WO2017115291A1

WO2017115291A1 - System for detecting and tracing defects during the steps for processing materials

Info

Publication number: WO2017115291A1
Application number: PCT/IB2016/058041
Authority: WO
Inventors: Paolo DE GRANDIS; Guido BARGERO
Original assignee: Grafikontrol S.P.A.
Priority date: 2015-12-29
Filing date: 2016-12-28
Publication date: 2017-07-06
Also published as: ITUB20159538A1

Abstract

A system (1) for detecting and tracing defects during the steps for processing materials, particularly spools or sheets of material obtainable by printing, by means of a printing method with inks based on solvent, water and UV; the system comprises an inspection device (2), a marking device (3), and a detection device (4) configured to read codes (11a, 11b, 11c, 11d) printed on the material (10); the system (1) further comprises: a) a processing unit (5), configured to receive and correlate the signals generated by the inspection device (2) and data generated by the detection device (4); and b) a control apparatus (6) configured to access the control information item and to locate, by means of the control information item, a portion (10a, 10b, 10c, 10d) of material containing a defect.

Description

SYSTEM FOR DETECTING AND TRACING DEFECTS DURING THE STEPS FOR PROCESSING MATERIALS

The present invention relates to a system for detecting and tracing defects during the steps for processing materials, particularly spools or sheets of material that can be obtained by means of a printing process.

The invention also relates to a method and a computer program that are consistent with the system.

In a normal printing process, performed with inks based on solvent, water and UV, for example of flexible packaging, the printed product is normally accumulated in spools which are subjected to subsequent processing steps by using various machines. Each one of these steps can introduce defects on the product or on portions thereof which, if they exceed a certain tolerance threshold, render the product inadequate for the requirements of the client and therefore unusable.

In the background art there are solutions that allow to detect production defects and machines that allow to remove the portions of defective material. If, for example, the product is wound in a spool, an inspection system can detect that the spool contains defects and an operator, after arranging the spool on an adapted machine, typically a cutting and rewinding machine, can unroll it so as to remove the defective portion.

However, these solutions of the background art are not free from drawbacks, which include the fact that the operator, before proceeding with removal, must identify the product and find some information thereon, such as the type of product, and seek the defective portion of material by inspecting all of the material and then proceeding with defect removal. Furthermore, the systems of the background art allow to take into account defects introduced during the production step, for example by printing, of the product, but do not provide adequate tools for detecting defects introduced in subsequent steps.

Furthermore, in a normal printing process (for example of flexible packaging) the printed product is normally accumulated in spools which are subsequently processed on laminators, laminating machines, sheeters or on slitter-rewinders.

In the converting sector, for example, the slitter-rewinder is the machine on which the last processing of the printed spools occurs, i.e., spools of desired width and length are produced as a function of the various formats of the product that will be packaged. These machines for the final processing of the printed materials, which perform finishing processes so as to obtain a product according to the specific requirements of the clients, are often unable to detect defects easily. This causes inconvenience and costs.

The aim of the present invention is to overcome the limitations of the background art highlighted above, by proposing a new system capable of allowing the detection of errors that relate to the various steps of the processing of materials and of obtaining in an efficient manner information required for the removal of these defects.

Within this aim, an object of the present system is that it can be applied on various machines normally used in the processing of materials.

A further object of the invention is to track and render easily accessible information related to detected defects.

Another object of the present invention is to obtain final products that have no defects and have the characteristics required by the client.

Another object of the present invention is to have a structure that is simple, relatively easy to provide in practice, safe in use and effective in operation, as well as relatively modest in cost.

This aim and these and other objects that will become better apparent hereinafter are achieved by a system according to claim 1 , a method according to claim 1 1 and a program according to claim 14.

Advantageously, the system allows to detect the defects automatically and to track each one of the detected defects.

Conveniently, the system allows to integrate the detections with data that can be entered manually by an operator.

Preferably, the system is capable of controlling precisely the machines assigned to removal of the detected defects.

