Method for operating a production line for the production and processing of sheets of corrugated cardboard, and production line

Abstract

A method for operating a production line (4) for the production and processing of sheets (8) of corrugated cardboard is described, wherein the production line (4) has a first station (6) in the form of a corrugated-cardboard installation (2), with which multiple sheets (8) are produced, wherein a stack (16) is formed from one or more of the sheets (8), wherein at least one production parameter (18) is determined for the sheets (8) of the stack (16) and is stored in a data record (20), which is assigned to the stack (16), wherein the production line (4) has at least one second station (6), to which the stack (16) is transferred for processing, wherein the data record (20) is stored in a control unit (22) which uses the production parameter (18) as a basis for controlling processing of the sheets (8) of the stack (16) by the second station (6).

Description

[0001] Description

[0002] Method for operating a production line for the manufacture and processing of corrugated board sheets and production line

[0003] The invention relates to a method for operating a production line for the manufacture and processing of sheets of corrugated cardboard and to a production line for carrying out such a method.

[0004] Corrugated board sheets are produced using a corrugator. The corrugator first combines several paper webs into a single corrugated board web and then assembles these into individual sheets (more precisely: corrugated board sheets). The sheets are then fed to one or more further stations, where they are printed, folded, or simply transported or stored. This results in a production chain, with the corrugator as the first station, followed by the subsequent stations. The sheets are then passed along the production chain from station to station.

[0005] The properties of the sheets produced depend on the one hand on the choice of appropriate values ​​for the operating parameters of the corrugator during operation (i.e. during sheet production), but on the other hand also on the properties of the paper webs from which the sheets are made. The properties of the paper web, the properties of the sheets at the end of the corrugator and the operating parameters of the corrugator during sheet production are each production parameters which ultimately determine the quality of the sheets and the products made from them. A particular problem is that the production parameters and thus the properties of the sheets vary regularly, meaning that subsequent stations may not process the sheets optimally. In general, it is therefore desirable to adjust each station as optimally as possible to the properties of the sheets, which vary depending on the production process.However, the stations downstream of the corrugator usually have no knowledge of the actual properties of the sheets and therefore cannot be optimally adjusted. In principle, it is conceivable that the sheet properties relevant to the respective station could be measured online, but this would be complex in terms of equipment.

[0006] DE 102014 205 674 A1 describes a material flow system that receives data on the current status of containers in the form of a file, which can be exchanged with units like an electronic container card. When a specific container enters the material flow control system, it is assigned to a specific order. Container-specific data is transmitted for material flow control. The data itself can be carried on a read / write memory, e.g., a transponder, by the container or a transport device. The material flow control system has access to data on pending orders, from production planning, and on the processing status of containers to be handled. Using this data, transport orders are generated and transmitted to transport devices.

[0007] Against this background, it is an object of the invention to provide an advantageous and / or improved method for operating a production line for the manufacture and processing of corrugated cardboard sheets, as well as a suitable production line for this purpose. In particular, the processing of the sheets and the resulting quality are to be improved.

[0008] The object is achieved according to the invention by a method having the features according to claim 1 and by a production line having the features according to claim 14. Advantageous embodiments, refinements, and variants are the subject of the dependent claims. The statements in connection with the method also apply mutatis mutandis to the production line, and vice versa. If steps of the method are specified implicitly or explicitly below, advantageous embodiments for the production line result from the fact that it is designed to carry out one or more of these steps. For this purpose, the production line has, in particular, a correspondingly designed control device.

[0009] The method is used to operate a production line for the manufacture and processing of corrugated board sheets. During operation of the production line, sheets are first manufactured and then further processed. The term "processing" is understood broadly here to mean "handling". Thus, processing includes not only the forming, reworking, or modification of the sheets, but also storage and transport. Preferably, however, the production line has at least one station apart from the corrugator for forming, reworking, or modification of the sheets; the production line therefore does more than just transport or store the sheets produced by the corrugator. The result of the processing is, for example, several packaging boxes, each of which is made from one of the sheets.The production line is then a production line for the manufacture of packaging boxes made of corrugated cardboard.

[0010] The production line has several stations. Specifically, the production line has a corrugator as a first station, which is used to produce several sheets. During sheet production, the corrugator first produces a corrugated board web from several paper webs, which are then cut into individual sheets. These sheets are deposited in particular in a stacker at the end of the corrugator and from there fed to a subsequent station. A stack is formed from one or more of the sheets, in particular in the stacker. Each stack thus contains at least one sheet, but typically several, preferably identical sheets. Overall, the corrugator is used to produce sheets one after the other, repeatedly and / or continuously, and to form stacks from these sheets, which are then output from the corrugator for further processing by one or more subsequent stations.

[0011] A production parameter is determined, in particular measured, for the sheets in the stack and stored in a data set which is assigned to the stack. The data set is assigned to the stack in particular while the stack is being formed or afterwards and then before or while the stack leaves the corrugator or is transferred to the next station. The production parameter is representative of the production of the sheets. In a preferred embodiment, the production parameter is determined while the sheets in the stack are being produced, so that the data set then contains a production parameter at the time the sheets are produced. An alternative embodiment is also suitable, in which the production parameter is determined at least in close temporal proximity (e.g. + / - 5 min) to the production of the sheets, in particular only when a stack is formed from the sheets.It is then assumed that the production parameter changes only slightly over time and can therefore be used with a reasonable approximation (e.g. + / - 10%) to correctly specify or derive a property of the sheets. If necessary, the production parameter is corrected based on a trend or on empirical values, e.g. using an offset. Several stacks which are produced with the same or approximately similar production parameters are also referred to as a batch. Optionally, the same data set is then used for an entire batch. Another suitable embodiment is in which the running time of the sheet from the point at which the production parameter is determined to its storage is simply measured for correct assignment. Preferably, several production parameters are determined and stored in the data set.The data set can therefore consist of a single manufacturing parameter or multiple manufacturing parameters. Optionally, the data set can also contain other parameters, such as order or customer data.

[0012] As the data passes through the production line downstream of the corrugator, it is advantageous to enrich the data set with additional data, such as time stamps and the type of subsequent processing. Alternatively or additionally, the previously determined production parameters are re-determined (i.e., their values ​​are measured) and updated.

