Corrugator

Abstract

The invention relates to a corrugator which comprises a corrugated-board production device (1) for producing a corrugated-board web (2) which is laminated on one side and which has a flat web (7) and a corrugated web (10) adhesively bonded thereto. The corrugator also comprises an adhesive-bond-testing device for testing an adhesive bond between the flat web (7) and the corrugated web (10). The adhesive-bond-testing device comprises a detection apparatus (41) for detecting the adhesive bond in the corrugated-board web (2, 26), which is laminated on one side, between the flat web (7) and the corrugated web (10) at a detection-apparatus test frequency. The detection-apparatus test frequency is selected according to the design of the corrugated-board web (2) which is laminated on one side. In addition, the adhesive-bond-testing device has an adhesive-bond-evaluation apparatus (42) which is connected for signalling purposes to the detection apparatus (41) and receives detection signals from the latter, which signals are representative of the adhesive bond in the corrugated-board web (2), which is laminated on one side, between the flat web (7) and the corrugated web (10).

Description

[0001] Corrugated board plant

[0002] The invention relates to a corrugated board production line. Furthermore, it is directed to a method for producing corrugated board.

[0003] During the production of corrugated board, a corrugated sheet is typically formed and bonded to a cover sheet to form a single-sided laminated corrugated board sheet. The bonding of the corrugated sheet and cover sheet to one another is a key factor in the quality of the finished corrugated board. Various measures are known for testing the bonding quality between the cover sheet and corrugated sheet. For example, sampling is carried out, which, however, entails a significant time delay until results on the bonding quality are available. Inline testing methods through obvious prior use are also known, which are based, for example, on an imaging evaluation of the wave formation of the single-sided laminated corrugated board sheet or on empirical testing methods using test waves, such as ultrasonic waves.Imaging often cannot reliably detect a faulty internal bond between the liner and corrugated sheet, for example, due to external deformation of the corrugated board or the single-sided laminated corrugated board. Testing methods using test waves generally only allow for spot testing. Calibrating or adjusting a testing system is generally difficult or time-consuming.

[0004] The invention is based on the object of eliminating the disadvantages of the prior art. In particular, a corrugated board plant is to be provided whose bonding testing device is particularly reliable and user-friendly. A corresponding method is also to be provided. This object is achieved according to the invention by the features specified in independent claims 1 and 15. The core of the invention lies in the detection device, which operates at a detection device test frequency during operation. The detection device test frequency depends on the design, such as geometry, structure, cross-section and / or material, of the single-sided laminated corrugated board web to be tested. It is selected or adjusted accordingly during operation of the detection device. The detection device test frequency to be used or selected preferably lies within a detection device test frequency range during operation.

[0005] For example, the design of the single-faced corrugated board web to be tested is determined, for example, by a sensor device, for the selection / setting of the detection device's test frequency. Alternatively, the design is communicated to the corrugator manually, such as by a system operator. Alternatively, and this is preferred, the corrugator uses information about the production of the single-faced corrugated board web, for example, information related to its design and known to the corrugator for production. The corrugator knows which (single-faced) corrugated board web or flute type is currently being produced.

[0006] It is expedient if the detection device operates contactlessly during operation. It detects the bond directly or indirectly. For example, a direct measurement or indirect measurement of the bond is carried out. For example, at least one value characterizing the bond is measured. The detection device preferably operates while the single-sided laminated corrugated cardboard web is being conveyed. It advantageously operates continuously or cyclically. It is advantageous if the detection device or a main plane of a detection field thereof is oriented perpendicular to the cover web or an adjacent area thereof during operation. Preferably, an angular adjustment of the detection device relative to the cover web is unnecessary. However, other angles between the detection device and the cover web are alternatively possible during operation.

[0007] The detection device advantageously has at least one sensor unit assigned to the single-sided laminated corrugated cardboard web to be tested, which is preferably designed as a transmission sensor unit or transmission measuring unit. Advantageously, the at least one sensor unit comprises at least one transmitter and at least one associated, in particular opposite, receiver arranged at a distance from the transmitter, wherein the single-sided laminated corrugated cardboard web to be tested is located between the at least one transmitter and receiver.

[0008] It is advantageous if the at least one sensor unit of the detection device is designed as an ultrasonic or microwave sensor unit. For example, it can be moved across the width of the single-sided laminated corrugated cardboard web to be tested in order to test the bond across the entire width of the single-sided laminated corrugated cardboard web. Alternatively, for example, several sensor units are arranged next to one another in a width direction of the single-sided laminated corrugated cardboard web to be tested in order to test the bond across the entire width of the single-sided laminated corrugated cardboard web. It is expedient if an excitation signal is sent to the at least one transmitter at each test point, which excitation signal is preferably selected as a transient signal or burst signal, such as a double sine burst signal, with preferably at least two, preferably more, periods. Advantageously, interfering, low-frequency components in the detection signal orin the signal recorded by the receiver is suppressed or filtered out by means of a high-pass filter.

