Corrugated board production line and method equipped with cameras for detecting corrugated board accumulation

Abstract

A corrugated board production line is described, comprising at least one corrugator and a double-facer. A feed bridge is arranged between the corrugator and the double-facer, feeding single-faced corrugated board from the corrugator toward the double-facer. A camera captures at least a portion of the feed bridge. Single-faced corrugated board accumulates on the feed bridge in the form of loops moving along the feed bridge. The amount of corrugated board accumulated is a function of the number of loops on the feed bridge, and therefore a function of the position of the loop at the foremost position along the feed bridge in the feeding direction from the corrugator to the double-facer. Information about the foremost position of the accumulated material, and therefore about the amount of single-faced corrugated board found on the feed bridge, can be obtained from the images captured by the camera.

Description

Technical Field

[0001] This invention relates to corrugated cardboard production equipment. Background Technology

[0002] Corrugated board is manufactured from a flat web supplied from a corresponding master roll. Corrugated board typically comprises at least one layer of corrugated paper and two layers of flat paper (also called face paper), with the corrugated paper layer positioned between the two flat paper layers. The face paper is bonded to the corrugated paper layer at the crests of the corrugations. Generally, corrugated board may include more than one layer of corrugated paper. Typically, a flat paper separator layer is inserted between each pair of corrugated paper layers.

[0003] Production equipment or lines for producing corrugated board sheets typically include one or more unwinders for flat sheet continuous web rolls and one or more corrugators. Each corrugator converts the flat sheet continuous web into a corrugated sheet continuous web and joins the corrugated sheet continuous web to the flat sheet (i.e., the face sheet) continuous web. The composite continuous web thus obtained at the output of the corrugator is fed to a double-facer, where it is joined to a second face sheet. Generally, a production line may include one or more corrugators to feed one or more webs consisting of continuous corrugated sheets and face sheets to the double-facer. The production line also includes a section for processing the corrugated board from the double-facer, often referred to as the dry end to distinguish it from the section (wet end) that includes the machine from the unwinder to the double-facer. The dry end section typically includes a slitting and crimping station that cuts the corrugated board web into continuous longitudinal strips.

[0004] The continuous longitudinal strips are then further processed to produce a series of individual cardboard sheets, or fan-shaped folded strips, which are strips folded in a Z-shape according to the transverse creases and fold lines.

[0005] WO2017 / 036685 discloses a corrugated board production equipment equipped with multiple cameras suitable for detecting defects on corrugated board during production.

[0006] JP2019188501 discloses another type of corrugated cardboard production equipment, which has a camera along the last part of the production line, in which cross-cut individual corrugated cardboard sheets are pushed.

[0007] US2004 / 089394 discloses a production apparatus for producing corrugated board. This known production apparatus includes a complex system for calculating the amount of corrugated board accumulated on the bridge between a corrugating machine and a double-facer. The system includes nozzles for spraying water onto the corrugated board at predetermined points and a humidity sensor for detecting where moisture is present in the corrugated board. The humidity sensor, in combination with a photodetector, is used to calculate the amount of corrugated board accumulated on the bridge. This system for determining the amount of accumulated board is complex and inaccurate.

[0008] US576663 discloses another system for detecting the accumulation of corrugated board on the bridge of a corrugated board production equipment. This system also relies on the use of a photoelectric detector and is complex and inaccurate.

[0009] In various technical fields, US2016 / 018544 and US5970274 describe machines in which individual sheets are transported along a path, within which means are provided to control the proper feeding of the sheets based on the passage of the leading or trailing edge of each individual sheet. The failure of the leading or trailing edge of a sheet to pass is interpreted as an indication that the sheet has become stuck along the feeding path.

[0010] US2005 / 073082 discloses a machine for processing individual printed sheets in various technical fields, which includes a waste accumulation system with sensors for detecting the presence of waste.

[0011] Despite numerous improvements made to production equipment used to produce corrugated cardboard to enhance its performance and reduce production defects, downtime, or slowdowns, there are still some key aspects that can lead to production losses. Summary of the Invention

[0012] According to a first aspect, this document discloses a corrugated board production line, which comprises: a corrugating machine, the corrugating machine including: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; a pressure member for bonding the first paper web corrugated by the first corrugating roll and the second corrugating roll to a second flat paper web to form single-faced corrugated board; a first paper feeder for feeding the first paper web to the corrugating machine; a second paper feeder for feeding the second flat paper web to the corrugating machine; a double-facer; and a third flat paper feeder. A third paper unwinder is fed to the double-facer, and the third flattened paper web is glued to the single-faced corrugated board on the double-facer; a feed bridge extends between the corrugator and the double-facer; a first camera is located above the feed bridge and captures continuous webs of single-faced corrugated board along the feed path of the feed bridge; and an image processing unit is adapted to process the image captured by the camera located above the feed bridge and calculate the amount of single-faced corrugated board accumulated on the feed bridge based on the content of the image.

[0013] This production line configuration allows for continuous inspection of the stock level on the bridge. After establishing the maximum and minimum permissible stock levels, the speeds of the machines upstream and downstream of the bridge can be adjusted based on the stock level obtained by processing images captured by cameras, thereby reducing or increasing the stock level. For example, if the stock level drops below the minimum permissible value, the speed of the corrugating machine can be increased, and / or the feeding speed of the cardboard along the double-facer and downstream of it can be decreased.

[0014] According to another aspect, this document discloses a method for controlling the accumulation of single-faced corrugated board on a feed bridge of a double-facer in a corrugated board production line, wherein at least one camera connected to an image processing unit is associated with the feed bridge; the method includes the steps of: supplying single-faced corrugated board from the corrugator to the feed bridge; forming an accumulation of single-faced corrugated board on the feed bridge; capturing the portion of the feed bridge where the single-faced corrugated board accumulation is located using the camera; and obtaining information about the amount of single-faced corrugated board accumulation on the feed bridge from a series of images captured by the camera.

[0015] According to another aspect, this document discloses a corrugated board production line, which comprises: a corrugating machine, the corrugating machine including: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; a pressure member for bonding the first paper web corrugated by the first corrugating roll and the second corrugating roll to a second flat paper web to form single-faced corrugated board; a first unwinding machine for feeding the first paper web to the corrugating machine; a second unwinding machine for feeding the second paper web to the corrugating machine; a double-facer; and a third unwinding machine for feeding a third flat paper web to the double-facer. The third sheet is bonded to the single-faced corrugated board on the double-facer; a bridge extending between the corrugator and the double-facer; a cross-cutting machine; a basket positioned downstream of the cross-cutting machine and adapted to collect cut material removed from the corrugated board by cross-cutting performed by the cross-cutting machine; a camera positioned to capture at least a portion of the basket located downstream of the cross-cutting machine; and an image processing unit adapted to process the image captured by the camera and determine, based on the image, the extent to which the basket is filled with corrugated board cut material accumulated in the basket.

[0016] By analyzing the images captured by the camera, it is possible to verify when the material basket needs to be emptied or replaced. To this end, the control unit can generate alarms and / or messages to be sent to the operator via a suitable interface, which may be composed of or include mobile devices, such as smartphones or tablets.

[0017] This interface can also be used to provide information and / or alarms in cases where the accumulation of cardboard on the bridge decreases or increases excessively, the accumulation of which can be determined as described above by a camera set up for this purpose.

[0018] According to another aspect, this article describes a method for detecting the filling level of a crate for accumulating corrugated board cut material downstream of a cross-cutting machine in a corrugated board production line; wherein the method includes the steps of: capturing an image of the crate by a camera; and obtaining a matrix from the image captured by the camera, in which the vertical edges of objects contained in the image are highlighted.

