EP0006522B1 - Method of and apparatus for opening folded printed sheets - Google Patents

Description

The invention relates to a method and a device for opening folded printed sheets, in particular for placing them on the conveyor saddle of a book stitching machine, in which an openable sheet is held by a conveying device on successive pneumatic devices for spreading out the individual, individual sheet parts one after the other up to an opening point is guided past in the printing sheet by grasping the printing sheet parts at a point opposite the back of the printing sheet, lifting them off the remaining printing sheet and directing them from the effective area of a downstream device for spreading in order to detect a subsequent printing sheet part.

DE-C-581077 discloses a method and a device for opening folded printed sheets, in which folded printed sheets with a horizontally lying, upwardly directed folded edge are occasionally transferred from a magazine to a conveying device and are guided past suction devices arranged one behind the other. The individual sheet parts are spread apart one after the other up to the middle of the sheet from the rest of the sheet by suction devices capturing the respective outer sheet parts at a point opposite the sheet back and deflecting means keeping the spread sheet parts out of the effective range of the downstream suction device. Ultimately, the printed sheet opened in this way is transported to the saddle of a downstream processing machine.

The method and device of this known type are severely restricted in their field of application, insofar as, owing to the position of the printed sheets with the fold edge lying horizontally, not every type of printed sheet can be opened in the center. For example, printed sheets with cross fold folding, that is printed sheets that are partially closed at the foot or head, cannot be transported over the suction device and consequently cannot be processed.

Some printed sheets folded in the cross fold allow the suction device to lead them in the opposite direction, but this is only possible with a corresponding contact edge in the downstream processing machine, which, depending on the manufacturer, can be at the front and back when viewed in the direction of travel.

In the opening device according to the patent specification DE-C-581077, the printed sheets are transported one after the other and at a distance from one another past the suction and deflection devices, consequently the opening process at an opening station must always be ended before a subsequent printed sheet can run in. As a result, the device is limited in terms of an increase in the number of cycles, especially since, due to the so-called suction plate effect between two press sheet parts, a certain time is always required for the air to enter and thus to detach the foremost press sheet part, one wants to prevent the following press sheet part from being carried away.

In addition, the suction nozzles used in this known device are also not able to reliably detect all types of paper. For example, in the case of printed sheets consisting of strongly porous paper or printed sheets with inserted printed sheet parts from this strongly porous paper, trouble-free opening as a result of the suction effect can often not be achieved.

DE-A-2362125 describes a device for separating sheets from a stack of sheets or for separating two sheets and for advancing using a fluid flow generating a vacuum between a convex surface and a sheet to be handled. In this separating device, which works according to the wall jet effect, the flow emerging from the nozzle always remains on the curved surface, so that due to the centrifugal forces which arise here, only a slight suction effect is exerted on the sheet to be separated without any remote action. Papers with a relatively high degree of stiffness, such as those used in printed sheets, cannot be lifted over a greater distance without additional mechanical movement of the separating elements, since contact with the nozzle occurs only at the nozzle exit surface. Only small bending moments act on the blade and consequently the leverage required to spread out curved parts with a higher degree of inherent rigidity is not available.

The object on which the invention is based is to create a method and a device of the type mentioned at the outset which enable reliable opening of all printed sheets and types of paper and with which a substantial increase in the number of cycles is achieved.

The method according to the invention first provides that the printing sheets are transported in a conveyor device with a printing sheet corner ahead and the opening at the corner adjacent to the preceding printing sheet corner is carried out by means of blowing air suction devices, in that the individual printing sheet parts are spread apart by the suction effect of the blowing air.

In a preferred embodiment of the method, the printed sheets can be transported in a scale-like manner past the blowing air suction devices and the printed sheet parts can be spread apart by approximately 15 °.

The device for carrying out the method is based on a printing sheet feeder for separating printed sheets and a conveying device for holding and conveying the printed sheets past pneumatic devices arranged one behind the other for spreading out the individual printed sheet parts one after the other Opening point in the printed sheet, the printed sheet parts being lifted from the rest of the printed sheet at a point opposite the printed sheet back by the pneumatic devices and immediately downstream of the pneumatic devices, the spread sheet part leading out of the effective range of a subsequent pneumatic device is provided for sheet deflectors. The device is characterized by a printing sheet feeder feeding the printing sheets of a conveying device with a printing sheet corner ahead and by blowing air suction plates acting on the corner adjacent to the preceding printing sheet corner with suction surfaces inclined at a flat angle to the sheet transport plane, in which blowing air nozzles producing a suction effect are arranged. _{- -} _ _ _-

The invention shows for the first time a way by which the processing of all types of printing sheets is made possible, since only the corner of the printing sheet is opened and the nature of the rear printing sheet edge is of no importance. Sufficient time is available for safely lifting the sheet corner to lift off the outer sheet parts.