[0013] The production parameter is, in particular, an operating parameter of the corrugated board system (e.g., machine, process, or control parameters) or a sheet parameter (e.g., product or material parameters of a sheet or a paper web used to produce it). The production parameter thus describes the production of the sheet and thus indirectly a property of the sheet or directly a property of the sheet itself. Preferably, as many such production parameters as possible are summarized in the data set in order to document the production of the sheets as comprehensively as possible for the most optimal control of subsequent stations.

[0014] The production parameter typically varies during the production of the sheets. In order to be able to take this variation into account during further processing, the production parameter is preferably determined repeatedly, i.e. its current value is determined and saved in a data set for later control of a downstream station. For each stack, the value of the production parameter is therefore determined at the time of production (or at least shortly thereafter) of the sheets in the stack and saved. It is initially sufficient if the value of the production parameter is determined for at least one sheet in the stack, or as an average value or similar across several sheets in the stack, or even as an average value or similar across several stacks. Initially, it is only important that the production parameter reflects the possible variation during production to a certain extent.In principle, however, a particularly precise design is also advantageous, in which the production parameter is determined and saved for each individual sheet, so that each sheet has its own data set. However, without loss of generality, it is assumed below that a stack has several sheets and that a single data set is assigned to the stack, so that all sheets in the stack are assigned the same data set and therefore also the same production parameter. The production line has at least one second station to which the stack is transferred for processing. The second station is located downstream of the corrugator. The second station typically processes the sheets in the stack individually one after the other, but simultaneous processing of several sheets or the entire stack is also possible.In the following, it is assumed, without loss of generality, that the production line has several additional stations in addition to the corrugator.

[0015] As part of the process, the data set is stored in a control unit, which controls the processing of the sheets in the stack by the second station depending on the production parameters. This allows further processing downstream of the corrugator to be adapted to the actual properties of the sheets due to potentially varying production. The data set is either generated outside the control unit and transferred to it, or generated within the control unit.

[0016] To ensure that the correct data set is transferred to the respective station that processes the assigned stack, the production line in particular has a tracking system for the stack. In particular, the production of a respective stack is reported to the tracking system by the corrugator machine, expediently when this stack is transferred to a conveyor belt, AGV (automated guided vehicle) or similar for further distribution in the production line. The tracking system then tracks the stack as it passes through the production line so that when it reaches a specific station, the data set assigned to the stack is actually used to control it. This means that the correct data set is always used when a stack is transferred to a respective station for control purposes.In particular, the tracking system also knows how the stack is transported and in what order it is transferred to which stations. The tracking system therefore assigns each stack, and thus each data record, a virtual position within the production line, so that the association between data record and stack is correctly maintained. The stack is physically transported through the production line, while the associated data record virtually moves with this stack. As soon as the stack is transferred to a specific station, the data record is also transferred to this station, or this station is at least controlled depending on the data record. Some advantageous configurations of the tracking system are explained in more detail below.

[0017] In summary, the process initially documents the production of the sheets in the data records for the stacks, and this information (i.e. the data records) is then used to optimally adapt the processing of the sheets in the stations downstream of the corrugator to the actual properties of the sheets. The board metadata determined during production, e.g. exact thickness, moisture content, adhesive content or other parameters and properties of the sheets, or material parameters derived from these, e.g. strength parameters, are passed on, i.e. transmitted, to a downstream station. The transfer is preferably via a suitable data interface and / or tracking of the stack along a transport path (tracking the logistics chain along which a particular stack passes through the production line). The entire transport path of the production line, including all sources, routes, and sinks, is expediently mapped.In other words, the production line knows which stack, or even which sheet, is located where and when within the production line. To achieve this, each individual stack is seamlessly tracked from the moment it is produced in the corrugator, e.g., using a camera system or transport logic that knows the sequence of stacks along a transport path through the production line and, for example, simply counts the stacks.

[0018] In principle, a physical element such as an ID tag, marking, QR code, barcode, RFID tag, etc. on the stack, the sheet, or on a means of transport (e.g., pallet or AGV) can serve as a type of digital routing slip. The physical element then contains the data record or refers to it within a central database. The physical element then physically moves with the stack, ensuring correct assignment of the data record to the stack. The physical element is then read at a respective station using a suitable reading device. The reading device is, for example, a barcode scanner, a camera, an RFID tag reader, or the like. In the present case, however, a preferred embodiment is one in which such a physical element is neither required nor used. Rather, the data record itself is preferably not a physical element, but merely a virtual element, i.e.Data which is stored in a control unit and can be transmitted along a suitable signal path (e.g. signal line or wirelessly). The data record is preferably stored separately from the stack, i.e. the data record is not physically connected to the stack. Alternatively or additionally, the data record is preferably transferred separately from the stack, i.e. the data record is not transferred via the same path as the stack. In a particularly preferred embodiment, the method described here does not require a separate physical element on the stack or sheet for the purpose of referring to the respective data record. The data record is then merely virtually "attached" to the stack and thus assigned to it. In particular, no persistent marking is applied to the stack itself.

[0019] A core aspect of the present invention is therefore the use and / or utilization of cardboard metadata for post-processing, i.e., the determination of production parameters (cardboard metadata) during sheet production and the transfer of these production parameters to subsequent stations so that these subsequent stations can be optimally configured for further processing (post-processing) of the sheets. Production line

[0020] The control unit is fundamentally a part of the production line and, depending on its design, controls one or more stations on the production line. In a suitable design, the control unit is part of the production line control device mentioned above for carrying out the method, or is even identical to it. There are basically two variants for the control unit: it can be either a central or a decentralized control unit. In the first variant, the control unit is a central control unit of the production line in which the data set is stored (centralized approach). The data sets for the various stacks are thus stored centrally in the control unit and then used by it to control the individual stations. The control unit is particularly aware of how a respective stack is to be transported by means of a logistics system (containing, for example,Conveyor belts, transport vehicles or similar) of the production line through the production line. For this purpose, the control unit is expediently connected to a logistics control unit of the logistics system or such a logistics control unit is integrated into the control unit; in the latter case, the control unit then takes over control of the logistics system itself. To control an individual station, either the relevant data set for the stack to be processed is passed from the control unit to the second station, e.g. to a sub-control unit of the second station, and the second station derives a suitable control command from the data set. Alternatively, the data set remains in the central control unit and this derives a suitable control command from the data set, which the control unit then uses to control the second station.In the first case, the control command is derived centrally (central intelligence), whereas in the second case, it is derived decentrally (decentralized intelligence). A combination is also possible (hybrid intelligence), in which at least one station receives the data set and derives the control command itself, and at least one other station receives the control command directly from the central control unit.

