EP1153747B1 - Device for managing the printing faults detected within a printing machine - Google Patents

Abstract

A device for processing of printing defects detected in a printing machine which in a first phase delivers a printed support. The printing defects (20, 21, 22) on the support (1) are detected in a detection station. A database connected to the detection station can simultaneously store information relating to each detected printing defect. The processing device connected to the database can, in a second phase, process the stored information in order to evaluate the quality of overall printing of the printed support and can use various possible scenarios, even before the support (1) is cut in a third phase, to define all those portions (23) of the support which should be removed in order to improve the final quality of the printed product within the limit of a restriction in the number of portions which it has been agreed to cut out.

Description

The present invention relates to a device for managing printing defects detected in a printing machine delivering a printed product for the packaging industry from a medium such as sheets or strips. paper, cardboard or other flexible material such as polyethylene for example.

The present invention essentially relates to a decision support tool that makes it possible to visualize, for example in a schematic, tabular or image form, the whole of a support such as a band tainted by all its defects previously detected by a conventional device. Thanks to the application of various virtual filters, this tool makes it possible to visualize several cases representative of the quality level of the band and to count and to identify in each case all the portions of band covered with defects too marked that it would be necessary to to eliminate, this even before undertaking an irreversible action of cutting and ejection of defects of the band.

The production of flexible packaging, resulting precisely from web materials, goes through different successive phases that require several rewinds and consecutive windings of the reels to pass from the printing of the tape to the packaging of the products for which these packages are intended.

In a first step, it starts with the printing of the tape from a virgin reel of a width that can generally contain several generally identical packaging footprints. The number of fingerprints thus arranged side by side over the width of the band defines the number of tracks that comprise this band. Once printed, the web is dried and examined by a device for detecting, recognizing and accounting for all types of print defects it may present. These defects are identified in a Cartesian system and stored by the detection and location device which records their position relative to an origin, in the longitudinal direction, and with respect to the different tracks they occupy, in the transverse direction. Some devices make it possible to detect so-called "nascent" defects which generally result from wear or a drift of one of the organs of the press and which can only increase as you print. The finding of any defect will cause the intervention of the operator of the machine which will mark the approximate place where the defect was detected by the installation of a butterfly (cardboard tongue) on the band so that once the rewound tape, the butterfly slightly protrudes from its edge and is easily spotted. This intervention can also be done through an automatic labeler. If necessary, the driver of the machine will even be forced to stop printing to remedy the possible cause of an incipient defect before it becomes more tolerable. Once inspected, the printed web is then rewound for machines delivering a rolled product, as opposed to products in the form of sheet elements.

The second step of the conventional process is to take the printed coil and cut it longitudinally to form as many new small reels as there are tracks on the tape. To do this, the printed strip will be unrolled progressively when it is introduced into a rotary cutter which will divide it in the longitudinal direction along the path defined by the delimitation of the tracks it contains. During the course of the course of the tape, the driver will have to pay close attention to the approach of all the butterflies which were previously affixed on the band. The tape must be stopped at the arrival of each butterfly and the driver will be forced to find the defect found, look where it starts and where it ends before removing it by two cross sections in the tracks concerned. Released from their defective portion, the corresponding ends of these tracks will be glued together by means of an adhesive tape for example. All the tracks will then be rewound simultaneously before being delivered, in the form of independent coils, to the customer who will proceed to the packaging of his products by unrolling each of these small coils again in a third and last stage.

It is in the second step, before the beginning of the transformation of the printed coil, that the object of the present invention finds its use mainly. Printing error detection devices, such as those mentioned above and illustrated in the patents, are already known. EP 452 769 and EP 554,811 , which can be used to visualize faults appearing on a tape or plate elements during printing by means of cameras and control screens.

Printed webs can either be used as a base material for machines producing packings made as plate elements, or they can be reworked and re-stored as smaller rolls for packaging products using rolls. packaging. If the first category of products made allows a very easy handling, especially when it comes to eliminate and eject from the production line all the defective elements, we understand very well that it does not go likewise to perform such an operation from products stored in the form of continuous strips. In the case where the final product of the packaging production is a continuous web stored as a reel, it becomes indeed difficult and much more expensive to remove all the web portions that have been judged to be defective. During the first step, the elimination of such portions would require the complete shutdown of the printing machine, which of course would seriously hamper the production rate and could lead to other successive problems of printing during the always delicate phase , restarting the press. The elimination of these defective portions during the second step causes the same problems, which this time relate to the rotary cutter. However, this machine has the advantage of being a simpler constitution and less fragile causing no particular risk for the band when it is forced to follow repeated stops and repeated starts.