The use of the blowing air suction effect for. Opening folded printed sheets ensures reliable opening of all types of paper. Since the suction effect on the sheet to be opened is always only as great as the reset voltage, the suction force reduced compared to the suction force cannot hold the sheet behind it with the same reset voltage. As a result, only the outermost part of the printed sheet is detected and double deduction with porous paper is reliably prevented.

In addition, the invention permits an increase in the number of cycles, particularly in connection with the scale formation according to claim 2.

Due to the relatively high restoring forces of the paper, caused by the opening at the printing sheet corners, the adhesive effect between two printing sheet parts and thus a simultaneous lifting of two printing sheet parts can also be excluded, which also favors the functional reliability.

In order to achieve an optimal blowing air suction effect, the blowing air nozzles emerge from the blowing air suction plates at an angle of approximately 15 ° in an advantageous embodiment and the blowing air nozzles are directed against the direction of the printing sheet to the spreading sheet corner.

It is also advantageous if the blowing air nozzles are arranged in a line that rises in the direction opposite to the direction of the printing sheet, which enables the outer part of the printing sheet to be gradually drawn up to its corner, starting with the first nozzle closest to the printing sheet the result that the opening device manages with a minimum of blowing air.

Another feature provides that the blow air nozzles have a depression on the outlet side. This avoids jet deflection, as occurs in nozzles with an inclined section.

According to a last feature of the invention, the blowing air suction plates are wedge-shaped in the direction of the printed sheet back and the printed sheet deflecting means are formed in each case by the rear side of a downstream blowing air suction plate and by a dividing tip arranged in front of the latter. The wedge shape of the air suction plates is advantageous in that it prevents the bend parts from kinking and thus prevents them from being deformed when they are spread out. A construction which is inexpensive in terms of production and assembly is based on the fact that the blower air suction plate and sheet deflection means are designed as one component.

• Fig. 1 eine perspektivische Teildarstellung der Vorrichtung zum Öffnen gefalzter Druckbogen,
• Fig. 2 eine Seitenansicht der Vorrichtung in einer verkleinerten Darstellung,
• Fig. 3 eine vergrösserte Schnittdarstellung durch eine erfindungsgemässe Blasluft-Saugeinrichtung gemäss der Schnittlinie A-B in Fig. 2.

An embodiment of an apparatus for performing the method according to the invention is shown schematically in the drawing. It shows:

• 1 is a partial perspective view of the device for opening folded printed sheets,
• 2 is a side view of the device in a reduced view,
• 3 is an enlarged sectional view through a blown air suction device according to the invention along the section line AB in FIG. 2.

The device for opening folded printed sheets 1 essentially consists of a conveying device 2 and a plurality of blown air suction devices 3 located one behind the other along the movement path of the printed sheets.

Via a known drum feeder 4 arranged obliquely in front of the conveying device and therefore not described in detail, the closed printing sheets 1 are transferred endlessly, the printing sheets between clamping conveyor belts and are transported with their backs up and with a printing sheet corner ahead of the blown air suction devices.

It has proven to be advantageous to run the printed sheets in the form of scales in order to significantly increase the number of cycles. In addition, this diagonal transport enables processing of all types of folding sheets, since the printing sheets are opened via a sheet corner and the nature of the rear sheet edge is of no importance.

As particularly clearly illustrated in FIG. 3, the devices for opening the printing sheets consist of wedge-shaped blowing air suction plates installed on the side of the plane of movement of the printing sheets 1 on a supporting part 8, with a suction surface 5 directed towards the opening of the printing sheet and inclined at approximately 15 ° with a Row of blowing air nozzles 6, which are connected to a compressed air source, not shown.

When passing the blowing air suction plates, the outer part of the layer is caused by the so-called called hydrodynamic paradoxes sucked onto surface 5 and redirected by about 15 °.

In order to bring a next printed sheet part into the effective area of the blown air of a subsequent suction plate, the first printed sheet part spread apart from the remaining layer is placed behind the subsequent blown air suction plate, i.e. directed to its back 5 '. For this purpose, in front of the suction plates, with the exception of the foremost ones, there are deflection devices in the form of divider tips 7 arranged in front of the suction plates.

The blown air suction effect used ensures that all types of paper can be opened reliably. Since the suction effect on the sheet to be opened is always only as great as the reset voltage, the suction force reduced compared to the suction force cannot hold the sheet behind it with the same reset voltage. As a result, only the outermost part of the printed sheet is detected and double deduction with porous paper is reliably prevented.

Since the opening is carried out at the corners of the printing sheet, the adhesive effect between two printing sheet parts and thus a simultaneous lifting of two printing sheet parts can also be excluded due to the relatively high restoring forces of the paper. This and, not least, the special sheet transport, which provides enough time to safely grasp the sheet corner, further increases functional reliability.

