EP0017029B1 - Device for cutting sheet metal and stacking cut-off blanks - Google Patents

Abstract

The apparatus comprises a sheet metal shears at a cutting station which station is provided with a lifting table 13 which is vertically adjustable, is used for cutting off small sections of sheet metal from a sheet and also is used for stacking these sections on a pallet 15. This lifting table extends through a cut-out side wall 5 for the shears and thus permits the shifting of an already piled-up stack 16 away from the shears, and then upwardly so that an adjacent stack 16a may be piled up neatly in spaced apart relation with stacks separated from each other by at least the thickness of the cut-out side wall. The continuing movement of the lifting table 13 after erecting the first stack 16 causes a small drop at the cut-off sections which are placed on the pallet 15, so that an orderly piled-up stack 16a develops. As the height of the stack increases the lifting table is gradually lowered until the predetermined height of the stack is reached.

Description

The present invention relates to a device for cutting metal sheets and for stacking the separated metal sheet sections. The device has sheet metal scissors with a sheet metal feed table, on the rear edge of which a fixed lower knife is arranged, which cooperates with an upper knife pivotably mounted between two side stands. In the plane of the sheet metal feed table, a support device which is displaceable in its plane perpendicular to the cutting members is arranged behind the cutting point, and a height-adjustable lifting table is arranged beneath it, which takes up the separated sheet metal sections after the support device has been withdrawn. At a certain, adjustable distance behind the lower knife, a stop is provided against which the edge of the sheet to be cut rests so as to determine the width of the sheet section. After the cut, the severed sheet metal strip lies on the support device and then, after withdrawal thereof, falls down onto a stacking surface, so that a stack of sheet metal sections is gradually formed.

It is of course desirable that this stack is stacked evenly and orderly in order to avoid subsequent, time-consuming and tedious manual sorting of the stack. This can be achieved by keeping the falling distance of the sheet metal section as small as possible. The height-adjustable lift table serves this purpose. In practice, a pallet can be used as a stacking surface, which is arranged on the lifting table. The lifting table is located directly behind the lower knife and is moved into an upper end position at the start of work, so that the surface of the pallet lies below the plane of the sheet feeding table by a certain small amount, depending on the thickness of the sheets to be cut. After a few metal strips have been cut off and stacked on the pallet, the lifting table is lowered somewhat in order to bring the surface of the stack formed in this way back some distance below the level of the feed table. This process is repeated until the lifting table has reached its lower end position or the stack has reached its intended height. The lowering of the lifting table can be done either manually or automatically, for example with the help of a light barrier, step by step or continuously. This ensures that the separated sheet metal sections always cover only a small distance in free fall, so that a clean, even stack is formed.

A device with a lowerable stacking table has become known from DE-A1-2 651 197. This uses a vacuum or magnetic stacking device and a conveyor and provides a stacking table that can be extended laterally and moved in the longitudinal direction of the sheets. There are significant disadvantages with the known devices when small sheet metal sections are produced. A stack of small sections takes up only a small part of the surface of a pallet, but it would be desirable to arrange several such stacks side by side. However, as soon as the first stack has been completed, the lifting table can no longer be raised, since the existing stack would hit the support device. So far, one has been forced to either leave the capacity of the pallet unused by forming only one stack per pallet, or to accept that a second stack next to it fails because the separated sheet metal sections leave a relatively large distance in the open Have to cover the case.

It is the object of the present invention to avoid this disadvantage and to propose a device with which several cleanly stacked stacks of separated sheet metal sections can be erected next to one another.

A device of the type mentioned at the beginning is assumed. According to the invention, this device is characterized in that the lifting table is stationary and longer than the lower knife and extends from the one side stand of the metal shears along the cutting point through a recess of the other side stand which allows the lifting table to be raised and lowered, whereby there is a stacking and transporting element which can be moved transversely to the sheet metal feed at the lifting table to form several sheet metal stacks.

After forming the first stack, it is moved from the area of the support device to a position outside the side stand with the lift table lowered, so that the lift table together with the stack and transport element with its unoccupied surface for receiving a new stack can be lifted up to the support device. The surface of the lifting table can be provided with a roller conveyor, and a conventional pallet can be placed on this roller conveyor.

