Furthermore, sheet bending methods and suitable swivel bending machines for this purpose are already known from the prior art, in which the sheet section to be bent on the sheet is first pre-bent into an acute angle in a first bending step by means of the bending beam along a wedge-shaped bending edge and in which the wedge- shaped bending edge is then moved out of the pre-bent sheet section and the hollow fold is subsequently closed in a second bending step by further bending the pre-bent sheet section by means of the bending beam. This is known, for example, from of US 2015/0151346 A1, FR 2 717 109 and U.S. Pat. No. 2,336,105, with U.S. Pat. No. 3,622,584 and CH 392 434 showing further similar bending machines and bending processes.

In the prior art, according to all the above-mentioned publications, the wedge-shaped bending edge is not used in the second bending step (“further bending to close the hollow fold”) and additional means are required to fix the sheet in the second bending step.

Against this background, it is the task of the present invention to provide an improved swivel bending machine and an improved method for producing hollow folds on a sheet with the simplest possible design, with which hollow folds can be produced with great length and high precision.

SUMMARY

This task is solved by the objects with the features according to the independent claims. Advantageous embodiments are the subject of the dependent claims, the description and the figures.

In a first embodiment of the invention, there is thus provided a swivel bending machine for producing a hollow fold on a sheet, which comprises the following components:

• • a lower beam for supporting the sheet,
  • an upper beam with a wedge-shaped bending edge for clamping the sheet between the upper and lower beam,
  • a rotatable or pivotable bending beam for bending the sheet section of the sheet protruding between the upper beam and the lower beam in a first bending step along the wedge-shaped bending edge to an acute angle, and
  • a movement device for moving the wedge-shaped bending edge out of the sheet section pre-bent to an acute angle.

In accordance with this disclosure, it is further provided that the swivel bending machine is set up to further bend the sheet section pre-bent into an acute angle into a hollow fold in a second bending step with further actuation of the bending beam between the bending beam and the lower beam, while the sheet is fixed against the lower beam by the wedge-shaped bending edge.

By forming the hollow fold using the rotating bending beam while simultaneously fixing the sheet against the lower beam using the wedge-shaped bending edge, a hollow fold can be produced over the entire length of the sheet with a particularly high level of precision.

It has been shown that the fixing of the sheet by means of the bending edge during the second bending step, as provided for in this disclosure, permits the production of high-precision hollow folds. It is particularly advantageous that the sheet can be fixed against the lower beam over its entire length by means of the bending edge (after its removal from the pre-bent section), namely in the immediate vicinity of the bending process taking place in the second bending step.

To fix the sheet against the lower beam in the second bending step, the wedge-shaped bending edge can be pressed against the upper side of the sheet with its underside flat or with line contact, depending on the specific design of the movement device specifying the possible positions of the wedge-shaped bending edge.

As already mentioned, a swivel bending machine according to the disclosure comprises a wedge-shaped bending edge-serving as an upper beam tool-for bending the sheet section into the acute angle in the first bending step. Depending on the technical and physical conditions, the angle may not be less than approx. 20°.

The swivel bending machine also comprises a movement device for moving the wedge-shaped bending edge out of the pre-bent section of the sheet so that the sheet section pre-bent to an acute angle can then be bent further immediately without having to move the sheet. This allows sheet parts to be produced quickly and easily.

In a technically advantageous embodiment of the swivel bending machine, the movement device comprises a displacement device for linear pulling out of the wedge-shaped bending edge. This achieves the technical advantage, for example, that the wedge-shaped bending edge can be brought quickly and easily into a position in which the pre-bent sheet section can be bent further without hindrance and at the same time the sheet can be fixed against the lower beam by means of the bending edge. During the linear pulling out (extraction) of the wedge-shaped bending edge, an opening movement of the upper beam can also take place and, after completion of the pulling out (extraction) movement, a renewed closing movement of the upper beam in order to facilitate the repositioning of the wedge-shaped bending edge for the second bending step and to facilitate good fixing of the sheet against the lower beam in the second bending step.