The position of the nozzle bores 6 in the suction plates was indicated in FIG. 1 by the dashed arrows representing the air outlet. The nozzle bores are directed counter to the direction of travel of the printed sheets toward the opening of the printed sheets and are arranged at an angle of 15 ° to the suction surface 5, as shown in FIG. 3, which is useful for an optimal blowing-suction effect.

In addition, the nozzle bores 6 are still in a line that rises in the direction opposite to the running direction, which enables a gradual pulling up of the respective outer part of the printing sheet to its corner, starting at the first nozzle closest to the printing sheet. As a result, the opening device can make do with a minimum of blown air.

In order to prevent the jet deflection occurring in the case of nozzles with an inclined section and to prevent the formation of eddies which occurred in the process, the nozzle bores were additionally equipped with bores 6 '.

In order to process different printed sheet formats, the conveying device can be designed to be height-adjustable in a manner known per se and therefore not described in relation to the feeder.

If a folded printed sheet, which is to be understood as any type of position, is to be placed astride a support saddle 11 of a book sewing machine, for example, the initially closed printed sheet is transported by the conveying device 2 past a first blowing air suction device and a first outer sheet part through it Blow-suction effect at its opening corner spread apart from the rest of the printed sheet and steered behind it by means of the divider tip of a subsequent blow-air suction device. As a result, a second, again external, printed sheet part reaches the effective area of the following blowing air suction device in order to be spread apart by it and deflected by a following blowing air suction device.

The individual printed sheet parts are thus successively opened up to the opening point in the printed sheet in order to ultimately be transferred to a saddle.

The present invention is not limited to the preferred exemplary embodiment shown and described. Without leaving the field of the invention, the blowing air suction plates can also be arranged parallel to the printing sheet conveying plane and can be swiveled away after detection of a printing sheet part. A construction is also conceivable, which provides blowing air suction devices on both sides of the conveying device, as a result of which sheet parts are spread apart on both sides at the same time.

Claims (8)

1. Procedure to open folded printed sheets (1), in particular for placing them on the conveyor saddle (11) of a thread stitching machine for books, in the course of which a printed sheet (1) to be opened is seized by a conveyor (2) and carried past successively arranged pneumatic devices (3) for the individual printed sheet parts to be one after the other spread apart up to an opening point in the printed sheet (1) with the printed sheet parts being seized at a point opposite the back of the printed sheet, lifted off the remaing printed sheet and carried out of the sphere of action of a subsequent spreading device thus permitting the next following printed sheet part to be seized, characterized by the fact that the printed sheets (1) are transported with a printed sheet corner first in a conveyor (2) and that the opening takes place at the corner adjacent to the leading printed sheet corner by means of forced air suction devices (3) with the individual printed sheet parts being spread apart by the suction effect of the forced air.

2. Procedure as per claim 1, characterized by the fact that the printed sheets (1) are transported past the forced air suction devices (3) in an imbricated formation.

3. Procedure as per claim 1 or 2, characterized by the fact that the printed sheet parts are spread apart by about 15°.

4. Device to carry out the procedure as per claim 1 with a printed sheet feeder (4) to single out the printed sheets (1) and with a conveyor (2) to hold and convey the printed sheets (1) past successively arranged pneumatic devices (3) to spread the individual printed sheet parts apart one after the other up to an opening point in the printed sheet (1) with the printed sheet parts being lifted off the remaining printed sheet by the pneumatic devices (3) and fed to sheet deflectors (5', 7) leading the spread-apart sheet part out of the sphere of action of a following pneumatic device installed immediately behind the pneumatic devices (3), characterized by a printed sheet feeder (4) feeding the printed sheets (1) with a printed sheet corner first to a conveyor (3) and by forced air suction plates (3) acting upon the corner adjacent to the leading printed sheet corner with suction surfaces (5) inclined at a flat angle in relation to the sheet transport plane, said suction surfaces (5) housing the forces air nozzles (6) producing a suction effect.

5. Device as per claim 4, characterized by the fact that the forced air nozzles (6) protrude from the forced air suction plates (3) at an angle of about 15° and that the forced air nozzles (6) are directed towards the printed sheet corner to be spread apart contrary to the moving direction of the printed sheets.

6. Device as per claim 4 or 5, characterized by the fact that the forced air nozzles (6) are arranged in an ascending line contrary to the moving direction of the printed sheets.

7. Device as per one of the claims 4 to 6, characterized by the fact that the forces air nozzles (6) have an inclination (6') on the outlet side.

8. Device as per one of the claims 4 to 7, characterized by the fact that the forced air suction plates (3) are of a wedge-sheped design towards the back of the printed sheet and that the printed sheet deflectors are always formed by the rear side (5') of a subsequent forced air suction plate (3) as well as by a divider point (7) situated in front of the same.

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