[0009] The bonding evaluation device is, for example, arranged adjacent to the detection device or at a distance from it. It is, for example, part of a corrugated board plant operating unit such as a corrugated board plant control unit or is at least temporarily in signal communication with it. The bonding evaluation device is, for example, electrical or electronic in nature. It is, for example, permanently in signal communication with the detection device or only during signal transmission. The signal connection between the bonding evaluation device and the detection device is wireless or wired. Based on the received detection signals, the bonding evaluation device determines, for example, the bond or its bonding quality. For example, a deviation from a target bonding quality in the single-sided laminated corrugated board web can be detected using the bonding evaluation device.In particular, good and bad bonding can be reliably and easily distinguished from one another.

[0010] The detection signals are preferably electrical. They depend on the bond between the liner and the corrugated sheet in the single-sided laminated corrugated board web to be tested, in particular on the bond quality. The bond testing device preferably operates automatically. It preferably uses a data processing algorithm. The data processing algorithm is advantageously capable of predicting the bond quality. Exactly one sensor unit is sufficient to predict the bond quality.

[0011] The single-sided laminated corrugated cardboard web is / is preferably conveyed in a main conveying direction during the gluing process, advantageously continuously. It is advantageous if one corrugation of the corrugated web extends perpendicular to the main conveying direction of the single-sided laminated corrugated cardboard web.

[0012] It is advantageous if, in a target state of the single-sided laminated corrugated cardboard web, the corrugated web is glued to the cover web via its corrugation troughs arranged adjacent to the cover web. Corresponding inner bonding or gluing areas are present there. In a target state, the bonding is preferably linear between the cover web and a corrugation trough. According to the target state, the bonding lines in the single-sided laminated corrugated cardboard web are arranged equidistant from one another, of equal width, uniform width, parallel to one another and / or uninterrupted in the width direction of the single-sided laminated corrugated cardboard web. Bonding is preferably carried out using adhesive or glue, such as starch glue.

[0013] It is advantageous if the single-sided corrugated board web is continuous. It is preferably (essentially) made of cardboard, paper, or the like. The cover sheet and the corrugated board each consist of cardboard, paper, or the like. The cover sheet is advantageously a smooth sheet. The single-sided corrugated board web contains air, particularly ambient air. This is primarily due to the three-dimensional corrugated board.

[0014] It is advisable to individually cut out or eject a detected defective area of ​​the single-sided laminated corrugated board web from the corrugator.

[0015] The corrugated board production device preferably comprises a corrugating device for corrugating a material web to form the corrugated web or corrugated web. It also advantageously has a glue application device for applying glue to the corrugated web. It is advantageous if the corrugated board production device further comprises a pressing device for pressing the cover sheet against the glued corrugated web to form the single-sided laminated corrugated board web. In the single-sided laminated corrugated board web, the cover sheet and corrugated web are advantageously glued or bonded together in layers.

[0016] The single-sided laminated corrugated board web is preferably used to produce a double-sided laminated corrugated board web, for example, three-layer, five-layer, or seven-layer. The corrugator line then has more than one corrugated board production device for the production of a five-layer or seven-layer corrugated board web.

[0017] It is expedient for the corrugated board plant to have an unwinding device for unwinding the cover sheet. It is advantageous if it also has an unwinding device for unwinding the corrugated sheet or a material web to form the corrugated sheet. Preferably, the corrugated board plant also includes a liner unwinding device for unwinding a liner. Furthermore, the corrugated board plant preferably has a gluing unit for applying glue to the corrugated board of the single-sided laminated corrugated board web.

[0018] It is advantageous if the corrugated board plant also comprises a connecting device for joining the glued single-sided laminated corrugated board web and the laminated web to form a double-sided laminated corrugated board web.

[0019] Preferably, the corrugated board plant further comprises a longitudinal cutting and creasing device for longitudinal cutting and creasing the double-sided laminated corrugated board web.

[0020] The corrugated board plant advantageously also includes a cross-cutting device for cross-cutting the double-sided laminated corrugated board web or partial webs thereof in order to form corrugated board sheets.

[0021] It is useful if the corrugated cardboard sheets can be stacked in a stacking device of the corrugator.

[0022] Further advantageous embodiments of the invention are specified in the subclaims.