[0021] In the second variant, the data set is stored decentrally (decentralized approach). The control unit is then not a central control unit, but a decentralized control unit which is part of the second station and primarily or exclusively controls this second station. In particular, in the case of further stations, each of these further stations expediently also has its own control unit, so that the data set is then passed on to each of the stations in order to process the assigned stack accordingly as soon as it is passed on to the respective station. In principle, it is possible to pass the data set to several stations simultaneously after it has been created. In a preferred embodiment, however, the data set is passed from one station to the next station parallel to the stack and is thus passed on together with the stack.The data record is suitably only ever stored in the control unit of the station that will next process the assigned stack. The data record is therefore passed from station to station, analogous to the physical transfer of the stack from station to station. This ensures that the assignment between stack and data record is maintained as it passes through the production line. In principle, it is possible to implement this with a data carrier or an ID tag that is physically linked to the stack, e.g., attached to it or printed on it. In this case, however, a purely virtual link between the data record and the stack is preferred. In other words, the data record is only virtually assigned to the stack.This is made possible in particular by means of the tracking system, which continuously tracks the stack so that it is known at all times where the stack is located in the production line.

[0022] The central and decentralized storage of the data set can generally be combined, e.g. in such a way that the data set is stored both in a central control unit of the production line and at the same time decentralized in one or more stations, e.g. independently of the central control unit or based on it.

[0023] The stack is transported within the production line, in particular along a transport path from station to station. In a suitable embodiment, when the stack is transferred from one station to the next, the data record is also transferred from one station to the next along a data path. This embodiment is particularly suitable for a production line with one or more decentralized control units. The transport path is the path along which the stack is physically transported through the production line. The data path is in particular parallel (in a functional sense, not necessarily physically) to the transport path, but independent of it in that the data record is not physically attached to the stack, but merely virtual. The data path is the path along which the data record is transmitted to the respective stack.The data path expediently follows the transport path, at least virtually, to ensure that the assignment between stack and data record is maintained. However, this is not mandatory as long as the tracking system at least tracks the stack, so that at least its position along the transport path is known. However, when transferring the data record from station to station in the same way as the stack is transferred, a tracking system is unnecessary; the stack is simply tracked by the transport path. Since the data record is transferred in parallel, the assignment to the correct stack is inherently maintained. Central definition and knowledge of the transport path are advantageously not required. The data path may, for example, have a physical signal line from one station to the next, but a corresponding wireless connection is just as suitable.For example, corresponding interfaces or logical inputs and / or outputs of two stations of the production line (e.g. the corrugator and the second station) are connected to each other via a signal line.

[0024] The preceding station suitably has an output transport means and the following station a receiving transport means; both transport means are part of the transport path. The transport means are, for example, conveyor belts. When the stack is transferred from the output transport means to the receiving transport means, a presence sensor at the following station detects the transfer of the stack to this subsequent station, which then, in response, receives or requests the data set from the preceding station via the signal line (pull principle). An equivalent embodiment is one in which a presence sensor at the preceding station detects that the stack is leaving this preceding station and then also initiates the transmission of the data set to the following station (push principle). The presence sensor is, for example, a light barrier.Instead of the data record, control data or a reference to such data or a reference to the data record in a database can also be transmitted. In a suitable embodiment, the association between the data record and the stack is maintained as it passes through the production line because the stack is recognized and tracked by a camera system. The camera system is in particular part of the tracking system. The camera system has one or more cameras, each of which monitors one or more stations on the production line and, in doing so, recognizes and tracks the respective stacks. In order to recognize the stacks based on one or more images from a respective camera, the tracking system expediently has an image recognition unit, e.g. as part of the camera system.Each stack is first identified during production by the tracking system, particularly at the end of the corrugator, and the corresponding data set is assigned at this time. The stack then moves through the production line along a corresponding transport path and is continuously tracked by the camera system, ensuring that the correct data set is transferred upon transfer to one of the stations on the production line. For example, a combination with a warehouse is possible, which simply monitors the sequence of incoming and outgoing stacks, so that no tracking by the camera system is required within the warehouse to obtain (i.e., maintain) the assignment to the data set.

[0025] In a preferred embodiment, a contour of the stack is determined and the data set is assigned to this contour. This determination of the contour is also referred to as "stack shape recognition". The camera system already described is particularly suitable for this purpose. When the stack is transferred to the second station, the contour of the stack is (again) determined and then the data set assigned to this contour is used to control the second station. In other words: at the station, the contour of the stack and thus also the stack itself is recognized and then the correct data set is used to control this station. In this way, the use of a separate, physical element for recognizing (i.e. identifying) the stack is dispensed with; instead, the contour of the stack itself is used. The "contour" of a respective stack refers in particular to a circumferential line of the stack or a part, e.g.only one side of this circumference. The circumference is obtained, for example, by means of an edge detection method from an image generated by the camera system or by another suitable sensor unit. A sensor, e.g. the presence sensor already mentioned (e.g. as a line sensor), at the entrance to a respective station is also particularly suitable, so that the contour is automatically determined when the stack is transferred to the corresponding station. Since the contour can fundamentally change due to processing in a respective station, the contour is expediently determined again (i.e. updated) at the end of such a station.

[0026] As already described, at least one production parameter is determined for the sheets of the stack. This preferably occurs during the production of the sheets, alternatively while the stack is being formed from them. In any case, the production parameter is determined in the context of the production of the sheets and the stack. Suitably, the production parameter is determined by measuring it within the corrugated board plant, expediently with a sensor unit that is integrated into the corrugated board plant. The sensor unit is thus part of the corrugated board plant. In a suitable embodiment, the sensor unit is already present in order to measure the production parameter for controlling or monitoring the corrugated board plant. The sensor unit has, for example, an ultrasonic sensor for determining the strength, a laser triangulation sensor for determining the thickness, or an optical sensor, e.g.Camera for determining warp and / or defects. "Warp" refers specifically to the curvature of a sheet, which is typically due to differential stretching or shrinkage of the various paper layers of the corrugated board.

