EP0753409B1 - Sheet printing press - Google Patents

Abstract

The printed sheets are deposited on top of a stack of them in the boom and have print-monitoring strips (10) at and parallel to their leading edges, whose measuring panels are scanned by a photoelectric measuring unit travelling along a cross-member. First and second stops align the sheet during the measuring operation. The second stop (9) has components (5) operated so as to hold subsequent sheets up for a predetermined period. The measuring unit (8) is inserted in the space above the sheet and below the components. The latter, which extract samples, can consist of extensible fingers at intervals over the width of the stack (2). The measuring operation can be initiated by a control and evaluation unit with sensors (11) detecting the stack side from which the measuring operation starts.

Description

The invention relates to a sheet-fed printing machine, in particular a sheet-fed offset printing machine according to the preamble of claim 1.

In sheetfed offset presses, the sheets are printed in the individual printing units and then placed on a boom stack. There are front edge stops in particular attached, by means of which the front edges in the sheet conveying direction the sheet comes to rest on the top of the stack in a defined manner. To the Checking and, in particular, regulating ink application in the individual printing units to be able to, it is known in the sheet running direction near the leading edge of the sheet control strips with individual measuring fields extending transversely to the format width of the sheet to arrange. This pressure control strip can then be scanned photoelectrically the remissions thus obtained (densitometric, colorimetric, spectral) for a process control or process control. Is widespread the method of pulling a sheet to be measured out of the stack (sample sheet removal), placed on a measuring table and with one the pressure control strip scanning traversing measuring device is scanned.

Disadvantageous in the method of scanning a print control strip described above is that an operator has to take the sample sheet, which on the one hand associated with handling effort and on the other hand a certain arbitrariness regarding the sample distribution of the sample sheets. Measuring devices are also known become, which in particular summarized in a print control strip Scan measuring fields within the machine, ie "in-line" when the machine is running. Preferably camera systems are used here. A disadvantage of such devices is the relatively high effort for lighting as well as for guiding the arch in a defined Distance to the scanning optics. Especially with large format printing presses Acquisition of the entire format width often also multiple camera systems side by side   can be used, which increases the construction effort. It should also be noted that that especially in high-speed printing presses that are often very small in the direction of sheet travel extensive measuring fields thus only result in a very short measuring time, which is time-critical Operations.

DE 3 108 469 C2 describes a device for measuring ink layer thicknesses in one Printing machine known, whereby a so-called measuring roller is used here the sheet deposited on a delivery stack or its control strip is scanned can be. So that the sheets still to be deposited are not on this measuring roller during of the keying process, sheet holders are provided, which are similar to an automated stack change, the sheets are deposited on a partial stack. There is a pressure control strip to be scanned by the measuring roller described also to be arranged at the rear end of the sheet in the direction of sheet travel. Here is as disadvantageous to see that the sheet end due to the tear, especially on a blanket cylinder is often very deformed or wavy. In addition to that in optical terms the structure of the measuring roller, which is complicated to observe, results from the above Problems with waviness of the trailing edge of the sheet also have the disadvantage that there are no defined image ratios across the arc width of the arc.

From DE 4 207 107 C1 a photoelectric measuring device is also known, which is assigned in the sheet running direction of the front edge of the delivery stack and by means of which is a pressure control strip assigned to the leading edge of the sheet in the direction of sheet travel is palpable. For this purpose, the photoelectric measuring device is on a traverse, which extends across the format width of the delivery stack. Through controllable Gripper opening curves can either be exactly on the stack or the sheets can also be stored offset in the sheet running direction by a predetermined distance, so that the traversing photoelectric measuring device detects the protruding sheet or can scan the print control strip on it. A disadvantage of this device is that the sheets to be scanned are placed offset to the sheet stack, which ultimately results in a stack that is not or not readily available for further processing is usable.

The object of the present invention is therefore a device according to the preamble   of claim 1 in such a way that a sampling of one of the Print control strip assigned to the print edge in the delivery stack is possible is without the stack formation necessary for further processing being impeded.

