Suction belt table

Abstract

Device for conveying a shingled stream of sheets to a sheet processing machine, comprising a conveying table (9) which has at least one continuously driven, air-permeable conveyor belt (26) which can be subjected to negative pressure on an underside of its upper belt (26) sliding over the conveying table (9) by a first suction chamber (28), a second suction chamber (29) and a third suction chamber (30), wherein the third suction chamber (30) is the last suction chamber upstream of the sheet processing machine (1) and suction air of different pressure levels can be supplied to it in sync with the sheet processing machine (1), characterized by that the third suction chamber (30) is preceded by a further suction chamber (41) to which suction air at different pressure levels can be supplied in sync with the sheet processing machine (1), that the third suction chamber (30) and the further suction chamber (41) can be subjected to high and low vacuum pressures in phase shifts by a common rotary valve (38), that the third suction chamber (30) and the further suction chamber (41) are arranged at a distance (a) from each other and that at the distance (a) a part of the second suction chamber (29) is arranged.

Description

[0001] The invention relates to a device for conveying a shingled arc stream to a sheet processing machine, in particular a printing press, according to the preamble of claim 1.

[0002] Such a device is known, for example, from DE 102 13 705 A1. This shows a conveying table consisting of three suction chambers arranged one behind the other, in which a first suction chamber can be pressurized with high vacuum, a second suction chamber with low vacuum and a third suction chamber with high vacuum, wherein the vacuum of the third suction chamber switches back and forth between a high vacuum and a low vacuum in sync with the sheet processing machine.

[0003] The problem with such conveyor tables is that during a lateral alignment phase of the first arc, the second arc of the arc stream no longer rests completely on the conveyor table in the area of ​​the second suction chamber with its scale length, so that the holding force exerted on the arc is reduced.

[0004] Further state of the art is represented by US 2010 / 0 276 868 A1, DE 10 2007 036 134 A1, GB 1 577 158 A and US 3 827 548 A.

[0005] The invention is based on the objective of creating a further device of this type, in particular one that securely holds the second arc of a shear stream.

[0006] The problem is solved according to the invention by a device having the features of claim 1.

[0007] A particular advantage of the invention is that the holding force can be specifically increased for the respective second arc of the shingle stream. This measure improves not only the positional stability during arc transport but also the separation behavior of the first arc from the second arc.

[0008] In an advantageous embodiment, the additional suction chamber according to the invention is arranged within the second suction chamber. It is advantageous if the additional suction chamber is spaced apart from the third suction chamber and if, within this space, suction air acts on the second arc, which corresponds in level to the constant negative pressure of the second suction chamber.

[0009] In an advantageous embodiment of the device according to the invention, it is provided that the additional suction chamber is supplied with suction air in cycles, wherein the cycle is phase-shifted relative to the cycle of the third suction chamber, in particular by approximately 180°.

[0010] In an advantageous embodiment, a rotary valve with two supply channels is provided for this purpose.

[0011] A particularly uniform load on the suction sources is advantageously achieved by providing a first suction source to generate the negative pressure for the first and the additional suction chamber, the second suction source to generate the negative pressure of the second suction chamber, and the third suction source to generate the negative pressure of the third suction chamber.

[0012] An embodiment of the invention is illustrated in the drawings and is described below. The drawings show... Fig. 1. A cross-section of a sheet-fed rotary printing press in a schematic representation, Fig. 2 a suction belt table in cross-section in schematic representation and Fig. 3a-d the suction belt table in an area facing the sheet processing machine upon arrival of a first sheet of a sheet stream at designated front marks

[0013] A sheet-processing machine 7, e.g., a printing press 1, has a feeder 2, at least one printing unit 3 or 4, and a delivery unit 6. The sheets 7 are taken from a stack of sheets 8 and fed singly or in batches via a feed table 9 to the printing units 3 and 4. These units each contain a plate cylinder 11, 12, as is known. The plate cylinders 11 and 12 each have a device for attaching flexible printing plates. In addition, each plate cylinder 11, 12 is assigned a device for semi- or fully automatic plate changing.

