Method and device for detecting a number of corrugated board sheets

Abstract

The invention relates to a method for detecting a number of corrugated board sheets in a stack, comprising: - detecting a surface modulation in an overlapping shingled stream by means of sensors, - determining the number of corrugated board sheets on the basis of the detected surface modulation, and - outputting the number of corrugated board sheets. The proposed solution also comprises a device for detecting a number of corrugated board sheets in a stack, a computer program product, and a corrugating machine.

Description

[0001] BHS Corrugated Maschinen- und Anlagenbau GmbH Paul-Engel-Straße 1

[0002] 92729 WEIHERHAMMER

[0003] Method and apparatus for capturing a number of corrugated cardboard sheets

[0004] Description

[0005] The proposed solution relates to a method for detecting a number of corrugated cardboard sheets in a stack and a device set up for this purpose.

[0006] Methods and devices for counting the number of corrugated board sheets are known in the corrugated board manufacturing industry. The aim of such methods and devices is to determine, at least approximately, how many corrugated board sheets are in a stack. For example, the number can be determined based on the cutting signals sent by a cross-cutter of a corrugated board machine. However, this approach can lead to unsatisfactory results. If, for example, sample sheets are removed by the operating personnel and non-destructive quality control checks are carried out, the number determined by the cross-cutter's cut count may differ from the actual number in the stack. Similarly, errors during the cutting process can cause the actual number to differ from the number determined by the cross-cutter.

[0007] Therefore, there is a need to improve methods and devices for capturing a number of corrugated cardboard sheets.

[0008] This problem is solved by the method according to claim 1 and a device according to claim 10. The proposed method for detecting the number of corrugated board sheets in a stack therefore comprises at least the following steps: sensorial detection of a surface modulation of a shingle stream, determination of the number of corrugated board sheets based on the detected surface modulation, and output of the number.

[0009] Sensory detection of surface modulation and determination of the number of corrugated board sheets based on this detection can enable the determination, and in particular the automatic determination, of the number of sheets independent of production parameters. Therefore, the proposed method can determine and correctly output the actual number of corrugated board sheets even if the number of finished corrugated board sheets transported to a stacking tray per unit of time (sheet flow) is unexpectedly changed or altered by external interventions.

[0010] The term "finished" in this context can mean that an endless web of corrugated board has been repeatedly cut in a cross-cutting unit, perpendicular to the conveying direction, to obtain individual sheets or panels. These sheets are then transported via a conveying system, such as a conveyor belt, to a stacking tray, where they are arranged in a stack. During transport, the sheets lie adjacent to each other along the conveying direction, but are not necessarily arranged in a regular pattern. Typically, adjacent sheets overlap on the conveying system, resulting in a so-called shingle pattern. The sheets arranged on the conveying system thus have a top and bottom surface along the vertical direction. Due to the aforementioned arrangement of the sheets, both surfaces generally exhibit a continuous but uneven profile (surface modulation).Here, uneven surface contours mean that each of the two surfaces has flat sections angled relative to each other, particularly obtusely angled ones. If individual corrugated sheets are removed from the sheet flow before stacking, or if the number and / or density of the corrugated sheets on the conveyor deviates from a predicted number and / or density, this is reflected in a spatial change in the surface modulation. During operation of the conveyor, this also leads to a temporal change in the surface modulation. These changes can be automatically taken into account with the proposed method. In particular, it can automatically account for deviations in the sheet flow from a flow assumed based on production parameters, such as the removal of sample sheets or production errors like separation errors.This allows us to determine how many corrugated sheets reach a stacking tray at any given time, and therefore how many sheets have already been stacked. The number of stacked sheets can be assigned to the stack after stacking is complete, so that the customer can be informed of the correct number of sheets in a stack. Furthermore, by evaluating the actual number of sheets (i.e., the number determined using the proposed method) and the number of cuts made by the cross-cutter, faulty cuts can be identified. This allows for the automated determination of the cross-cutter's cutting reliability. Consequently, maintenance requirements for the cross-cutter can be automatically identified.

[0011] The dispensing of a specific number of corrugated cardboard sheets can be indicated by an analog and / or digital signal. For example, the dispensing can be done with a visual and / or audible signal, informing operators of the number of sheets in a stack. This can enable them to stop a stacking operation or to assign a specific number of stacked sheets to a particular pile.

[0012] Alternatively or additionally, the output of the count can include sending a control signal to a monitoring device or control unit, e.g., the stacking unit. This allows a stacking process to be controlled. The control can, in particular, include ending the stacking process and assigning the number of stacked corrugated sheets to the stack. Specifically, the output can include automatically generating a stack telegram containing the number of corrugated sheets determined based on surface modulation. After the stack has been transported out, the stack telegram can be transmitted to a predetermined recipient, in particular a production monitoring system or a customer-side system.

[0013] In one embodiment of the proposed method, the surface modulation of the corrugated sheet flow can involve a height variation orthogonal to the conveying direction of the corrugated sheet flow. The surface modulation can thus be detected in a stationary measuring area through which the corrugated board sheets are transported by the conveying device during operation of the corrugating plant. This allows the surface modulation to be recorded as a time-dependent measurement. This can simplify the measurement process. In principle, the surface modulation can affect the upper surface (top side) and / or the lower surface (bottom side) of the corrugated sheet flow. A detection device for the sensory acquisition of the surface modulation can therefore be arranged both above and below the corrugated sheet flow. This can increase design flexibility for the arrangement of such a sensory device.Capturing both the top and bottom surfaces can compensate for errors and thus increase the accuracy of the determination.