Further characteristics and advantages of the invention will become better apparent from the detailed description that follows, given by way of nonlimiting example, accompanied by the associated figures, wherein:

Figure 1 is a block diagram of the system according to the present invention;

Figure 2 is a view of an aspect of the system of Figure 1 ;

Figure 3 is a flowchart that illustrates the operation of the system of

Figure 1 ;

Figure 4 is a schematic top plan view of a portion of material that can be inspected by the system according to the invention;

Figure 5 is a schematic side view of a diagram of a part of the system according to the invention;

Figure 6 is a schematic top plan view of the part of the system of Figure 5;

Figure 7 is a schematic top plan view of another part of the system according to the invention.

An exemplifying architecture of the system according to the present invention is summarized in the block diagram of Figure 1. In this figure, the system, designated totally by the reference numeral 1 , comprises a device 2 for inspecting a material 10; a marking device 3, a detection device 4, a processing unit 5, a control apparatus 6. The system further comprises other elements 7, 8, 9, 9a, which will be presented with greater detail hereinafter and in particular an interconnection network 12, a motorized positioning device 13 and a sensor 14 for detecting the edge of the material 10.

For example, the sensor 14 can be constituted by an ultrasound device, used in particular if the material 10 is constituted by a transparent film, or by a charge-coupled device (CCD), which can be used in the case of opaque materials, such as paper, cardboard or others.

Hereinafter, it will be assumed merely for the sake of simplicity in description that the product is a spool, in particular a spool of material 10 that can be obtained by means of a printing process, for example of the type with inks based on solvent, water and ultraviolet (UV), and composed of various portions 10a, 10b, 10c, lOd.

The inspection device 2 is provided with means adapted to detect and signal a defect on the material 10. In particular, the inspection device 2 detects printing defects for example present in the substrate of the material. The inspection device 2 can be provided also by using known systems, as long as they are additionally configured, whenever a defect is detected, to send a signal to a processing unit 5. The inspection device 2 can be connected to various apparatuses and in particular can be installed on the machine adapted to print the material 10 in order to obtain a windable flexible product such as a spool.

The marking device 3 is adapted to print, on portions of material 10a, 10b, 10c, lOd subjected to inspection by the inspection device 2, a plurality of codes 1 1a, l ib, 1 1c, l id. Each one of these codes is uniquely associated with a respective portion of material and for this reason they are termed unique codes. For example, the code 1 1c is uniquely associated with the portion 10c. Hereinafter, merely for the sake of simplicity in description, reference shall be made to the unique code 1 1c and to the portion 10c on which it is printed, but it should be understood that the remarks made for the code 1 1 c and for the portion 10c apply also to the other portions and to the respective unique codes. The marking device 3 allows to perform continuous marking of the material 10, preferably by printing the code along one of the two edges of the material 10 (which are normally defined as selvage and normally, but not necessarily, lack printing). Preferably, the marking device 3 comprises an apparatus of the inkjet type 60, which is adapted to print said unique codes. As an alternative, the marking device 3 can be constituted by a printing apparatus of the laser type.

The detection device 4 is adapted to read the unique codes l la-l ld and to identify the positions of the portions of material 10a- lOd uniquely associated with said unique codes. Preferably, the detection device 4 is mounted integrally with the apparatus of the inkjet type, for example on a same mechanical support of the printing head of the inkjet apparatus. The system further comprises a positioning device 13 which is provided with a sensor 14 for detecting the edge of the material 10, which is adapted to position with absolute precision the marking device 3 and the detection device 4 in order to allow repeatability of the unique code 1 lc at a minimum distance from the edge of the material 10.

In particular and in a preferred manner, the sensor 14 is integral with said support and is connected to the control apparatus 6. The support, arranged at right angles to the direction of sliding of the material 10, is actuated by the linear actuator 13, which in turn is connected to the control apparatus 6.