The number of connections present in the final coil, however, largely determines the estimate of its quality and naturally affects its selling price accordingly. For technical reasons easily verifiable, it turns out that the tape connections regularly pose problems in the packaging machines products that constitute the third stage of use of these coils. As a result of these problems, many customers generally require that these coils do not include more than 2 or 3 fittings to the detriment of residual print defects that they may still contain.

The patent JP-A-58224754 describes a device according to the preamble of claim 1. This device allows to view the state of the band in its entirety with its defects in order to be able to manage by different scenarios, a priori unlimited number. Each of these cases becoming representative of a certain modulation of the degree of tolerance of these defects, in order to optimize production and obtain the best compromise. possible between the maximum number of connections allowed by the customer and the number of residual defects that may still be considered eligible.

The purpose of the present invention is therefore to provide a tool to assess overall the quality of the printing of the tape and to define, using different possible scenarios and even before undertaking an irremediable cutting action, all the portions that it would be wise to delete in priority from the maximum number of tape connections admitted by the customer.

This object is achieved by means of a device according to claim 1.

• La figure 1 est une représentation schématique de l'état d'une partie de bande imprimée.
• La figure 2 est une représentation schématique des principaux organes intervenant dans la phase, telle que connue à ce jour, de l'impression de la bande.
• La figure 3 est une représentation schématique des différents organes intervenant dans la phase de gestion des défauts et de découpage de la bande.

The invention will be better understood from the study of an embodiment taken in no way restrictive and illustrated by the appended drawings in which:

• The figure 1 is a schematic representation of the state of a printed band portion.
• The figure 2 is a schematic representation of the main organs involved in the phase, as known to date, the printing of the tape.
• The figure 3 is a schematic representation of the different bodies involved in the defect management and cutting of the tape.

The figure 1 shows in schematic form the state of a portion of a strip 1 from a rotary printing machine. This strip comprises a primer 2 in its downstream part and two edge edges 3, 4 between which is printed a mosaic pattern 5 left by the printing cylinder of the rotary machine. The printed patterns may be identical or not but each of them will constitute a single packaging after the final stage of production. The patterns 5 are carefully aligned and form, in the case shown, three separate tracks 11, 12, 13. Locating marks 14, which may be self-adhesive tabs, for example, are affixed in one or the other of the edges. bank 3, 4 at a strictly regular interval. Various printing defects 20, 21, 22 are shown schematically in this figure. These defects are differentiated by their degree of importance which is low for tolerable printing defects 20, average for printing defects 21 deemed to be limited, and high for intolerable printing defects 22. A grouping of several intolerable defects 22 therefore justifies the choice of a portion of strip 23 that it would be desirable to eliminate by a downstream cross-section 24 and an upstream cross-section 25. It will be noted that this portion of strip 23 does not necessarily have to contain all lanes 11, 12, 13 and that only the tainted tracks defects will be cleverly cut by the cross sections 24 and 25.

The figure 2 gives a schematic representation of the main organs involved in the printing phase of tape 1, which is the first step in the packaging manufacturing process. From a blank reel 30, of a width such that it can generally contain several imprints or printing patterns 5, the continuous strip 1 passes from upstream to downstream in the direction of displacement represented by the arrow 29. This continuous band passes successively through different stations, the most ordinary of which are an introduction station 31, from which the band is issued, one or more printing and drying stations 32, a detection and location station 33 printing defects, a station or traction group 34, for tensioning the band and compensating voltage fluctuations by means of a player, and finally a receiving station 36 in which the continuous band 1 is stored in form printed coil 37.

