EP0535361A2 - Sheet feeder - Google Patents

Abstract

In a sheet feeder for sheet-processing machines, in particular sheet-fed printing machines, having a pile table (2) for receiving a main pile (4), which pile table (2) can be raised and/or lowered by means of a main hoist (3), and having a nonstop device with at least one, preferably two, supporting rack(s) (13) for receiving a residual pile (4a) from the pile table (2), on which subsequently there can be received a new pile, onto which the residual pile (4a) can be deposited, which supporting racks (13) lying laterlly opposite one another being retractable and extendible by means of a rack drive device (18), can be received in grooves (5a) of the pile table (2) and can be raised and lowered by means of an auxiliary hoist (10), high functional reliability and freedom from disruption can be achieved in that there are provided in the region of at least one rack bar (14) contact sensors (22, 23) one of which faces upwards and one downwards and with the aid of which the reception of the residual pile (4a) by the nonstop device and the provision of a new pile (4) below the residual pile (4a) are detectable. <IMAGE>

Description

The invention relates to a sheet feeder for sheet-processing machines, in particular sheet-fed printing machines, with a stacking table which can be raised or lowered by means of a main elevator for receiving a main stack and with a non-stop device with at least one preferably two opposite, retractable and extendable by means of a computing drive device, in grooves of the stacking table, which can be lifted or lowered by means of an auxiliary elevator, for taking over a remaining stack from the stacking table, on which a new stack can subsequently be picked up, onto which the remaining stack can be placed.

A sheet feeder of this type is known for example from DE 39 22 803 A1. With this known arrangement, automation of the stack change is aimed at. The publication mentioned does not, however Recognize facilities for the safe determination of the takeover of the remaining batch by the non-stop facility or the provision of a new batch. In the absence of such facilities, incorrect operation and thus malfunctions can occur. The known arrangement therefore proves to be not safe and reliable enough.

Proceeding from this, it is therefore the object of the present invention to improve a sheet feeder of the generic type while avoiding the disadvantages of the known arrangements with simple and inexpensive means so that a high level of functional reliability and freedom from interference are achieved.

This object is achieved in that at least two accumulation sensors are provided in the area of at least one rake bar, one of which points upwards and one downwards and with the aid of which the takeover of the remaining stack by the non-stop device and the provision of a new stack can be detected are.

With these measures, self-control of the takeover of the remaining stack by the non-stop device or the resetting of the part of the remaining stack that is still available after provision of a new stack to the new main stack is advantageously possible, as a result of which a high level of functional reliability and freedom from interference can be achieved. For example, the main elevator, instead of the retractable screen arrangement the auxiliary elevator can be clocked in the stroke direction by means of a button scanning the top of the stack, and can be driven in the overdrive direction in the lowering direction when the overrun sensor faces upward. When the downward-facing sensor comes into contact with the new stack provided, the computing extension process can be initiated.

The run-up sensors can advantageously be designed as blowing nozzles, to which blowing air can be applied, the pressure on the supply side of which can be sensed. These measures result in a highly robust arrangement that is insensitive to dust and dirt. This also ensures that markings on the adjacent sheet are not made.

At least two rake rods can expediently each have an axial blind bore which can be blown with air and from which a radial bore extends upwards or downwards. The use of two blowing nozzles, which can be acted upon separately, simplifies signal reception and thereby increases safety and reliability. The distribution of these two blowing nozzles, which can be acted upon separately, over two rake bars can facilitate production.

In a further development of the higher-level measures, the non-stop device can be provided with every counter-rake assigned to each supporting rake, which can be adjusted at least when the assigned supporting rake is extended to the stack edge facing it, which can be switched on or off by means of a counter-holder drive device and by means of a sequential circuit which can be controlled by the run-up detectors the rake extension movement can be activated are. In this way it can be prevented in a simple manner that the stack side edge is displaced in the course of the computing extension movement. Each counter-holder can expediently be assigned a clamping device by means of which it can be ascertained in the retracted state and which can be activated by means of a sequential circuit which can be controlled by the run-up detectors before the computing extension movement. This can simplify the design of the drive devices assigned to the counterholders.