Conveniently, the positioning device 13 can be installed both on the printing machine and on the laminator/extruder and on the slitter-rewinder and doctor rewinder that perform subsequent processes on the material 10. The main function of this device consists in ensuring the repeatability of the printing and reading of the code l la-l ld printed by the marking device 3, with respect to the edge of the material 10. Preferably, the code l la-l ld is always printed close to the edge of the material in a free region 40, which is preferably external with respect to the printed images 30, which can be intended also to print reference notches 1 10, shown in Figure 6, which are used by various apparatuses such as register control devices.

The system according to the invention conveniently provides for the execution of the printing of the codes l la- l ld directly on the material 10 and not on adhesive labels that will be subsequently glued to the material. The various types of material 10 can have variable widths depending on the productions: this is a fundamental aspect in the printing of the packaging. It is therefore of paramount importance that the printing precision with respect to the edge of the material is maintained, since during production variables arise which can displace the material transversely with respect to its advancement direction. Some of these variables are: the tension of the printing material, the automatic speed changing of the spools on the unwinding unit of the printing machine, and so forth. If the material shifts transversely, two problems can arise: if the material 10 shifts inward with respect to the central plane 100, then the code 1 la- 1 Id is printed outside the material 10; if the material 10 shifts outward with respect to the central plane 100, then the code 1 la-1 Id is printed on the area in which the various images 30 that constitute the printed product are printed; in both of these cases, the code 1 1 a- 1 1 d cannot be read during the subsequent steps of the processing of the printed spools, and therefore traceability of processing defects is lost.

With reference to Figures 5 and 6, another aspect is the importance of advancing or delaying the signal (trigger) to the marking device 3 that prints the code 1 l a-1 Id. This need arises from the fact that reference notches 1 10, on which the code 1 1 a- 1 1 d must not be overwritten, can also be printed on the edge of the material 10. With reference to Figure 5, this function of advancing and delaying the moment when the code 1 la-1 Id is printed is provided by the inspection device 2 with which the processing unit 5 interacts. In a starting step of the new production, the operator of the printing machine checks on the monitor of the inspection device 2 the correct position of the code 1 la-1 Id, and if it is found to overprint with respect to the reference notches 1 10 the operator can correct the position by acting directly on the terminal of the inspection device 2.

The sensor 14 for detecting the edge of the material 10 is installed on a motorized guide 13 on which it is integral with the marking device 3. The sensor 14 has advantageously a fork-shaped body in which the material 10 is arranged so that one of its edges Occupies a central region of the fork. When the material 10 moves transversely, the sensor 14 detects this movement and provides a signal to the control unit 90 that actuates the motorized guide 13 to return the edge of the material 10 to the preceding condition. This continuous control allows the marking device 3 to print the code 1 la-1 Id at a preset distance with respect to the edge of the material 10. The detection device 4 allows the verification and decoding of the code 1 1 a- 1 Id and transmits an alarm to the processing unit 5 when the code 1 la-1 Id is not detected.

The importance of printing the code 1 la-1 Id always at the same distance with respect to the edge of the material 10 is essential to allow the detection of the code 1 1 a- 1 1 d on the other machines designed to process the material 10 (laminator, extruder, slitter-rewinder, doctor rewinder). All these machines can in fact have different widths with respect to the printing machine (rotary, flexographic, offset) and the machine operator, when he mounts a spool of printed material to continue its processing, does not necessarily mount said spool in a precise position. The code 1 la-1 Id printed on the material 10 must be detected by the various detection devices 4 of the codes 1 la-1 Id in order to allow identification of the position of the defects, manage machine stops and the consequent elimination of the defects. Accordingly, as shown in Figure 7, a sensor 14 is installed on the other machines as well and is installed on a motorized guide 13 and a device 4 for detecting the code 1 1 a- 1 1 d.

Preferably, as soon as the marking device 3 prints a code, for example 1 1c, the detection device 4, essentially immediately after this printing, reads this unique code 1 1c. This reading is used not only to verify the quality of the code (the code 1 1c can be read also in the processing steps after printing) but is also used to identify the position/meter count of the spool and the position/meter count of the defects thereon. The detection device 4 transmits this information to the processing unit 5. The processing unit 5 is configured so as to process all the data obtained from the detection device 2 and from the marking device 3 and contains or provides access to a data bank comprising information for controlling the defects detected during the various steps of the production of the material 10.