During the printing phase, it is possible that the strip 1 is marred by various printing defects 20, 21, 22 among which may be mentioned, for example, absences, surplus or projection of ink, oil stains from a part of the machine, or staggering or marking defects that cause offsets between the basic color prints of the printed pattern. Other more progressive, and less stealthy, printing defects are so-called "nascent" defects which are the warning of ongoing deterioration due to normal wear of one or more parts of the printing machine. such as the ink scraper, the printing form or the pressure roller. Although initially at the limit of tolerance, these defects evolve and grow over the print until they become excessive and intolerable.

It is in order to be able to detect all these defects that once printed the band 1 passes through a reading unit 40 constituted by at least one camera 41, the field of view of which is clearly visible by a lighting device 42, and a measuring instrument 43 making it possible to synchronize the acquisition of the image with the scrolling of the band 1. The camera 41 is connected to a control unit 45 which takes account of these defects and this control unit is connected to a control monitor 44 which allows the view. A pulse generator 46 schematically links the printing and drying station 32 to the control unit 45. This pulse generator 46 constitutes the clock of the station 33 for detecting and locating defects. Depending on the printing speed, it makes it possible to compensate for registration errors which result essentially from normal variations in the tension and the length of the strip, which errors thus distort the rigor of the information transmitted by the measuring instrument 43. The latter simply consists of a rubberized caster entering, without sliding, in permanent contact with the band 1 and delivering between one thousand and two thousand pulses each turn of roulette for example. The pulses of the generator 46 are transmitted to the control unit 45 which, in combination with the pulses delivered by the measuring instrument 43, can thus locate on a virtual longitudinal axis, representative of the length of the strip 1, the abscissa at which a fault 20, 21, 22 has been detected. The camera 41 makes it possible to detect in which track 11, 12 or 13 are the defects encountered.

The control unit 45 is thus able to locate, along two perpendicular axes, the position of the defects 20, 21, 22 on the strip and to inventory them according to their characteristics and their rate of recurrence for example. All this information is stored in a database 47 connected to the control unit 45. The origin of the longitudinal axis used to identify all the printing defects is indicated by the first registration mark 14 affixed by a device. marking mark 48 in the edge edge, 3, 4 of the strip 1. In order to limit systematic errors and improve the accuracy of the identification of defects, several marks 14 will be affixed to the strip 1 at strictly regular intervals. These marking marks 14 will each constitute a new origin which will be taken as a reference in the second stage of the process of elaboration of the strip 1. This device 48 may be for example a labeler controlled by the control unit 45 as a function of the pulses. received by both the measuring instrument 43 and the pulse generator 46.

The figure 3 is a schematic representation of the various organs involved in the cutting phase of the band 1, which phase is the second step in the packaging manufacturing process as described above. The printed coil 37, formerly issued from the receiving station 36, is placed in a new insertion station 50. The latter is located upstream of a second production line which successively makes it possible to manage, according to the present invention, all the data relating to the printing defects 20, 21, 22, previously stored, then begin cutting the printed tape 1 according to the best compromise evaluated by a device 51 for managing these defects. This device also makes it possible to control all the cutting operations of the strip 1 which, for the most part, take place in the direction of its displacement 29 by means of rotating blades of a longitudinal cutting station 52 and a sporadically perpendicular to its direction of travel 29, by means of a transverse cutting device 53. It is during the longitudinal cutting that the tracks 11, 12, 13 will be separated from each other and the edges of the edge 3, 4 of band 1 will be eliminated. Having become independent, these tracks will be finally wound a last time in a second receiving station 55 to form narrower coils 56, 57, 58 constituting the final product of this production line. It goes without saying that the number of these reels is directly a function of the number of tracks that contains the tape once printed.

As provided in the embodiment of the present invention, the printing defects management device 51 comprises a reading unit 60 connected to a management unit 65 and a stored data management interface 70, placed between the base 47 and the management unit 65. The reading unit 60 is composed of two reading devices, namely a marker 61 of registration marks 14 and a second measuring instrument 62 whose utility is perfectly identical to that of from his counterpart 43 described previously. The purpose of the detector 61 is to re-synchronize the identification of defects with the sometimes unstable scrolling of the strip, thanks to the detections of the registration marks 14 previously defined as perfectly known fixed origins. The measuring instrument 62 is directly connected to the management unit 65 while the detector 61 is indirectly connected thereto via a second pulse generator 63. provide a digital synchronization top with each passage of a registration mark 14.