This problem is solved by the characterizing features of claim 1. Further training the invention emerge from the subclaims.

According to the invention it is provided that a photoelectric movable on a traverse Measuring device scans the pressure control strip on the leading edge of the sheet while the holding-up device used to take the sample sheet is the following and otherwise the Hold the pressure control strip and the sheet obstructing the measuring device. A An advantage of the invention can be seen in particular in the fact that here bow support is used find that are already provided in the machine and the sample sheet to serve. The photoelectric measuring device can be a densitometric, act colorimetric or spectrophotometric measuring device. With one according to the invention trained device can be provided that after a fixed Program cycle sample sheets can be measured. It is particularly possible use different measuring cycles during different process phases. While During production, it is possible to measure a test sheet, for example every 500 sheets. After a stopper, for example, a measuring process would have to be provided every 50 sheets. During the particularly critical phase of the machine start-up, everyone could 20 sheets a measuring process must be provided.

Fig. 1

die erfindungsgemäße Meßvorrichtung während der normalen Bogenablage,

Fig. 2

die erfindungsgemäße Meßvorrichtung während des Abtastens eines Bogens,

Fig. 3

perspektivisch die erfindungsgemäße Meßvorrichtung während eines Meßvorganges,

Fig. 4

eine Draufsicht auf den Auslegerstapel mit der erfindungsgemäßen Meßvorrichtung, und

Fig. 5

die Ansicht der erfindungsgemäßen Meßvorrichtung im Detail.

Furthermore, an embodiment of the invention is explained with reference to the drawings. It shows:

Fig. 1

the measuring device according to the invention during normal sheet placement,

Fig. 2

the measuring device according to the invention while scanning a sheet,

Fig. 3

perspective the measuring device according to the invention during a measuring process,

Fig. 4

a plan view of the boom stack with the measuring device according to the invention, and

Fig. 5

the view of the measuring device according to the invention in detail.

Fig. 1 shows the delivery 1 of a sheetfed offset press, not shown, with a stack 2 set therein. In a manner known per se, the sheets are over here endless circulating chains guided gripper systems from a last sheet guiding Cylinder or drum removed and placed on the top of the stack 2. Of the Stack 2 is placed on a vertically movable stack lifting plate 3, so that the upper edge of the stack 2 within a predetermined tolerance range at the same height remains.

At the upper edge of the stack 2, the sheet is pivotable leading edge stops in the sheet running direction 4 arranged, which is a vertical as shown in Fig. 1 Take orientation so that the deposited sheets are straight with their front edge Reveal front of stack 2. Work with the swiveling front edge stops 4 furthermore, so-called sheet holders 5, which are used for sample sheet removal have retractable and extendable fingers 6, these being shown in the illustration according to FIG. 1 Finger 6 are in the retracted state.

In Fig. 1 and 2 it is shown that on a traverse 7 transverse to the width of the on the A measuring device 8 is attached to stack 2 of the sheets lying thereon. This will via not shown and known drives and funding along the Extend the traverse 7.

Based on the situation shown in FIG. 1, which is the normal storage of sheets corresponds to the stack 2, the sheet holder 5 are now activated, their fingers 6 can be moved from the retracted position (FIG. 1) to the extended position. At the same time additional stops 9 are extended, which prevent the on the fingers 6 of the sheet holder 5 with its front part of the sheet deposited over the Shoot out the front edge of stack 2. The front edge stops 4 from the upright position according to FIG. 1 into a horizontal position according to FIG. 2   panned. The components listed are pneumatic by means not shown and / or electrically controllable actuators from a still further below explained control and evaluation device operated remotely. Now with its front area on the fingers 6 of the sheet retainer 5, the sheets are deposited with the upper edge a wedge-shaped gap in the sheet that was finally completely deposited on stack 2, which releases the pressure control strip 10 attached to the front edge of the sheet, so that the measuring device 8 can scan this.

