EP2098469B1 - Method for measuring the position of sheets and aligning sheets - Google Patents

Description

The invention relates to methods for measuring the position of sheets in a printing press or print finishing machine according to the preamble of claim 1 and method for aligning sheets in a printing or printing finishing machine according to the preamble of claims 4 and 6.

State of the art

As punching the cutting is referred to with closed geometric blank forms that can be circular, oval or polygonal and imaginary shapes of all kinds. Also the practices practiced in print finishing, such as punching with punch, corner punching and register punching are counted to this area. The punching takes place against a punching pad or against stamp, in some cases it is also shearing operations. Packaging materials made of paper, cardboard, cardboard or corrugated board are mainly punched in sheet format. When punching but also creasing lines or blind embossing can be introduced into the benefit. This complex process makes it indispensable to punch the sheets individually. Since the end products are sophisticated packaging in terms of technical and graphic design (such as packaging for cosmetics, cigarettes, pharmacy, food, etc.), special requirements are not only placed on the packaging materials themselves, but are also punching tools for optimum results required with the smallest tolerances and extremely precise and reliable punching machines. Flatbed punching best meets these demands. The printed sheets stacked on a pallet are fed to the punching machine. In the machine, the sheets to be punched are precisely aligned in an alignment device, taken over by a gripper carriage and positioned exactly in the punching device between a fixed undercounter and a vertical over a knee lever or eccentric upper table.

In known sheet punching and embossing machines, which are used for punching, breaking, embossing and depositing sheets of paper, cardboard and the same, it is known move the sheets by means of gripper carriage through the individual stations of the machine. Grippers are attached to the gripper carriage, gripping the arches at a front end, the gripper carriages themselves being moved through the machine on endless chains. This type of movement of the sheets through the machine enables continuous operation in the individual successively arranged stations of the machine.

Such a flat bed punch is for example from the DE 30 44 083 A1 known. The two tables are equipped with cutting and scoring tools or corresponding counter tools with which punched out of the cyclically guided between the table surface sheets the benefits and at the same time pressed the necessary for clean folding grooves. In the subsequent breakout the waste is removed by machine tools. Depending on the equipment of the machine finally the punched benefits can be separated in a designated Nutzentrenneinrichtung.

In order to achieve a high product quality of the punched sheets, it is necessary that the sheets and tools are precisely aligned with each other. In the punching station of a sheet punching and embossing machine, the punching tool and punched riddle plate must be brought to an exact position in the circumferential direction. It must also be ensured that both tools are directly perpendicular to the sheet transport direction without skewing. This reference position is called "first knife". In the subsequent processing stations, the tools must be adjusted relative to the position of the first knife, such. B. the stripping board in the breaker and the Nutzentrenngitter in the Nutzentrennstation. The tools must be set in their three degrees of freedom. During operation of the sheet punching and embossing machine, it may be necessary to readjust the position of the tools in the punching station. The tools in the subsequent processing stations must also be readjusted to bring them back into the correct position relative to the "first knife".

This elaborate adjustment work of the tools ensures that the sheets are processed accurately. The register describes the positional accuracy of the Print image of the cutting, creasing and breaking edges of the sheet. A distinction is made between circumferential alignment, ie the positional accuracy in the machine direction and side registration, ie the positional accuracy transverse to the machine direction.

A disadvantage of the register-accurate alignment of the prior art is that due to the high set-up times, i. due to the high time required for the adjustment of the tools, the machine productivity is impaired.

• Die DE OS 25 20 232 beschreibt eine Vorrichtung zur Übergabe von Bogen an eine Bogenverarbeitende Maschine. Dabei werden im Bereich eines Zuführtischs eine auf den Bogen aufgedruckte Marke, eine sogenannte Druckmarke, oder eine Seitenkante des Bogens durch Sensoren erfasst und der Zuführtisch wird quer zur Bogentransportrichtung so verschoben, dass der Bogen in seiner richtigen, seitenausgerichteten Lage an das Bogentransportsystem der Bogenverarbeitenden Maschine übergeben werden kann.

