Mechanism for laterally aligning sheets

Abstract

The invention relates to a mechanism for laterally aligning sheets, said mechanism comprising a suction device that grips the sheets and guides them with the side edges against a side lay. The mechanism comprises at least one suction plate provided with suction holes. The invention modifies a mechanism for laterally aligning sheets in such a way that heavy and special print substrates can be gripped and aligned easily by the side edges. The mechanism of the present invention comprises suction openings (8.1) of the suction holes (8) open into grooves (9), which are open towards the sheets to be aligned (FIG. 1).

Description

FIELD OF THE INVENTION

[0001] The invention relates to a mechanism for laterally aligning sheets, said mechanism comprising a suction device, which grips the sheets and guides them with the side edges thereof against a side lay and which comprises at least one suction plate provided with suction holes.

BACKGROUND OF THE INVENTION

[0002] Mechanisms for laterally aligning the sheets that are usually fed in a continuous stream operation to a printing machine are generally known, and are arranged in the feed table in such a way that the suction device is flush with the surface of the feed table. The suction device comprises at least one suction plate provided with suction holes, wherein the suction holes open into the surface of the suction plate. The suction holes are supplied cyclically with suction air, to which every sheet located over the suction device is sucked, the suction device being displaced transversely to the sheet conveying direction by a drive so that the sheet is guided with its side edge against a side lay and thus aligned by its side edge.

[0003] When processing heavy or special print substrates, such as unilaterally covered corrugated cardboard carton, it is necessary for the suction device to realize a high retention force. This is achieved in DE 44 15 494 C2 by providing a sucker next to the suction plate, said sucker being provided on its side facing the sheet with depressions and grooves, which are provided with suction air via a central hole. In addition, an annular gap is provided between the outer periphery of the sucker and the suction device, said annular gap also being supplied with low pressure for increasing the retention force in the case of heavy print substrates. In spite of this measure, it is not possible for the suction device to grip the entire pallet of the heavy or special print substrates arriving for processing and to align them reliably in relation to the side edge. It is therefore necessary to provide a push lay for this purpose and to mount it if required. This leads to additional expenses and also a format limitation.

SUMMARY OF THE INVENTION

[0004] It is the object of the invention to modify a mechanism for laterally aligning sheets in such a way that heavy and special print substrates can be gripped and aligned easily by the side edges.

[0005] Said object is attained according to the invention by a mechanism in accordance with the characteristics specified in Claim 1.

[0006] The solution according to the invention permits even heavy print substrates or print substrates, which due to their design cannot be gripped reliably by the suction device guiding the sheet against the side lay, to be aligned easily by the side edges. In doing so, the mechanism is realized without any format limitation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows.

[0008] FIG. 1, is a schematic representation of a suction device,

[0009] FIG. 2, illustrates a section along the line A-A shown in FIG. 1,

[0010] FIG. 3, illustrates a section along the line B-B shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 illustrates a suction device (1) that comprises a suction plate (2) and e.g., a double sucker (3). The suction device (1) is arranged on a suction pulling rail (4) that is moved transversely in a sheet conveying direction (5) in the machine cycle, towards a fixedly arranged side lay (6) and which is guided back by the latter. For this purpose, the suction pulling rail (4) is mounted displaceably in a feed table (7) with the surface of the feed table (7) flushed with the surface of the suction pulling rail (4). In the suction plate (2), suction holes (8) are provided, which are supplied with low pressure using a suction box (not illustrated) connected to a vacuum system. The suction holes (8) are provided with suction openings (8.1), which open into the base (9.1) of grooves (9). The grooves (9) are arranged in the suction pulling rail (4) or in the suction plate (2) and are open towards the sheet to be aligned. The grooves (9) can be arranged in any position on the suction plate (2). That is, as illustrated in FIG. 1, they can be arranged in the suction plate (2) transversely to the sheet conveying direction (5), or parallel or at an inclination thereto. If the grooves (9) are arranged transversely to the sheet conveying direction (5) or at a slight inclination thereto, it is advantageous to prevent the conveyed sheets from getting stuck by designing the groove walls (10) located at the front in the sheet conveying direction (5) in such a way that they are inclined towards the sheet conveying direction (5). An angle, .alpha., of approximately 60.degree. has proved to be advantageous for this purpose.

[0012] The sheets are conveyed in a continuous stream operation from a belt table towards the feed table (7) in the known manner and the respective foremost sheet of the stream of sheets is transported with its leading edge against front lays positioned on the feed table (7) and thus aligned by its leading edge. Thereafter, if double suckers (3) are arranged in the suction pulling rail (4) as in the exemplary embodiment, said double suckers (3) and the suction holes (8) of the suction plate (2) are activated by supplying them with low pressure. By arranging the suction openings (8.1) in the base (9.1) of the grooves (9) open towards the sheet to be aligned, instead of arranging them on the surface of the suction plate (2), the effective suction surface of the suction plate (2) is increased. Furthermore, it has been observed that the corrugation in unilaterally covered corrugated cardboard cartons, or the material in heavy print substrates is not merely pulled against the suction plate (2) after low pressure is supplied to the grooves (9). Instead, it undergoes slight deformation elastically so as to fit the contour of the grooves (9). A more or less form fit between the sheet to be aligned and also the grooves (9) of the suction plate (2) is thus realized and a high pulling force is made possible. As a result, heavy or special print substrates are gripped reliably and likewise guided with the side edge against the side lay (6).

[0013] Subsequently, the suction air supply to the double sucker (3) and also to the suction plate (2) is interrupted in the known manner and the sheet aligned by the leading edge and side edge thereof is conveyed into the machine arranged downstream.

[0014] Since the suction pulling rail (4) with grooves (9) that are open towards the sheet to be aligned is not suitable for aligning arbitrary print substrates, said suction pulling rail can be replaced. For this purpose, holes (11) are provided in the suction pulling rail (4) so as to be able to connect the suction pulling rail (4) to a slide, which can be mounted in the feed table (7) and displaced transversely to the sheet conveying direction (5) in the work cycle. It is also possible to design only the suction plate (2) to be replaceable and to replace it whenever required.

LIST OF REFERENCE NUMERALS USED

[0015] 1 Suction device [0016] 2 Suction plate [0017] 3 Double sucker [0018] 4 Suction pulling rail [0019] 5 Sheet conveying direction [0020] 6 Side lay [0021] 7 Feed table [0022] 8 Suction hole [0023] 8.1 Suction opening [0024] 9 Groove [0025] 9.1 Groove base [0026] 10 Groove wall [0027] 11 Hole [0028] .alpha. Angle

Claims

1. A mechanism for laterally aligning sheets, said mechanism comprising a suction device, which grips the sheets of paper and guides them with the side edges thereof against a side lay and which comprises at least one suction plate provided with suction holes, said mechanism being characterized in that suction openings (8.1) of the suction holes (8) open out into grooves (9), which are open towards the sheets to be aligned.

2. The mechanism of claim 1, wherein said suction openings (8.1) are arranged in the base (9.1) of said grooves (9).

3. The mechanism of claim 1, wherein said grooves (9) are arranged transversely to said sheet conveying direction (5).

4. The mechanism of claim 1, wherein said grooves (9) are arranged parallel to said sheet conveying direction (5).

5. The mechanism of claim 1, wherein said grooves (9) are arranged such that they are inclined towards said sheet conveying direction (5).

6. The mechanism of claim 1, wherein said suction plate (2) is accommodated in said suction pulling rail (4).

7. The mechanism of claim 6, wherein said suction plate (2) is designed to be replaceable.

8. The mechanism of claim 6, wherein said suction pulling rail (4) is designed to be replaceable.