[0014] The stack of sheets 8 rests on a controllably liftable main stacking plate 10. The sheets 7 are removed from the top of the stack of sheets 8 by means of a suction head 18, which includes, among other things, a number of lifting and trailing suction cups for singulating the sheets 7. In addition, blowing devices are provided to loosen the upper layers of sheets for stack tracking. A number of lateral and rear stops 23, 24 are provided for aligning the stack of sheets 8, in particular the upper sheets 7 of the stack of sheets 8.

[0015] The feed table 9 is designed as a suction belt table and has at least one continuously rotating, air-permeable conveyor belt 26, which can be driven. A plurality of suction chambers 28, 29, 30 arranged one behind the other can be pressurized on the underside of its upper belt 27, which slides over the feed table 9 or conveyor table. The first suction chamber 28 is supplied with a constant high vacuum from a first suction source 31 to securely hold the sheets 7 separated from the sheet stack 8 by the suction head 18. The second suction chamber 29 is supplied with a constant low vacuum from a second suction source 32. In this area, the sheet stream lies on the feed table 9 in an overlapping pattern, thus completely covering it. Therefore, only a low vacuum is required to achieve sufficient holding force.The second suction chamber 29 also has a special design in which a pre-chamber 33 supplies a plurality of smaller suction chambers 34 arranged one behind the other in the direction of arc transport with suction air via at least one through-opening 36 each.

[0016] The third suction chamber 30 is located within one scale length s of the front marks 44 and is pressurized with a high vacuum by a third suction source 37. A rotary valve 38, located between the suction source 37 and the suction chamber 30, is driven in sync with the sheet processing machine and intermittently mixes ambient air with the high vacuum, thus switching the vacuum in the suction chamber 30 between a high and a low vacuum. This allows the first sheet 7.1 of the sheet stream to be laterally aligned by means of the provided alignment devices. During the lateral alignment of the first sheet 7.1, the sheet stream is conveyed further. This creates the problem that the contact area of ​​the second sheet 7.2 on the second suction chamber 29 decreases, resulting in an insufficient holding force acting on the second sheet.To remedy this problem, a fourth suction chamber 41 is provided upstream of the third suction chamber 30. The fourth suction chamber 41 is located within the second suction chamber 29 and has its own suction air connection. The fourth suction chamber 41 is supplied with suction air from the first suction source 31. The rotary valve 38 controls the vacuum level of the fourth suction chamber 41 by means of a second track 42, which is arranged out of phase with the first track 43 for controlling the third suction chamber 30, specifically by approximately 180°. This ensures that the third suction chamber 30 is supplied with high vacuum when the fourth suction chamber 41 is supplied with low vacuum, and vice versa. The tracks 42 and 43 are each designed to be approximately 200° long, so that they overlap by approximately 20° at the transition point.This measure ensures that after half a turn of the rotary valve, both suction chambers 30 and 41 are simultaneously supplied with a high vacuum.

[0017] The fourth suction chamber 41 is always supplied with high negative pressure when it is completely covered by a single arc. This prevents the air between arcs 7.1 and 7.2 from being sucked out by the high negative pressure.

[0018] In the exemplary embodiment, however, the fourth suction chamber 41 does not connect directly to the third suction chamber 30, but a small gap a remains in which a pressure level is generated under the conveyor belt 26 that corresponds to that of the second suction chamber 29. Since at least one of the two suction chambers 30 or 41 must be subjected to high suction force to achieve a sufficiently large holding force, the distance a and the length of the two suction chambers 30 and 41 in the sheet transport direction are less than one scale length s. The low negative pressure in the area a between the third suction chamber 30 and the fourth suction chamber 41 prevents an excessively high negative pressure from building up under the sheet in the area of ​​the suction chambers 30 and 41.