[0019] According to another aspect, this document describes a corrugated board production line, which collectively includes: a corrugating machine comprising: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; a pressure member for bonding the first paper web corrugated by the first and second corrugating rolls to a second flat paper web to form a single-faced corrugated board; a first unwinding machine for feeding the first paper web to the corrugating machine; a second unwinding machine for feeding the second paper web to the corrugating machine; a double-facer; a third unwinding machine for feeding a third flat paper web to the double-facer, the third paper web being bonded to the single-faced corrugated board on the double-facer; a bridge extending between the corrugating machine and the double-facer; a first camera located at a critical location where corrugated board jamming occurs and configured to capture an image of the passing corrugated board; and an image processing unit adapted to process the image captured by the camera located at the critical location and adapted to determine, based on the content of the image, the occurrence of a jamming condition along a path advancing along a continuous corrugated board web. As will become clear later, the system described herein allows for the detection of jamming conditions in areas where continuous corrugated sheet webs are present, which may be continuous single-faced corrugated sheet webs (i.e., comprising a single flat face sheet bonded to a single corrugated sheet web) or continuous composite corrugated sheet webs (i.e., comprising two flat face sheets and at least one corrugated sheet web between the face sheets).

[0020] By processing images captured by one or more cameras located at one or more key locations, congestion can be identified in a timely manner, thus providing information and / or alarms to the operator. This can be done via an interface, which may be the same as the interface mentioned above used to indicate anomalies in the material baskets for collecting cut materials and / or anomalies in the accumulation of cardboard on the bridge.

[0021] According to another aspect, this article describes a method for detecting jamming conditions in a corrugated board production line, the method comprising the steps of: capturing an image of corrugated board passing along the production line; and processing the image to extract information indicating that a jamming condition of the corrugated board has occurred.

[0022] Further advantageous embodiments and features of the methods and production lines described herein are shown below and defined in the appended claims. Attached Figure Description

[0023] The invention will be better understood from the following description and accompanying drawings, which illustrate non-limiting exemplary embodiments of the invention. More specifically, in the drawings:

[0024] Figure 1(A) , 1(B) Figures 1(C) and 1(D) show successive portions of a corrugated board production equipment or production line arranged sequentially along the board feeding path;

[0025] Figure 2 Show Figure 1(A)-1(D) An enlarged view of the feed bridge on the production line used to feed single-faced corrugated cardboard to the double-facer;

[0026] Figure 3 , 4 Images 5, 6, 7, and 8 illustrate the process used to determine the accumulation of single-faced corrugated cardboard on the bridge of the double-facer;

[0027] Figures 9 to 19 Images illustrating the process of controlling jamming are shown; and

[0028] Figures 20 to 28 The image illustrates the process of controlling the filling level of the basket used to collect cut materials. Detailed Implementation

[0029] The detailed description of the exemplary embodiments set forth below is given with reference to the accompanying drawings. The same reference numerals in different drawings denote the same or similar elements. Furthermore, the drawings are not necessarily drawn to scale. The detailed description set forth below does not limit the invention. Rather, the scope of the invention is defined by the appended claims.

[0030] The references to "an embodiment," "this embodiment," or "some embodiments" in the specification mean that a particular feature, structure, or element described with respect to an embodiment is included in at least one embodiment of the described subject matter. Therefore, the phrases "in an embodiment," "in this embodiment," or "in some embodiments" used in the specification do not necessarily refer to the same one or more embodiments. Furthermore, the particular feature, structure, or element may be combined in any suitable manner in one or more embodiments.

[0031] The illustrated embodiment describes a production equipment or production line for producing double-walled corrugated board sheets, which are two corrugated sheets inserted between two flat sheets (or facing sheets) and a flat sheet inserted between the two corrugated sheets. Furthermore, the production line is configured to produce two stacks of board sheets on two adjacent stacker cranes.

[0032] However, it must be understood that the features described below can also be used in production equipment that has a different number of corrugating machines and is therefore suitable for producing corrugated board webs comprising different numbers of sheets or widths. Stacking systems can also vary, for example, to form single stacks or stacks of more than two sheets of board.

[0033] Similarly, the duplexer and slitting crimping station described below as examples can be configured in ways different from those described and shown herein.

[0034] Referring to the accompanying drawings, the production line includes: a first section 3 for producing a first single-faced corrugated board web, a second section 5 for producing a second single-faced corrugated board web, and a third section 7 for feeding two single-faced corrugated board webs and a flat sheet web to a double-facer 8 in section 9, said section 9 including said double-facer 8 and related accessories. Composite corrugated board is fed from section 9, wherein the composite corrugated board is assembled from a single-faced corrugated board web and another flat sheet web, said flat sheet web being bonded to the single-faced corrugated board web to form the second face of the composite corrugated board web.

[0035] Downstream of section 9 is section 11, in which a device for removing cut material is positioned. Downstream of section 11 is section 13, which is used to slit and crimp the continuous corrugated board web from section 9, which includes the double-facer 8, to divide the corrugated board web into multiple longitudinal strips and to form crimps along the longitudinal extensions of each longitudinal strip of the continuous corrugated board. Section 13 is also referred to below as slit and crimper 13.

[0036] The slitting and creasing section 13 may include a slitting cutter 13A and a creasing tool 13B, which are briefly and schematically shown in Figure 1(C). The slitting cutter 13A may include one or more rotating blade assemblies that engage with a fixed-fitting blade or a rotating-fitting blade, the blade and the fitting blade being positioned above and below the path of the composite corrugated board web CC, respectively. The blade and the fitting blade are adjustable laterally in the feed direction F of the composite corrugated board web CC to divide the composite corrugated board web CC into two or more longitudinal strips S1, S2, which are then cut into individual pieces by cross-cutting. In addition to dividing the composite corrugated board web CC into individual longitudinal strips, the slitting cutter is also used to produce side trimmings, which typically contain defective edge areas of the composite corrugated board web and are discarded.

[0037] The creasing tool may include a rotating creasing tool positioned above and below the path of the composite corrugated board web CC and producing longitudinal creasing lines thereon, the longitudinal creasing lines forming fold lines of the composite corrugated board sheet produced by transversely cutting strips of the composite corrugated board CC formed by a longitudinal cutter.

[0038] A suction nozzle 14 is positioned downstream of the slitting blade to remove the side cut material generated by the slitting blade.

[0039] In the illustrated embodiment, the production line or production equipment 1, as an example, further includes: a cross-cutting section 15 for cutting corrugated cardboard strips S1, S2 from section 13; a dual conveyor 17 having two series of conveyors 17A, 17B that transport cardboard sheets Fc to corresponding stackers; and finally, two stackers or stacking areas, indicated by 19A and 19B, for forming stacks P1, P2 of cardboard sheets cross-cut in section 15 and fed by the dual conveyors 17 (17A, 17B).

[0040] In some embodiments, a single conveyor 17 and a single stacker crane 19 may be provided.

[0041] The first corrugating machine 21 is arranged in section 3. Corrugating machines capable of producing single-faced corrugated board webs are known. The main components of the corrugating machine will be described below, and the corrugating machine can be manufactured, for example, as described in US 78714223 or EP 1362691.

[0042] In short, the corrugating machine 21 may include a first corrugating roll 23, which cooperates with a second corrugating roll 25 and a pressure roll 27 or other pressure member to join the flat paper web and the corrugated paper web together, as described below. The first flat paper web N1 is fed to the corrugating machine 21 from a first unwinder 29. The unwinder 29 can be manufactured in known ways and will not be described in detail. The unwinder 29 may include two positions for a first paper roll B1 and a second paper roll B1X, from which the first paper roll B1 is being unwound and the first flat paper web N1 is fed, while the second paper roll B1X is ready and will be unwound when the paper roll B1 is exhausted.

