Method and device for monitoring the contact pressure of two corrugating rollers for producing corrugated cardboard

Abstract

The invention relates to a method for monitoring the contact pressure of two corrugating rollers (100, 102) for producing corrugated cardboard, having the steps of: – determining, by means of a sensor, a vibration frequency spectrum of at least one of two corrugating rollers pressed against one another with an adjustable contact pressure, the corrugating rollers being configured to produce a corrugated cardboard laminated on at least one side, – determining at least one measured value for characterizing the vibration frequency spectrum, – determining a need for an adjustment of the contact pressure using a logic for predicting the at least one measured value on the basis of the contact pressure, and – outputting the need for an adjustment of the contact pressure. The proposed solution additionally also comprises a device for monitoring the contact pressure of two corrugating rollers for producing corrugated cardboard, a machine for producing corrugated cardboard laminated on at least one side, and a computer program product.

Description

[0001] Method and apparatus for monitoring the contact pressure of two corrugated rollers for the production of corrugated board

[0002] Description

[0003] The proposed solution relates to a method and a device for monitoring the contact pressure of two corrugated rollers for the production of corrugated board.

[0004] Corrugating rollers of this type are particularly well-known from machines for producing corrugated cardboard laminated on at least one side. These rollers are typically convex. A convex shape means that the corrugating rollers deviate from a perfect cylinder, with the diameter varying along a longitudinal axis and being largest in the center. To achieve this convexity and thus a uniform line load, the rollers are pressed against each other with a contact pressure during operation.

[0005] In this regard, US patent 2015 / 0059982 A1 disclosed a single-sided corrugated board machine with a gap adjustment mechanism for setting a gap between a press or glue roller and a corrugating roller.

[0006] Excessive pressure can reduce the service life of the corrugated rollers and mask problems in plant operation. Insufficient pressure can result in incomplete bonding, leading to scrap production.

[0007] However, how the contact pressure can be adjusted is largely a matter of experience and is done by examining the corrugated cardboard being produced.

[0008] Therefore, there is a need to improve the monitoring of the contact pressure.

[0009] This problem is solved by a method according to claim 1 and a device according to claim 15. Accordingly, the proposed method for monitoring a contact pressure of two corrugating rollers for the production of corrugated board comprises at least: - a sensor-based determination of a vibration frequency spectrum of at least one of two corrugating rollers pressed against each other with an adjustable contact pressure, which are configured for the production of corrugated board laminated on at least one side,

[0010] - Determining at least one numerical measure to characterize the vibration frequency spectrum,

[0011] - determining a contact pressure adjustment requirement with a logic for predicting at least one numerical value depending on the contact pressure, and

[0012] - an output of the contact pressure adjustment requirement.

[0013] In operation, the two corrugated rollers pressed against each other form a vibrating system. The vibrations vary depending on the contact pressure. The entire vibration behavior can be comprehensively described by a vibration frequency spectrum. By characterizing the vibration frequency spectrum with at least one numerical value, the contact pressure of the corrugated rollers can be numerically evaluated and thus adjusted directly using a single numerical value. This eliminates the need for an experience-based and therefore subjective assessment by an inspector as to whether, in which direction, and by how much the contact pressure should be adjusted (contact pressure adjustment requirement). Instead, the proposed method enables the contact pressure adjustment requirement to be determined reliably and objectively using computer support during operation.This can reduce rejects due to insufficient contact pressure and / or excessive wear of the corrugating rollers due to excessive contact pressure. This can reduce manufacturing costs.

[0014] Furthermore, the proposed solution can prevent problems in plant operation from being masked by excessively high contact pressures, thus preventing the plant from being operated under potentially harmful conditions.

[0015] According to a further supplementary or alternative embodiment of the proposed method, determining the required contact pressure adjustment can involve varying the contact pressure. During this variation, the corrugated rollers can be operated sequentially at at least two different contact pressures. For each of these different contact pressures, at least one metric value can be determined and used to calculate the required contact pressure adjustment. This can enable a particularly resource-efficient determination of the required contact pressure adjustment. As an example, according to the proposed method, a contact pressure can first be varied. Based on the metric values ​​determined for the different contact pressures, a prediction of the required contact pressure adjustment can be made, and the corresponding adjustment requirement can be output.