FIG. 3 shows the situation according to FIG. 2 in perspective. Are shown here the extended fingers 6 of the sheet holder 5, not shown, and the vertical Additional stops 9 extended downwards. As can be seen, the stops 9 are immersed in the spaces between the individual front edge stops 4 designed as tabs. 3, a measuring process was carried out by the measuring device 8 initiated, here the measuring device 8 from one to the left of the stack 2 Parking position the traversing process of the print control strip 10 begins. In the illustration 3 can also be seen, such as here according to the embodiment provided two fingers 6 hold up the sheets lying thereon.

Fig. 4 shows again the top of the stack 2 or the sheet lying thereon the pressure control strip 10. The finger 6 not shown in this figure the sheet holder 5 is hindered sheets for storage on the top of the stack 2 not shown here. The ones swung into the horizontal position are shown Leading edge stops 4 and those on the not shown and on the fingers 6 of the Sheet holder 5 deposited sheet acting additional stops 9. The on the Traverse 7 movable parallel to the direction of extent of the pressure control strip 10 Measuring device 8 is here in a parking position to the left of stack 2. Now that the device according to the invention from an arrangement according to FIG. 1 in the arrangement provided for scanning a sheet or its print control strip 10 2 has been moved, there is now a traversing movement of the measuring device 8 initiated. It can be provided that the measuring device 8 the bow or always runs over the pressure control strip 10 from the same parking position, i.e. after a movement from left to right over stack 2 back to the previous parking position returns. According to the invention, however, it is provided that the   Measuring device 8 each traverse from a current parking position across through the sheet format to a next parking position. A next traversing process is then executed from this parking position. 4 shows that the current Parking position of the measuring device 8 is located on the left of the stack 2 Sensors 11 attached to both ends of the crossbar 7, through which the presence the measuring device is detectable. The sensors 11 are designed as proximity switches. 4, the position of the measuring device is also shown in broken lines on the right of the stack 2 8 reproduced when the measuring device 8 after a scanning operation of the print control strip 10 has moved from left to right. A next measurement for a next test sheet is then triggered from this dashed position.

Fig. 5 shows again in an enlarged manner the arrangement of the movable on the cross member 7 Measuring device 8. The front edge stops 4 are here in the horizontal Position, so that either a measuring process by the measuring device 8 or one per se known sample sheet removal process can be performed. The extended fingers 6 of the sheet support 5 (Fig. 1 to 3) are not shown here. Through the dashed or solid arrows indicate that the measuring device 8th and / or the traverse 7 carrying the measuring device 8 in vertical and / or horizontal Way is movable. It is also indicated that the measuring device 8 additionally one the front edge of the stack 2 can have a scanning device, so that the vertical and / or horizontal traverse 7 and / or the measuring device 8 with respect the traverse 7 just the measuring device 8 always at a defined distance from the front edge of the stack 2 and also to the top of the sheet on the stack 2 is. Also the distance of the measuring device 8 to the surface of the sheet to be scanned is detected by sensor means, not shown, and combined via controllable drives constant value regulated. It is preferably provided that during the scanning process the measuring device 8 via a roller on the top of the sheet to be scanned supports. The roll runs on an unprinted area next to the print control sterile, whereby a constant distance between measuring optics and sheet surface is achieved becomes.

In Fig. 5 is also indicated that the measuring device 8 in terms of its structure is formed so that the under the fingers 6 of the sheet 5   reaching area of the measuring device 8 is as small as possible. In particular takes place here a measuring device 8 use, which both the light-conducting elements Illumination as well as the remissions of the measuring fields of the pressure control strip 10 above Optical fiber or the like.

The devices described with reference to the description of FIGS. 1 to 5, such as the swiveling front edge stops 4, the bow holder 5 with the fingers 6, the additional stops 9, the movable on the crossbar 7 measuring device 8 and the Sensors 11 detecting the parking position of the measuring device 8 are not shown Control and evaluation circuit connected. The control and evaluation circuit causes, as mentioned at the beginning, that in particular in certain programmable Measuring cycles of test sheets are measured, for which purpose the front edge stops 4 from a move vertically into a horizontal position, the fingers 6 of the sheet support 5, additionally stops 9 extended and then the traversing of the measuring device 8 is initiated. In addition, the control and evaluation circuit can still be used with a manual actuation device can be provided, so that a measuring process also manually can be triggered. A further actuating element can also be provided, by means of which the fingers 6 of the arch support 5 can be extended along with the stops 9, without a measuring process of the measuring device 8 being initiated. Is in this situation then a test sheet can be removed from the top of the stack 2 in a manner known per se.