The association of the code 1 1c with the defect detected by the detection device 2 allows the exact identification of the position of the portion that contains a defect and therefore of the defects within the printed spool.

In particular, the processing unit 5 is configured to associate the detections performed by the inspection device 2 with the readings performed by the detection device 4 and on the basis of this association generate a control information item that is adapted to locate a defect on the material 10. In other words, the processing unit 5 associates the position and the moment when the defect was detected by the inspection device 2 with the simultaneous reading of the unique code on the part of the detection device 4.

In the preferred embodiment, for each product, for example spool, said data bank contains the list of the detected defects and their position. Furthermore, this list is preferably provided as a file that can be downloaded by the control apparatus 6 connected to the processing unit 5 by means of an interconnection network 12, for example a dedicated network or a company network.

The unique code 1 1c allows to identify the portion of defective material 10c. In the preferred embodiment, the unique code 1 1c comprises up to ten characters and its length depends or can be adapted to the specific requirements, for example it can depend on the number of spools to be printed and on the rate of marking performed by the marking device 3. The code 1 1 c is printed by the marking device 3 preferably at regular intervals, for example equal to the dimensions of the portion 10c. Preferably, the unique code 1 lc stores various information items, including for example the number/code of the job being processed, the number of the printed spool, the unique position or meter count of the spool being processed. This position is given preferably by the printing pitch.

In one embodiment, the code 1 1 c appears as a series of markings, for example 2 mm high, and with a variable thickness. The length of the code is variable depending on the quantity of printed characters (preferably varying from a minimum of six to a maximum of ten). In one embodiment, the length varies from 38 to 59 mm. This unique code 1 1c has been conceived so that it can be recognized automatically in the subsequent processing step also by the sensors 7 and 8. Furthermore, recognition of the unique code 1 lc is independent of the travel direction of material.

The control apparatus 6 is adapted to access the control information and to control a machine assigned to the removal of the portion of defective material.

This machine typically performs the last process on the material before delivering it to the client ("final machine").

In the converting sector, for example, the slitter-rewinder is the machine on which the last processing of the printed spools mounted thereon occurs, and allows to produce spools of chosen width and length as a function of the various formats of the product. The spool is mounted on the machine and can be wound and unwound by said machine. The control apparatus 6 can be installed on said final processing machine and has the purpose, during the unwinding of the spool mounted on the machine, of detecting automatically which (previously printed) spool is subjected to unwinding and to identify the position associated with the defect introduced during the printing step or during other processing steps. In particular, the apparatus 6 reads the unique code 1 1c printed on the spool to be cut and, by means of identifying information stored therein, downloads from the processing unit 5 the defect map file related to the spool being processed. In this manner it is possible to have the list of the defects that are present on the spool. The control apparatus 6 is therefore capable of calculating the moment when the slitter-rewinder is to be decelerated and stop it at the exact point where the material is to be rejected. The operation for removing the waste material can occur in various manners. For example, it is performed manually: the operator cuts the spool transversely, removing a given number of turns of printed material.

After removing the defective material, the portions that are adjacent to the removed one (leading end and trailing end) are glued.

Advantageously, the control apparatus 6 is capable of taking in account this removal, of synchronizing and of establishing which portion of material has been subjected to processing. Preferably, the system according to the present invention allows to calculate the removed defective material or waste (expressed in kg or other units of measure) by connecting the control apparatus 6 to an electronic balance.