Another expedient embodiment can consist in that the counterholders bridge the gap between the main and auxiliary stacks and are provided with side sensors assigned to the main and auxiliary stacks, by means of which an actuating device for lateral stack adjustment can be controlled. This ensures that there are no discontinuities in the area of the stack side edge when changing the stack.

Further expedient further developments and advantageous refinements of the superordinate measures result from the following description of a preferred exemplary embodiment with reference to the drawing in conjunction with the remaining subclaims.

Figur 1

eine Frontansicht des erfindungsgemäßen Bogenanlegers teilweise im Schnitt,

Figur 2

eine Draufsicht auf die Anordnung gemäß Figur 1,

Figur 3

ein Beispiel für mit Blasluft beaufschlagbare Auflaufdetektoren in schematischer Darstellung,

Figur 4

den Betriebszustand vor Übernahme des Reststapels durch die Nonstop-Einrichtung in Form einer schematischen Teilansicht und

Figur 5

den Betriebszustand vor dem Aufsetzen des Reststapels auf dem darunter bereitgestellten, neuen Hauptstapel in Form einer schematischen Teilansicht.

The drawing shows:

Figure 1

2 shows a front view of the sheet feeder according to the invention, partly in section,

Figure 2

2 shows a plan view of the arrangement according to FIG. 1,

Figure 3

1 shows an example of emergence detectors to which blow air can be applied in a schematic illustration,

Figure 4

the operating state before taking over the remaining stack by the non-stop device in the form of a schematic partial view and

Figure 5

the operating state before placing the remaining stack on the new main stack provided below in the form of a schematic partial view.

The sheet feeder on which FIGS. 1 and 2 are based has a portal-shaped frame 1, in which a stacking table 2 which can be raised and lowered is arranged. This is suspended from a main elevator 3 indicated by lifting chains. The stacking table 2 can be lowered to the floor level and, in the lowered state, can be loaded with a sheet stack 4 indicated by a dashed outline. This rests on a pallet 5, which can be rolled up onto the stacking table 2 here. For this purpose, a roller conveyor 6 running transversely to the longitudinal axis of the feeder is provided, the central section 6a of which is mounted on the stacking table 2. The upstream and downstream sections of the roller conveyor are arranged on the corridor side.

By actuating the roller conveyor section 6a mounted on the stacking table 2, a lateral adjustment of the stack 4 is also possible here. In the example shown there is provided a side stop 8 adjustable by means of an associated drive device 7, against which the stack 4 can be moved by means of the roller conveyor section 6a. The side stop 8 is drawn here in the extended, inactive waiting position.

In the upper area of the frame 1, a separating and conveying unit (not shown here), for example in the form of a suction head known per se, is provided, by means of which the uppermost sheet can be removed from the stack underneath and transported away. The continuously decreasing stack height is compensated for by lifting the stacking support in cycles. The clocking is accomplished by a button indicated in FIGS. 4 and 5 at 9, scanning the top edge of the stack.

The stack 4 received on the stacking table 2 is referred to below as the main stack. As soon as this stack has been processed to a predetermined remaining height, it is transferred as a remaining stack 4a to a non-stop device in order to lower the then empty stacking table 2 and to be able to load it with a new main stack 4. During this time, the remaining stack 4a is processed further. The docking operation therefore does not have to be interrupted. The stacking table 2 equipped with a new main stack 4 is then raised to such an extent that the rest of the remaining stack 4a which is still present can then be placed on the new main stack 4 and combined with it.