[0014] According to a further embodiment of the proposed method, surface modulation can be performed using time-resolved distance measurements from a reference point to a measurement area on the surface of the scale stream. Accordingly, the distance between the reference point and the measurement area can be measured repeatedly or continuously. As the scale stream is transported through this measurement area, the surface modulation can be recorded in the form of time-resolved measurements.

[0015] Area-based, linear, and point-based measuring ranges are all conceivable. An area-based measuring range allows for the detection of surface modulation along the conveying direction even when the conveying system is not in operation and the corrugated sheets are not being transported through the measuring range. Conversely, both area-based and linear measuring ranges allow for the detection of an area section of the surface of the flake stream while the conveying system is in operation. Measurements acquired with an area-based measuring range can exhibit higher redundancy compared to those acquired with a linear measuring range, which can improve error tolerance. Measurements acquired with a point-based measuring range can simplify counting and therefore save computing resources, particularly in computer-implemented systems.

[0016] According to a further embodiment of the proposed method, the number of corrugated sheets can be determined by identifying joints in the surface modulation of the shingled corrugated sheets. A joint can be defined as an area where two adjacent corrugated sheets overlap. The course of a lower and upper surface of the shingled sheet stream along the conveying direction can exhibit a discontinuity, a local extremum, or a global extremum at each joint. Extrema can occur when the adjacent, overlapping, and essentially flat corrugated sheets form an obtuse angle. Each joint can be characterized by a maximum and an adjacent minimum. Thus, both maxima and minima can be used to identify joints.A discontinuity may occur if the adjacent, overlapping, and essentially flat corrugated cardboard sheets enclose an angle of 180°.

[0017] In the case of a discrete measurement of a distance s for different spatial and / or temporal support points, extrema can be determined via a first-order difference quotient As / Ai and / or a second-order difference quotient A. 2 s / Ai 2 be determinable:

[0018] In this case, a shock at a support point / can be detected if the first-order difference quotient for / is equal to zero or changes its sign from i-1 to / and, in addition, the second-order difference quotient at the point / is not equal to zero.

[0019] The same applies to the first and second order differential quotients within the framework of a continuous measurement.

[0020] In the case of time-resolved distance measurement, any data point can be a measurement location. In the case of spatially resolved distance measurement, any data point can be a point along a spatial direction. With spatially and temporally resolved measurements, i.e., with non-point-shaped measurement areas and a flux transported relative to the measurement area, the measured values ​​can depend on both spatial and temporal data points.

[0021] For example, a linear measuring range, composed of a multitude of measuring points, can extend orthogonally to a conveying direction of the conveyor system. If distance measurements are performed over the entire measuring range X during operation of the conveyor system over an operating time T, a two-dimensional array of distances s is obtained as a function of time t and position x: s(x, t) with x ∈ X, t ∈ ET. By determining the points of discontinuity, difference quotients, or differential quotients along both axes (t and x), the pattern of impacts within the measuring range X and within the operating time T can be determined. This makes it possible to identify corrugated sheets arranged adjacent to each other along the conveying direction, corrugated sheets adjacent to each other perpendicular to the conveying direction, as well as twisted and incompletely separated corrugated sheets.

[0022] For example, distance measurements s(t, x) can be used to identify discontinuities along the f-axis, difference quotients along the t-axis, or differential quotients along the f-axis, indicating when an impact crosses the measurement range X. In principle, the discontinuities, difference quotients, or differential quotients can be calculated independently for each of the many measurement points x within the measurement range X, thus allowing for redundant determination of the occurrence of an impact. If an impact is identified at some of the points x within the measurement range X, but not within a predetermined time interval in the rest of the measurement range X, an incomplete separation of the corrugated cardboard sheets can be detected.

[0023] For example, distance measurements s(t, x) across discontinuities along the x-axis, difference quotients along the x-axis, or differential quotients along the x-axis can be used to identify the point x at which a collision crosses the measuring range X. If a collision is identified at several times t only in a spatially limited area within the measuring range X, corrugated cardboard sheets adjacent to the conveying direction can be detected.

[0024] Each identified impact can represent a transition from one corrugated sheet to an adjacent one. Therefore, the number of impacts identified in a shingle stream can correspond to the number of corrugated sheets in that stream. According to a further embodiment of the proposed method, the sheet stream can thus be determined based on the number of impacts of the shingled corrugated sheets passing a predetermined location, in particular the measuring area, per unit of time.

[0025] Taking into account the distance between the point where the arc flow is detected and the stacking device, a time (retardation) can be determined, based on the conveyor belt speed, that a point on the conveyor belt needs to travel from the point where the arc flow is detected to the stacking device. The arc flow thus defines the number of corrugated board sheets arriving at the lifting table with this retardation.

[0026] From the number of corrugated board sheets reaching the stack per unit of time, the total number of sheets in the stack can be determined by counting them over a period of time. According to a further embodiment of the proposed method, the number of corrugated board sheets in a stack can therefore be determined by integrating the sheet flow over time.