The management unit 65 constitutes the pilot element of the entire device 51 for handling printing defects. It controls the advance and the longitudinal cutting of the web 1, by acting on the common drive of the insertion station 50, the longitudinal cutting station 52 and the receiving station 55, but also controls the blade of the transverse cutting station 53 in the case where the latter is automated. The management unit 65 manages the operation of all these organs according to the information it draws from the interface 70 for managing the data relating to the defects processed. This interface includes a processing unit 71, comparable to the console of a computer. It is through this interface 70 that the driver of the machine can manage and process all the information that has been previously collected in the database 47; the latter being connected to the processing unit 71. The interactive dialogue between the driver of the machine and the processing unit 71 is via an output device 72, such as a monitor, and an input device 73 may be a keyboard, a mouse or the touch of a screen for example. The processing unit 71 is still connected to a bank of filters 74 whose use is described below. Being composed of units forming a standard computer station, this interface 70 could advantageously be set back from the production line, in a control room away from noise for example.

The operation of the printing defects management device 51 is as follows: Having access to all the information which notably describes the type, the importance and the location of each of the defects 20, 21, 22 inventoried, the unit processing 71 is able to return all these data to the operator who can then view them on the monitor 72. This information can be presented in an image or tabular form or, like the figure 1 , in schematic form more illustrative but still corresponding to the current state of the tape stored in the printed coil 37. The management by the processing unit 71 of the information recorded in the database 47 can bring additional events arising from statistical results on the entire length of the strip. This combination of information brings many advantages that will allow for example to quantify the Overall print quality of the tape, visualize all critical areas where printing is of poor quality, and simulate different clip-out scenarios based on the application of a number of virtual filters masking defects judged to be of lesser importance.

For this purpose, the operator can have access to various computer tools that make it possible to create said virtual filters and then store them at will in the bank of filters 74. These virtual filters are generally in the form of a list of alphanumeric instructions. decodable by a computer system. They include all the conditions that make it possible to exclude the revelation of defects defined as being secondary according to selected criteria. The application of one or more filters, on the data representative of the printing defects 20, 21, 22, makes it possible to better define the ideal locations of the cross-cuts 24, 25 authorized by the customer in a limited number. Knowing the entire history of the printing of the coil 37, the operator will therefore be in the presence of a decision-making tool allowing him to optimize the final quality of this coil. Finally, it should be noted that the creation and selection of the most appropriate filters could be as well defined manually as automatically chosen by means of a search algorithm for example.

Once the final configuration of the transverse cuts 24, 25 has been chosen, the printed coil 37 can begin to unfold and the process of processing that coil can begin. The strip 1 first scrolls under the measuring instrument 62 which counts its footage with respect to the origin of the longitudinal registration system once it has been recognized by the detector 61. This origin is defined first. times by the first registration mark 14 encountered, then successively incremented and replaced by each of the new identification marks 14 recognized as and when the course of the tape 1. Normally, the band 1 continues its way to cross the station longitudinal cutting 52 before emerging in the form of strips whose width corresponds strictly to that of the tracks 11, 12, 13. Knowing each time the abscissa at which is the next transverse cutout 24, 25, the management unit 65 monitors the data transmitted to it by the measuring instrument 62 while taking into account the number of registration marks 14 already encountered. At the right time, the unit management system sends a signal to the drive devices of the tape in the stations 50, 52, 55 and progressively stops the unwinding of the printed coil 37 so that the downstream cut 24 provided on the band 1 stops at the height of the transverse cutting device 53. The latter can be constituted simply by a cutting instrument such as a blade, arranged perpendicularly to the direction of travel of the strip, which will cut the track or tracks 11, 12, 13 provided with defects to the selected location between two adjacent printing patterns. The upstream portion of the band 1 will then be diverted to waste coils 54 which will store the tracks of all the strip portions 23 to be removed from the band 1. The number of discarded coils 54 is of course directly function of the number of tracks of the band. The upstream cut 25 will be done in the same way. It is then sufficient to reconstitute the continuity of the cut tracks in the band 1 by joining the remaining upstream and downstream parts. A carefully affixed adhesive tape makes this join very easy.