The above-mentioned non-stop device comprises an auxiliary elevator 10 indicated by its lifting chains Suspended lifting platform 12 guided on a vertical guide 11, which, as can best be seen from FIG. 2, has two frames 12a flanking the feeder frame 1 on the side, which are connected to one another by a yoke 12b running in the area of the front in the sheet conveying direction. On each frame 12a, a supporting rake 13, which can be moved transversely to the longitudinal axis of the feeder, is accommodated, the rake bars 14 of which can be brought from the lateral waiting position on which the figures 1 and 2 are based to a working position below the auxiliary stack 4a, indicated by dashed lines in Figure 1, and vice versa. For this purpose, the pallet 5 which can be received on the stacking table 2 is provided with grooves 5a which are arranged at a distance from the rake bars 14 and also run transversely to the longitudinal axis of the feeder. As soon as the pallet 5 with its grooves 5a reaches the level of the lifting platform 12 which is in a lower stop position and the supporting rakes 13 accommodated thereon, these are moved into the grooves 5a with their rake bars 14. Subsequently, the lifting platform 12 is raised further under the command of the button 9 which scans the upper edge of the auxiliary stack 4a which is now picked up on the supporting rake 13. The stacking table 2 thus unloaded is lowered to the floor level.

The two supporting rakes 13 are received on a respectively assigned carriage 15, which is slidably supported by rollers 16 on longitudinal guides 17 arranged along the front and rear spars of the assigned frame 12a and can be pushed back and forth by means of an assigned drive unit 18. The drive unit 18 is simply designed here as a drag chain that can be driven by means of a geared motor. To achieve a High stability of the rake bars 14, these are clamped with their rear end in a flexurally and torsionally rigid support 19, which is designed to bridge the lateral end shields of the respectively assigned carriage.

After the stacking table 2 is equipped with a new main stack 4 and this is provided below the auxiliary stack 4a, the supporting rakes 13 are withdrawn from the working position indicated by the dashed line in FIG 4 is discontinued. In order to prevent the remaining stack 4a or the upper region of the main stack 4 from moving when the supporting rakes 13 are extended, a counter holder 20 is assigned to each supporting rake 13. The counterholders 20 are also accommodated on the lifting platform 12 and can be placed on the stack side edge facing the respectively assigned support rake 13 when the support rakes 13 are extended. The counterholders 20 contain pressure plates which can be adjusted to the side of the stack and are fastened to the piston rod of a cylinder-piston unit forming an associated drive device 21, since the lifting platform 12 is received on the associated frame 12a. The cylinder-piston assemblies forming the counter-holder drive devices can be provided with double-acting pistons with different effective areas, so that a slow movement can be carried out with double-sided action and a fast movement with one-sided action. This makes it possible to design the hiring process in several stages by first driving forward in high speed and then that last piece is slowly covered. Likewise, the return movement can take place in an overdrive.

In order to determine the takeover of the remaining stack 4a by the carrying rakes 13 or the arrival of a new main stack 4 below the remaining stack 4a, so that further operations can be initiated automatically as a function thereof, are in the area of the carrying racks 13, as can best be seen in FIG is provided, two accumulation sensors 22, 23, of which here the accumulation sensor 22 is arranged upwards and the accumulation sensor 23 pointing downwards. The run-up sensors 22, 23 are designed here as air nozzles which can be acted upon and which are closed when the relevant carrying rake 13 opens onto a surface above or below it, as a result of which the pressure in the associated supply line 24 or 25 increases. This pressure increase can be used as a control signal.

In order to form the blow nozzles forming the run-up sensors 22, 23, surface bars 14 assigned to each of them are provided here, each with an axial blind bore 27, one of which is connected via the assigned supply line 24 or 25 to a compressed air source, here in the form of the compressed air network 26, one of which is a radial bore 28 goes off, which opens up in one case and down in the other case. In the example shown, the two run-up sensors 22, 23 are distributed over two computing bars 14. These can belong to the same supporting screen 13. However, it would also be conceivable to distribute the two run-up sensors 22, 23 over both supporting rakes 13. It would also be possible to have both overrun sensors in the area of a single one To accommodate rulers, although the design shown is simpler to manufacture. Compressed air supply is also easier if both overrun sensors, as shown, belong to the same supporting screen.

The pressure in the supply lines 24, 25 is received by measuring lines 29 branching therefrom and fed to a downstream signal processing device 30, from which the desired control functions can be carried out, as indicated by the input arrows 31.