[0027] The proposed method can be used for distance measurement with any detection device or sensor designed for distance measurement. This makes it possible, in particular, to utilize cost-effective sensors or sensors already present in an existing corrugated board plant. This can reduce implementation effort. For example, a suitable detection device could be configured with a laser.

[0028] According to a further embodiment of the proposed method, the surface modulation of a shingle stream can be detected at a multitude of measuring areas. The proposed method can thus provide for the detection of the surface modulation of a shingle stream in various measuring areas and / or the detection of the surface modulation of different shingle streams in at least one measuring area each. This can, in particular, enable the detection of surface modulations of divided shingle streams fed to different stacking devices directly in front of or above a lifting table. This can also enable the detection of the number of corrugated sheets in different stacks of multi-layer dry ends, e.g., with duplex or triplex construction.

[0029] As an example, the proposed method can be implemented using several detection devices arranged at different measuring positions along the corrugated board line. Each detection device can be configured to detect the surface modulation of a shingle stream within a specific measuring area. This allows for the parallel detection of a number of corrugated board sheets in multiple stacks.

[0030] According to a further exemplary embodiment, the proposed method can also be carried out with at least one scanning device movable along the corrugated board machine to record the number of different measuring positions along the machine. Particularly with regard to the sequential transport of corrugated board sheets to different stacks, this can reduce the number of scanning devices required and thus lower costs.

[0031] According to one embodiment of the proposed method, at least one detection device for capturing surface modulation of a scale stream can be moved by external force into a selected measuring position from a plurality of possible positions. This makes it possible, in particular, to automatically and job-specifically adjust a detection device to a suitable measuring position. For example, the use of one of several stacking devices in the stacking tray may be required for a specific job. The selected measuring position can then be located, for instance, above or directly in front of the lifting table of the intended stacking device.

[0032] According to one embodiment of the proposed method, the measurement position can be selected via user input. For example, operating personnel can use an input device, such as a touchscreen, mobile phone, computer, or switch, to specify the selected measurement position.

[0033] Alternatively or additionally, the proposed procedure can include reading in order metadata and automatically selecting the measurement position based on the order metadata.

[0034] The order metadata can include, for example, when and what type of corrugated board is to be produced and in how many rolls. Thus, based on the order metadata, it can first be determined which stacking device from a plurality of stacking devices in the stacking tray will be used for the order. Each of the stacking trays can be assigned a measuring position. Therefore, the measuring position assigned to the selected stacking device can be chosen based on the order metadata.

[0035] According to a further embodiment of the proposed method, the procedure can also include recording the target number of corrugated board sheets in a stack. This makes it possible to compare the actual number of corrugated board sheets recorded with the target number. For example, the proposed method can determine when the target number has been reached. Upon reaching the target, the number of corrugated board sheets can be output. In particular, the output can include a control signal for the stacking unit, which instructs the stacking unit to transport the completed stack. Furthermore, the output can include the generation of a stack telegram, which contains, among other things, the number of sheets.

[0036] According to a further embodiment of the proposed method, the lowering speed of the lifting table can be controlled based on the arc current.

[0037] For example, the lowering speed can be chosen to be proportional to the number of corrugated cardboard sheets arriving at the lifting table via the retarder (linear relationship). This linear relationship serves only as an illustrative example. In principle, other relationships between the lowering speed and the sheet flow are conceivable and possible.

[0038] According to a further embodiment of the proposed method, the process can also include measuring the height of the already stacked corrugated board sheets (stack height). In particular, the stack height can be measured using the same detection device that also measures surface modulation. The stack height can, for example, be used as a control variable for regulating the lowering speed of lifting tables. Thus, a system designed for the proposed method can reduce the number of required detection devices. This can reduce costs and increase the reliability of the corrugated board production line.

[0039] According to a further embodiment of the proposed method, the lowering speed of the lifting table can be controlled based on the stack height.

[0040] A height difference (fall height) can exist between the end section of a conveyor facing the lifting table and the top edge of the stack. This fall height can be determined by the stack height as the difference between the distance of the end section of the conveyor to the lifting table and the stack height. According to a further embodiment of the proposed method, the lowering speed can be adjusted so that the fall height remains constant. In particular, the fall height can be maintained at a predetermined value (setpoint). This can improve stack quality.

[0041] Naturally, the proposed solution also includes an implementation of the proposed method as a computer-implemented procedure. In this case, a computer is configured to execute machine-readable instructions that cause the computer to carry out the proposed procedure.

[0042] The aforementioned problem is also solved by the proposed device for detecting a number of corrugated board sheets. This device comprises at least: at least one detection device for detecting a surface modulation of a shingle stream, an output device for dispensing a number of corrugated board sheets, and a control unit connected to the at least one detection device and the output device, which is configured to determine a number of corrugated board sheets in a stack based on the detected surface modulation and to dispense them via the output device.