[0043] The second flattened paper web N2 is unwound from the second unwinder 31, which may be substantially the same as the unwinder 29, and on which the first paper roll B2 and the second paper roll B2X to be used may be arranged. The paper web N2 is unwound from the first paper roll B2, while the second paper roll B2X will begin to be unwound when the paper roll B2 is exhausted.

[0044] The first flattened paper web N1 is fed to the corrugated roll 23 after passing over the heating roll 33. The winding arc of the flattened paper web N1 around the heating roll 33 can be changed to transfer a larger or smaller amount of heat from inside the heating roll 33 to the flattened paper web N1, which is heated, for example, by steam circulating therein.

[0045] The first flattened paper web N1 is corrugated by passing through the gap formed by corrugating rolls 23 and 25. Corrugated paper web N1 is thus obtained at the exit of the gap between corrugating rolls 23 and 25. Using the glue applicator 35, suitable glue is applied to the corrugations formed on the thus obtained corrugated paper web, allowing corrugated paper web N1 to adhere to the flattened paper web N2, which, together with the corrugated paper web N1, is fed through the gap formed between the second corrugating roll 25 and the pressure roll 27.

[0046] The glue application assembly 35 may include a glue applicator roller 36 that contacts the flutes of the corrugated paper web N1 driven around the second corrugated roller 25. The glue applicator roller 36 receives glue from a dispensing roller or anilox roller 38, which picks up glue from a groove 40 or other glue source. The distance between rollers 36 and 38 can be adjusted to regulate the amount of glue applied to the corrugated paper web N1.

[0047] In some embodiments, the second flattened paper web N2 may be fed around one or more rolls 37, 39 arranged between the unwinder 31 and the corrugator 21 for heating. The contact arc between the flattened paper web N2 and one or both of the rolls 37, 39 can be altered to change the heat transferred from one or more of the rolls 37, 39 to the flattened paper web N2 before it contacts the pressure roll 27. The pressure roll 27 can also be internally heated to perform bonding between the paper webs N1 and N2 under high pressure and high temperature conditions.

[0048] like Figure 2 As shown in the enlarged view, a single-faced corrugated board web NS, formed by a first corrugated web N1 and a second flat web N2, is obtained at the exit of the corrugator 21. The flutes or flute peaks O formed on the first web N1 are bonded to the surface of the flat web N2 facing the corrugated web N1 by means of adhesive C applied to the flutes O by the adhesive applicator 35.

[0049] A bridge 41 is positioned downstream of the corrugator 21, extending toward section 5 of the production line 1 and subsequently sections 7 and 9. Accumulated material S of single-face corrugated cardboard webs NS can be formed on the bridge 41 by forming suitable accumulation loops or loops, allowing the operating speed of the corrugator 21 to be at least partially independent of the operating speeds of the downstream sections.

[0050] The single-faced corrugated board web NS is then fed to the heating roller 43 along a first path extending above the bridge 41. The single-faced corrugated board web NS is able to be wound around the heating roller in an adjustable arc to be properly heated before reaching the double-facer 8 in section 9.

[0051] In the illustrated embodiment, production line 1 includes a second section 5, substantially identical to section 3, in which a second single-faced corrugated board web, again designated NS, is formed by passing through another pair of paper webs N4, N5 from the same paper unwinders 29 and 31, and a corrugator identical to corrugator 21. This is fed to bridge 41 to form a stockpile S, and then wound around a heating roll 45 substantially identical to heating roll 43 before being fed to the double-facer 8 in section 9.

[0052] In other embodiments, section 5 and the corresponding corrugator may be omitted. Conversely, in still other embodiments, more than two sections 3, 5, and associated corrugators and unwinders of the paper webs may be provided to form corresponding single-faced corrugated paper webs NS, which are then joined together by gluing using the double-facer 8 of section 9.

[0053] The flattened paper web N3 is unwound from another unwinder 47, preferably bypassing the heated roller 49, and fed to the double-facer section 9. In a known manner, the glue application assemblies 51, 53 apply glue to the flutes of the respective corrugated paper webs in the two single-faced corrugated paper webs NS to bond them together and to the flattened paper web N3, which will form the second outer sheet of the composite corrugated paperboard CC fed from section 9, the first outer sheet being formed from the flattened paper web N2.

[0054] Section 9, which includes the duplexer, can be manufactured in a known manner and will not be described in detail herein. Examples of embodiments of the duplexer are disclosed in US 7.291.243 and US 2012 / 0193026, and further details regarding the manufacture of this production line section can be found in those documents.

[0055] A cross-cutting machine 61 is arranged in section 11, which is capable of performing cross-cutting to completely or only partially cut the composite corrugated cardboard CC fed from section 9. The cross-cutting machine 61 can be manufactured, for example, as described in US 6,722,243. As will be described in more detail below, the cross-cutting machine 61 is particularly capable of discarding portions of the corrugated cardboard CC that have adhesive defects or other defects.

[0056] The composite corrugated cardboard CC fed through the slit creasing section 13 is divided into longitudinal strips S1 and S2, which are capable of turning along two paths defined by the two conveyors 17A and 17B of section 17. Section 13 can be manufactured in a known manner, for example as described in US 5.951.454, US 6.165.117, US 6.092.452, US 6.684.749, US 8.342.068 or other prior art documents cited in the aforementioned patent documents.

[0057] Two conveyors 17A and 17B transport corrugated cardboard sheets Fc, which are obtained in section 15 by cross-cutting continuous strips S1 and S2 of composite corrugated cardboard CC. Conveyors 17A and 17B unload the cardboard sheets onto stackers 19A and 19B to form stacks P1 and P2 on stacking platforms 63 and 65, which are known and can be manufactured, for example, as described in EP 1710183, US5,829,951, or other patent documents cited therein.

[0058] Reference numeral 62 indicates a cross-cutting station that cross-cuts continuous strips S1, S2 of composite corrugated cardboard CC from the slit creasing section 13. In the illustrated embodiment, the cross-cutting station 62 includes stacked cross-cutters 62A, 62B that cut each continuous strip from section 13 into individual cardboard sheets of a given length. In this exemplary embodiment, two cross-cutters 62A, 62B are provided, positioned at two different levels, because the production line 1 operates on two levels, and two conveyors 17A, 17B that feed the cardboard sheets Fc to two stackers 19A, 19B are positioned on said two levels. If a single stacker 19 is provided, a single cross-cutter may be sufficient.

[0059] Folding members 64A and 64B are positioned between each cross-cutting machine 62A, 62B and the associated conveyors 17A, 17B. These folding members are adapted to arrange individual sheets Fc of composite corrugated board CC in a folded arrangement on the conveyors 17A, 17B, i.e., the sheets Fc partially overlap each other, as particularly shown in Figure 1(D). The folding members 64A and 64B may include conveyors that slow the feeding of the sheets Fc and top brushes that, in combination with the conveyors below, cause partial overlap of the sheets Fc of the composite corrugated board obtained by cross-cutting the individual longitudinal strips S1, S2.

[0060] The corrugated cardboard sheets Fc are fed to stacker cranes 19A and 19B by two conveyors 17A and 17B (each of which can be formed by a series of individual belt conveyors connected in series). Unloading components 20A and 20B are arranged at the exit ends of conveyors 17A and 17B, each of which can include a corresponding upper roller that mates with the corresponding lower end of conveyor 17A and 17B.