In a further technically advantageous embodiment of the swivel bending machine, the movement device comprises a rotating device for turning out or swiveling out the wedge-shaped bending edge. Here too, in combination with a simultaneous opening and subsequent closing movement of the upper beam, the bending edge can be repositioned quickly for the second bending step, so that the sheet section pre-bent in the first bending step can be bent further without hindrance and at the same time can be fixed against the lower beam by means of the bending edge.

In a further technically advantageous embodiment of the invention, the rotating device comprises a plurality of bending edges. This achieves, for example, the technical advantage that bending edges with different profile shapes can be used on a swivel bending machine, with which sheets can be bent at different angles and shapes.

In another technically advantageous embodiment of the swivel bending machine, the bending beam comprises a bending bar for bending the sheet section. This allows hollow folds to be produced with an even smaller tolerance.

In a further technically advantageous embodiment of the swivel bending machine, the bending bar or the bending beam comprises a crowning for uniformly producing the hollow fold, whereby hollow folds can be produced with even greater accuracy over the entire length of the sheet.

In a further technically advantageous embodiment of the swivel bending machine, the bending bar has a profile which is vertically crowned in the longitudinal direction of the machine, which can also contribute to increased precision in the production of hollow folds.

According to another embodiment, the present invention also relates to a sheet bending method for producing a hollow fold (125) on a sheet (103) using a swivel bending machine, comprising the following steps:

• • (A) Placing a sheet with a sheet section which is initially to be pre-bent to an acute angle on a lower beam of the swivel bending machine,
  • (B) clamping the sheet between an upper beam having a wedge-shaped bending edge and the lower beam,
  • (C) bending of a sheet section protruding between the upper beam and the lower beam by means of the bending beam in a first bending step along the wedge-shaped bending edge to an acute angle,
  • (D) moving the wedge-shaped bending edge out of the sheet section pre-bent to an acute angle and
  • (E) further bending of the sheet section in a second bending step into a hollow fold by further swiveling of the bending beam, while the sheet is fixed against the lower beam by means of the wedge-shaped bending edge.

The method achieves the same technical advantages as the swivel bending machine according to the first aspect, so that reference may be made to the above explanations of the swivel bending machine in order to avoid repetition. Advantageous embodiments of the swivel bending machine already described are of course equally applicable to the sheet bending process.

In a preferred embodiment of the sheet bending process, the wedge-shaped bending edge can be moved out of the pre-bent sheet section in the opposite wedge direction by a movement device.

In a further technically advantageous embodiment of the sheet bending process, the wedge-shaped bending edge is pivoted out or pulled out of the pre-bent sheet section, which may be superimposed by a simultaneous opening and subsequent closing movement of the upper beam. This allows the bending edge to be removed from the pre- bent sheet section with little design effort and repositioned appropriately for the second bending step.

In a further technically advantageous embodiment of the sheet bending process, deflection of the bending beam and/or the bending bar during pre-bending (“first bending step”) or further bending (“second bending step”) is compensated for by crowning. This achieves the technical advantage, for example, that the hollow fold can be produced with even greater accuracy over the entire length.

BRIEF DESCRIPTION OF THE DRAWING

Examples of embodiments of the invention are shown in the drawings and are described in more detail below. They show:

FIG. 1 a front view of a swivel bending machine,

FIG. 2 a cross-sectional view of the swivel bending machine,

FIG. 3 a further cross-sectional view of the swivel bending machine with the bending edge moved back,

FIG. 4 a further cross-sectional view through the swivel bending machine with the bending edge moved back and the bending beam folded up,

FIG. 5 a further cross-sectional view of the swivel bending machine with a displacement device for the bending edge,

FIG. 6 a further cross-sectional view of the swivel bending machine with the displacement device for the bending edge,

FIG. 7 a further cross-sectional view through the swivel bending machine with a rotating device with a first and second bending edge,