[0016] In an exemplary embodiment of the proposed method, determining the at least one metric value for a single variation involves determining the at least one metric value for three different contact pressures. A variation in which three different contact pressures are applied can generate a statistically evaluable data set for the at least one metric value. This can improve the determination of the required contact pressure adjustment.

[0017] According to a further supplementary or alternative embodiment of the proposed method, during variation, at least one metric value can be determined at a given initial contact pressure, at a contact pressure increased by a predetermined value Ap, and at a contact pressure reduced by the predetermined value Ap. Thus, at least one metric value can be determined at pressures p1, p2, and p3, where p1 = p2 - Ap, and p3 = p2 + Ap. This can, in particular, enable automatic variation of the contact pressure, thereby achieving faster and more reliable variations.

[0018] The predetermined value Ap can be an unchanging and / or predefinable value according to the proposed procedure. For example, the predetermined value can be specified by a plant operator and / or determined based on historical variations.

[0019] For example, if several variations around a predetermined value have not resulted in any variation in the measured values, the predetermined value can be increased.

[0020] According to the proposed method, it is therefore conceivable and possible that the variation is self-learning in order to determine by which predetermined value the contact pressure should be varied.

[0021] In a further refinement of the proposed method, the logic can include the application of a trend function that at least approximately describes the development of the measured value as a function of the contact pressure. The trend function can thus approximate a functional relationship between the at least one measured value and the contact pressure. An actual functional relationship therefore does not need to be known.

[0022] In particular, the logic can include using the tendency function to predict the position of an optimum of the measure as a function of the contact pressure. The prediction of the position can be limited to predicting whether the optimum is found at a higher or lower contact pressure.

[0023] It is conceivable and possible, in principle, that the trend function describes the development of the measured value only for a limited range of contact pressures. For example, an arbitrarily complex functional relationship between the at least one measured value and the contact pressure can be described locally by a first-order polynomial (a straight line). Likewise, a functional relationship can be described by a higher-order polynomial. In this case, the range in which the functional relationship can be approximately described by a polynomial of a specific order may depend on the order of the polynomial.

[0024] The functional relationship can also be described, for example, by a linear combination of polynomials of different orders (Taylor series). It may be true that the computational effort required to determine the trend function increases with increasing degree of the Taylor series. However, the range in which the trend function approximately describes the functional relationship between at least one measurement value and the contact pressure may also increase with higher order.

[0025] The tendency function indicates whether a vibration of the at least one corrugated roller can be reduced by increasing or decreasing the contact pressure. This direction of the required contact pressure adjustment can be determined, in particular, from the sign of the gradient of the tendency function. Thus, the tendency function can be used to determine whether the contact pressure can be optimized by increasing or decreasing it.

[0026] In principle, at least one parameter can have smaller values ​​with decreasing vibration amplitude and larger values ​​with increasing vibration amplitude. Therefore, at least a local optimum of the contact pressure can be characterized by at least a local minimum of the at least one parameter.

[0027] By repeatedly determining the required contact pressure adjustment, outputting the required contact pressure adjustment, and adjusting the contact pressure accordingly, a convergence to an optimal contact pressure is possible.

[0028] According to one embodiment of the proposed method, the trend function can be determined from a plurality of measured values ​​obtained at different contact pressures. As explained above, it is conceivable and possible to determine a trend function from the measured values ​​using a Taylor series.

[0029] In one embodiment of the proposed method, the trend function can be a regression line between at least three values ​​of the at least one metric measured at different contact pressures. Using such a trend function can conserve computing resources and reduce the time required to determine the contact pressure adjustment.

[0030] Based on the tendency function, it is also possible to determine by what amount the contact pressure should be adjusted to reduce, and in particular minimize, the vibration of the corrugated rollers. This amount can be proportional to the magnitude of the gradient.

[0031] Furthermore, determining the required contact pressure adjustment is conceivable and possible even without variation. The required contact pressure adjustment can be implemented using a feed-forward control system.