[0061] In the production line or production equipment 1 described above, there are some key aspects for controlling the proper operation of the production line.

[0062] The first key aspect relates to the formation and maintenance of the proper accumulation of single-faced corrugated board NS on bridge 41, or, if production line 1 has more than one bridge, on each bridge 41. The accumulation of single-faced corrugated board NS on the bridge 41 of the production line, or on each bridge 41, can be used, for example, in the step of splicing paper webs from a depleted roll to a new roll ready for use. To ensure the proper operation of the entire production line, it is advantageous, in fact, that during this transitional splicing step, the speed of the web downstream of the point where splicing occurs remains approximately constant, while in the splicing zone, the feed rate of the web to be spliced ​​is temporarily stopped.

[0063] Maintaining a basic uniformity of feed for single-faced and composite corrugated board along and downstream of the double-facer is important, for example, to ensure uniform heating of the paper web around the rolls or other heating elements and along the double-facer 8. For instance, slowing down the paper web on the double-facer 8 can cause overheating, leading to bonding defects or damage to the paper web. This is because the thermal inertia of the double-facer 8 and the heating rolls (e.g., rolls 43, 45, 49) does not allow for sufficiently rapid temperature adjustment to accommodate changes in the amount of corrugated board passing through per unit time.

[0064] Therefore, in certain situations and environments, it is important to verify the presence of sufficient single-faced corrugated board (NS) stock on bridge 41 before beginning the splicing operation from a depleted roll to a new roll. This stock can vary over time and, for example, gradually increase as the splicing step approaches. The need to perform splicing can be predicted based on the diameter of one or more rolls, or in some cases, by continuously measuring the length of the unwound web since the last splicing operation.

[0065] To determine (at least at the fill percentage level of bridge 41) the amount of single-faced corrugated cardboard NS present on bridge 41, or on each bridge 41, a camera system comprising one or more cameras positioned above each bridge 41 can be used. In the illustrated embodiment, Figure 1(A) and 1(B) The camera 101 is positioned at the midpoint of each bridge 41. The camera 101 can be a single unit. In some cases, multiple cameras may be arranged side-by-side along the direction transverse to the feed direction (arrow F) of the single-faced corrugated cardboard NS on the bridge 41.

[0066] As shown in the attached diagram, especially Figure 2 As shown, the camera is oriented backward, meaning it captures the corrugated cardboard web that is advancing along bridge 41 and approaching camera 101. The camera has an inclined optical axis that forms an angle of less than 90°, for example, less than 45°, with the direction of advancement of the corrugated cardboard.

[0067] In some embodiments, a system with a plurality of cameras may be provided, the plurality of cameras being distributed along the longitudinal extension of the bridge 41, i.e., along direction F, or a system with a plurality of camera assemblies may be provided, the cameras of each assembly being aligned with each other in the lateral direction, and each individual assembly being spaced apart from each other in direction F.

[0068] The camera 101 associated with bridge 41, or each camera, can be connected to control unit 100 (FIG. 1(B)), which can be programmed to perform the image processing procedures described below. Alternatively, the camera 101, or each camera 101, can be equipped with its own computing resources that process the images captured by the camera and send data related to the processing results to control unit 100.

[0069] Therefore, generally, each camera is associated with an image processing unit. This could be a control unit 100 that receives and processes images captured by one or more cameras 101. In this case, the control unit represents the image processing unit for one or more cameras on a production line. Alternatively, each camera 101 may have its own image processing unit that processes the images captured by the camera. In this case, data, signals, or commands obtained by processing images on the cameras can be sent to the control unit 100.

[0070] In other embodiments, there may be intermediate solutions, such as one or more processing units that process images captured by one or more cameras, processing the images to output data that is transmitted to control unit 100. If necessary, this data can be further processed by control unit 100. Therefore, in this case, image processing can be performed in different steps by means of different processing units that can be performed in series.

[0071] The instructions provided herein regarding one or more cameras 101 associated with bridge 41, and regarding the distribution of computing resources for processing the corresponding images captured by the cameras, also apply to the remaining cameras that production line 1 can set up, which will be described in more detail below.

[0072] The control unit 100 can be connected to one or more human-machine interfaces (HMIs). Figure 1(B) shows two interfaces 102 and 104, for example, for inputting data and instructions and for displaying information or notifications. In some embodiments, the control unit 100 can be connected to a mobile unit, such as a smartphone, laptop, tablet, or other peripheral device, generally indicated by 106, and can be provided to personnel responsible for supervising and managing production line 1.

[0073] Generally, the accumulated material S on bridge 41 begins to form at the point where single-faced corrugated board NS from the corresponding corrugator 21 is unloaded onto bridge 41 from its guide roller 103 or other feeding member. The accumulated material S moves along the feeding direction F and occupies a length Ls of bridge 41. The accumulated material S is formed by overlapping loops or loops of single-faced corrugated board NS. Each loop or loop is approximately identical to the others. Therefore, the length Ls of the section of bridge 41 occupied by the accumulated material S of single-faced corrugated board NS provides quantitative data about the length of the available single-faced corrugated board web NS in the accumulated material S. The longer the length Ls, the greater the accumulation. This can be expressed as a percentage relative to the total length between the minimum and maximum accumulation positions.

[0074] Figure 2 An enlarged side view of the portion of bridge 41 on which the accumulated material S is formed is shown. MAX and MIN indicate the maximum and minimum accumulation points, i.e., the maximum and minimum allowable accumulation amounts on the bridge. The MIN point represents the point where the accumulation amount is at the minimum allowable value (which can be equal to zero). Camera 101 is positioned above bridge 41 to capture the entire length of the bridge between the MAX and MIN points. Figure 3 The image shown is captured by camera 101 when the accumulated material S is between the MAX point and the MIN point.

[0075] To determine the amount of single-faced corrugated cardboard NS available in the stock of material S as a percentage relative to the corresponding minimum and maximum quantities, the following reference can be used. Figures 3 to 9 The specific process described describes how to process images captured by camera 101 or each camera 101.

[0076] First refer to Figure 3 The process first captures a continuous image of the area taken by camera 101, and identifies four points on it that define the line of minimum accumulation (i.e., minimum accumulation amount) and the line of maximum accumulation (i.e., maximum accumulation amount).

[0077] Each captured image is converted to grayscale, so that the brightness level (i.e. the intensity of the pixel) is associated with each pixel.

[0078] Since the single-faced corrugated board web NS is moving, the area of ​​the extended single-faced corrugated board NS can be identified by obtaining the difference between consecutive images (i.e., consecutive frames captured by camera 101 and converted into grayscale images). This area is where the loops or loops forming the accumulating material S extend, creating the extended portion of the single-faced corrugated board NS. The extended corrugated board areas appear substantially the same in the consecutive images, while in areas where accumulating loops or loops exist, the consecutive images differ from one another due to the feeding movement of these loops or loops.

[0079] Therefore, by subtracting two consecutive frames or images previously converted to grayscale, the area of ​​the stretched single-faced corrugated cardboard NS will appear darker because each pixel in that area has the same intensity in the two images subtracted from each other. Conversely, areas with accumulating loops or loops of NS will appear brighter because the intensity of individual pixels changes over time due to movement. This also applies to the edges of the single-faced corrugated cardboard NS downstream of the accumulating material S, because the single-faced corrugated cardboard NS has irregularities along its edges, meaning that corresponding pixels in two consecutive frames will not have the same brightness.