[0043] Capturing the surface modulation with the at least one detection device and determining the number of corrugated board sheets based on the captured surface modulation can enable, in particular, automatic determination of the number of sheets independent of production parameters. Thus, the proposed device can determine the actual number of corrugated board sheets even if the number of sheets transported to a stacking tray per unit of time (sheet flow) changes unexpectedly. Specifically, it can automatically account for deviations in the sheet flow from a flow assumed based on production parameters, such as the removal of sample sheets or production errors like separation errors. This allows for the determination of how many corrugated board sheets reach a stacking tray at any given time and, consequently, how many sheets have already been stacked.The number of stacked corrugated board sheets can be assigned to the stack after stacking is complete, allowing customers to be informed of the correct number of sheets in a stack. Furthermore, by evaluating the actual number of sheets (i.e., the number determined using the proposed method) and the number of cuts made by the cross-cutter, faulty separations can be identified. In addition, the separation reliability of the stacking process can be automatically determined.

[0044] This allows for the automated detection of maintenance needs on the cross cutter.

[0045] The at least one detection device can be configured to send the detected surface modulation to the control unit. The control unit can be configured to receive the surface modulation and, in response to the receipt, determine the number of corrugated board sheets. Continuously, periodically, or upon the occurrence of a predetermined event, the control unit can send this information to the output device. The output device can be configured to output the received number, whereby the output of the specified number of corrugated board sheets can be accompanied by an analog and / or digital signal. For example, the output can be accompanied by a visual and / or audible signal, which can inform operators about the number of corrugated board sheets in a stack. This can enable the targeted termination of a stacking operation or the allocation of a number of stacked corrugated board sheets to a specific stack.

[0046] Alternatively or additionally, the output of the count can include sending a control signal to a monitoring device or control unit, e.g., the stacking unit. This allows a stacking process to be controlled. The control can, in particular, include ending the stacking process and assigning the number of stacked corrugated sheets to the stack. Specifically, the output can include automatically generating a stack telegram containing the number of corrugated sheets determined based on surface modulation. After the stack has been transported out, the stack telegram can be transmitted to a predetermined recipient, in particular a production monitoring system or a customer-side system.

[0047] Within the framework of the proposed solution, a connection is fundamentally understood as one in which the connected elements can send and receive signals. Therefore, both wireless and wired connections are conceivable.

[0048] The mention of at least one acquisition device, the control unit, and the output device as elements of the proposed device does not imply spatial separation. Rather, the elements can also be combined in a single device, for example, on a common circuit board. It is also conceivable and possible that the control unit is simultaneously configured for output and thus also serves as the output device.

[0049] According to a further embodiment of the proposed device, the at least one detection device can be arranged above or below a conveyor belt. Furthermore, the at least one detection device can be arranged opposite to the conveying direction, in front of or above the lifting table. In particular, by placing the at least one detection device in or shortly before the stacking device, the probability of a change in the arc flow after the surface modulation has been detected can be reduced.

[0050] According to a further embodiment of the proposed device, the at least one detection device can be configured with a sensor designed for distance measurement. In particular, the at least one detection device can be configured with a laser.

[0051] Of course, the proposed device can also have multiple detection devices. This can, for example, increase fault tolerance and reliability.

[0052] According to a further embodiment of the proposed device, at least one detection device for measuring surface modulation can be set up in different measuring areas of the corrugated board plant.

[0053] For example, the proposed device can have several detection units arranged at different measuring positions along the corrugated board line. Each detection unit can be configured to detect the surface modulation of a shingle stream within a specific measuring area. This can enable the parallel detection of a number of corrugated board sheets in multiple stacks.

[0054] According to a further exemplary embodiment, the proposed device can also be equipped with at least one detection unit movable along the corrugated board line for recording the number of different measuring positions along the line. Particularly with regard to the sequential transport of corrugated board sheets to different stacks, this can reduce the number of components required and thus lower costs. According to one embodiment of the proposed method, at least one detection unit for recording surface modulation of a shingle stream can be moved by external force to a selected measuring position from a plurality of possible positions. Accordingly, the proposed device can be equipped with an electronically controlled adjustment device by which the at least one detection unit can be adjusted between at least two different measuring positions along the length of the corrugated board.This allows, in particular, the automated and order-specific adjustment of a scanning device to a suitable measuring position. For example, the use of one of several stacking devices in the stacking tray may be required for a specific order. The selected measuring position can then be, for instance, above or directly in front of the lifting table of the stacking device.

[0055] For example, the control unit can be configured to receive the selected measurement position and send an adjustment command to the adjustment device, whereby the adjustment device, in response to receiving the selected measurement position, adjusts the at least one detection device to the selected measurement position. Alternatively, the adjustment device itself can be configured to receive the selected measurement position.

[0056] According to a further embodiment of the proposed device, the device can include an input device connected to the control unit, such as a touch display or a switch. The measurement position can be selected via user input using this input device.

[0057] Alternatively or additionally, the proposed device can be configured to read order metadata and automatically select the measurement position based on this data. For example, the device can include a receiver connected to the control unit for reading the order metadata. The receiver can be configured to receive data from a storage element, such as an RFID chip, or from a local or remote computer.

[0058] The order metadata can include, for example, when and what type of corrugated board is to be produced and in how many webs. Thus, based on the order metadata, it can first be determined which stacking device from a plurality of stacking devices in the stacking tray will be used for the order. Each stacking tray can be assigned a measuring position. Therefore, the control unit can be configured to select the measuring position assigned to the selected stacking device based on the order metadata.