[0032] A control system generally refers to a technical process in which a specific process is continuously monitored and adjusted to achieve and maintain a desired target value. A control system therefore differs from a control system in that, within a control system, the process is not necessarily monitored and adjusted.

[0033] A feed-forward control system is a technical process that uses information about input disturbances or signals to proactively implement corrective measures to achieve the desired output. This process aims to minimize the impact of disturbances before they affect the system by applying predictive correction. In this case, the need for adjustment can be detected before the contact pressure deviates from a permissible range.

[0034] The trend function can be suitable for taking into account the influence of time-varying parameters, such as wear, temperature, or product specifications. This allows for a prediction of how the contact pressure should be adjusted in the future to ensure optimal contact pressure despite these changes.

[0035] According to another exemplary embodiment, the logic can be implemented not with a determined, but with a previously known trend function. Such a known trend function can be calculated as a fit of a series of historical measurement-contact pressure data pairs or using simulations.

[0036] The trend function can be stored as an example. After determining the measure for an initial contact pressure, it can be ascertained whether the contact pressure is already within a predetermined range around the optimum of the known trend function. If at least one measure is found to be outside the predetermined range, the required contact pressure adjustment can be determined by adjusting the contact pressure to the optimum known according to the known function. This eliminates the need to vary the contact pressure when determining the required adjustment. This can reduce the time required to determine the required adjustment and avoid potential scrap resulting from variations.

[0037] According to a further supplementary or alternative embodiment of the proposed method, the logic can be trained using an artificial intelligence (AI) that is trained with measured and / or simulated values ​​of at least one metric at a multitude of different contact pressures. The trained AI can thus be configured to determine, based on a value of at least one metric at an initial contact pressure, whether the vibration can be optimized by changing the contact pressure. If the AI ​​recognizes that the contact pressure can be optimized, it can also specify a magnitude and direction for adjusting the contact pressure to the optimum. By using the AI, both the need for variation to determine the trend function and the use of a rigid, pre-known trend function can be eliminated.The device's ability to determine the required contact pressure adjustment can be continuously readjusted. This allows the logic to adapt if the functional relationship between the measured value and the contact pressure changes due to wear and / or altered environmental conditions. This can make the monitoring of the contact pressure more reliable in the long term.

[0038] For example, artificial intelligence can be trained using a neural network. This can enable a particularly effective and rapid determination of the required contact pressure adjustment.

[0039] With a further refinement of the proposed method, the algorithm can be trained and / or executed on a remote computer. This can shift the computing power required for executing the proposed method from the location of the corrugating rollers to the remote computer. This can enable more efficient resource management.

[0040] According to a further supplementary or alternative embodiment of the proposed method, at least one metric for the respective contact pressure can be determined after and / or during each adjustment of the contact pressure and added to the training data along with the respective contact pressure. This can enable continuous retraining of the computer. In particular, the computer can thus adapt to a changing functional relationship of at least one metric related to the contact pressure.

[0041] It is conceivable and possible that the AI ​​is retrained at regular time intervals and / or in response to a training command and / or in response to the addition of a training dataset. It is also conceivable that the AI ​​is retrained as soon as a change in the training data exceeds a certain threshold, for example, one percent of the training data.

[0042] According to a further supplementary or alternative embodiment of the proposed method, the vibration of at least one corrugated roller can be measured over a period of time to determine the vibration-frequency spectrum. This can enable a particularly simple measurement of the vibration as a displacement over time. According to a further supplementary or alternative embodiment of the proposed method, the vibration measured over time can be transformed into the frequency domain. This allows the vibration-frequency spectrum to be determined quickly and without significant computational effort, based on a displacement-time relationship that is easy to record.

[0043] The transformation can be implemented using a Fourier transform as an example.

[0044] According to a further supplementary or alternative embodiment of the proposed method, a vibration sensor can be provided on each of the corrugated rollers for determining the vibration frequency spectrum.

[0045] According to a further supplementary or alternative embodiment of the proposed method, at least one measure can encompass the maximum of the vibration frequency spectrum. Accordingly, the measure can be the vibration frequency at which the vibration frequency spectrum exhibits the greatest amplitude.