[0080] It is important to note that the two frames subtracted from each other are not necessarily adjacent, but rather spaced apart in time by an interval greater than the acquisition interval. Each frame is considered a pixel matrix. The image obtained from the difference is... Figure 4 As shown in the figure. In essence, it has bright pixels that tend to be white in the area where the single-faced corrugated cardboard NS transitions from the accumulated form (the loop of the accumulated material S) to the stretched form, and along the edge (i.e. in the area where the cardboard vibrates).

[0081] Figure 4 The image is further processed to identify the line along which the foremost ring of corrugated cardboard is arranged (i.e., the most downstream ring along the feeding direction of the cardboard), because this line is the line that defines the area of ​​accumulated material S along the bridge.

[0082] Therefore, according to the embodiments described herein, the following can be performed.

[0083] In subsequent processing steps, a threshold is applied to all values ​​of the matrix represented by the image's pixels to transition from an integer-valued matrix (grayscale) to a binary matrix, which is a matrix composed of black and white pixels. This black and white image... Figure 5 As shown in the diagram. Subsequently, the region with the highest white pixel density in the search matrix is ​​identified.

[0084] Therefore, basic operators for processing matrices can be applied to black-and-white binary matrices. The first applicable operator is the "dilation" operator, which gradually expands (increases) the white area. This operator allows for the expansion of objects in the image, filling small gaps, and connecting objects separated by distances smaller than the size of the structuring element used by the operator. In the example shown in this paper, the dilation operator is applied using a structuring operator of an appropriate size in pixels (from...). Figure 5 (Image begins) Figure 6 The results are shown in the image.

[0085] An erosion operator is applied to the new image; in a binary image, this operator erodes the outline of white regions. This operation is repeated several times while maintaining the size of the matrix containing the operator's structuring elements. Figure 6 The image begins to obtain the result in Figure 7As shown in the image. In fact, it has been derived from a grayscale image ( Figure 4 The image was obtained. Figure 7 ),exist Figure 7 A single white line appears in the image, positioned at the boundary between the extended single-faced corrugated cardboard NS downstream of the stock material S and the stock material S itself. Figure 4 In the grayscale image, the oscillating regions of the single-sided corrugated cardboard NS are identified by gray pixels. Essentially, Figure 7 The white line is the starting point of the accumulated material S.

[0086] The percentage of accumulated material on bridge 41 is determined by the relative position of the white line obtained from the process with respect to the maximum and minimum accumulation positions, as described above. Figure 8 It is clearly shown in the text.

[0087] In short, by processing the images obtained by camera 101, the percentage amount of accumulated material S relative to the minimum and maximum accumulated values ​​is obtained.

[0088] If a single camera 101 is insufficient to generate an image of the entire area between the minimum and maximum accumulation values ​​of the accumulated material S, a pair of cameras arranged sequentially along the bridge can be used, and the images from the two cameras can be combined to produce a single pixel matrix, which is the sum of two pixel matrices representing the two images, which are simultaneous in time but spatially spaced along the longitudinal extension of the bridge 41 (the extension along the feeding direction of the single-faced corrugated cardboard NS). The maximum and minimum accumulation lines will be found in the image obtained from the sum of two partial images captured by the two successive cameras, one of which contains the minimum accumulation line and the other contains the maximum accumulation line.

[0089] Another key aspect of managing production line 1 described above is the possibility of paper jamming (or clogging) at various points on the production line. For this purpose, one or more cameras can be used, arranged to capture key areas of the path of the paper web, or the continuous or segmented path of single-faced corrugated board NS or composite corrugated board CC.

[0090] Typically, one or more cameras can be installed in the following areas or locations on production line 1:

[0091] - At the entrance and / or exit of the cross-cutting machine 61, cameras 103 and 105 are indicated respectively, see Figure 1(C);

[0092] - At the nozzle 14, there is an indication of a camera 107, see Figure 1(C);

[0093] - At the inlet and outlet of the longitudinal cutting pressure assembly 13, see cameras 109 and 111 in Figure 1(C);

[0094] - At the shingled components 64A and 64B, see cameras 113A and 113B in Figure 1(D); and

[0095] - At stacker cranes 19A and 19B, see cameras 115A and 115B in Figure 1(D).

[0096] Additional cameras, not shown, can be positioned, for example, in the middle area or location of the slitting and creasing assembly, between pairs of cutters arranged sequentially along the feeding direction of the corrugated cardboard.

[0097] It must be understood that the list indicated above is an example, and additional cameras can be deployed at other key points on production line 1. In some embodiments, fewer cameras than are listed may also be installed.

[0098] These cameras can also be connected to control unit 100, which can be programmed to perform the image processing described below. Alternatively, one, some, or each camera can be equipped with its own computing resources that process the images captured by the camera and send data related to the processing results to control unit 100.

[0099] The images captured by these cameras are processed to detect the possibility of jamming of paper or cardboard in the area captured by the cameras. The purpose of analyzing the images captured by the cameras is to detect whether and where the paper (in the form of paper web, or single-faced corrugated board NS or composite corrugated board CC) exhibits behavior different from normal movement, which corresponds to a jamming condition.

[0100] The image processing method is configured such that by examining the images (frames) captured successively by the respective cameras, it can be verified whether the web (paper or cardboard) is undergoing deformation or change that may cause jamming.

[0101] The following text refers to Figures 9 to 19 An embodiment of the algorithm is described. Each image captured by a camera (e.g., camera 105 mounted downstream of cross-cutting machine 61) is converted into a grayscale image and treated as a matrix of rows and columns, where each element of the matrix is ​​represented by the intensity of the corresponding pixel of the image.

[0102] Select M rows and N columns that are equidistant from each other in the matrix. Figure 9The matrix is ​​schematically represented (for representational purposes, it has an exemplary number of elements that are far fewer than the number of pixels that actually form the image), highlighting three (M=3) rows R1, R2, R3 of the elements of the matrix that will be considered for subsequent processing operations. Figure 10 The same matrix is ​​schematically represented, highlighting the four (N=4) columns C1, C2, C3, C4 of the matrix whose elements will be considered for subsequent processing operations.

[0103] The first step of the processing method is to generate a vector V of length mp for each row. M , where m is the number of elements in the row, and p is an arbitrarily chosen integer, typically between 1 and 20, for example between 2 and 10, preferably between 4 and 6. Vector V M The i-th element is given by the absolute value of the difference between the value of the i-th element and the value of the (i+p)-th element in the starting row Rj, such as... Figure 11 The diagram illustrates this. The method is repeated for the M rows selected in the initial matrix, thereby obtaining a vector of length (mp) for each of the selected M rows, the elements of which are given by the absolute values ​​of the intensity differences of the starting pixels.

[0104] Then, each vector V M The vector is reordered in descending order of the values ​​of each of its elements. The reordered vector is represented in this paper as... The first element of a vector is the element with the highest value, and the last element is the element with the lowest value. For each vector... Extract the value at position T starting from the highest value, where T is an integer chosen in a suitable manner, for example, between 5 and 30, preferably between 8 and 15, such as between 9 and 11. Rearrange the vector. The value of the Tth element and the threshold Th M Compare them.

[0105] Apply the same process to the selected N columns to obtain vector V. N Then transform it into a vector that is reordered according to the decreasing values ​​of its elements, using... Represented. Each element at position S (where S can be equal to or different from T, but chosen according to similar criteria) is associated with a threshold Th. N The threshold Th is compared. N It can be equal to or different from the threshold Th M .

[0106] In short, the process generates a series of M+N values ​​for each image, where each value is compared with a threshold (the threshold may be equal or different for the M values ​​obtained from M rows and for the N values ​​obtained from N columns).