[0059] According to a further embodiment of the proposed device, the device can also be configured to detect the target number of corrugated cardboard sheets in a stack. This makes it possible to compare the actual number of corrugated cardboard sheets detected with the target number. The target number can be part of the order metadata. Thus, the control unit can be configured to receive the target number via the receiving device.

[0060] The control unit can also be configured to detect when the target quantity has been reached. In response to this, the number of corrugated board sheets can be output. Specifically, the control unit can be configured to send a control signal to the stacking unit, prompting it to transport the completed stack. Furthermore, the control unit can be configured to generate a stack telegram that includes, among other things, the number of sheets.

[0061] According to a further embodiment of the proposed device, the detection unit can be configured to detect stack height. In particular, the stack height can be detected using the same device that also detects surface modulation. The stack height can, for example, be used as a control variable for regulating the lowering speed of lifting tables. This can reduce costs and increase the reliability of the corrugated board production line.

[0062] According to a further embodiment of the proposed device, the device can be configured to regulate the lowering speed of the lifting table based on the stack height. For this purpose, the control unit can be connected to a stacking device of the stacking tray, in particular to the lifting table of the stacking device, and configured to readjust the lowering speed of the lifting table.

[0063] Of course, the proposed device can be set up to carry out the proposed procedure.

[0064] The aforementioned task is also solved by a computer program. The proposed computer program comprises machine-readable instructions that, upon execution, cause the control unit of the proposed device to carry out the proposed method.

[0065] Furthermore, the aforementioned task is also solved by a corrugated board plant for the production of corrugated board laminated on at least one side using the proposed device.

[0066] The proposed statements regarding the advantages and possible design of the proposed method apply analogously to the proposed device, the proposed computer program product and the proposed corrugated board plant.

[0067] The attached figures illustrate possible implementation variants of the proposed solution.

[0068] This shows:

[0069] Figure 1 shows a schematic representation of a corrugated board plant with a first embodiment of the proposed device,

[0070] Figure 2 shows a schematic representation of a section through a scale stream including a representation of a surface modulation detected by a discrete distance measurement.

[0071] Figure 3 shows a conveyor belt, a lifting table and a variant embodiment of the proposed device arranged below the conveyor belt.

[0072] Figure 4 shows a representation of a lifting table controlled by a variant of the proposed device.

[0073] Figure 5 shows a section of a schematic representation of a dry end with two stacking devices, and

[0074] Figures 6 to 10 show flowcharts of various embodiments of the proposed method. Figure 1 shows a corrugated board machine 100 for producing corrugated board 109 laminated on at least one side, equipped with an embodiment of the proposed device 200 for detecting a number of corrugated board sheets 109. The device 200 comprises a detection device 210 for detecting surface modulation of the shingle stream and a control unit 230 connected to the detection device 210 and an output device 220. The control unit 230 is configured to detect surface modulation via the detection device 210, determine the number of corrugated board sheets 109, and output the number via the output device 220.

[0075] For example, the output can be accompanied by a visual and / or audible signal, which informs the operator about the number of 109 corrugated cardboard sheets in a stack. This can enable the targeted termination of a stacking process or the allocation of a specific number of stacked 109 corrugated cardboard sheets to a particular stack.

[0076] Alternatively or additionally, the output of the quantity can include sending a control signal to a monitoring device or a control unit, e.g., a stacking tray 190. This allows a stacking process to be controlled. The control can, in particular, include ending the stacking process and assigning the number of stacked corrugated board sheets 109 to the stack. Specifically, the output can include automatically generating a stack telegram containing the number of corrugated board sheets 109 determined based on the surface modulation 214. After the stack has been transported out, the stack telegram can be transmitted to a predetermined recipient, in particular a production monitoring system or a customer-side system.

[0077] In the corrugated board machine 100 shown in Figure 1, two unwinding devices 101, 102 are provided for two material webs 104, 105 to feed the material webs 104, 105, typically made of paper, to a first single-sided machine 110, for example, in the form of a so-called "single facer". A second material web 105 is guided between two corrugating rollers 116, 117 of the first single-sided machine 110. The pair of corrugating rollers 116, 117 creates a corrugation in the second material web 105, thus producing a corrugated layer from the second material web 105, which – after passing a gluing device 114 of the first single-sided machine 110 – is bonded to the first material web 104 by a pressure device 112. A single-sided corrugated board web 107 is provided at the output of the first single-sided machine 110.This corrugated board web 107 is transported via a (high) transport device to a bridge 120 of the corrugated board plant 100 for further processing.

[0078] In the further manufacturing process, the corrugated board web 107 is fed along a conveying direction 124 to a preheating unit 140. This preheating unit 140 is also passed through by a third material web 106. This third material web 106 is supplied by a separate unwinding device 103 and, if necessary, printed by a printing unit 130 before entering the preheating unit 140.

[0079] After passing through the preheating unit 140, one of the webs 106, 107 is coated with glue in a gluing unit 150 equipped with a glue dispenser. In the subsequent manufacturing process, the glued corrugated board web 107 is then bonded to the third material web 106 in a pressure unit 160. For this purpose, the pressure unit 160 can include one or more heating plates, particularly when using conventional starch glue to bond the corrugated board web 107 and the material web 106. The corrugated board web 107 and the third material web 106 are pressed together, for example, by a motor-driven, endless pressure belt guided by guide rollers. The pressure unit 160 can be configured as a tension and heating section.