FIG. 8 a further cross-sectional view of the swivel bending machine with the rotating device,

FIG. 9 a further cross-sectional view through the swivel bending machine for producing a hollow fold and

FIG. 10 a block diagram of a sheet bending process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a front view of a swivel bending machine 100 for bending flat metal sheets 103, such as steel sheets. For this purpose, the swivel bending machine 100 comprises a stable and immovable lower beam 101 for supporting the sheet 103. A mechanically displaceable and movable upper beam 105 serves to clamp the supported sheet 103 on the lower beam 101. The sheet 103 is clamped immovably between the stationary lower beam 101 and the vertically movable upper beam 105. For this purpose, the upper beam 105 can be moved upwards and downwards in the direction of the arrow.

A sheet section 115 of the clamped sheet 103 protrudes (projects) between the lower beam 101 and the upper beam 105, which has an approximately triangular lateral cross-section. On the lower front side, the upper beam 105 has a wedge-shaped bending edge 107 as an upper beam tool. The sheet 103 is bent along this bending edge 107. This is done by a rotatably or pivotably mounted, plate-shaped bending beam 109, which bends the protruding sheet section 115 along the wedge-shaped bending edge 107. A bending bar 121 of the bending beam 109 lies flat against the protruding sheet section 115. During the rotary movement, the protruding sheet section 115 is bent accordingly by the bending bar 121, so that in a first bending step an angled end region with an acute angle can be formed on the sheet 103, which essentially corresponds to the angle of the bending edge 107.

FIG. 2 shows a cross-sectional view through the swivel bending machine 100. The sheet 103 is clamped between the lower beam 101 and the upper beam 105. The bending beam 109 is pivoted upwards during the first bending step, so that the protruding sheet section 115 is bent around the wedge-shaped bending edge 107. The pre-bent sheet section 115 is located between the bending bar 121 of the bending beam 109 and the upper side of the wedge-shaped bending edge 107. The bending angle achieved essentially corresponds to the acute angle of the wedge-shaped bending edge 107. The axis of rotation of the bending beam 109 runs in a geometrically defined area along the wedge tip of the bending edge 107. In this way, it is possible in the first bending step to produce the sheet section 115 of the sheet 103 at an acute angle.

The bending bar 121, which is rectangular in cross-section, forms a stop edge for the sheet section 115 and additionally reinforces the bending beam 109. The bending bar 121 is formed, for example, by a strip-shaped metal part that extends along the bending beam 109 and is arranged on its upper side. The sheet section 115 rests against the side surface of the bending bar 121 during bending.

FIG. 3 shows a further cross-sectional view through the swivel bending machine 100. The bending beam 109 is in its original position here. After the previous bending step, the sheet 103 is (pre-)bent at an acute angle in the profile of the wedge-shaped bending edge 107. The swivel bending machine 100 comprises a movement device 111 for moving the wedge-shaped bending edge 107 out of the pre-bent section in the opposite wedge direction. This releases the bent wedge-shaped gap between the bent sheet section 115 and the remaining sheet 103.

The wedge-shaped bending edge 107 is moved out of the bent area by a lifting movement of the movable upper beam 105 in conjunction with a rotating movement of the upper beam 105. For this purpose, the swivel bending machine 100 comprises both a rotating device 113 for rotatably supporting the upper beam 105 and a displacement device 123 for vertically moving the upper beam 105. The rotating device 113 is formed by a rotatable bearing along the longitudinal axis of the upper beam 105. The bending edge 107 can thus be moved interpolated, so that the position of the bending edge 107 can always be brought into an optimum position, in particular for clamping the sheet. This can be done in a fully controlled process.

In general, however, the rotating device 113 can also be realized in other ways. Furthermore, the bending edge 107 can also be removed from the region of the pre-bent sheet section by other means.