[0027] The manufacturing parameter is preferably one of the following manufacturing parameters, also referred to as sheet parameters:

[0028] - Thickness of a sheet

[0029] - Moisture of a bow - Warp of a bow

[0030] These production parameters are particularly relevant for a variety of potential further processing steps in stations downstream of the corrugator. For example, the warp is relevant if the second station has a number of suction cups for handling each sheet. Thickness is particularly relevant for the nip width of the second station's feed nip. Moisture is especially relevant for printing at the second station.

[0031] Other suitable manufacturing parameters that can be determined and used within the process are: a) Data on the history of the corrugated board web, the sheets or the paper from which the corrugated board web and thus also the sheets are made, e.g.

[0032] - Name of the manufacturer

[0033] - Place of manufacture

[0034] - Date of manufacture

[0035] - Storage time until next useA / processing

[0036] - Storage conditions (e.g. humidity and / or ambient temperature) until the next use / processing

[0037] - Transport time of the paper until the next use

[0038] - Transport conditions (e.g. humidity and / or temperature of the environment) b) Basic properties of the corrugated board web, the sheets or the paper from which the corrugated board web and thus also the sheets are made, e.g.

[0039] - Humidity / moisture content

[0040] - mass per unit area

[0041] - Thickness

[0042] - Ash content

[0043] - Fiber orientation (also fiber orientation angle) c) Tensile properties of the corrugated board web, the sheets or the paper from which the corrugated board web and thus also the sheets are made, e.g.

[0044] - Breaking force

[0045] - Tear length

[0046] - Elongation at break

[0047] - Modulus of elasticity d) Surface printability properties of the corrugated board web, the sheets or the paper from which the corrugated board web and thus also the sheets are made, e.g.

[0048] - Smoothness, e.g. according to Bekk

[0049] - Roughness, e.g. according to Bendtsen

[0050] - Air permeability, e.g. according to Bendtsen / Gurley e) Properties specifically of the corrugated board web and sheets (especially corrugated board base paper properties), e.g.

[0051] - Flat crush resistance (e.g. according to CMT = Concora Medium Test, FCT = Flat Crush Test or similar)

[0052] - Strip crush resistance (e.g. according to SCT = Short Crush Test)

[0053] The above list identifies suitable manufacturing parameters, but is not intended to be exhaustive. Using only a subset of the manufacturing parameters mentioned is already advantageous, but it is particularly useful to determine as many manufacturing parameters as possible and combine them in a data set for a respective batch.

[0054] The aforementioned production parameters are material or product parameters that directly characterize the sheets or the materials used to produce them. Alternatively or additionally, it is also expedient to determine and use one or more operating parameters of the corrugator, also known as machine parameters. Accordingly, in an advantageous embodiment, the production parameter is an operating parameter of a production line section of the corrugator. An operating parameter characterizes the state of the corrugator during the production of the sheets, i.e. the production conditions. Thus, an operating parameter does not characterize the product (the sheets) produced by the corrugator directly, but only indirectly, and is therefore expediently determined and used at least to derive one or more properties of the sheets.The production line part is, for example, an unwinder, a splicer, a gluing unit, a preheater, a single facer, a double facer, a printer, an applicator (e.g. for applying a varnish), a cross cutter, a cutting and creasing machine and the like, or an individual component of the corrugator, e.g. corrugating roller, heating roller, heating plate, spray bar, cutting knife and the like.

[0055] Suitable operating parameters are in particular the operating parameters listed below:

[0056] - Glue gap width in the gluing unit of the corrugator

[0057] - Amount of glue applied in the gluing unit of the corrugator

[0058] - Properties of the glue, e.g. type of starch used

[0059] - Amount of moisture applied by a spray bar, steam bar or similar device on the corrugator

[0060] - Temperature of a drying or heating element of the corrugator, e.g. heating roller of the preheater, heating plate, IR dryer, hot air dryer

[0061] - Volume flow of hot air from a hot air dryer of the corrugator

[0062] - Blade quality of a cutting blade of the corrugator, e.g. measured as the number of cuts made with this cutting blade

[0063] - Web speed in the corrugator

[0064] The determination and storage of the glue gap width is particularly advantageous, as, in a suitable configuration, the moisture content of a sheet can be derived from it. Two advantageous application scenarios are described below in which further processing by the second station downstream of the corrugator benefits from the previously determined production parameter stored in the data set. These two configurations can also be combined.

[0065] In a first advantageous application situation, the second station has a feed nip for a respective sheet and the feed nip has a nip width which is set depending on the production parameter. The second station is, for example, a printing, bending or punching machine. The sheets are typically taken individually from the stack and fed through the feed nip. If the nip width is smaller than the actual thickness of the sheet, there is a risk that the sheet will be compressed or shrunk and thus damaged. It is therefore advantageous to set the nip width as precisely as possible to the actual thickness of the sheet. This is implemented here and is possible above all because the data set contains corresponding information for controlling the second station, i.e. for setting the nip width.In particular, the manufacturing parameter, which was previously determined and then stored in the data set, is either directly the actual thickness of the sheet or at least a manufacturing parameter from which this thickness can be derived, e.g. a number of layers of the sheet and / or a grammage of the paper from which the sheet is made.

[0066] In a second advantageous application situation, the second station is a warehouse in which the stack is stored until further processing (e.g. in a third station downstream of the warehouse), and the second station only releases the stack for further processing when the production parameter has reached a certain limit due to storage. Further processing takes place, for example, in a third station downstream of the warehouse. This third station is, for example, a printing or gluing machine. The production parameter is in particular a temperature or a moisture content of the sheets in the stack. Both typically decrease over time, including during storage in the warehouse. By knowing the production parameter, it is possible to estimate its temporal development, e.g. using an experience-based model.Alternatively or additionally, the current value of the manufacturing parameter is measured in the warehouse, particularly on a recurring basis, and the data set is updated accordingly. However, it is generally sufficient to measure the stack's residence time in the warehouse and then, in combination with the value of the manufacturing parameter measured during production, release the stack after a predefined residence time.

[0067] A production line according to the invention is designed to carry out the method as described above.