From the prior art various measuring devices are known, which are preceded by the accurate register alignment of a sheet:

• The DE OS 25 20 232 describes a device for transferring sheets to a sheet processing machine. In this case, in the area of a feed table, a mark printed on the sheet, a so-called print mark, or a side edge of the sheet is detected by sensors and the feed table is moved transversely to the sheet transport direction so that the sheet in its correct, side-facing position to the sheet transport system of the sheet processing machine can be handed over.

The DE 693 14 155 T2 describes a method for monitoring moving web material, wherein the edges of the web are detected by sensors.

The DE 202 16 042 U1 shows a device for detecting the edges of sheets in sheet-processing machines. The device comprises a line sensor, which is connected to an evaluation unit, and in which the sheet position is calculated from the signal of the sensor.

Also from the DE 101 36 870 A1 A device for detecting the position of an edge of a sheet in a printing machine emerges. In the feeder table of the printing press, a scanner line is embedded, this scanner line being associated with a reflector located above the feeder table. Similar facilities also go out of the DE 101 36 871 A1 , of the DE 101 36 872 A1 , of the DE 101 36 873 A1 , of the DE 101 36 874 A1 , of the EP 1 300 353 A2 and the EP 1 300 354 A2 out.

The DE 39 16 405 A1 discloses an apparatus for aligning sheets, wherein a camera is provided above the corners of a sheet so that front and side edges can be read out simultaneously. Depending on the measurement result, motors are activated to adjust the front and side stops.

The document also discloses a method for measuring the position of a sheet of paper, paperboard and the like in an outermost plane in the feeder of a postpress processing machine having at least one optical sensor in the form of a camera, the sheet having at least one printed mark. This method comprises the steps of: entering the nominal distance between the sheet edge and the mark in the control unit of the sensor; Determination of the measuring field to be detected by the sensor by the operator; subsequent monitoring of the measuring field by the sensor; Determining the position of the mark and thus the position of the arc through the sensor. Further disclosed DE 39 16 405 A1 in that an alignment of the lateral position is carried out on the basis of the specific position of the sheet and that the alignment plane on which the sheet is measured has black zones in the region of the sensor around a German contrast between these zones and the edges of the sheet relative to the sensor or to achieve a camera.

The object of the present invention is to provide methods for measuring the position of a sheet in a printing or printing finishing machine, which allow a subsequent accurate alignment of the sheet.

This object is achieved by a method having the characterizing features of claim 1.

The invention relates to a method for measuring the position of a sheet of paper, cardboard and the like in an alignment plane in the feeder of a printing or printing finishing machine. The print finishing machine can in particular be a sheet punching and / or embossing machine. The sheet to be measured can, for. B. by front lays and side pull marks, already be mechanically anticipated. During the measurement, the arc is at rest, which allows an accurate measurement. The machine control of the print or print finishing machine initiates the measurement once the sheet is at rest. In the area of the alignment level in the feeder, the print or print finishing machine has at least one optical sensor. This can be embodied as an autocollimation system in which the transmitter and receiver lie on an optical axis and white light LEDs serve as transmitters. The printing or printing finishing machine may advantageously also have a plurality of sensors. The alignment plane has a highly reflective surface at least in the region of the at least one sensor. This can be formed for example by a reflective foil.
The sheet to be measured may have a printed mark. Under a printed mark is a line-shaped contrast to understand, ie a line as the boundary between two gray levels, which can be seen on the printed sheet. This contrast can be part of the printed image, z. As the edge of the printed image, or printed as a separate item. Between the sheet edge and the mark, the bow should have a homogeneous color, ie there should be a clear contrast.
The method according to the invention comprises the following steps:

In a first step, it is determined whether the sheet has a printed mark. If the sheet has a printed mark, in a second step, the nominal distance between sheet edge and mark is entered into the control unit of the sensor. This input can also be done by the machine control of the print or print finishing machine. The nominal distance between the sheet edge and the mark is known and results from the print image data.
If the sheet has several marks, the respective distances are entered into the control unit. In any case, however, the determination of the to be monitored by a respective sensor measuring field. If a plurality of sensors are used, it is advantageous for one sensor each to be assigned to one brand. If the sheet is already mechanically pre-aligned in the alignment plane, then the position of the sheet edge is predetermined and known during the measurement by the mechanical pre-alignment. The measurement field is thus determined by the tolerance of the position of the sheet edge and the tolerance of the position of the mark. Thus, only a small area must be evaluated by the sensor, advantageously a square with an edge length of a maximum of 1.5 mm, whereby the evaluation time and the computational effort can be minimized and the accuracy can be increased. If the sheet is not mechanically aligned in the alignment plane, the sensor must detect a larger measuring field.