[0023] The embodiment according to subclaim 2 results in a functionally reliable bonding test device. The test waves are preferably sound waves, in particular ultrasonic waves, or electromagnetic waves, such as microwaves. The phase velocity or propagation velocity of the test waves depends on a wavelength and the detection device test frequency. According to subclaim 3, the detection device test frequency is selected depending on the design of the corrugated sheet, such as its geometry, shape, cross-section, wave design / type, such as wave pitch, wave height, and / or material of the single-sided laminated corrugated cardboard sheet to be tested. According to the invention, it was recognized that the design of the corrugated sheet has a (significant) influence on the detection device test frequency. Corrugated sheets differ from one another, for example, in their wave type.The flute of the single-sided laminated corrugated board web to be tested has, for example, a K-flute, A-flute (coarse flute), C-flute (medium flute), B-flute (fine flute), D-flute (fine flute), E-flute (fine or micro flute), F-flute (mini flute), G-flute (mini flute) or N-flute (mini flute).

[0024] According to subclaim 5, the detection device test frequency is selected depending on the wave height of the corrugated sheet of the single-sided laminated corrugated cardboard sheet to be tested. A wave height is preferably understood to be the vertical distance between the wave peak / peak, in particular an upper / outer region thereof, and the wave trough, in particular a lower / outer region thereof, in the corrugated sheet.

[0025] The lower test frequency limit according to dependent claim 6 is preferably dependent on the single-sided laminated corrugated board web to be tested, in particular on its corrugated web, in particular its flute design, in particular its flute height. If the detection device test frequency is below the lower test frequency limit, problems arise when testing the bond, for example, in the detection of the single-sided laminated corrugated board web to be tested. In particular, problems then arise when testing the bond in the single-sided laminated corrugated board web to be tested between the cover web and the corrugated web.

[0026] The upper test frequency limit according to dependent claim 7 is advantageously dependent on the single-sided laminated corrugated cardboard web to be tested, in particular on its corrugated web, in particular its wave design, in particular its wave height. If the detection device test frequency is above the upper test frequency limit, irregularities may occur in an image obtained showing the bond when testing the bond.

[0027] If the detection device test frequency is / is selected too high for the test, signals from the material of the single-sided laminated corrugated cardboard web under test will dominate. The wavelength is refracted, for example, in individual layers of the single-sided laminated corrugated cardboard web. The range above the upper test frequency limit should be avoided, as refraction phenomena dominate there. The resulting image of the bond will be irregular.

[0028] The detection device test frequency must not be selected too low. For example, it is selected such that refraction is detectable in at least one cavity of the single-sided corrugated cardboard web to be tested. The detection device test frequency is preferably also selected such that the detection device is capable of completely radiating or penetrating the single-sided corrugated cardboard web to be tested. It is advantageously selected such that refractions occur in the single-sided corrugated cardboard web, in particular its corrugated web, particularly in its wave crests. The resulting frequency spectrum is preferably sharp or defined.

[0029] The detection device operating according to subclaim 8 is particularly reliable in operation. Bonding defects can be reliably and easily detected. The material of the single-sided laminated corrugated cardboard web to be tested is, in particular, cardboard, paper, or the like.

[0030] The statements relating to sub-claim 8 apply essentially analogously to sub-claim 9. The air is located in particular in the single-sided laminated corrugated cardboard web, in particular adjacent to its corrugated web.

[0031] The detection signals according to dependent claim 10 are, preferably always, identical when there is no bonding defect in the single-sided laminated corrugated cardboard web to be tested. They are identical, in particular, with regard to signal amplitude, signal shape, and / or signal propagation time. It is expedient if the detection field of the detection device is capable of detecting more than one wave crest at a time during the test.

[0032] The embodiment according to subclaim 11 is user-friendly and resistant to operating errors. Calibration of the detection device is preferably unnecessary.

[0033] The design according to subclaim 12 allows for reliable detection of a bonding error. The group comprises, for example, between two and ten, preferably between three and eight, previous detection values. In particular, an error can be easily or reliably detected by an outlier detection value.

[0034] The design according to subclaim 13 is very reliable in its function.

[0035] The corrugated board system according to subclaim 14 is efficient. It preferably forms a controlled system. For example, the amount of glue used for bonding the cover sheet and the corrugated sheet can be adjusted and controlled accordingly. Corrugated board waste can thus be avoided or reduced. It is expedient if the bonding testing device is located (immediately) adjacent to the corrugated board production device, such as its corrugating device, in order to react as quickly as possible to detected bonding defects.

[0036] Subclaims 2 to 14 also relate to advantageous embodiments of the method according to independent claim 15.

[0037] The terms “upstream”, “downstream”, “upstream”, “downstream” or the like used here refer in particular to the main conveying direction of the cover sheet, corrugated sheet or single-sided laminated corrugated board sheet.