The depth of the grooves 5a of the pallet 5 is, as can best be seen from FIG. 4, greater than the diameter of the rake bars 14. When the rake bars 14 are inserted into the grooves 5a, both blow nozzles forming the run-up sensors 22, 23 initially remain open. Accordingly, the same low pressure prevails in both supply lines 24, 25. After completion of the running-in process, as already mentioned above, instead of the stacking table 2, the lifting platform 12 with the carrying rakes 13 is clocked up under the control of the button 9. For this purpose, instead of the main elevator 3 assigned to the stacking table 2, the auxiliary elevator 10 assigned to the lifting platform 12 is actuated by the button 9. By lifting the lifting platform 12, the rake bars 14 of the supporting rake 13 run onto the underside of the stack previously resting on the pallet 5 and now to be accommodated as an auxiliary stack 4a on the supporting rake 13, as a result of which the blowing nozzle which forms the upward-pointing casserole sensor 22 and closes upward and closes becomes. The pressure in the associated supply line rises accordingly 24 on. This signal can be used as a control signal for initiating the lowering of the stacking table 2. For this purpose, the main elevator 3 assigned to it can be controlled by the signal processing device 30 in such a way that it is lowered to the corridor level at high speed. Of course, braking and a transition to a slower speed is possible shortly before the end position is reached.

The blowing nozzle forming the upward-pointing casserole sensor 22 and opening upward is kept closed as long as the auxiliary stack 4a rests on the supporting rake 13. The blowing nozzle forming the downward-pointing casserole sensor 23 is initially open, as can be seen in FIG. While the remaining stack 4a received on the carrying rake 13 is being processed, a new main stack 4 is placed on the lowered stacking table 2, as was explained in more detail above. Then the stacking table 2 is raised. This can be done by hand control. The lifting movement can also initially take place in overdrive until the position on which FIG. 5 is based is reached just below the carrying rake 13. The last, short distance can be covered in a slow gear. The switch from overdrive to slow gear can be carried out automatically using suitable sensors.

In the intermediate position on which FIG. 5 is based, the blowing nozzle which forms the downward-pointing emergence sensor 23 is still open. If the main stack 4 is now raised further, its top runs on the Underside of the support rake 13, whereby the downward-opening blow nozzle forming the downward-pointing casserole sensor 23 is also closed. Accordingly, there is now also a pressure increase in the associated supply line 25, which can be used as a control signal for positioning the counter-holder 20 and for extending the support rake 13. It is also conceivable to initiate these processes as a function of a further condition, for example of a certain remaining stack height, so that the same conditions are always present. The desired residual stack height can be sensed by means of a sensor, the output signal of which can be linked to the output signal of the downward-pointing accumulation sensor 23, for example by an AND gate.

To initiate the rake extension process, the counterholders 20 are first placed on the side of the stack, as already explained above. For this purpose, the associated drive devices 21 are controlled in such a way that the plate-shaped counterholders 20 run onto the respectively facing side of the stack. The counterholders 20 are then locked in this position. For this purpose, a clamping cylinder 32 can be assigned to each of the cylinder-piston units forming the drive devices 21, which can be controlled via a sequential circuit integrated in the signal processing device 30 after activation of the drive devices 21. The drive devices 18 assigned to the carrying rakes 13 can then be activated in the extension direction via a further sequential circuit integrated in the signal processing device 30. The exit speed can include several levels. As long as the rake bars reach deep into the stack, the extension speed can be selected depending on the material. At least from the point in time at which the rake bars 14 emerge from the stack, the extension movement can be continued at high speed. For this purpose, the assigned drive devices can simply be provided with a frequency converter.