FIG. 4 shows a further cross-sectional view through the swivel bending machine 100 with the bending edge 107 of the upper beam 105 moved back and the bending beam 109 folded up completely after the second bending step has been carried out. The rotatably mounted and moved back bending edge 107 is positioned during the second bending step so that it touches the sheet 103 on its upper side, so that the latter is fixed against the lower beam during the second bending step.

The rotatable bending beam 109 is in a vertical and upwardly rotated position, so that it has produced a hollow fold 125 from the pre-bent sheet section 115 with the bending bar 121. In the process, the sheet section 115 of the sheet 103, which was previously only bent to an acute angle, was completely folded over. In this way, a hollow fold 125 can be produced from the pre-bent sheet 103 at the bending edge 107, in which the sheet 103 is bent at an angle of approximately or exactly 180°.

By bending the sheet using the bending beam 109 and simultaneously fixing it against the lower beam using the wedge-shaped bending edge 107, the hollow fold 125 can be produced with a high degree of accuracy.

FIG. 5 shows a further cross-sectional view through the swivel bending machine 100 with a further embodiment of a movement device 111 for the bending edge 107. The upper beam 105 is not only vertically movable, but is also mounted so as to be displaceable in the horizontal direction along grooves 117, which form a displacement device 123 for linear extraction of the wedge-shaped bending edge 107 as a movement device 111.

The upper beam 105 can thus be displaced horizontally in the grooves 117. In this way, the bending edge 107 can be quickly pulled out of the bent area after the first bending step has been carried out and reset horizontally so that the sheet 103 can then be bent further. In the process, the wedge-shaped bending edge 107 can either slide along the surface of the sheet 103 with slight pressure or can first be lifted from the sheet by a slight vertical opening movement of the upper beam, pulled out of the bent area and bent back into contact with the upper side of the sheet 103 by a subsequent closing movement to clamp the sheet against the lower beam 101 again.

In this way, the area between the pre-bent sheet section 115 and the remaining sheet 103 is exposed without the sheet having to be repositioned. In general, however, the displacement device 123 can also be realized in other ways.

FIG. 6 shows a further cross-sectional view through the swivel bending machine 100 with the bending edge 107 of the upper beam 105 retracted. The rotatable bending beam 109 is in a vertical and upwardly folded position, so that it produces a hollow fold 125 from the previously bent sheet section 115 by means of the bending bar 121.

The bending bar 121 can advantageously comprise a fixed or adjustable crowning 127, which compensates for deflection of the bending bar 121 and the bending beam 109 during the bending process. For this purpose, the bending bar 121 can, for example, be slightly thicker in the center than at the edges. As a result, the bending bar 121 is curved out in the middle in relation to the edge areas in order to produce the hollow fold 125 evenly over the entire length. The crowning 127 is formed by a convex profile of the bending bar 121.

FIG. 7 shows a further cross-sectional view through the swivel bending machine 100 with a rotating device 113 for rotating the wedge-shaped bending edge 107 out of the pre-bent section 115 as a movement device 111. The upper beam 105 is rotatably mounted along the longitudinal axis by the rotating device 113.

The upper beam 105 has a first and a second bending edge 107-1 and 107-2. Depending on the angle of rotation of the upper beam 105, either the first bending edge 107-1 or the second bending edge 107-2 can thus be used to bend the sheet 103. Due to the freely positionable and rotatable upper beam 105, a multiple tool system with several bending edges 107-1 and 107-2 can be realized.

FIG. 8 shows a further cross-sectional view through the swivel bending machine 100 with the rotating device 113. The rotatable bending beam 109 is in a vertical position, so that it also produces a hollow fold 125 from the previously bent sheet section 115 by means of a rotary movement of the bending beam 109.

FIG. 9 shows a further cross-sectional view through the swivel bending machine 100 for producing a hollow fold 125. The rotatable bending beam 109 can be moved beyond the vertical position so that a closed hollow fold 125 can be produced by the bending bar 121 with a bending angle of >180°, depending on the sheet thickness, bending radius and leg length.