[0068] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, the following schematically show:

[0069] Fig. 1 a corrugated board plant,

[0070] Fig. 2 a production line,

[0071] Fig. 3 a variant of the production line from Fig 2,

[0072] Fig. 4 shows a method for operating the production line of Fig. 2 or 3,

[0073] Fig. 5 a section of the production line from Fig. 3,

[0074] Fig. 6 another variant of the production line from Fig. 2,

[0075] Fig. 7 a stack and its contour,

[0076] Fig. 8 a variant of the stack and its contour,

[0077] Fig. 9 a first application example,

[0078] Fig. 10 shows a second application example. Fig. 1 shows a side view of an embodiment of a corrugated board plant 2. Figs. 2 and 3 each show an embodiment of a production line 4 having a plurality of stations 6. Specifically, the production line 4 has, as a first station, the aforementioned corrugated board plant 2, with which a plurality of sheets 8 are produced. During the production of the sheets 8, the corrugated board plant 2 first produces a corrugated board web 12 from a plurality of paper webs 10, which are then made into individual sheets 8. These sheets 8 are deposited in a stack 14 at the end of the corrugated board plant 2 and from there fed to a subsequent station 6. A stack 16 is formed from one or more of the sheets 8 in the stack 14. Each stack 16 thus contains at least one sheet 8, but typically—as shown in Fig. 1—several identical sheets 8.Overall, sheets 8 are produced successively, repeatedly and continuously with the corrugated board plant 2 and stacks 16 are formed therefrom, which are then output from the corrugated board plant 2 for further processing by one or more subsequent stations 6.

[0079] 1 to 3 also show an exemplary embodiment of a method for operating the production line 4 for producing and processing sheets 8 of corrugated cardboard. An exemplary embodiment of the method is shown as a flow chart in Fig. 4. During operation of the production line 4, sheets 8 are first produced in step S1 and then further processed in a step S2 in one or more stations 6 downstream of the corrugator 2. The term "processing" is understood broadly here in the sense of "handling" or "processing" or "handling". In the exemplary embodiment shown here, however, the production line 4 has at least one station 6 for forming, reworking, or modifying the sheets 8, apart from the corrugator 2.

[0080] In a third step S3, a production parameter 18 is determined, in particular measured, for the sheets 8 of the stack 16 and, in a step S4, stored in a data set 20 which is assigned to the stack 16. The data set 20 is assigned to the stack 16, for example, while the stack 16 is being formed or thereafter, and then before or while the stack 16 leaves the corrugator 2 or is transferred to the next station 6. The production parameter 18 is representative of the production of the sheets 8 and, in the exemplary embodiment shown, is determined while the sheets 8 of the stack 16 are being produced, which is illustrated in Fig. 4 by the fact that steps S1 and S3 are shown side by side. As a result, the data set 20 then contains a production parameter 18 at the time of production of the sheets 8.However, an alternative embodiment (not shown) is also suitable, in which the production parameter 18 is determined at least in close temporal proximity (e.g. + / - 5 min) to the production of the sheets 8, e.g. only when a stack 16 is formed from the sheets 8. In this case, it is assumed that the production parameter 18 changes only slightly over time and can therefore still be used with a brain-sufficient approximation (e.g. + / - 10%) to correctly specify or derive a property of the sheets 8. A configuration is also suitable in which, for correct assignment, the running time of the sheet 8 from the point at which the production parameter 18 is determined to the storage location 14 is simply measured. In the embodiment shown, several production parameters 18 are determined and stored in the data set 20. Fig. 1 shows several data sets 20, each for a stack 16. Optionally, each data set 20 additionally contains other parameters, e.g.Order or customer data.

[0081] As the product passes through production line 4 downstream of corrugator 2, data set 20 is optionally enhanced with additional data, such as time stamps and the type of subsequent processing. Alternatively or additionally, the previously determined production parameters 18 are re-determined and updated.

[0082] The production parameter 18 is an operating parameter of the corrugated board plant 2 (e.g. machine, process or control parameters) or a sheet parameter (e.g. product or material parameters of a sheet 8 or of a paper web 10 used to produce it). The production parameter 18 thus describes the production of the sheet 8 and thus indirectly a property of the sheet 8 or directly a property of the sheet 8 itself. The production parameter 18 typically varies during the production of the sheets 8. In order to be able to take this variation into account during further processing, the production parameter 18 is determined, in this case even repeatedly, and stored in the data record 20 for later control of a downstream station 6. For each stack 16, the value of the production parameter 18 at the time the sheets of the stack are produced is accordingly determined and stored.In the following, it is assumed, without loss of generality, that a stack 16 has several sheets 8 and that a single data record 20 is assigned to the stack 16, so that all sheets 8 of the stack 16 are assigned the same data record 20.

[0083] The production line 4 has at least one second station 6 (i.e., not the corrugator 2), to which the stack 16 is transferred for processing. The second station 6 is located downstream of the corrugator 2. The second station 6 processes the sheets 8 of the stack 16 individually, one after the other; however, simultaneous processing of several sheets 8 or the entire stack 12 is also possible.

[0084] Within the scope of the method, the data set 20 is stored in a control unit 22, which controls the processing of the sheets 8 of the stack 12 by the second station 6 depending on the production parameter 18. This adapts the further processing downstream of the corrugator 2 to the actual properties of the sheets 8 due to potentially varying production. Figs. 2 and 3 show two exemplary embodiments of such control by the control unit 22.

[0085] In order to ensure that the correct data set 20 is transferred to the respective station 6, which processes the assigned stack 16, the production line 4 shown here has a tracking system 24 for the stack 16. In this case, the production of a respective stack 16 is reported by the corrugator 2 to the tracking system 24, e.g. when this stack 16 is transferred to a conveyor belt, AGV or similar for further distribution in the production line 4. The tracking system 24 tracks the stack 16 as it passes through the production line 4, so that when a specific station 6 is reached, the data set 20 assigned to the stack 16 is actually used to control it. As a result, when a stack 16 is transferred to a respective station 6, the correct data set 20 is always used to control it.The tracking system 24 also knows, for example, how the stack 16 is transported further and in which order it is transferred to which stations 6. The tracking system 24 therefore assigns each stack 16, and thus also each data record 20, a virtual position within the production line 4, so that the assignment between data record 20 and stack 16 is correctly maintained. The stack 16 is physically transported through the production line 4, while the associated data record 20 virtually moves along with this stack 16. As soon as the stack 16 is transferred to a specific station 6, the data record 20 is also transferred to this station, or this station 6 is at least controlled depending on the data record 20. The other details of the tracking system 24, however, are initially of secondary importance.