• Fig. 1 eine schematische, teilweise geschnittene Seitenansicht,
• Fig. 2 + 3 schematische Teilansichten von hinten, und
• Fig. 4-14 die verschiedenen Phasen des Ablegens der abgetrennten Blechabschnitte.

In the following an embodiment of the device according to the invention is described in more detail with reference to the accompanying drawings. The drawings show:

• 1 is a schematic, partially sectioned side view,
• Fig. 2 + 3 schematic partial views from behind, and
• Fig. 4-14 the different phases of depositing the separated sheet metal sections.

In Fig. 1, a pair of guillotine shears is shown, which is provided with a sheet metal feed table 1, on the rear edge of which a fixed lower knife 2 is attached. These parts are stored in a machine frame 3 which is delimited on both sides by side walls 4 and 5. A hold-down device 6 ensures that a metal sheet to be cut cannot move during the cut. The Fixed lower knife 2 works together with an upper knife 7 which is mounted in a knife bar 9 which can be pivoted about an axis 8. Behind the lower knife 2, in the plane of the feed table 1, a displaceable support device 10 is arranged, which is also provided with displaceable stops 11.

The support device can consist of a number of parallel rods which extend away from the lower knife 2 towards the rear. The function of the support device and the stops will be discussed in more detail below.

One side wall 5, in FIGS. 2 and 3, is perforated, so that a free passage 12 is formed behind the lower knife 2. The height of the passage 12 corresponds approximately to the height of the feed table 1. Behind the cutting point there is a lifting table 13, the design of which is not discussed in detail here. As can be seen from FIGS. 2 and 3, it extends from the continuous side wall 4 across the width of the guillotine shears and through the passage 12 somewhat beyond the shears. On its upper side it is provided with a number of rollers 14 which are rotatable about axes running perpendicular to the lower knife 2. A pallet 15 placed on the roller conveyor thus formed can thus be displaced parallel to the lower knife 2, specifically within the scissors along the lower knife 2 and out of the scissors, through the passage 12. The pallet 15 is used to hold stacks 16 of separated sheet metal sections.

The device works as follows:

The lifting table 13 with the pallet 15 attached is raised to an upper end position in which the surface of the pallet 15 lies just below the cutting point or below the support device 10. Then the sheet of metal to be cut is inserted until its edge lies against the preset stop 11. The sheet metal section to be separated is supported by the support device 10. After the hold-down device 6 has been actuated, the cut is made with the aid of the two knives 2 and 7, so that the separated sheet metal section 17a lies on the support device 10. After the cut, the support device 10 is pulled backwards, the stop 11 remaining in place. As a result, the sheet metal section 17a falls down onto the pallet 15, whereby it only has to cover a short distance in free fall because the pallet 15 has been brought almost to the height of the lower knife 2 by the lifting table 13. The support device 10 is then brought forward again into its starting position, so that the next sheet metal section can be supported and separated in a corresponding manner.

After a few cuts, when the stack 16 has reached a certain height, the lifting table 13 and thus the pallet 15 must be lowered somewhat. This can be done manually or automatically, e.g. with the help of a light barrier that monitors the height of the stack 16 and causes the lifting table 13 to be lowered when a limit value is reached. In this way, each cut sheet section 17a only has to cover an optimally short distance in free fall, so that a neatly stacked, orderly stack 16 is produced.

As soon as the lifting table 13 has reached its lower end position or when the stack 16 is piled up at the intended height, the pallet 15 is moved out of the guillotine shears on the rollers 14, after which the lifting table 13 can be moved back into its upper end position.

This situation is shown in Fig. 3. In addition to the stack 16, a further stack 16a can now be stacked, the distance between the two stacks 16 and 16a being limited by the thickness of the side wall 5.

The lifting of the lifting table 13 is easily possible since there is sufficient free space outside the scissors towards the top so that the stack 16 which has already been stacked up cannot hit anywhere.