In general, the rotatably mounted bending beam 109 can have a swivel range of more than 180°, starting from its vertical downward position, in order to produce a parallel hollow fold. This overbending can compensate for the different springback rates of the various materials.

FIG. 10 shows a block diagram of a sheet bending process according to the invention, in which the steps (A) to (E) of the claimed sheet bending method already explained above are carried out in linear sequence.

All the features explained and shown in connection with individual embodiments of the invention can be provided in different combinations in the object according to the invention in order to realize their advantageous effects at the same time.

All process steps can be implemented by devices that are suitable for executing the respective process step. All functions performed by the features in question can characterize a process step of a process in an analogous manner.

The scope of protection of the present invention is given by the claims and is not limited by the features explained in the description or shown in the figures.

Claims

1. A swivel bending machine (100) for producing a hollow fold on a sheet (103) with: a lower beam (101) for supporting the sheet (103),an upper beam (105) with a wedge-shaped bending edge (107) for clamping the sheet (103) between the upper beam (105) and the lower beam (101),a rotatable or pivotable bending beam (109) for bending the sheet section (115) of the sheet (103) protruding be-tween the upper beam and the lower beam in a first bending step along the wedge-shaped bending edge (107) to an acute angle, anda movement device (111) for moving the wedge-shaped bending edge (107) out of the sheet section (115) pre-bent to an acute angle, wherein the swivel bending machine (100) is set up to further bend the sheet section (115) pre-bent into an acute angle into a hollow fold (125) in a second bending step with further actuation of the bending beam (109) between the bending beam (109) and the lower beam (101), while the sheet (103) is fixed against the lower beam by the wedge-shaped bending edge (107).

2. The swivel bending machine (100) of claim 1, wherein the movement device (111) comprises a displacement device (123) for linearly pulling out the wedge- shaped bending edge (107).

3. The swivel bending machine (100) of claim 1, wherein the movement device (111) comprises a rotating device (113) for turning out or swiveling out the wedge-shaped bending edge (107).

4. The swivel bending machine (100) of claim 3, wherein the rotating device (113) comprises a plurality of bending edges (107-1, 107-2).

5. The swivel bending machine (100) of claim 1, wherein the bending beam (109) comprises a bending bar (121) for bending the sheet section (115).

6. The swivel bending machine (100) of claim 5, wherein the bending bar (121) or the bending beam (109) comprises a crowning (127) for uniformly producing the hollow fold (125).

7. The swivel bending machine (100) of claim 6, wherein the bending bar (121) has a profile which is vertically crowned in the longitudinal direction of the machine.

8. A sheet bending method for producing a hollow fold (125) on a sheet (103) with a swivel bending machine of claim 1, comprising the steps of: (A) Placing a sheet (103) with a sheet section (115), which is initially to be pre-bent to an acute angle, on a lower beam (101) of the swivel bending machine (100),(B) clamping of the sheet between an upper beam (105) having a wedge-shaped bending edge (107) and the lower beam (101),(C) bending of a sheet section (115) protruding between the upper beam and the lower beam by means of the bending beam (109) in a first bending step along the wedge-shaped bending edge (107) to an acute angle,(D) moving the wedge-shaped bending edge (107) out of the sheet section (115) pre-bent to an acute angle, and(E) further bending of the sheet section (115) in a second bending step into a hollow fold (125) by further swiveling of the bending beam (109), while the sheet (103) is fixed against the lower beam (101) by means of the wedge-shaped bending edge (107).

9. The sheet bending method of claim 8, wherein the wedge-shaped bending edge (107) is moved out of the pre-bent sheet section (115) in the opposite wedge direction by a movement device (111).

10. The sheet bending method of claim 9, wherein the wedge-shaped bending edge (107) is pivoted out or pulled out of the pre-bent sheet section (115).

11. The sheet bending method of claim 8, wherein a deflection of the bending beam (109) and or the bending bar (121) during the first or second bending step is compensated by a crowning (127).