[0086] In summary, in the method, the production of the sheets 8 is first documented in the data records 20 for the stacks 16, and this information (i.e., the data records 20) is then used to adapt the processing of the sheets 8 in the stations 6 downstream of the corrugator 2 to the actual properties of the sheets 8. The production line 4 knows which stack 16 or even which sheet 8 is located where and when within the production line 4. For this purpose, each individual stack 16 is seamlessly tracked from its production in the corrugator 2.

[0087] In principle, a physical element such as an ID tag, marking, QR code, barcode, RFID tag, etc. on the stack 16, the sheet 8 or on a means of transport can serve as a type of digital routing slip. The physical element then contains the data record 20 or refers to it within a central database. The physical element then physically moves with the stack 16, ensuring that the data record 20 is correctly assigned to the stack 16. The physical element is then read at a respective station 6 using a suitable reading device. In the present case, however, an embodiment is shown in which such a physical element is neither required nor used. Rather, the data record 20 itself is not a physical element, but merely a virtual element, i.e. data that is stored in the control unit 22 and can be transmitted along a suitable signal path (e.g., signal line or wirelessly).In this case, data record 20 is stored separately from stack 16, i.e., data record 20 is not physically connected to stack 16. Alternatively or additionally, data record 20 is transferred separately from stack 16, i.e., data record 20 is not transferred via the same path as stack 16. The preferred method described here as an example does not require a separate physical element on stack 16 or sheet 8 for the purpose of referencing the respective data record 20. Data record 20 is merely virtually "attached" to the stack and thus assigned to it. No persistent marking is applied to stack 16 itself.

[0088] The control unit 22 is essentially a part of the production line 4 and, depending on the configuration, controls one or more stations 6 of the production line 4. In one possible configuration, the control unit 22 is part of a higher-level control device (not shown) of the production line 4 for carrying out the method, or is even identical thereto. There are basically two variants for the control unit 22: this is either a central control unit 22, as shown by way of example in Fig. 2, or a decentralized control unit 22, as shown by way of example in Fig. 3.

[0089] In the first variant (Fig. 2), the control unit 22 is a central control unit 22 of the production line 4, in which the data set 20 is stored (centralized approach). The data sets 20 for the various stacks 16 are thus stored centrally in the control unit 22 and then used by it to control the individual stations 6. To control an individual station 6, either the respective data set 20 for the stack 16 to be processed is transferred from the control unit 22 to the second station 6, e.g., to a sub-control unit 26 of the second station 6, and the second station 6 derives a suitable control command from the data set 20. Alternatively, the data set 20 remains in the central control unit 22, and this derives a suitable control command from the data set 20, with which the control unit 22 then controls the second station 6, e.g., also via a sub-control unit 26.In the first case, the control command is derived centrally (central intelligence), whereas in the second case, it is derived decentrally (decentralized intelligence). A combination is also possible (hybrid intelligence), in which at least one station 6 receives the data set 20 and derives the control command itself, and at least one other station 6 receives the control command directly from the central control unit 22.

[0090] In the second variant (Fig. 3), the data set 20 is stored decentrally (decentralized approach). The control unit 22 is then not a central control unit, but a decentralized control unit 22, which is part of the second station 6 and primarily or exclusively controls this second station 6. In Fig. 3, each additional station 6 then has its own control unit 22, so that the data set 20 is then transferred to each of the stations 6 in order to process the assigned stack 16 accordingly as soon as it is transferred to the respective station 6. In principle, it is also possible to transfer the data set 20 to several stations 6 simultaneously after it has been created. In Fig. 3, however, the data set 20 is transferred from one station 6 to the next station 6 parallel to the stack 16 and is thus passed on together with the stack 16.The data record 20 is then only ever stored in the control unit 22 of the station 6 that will next process the assigned stack 16. The data record 20 is therefore also passed on from station 6 to station 6, analogous to the physical transfer of the stack 16 from station 6 to station 6. This ensures that the assignment between stack 16 and data record 20 is maintained as it passes through the production line 4. In principle, it is possible to implement this with a data carrier or an ID tag that is physically linked to the stack 16, e.g., attached to it or printed on it. In the present case, however, a purely virtual link between the data record 20 and the stack 16 is shown. In other words: the data record 20 is only virtually assigned to the stack 16. This is done, for example,by means of the tracking system 24, which continuously tracks the stack 16 so that it is known at any time where the stack 16 is located in the production line 4.

[0091] The central and decentralized storage of the data set 20 can in principle be combined, e.g. in such a way that the data set 20 is stored both in a central control unit 22 of the production line 4 and at the same time decentrally in one or more stations 6, e.g. independently of the central control unit 22 or based thereon.

[0092] The stack 16 is transported within the production line 4 along a transport path 28 from station 6 to station 6, e.g. from station 6a to station 6b as shown by way of example in Fig. 3. Each time the stack 16 is transferred from one station 6a to the next station 6b (and generally when transferred from any station 6 to another station 6), the data record 20 is also transferred along a data path 30 from one station 6 to the next station 6 in Fig. 3. The transport path 28 is the path along which the stack 16 is physically transported through the production line 4. The data path 30 is parallel (in a functional sense, not necessarily physically) to the transport path 28, but independent of it in that the data record 20 is not physically attached to the stack 16, but merely virtually. The data path 30 is the path along which the data set 20 is transmitted to the respective stack 16.The data path 30 follows the transport path 28 at least virtually, ensuring that the assignment between stack 16 and data record 20 is maintained. However, this is not mandatory as long as the tracking system 24 at least tracks stack 16 so that at least its position along the transport path 28 is known. However, when the data record 20 is transferred from station 6 to station 6 in a similar way to the transfer of stack 16, a tracking system 24 is unnecessary; the tracking of stack 16 is predetermined by the transport path 28. Since the data record 20 is transferred in parallel, the assignment to the correct stack 16 is inherently maintained. A central definition and knowledge of the transport path 28 are not required. The data path 30 has, for example, a physical signal line from one station 6 to the next station 6, but a corresponding wireless connection is equally suitable.For example, corresponding interfaces or logical inputs and / or outputs of two stations 6 of the production line 4 are connected to each other via a signal line.