[0107] Essentially, the criteria described above highlight changes in the images captured by the camera that occur in cases of corrugated cardboard deformation, which may precede jamming. The described algorithm prevents false jamming alarms when isolated defects (such as splice lines, markings, or other artifacts that are not signs of the onset of corrugated cardboard jamming) pass in front of the camera. Conversely, gradual deformation on relatively large surfaces of the corrugated cardboard (which typically leads to jamming) is identified by the algorithm because it is reflected in the rearrangement vector. and Among multiple values ​​that exceed the threshold.

[0108] The jam alarm is generated based on how many out of N+M values ​​exceed a corresponding threshold. To make this process more robust against false alarms, advantageously, it is only generated if a certain number (or all) of the M values ​​calculated for M rows exceed the corresponding threshold Th. M Furthermore, if a certain number (or all) of the N values ​​calculated from N columns exceed the corresponding threshold Th N Only then will a jamming signal be generated.

[0109] To better understand the process described, Figures 12 to 19 Two real-world scenarios are shown, in which a camera captures an area of ​​production line 1 (e.g., upstream of the cross-cutting machine 61). Figure 12 The image shown is captured by camera 103 under normal operating conditions (i.e., without jamming). The image, now converted to grayscale, shows two areas of different intensities of the pixels that form it, due to the presence of shadows cast onto the corrugated cardboard. Figure 13 A grid consisting of three rows and seven columns of pixels is shown on the same image. Figure 12 Show one of these columns, Figure 14 The processing shown in the example involves this column. It must be understood that... Figure 13 The pixels in the remaining rows and columns represented by the grid shown in the diagram undergo similar processing.

[0110] Figure 14 This shows how to generate vector V starting from the selected column of pixels. N Steps A, B, and C, and the generated vector Steps (in) Figure 14 It is located at position D). For practical reasons, Figure 14 Only a portion of the pixel column is shown, therefore only the corresponding vector V is shown. N and Part of it.

[0111] More specifically, in Figure 14In the vector, position A indicates a portion of the column of pixels under consideration. Position B indicates a portion of the same column offset by four positions (in this case, the value "p" indicated above is p=4). The number indicated in a single element of the vector is the intensity of a single pixel. Position C indicates a (partial) vector V formed by the differences in intensity values. N Therefore, (partial) vector V N The first element is equal to 80 - 40 = 40. The vector at position D is a rearranged vector. The first element has a value of 120, which is V. N The maximum value contained in it. The last element has a value of 0, which is V. N The minimum value contained in it. The value at position S is related to the threshold Th. N The value being compared. In this case, the value is 40.

[0112] Figures 16 to 19 The sequence shows that... Figures 12 to 15 The images are from the same sequence, but the captured images show a situation where the cardboard is stuck. (As from...) Figure 19 As can be observed, vectors The S-th position of (the vector in D) has a value of 80 instead of 40. A threshold for comparison with the value at the S-th position is chosen so that... Figures 12 to 15 In situations where no alarm is triggered, but... Figures 16 to 19 This situation triggered an alarm.

[0113] from Figures 12 to 19 The images clearly show that the process described above allows for the generation of jamming alarm signals by processing images captured by the camera. As mentioned, for greater robustness and insensitivity to noise, alarm signals can be generated when more than one rearranged vector in the considered row or column vectors has a value greater than a threshold at position T or S.

[0114] Another key aspect of the operation of production line 1 is the need to accumulate and remove the cross-cut and discarded portions of the composite corrugated cardboard CC, for example, upstream of the slitting creasing section 13. More precisely, this type of cut material is formed by the cross-cutting machine 61. The cut material can be collected by setting up a basket 93, in which the cut material CD generated by the cross-cutting performed by the cross-cutting machine 61 is accumulated.

[0115] To ensure the proper operation of the entire production line or production equipment 1, it is recommended to first check that the material basket 93 is present and correctly positioned at the exit of the cross-cutting machine 61. Additionally, it is recommended to check the fill level of the material basket 93, i.e., the amount of discarded cardboard pieces accumulated in the basket 93, to ensure that the cut material CD is collected correctly, thereby preventing subsequent cut material from falling to the ground if the basket is completely full. By checking the fill level of the material basket 93, notifications can be provided to the operator, such as notifications to empty the basket or replace it with an empty basket.

[0116] For this purpose, a camera 120 can be installed in the area of ​​the basket 93 to capture the basket 93 from the front or side. The images captured by the camera 120 can be processed to: (a) detect the presence or absence of the basket 93; and (b) detect the amount of accumulated corrugated cardboard cut material CD, thereby detecting the filling degree of the basket.

[0117] In a particularly efficient embodiment, the camera 120 is positioned laterally relative to the basket 93, although it is shown in a frontal position in the figures only for clarity.

[0118] The lateral capture of basket 93, i.e., the view corresponding to the view shown in Figure 1(C), allows for more efficient observation, as will be clear from the following description of the method for processing the captured images.

[0119] The captured image was converted into a grayscale image. Figure 12 The image shown is a grayscale representation of a basket 93, partially filled with cardboard cut material placed at the bottom. The image can be cropped to fit the side area containing the cart, and then the following processing method is applied to the side area.

[0120] A vertical Gaussian blur filter is applied to the captured image. This filter acts on each pixel of the image, setting its value to the average of all values ​​of pixels existing in a defined neighborhood of the pixel being considered. The filter is defined as "vertical" because the neighborhood of the pixel being considered is much larger in the vertical direction than in the horizontal direction.

[0121] An edge detection filter is applied to the image obtained by applying a vertical Gaussian blur filter. This edge detection filter produces a new black-and-white image, essentially forming a binary matrix where each pixel represents an element of the matrix, and each element can take two values ​​corresponding to black and white in the obtained image. In other words, the result of applying two filters is a black-and-white image, i.e., a binary matrix, in which the vertical edges of visible objects in the image are highlighted. Figure 21 , 22 Images 23 and 24 show three of these images obtained for three different filling levels of basket 93. Figure 21The image corresponds to an actually empty basket. Figure 22 The image corresponds to the middle padding, while Figure 23 The image corresponds to a basket that is actually full.

[0122] The next step is to apply the "dilation" operator followed by the "erosion" operator to the resulting binary matrix in order to connect the broken lines to each other, reduce noise, and improve the clarity of the edges. Figure 24 , 25 Figures 26 and 26 show how to apply expansion and corrosion operators... Figure 21 , 22 The results were obtained from images 23 and 23.

[0123] To estimate the fill level of basket 93, the method can at this point include another image processing step, from which a single column vector is obtained, containing an element equal to the number of rows in the previously processed image. Each element of the column vector is obtained by calculating the average of each row of the image. In other words, the j-th element of the column vector has a value that is the average of the values ​​of the N elements in the j-th row of the image. The column vector thus obtained is traversed from top to bottom, ignoring the initial values ​​corresponding to black pixels. The first white pixel encountered indicates the upper part of basket 93. The last white pixel in the series indicates the level of cardboard in the basket. The last element of the column vector (i.e., the lowest element) indicates the bottom of the basket. The fill percentage of the basket is calculated based on these data.

[0124] Figure 27 and 28 The instructions respectively indicate: the binary image or matrix obtained after applying the dilation and erosion operators when the basket is filled to 20%; and the corresponding column vectors.

[0125] The presence or absence of the material basket 93 can be detected using the same camera 120. For this purpose, the material basket can be marked, and the mark is captured by the camera 120 when the material basket 93 is correctly positioned. The images captured by the camera 120 can be processed to verify whether the mark exists in the position it should be in when the material basket 93 is in the correct position.