If information related to the weight of the substrate (for example in g/m²) is available, it is possible to calculate the weight of this removed portion by deducting it from the subsequent unique code (for example l id) and the preceding code (for example 1 1 b) with respect to the one or ones that belong to the removed portion or portions (for example 1 1c). Advantageously, the apparatus 6 can also be installed not only on a final processing machine (slitter-rewinder, sheeter or the like) but also on machines that perform intermediate processes (for example a machine of the type of a spreader, laminating machine, laminator extruder, doctor rewinder), i.e., the operations performed prior to the operations performed by the "final" machine. In this case also, the apparatus 6 has the purpose of detecting automatically the product, for example which spool is subjected, optionally by unwinding it, to intermediate processing operations. The apparatus 6 therefore can also be configured to send an information item, termed second control information item, to the processing unit 5, indicating any defects introduced during the intermediate processes. The processing unit 5, on the basis of this information, updates the list that contains the printing defects, adding the ones detected during the intermediate processing steps to the ones detected during the printing step. In order to detect these errors introduced in the intermediate steps, the apparatus 6 can be equipped, in case of installation on intermediate machines, at least with a sensor 7 that is adapted to read the unique code 1 1c and with means for interconnecting to at least one inspection device 2. If the product is a spool, the intermediate process might consist in connecting two spools: this operation consists in unwinding one spool completely and gluing the end portion of a spool X to the initial portion of another spool Y in a continuous manner. This adhesive bonding between the two spools entails a momentary loss of the reading synchronization on the part of the sensor 7.

Owing to the complexity in detecting the data of the unique code 1 1 c at certain speeds, the sensor 8 is used by the machine operator to detect the unique code 1 1c of the spool Y before performing the operation for adhesive bonding between the two spools at speed. This information is loaded into the software of the control apparatus 6 in order to allow rapid synchronization of the reading of the unique code 1 1c. The system for detecting the unique code is installed on a motorized guide 13 provided with a sensor 14 for detecting the edge of the material. This system ensures the reading repeatability of the sensor 4.

By virtue of the information sent by the apparatus 6, which can comprise the processing speed of the machine detected by an encoder and the unique codes detected by the sensors (in particular the numbers of the two spools), the processing unit 5 is capable of updating the information related to the new obtained spool.

Optionally, the system according to the present invention comprises a label printer 9. These labels comprise a bar code 9a, which stores one or more of the following information items: production code of a product obtained from the processing of the material 10, a numeric identifier of the product, the number of unique codes printed for the product. This label can be applied to a spool and be read by a scanning apparatus 8 configured to read said bar codes 9a. This scanning apparatus 8 can be connected to the apparatus 6.

In Figure 5, the reference numeral 130 designates a server on which software is installed which has the function of associating the data related to the printing defects acquired by the system with a unique number that is related to the manufactured spool. Each produced spool can therefore have a (unique) reference code which is printed on the label affixed to its surface. On each production machine there is a scanning apparatus 8 for reading the code written on the label placed on the spool and acquire the data directly from the server 130. These data items of the spools manufactured and processed on the printing machines are then rendered available to the laminators and extruders for additional processing steps, in which other defects can be introduced and to the slitter and doctor machine to complete processing (cutting and removal of defects).

The net 12 is a net that is adapted to interconnect the various components 2, 4, 5, 6 of the system according to the present invention.

Figure 2 shows an embodiment of the unique code that can be printed on a portion of material.

Figure 3 shows a flowchart which illustrates the operation of the system of Figure 1.

In step 20, the inspection device 2 inspects the material (for example a ribbon of plastic material that can be wound on a support so as to obtain a spool of material), subjected to a processing step and signals any detected defects.

In step 21 , substantially simultaneously with the preceding step, the marking device 3 prints on the various portions 10a- lOd of the material a respective unique code 1 la-1 lc. In step 22 and after the printing of a unique code 1 1c, the detection device 4 reads the freshly printed unique code and sends this detection to the control apparatus 6.

If a defect on the material is signaled by the inspection device 2, step 23, in step 24 the processing unit 5 stores a control information item that is adapted to identify as defective the portion of material 10c that is associated with the unique code 1 1c detected substantially simultaneously with the signal.

In step 25, the spool of material is arranged on a machine designed to remove defects.