[0093] Fig. 5 shows an embodiment for the transfer of a stack 16 and an associated data set 20. For this purpose, a section of the production line 4 is shown, in which two stations 6 can be seen, e.g. the corrugator 2 and a subsequent, second station 6 or generally two stations 6. The preceding station 6 has an output conveyor belt 32 and the subsequent station 6 has an acceptance conveyor belt 34, both conveyor belts 32, 34 are part of the transport path 28. During the transfer of the stack from the output conveyor belt 32 to the acceptance conveyor belt 34, a presence sensor 36 of the subsequent station 6 detects the transfer of the stack 16 to this subsequent station 6, which then, in response, receives or requests the data set 20 from the preceding station 6 via the signal line (i.e. the data path 30) (pull principle).An equivalent embodiment (not explicitly shown) is one in which a presence sensor 36 at the preceding station 6 detects that the stack 16 is leaving this preceding station 6 and then initiates the transmission of the data set 20 to the subsequent station 6 (push principle). The presence sensor 36 is, for example, a light barrier. Instead of the data set 20, control data or a reference to such data or to the data set 20 in a database can also be transmitted.

[0094] In one possible embodiment, the assignment between the data set 20 and the stack 16 is maintained as it passes through the production line 4 by detecting and tracking the stack 16 with a camera system 38. This is shown as an example in Fig. 6. The camera system 38 is part of the tracking system 24. The camera system 38 has one or more cameras 40, each of which monitors one or more stations 6 of the production line 4 and detects and tracks the respective stacks 16. To detect the stacks 16 based on one or more images from a respective camera 40, the camera system 24 has an image recognition unit 42. Each stack 16 is detected for the first time during its production at the end of the corrugator 2 using the tracking system 24, and the corresponding data set 20 is also assigned thereto.The stack 16 now passes through the production line 4 along a corresponding transport path 28 and is continuously tracked by the camera system 38 and in any case tracked in such a way that the correct data set 20 is also transferred when it is transferred to one of the stations 6 of the production line 4.

[0095] In an exemplary embodiment, a contour 44 of the stack 16 is determined and the data set 20 is assigned to this contour 44. This determination of the contour 44 is also referred to as “stack shape recognition”. For this purpose, for example, the camera system 38 already described is used. Examples of contours 44 are shown in Figs. 7 and 8. Fig. 7 shows a stack 12 in a plan view on the right and its contour 44 on the left. Fig. 8 shows a stack 12 in a side view on the right and its contour 44 on the left. When the stack 16 is transferred to the second station 6, the contour 44 of the stack 16 is (again) determined and then the data set 20 which is assigned to this contour 44 is used to control the second station 6. In other words: at station 6, the contour 44 of the stack 16 and thus also the stack itself is recognized and then the correct data set 20 is used to control this station 6.In this way, the use of a separate physical element for detecting (i.e., identifying) the stack 16 is dispensed with; instead, the contour 44 of the stack 16 itself is used for this purpose. Aside from the views of a stack 16 shown in Figs. 7 and 8, other views are also suitable for determining the contour 44, especially perspective views and / or partial views.

[0096] 7 and 8, the term “contour” 44 of a respective stack 16 is understood to mean a circumferential line of the stack 16 or a part, e.g. just one side, of this circumferential line. The circumferential line is obtained, for example, within the image recognition unit 42 by means of an edge detection method from an image generated by the camera system 38. A sensor at the entrance to a respective station 6, e.g. the presence sensor 36 already described, is also particularly suitable, so that the contour 44 is automatically determined when the stack 16 is transferred to the corresponding station 6. Since the contour 44 can fundamentally change due to the processing in a respective station 6, the contour 44 is determined again (i.e. updated) at the end of a respective station 6 if necessary.

[0097] As already described, at least one production parameter 18 is determined for the sheets 8 of the stack 16. In the present case, this already occurs during the production of the sheets 8, alternatively while the stack 16 is being formed from them. In any case, the production parameter 18 is determined in the context of the production of the sheets 8 and the stack 16. In the exemplary embodiment in Fig. 1, the production parameter 18 is determined by measuring it within the corrugated board system 2, here with a sensor unit 46 which is integrated into the corrugated board system 2. Several such sensor units 46 are shown in Fig. 2, so that accordingly several production parameters 18 are also determined. In the present case, the sensor units 46 are already present in order to measure the production parameter 18 for controlling or monitoring the corrugated board system 2.

[0098] The production parameter 18 is, for example, one of the following sheet parameters: thickness of a sheet 8, moisture of a sheet 8, or warp of a sheet 8. These production parameters 18 are relevant for a variety of potential further processing in stations 6 downstream of the corrugator 2.

[0099] The sheet parameters are material or product parameters that directly characterize the sheets 8 or the materials used to produce them. Alternatively or additionally, several operating parameters of the corrugated board plant 2, also referred to as machine parameters, are determined and used. Accordingly, at least one of the production parameters 18 is then an operating parameter of a production line section of the corrugated board plant 2. An operating parameter characterizes the state of the corrugated board plant 2 during the production of the sheets 8, i.e., the production conditions. Thus, an operating parameter does not characterize the product produced by the corrugated board plant 2 (the sheets 8) directly, but only indirectly, and is therefore determined and used at least to derive one or more properties of the sheets 8.The production line part is, for example, a unwinder 48, a splicer (here integrated into the unwinder 48), a gluing unit 52, a preheater 54, a single facer 56, a double facer 58, a printer 60, an applicator (not explicitly shown), a cross cutter (not explicitly shown), a cutting and creasing machine 62 and the like, or an individual component of the corrugator 2, e.g. corrugating roller, heating roller, heating plate, spray bar, cutting knife and the like.

[0100] Suitable operating parameters are, for example, the following operating parameters: glue gap width in the gluing unit 52; glue quantity applied in the gluing unit 52; properties of the glue; moisture quantity applied with a spray bar, steam bar or similar; temperature of a drying or heating element, e.g. heating roller of the preheater 54, heating plate in the double facer 58, IR dryer, hot air dryer; and others.