[0080] In the embodiment of a corrugated board machine 100 shown in Figure 1, the pressure unit 160 produces a single-wall corrugated board, which is then fed to a longitudinal cutting or creasing unit 170 of the corrugated board machine 100 in the further manufacturing process. The longitudinal cutting or creasing unit 170 cuts the continuous single-wall corrugated board web lengthwise.

[0081] Subsequently, a further cutting takes place in a cross-cutting unit 180 to provide corrugated board in the form of sheets 109, which can be processed further, from the continuous corrugated board web. These sheets 109 are conveyed via a conveyor belt 122 of the corrugated board plant 100 of Figure 1 to a stacking tray 190 equipped with at least one stacking device 191. From the stacking tray 190, the corrugated board sheets 109 can be transported away in stacks.

[0082] The detection device 210 of the proposed device shown in Figure 1

[0083] Device 200 is arranged along a vertical spatial direction below the conveyor belt 122 and at one end section of the conveyor belt 122 facing the stacking device 191.

[0084] In alternative configurations that deviate from this, it is also conceivable and possible for the detection device 210 to be arranged differently along the conveying direction 124 or along the vertical spatial direction, as long as the detection device 210 is set up at the respective location to detect the surface modulation of the shingle stream of corrugated board sheets 109. For example, an arrangement above the conveyor belt 122 or above a lifting table of the at least one stacking device 191 is also possible.

[0085] For example, the detection device 210 can be a laser-equipped sensor for distance measurement, which is configured to detect a distance of a surface facing the sensor relative to the sensor with time resolution.

[0086] Figure 2 shows exemplary measured values ​​of a distance s(i) (dotted line) for various support points / , which describe a surface modulation 214 of a scale stream, i.e., a multitude of overlapping corrugated cardboard sheets (hatched areas) 109, for a point-like measuring area. In the example of time-resolved distance measurement, the support points / can represent different points in time. Accordingly, the corrugated cardboard sheets 109, schematically depicted in cross-section, represent a scale stream as it is transported over time through a point-like measuring area of ​​the detection device 210. The scale stream exhibits a non-uniform arrangement of corrugated cardboard sheets 109, such as can occur, for example, as a result of sampling. Consequently, the surface modulation 214 of the scale stream is also irregular, meaning that characteristic features in the surface modulation 214 do not show a periodic pattern.Such characteristic features include, for example, the local maxima of the surface modulation 214 at the support points n1, n2, ..., n7. These maxima differ partly in height, i.e., in the values ​​s(n1), s(n2), ..., s(n7), but also in the distance between adjacent maxima, i.e., n2-n1, n3-n2, ..., n7-n6. Each of the local maxima is associated with a bump 216 in the flux flow, so that the number of corrugated cardboard sheets 109 can be determined by counting the number of bumps 216. In the example of the time-resolved measurement with i=t, the flux flow can thus be determined based on the number of bumps 216 that pass through the measuring area per unit of time.Taking into account the distance between the measuring area and the stacking device 191, a time (retardation) can be determined, based on the speed of the conveyor belt 122, that a point on the conveyor belt 122 needs to travel from the location where the arc flow is detected to the stacking device 191. The arc flow detected at any given time thus defines the number of corrugated board sheets 109 arriving at the stacking device 191 with this retardation.

[0087] Figure 3 shows such a stacking device 191 with a height-adjustable lifting table 194. A stack of corrugated cardboard sheets 109 with a stack height 197 is arranged on the lifting table 194. A continuous stream of further corrugated cardboard sheets 109 is transported to the lifting table 194 via a conveyor belt 122. The transported corrugated cardboard sheets 109 run onto a surface of the existing stack that lies along a vertical direction and are stopped on this surface by a format stop 198 of the stacking device 191. This arranges the corrugated cardboard sheets 109 on the existing stack, while the lifting table 194 lowers along an adjustment direction 196.

[0088] At an end section of the conveyor belt 122 facing the lifting table 194, a detection device 210 of the proposed device 200 is arranged below the conveyor belt 122. This device detects the surface modulation 214 of the lower surface of the flux. The detection device 210 transmits the surface modulation 214 to the control unit 230, which determines a flux from this data and integrates it over time. The control unit 230 is thus configured to determine, at any given time, the number of corrugated board sheets 109 that have passed through the measuring range of the detection device 210. By taking into account the retardation, i.e. the delay with which the corrugated cardboard sheets 109 reach the stack, the control unit 230 determines the number of stacked corrugated cardboard sheets 109. The control unit 230 outputs the number of stacked corrugated cardboard sheets 109 via the output device 220 connected to the control unit 230.

[0089] In alternative embodiments, the detection device can also be configured to detect the stack height 197. In particular, the stack height 197 can be detected with a detection device that also detects the surface modulation 214.

[0090] Figure 4 shows the lifting table 194 and the conveyor belt 122 from Figure 3 with a further embodiment of the proposed device 200, in which a detection device 211 is also configured to detect the stack height 197. For this purpose, the detection device 211 is arranged above the lifting table 194. The adjustment of the lifting table 194 along the adjustment direction 196 is thus included in the distance measurements by the detection device 211. For example, the stack height 197 can be calculated by integrating the height differences in the direction of adjustment 196.