In a third step, the monitoring of the measuring field in which the mark or the sheet edge is located takes place. This is done using known algorithms, in particular also to perform extraneous light compensation. If the sheet has no marks, for example, three sensors are present, it can be monitored by two sensors, the sheet leading edge and by a sensor a sheet side edge. There is an increase in contrast. With increasing contrast, the measurement accuracy can be increased. Contrast means a difference in the reflected light intensity.

In a fourth step, the position of the mark or the position of the sheet edge is determined by the sensor and thereby determines the position of the sheet. In determining the location of the mark, the data provided by the sensor can be mathematically approximated by a polynomial or spline to compensate for stochastic effects.

If several sensors and several brands are present and a sensor is assigned a respective mark, the position of a mark is determined in each case by a sensor and the position of the sheet is determined from the data provided by all the sensors.

In an advantageous development of the aforementioned method, the orientation of the sheet is based on the results of the measurement in a subsequent step. The combination of mechanical and optosensory method for sheet alignment allows advantageously a very precise alignment of the sheet.

The invention also provides a method for the page orientation of a sheet of paper, cardboard, plastic or the like in an alignment plane in the feeder of a printing or printing finishing machine. The printing or postpress machine has at least one optical sensor and means for aligning the sheet with an actuator. The sheet may have one or more stamps printed on it. In a first step, the determination of the desired difference distance between the print mark and zero point of the sensor when the sheet has a print mark, or between edge of the sheet and zero point of the sensor, if the sheet has no print mark. This desired difference distance is entered into the machine control of the printing or printing finishing machine. The determination takes place once at the beginning of each order.
In a second step, the position of the sheet is determined by the method described above. The method can be automatically selected by the machine control or can be entered by the machine operator in this. The sensor can be controlled accordingly via a PLC multi-function input, for example.
In a third step, the determination of an actual difference distance transversely to the sheet transport direction between the print mark and the zero point of the sensor or between the edge of the sheet and the zero point of the sensor.
In a fourth step, the determined value of the actual difference distance is transferred to the machine control.
By the machine control, the difference between the actual difference distance and the desired difference distance is determined in a fifth step and the actuator for the page orientation of the sheet is controlled accordingly.
Steps two through five repeat for the page orientation of each sheet.

The invention further comprises a method for setting up a device for page orientation of sheets of paper, cardboard, plastic or the like in an alignment plane in the feeder of a sheet punching and / or embossing machine. The sheet punching and / or embossing machine has at least one optical sensor and an actuator for the page orientation of the sheet. Following the steps performed within the page orientation procedure, at least one sheet is punched. At the punched sheet, a comparison of the deviation between the printed image and stamped image. Corresponding to the deviations determined, the zero point of the at least one sensor is corrected. This is preferably done by a displacement of the sensor, which can be done manually or by motor.

• In einem ersten Schritt erfolgt einmalig eine Ermittlung der Soll-Differenzstrecke zwischen Druckmarke und Nullpunkt des zugeordneten Sensors bzw. zwischen Kante des Bogens und Nullpunkt des zugeordneten Sensors. Diese jeweilige Soll-Differenzstrecke wird in die Maschinensteuerung der Druck- oder Druckweiterverarbeitungsmaschine eingegeben.
• In einem zweiten Schritt erfolgt vorteilhafterweise eine mechanische Vorausrichtung des Bogens durch Vordermarken.
• In einem dritten Schritt erfolgt die Bestimmung der Lage des Bogens mit dem oben beschriebenen erfindungsgemäßen Verfahren.
• In einem vierten Schritt erfolgt die Bestimmung einer jeweiligen Differenzstrecke in Bogentransportrichtung zwischen Druckmarke und Nullpunkt des Sensors bzw. zwischen Kante des Bogens und Nullpunkt des Sensors.
• In einem fünften Schritt wird der ermittelte Wert der Differenzstrecke bzw. der Differenzstrecken an die Maschinensteuerung übergeben.
• In einem sechsten Schritt wird der Unterschied zwischen jeweiliger Ist-Differenzstrecke und Soll-Differenzstrecke ermittelt und ein bogenindividueller Korrekturwert berechnet.
• In einem letzten Schritt wird der Linearantrieb durch die Maschinensteuerung unter Berücksichtigung von bogenindividuellen Korrekturwerten angesteuert. Dabei gibt es für den antriebseitigen Linearantrieb und den bedienerseitigen Linearantrieb der Druck- oder Druckweiterverarbeitungsmaschine jeweils einen eigenen Korrekturwert.