[0126] The systems of the described type can interface with a local IT network that allows monitoring of one or more production lines within the same or several production facilities. Production lines equipped with the aforementioned camera systems can also be connected to remote control units, for example, via a communication portal. Alarm signals, diagnostic messages, or other information obtained from the data processed as described above can also be transmitted via email, SMS, or other messaging systems to local or remote computers, or to mobile devices such as mobile phones or tablets.

[0127] After describing various aspects of the corrugated cardboard production line, the innovative aspects of this specification are summarized as follows:

[0128] Clause 1. A corrugated cardboard production line, comprising:

[0129] A corrugating machine, comprising: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; and a pressure member for bonding the first paper web corrugated by the first corrugating roll and the second corrugating roll to a second flat paper web to form a single-faced corrugated board.

[0130] A first paper ejector for feeding the first paper web to the first paper ejector of the corrugating machine;

[0131] The second paper ejector is used to feed the second flattened paper web to the second paper ejector of the corrugating machine;

[0132] Double-sided machine;

[0133] A third paper feeder is used to feed a third flat sheet to the double-facer, the third flat sheet being glued to the single-faced corrugated board on the double-facer;

[0134] A feeding bridge extending between the corrugating machine and the duplexing machine;

[0135] A first camera, positioned above the feeding bridge, captures images of the single-sided corrugated cardboard along its feeding path.

[0136] An image processing unit is provided, which is adapted to process images captured by the camera located above the feed bridge and to calculate the amount of single-sided corrugated cardboard accumulated on the feed bridge based on the content of the images.

[0137] Clause 2. The production line according to Clause 1, wherein the image processing unit is configured to identify the position of the single-faced corrugated cardboard stack material in loop form moving along the feed bridge on an image captured by the camera.

[0138] Clause 3. The production line according to Clause 2, wherein the image processing unit is configured to determine the position of the single-faced corrugated board stack on the feed bridge by subtracting successive images to obtain a difference image from the image captured by the first camera, and by identifying a line on the difference image corresponding to the front end of the single-faced corrugated board stack.

[0139] Clause 4. A method for controlling the accumulation of single-faced corrugated board on a feed bridge of a double-facer in a corrugated board production line, wherein at least one camera connected to an image processing unit is associated with the feed bridge; wherein the method includes the following steps:

[0140] Single-faced corrugated cardboard is supplied from the corrugating machine to the feeding bridge;

[0141] Single-sided corrugated cardboard is accumulated on the supply bridge;

[0142] The camera is used to capture the section of the supply bridge where the single-sided corrugated cardboard is stored.

[0143] Information about the amount of single-faced corrugated cardboard accumulated on the feed bridge is obtained from continuous images captured by the camera.

[0144] Clause 5. The method according to Clause 4, wherein the step of forming a single-faced corrugated board accumulation on the feed bridge includes the step of forming a series of accumulated loops of single-faced corrugated board from the inlet of the feed bridge toward the outlet of the feed bridge.

[0145] Clause 6. The method according to Clause 5, wherein the step of obtaining information about the amount of single-faced corrugated cardboard accumulated on the feed bridge includes the step of identifying the position of the front end of the series of accumulated loops on the feed bridge.

[0146] Clause 7. The method according to Clause 6, wherein the step of identifying the position of the front end of the series of cumulative loops comprises the steps of converting consecutive images captured by the camera into binary matrices, and subtracting two binary matrices corresponding to two consecutive images captured by the camera from each other to obtain a difference matrix.

[0147] Clause 8. The method according to Clause 7 further includes the step of applying one or more operators to the difference matrix to identify lines on the difference matrix corresponding to the positions of the front ends of a series of loops accumulated on the supply bridge.

[0148] Clause 9. The method according to Clause 8, wherein the operator includes an expansion operator and an erosion operator.

[0149] Clause 10. A corrugated cardboard production line, comprising, in combination:

[0150] A corrugating machine, comprising: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; and a pressure member for bonding the first paper web corrugated by the first corrugating roll and the second corrugating roll to a second flat paper web to form a single-faced corrugated board.

[0151] Used to feed the first paper web to the first paper ejector of the corrugating machine;

[0152] The second paper ejector is used to feed the second paper web to the second paper ejector of the corrugating machine;

[0153] Double-sided machine;

[0154] A third paper feeder is used to feed a third flattened paper web to a double-facer, where the third paper web is glued to a single-faced corrugated board on the double-facer.

[0155] A bridge extending between the corrugating machine and the double-facer;

[0156] Cross-cutting machine;

[0157] A material basket, which can be positioned downstream of the cross-cutting machine and is adapted to collect the cut material removed from the corrugated cardboard by the cross-cutting performed by the cross-cutting machine;

[0158] A camera, positioned to capture at least a portion of a basket located downstream of the cross-cutting machine; and

[0159] An image processing unit is provided, which is adapted to process images captured by a camera and determine, based on the images, the extent to which the basket is filled with corrugated cardboard cut material accumulated in the basket.

[0160] Clause 11. The production line according to Clause 10, wherein the image processing unit is configured to obtain a matrix from an image captured by a camera, in which the vertical edges of objects contained in the image are highlighted.

[0161] Clause 12. The production line according to Clause 11, wherein the image processing unit is configured to convert an image captured by a camera into a grayscale image and obtain the matrix from the grayscale image.

[0162] Clause 13. The production line as described in Clause 10 or 11, wherein the matrix is ​​a binary matrix.

[0163] Clause 14. The production line according to Clause 11, 12 or 13, wherein the image processing unit is configured to obtain a vector from the matrix, the value of which indicates the filling degree of the basket.

[0164] Clause 15. The production line according to any one of Clauses 10 to 14, wherein the camera is positioned to laterally capture a basket based on a line of sight orthogonal to the corrugated cardboard along the feed direction of the production line.

[0165] Clause 16. A method for detecting the fill level of a basket for accumulating corrugated board cut material downstream of a cross-cutting machine in a corrugated board production line; wherein the method comprises the following steps:

[0166] Capture images of the material basket using a camera; and

[0167] A matrix is ​​obtained from the image captured by the camera, in which the vertical edges of objects contained in the image are highlighted.

[0168] Clause 17. The method according to Clause 16 includes the step of converting the image into a grayscale image before obtaining the matrix from the image captured by the camera.

[0169] Clause 18. The method according to Clause 16 or 17, wherein the matrix is ​​a binary matrix.

[0170] Clause 19. The method according to Clause 16, 17, or 18, wherein the step of obtaining the matrix includes the following steps:

[0171] A vertical Gaussian blur filter is applied to the image detected by the camera, and the image is first converted to grayscale if necessary; and

[0172] An edge detection filter is then applied to the image.

[0173] Clause 20. The method described in Clause 19 further includes the following steps after applying the edge detection filter:

[0174] Apply the expansion operator to the matrix; and

[0175] The erosion operator is then applied to the matrix.

[0176] Clause 21. The method according to any one of Clauses 16 to 20, comprising the step of obtaining a vector from the matrix, wherein the value of the vector indicates the degree of filling of the basket.

[0177] Clause 22. The method according to any one of Clauses 16 to 21 includes the step of verifying the presence of the basket based on an image captured by a camera.

[0178] Clause 23. The method described in Clause 22, wherein the presence of the basket is verified based on the presence of a mark applied to the basket.

[0179] Clause 24. The method according to any one of Clauses 16 to 23, wherein the camera is positioned to laterally capture a basket based on a line of sight orthogonal to the feeding direction of the corrugated cardboard along the production line.