The control and evaluation circuit also reads from the measuring device 8 during a Traversing process via the pressure control strip 10. In particular, it is provided here that those arising from the pressure control strip 10 Measured values of the individual control fields are saved. Depending on the parking position, detected by the sensors 11, ie the position from which the measuring device 8 executes the measuring process, then the individual measured values for zonal assignment sorted. After the individual stored measured values the individual zones of the Color dosing can be assigned based on specified target values in connection With the actual values recorded in this way, an automatic adjustment of the ink supply be initiated in the sense of a regulation.  

Reference list

1

boom

2nd

stack

3rd

Stack support plate

4th

Leading edge stops

5

Bow holder

6

finger

7

traverse

8th

Measuring device

9

attacks

10th

Print control strips

11

sensor

Claims (10)

1. Sheet printing press, particularly an offset sheet printing press, in which printed sheets can be deposited in a delivery on the upper side of a pile and a print control strip arranged in the sheet running direction relative to the front edge of the sheet can be sensed by means of a photoelectric measuring device movable along a cross-member, wherein the cross-member extends across the format width of the sheets characterised in that the delivery (1) has sheet lifters (5) by means of which the front region in the sheet running direction of sheets to be deposited on the upper side of the pile (2) can be held up and the measuring device (8) is movable below the sheet lifters (5) and above a sheet with the print control strip (10) lying on the upper side of a pile (2) .
2. Sheet printing press according to Claim 1, characterised in that the delivery (1) has front edge stops (4) swivellable from a vertical into a horizontal position for aligning the uppermost sheet of the pile (2).
3. Sheet printing press according to Claim 1 or 2, characterised in that the several sheet lifters (5) arranged spaced across the format width of the sheets of pile (2) have retractable and exendable fingers (6).
4. Sheet printing press according to Claim 1, 2 or 3, characterised in that as well as the sheet lifters (5), stops (9) are additionally provided by means of which the sheets prevented by the sheet lifters (5) from deposition on the upper side of the pile (2) can be brought into a defined front edge position.
5. Sheet printing press according to one of the preceding Claims, characterised in that a measuring process of the photoelectric measuring device (8) can be triggered by means of a control and evaluation device operatively connected with this, which additionally is operatively connected with sensors (11), by means of which it can be determined from which side of the pile (2) the measuring device (8) starts the traversing process.
6. Sheet printing press according to Claim 5, characterised in that by the control and evaluation device, a storage of the measured values sensed by the photoelectric measuring device (8) at the print control strip (10) takes place and thereafter a coordination of the stored measured values can be carried out corresponding to the metering zones of the inking unit.
7. Sheet printing press according to Claim 5 or 6, characterised in that via the control and evaluation device, both traversing processes for the photoelectric measuring device (8) and also a manual test sheet removal process can be triggered, for which, according to choice following activation of the sheet lifters (5), a or no traversing process of the measuring device (8) is initiated.
8. Sheet printing press according to one of Claims 5-7, characterised in that by means of the control and evaluation device, both via an actuation element manually and also automatically in programmable cycles, predetermined measuring processes by the measuring device (8) can be triggered.
9. Sheet printing press according to one of the preceding Claims, characterised in that the measuring device (8) is movable in vertical and/or horizontal direction with reference to the front edge of the pile (2) seen in the sheet running direction of the sheets.
10. Sheet printing press according to one of Claims 5-9, characterised in that during a measuring process by the photoelectric measuring device (8), a pile lifting drive effecting a vertical movement of the pile (2) is locked against movement by the control and evaluation device.