The invention further includes a method of circumferentially aligning a sheet of paper, paperboard, plastic or the like in a printing or post-processing machine. The printing or printing finishing machine has a transport system for transporting the sheets through the machine, the transport system comprising gripper carriages with grippers for gripping the sheets, the gripper carriages being driven by electric linear drives with alternating field motors. From the DE 20 2007 012 347 U1 is a sheet punching machine with such a transport system known. In the region of the alignment plane of an investor of the printing or printing finishing machine, this has at least one optical sensor. The sheets to be aligned may have one or more stamps printed on them. The circumferential alignment comprises the following steps:

• In a first step, a determination of the desired difference distance between the print mark and the zero point of the associated sensor or between the edge of the sheet and the zero point of the associated sensor takes place once. This respective desired difference distance is entered into the machine control of the printing or printing finishing machine.
• In a second step advantageously takes place a mechanical pre-alignment of the sheet by front marks.
• In a third step, the determination of the position of the sheet with the above-described inventive method.
• In a fourth step, the determination of a respective difference distance in the sheet transport direction between print mark and zero point of the sensor or between edge of the sheet and zero point of the sensor.
• In a fifth step, the determined value of the difference distance or the difference distances is transferred to the machine control.
• In a sixth step, the difference between the respective actual difference distance and the desired difference distance is determined and a correction value calculated for each individual arc is calculated.
• In a final step, the linear drive is controlled by the machine control, taking account of arc-specific correction values. In each case, there is a separate correction value for the drive-side linear drive and the operator-side linear drive of the printing or printing finishing machine.

With regard to further advantageous embodiments of the invention, reference is made to the dependent claims and the description of an embodiment with reference to the accompanying drawings.

embodiment

Fig. 1

eine Bogenstanzmaschine

Fig. 2a

den Bereich des Anlegers im Detail

Fig. 2b

eine Draufsicht auf einen auf dem Zuführtisch liegenden Bogen

Fig. 3

eine Prinzipskizze der Bogenstanze mit Transportsystem mit Linearantrieb

The invention will be explained in more detail with reference to an embodiment. It show in a schematic representation

Fig. 1

a sheet punching machine

Fig. 2a

the area of the investor in detail

Fig. 2b

a plan view of lying on the feed sheet

Fig. 3

a schematic diagram of the sheet punching machine with transport system with linear drive

In FIG. 1 the basic structure of a sheet punching and embossing machine 100 for punching, breaking and depositing sheets of paper, cardboard and the like is shown. The punching and embossing machine 100 has a feeder 1, a punching station 2, a breaking station 3 and a boom 4, which are supported and enclosed by a common machine housing 5.

The sheets 6 are separated by a feeder 1 from a stack and supplied and attached to gripper bars of gripper carriage 8 grippers at its front edge taken and in the sheet transport direction F intermittently pulled through the various stations 2, 3 and 4 of the punching and embossing machine 100.

In the area of the feed table 16 between feeder 1 and punching station 2 there is a measuring system 20 for precise measurement of the position of the sheets 6.

The punching station 2 consists of a lower table 9 and an upper table 10. The lower table 9 is fixedly mounted in the machine frame and provided with a counter plate to the punching knife. The upper table 10 is supported vertically movable back and forth.

The gripper carriage 8 transports the sheet 6 from the punching and embossing station 2 in the subsequent breaking station 3, which is equipped with breakout tools. In the breaking station 3, the unwanted pieces of waste are pushed out of the sheet 6 downwards with the aid of the stripping tools, whereby the waste pieces 11 fall into a container-like carriage 12 inserted below the station.