[0038] The indefinite articles specified in the claims are not to be understood as limiting the number. For example, the corrugator may have more than one corrugator and / or bonding tester. Preferred embodiments of the invention are described below by way of example with reference to the accompanying drawings. In the drawings:

[0039] Fig. 1 is a partial view of a corrugated board plant according to the invention,

[0040] Fig. 2 essentially shows a schematic enlarged section of the corrugated board plant illustrated in Fig. 1, which mainly illustrates a corrugated board manufacturing device for producing a single-sided laminated corrugated board web and an adhesive testing device,

[0041] Fig. 3 is a simplified view showing the structure of a single-sided laminated corrugated board web to be tested,

[0042] Fig. 4 is a simplified enlarged view of the detection device shown in Fig. 2,

[0043] Fig. 5 is a view corresponding to Fig. 4 of an alternative detection device, and

[0044] Fig. 6 a simplified view of another alternative detection device

[0045] Referring first to Fig. 1, a corrugated board plant, which is only partially shown there, comprises a first corrugated board manufacturing device 1 for producing a one-sidedly laminated, endless first corrugated board web 2. A first cover web splicing device 3 and a first material web splicing device 4 are arranged upstream of the first corrugated board manufacturing device 1.

[0046] The first cover web splicing device 3 comprises a first unwinding unit 5 for unwinding a finite first cover web from a first cover web roll and a second unwinding unit 6 for unwinding a finite second cover web from a second cover web roll. The finite first cover web and finite second cover web are connected to one another to provide an endless first cover web 7 by means of a connecting and cutting unit (not shown) of the first cover web splicing device 3.

[0047] The first material web splicing device 4 is designed correspondingly to the first cover web splicing device 3. This device comprises a third unwinding unit 8 for unwinding a finite first material web from a first material web roll and a fourth unwinding unit 9 for unwinding a finite second material web from a second material web roll. The finite first material web and finite second material web are joined together to provide an endless first material web 10 by means of a connecting and cutting unit (not shown) of the first material web splicing device 4.

[0048] The endless first cover web 7 is fed to the first corrugated board production device 1 via a first heating roller 11, while the endless first material web 10 is fed to the first corrugated board production device 1 via a first deflection roller 12. The first corrugated board production device 1 comprises a corrugating roller device with a first corrugating roller 13 and a second corrugating roller 14 (see also Fig. 2) for producing a corrugated, endless first corrugated web from the endless first material web 10. The corrugating rollers 13, 14 form a corrugating gap for passing and corrugating the endless first material web 10. The axes of rotation of the corrugating rollers 13, 14 run parallel to one another and horizontally.

[0049] To join the endless first cover web 7 to the endless corrugated first material web or corrugated web 10 to form the one-sidedly laminated, endless first corrugated board web 2, the first corrugated board manufacturing device 1 has a glue application device 15, which preferably comprises a glue metering roller 16, a glue container 17, and a glue application roller 18. To feed and apply glue to the endless first corrugated web 10, the glue application roller 18 forms a gluing gap 19 with the first corrugating roller 13. Glue located in the glue container 17 is applied via the glue application roller 18 to adjacent wave crests or wave peaks of the corrugation of the endless first corrugated web 10. The glue metering roller 16 is arranged adjacent to the glue application roller 18 and serves to form a uniform glue layer on the glue application roller 18.

[0050] The endless first cover sheet 7 is then joined to the endless first corrugated sheet 10 provided with glue from the glue container 17 in the first corrugated cardboard manufacturing device 1 to produce the one-sidedly laminated, endless first corrugated cardboard sheet 2.

[0051] To press the endless first cover sheet 7 against the glued, endless first corrugated sheet 10, which in turn rests partially against the first corrugating roller 13, the first corrugated board manufacturing device 1 has a pressing device 20. The pressing device 20 is advantageously designed as a pressing belt device. It is arranged above the first corrugating roller 13. The pressing device 20 has at least two deflection rollers and an endless pressing belt that is guided around the deflection rollers. Alternatively, the pressing device 20 comprises, for example, at least one pressing roller.

[0052] The first corrugating roller 13 engages from below in a space between the laterally outer deflection rollers of the pressing device 20, whereby the pressing belt is deflected by the first corrugating roller 13. The pressing belt presses against the endless first cover web 7, which in turn is pressed against the glued, endless first corrugated web 10 resting against the first corrugating roller 13.

[0053] For intermediate storage and buffering of the one-sidedly laminated, endless, first corrugated cardboard web 2, it is fed via a first overhead transport device 21 to a first storage device 22 of the corrugator, where it forms loops.

[0054] Furthermore, the corrugated board plant here has a second corrugated board production device 23, which is designed correspondingly to the first corrugated board production device 1. The second corrugated board production device 23 is capable of producing a single-sided, endless second corrugated board web 26 from an endless second cover web and an endless second material web. The endless second material web is corrugated.

[0055] The second corrugated board manufacturing device 23 is provided with a second

[0056] Cover web splicing device 24 for providing the endless second cover web and a second material web splicing device 25 for providing the endless second material web are arranged upstream, which are designed correspondingly to the first cover web splicing device 3 and the first material web splicing device 4, respectively.