[0101] With reference to Figs. 9 and 10, two possible application situations are described below in which further processing by the second station 6 downstream of the corrugator 2 benefits from the previously determined production parameter 18 stored in the data set 20. Individual or all aspects of these two embodiments can, in principle, also be combined with one another.

[0102] In a first advantageous application situation (Fig. 9), the second station 6 has a feed gap 64 for a respective sheet 8, and the feed gap 64 has a gap width 66, which is adjusted depending on the production parameter 18. The second station 6 is, for example, a printing, bending, or punching machine. The sheets 8 are removed individually from the stack 16 and fed through the feed gap 64. The data set 20 provides information for controlling the second station 6, i.e., for adjusting the gap width 66. The production parameter 18, which was previously determined and then stored in the data set 20, is either directly the actual thickness of the sheet 8 or at least a production parameter 18 from which this thickness can be derived. In a second advantageous application situation (Fig. 10), the second station 6 is a warehouse in which the stack 16 is stored until further processing (e.g.in a third station 6 downstream of the warehouse), and the second station 6 only releases the stack 16 for further processing when the production parameter 18 has reached a certain limit due to storage. In Fig. 10, the warehouse is shown with a dashed line. Several stacks 16 are stored in the warehouse. Further processing takes place, for example, in a third station 6 downstream of the warehouse. This third station 6 is, for example, a printing or gluing machine. The production parameter 18 is, for example, a temperature or a moisture content of the sheets 8 of the stack 16. Both typically decrease over time, including during storage in the warehouse. By knowing the production parameter 18, it is possible to estimate its temporal development. Alternatively or additionally, the current value of the production parameter 18 is measured in the warehouse, and the data set 20 is updated accordingly.In principle, however, it is also sufficient to measure the residence time of the stack 16 in the warehouse and then, in combination with the value of the production parameter 18, which was measured during production, to release the stack 16 after a predefined residence time.

[0103] List of reference symbols

[0104] 2 corrugated board lines

[0105] 4 Production line

[0106] 6, 6a, 6b Station

[0107] 8 sheets

[0108] 10 paper web

[0109] 12 corrugated cardboard sheets

[0110] 14 filing

[0111] 16 stacks

[0112] 18 manufacturing parameters

[0113] 20 data sets

[0114] 22 Control unit

[0115] 24 tracking system

[0116] 26 Sub-control unit

[0117] 28 Transport path

[0118] 30 Data path

[0119] 32 Output conveyor belt

[0120] 34 Acceptance conveyor belt

[0121] 36 Presence sensor

[0122] 38 camera system

[0123] 40 Camera

[0124] 42 Image recognition unit

[0125] 44 Contour

[0126] 46 Sensor unit

[0127] 48 dispensers

[0128] 52 Glue plant

[0129] 54 preheaters

[0130] 56 Single Facer

[0131] 58 Double Facer

[0132] 60 printers

[0133] 62 Cutting and creasing machine

[0134] 64 Feed gap Gap width Step “Production” Step “Processing” Step “Determination of a production parameter” Step “Storage in a data set and assignment to a stack”

Claims

Claims 1. Method for operating a production line (4) for producing and processing sheets (8) of corrugated cardboard, a. wherein the production line (4) has, as a first station (6), a corrugator (2) with which a plurality of sheets (8) are produced, b. wherein a stack (16) is formed from one or more of the sheets (8), c. wherein at least one production parameter (18) is determined for the sheets (8) of the stack (16) and stored in a data set (20) which is assigned to the stack (16), d. wherein the production line (4) has at least one second station (6) to which the stack (16) is transferred for processing, e. wherein the data set (20) is stored in a control unit (22) which controls processing of the sheets (8) of the stack (16) by the second station (6) depending on the production parameter (18).

2. Method according to claim 1, wherein the production line (4) has a tracking system (24) with which the stack (16) is tracked as it passes through the production line (4), so that when a specific station (6) is reached, this station is also controlled depending on the associated data set (20).

3. Method according to claim 1 or 2, wherein the control unit (22) is a central control unit (22) of the production line (4).

4. Method according to one of claims 1 to 3, wherein the data record (20) is stored decentrally and is transferred from one station (6) to the next station (6) in parallel with the stack (16).

5. Method according to one of claims 1 to 4, wherein within the production line (4) the stack (16) is transported along a transport path (28) from station (6) to station (6), wherein during the transfer of the stack (16) from one station (6) to the next station (6) the data set (20) is also transferred along a data path (30) from one station (6) to the next station (6).

6. Method according to one of claims 1 to 5, wherein the association between the data record (20) and the stack (16) is maintained as it passes through the production line (4) by detecting and tracking the stack (6) with a camera system (38).

7. Method according to one of claims 1 to 6, wherein a contour (44) of the stack (16) is determined and the data set (20) is assigned to this contour (44), wherein when the stack (16) is transferred to the second station (6), the contour (44) of the stack (16) is determined and then the data record (20) assigned to this contour (44) is used to control the second station (6).

8. The method according to any one of claims 1 to 7, wherein the data record (20) is stored and transferred separately from the stack (16).

9. Method according to one of claims 1 to 8, wherein the production parameter (18) is determined by measuring it within the corrugated cardboard plant (2) with a sensor unit (46) which is integrated into the corrugated cardboard plant (2).

10. The method according to any one of claims 1 to 9, wherein the manufacturing parameter (18) is one of the following manufacturing parameters (18): a. thickness of a sheet (8), b. Moisture of a sheet (8), c. Warp of a sheet (8).

11. Method according to one of claims 1 to 10, wherein the production parameter (18) is an operating parameter of a production line part (48, 52, 54, 56, 58, 60, 62) of the corrugated board plant (2).

12. Method according to one of claims 1 to 11, wherein the second station (6) has a feed gap (64) for a respective sheet (8), wherein the feed gap (64) has a gap width (66) which is set depending on the production parameter (18).

13. The method according to any one of claims 1 to 11, wherein the second station (6) is a warehouse in which the stack (16) is stored until further processing, wherein the second station (6) only releases the stack (16) for further processing when the production parameter (18) has reached a certain limit value due to the storage.

14. Production line (4) which is designed to carry out a method according to one of claims 1 to 13.

Images