In step 26, the apparatus 6 locates the defective spool portions on the basis of the control information, for example by referencing a file made available by the processing unit 5.

In step 27, the apparatus 6 controls this machine so as to allow the removal of said defective portion.

It has thus been shown that the described method and system achieve the intended aim and objects. In particular it has been shown that the system thus conceived allows to overcome the qualitative limitations of the background art by means of a complete system for defect detection and tracing that covers the various processing steps, from the printing process to the intermediate steps up to the product finishing process. The system allows to identify within each individual printed spool the position of the defects and to stop automatically the slitter-rewinder only where the defect is present in order to be able to remove it from the original printed ribbon so that it is not delivered to the end user. The absolute traceability of the defects detected during the printing process allows total control of the quality of the product, since it is possible to identify, in the spool screening step, the position (XY) of the defects within the spools or sheets being processed with an advantageously millimeter precision. The system can be applied to any printing method, for example methods that use machines of the rotary, flexographic, offset, digital types and the like.

Clearly, numerous modifications are evident and can be performed promptly by the person skilled in the art without abandoning the protective scope of the present invention.

For example, the operation of the various components of the system can be implemented by means of modules of a computer program.

Preferably, the processing unit 5 runs software code that is designed to process all the received data and to manage a data bank.

Furthermore, if there is no need to detect defects in an intermediate processing step, the apparatus 6 can be configured to check only that the spools introduced in the machine and intended for the intermediate process actually correspond to the ones related to the production order.

Additionally, the apparatus 6 can be connected to an electronic keypad that allows an operator to indicate manually the detected defects and their position.

Therefore, the scope of the protection of the claims must not be limited by the illustrations or preferred embodiments shown in the description by way of example, but rather the claims must comprise all the characteristics of patentable novelty that reside in the present invention, including all the characteristics that would be treated as equivalents by the person skilled in the art.

The disclosures in Italian Patent Application no. 102015000088255 (UB2015A009538), from which this application claims priority, are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A system (1) for detecting and tracing defects during the steps for processing materials, particularly spools or sheets of material obtainable by printing, comprising:

- an inspection device (2), provided with means adapted to detect and signal one or more defects on a material (10);

- a marking device (3), adapted to print on said material (10) a plurality of unique codes (1 1a, l ib, 1 1c, l id), each one of said codes (1 1a, l ib, 1 1c, l id) being uniquely associated with a respective portion (10a, 10b, 10c, lOd) of said material (10);

- a detection device (4) adapted to read at last one of said codes (1 1a, l ib, 1 1c, l id) and to generate a data item related to the position of said portion (10a, 10b, 10c, l Od) of material associated with said at least one read unique code (1 1a, l ib, 1 1c, l id);

wherein the system (1) further comprises:

- a processing unit (5), configured to receive and correlate the signals generated by said inspection device (2) and the data generated by said detection device (4); said processing unit (5) being moreover configured to generate, based on said correlation, a control information item adapted to indicate the position of one or more of said portions (10a, 10b, 10c, l Od) containing a defect; said control information item being stored in a data bank comprised in said processing unit (5) and;

- a control apparatus (6) adapted to access said control information item and to locate, by means of said control information item, a portion (10a, 10b, 10c, lOd) of material containing a defect; said control apparatus (6) being further adapted to control a machine preset to remove said portion (10a, 10b, 10c, lOd) of material containing a defect.

2. The system according to claim 1, characterized in that it further comprises a positioning device (13) provided with a sensor (14) for detecting the edge of the material (10) for the arrangement of the marking device (3) and of the detection device (4).

3. The system according to claim 1 or 2, characterized in that said marking device (3) comprises a printer of the ink-jet type and said detection device (4) comprises an area camera.

4. The system according at least one of the preceding claims, characterized in that said control apparatus (6) comprises at least one sensor (7) adapted to read at least one of said codes (1 1a, l ib, 1 1c, l id) and means for interconnecting with at least one inspection device (2).