[0057] The one-sidedly laminated, endless second corrugated board web 26 is fed to a second storage device 27 of the corrugator, where it forms loops. As mentioned, an alternative design without a second corrugated board production device 23 is possible.

[0058] The corrugated board plant also has a lamination web splicing device 28, which comprises a fifth unwinding unit 29 for unwinding a finite first lamination web from a first lamination web roll and a sixth unwinding unit 30 for unwinding a finite second lamination web from a second lamination web roll. The finite first lamination web and the finite second lamination web are joined together to provide an endless lamination web 31 by means of a connecting and cutting unit (not shown) of the lamination web splicing device 28.

[0059] Downstream of the storage devices 22, 27 and the lamination web splicing device 28, the corrugated board system has a preheating device 32, which has three preheating rollers 33, 34, 35 arranged one above the other. The single-sided, endless corrugated board webs 2, 26 and the endless lamination web 31 are fed to the preheating device 32, which wrap around the respective preheating rollers 33, 34, and 35, respectively, and are thereby heated.

[0060] Downstream of the preheating device 32, the corrugator has a gluing unit (not shown) with gluing rollers that are partially immersed in a respective glue bath. The single-sided, endless first corrugated board web 2, with its corrugated web 10, is in contact with a first gluing roller, so that the corrugation of this corrugated web 10 is provided with glue from the associated first glue bath. The single-sided, endless second material web 26, with its corrugated web, is in contact with a second gluing roller, so that the corrugation of this corrugated web is provided with glue from the associated second glue bath.

[0061] Downstream of the gluing unit, the corrugator has a connecting device (not shown) designed as a heating / pressing device and comprising a horizontally extending heating table. Adjacent to the heating table is an endless pressing belt guided around guide rollers. A pressing gap is formed between the pressing belt and the heating table, through which the single-sided, endless corrugated board webs 2, 26 and the endless lamination web 31 are guided, forming an endless, double-sided corrugated board web (not shown). The endless, double-sided corrugated board web is five times longer in this case.

[0062] Downstream of the connecting device, the corrugator comprises a slitting and creasing device (not shown) for slitting and creasing the endless, double-sided laminated corrugated cardboard web. The slitting and creasing device has creasing stations and longitudinal cutting stations arranged one behind the other. The creasing stations each have creasing tools arranged in pairs one above the other, between which the double-sided laminated, endless corrugated cardboard web is passed. The longitudinal cutting stations each have rotary-driven knives that can be brought into engagement with the double-sided laminated, endless corrugated cardboard web to sever it lengthwise. In the slitting and creasing device, endless partial webs can be produced from the double-sided laminated, endless corrugated cardboard web, which initially run next to each other.

[0063] Downstream of the slitting and creasing device, the corrugator has a switch (not shown) to convey the partial webs of the double-sided laminated, endless corrugated board web to different levels.

[0064] Downstream of the switch, the corrugator has a cross-cutting device with stacked cross-cutting units. Each cross-cutting unit comprises two paired cutter bars with radially projecting cutter bars. The cutter bars of the cutter bars of a cross-cutting unit work together to cross-cut a partial web. Corrugated board sheets are thus produced from the partial webs.

[0065] Each cross-cutting device is followed by a conveyor belt device (not shown) to further convey the corrugated cardboard sheets produced from the partial webs.

[0066] Each conveyor belt is followed by a stacking device (not shown). In the stacking devices, the corrugated cardboard sheets can be stacked one on top of the other.

[0067] During corrugated board production, the single-sided, endless first corrugated board web 2 and the single-sided, endless second corrugated board web 26, as well as the endless lamination web 31, are conveyed in a main conveying direction 36. The design of the single-sided, endless first corrugated board web 2 is described in more detail below using an example. The single-sided, endless second corrugated board web 26 is designed in a correspondingly analogous manner.

[0068] As mentioned, the one-sided laminated, endless first corrugated cardboard web 2 comprises the endless first cover web 7 and the endless first corrugated web 10, which are bonded to each other by adhesive or glue (see also Fig. 3).

[0069] The corrugation of the endless first corrugated web 10 is regular and runs perpendicular to the main conveying direction 36 as it is conveyed in the corrugator. The endless first corrugated web 10 has alternating wave crests or wave peaks 37 and wave troughs 38. A wave flank 39 extends between a wave crest 37 and an adjacent wave trough 38. The wave crests 37 extend parallel to one another. They also run parallel to the wave troughs 38. The wave crests 37 and wave troughs 38 each extend in the corrugated cardboard plant perpendicular to the main conveying direction 36 or to a longitudinal extent of the one-sidedly laminated, endless first corrugated web 2. They run in the width or transverse direction of the one-sidedly laminated, endless first corrugated cardboard web 2. The one-sidedly laminated, endless first corrugated cardboard web 2 is curved at the wave crests 37 and wave troughs 38.The wave flanks 39, for example, run obliquely to the endless first cover sheet 7.