[0091] The embodiment shown in Figure 4 is configured not only to detect the number of corrugated board sheets 109 but also to control the lifting table 194 based on the stack height 197. For this purpose, the control unit 230 is connected to an output device 220, which in turn is connected to the electronically controlled lifting table 194 and configured to adjust the lowering speed of the lifting table 194 based on the stack height. The control unit 230 is configured to increase or decrease the lowering speed of the lifting table 194 via the output device 220 based on the detected stack height 197.

[0092] According to a further embodiment, the surface modulation 214 of a shingle stream can be detected in a multitude of measuring ranges. This can, in particular, make it possible to detect surface modulations 214 of divided shingle streams that are fed to different stacking devices directly in front of or above a lifting table.

[0093] Figure 5 shows a section of a dry end of a two-level corrugated board machine 100. The longitudinally cut corrugated board web is split into two partial corrugated board webs 108 via a diverter 174 and transported to different levels. In a cross-cutting unit 180, the partial corrugated board webs 108 are each cut transversely and fed to the stacking tray 190 via an upper conveyor belt 122 and a lower conveyor belt 123. The stacking tray 190 is equipped with two stacking devices 191 and 192, each of which is in turn equipped with a height-adjustable lifting table 194 and 195, respectively.

[0094] Below the conveyor belts 122, 123, there is a detection device 210, 212 for detecting the surface modulation 214 of each shingle stream. Both detection devices 210, 212 are connected to the control unit 230, which is configured to determine the number of corrugated board sheets 109 stacked in the first stacking device 191 and the number of corrugated board sheets 109 stacked in the second stacking device 192 and to output this information via the output device 220 connected to the control unit 230.

[0095] In an alternative embodiment, the device 200 can also be configured with at least one detection unit movable along the corrugated board system 100 for detecting surface modulation at various measuring positions 100. For example, the at least one detection unit can be externally actuated to move into a selected measuring position from a plurality of possible positions. Accordingly, the proposed device 200 can be configured with an electronically controlled adjustment device, whereby the at least one detection unit can be adjusted between at least two different measuring positions along the length of the corrugated board 100 via the adjustment device.

[0096] Figures 6 to 10 show the processes of different embodiments of the proposed method.

[0097] As shown in Figure 6, the proposed method for detecting a number of corrugated sheets 109 in a stack comprises at least a sensorial detection of a surface modulation 214 of a shingle stream, a determination of the number of corrugated sheets 109 based on the detected surface modulation 214, and an output of the number.

[0098] The dispensing of a specific number of 109 corrugated cardboard sheets can be indicated by an analog and / or digital signal. For example, the dispensing can be indicated by a visual and / or audible signal, informing operators of the number of 109 corrugated cardboard sheets in a stack. This can enable them to selectively stop a stacking operation or to assign a specific number of stacked 109 corrugated cardboard sheets to a particular stack.

[0099] Alternatively or additionally, the output of the quantity can include sending a control signal to a monitoring device or a control unit, e.g., the stacking tray 190. This allows a stacking process to be controlled. The control can, in particular, include ending the stacking process and assigning the number of stacked corrugated board sheets 109 to the stack. Specifically, the output can include automatically generating a stack telegram containing the number of corrugated board sheets 109 determined based on the surface modulation 214. After the stack has been transported out, the stack telegram can be transmitted to a predetermined recipient, in particular to a production monitoring system or to a customer-side system.

[0100] To determine the number of corrugated cardboard sheets 109, joints 216 of the scaled corrugated cardboard sheets 109 can be identified in the surface modulation 214.

[0101] Figure 7 shows an embodiment of the proposed method, in which impacts 216 in the shingle stream are first identified based on the sensor-detected surface modulation 214. Based on the number of impacts 216 of the shingled corrugated sheets 109 passing a predetermined location per unit of time, a sheet flow is then determined, i.e., the number of corrugated sheets 109 transported to a stacking tray 190 per unit of time. From the sheet flow, integration over a stacking time determines how many corrugated sheets 109 have been arranged on the stack. This yields the number of corrugated sheets 109 in a stack, which is subsequently dispensed.

[0102] In other embodiments, it is possible and conceivable to compare the number of corrugated cardboard sheets (109) on the stack with a target number.

[0103] Figure 8 illustrates one possible implementation variant. First, a target number of sheets for the stack is determined. Then, analogous to the implementation variant shown in Figure 7, the number of already stacked corrugated sheets 109 is determined by detecting the surface modulation 214 of the flux flow and integrating the flux flow. Continuously or repeatedly, e.g., after each integration step, it is checked whether the number of already stacked corrugated sheets 109 is less than the target number. If this is the case, the integration is continued and the condition is checked again. As soon as the number of stacked corrugated sheets 109 is equal to or greater than the target number, the stack is removed, thus ending the stacking process. This can be done automatically, for example, by sending a corresponding signal to the stacking device 191, 192.In this version, the stacking time is therefore not a predetermined constant, but rather the time required to produce a stack with the target number of stacked corrugated cardboard sheets (109).

[0104] In addition to completing the stacking process and transporting the stack, a stack telegram can also be generated and sent to a predetermined receiver, such as a computer or a storage unit. The arc current determined within the process sequence shown in Figure 7 can also be used to control a lifting table 194, 195 or a stacking device 191, 192.