5. The system according to at least one of the preceding claims, characterized in that each one of said codes (1 1a, l ib, 1 1c, l id) comprises one or more of the following information items: identifier of the type of production step, an identifier of the material (10), the position of the portion (10a, 10b, 10c, lOd) of the material containing a defect associated with each one of said codes (1 1a, 1 lb, 1 1c, l id).

6. The system according to at least one of the preceding claims, characterized in that it comprises a label printer (9); said label printer (9) being adapted to print labels comprising bar codes (9a) that can be affixed on a product obtained by the processing of said material (10); said bar codes (9a) encoding one or more of the following information items: a production code, a numeric identifier of said product, the number of unique codes printed for said product; the system comprising moreover a scanning apparatus (8), preferably connectable to said control apparatus (6) adapted to read said bar codes (9a).

7. The system according to at least one of the preceding claims, characterized in that said material (10) is a ribbon comprising a plurality of printed codes (1 1a, 1 lb, 1 1 c, l id), each one associated with a portion (10a, 10b, 10c, lOd) of said ribbon; said position information being given by a value equal to the distance between the point where the respective code (1 1a, l ib, 1 1 c, 1 Id) is printed and the initial portion of said ribbon.

8. The system according to at least one of the preceding claims, characterized in that said marking device (3) is configured to print said codes (1 1a, l ib, 1 1c, 1 Id) on said material (10) at regular intervals, termed printing pitches, so that two codes (1 1c, l id) printed in succession are spaced by a distance equal to said interval.

9. The system according to at least one of the preceding claims, characterized in that said control apparatus (6) is adapted to be applied to machines designed to print said material (10), for example machines of the rotary, flexographic, offset, digital type.

10. The system according to at least one of the preceding claims, characterized in that said control apparatus (6) is adapted to be applied to machines adapted to process said material ( 10), for example machines such as a spreader, laminator, extruder or doctor rewinder; said control apparatus (6) being adapted to generate an information item, termed second control information item, adapted to locate a production defect on said material (10) caused by said machine; said second information item being given by an inspection device (2) comprised in said control apparatus (6) or by a data item entered by an operator assigned to controlling said machines adapted to process said material (10); said processing unit (5) being adapted to update said database with said second information item.

1 1. A method for detecting and tracing defects during the steps for processing materials, particularly spools or sheets of material obtainable by printing, comprising the steps of:

- inspecting (20) a material (10) subjected to a processing step and signaling defects detected on said inspected material (10);

- printing (21 ), substantially simultaneously with the inspection step, on said material a plurality of unique codes (1 1 a, l ib, 1 1c, l id), each one of said unique codes (1 1a, l ib, 1 1c, l id) being uniquely associated with a portion (10a, 10b, 10c, lOd) of said material (10); the printing of said unique codes (1 1a, l ib, 1 1c, l id) being performed preferably at regular intervals; - following the printing of one of said unique codes (1 1c), detecting said printed unique code (1 1c), and;

- in the event of the signaling (23) of a defect on a portion of material (10c), storing (24) a control information item adapted to identify as defective the portion of material (10c) associated with the unique code (1 1c) detected substantially simultaneously with said signaling;

- arranging (25) said material on a machine designed to remove said portion of material ( 10c) containing a defect;

- locating (26) the position of at least one portion of material (10c) containing a defect on the basis of said control information; and

- controlling said machine so as to allow the removal of said at least one portion of material (10c) containing a defect located by means of said control information.

12. The method according to the preceding claim, characterized in that said processing step comprises winding said material (10) on a spool; said arrangement step comprising arranging said spool on said machine; said control step comprises unwinding said spool and stopping the unwinding of said spool at said portion (10c) of material containing a defect so as to allow its removal.

13. The method according to at least one of the preceding claims 10 to 1 1 , characterized in that said control step comprises replacing a portion

(10c) of material containing a defect with another portion of material that is equivalent and has no defects.

14. A computer program stored on an electronic medium adapted to implement by means of code of the software type the steps of inspecting, printing, reading, storing, locating and controlling according to at least one of the preceding method claims 1 1 to 13.