[0070] In the single-sided, endless first corrugated cardboard web 2, the continuous first corrugated web 10 is adhesively bonded to the continuous first cover web 7 via its troughs 38. The troughs 38 of the single-sided, endless first corrugated cardboard web 2 are arranged adjacent to the continuous first cover web 7. The crests 37, however, are arranged at a distance from the continuous first cover web 7. They are exposed in the single-sided, endless first corrugated cardboard web 2.

[0071] In a desired state of the single-sided, endless first corrugated cardboard web 2, each trough 38 is adhesively connected to the endless first cover sheet 7 via a linear or strip-like adhesive region 40 consisting of adhesive or glue and extending between the endless first cover sheet 7 and the respective trough 38 of the endless first corrugated cardboard web 10 across the entire width of the single-sided, endless first corrugated cardboard web 2. The adhesive regions 40 run parallel and spaced from one another in the width or transverse direction of the single-sided, endless first corrugated cardboard web 2. They extend uninterruptedly along the adjacent trough 38 and have a uniform width and thickness. The adhesive regions 40 are located internally in the single-sided, endless first corrugated cardboard web 2.

[0072] The one-sidedly laminated, endless first corrugated board web 2 or the endless first corrugated web 10 has a uniform flute height WH, which lies between a flute peak 37 and a flute trough 38. It has a uniform flute pitch T.

[0073] A first detection device 41 of a first bonding testing device is arranged downstream of the first corrugated board production device 1 (Fig. 2). The first detection device 41 is assigned to the single-sided, endless first corrugated board web 2 and is arranged adjacent to the first corrugated board production device 1. The first bonding testing device also has a first bonding evaluation device 42 (Fig. 2).

[0074] The first detection device 41 has at least one first sensor unit, which in turn comprises a first transmitter 43 and a first receiver 44 assigned to it. The first transmitter 43 and the first receiver 44 of the respective sensor unit are each spaced apart from the single-sided, endless first corrugated cardboard web 2 to be detected and are arranged (essentially) opposite one another. They are aligned relative to one another and arranged in pairs. The single-sided, endless first corrugated cardboard web 2 is guided between the first transmitter 43 and the first receiver 44 of the respective sensor unit. The first transmitter 43 and the first receiver 44 are oriented perpendicular to the endless first cover web 7 (Figs. 2, 4). In particular, the first transmitter 43 generates a first detection field during operation, the main plane H of which runs perpendicular or vertical to the endless first cover web 7 there.The respective sensor unit is preferably aligned perpendicular to a main plane of the single-sided, endless first corrugated cardboard web 2. The main plane of the single-sided, endless first corrugated cardboard web 2 extends parallel to the endless first cover web 7.

[0075] The first transmitter 43 is here directed toward or assigned to the endless first cover web 7 of the single-sided, endless first corrugated cardboard web 2. Conversely, the first receiver 44 is here directed toward or assigned to the endless first corrugated web 10.

[0076] The first detection device 41 is designed as an ultrasonic detection device, in particular an air-ultrasonic detection device. Accordingly, the first transmitter 43 of the respective sensor unit is an ultrasonic transmitter, while the first receiver 44 of the respective sensor unit is an ultrasonic receiver.

[0077] During operation, the first receiver 43 transmits ultrasonic waves, preferably repeatedly or recurrently, which pass through the conveyed, single-sided, endless first corrugated cardboard web 2, in particular through the endless first cover web 7 and the endless first corrugated web 10, to the opposite first receiver 44 of the respective sensor unit and are thus received by it. The single-sided, endless first corrugated cardboard web 2 is thus completely transduced by ultrasound in its thickness direction. The inner adhesive areas 40 of the single-sided, endless first corrugated cardboard web 2 are also detected. The first detection device 41 operates according to the one-way ultrasound principle.

[0078] During operation, an electrical supply voltage is applied to the first detection device 41. The first detection device 41 operates with a first detection device test frequency, which is preferably selected or set between 90 kHz and 390 kHz depending on the specific design of the single-sided, endless first corrugated cardboard web 2, in particular the flute height WH. In order to be able to cover the entire corrugated cardboard production spectrum, each first sensor unit preferably comprises several, advantageously two, different test head pairs. Single-sided, endless first corrugated cardboard webs 2 with coarse flutes are preferably tested with one test head or a frequency between 90 kHz and 150 kHz. Single-sided, endless first corrugated cardboard webs 2 with fine flutes are tested, for example, with one test head or a frequency between 280 kHz and 390 kHz.The first bonding evaluation device 42 is at least temporarily in signal communication with the first receiver 44 of the respective sensor unit. For example, the first bonding evaluation device 42 is arranged on the associated first receiver 44 or is a component thereof. Alternatively, the first receiver 44 and the first bonding evaluation device 42 are arranged separately from one another.