[0019] The Fig. Figures 3a to 3d show the flow of the arc stream during the feed to the arc processing machine 1.

[0020] In Fig. 3a The first arc 7.1 has covered the third suction chamber 30, while the subsequent arc 7.2 has not yet reached the fourth suction chamber 41. Suction chambers 30 and 41 are supplied with high negative pressure.

[0021] In Fig. 3b, the second arc 7.2 has reached the fourth suction chamber 41. At this point, the third suction chamber 30 is supplied with high negative pressure and the fourth suction chamber 41 with low negative pressure.

[0022] In Fig. 3c The first sheet 7.1 has not yet reached the designated front marks 44 for aligning the sheets in the sheet transport direction, while the second sheet 7.2 completely covers the fourth suction chamber 41 but has not yet reached the third suction chamber 30. The third suction chamber 30 and the fourth suction chamber 41 are subjected to high negative pressure at this time.

[0023] In Fig.In step 3d, the first arc 7.1 is aligned with the front marks 44, while the second arc 7.2 has reached the third suction chamber 30 and partially covers it. At this point, the third suction chamber 30 is supplied with low or no negative pressure, and the fourth suction chamber 41 with high negative pressure. Reference symbol list 1 printing press 2 investors 3 Printed matter 4 Printing work 5 . / . 6 outriggers 7 sheets 7.1 first arc 7.2 second bow 8 stacks of sheets 9 Feed table 10 stacking plates 11 plate cylinders 12 plate cylinders 13 . / . 14 . / . 15 . / . 16 . / . 17 . / . 18 suction heads 19 . / . 20 . / . 21 . / . 22 . / . 23 attacks 24 strikes 25 . / . 26 conveyor belt 27 Upper chord (26) 28 first suction chamber 29 second suction chamber 30 third suction chamber 31 first suction source 32 second suction source 33 Antechamber (29) 34 suction chambers (29) 35 . / . 36 Passage opening 37 third suction source 38 Rotary valve 39 . / . 40 . / . 41 fourth suction chamber 42 second lane (38) 43 first track (38) 44 Front mark a distance s scale length

Claims

[1] Device for conveying a shingled stream of sheets to a sheet processing machine, comprising a conveying table (9) which has at least one continuously driven, air-permeable conveyor belt (26) which can be subjected to negative pressure on an underside of its upper belt (26) sliding over the conveying table (9) by a first suction chamber (28), a second suction chamber (29) and a third suction chamber (30), wherein the third suction chamber (30) is the last suction chamber upstream of the sheet processing machine (1) and suction air of different pressure levels can be supplied to it in sync with the sheet processing machine (1), characterized by , that the third suction chamber (30) is preceded by a further suction chamber (41) to which suction air at different pressure levels can be supplied in sync with the sheet processing machine (1), that the third suction chamber (30) and the further suction chamber (41) can be subjected to high and low vacuum pressures in phase shifts by a common rotary valve (38), that the third suction chamber (30) and the further suction chamber (41) are arranged at a distance (a) from each other and that at the distance (a) a part of the second suction chamber (29) is arranged. [2] Device according to claim 1, characterized by , that the first suction chamber (28) has a constant high vacuum, the second suction chamber (29) has a constant low vacuum, the third suction chamber (30) has pulsed high and low vacuum and the further suction chamber (41) has pulsed low and high vacuum. [3] Device according to claim 1 or 2, characterized by , that the rotary valve (38) has a first track (43) for supplying the third suction chamber (30) and a second track (42) for supplying the further suction chamber (41). [4] Device according to claim 1, characterized by , that the phase shift is approximately 180°. [5] Device according to one of claims 1 to 4, characterized by , that the further suction chamber (41) is arranged to be supplied with suction air from a suction source (31) of the first suction chamber (28). [6] Device according to any one of the preceding claims, characterized by , that the distance (a) and a length of the third suction chamber (30) and a length of the further suction chamber (41) seen in the arc transport direction is smaller than a scale length (s).

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