[0105] Figure 9 shows a variant embodiment in which the lowering speed of the lifting table 194, 195 is determined such that the lowering speed is proportional to the number of corrugated board sheets 109 arriving at the lifting table 194, 195. The number of corrugated board sheets 109 arriving at the lifting table 194, 195 corresponds to the sheet flow taking into account the retardation.

[0106] In alternative embodiments, relationships other than proportional, i.e. linear, between the sinking speed and the arc current are conceivable and possible.

[0107] Furthermore, the lowering speed of the lifting table can also be regulated within the framework of the proposed procedure.

[0108] Figure 10 shows one possible embodiment. In this embodiment, analogous to the process in Figure 7, a surface modulation 214 is detected, and based on this, the number of corrugated board sheets 109 is determined and output. In addition, the process shown in Figure 10 also detects the stack height 197 of the already stacked corrugated board sheets 109. The stack height 197 is used to adjust the lowering speed of the lifting table 194. This means that, based on the stack height 197, an initial value of the lowering speed is increased or decreased, for example, to maintain a constant drop height derived from the stack height 197. The initial value of the lowering speed can be, for example, a constant value, a value dependent on the conveyor belt speed, or, as in Figure 9, a value dependent on the sheet flow.

[0109] The proposed solution is not limited to the embodiments discussed in detail here. Rather, the proposed solution encompasses any combination of features from the discussed embodiments, provided that these can be combined in a feasible manner by those skilled in the art. List of reference symbols

[0110] 100 corrugated board plants

[0111] 101, 102, 103 Roll-off device

[0112] 104, 105, 106 Material railway

[0113] 107, 108 Corrugated cardboard

[0114] 109 Corrugated cardboard / Corrugated cardboard sheets

[0115] 110 Single-sided machine

[0116] 112 Pressing device

[0117] 114 Gluing device

[0118] 116, 117 Grooved roller

[0119] 120 Bridge

[0120] 122, 123 Conveyor belt

[0121] 124 Direction of conveyance

[0122] 130 printer unit

[0123] 140 Preheating unit

[0124] 150 glue units (glue assembly)

[0125] 160 pressure unit (train section)

[0126] 170 longitudinal cutting unit / grooving unit

[0127] 174 Switch

[0128] 180 cross-cutting unit

[0129] 190 stacking tray

[0130] 191, 192 Stacking device

[0131] 194, 195 Lifting table

[0132] 196 Adjustment direction

[0133] 197 stack height

[0134] 198 Format stop

[0135] 200 Device for recording the number of sheets

[0136] 210, 211, 212 Recording device

[0137] 214 Surface modulation

[0138] 216 impact

[0139] 220 Output device

[0140] 230 control unit

Claims

Patent claims 1. Method for detecting a number of corrugated board sheets (109) in a stack, comprising: sensorial detection of a surface modulation (214) of a shingle stream, Determining the number of corrugated cardboard sheets (109) based on the recorded surface modulation (214), and Output of the number of corrugated cardboard sheets.

2. Method according to claim 1, characterized in that the surface modulation (214) is carried out with a time-resolved distance measurement from a reference point to a measuring area on the surface of the scale stream.

3. Method according to claim 1 or 2, characterized in that, to determine the number of corrugated cardboard sheets (109), joints of the scaled corrugated cardboard sheets (109) in the surface modulation (214) are identified.

4. Method according to one of claims 1 to 3, characterized in that an arc current is determined based on a number of impacts of the shingled corrugated sheets (109) passing a predetermined location per unit of time.

5. Method according to claim 4, characterized in that the number of corrugated cardboard sheets (109) in a stack is determined by temporal integration of the sheet flow.

6. Method according to a preceding claim, characterized in that a surface modulation (214) of a scale stream is detected in a plurality of measuring ranges.

7. Method according to a preceding claim, characterized in that when the detected number of corrugated board sheets (109) corresponds to a target number, the stack is transported out.

8. Method according to a preceding claim, characterized in that a stack height (197) is detected.

9. Method according to claim 8, characterized in that a lowering speed of the lifting table (194, 195) is controlled based on the stack height (197).

10. Device (200) for detecting a number of corrugated board sheets (109) in a stack, comprising: at least one detection device (210, 211, 212) for detecting a surface modulation (214) of a shingle stream, an output device (220) for dispensing a number of corrugated board sheets (109), and a control unit (230) connected to the at least one detection device (210, 211, 212) and the output device (220), which is configured to determine a number of corrugated board sheets (109) based on the detected surface modulation (214) and to dispense them via the output device (220).

11. Device (200) according to claim 10, characterized in that the at least one detection device (210, 211 , 212) is equipped with a sensor designed for distance measurement.

12. Device (200) according to claim 10 or 11, characterized in that the at least one detection device (210, 211, 212) is configured to measure a surface modulation (214) in different measuring ranges.

13. Device (200) according to one of claims 10 to 12, characterized in that the device (200) is configured to carry out a method according to one of claims 1 to 9.

14. Computer program product comprising machine-readable instructions which cause the control unit (230) of a device (200) according to one of claims 10 to 13 to carry out a method according to one of claims 1 to 9.

15. Corrugated board plant (100) for the production of corrugated board laminated on at least one side with a device (200) according to one of claims 10 to 13.

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