[0079] The detection of the bonding of the one-sided laminated, endless first corrugated cardboard web 2 is based, for example, on a measurement of an ultrasonic amplitude passing through the one-sided laminated, endless first corrugated cardboard web 2.

[0080] The thicker or denser the single-sided, endless first corrugated cardboard web 2, the lower the proportion of transmitted ultrasound. If the single-sided, endless first corrugated cardboard web 2 is poorly bonded, ultrasound propagation within it is disrupted, and the signal amplitude drops. The shorter the wavelength, the more the signal is disrupted by the internal structure of the single-sided, endless first corrugated cardboard web 2. For example, uneven glue application leads to lower signal amplitudes. The ultrasound signal must penetrate layers of varying stiffness in the single-sided, endless first corrugated cardboard web 2. These different impedances disrupt wave propagation within the single-sided, endless first corrugated cardboard web 2.

[0081] The corresponding detection signals from the first receiver 44 of the respective sensor unit for the tested, single-sided, endless first corrugated cardboard web 2 are fed to the associated first bonding evaluation device 42. The first bonding evaluation device 42 is capable of processing the received detection signals that characterize the single-sided, endless first corrugated cardboard web 2.

[0082] The single-sided, endless first corrugated cardboard web 2 is preferably described as an anisotropic, layered medium for bond testing. Wave propagation can be described, for example, using the Floquet wave theory. Layered media therefore act as mechanical filters. If the signal wavelength is smaller than twice the layer thickness, the medium can no longer be assumed to be homogeneous. Refraction processes occur within the microstructure of the medium. The acquisition test frequency is therefore selected so that it lies below an upper test limit frequency to ensure good sound transmission through the medium.

[0083] It is expedient if information on transmitted energy, signal propagation time and / or signal entropy is extracted or determined from the detection signal in the first bonding evaluation device 42.

[0084] It is advantageous to combine the transmitted energy, signal propagation time, and / or signal entropy to draw conclusions about the bonding or bonding quality in the single-sided, endless first corrugated cardboard web 2. In particular, their relative relationships are used. For determining the signal entropy, an excitation signal preferably has a narrow frequency spectrum. If, for example, the signal undergoes multiple refraction processes during testing, it expands. It becomes more broadband. For example, an uneven application of glue to the single-sided, endless first corrugated cardboard web 2 leads to low signal amplitudes. This is because the signal must penetrate layers of different stiffness. These different impedances disrupt wave propagation in the single-sided, endless first corrugated cardboard web 2.Delaminations in the one-sided laminated, endless first corrugated board web 2 can be reliably detected.

[0085] The bonding test device detects bond lines, wave crests 37, and wave troughs 38 of the single-sided, endless first corrugated cardboard web 2. It is capable of distinguishing them from one another. The data processing algorithm used is capable of distinguishing between bond lines and wave crests 37. To ensure this, it is necessary that refraction processes occur in wave crest 37 during the test. Therefore, the detection device's test frequency during operation is selected to be sufficiently high to enable this.

[0086] The signal-to-noise ratio is generally better the lower the detection device test frequency. The shorter the wavelength, the more sensitive the signal is to interference.

[0087] By conveying the one-sidedly laminated, endless first corrugated cardboard web 2 in the main conveying direction 36 through the stationary first detection device 41, all adhesive areas 40 are detected one after the other.

[0088] A second detection device 47 is configured and arranged in a similar manner. The second detection device 47 of a second bonding testing device is arranged downstream of the second corrugated cardboard production device 23. The second detection device 47 is assigned to the single-sided, endless second corrugated cardboard web 26 and is arranged adjacent to the second corrugated cardboard production device 23. It is operated in a similar manner and is capable of detecting the single-sided, endless second corrugated cardboard web 26. The second bonding testing device is capable of testing the bonding of the single-sided, endless second corrugated cardboard web 26. It comprises a second bonding evaluation device.

[0089] In the alternative embodiment according to Fig. 5, the first transmitter 43 and first receiver 44 of a sensor unit are arranged interchangeably. The first transmitter 43 is here facing or associated with the endless first corrugated web 10 of the single-sided, endless first corrugated cardboard web 2. The first receiver 44 is here facing or associated with the endless first cover web 7 of the single-sided, endless first corrugated cardboard web 2. The function and specific design are the same as in the previous embodiment.