From the stripping station 3, the sheet enters the boom 4, where the sheet is either simply stored, or at the same time there is a separation of the individual benefits. The boom 4 may also include a pallet 13 on which the individual sheets are stacked in the form of a stack 14, so that after reaching a certain stack height, the pallets can be moved away with the stacked sheets 14 from the field of punching and embossing machine 100.
In the respective processing stations 2, 3, 4 are sensors 30, which determine the exact position of the gripper carriage 8 by receiving signals emitted by the signal transmitters 31 of the gripper carriage 8. The values determined by the sensors 30 are transmitted to the machine controller 15 for evaluation. The machine control 15 has an interface for displaying and entering machine parameters.

Fig. 2a shows a section Fig. 1 in detail. From a feeder 1 sheets 6 are separated and passed over a feed table 16 to the transport system 7 of the sheet punching and embossing machine. The sheet 6 is doing over bands, which in Fig. 2a Not are shown, moved in the sheet transport direction B via the feed table 16. By front marks 21 and page marks 28 of the sheet 6 is mechanically anticipated. In this pre-aligned position, a sensor 20 detects the leading edge of the sheet 6 or print marks printed on the sheet 6. The determined measured value is forwarded by the sensor 20 to the machine control 15. In the machine control 15, the actual position of the sheet 6 is compared with its desired position, wherein the desired position is calculated in the machine control from the sheet format. To compensate for the difference between the actual and desired position of the sheet 6 is corrected by an integrated in the feed table 16 system for page orientation in its lateral position. The page orientation system (in Fig. 2a not shown), for example, as a side-puller, comprising a driven by an actuator conveyor belt may be formed.

Fig. 2b shows a plan view of a sheet 6 in its position on the feed table 16. The front marks 26, the side marks 28 and their controls have not been shown for clarity. In its front area, viewed in the direction of sheet transport B, the feed table 16 has a strongly reflecting surface and is provided with a reflective foil 22, for example. This reflective foil 22 extends to the area which can be measured by the sensor 20. The sheet 6 is printed with an inhomogeneous print image 25. Between the outer edges of the sheet 6 and the edges of the inhomogeneous printed image 25 is an unprinted sheet edge 27. The sheet 6 was further provided with print marks 23. These are both - viewed in the sheet transport direction B - in front of the leading edge 26 of the printed image 25, as well as right and left adjacent to the lateral edges of the print image 25. The front print marks 23 are used to measure the position of the sheet 6 for circumferential alignment, the lateral print marks 23rd serve to measure the position of the sheet 6 to the page orientation

From the print data, the distance of the sheet leading edge 24 from the leading edge of the print image 26 and also the distance between the leading edge of the sheet 24 and the front print marks 23 is known. The same applies to the side edges and the lateral print marks 23.

Based on these known data, the measuring field can be determined, which is measured by the sensor 20 for determining the position of the sheet 6.

In Fig. 3 the stationary part of the sheet transport system 7 is shown. The sheet transport system 7 has two mutually parallel circumferential guide rails, which consist of a plurality of stator segments 40. Along the guide rails of the sheet transport system 7 in the sheet transport direction F gripper carriage 8 can be moved through the processing stations 2, 4. The gripper carriage 8 have anchors (in Fig. 3 not shown), which act together with the stationary stator 40 as linear motors.
In the area of the processing stations 2, 4, the guide rails are particularly finely divided by a large number of stator segments 40. This ensures that a gripper carriage 8 (in Fig. 3 not shown) and transported with grippers on the gripper edge of the sheet sheet 6 can be stopped accurately. Each stator segment 40 is a frequency converter (in Fig. 3 not shown) associated with the construction of a magnetic field in the stator 40, which is controlled by a central controller 15.