[0180] Clause 25. The method according to any one of Clauses 16 to 24 includes the step of generating a request to replace or empty the basket when it is detected by processing an image captured by a camera that the basket's filling level has reached a limit.

[0181] Clause 26. A corrugated cardboard production line, comprising, in combination:

[0182] A corrugating machine, comprising: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; and a pressure member for bonding the first paper web corrugated by the first corrugating roll and the second corrugating roll to a second flat paper web to form a single-faced corrugated board.

[0183] Used to feed the first paper web to the first paper ejector of the corrugating machine;

[0184] The second paper ejector is used to feed the second paper web to the second paper ejector of the corrugating machine;

[0185] Double-sided machine;

[0186] A third paper feeder is used to feed a third flattened paper web to a double-facer, where the third paper web is glued to a single-faced corrugated board on the double-facer.

[0187] A bridge extending between the corrugating machine and the double-facer;

[0188] A first camera, located at a critical position where the corrugated cardboard jams, is configured to capture images of the passing corrugated cardboard; and

[0189] An image processing unit is adapted to process images captured by a camera located at the key location and to determine the occurrence of a jamming condition based on the content of the images.

[0190] Clause 27. The production line according to Clause 26, wherein the critical location is one or more of the following: the inlet of the cross cutter; the outlet of the cross cutter; the inlet of the suction nozzle for longitudinal cutting material for corrugated board; the location upstream or downstream of the creasing tool; the location upstream or downstream of the slitting cutter; the location adjacent to the folding member; the location adjacent to the stacker.

[0191] Clause 28. The production line according to Clause 26 or 27, wherein the processing unit is configured to: extract multiple vectors corresponding to a series of rows and a series of columns of a matrix, the elements of which consist of pixel intensities of an image captured by a camera or a portion thereof; process the values ​​of individual vectors to extract information indicating anomalous changes in pixel intensity along the corresponding vector.

[0192] Clause 29. The production line according to Clause 28, wherein the processing unit is configured to: obtain a difference vector for each vector, the elements of the difference vector consisting of the absolute value of the difference between the intensities of two successive but non-adjacent pixels of the vector; sort each difference vector in ascending order of the values ​​of its elements and obtain sorted difference vectors; compare the elements at predetermined positions of each sorted difference vector with a threshold; and generate a jam notification if, for a predetermined number of the sorted difference vectors, the number of elements compared with the threshold exceeds the threshold.

[0193] Clause 30. A method for detecting jamming conditions in a corrugated cardboard production line, the method comprising the following steps:

[0194] Capture images of corrugated cardboard passing along the production line;

[0195] The image is processed to extract information indicating that a jamming condition has occurred in the corrugated cardboard.

[0196] Clause 31. The method according to Clause 30, wherein the step of processing the image includes the following steps:

[0197] Extract multiple vectors corresponding to a series of rows and columns from the matrix, wherein the elements of the matrix consist of pixel intensities of an image captured by the camera or a portion thereof; and

[0198] Process the values ​​of a single vector to extract information indicating anomalous changes in pixel intensity along the corresponding vector.

[0199] Clause 32. The method according to Clause 31, wherein the step of processing the value of a single vector includes the following steps:

[0200] For each vector, a difference vector is obtained, the elements of which consist of the absolute values ​​of the differences in intensity between two successive but non-adjacent pixels of the vector;

[0201] Sort each difference vector in ascending order of the values ​​of its elements, and obtain the sorted difference vector;

[0202] The elements at predetermined positions of each sorted difference vector are compared with a threshold; and if, for a predetermined number of the sorted difference vectors, the number of elements compared with the threshold exceeds the threshold, a jam notification is generated.

[0203] Clause 33. The method according to any one of Clauses 30 to 32, wherein images are captured at one or more of the following locations: upstream of the cross cutter; downstream of the cross cutter; a suction nozzle near the longitudinal cutter of the corrugated board; upstream of the creasing tool; downstream of the creasing tool; upstream of the slitting cutter; downstream of the slitting cutter; at the folding member; and at the stacker.

Claims

1. A corrugated cardboard production line, comprising: A corrugating machine, comprising: a first corrugating roll and a second corrugating roll that cooperate with each other to corrugate a first paper web; and a pressure member for bonding the first paper web corrugated by the first corrugating roll and the second corrugating roll to a second flat paper web to form a single-faced corrugated board. A first paper ejector for feeding the first paper web to the first paper ejector of the corrugating machine; The second paper ejector is used to feed the second flattened paper web to the second paper ejector of the corrugating machine; Double-sided machine; A third paper feeder is used to feed a third flat sheet to the double-facer, the third flat sheet being glued to the single-faced corrugated board on the double-facer; A feeding bridge extending between the corrugating machine and the duplexing machine; A first camera, positioned above the feeding bridge, captures images of the single-sided corrugated cardboard along its feeding path. An image processing unit is adapted to process images captured by the first camera located above the feed bridge and to calculate the amount of single-sided corrugated cardboard accumulated on the feed bridge based on the content of the images.

2. The corrugated board production line according to claim 1, wherein the image processing unit is configured to identify the position of single-faced corrugated board stock in the form of loops or loops moving along the feed bridge on an image captured by the first camera.

3. The corrugated cardboard production line according to claim 2, wherein the image processing unit is configured to position the foremost loop or loop between the minimum accumulation position and the minimum accumulation position along the feeding direction of the corrugated cardboard on the feeding bridge.

4. The corrugated board production line according to claim 2 or 3, wherein the image processing unit is configured to determine the position of the single-faced corrugated board stock on the feed bridge by subtracting consecutive images to obtain a difference image in the image captured by the first camera, and by identifying a line corresponding to the front end of the single-faced corrugated board stock on the difference image.

5. A method for controlling the accumulation of single-faced corrugated board on a feed bridge of a double-facer in a corrugated board production line, wherein at least one camera connected to an image processing unit is associated with the feed bridge; wherein the method includes the following steps: Single-faced corrugated cardboard is supplied from the corrugating machine to the feeding bridge; Single-sided corrugated cardboard is accumulated on the supply bridge; The camera is used to capture the section of the supply bridge where the single-sided corrugated cardboard is stored. as well as Information about the amount of single-faced corrugated cardboard accumulated on the feed bridge is obtained from continuous images captured by the camera.

6. The method of claim 5, wherein the step of forming a single-faced corrugated cardboard accumulation on the supply bridge comprises: The steps of forming a series of cumulative loops or loops of single-faced corrugated cardboard from the inlet of the feeding bridge toward the outlet of the feeding bridge.

7. The method of claim 6, wherein the step of obtaining information about the amount of single-faced corrugated cardboard accumulated on the supply bridge comprises: The step of identifying the position of the front end of the series of cumulative loops or rings on the supply bridge.

8. The method of claim 7, wherein the step of identifying the position of the front end of the series of accumulating loops or rings on the feed bridge comprises the step of positioning the foremost loop or ring between the minimum accumulation position and the maximum accumulation position along the direction of advancement of the corrugated cardboard on the feed bridge.

9. The method of claim 7 or 8, wherein the step of identifying the position of the leading edge of a series of cumulative loops or rings comprises the steps of converting consecutive images captured by the camera into binary matrices, and subtracting two binary matrices corresponding to two consecutive images captured by the camera from each other to obtain a difference matrix.

10. The method of claim 9, further comprising the step of: applying one or more operators to the difference matrix to identify lines on the difference matrix corresponding to the positions of the front ends of a series of loops or rings accumulated on the supply bridge.

11. The method of claim 10, wherein the operator comprises an expansion operator and an erosion operator.

Images