[0090] In the preferred embodiment according to Fig. 6, the detection field generated by the first transmitter 43 always detects two wave troughs 38 arranged next to one another in the main conveying direction 36. In particular, the detection field in the main conveying direction 36 on the one-sidedly laminated, endless first corrugated cardboard web 2 has an extension X that is greater than the wave pitch T. The first transmitter 43 here generates a near detection field 45 and a far detection field 46.

[0091] Combinations of different designs are possible.

Claims

Patent claims 1. Corrugated cardboard plant, a) with a corrugated cardboard production device (1, 23) for producing a single-sided laminated corrugated cardboard web (2, 26) which has a cover web (7) and a corrugated bar (10) glued to it, and b) with a bond testing device for testing a bond in the single-sided laminated corrugated cardboard web (2, 26) between the cover web (7) and the corrugated bar (10), wherein the bond testing device has i) a detection device (41, 47) arranged downstream of the corrugated cardboard production device (1, 23) for detecting the bond in the single-sided laminated corrugated cardboard web (2, 26) to be tested between the cover web (7) and the corrugated bar (10) with a detection device test frequency, wherein the detection device test frequency depends on a configuration of the to be tested, one-sided laminated corrugated cardboard web (2, 26), and ii) a bonding evaluation device (42) which is connected to the detection device (41,47) is at least temporarily in signal communication and receives from it detection signals representative of the bonding in the single-sided laminated corrugated cardboard web (2, 26) to be tested between the cover web (7) and the corrugated web (10).

2. Corrugated cardboard plant according to claim 1, characterized in that the detection device test frequency depends on a phase velocity of test waves of the detection device (41, 47) in the single-sided laminated corrugated cardboard web (2, 26) to be tested.

3. Corrugated cardboard plant according to claim 1 or 2, characterized in that the detection device test frequency is selected depending on a design of the corrugated web (10) of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

4. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device test frequency is selected as a function of a wave design of the corrugated web (10) of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

5. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device test frequency is selected as a function of a wave height (WH) of the corrugated web (10) of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

6. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device test frequency is selected such that it is greater than a lower test limit frequency and breaking processes occur in the corrugated web (10), in particular in at least one detected wave crest (37) of the same, of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

7. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device test frequency is selected such that it is lower than an upper test limit frequency and a The test wave passes through the single-sided laminated corrugated cardboard web (2, 26) to be tested.

8. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device test frequency is selected such that it is smaller than a quotient of a phase velocity of test waves of the detection device (41, 47) in material of the single-sided laminated corrugated cardboard web (2, 26) to be tested and twice a wave height (WH) of the corrugated web (10) of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

9. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device test frequency is selected such that it is greater than a quotient of a phase velocity of test waves of the detection device (41, 47) in air and twice a wave height (WH) of the corrugated web (10) of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

10. Corrugated cardboard plant according to one of the preceding claims, characterized in that the detection device (41, 47) is capable of generating a detection field during operation which jointly detects at least two adjacent wave crests (37) of the corrugated web (10) of the single-sided laminated corrugated cardboard web (2, 26) to be tested.

11. Corrugated board plant according to one of the preceding claims, characterized in that a manual specification of an upper and / or lower error threshold value is omitted.

12. Corrugated cardboard plant according to one of the preceding claims, characterized in that the bonding evaluation device (42) compares a current detection value with a group of previous detection values ​​in order to detect a bonding error.

13. Corrugated cardboard plant according to one of the preceding claims, characterized in that the bonding evaluation device (42) evaluates signal amplitudes, signal propagation times and / or signal shapes of the detection signals for testing the bonding in the single-sided laminated corrugated cardboard web (2, 26) to be tested between the cover web (7) and the corrugated web (10).

14. Corrugated cardboard plant according to one of the preceding claims, characterized by a closed control loop for controlling the corrugated cardboard manufacturing device (1, 23) as a function of the detection signals.

15. A method for producing corrugated cardboard, comprising the steps Producing a single-sided laminated corrugated cardboard web (2, 26) comprising a cover web (7) and a corrugated web (10) glued thereto by means of a corrugated cardboard manufacturing device (1, 23), and testing a bond in the single-sided laminated corrugated cardboard web (2, 26) between the cover web (7) and the corrugated web (10) by means of a bond testing device by — selecting a detection device test frequency depending on the design of the single-sided laminated corrugated cardboard web (2, 26) to be tested, — Detecting the bond in the single-sided laminated corrugated cardboard web (2, 26) to be tested between the cover sheet (7) and the corrugated web (10) by means of a detection device (41, 47) of the bonding testing device arranged downstream of the corrugated cardboard manufacturing device (1, 23) with the detection device test frequency, and - receiving detection signals representative of the bond in the single-sided laminated corrugated cardboard web (2, 26) to be tested between the cover web (7) and the corrugated web (10) in a bonding evaluation device (42) of the bonding testing device, which is at least temporarily in signal connection with the detection device (41, 47).

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