LIST OF REFERENCE NUMBERS

1

investor

2

punching station

3

stripping

4

boom

5

machine housing

6

bow

7

Sheet transport system

8th

gripper carriages

9

under table

10

overtable

11

trimmings

12

dare

13

palette

14

delivery pile

15

Control with interface and input devices

16

feed

20

sensor

21

front lays

22

reflective tape

23

print mark

24

Sheet leading edge

25

inhomogeneous print image

26

Leading edge print image

27

unprinted margin

28

page brand

40

stator

100

Sheet punching and embossing machine

B

Sheet transport direction

e

Sheet transport plane

Claims (6)

1. A method for measuring the position of a sheet (6) made of paper, cardboard, a polymer or the like in an adjustment plane (16) in the feeder (1) of a printing machine or print finishing machine (100) having at least one optical sensor (20), wherein the adjustment plane (16) has a strongly reflective surface (22) at least in the region of said at least one sensor (20), characterized in that it comprises the following steps:

   a) determining whether the sheet (6) has a mark printed thereon (23),

   b) optionally entering a nominal distance between the sheet edge (24) and the mark (23) into the control unit of the sensor (20) and determining the measuring field to be monitored by the sensor (20) using the control unit,

   c) monitoring the measuring field by the sensor (20),

   d) determining the position of the mark (23) or the sheet edge (24) and thereby of the position of the sheet (6) by the sensor (20).
2. A method for adjusting a sheet comprising a process according to claim 1,
   characterized in that
   an adjustment of the sheet (6) follows as the last step.
3. A method for the lateral adjustment of a sheet (6) made of paper, cardboard, a polymer or the like in an adjustment plane (16) of the feeder (1) of a printing machine or print finishing machine (100) having at least one optical sensor (20) and a device for the lateral adjustment of the sheet (6), wherein said sheet (6) can have one or more marks printed thereon, comprising the following steps:

   a) once-only determination of the target difference distance between the printed mark (23) or the edge of the sheet (24) and the zero-point of the sensor and entering into the machine control (15) of said printing machine or print finishing machine (100),

   b) determination of the position of the sheet (6) using a process according to claim 1,

   c) determining the effective difference distance transverse to the sheet transport direction (T) between said printed mark (23) or the edge of said sheet (24) and the zero-point of the sensor (20),

   d) transferring the value of the effective difference distance to the machine control (15),

   e) driving/activating said device for the lateral adjustment of the sheet (6) corresponding to the difference between the effective difference distance and the target difference distance by the machine control (15),
   wherein steps b) to e) are repeated for the lateral adjustment of each sheet.
4. A process for setting a device for the lateral adjustment of a sheet (6) made of paper, cardboard, a polymer or the like in an adjustment plane (16) of the feeder (1) of a printing machine or print finishing machine (100) having at least one optical sensor (20) and a device for the lateral adjustment of the sheet (6), comprising the following steps:

   a) performing steps a) to e) according to claim 3,

   b) punching at least one sheet (6),

   c) comparing the deviation between the printed image and the punched image,

   d) correcting the zero-point of the sensor (20) by the deviation determined in c).
5. The process according to any one of claims 1, 3 or 4,
   characterized in that
   said sheet (6) is pre-adjusted mechanically.
6. A process for the circumferential adjustment of a sheet (6) made of paper, cardboard, a polymer or the like in an adjustment plane (16) of the feeder (1) of a printing machine or print finishing machine (100), wherein said printing machine or print finishing machine (100) comprises at least one optical sensor in the region of said adjustment plane (16) of a feeder (1) of said printing machine or print finishing machine (100), and that the printing machine or print finishing machine (100) further comprises a transport system (7) for transporting said sheets (6) through the machine (100), said transport system (7) comprising gripper carts (8) provided with grippers for gripping said sheets (6), wherein said gripper carts (8) are driven by electrical linear drives (8, 40) having alternating current motors, and wherein the sheet (6) can have at least one mark (23) printed thereon; comprising the following steps:

   a) once-only determination of the target difference distance between the printed mark (23) or the edge of the sheet (24) and the zero-point of the sensor (20) and entering into the machine control (15) of said printing machine or print finishing machine (100),

   b) mechanical pre-adjustment of said sheet (6) by feeding the sheet to front marks (21) of said printing machine or print finishing machine (100),

   c) determining the position of the sheet (6) with a process according to claim 1,

   d) determining a difference distance in the sheet transport direction (T) between said printed mark (23) or the edge of said sheet (24) and the zero-point of the sensor (20),

   e) transferring the value of the difference distance to the machine control (15),

   f) determining the difference between the effective difference distance and the target difference distance as a sheet-specific correction value,

   g) driving/activating said linear drive (40) by said machine control (15) considering said sheet-specific correction value,

   wherein steps b) to g) are repeated for the circumferential adjustment of each sheet.

Images