The counterholders 20, as can best be seen in FIG. 5, are designed in such a way that they bridge the gap caused by the support rakes 13 between the auxiliary stack 4a and the main stack 4 provided underneath and are accordingly located both below and above the support rakes 13 Have support surfaces with which they can start on the main stack 4 or auxiliary stack 4a. As a result, lateral slipping of both the main stack 4 and the auxiliary stack 4a can accordingly be prevented. The counterholders 20 are of course designed in such a way that a collision with the neighboring rake bars 14 does not occur. In the exemplary embodiment shown, the counterholders 20 are provided with a drive-through recess assigned to the respective adjacent rake bar 14. The counterholders 20, as can be seen further in FIG. 5, are provided with the main stack 4 and the side sensors 33 associated with the auxiliary stack 4a, by means of which an above-mentioned device for lateral stack adjustment can be controlled, whereby when the main stack 4 and auxiliary stack 4a are combined Discontinuities in the stack side edge can be avoided.

Claims (12)

Sheet feeder for sheet-processing machines, in particular sheet-fed printing machines, with a stacking table (2) which can be raised or lowered by means of a main elevator (3) for receiving a main stack (4) and with a non-stop device with at least one, preferably two laterally opposite one another, by means of a computing drive device (18) retractable and extendable, in the grooves (5a) of the stacking table (2), which can be raised or lowered by means of an auxiliary elevator (10), to carry a residual stack (4a) from the stacking table (2), on which subsequently a new stack on which the remaining stack (4a) can be placed, characterized in that at least two run-up sensors (22, 23) are provided in the area of at least one rake bar (14), one of which points upwards and one downwards and with the help of which the takeover of the remaining stack (4a) by the non-stop device and the provision of a new stack (4) below are detectable within the remaining stack (4a). Sheet feeder according to claim 1, characterized in that the run-up sensors (22, 23) are designed as blowing nozzles, to which blowing air can be applied, the feed-side pressure of which can be sensed. Sheet feeder according to claim 2, characterized in that the blowing nozzles are each designed as a radial bore (28) extending from an associated axial blind bore (27). Sheet feeder according to claim 2 or 3, characterized in that the blowing nozzles forming the two run-up sensors (22, 23) are arranged on different rake bars (14), preferably the same supporting screen (13). Sheet feeder according to one of the preceding claims, characterized in that the main elevator (3), instead of which the auxiliary elevator (10) can be clocked in the stroke direction by means of a button (9) scanning the top edge of the stack when the supporting rake arrangement is retracted, when the contact sensor of the upward facing sensor (22 ) can be activated at high speed in the lowering direction. Sheet feeder according to one of the preceding claims, characterized in that the contact rake extension process can be initiated in the event of contact of the downward opening sensor (23). Sheet feeder according to one of the preceding claims, characterized in that the non-stop device is provided with at least one counter-holder (20), which is assigned to each supporting rake (13) and can be adjusted at least when the supporting rake (13) is extended against the stacking edge facing the latter associated drive device (21) can be switched on and off and activated by means of a sequential circuit which can be controlled by the run-up sensors (22, 23) before the computing extension movement. Sheet feeder according to claim 7, characterized in that the counter-holder (20) can be locked in the retracted state by means of a clamping device (32) which can be activated by means of a sequential circuit which can be controlled by the overrun sensors (22, 23) before the computing extension movement. Sheet feeder according to one of the preceding claims, characterized in that the counterholders (20) bridge the gap between the main and auxiliary stacks and are provided with side sensors (33) assigned to the main and auxiliary stacks, by means of which an actuating device for lateral adjustment of the stack is controllable. Sheet feeder according to one of the preceding claims, characterized in that two opposite, oppositely movable, lateral supporting rakes (13) are provided, which are received on a lifting platform (12) suspended from the auxiliary elevator (10) which has side frames (12a) assigned to the supporting rakes (13) and which are connected to one another by a front yoke (12b). Sheet feeder according to one of the preceding claims, characterized in that the stacking table (2) is provided with a section (6a) of a roller conveyor (6) which is preferably preceded and arranged by further sections arranged on the corridor side and on which the grooves (5a ) Pallet (5) is receivable. Sheet feeder according to one of the preceding claims, characterized in that the depth of the grooves (5a) on the stacking table is greater than the diameter of the supporting rake bars (14).

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