Apart from the direct advantages provided by the device of the present invention, it also appears that the latter could also feed a flow of information used for statistical purposes to know the evolution of the quality of the products made over the course of time. time by providing, for example, a production traceability report for the end customer or for internal use. This information could also make it possible to better manage the maintenance of the printing machines and to predict the appearance of a wear defect before this wear becomes too great. Therefore, some machine parts could be advantageously replaced in time, even before starting the printing cycle, thus avoiding the use of maintenance work very undesirable during printing. Finally, from a more commercial qualitative point of view, said device would also make it possible to confirm and guarantee, by issuing a certificate for example, the minimum quality required by a customer on the reels 56, 57, 58 that would be delivered to him.

The description of the device of the present invention refers to media in the form of reels and continuous webs but it is obvious that these products can be very well substituted by discontinuous sheet elements stored in the form of a stack for example.

Many improvements can be made to the object of this invention within the scope of the claims.

Claims (8)

1. A device (51) for processing printing defects detected in a printing machine which, in a first phase, delivers a printed product (37) starting from a support (1) which, once printed, comprises a number of reference markers (14) attached at rigorously regular intervals and also comprises a mosaic of patterns (5) constituting packaging material disposed in one or more adjacent rows or tracks (11,12,13), together with printing defects (20,21,22) which are detected during the advance of the support (1) in a detection station (33) by using a Cartesian reference system applying to the support (1), the processing device (51) being connected to a database (47) connected to the detection station (33) capable of simultaneously storing information relating to each detected printing defect, the processing device (51) being connected to the database (47) in order, in a second phase, to process the stored information in order to evaluate the quality of overall printing of the printed product (37) and, before cutting the support (1) in a third phase, to define all those portions (23) thereof which should be removed in order to improve the final quality of the printed product (37), characterised in that the information stored in the database (47) is processed by a data-processing interface (70) connecting the database (47) to a processing unit (65) for monitoring, during the third phase, the advance of the support (1) by acting on the means driving it for re-synchronising the marking of printing defects (20,21,22) via the reference markers (14) attached during the first phase, and for extracting all necessary data from processing unit (71) for stopping the support (1) of the printed product (37) in a cutting station (53) at the level of a downstream cross-cut (24) followed by an upstream cross-cut (25), the cuts defining that portion (23) of the support which is to be cut out.
2. A device according to claim 1, characterised in that the data-processing interface (70) comprises the said processing unit (71) connected to the database (47) and to the processing unit (65), an input peripheral (73), an output peripheral (72) for displaying the entire printed product (37) and all the printing defects spoiling it and for delivering at least one production report, and a bank (74) offering a choice of virtual filters for masking at least one detected defect via the output peripheral (72).
3. A device according to claim 2, characterised in that the virtual filters containing all conditions which can exclude revelation of defects defined as secondary under the chosen criterion and in that the virtual filters can be used, produced, destroyed and modified either manually via the input peripheral (73) or automatically by the processing unit (71) after analysis of the information contained in the database (47).
4. A device according to claim 2, characterised in that the portion (23) of the support is defined by the downstream (24) and the upstream cut (25) as a result of a compromise between the number of printing defects remaining after application of the chosen virtual filter to the stored information, and the effect on the entire printed product (37) of withdrawing the said portion (23) of the support.
5. A device according to claim 4, characterised in that the virtual filters comprise a list of alphanumeric instructions compatible with the information stored in the database (47) and decodable by a data-processing system contained in the processing unit (71), and in that a virtual filter can be obtained by combining a number of elementary virtual filters.
6. A device according to claim 1, characterised in that the information relating to the printing defects (20,21,22) stored in the database (47), comprises, in the case of each printing defect, at least the Cartesian coordinates of the position of the printing defect on the support (1), its level of importance and its type defined in accordance with its appearance.
7. A device according to claim 1, characterised in that the station (53) for cutting off portions (23) of the support comprises a cutting element driven by the processing unit (65) to cut that or those tracks (11,12,13) which are defective at the place chosen between two adjacent printing platens (5).
8. A device according to claim 1, characterised in that the detecting of printing defects of a printed product (37) is obtained via a support (1) constituting of a continuous web and/or at least one sheet.

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