In a corresponding manner, the second stack 16a is now piled up until it has reached its intended height. Since the lifting table 13 is then again in its lower position, the pallet 15 can again be laterally displaced by the width of the stack 16a plus the thickness of the side wall 5 in order to enable the lifting table 13 to be raised again. Depending on the width of the separated sheet metal sections, several stacks 16 can be stacked next to one another on the pallet 15, whereby it is always ensured that the sheet metal sections cover only a short distance in free fall, so that neat, cleanly layered stacks 16 are created. This ensures optimal use of space on the pallet 15. As soon as the pallet 15 is full, it is pulled out of the guillotine shears on the roller conveyor and can e.g. taken over by a forklift and fed to further processing.

• Fig. 4 Ein abgetrennter Blechabschnitt liegt auf der Stützeinrichtung 10 auf und berührt mit seiner Hinterkante den Anschlag 11. Die Palette 15 ist noch leer. Die Stützeinrichtung 10 wird nun in Pfeilrichtung nach hinten verschoben, wobei der Anschlag 11 an Ort und Stelle verbleibt.
• Fig. 5 Die Stützeinrichtung 10 ist in ihrer hinteren Endstellung und der Blechabschnitt 17b ist auf die Palette 15 hinuntergefallen.
• Fig. 6 Die Stützeinrichtung 10 wurde wieder nach vorne verschoben, und der nächste Blechabschnitt 17c ist abgetrennt worden. Er liegt gegen den Anschlag 11 an und ruht auf der Stützeinrichtung 10. Diese wird nun mitsamt dem Anschlag 11 in Pfeilrichtung nach hinten verschoben.
• Fig. 7 Der Blechabschnitt 17c liegt nun über einer freien Stelle auf der Palette 15, unmittelbar hinter dem Abschnitt 17b. Der Anschlag 11 wird angehalten, die Stützeinrichtung 10 jedoch in Pfeilrichtung weiterbewegt.
• Fig. 8 Die Stützeinrichtung 10 ist ganz nach hinten verschoben, und der Abschnitt 17c ist auf die Palette 15 hinuntergefallen, wo er hinter dem Abschnitt 17b ruht.
• Fig. 9 Stützeinrichtung und Anschlag sind wieder in ihre Ausgangsstellung gebracht worden, und der nächste, abgetrennte Blechabschnitt 17d liegt auf der Stützeinrichtung 10 auf. Diese wird mitsamt dem Anschlag 11 in Pfeilrichtung gegen hinten bewegt.
• Fig. 10 Sobald eine freie Stelle auf der Palette 15 erreicht ist, wird der Anschlag 11 angehalten, die Stützeinrichtung jedoch weiter nach hinten bewegt.
• Fig. 11 Die Stützeinrichtung 10 ist in ihrer hinteren Endstellung und der Abschnitt 17d ist auf die Palette 15 hinuntergefallen, wo er hinter dem Abschnitt 17c liegt.
• Fig. 12 Die Stützeinrichtung 10 samt dem Anschlag 11 ist wieder in die Ausgangslage gebracht worden. Der nächste, abgetrennte Blechabschnitt 17e liegt auf der Stützeinrichtung auf.
• Fig. 13 Die Stützeinrichtung 10 mitsamt dem Anschlag 11 ist nach hinten verschoben worden, bis der Abschnitt 17e über der letzten, in dieser Stapelreihe noch freien Stelle auf der Palette 15 angelangt ist. Der Anschlag 11 wird nun angehalten.
• Fig. 14 Die Stützeinrichtung 10 ist bei stillstehendem Anschlag 11 weiter zurückbewegt worden, und der Abschnitt 17e ist auf die Palette 15 gefallen, wo er hinter dem Abschnitt 17d ruht.

In the case of small sheet metal sections, it is expedient and in the sense of optimal use of the pallet not only to arrange a plurality of stacks 16, 16a etc. next to one another in the longitudinal extent of the knife 2, but also to stack a few stacks one behind the other. This process is outlined in Fig. 4-14 and can be explained as follows:

• Fig. 4 A separated sheet metal section lies on the support device 10 and touches the stop 11 with its rear edge. The pallet 15 is still empty. The support device 10 is now moved backwards in the direction of the arrow, the stop 11 remaining in place.
• Fig. 5 The support device 10 is in its rear end position and the sheet metal section 17b has fallen onto the pallet 15.
• Fig. 6 The support device 10 has been moved forward again, and the next sheet metal section 17c has been separated. It lies against the stop 11 and rests on the support device 10. This is now moved together with the stop 11 in the direction of the arrow to the rear.
• Fig. 7 The sheet metal section 17c is now over a free space on the pallet 15, immediately behind the section 17b. The stop 11 is stopped, but the support device 10 is moved further in the direction of the arrow.
• Fig. 8 The support device 10 is pushed all the way back, and the section 17c has fallen onto the pallet 15, where it rests behind the section 17b.
• Fig. 9 support device and stop have been returned to their starting position, and the next, separated sheet metal section 17d lies on the support device 10. This is moved together with the stop 11 in the direction of the arrow towards the rear.
• Fig. 10 As soon as a free place on the pallet 15 is reached, the stop 11 is stopped, but the support device is moved further back.
• Fig. 11 The support device 10 is in its rear end position and the section 17d has fallen onto the pallet 15, where it lies behind the section 17c.
• Fig. 12 The support device 10 together with the stop 11 has been brought back to the starting position. The next, separated sheet metal section 17e lies on the support device.
• Fig. 13 The support device 10 together with the stop 11 has been moved backwards until the section 17e has reached the last place on the pallet 15 that is still free in this stack row. The stop 11 is now stopped.
• Fig. 14 The support device 10 has been moved further back with the stop 11 stationary and the section 17e has fallen onto the pallet 15, where it rests behind the section 17d.

Now the whole cycle begins anew by placing the next sheet metal section on sheet section 17b already lying on pallet 15, the following sheet metal section on section 17c and so on. The four stacks 16 gradually grow, and the pallet 15, which is placed on the roller conveyor of the lifting table 13, is lowered somewhat. By alternately throwing off the separated sheet metal sections onto the four stacks 16 lying one behind the other, they grow simultaneously until they have reached their intended height. Now the pallet 15 can be moved laterally out of the guillotine shears, as has already been described above, and the next stack row can be set up in a corresponding manner.

This procedure allows an optimal use of the space available on the pallet 15, whereby it is always ensured that cleanly stacked stacks 16 are formed, since the sheet metal sections only have to cover a short distance in free fall.

Of course, the movements of the support device 10 and stop 11 can be controlled automatically, e.g. under the influence of an electronic NC control unit. If necessary, this can also be used to control the lifting and lowering movement of the lifting table 13.

The proposed device not only allows optimum use of space on the pallet 15 with simultaneous, orderly stacking, but also enables fast, safe work, since the subsequent manual rearrangement and straightening of the stack 16 can be completely dispensed with.

Claims (5)

1. A device for cutting sheet-metal plates and for stacking the separated sheet-metal sections (17) by means of sheet-metal shears, comprising a sheet-metal feed table, at the rear edge of which a fixed knife (2) is arranged cooperating with an upper knife (7) pivotably mounted between two lateral uprights (4, 5), a support device (10) arranged in the plane of the sheet-metal feed table downstream of the cutting area and being movable in the plane at right angles to the cutting members (2, 7), and a lifting table (13) arranged below the support device (10) and being adjustable in height and receiving the separated sheet-metal sections after the support device (10) has been withdrawn, characterised in that the lifting table (13) is laterally non-displaceable is longer than the lower knife (2) and extends from one lateral upright (4) to the sheet-metal shears along the cutting area through a recess (12) in the other lateral upright (5) so as to allow the lifting table (13) to be raised and lowered, stacking and transport means (15) movable transversely to the feed of sheet-metal being provided on the lifting table (13) for forming a plurality of sheet-metal stacks (16).

2. A device according to claim 1, characterised in that the surface of the lifting table (13) is provided with rollers (14) rotatable about axes extending at right angles to the lower knife (2).

3. A device according to claim 1 or 2, characterised in that a base support, for example a pallet (15), is mounted on the rollers (14) in order to receive the stacks (16).

4. A device according to claim 1, characterised in that stops (11) are provided which can be moved relative to the cutting area (2) together with the support device (10) or independently thereof.

5. A device according to claims 1 and 4, characterised in that the stop (11) is movable with the support device (10) in the feed direction of the sheet metal in stops having the width of a row of stacks so as to form rows of stacks in the feed direction of the sheet-metal.

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