[0046] Alternatively or additionally, at least one measure can include one or more of the following values:

[0047] - a root mean square,

[0048] - a crest factor,

[0049] - one standard deviation,

[0050] - a kurtosis, and

[0051] - a skew.

[0052] For example, the aforementioned metrics can be defined in a discrete frequency space as follows:

[0053] peak = max(|a|)

[0054] When determining at least one measure based on the vibration frequency spectrum, vibrations at a tooth engagement frequency of the rotating corrugating rollers can always be disregarded, regardless of the choice of measure. Therefore, after determining the vibration frequency spectrum, the amplitude of the vibration at the tooth engagement frequency, or a predetermined range around the tooth engagement frequency, can be removed from the spectrum. This can improve the statistical analysis. The same applies to any harmonic overtones of the tooth engagement frequency.

[0055] It is also conceivable and possible to use only a portion of the vibration frequency spectrum when determining at least one metric. For example, only a predetermined portion of the frequencies above the tooth engagement frequency can be used. Similarly, it is conceivable to use only a predetermined portion of the frequencies above a harmonic overtone of the tooth engagement frequency.

[0056] According to a further supplementary or alternative embodiment of the proposed method, the contact pressure can be automatically adjusted depending on the required contact pressure adjustment via an adjustment device equipped with an electronically controlled motor or actuator (externally powered adjustment). This can, in particular, enable the control of the contact pressure. Thus, in response to the determination of the required contact pressure adjustment, the contact pressure can be automatically set accordingly. This can reduce operating costs and avoid downtime due to potential operator errors.

[0057] According to one embodiment of the proposed method, the required adjustment of the contact pressure can be determined by identifying a deviation of at least one specific metric value from a target value. In other words, using at least one specific metric value and an associated target value, a check can be performed to determine whether the contact pressure needs to be adjusted, i.e., whether a contact pressure adjustment is required. This can enable a particularly fast, reliable, and automated check of the required adjustment within the framework of contact pressure control.

[0058] For example, the target value can be a predetermined value. This can further simplify the implementation of the demand assessment.

[0059] Alternatively, the target value can be learned during the operation of a device set up for the proposed procedure, or adjusted from an initial value. Accordingly, an optimum for at least one parameter can be identified during operation of the device and continuously or regularly stored as the target value. This allows for consideration of an optimum parameter that changes due to aging, maintenance, or environmental conditions—i.e., the parameter at optimal contact pressure. For example, this can prevent a situation where replacing individual components in the device leads to a change in the optimum, resulting in an incorrect demand assessment.

[0060] According to a further embodiment of the proposed method, a target value for the contact pressure can be determined based on the deviation of at least one specific parameter using the logic for predicting that parameter. This can enable targeted control of the contact pressure in response to a detected need for adjustment.

[0061] The target value can be either a relative value (i.e., a pressure difference from a current value) or an absolute value. With a relative target value, knowledge of the actual absolute contact pressure may be irrelevant. This can simplify implementation.

[0062] For example, the logic can predict a target contact pressure suitable for shifting at least one measured value from its current value towards the target value. This can enable continuous optimization of the contact pressure when a corresponding contact pressure cannot be directly derived from the target value of the measured value, or when such derivation involves considerable computational effort. Thus, even with complex relationships between the measured value and the contact pressure, automated monitoring or control of the contact pressure can be implemented in a resource-efficient manner.

[0063] As a further example, the logic can predict a target contact pressure that matches the setpoint of the measured value. In other words, the determined measured value for the predicted target contact pressure can correspond to the setpoint of the measured value within a prediction error. This can enable rapid correction in case of excessively high or low contact pressures. In particular, a control loop can be implemented that quickly and precisely corrects any impermissible contact pressure.

[0064] According to a further embodiment of the proposed method, the target contact pressure can be determined in response to the deviation of at least one specific measurement exceeding a predetermined value. In other words, a needs assessment can first be performed to check whether the at least one specific measurement deviates from a target value by a predetermined amount. If the assessment is negative, the process can be terminated, or it can be repeated to implement continuous monitoring. If the assessment is positive, a target contact pressure can be determined using the logic for predicting the at least one measurement. This target contact pressure can be output to an electronically controlled contact device, which is configured to adjust the contact pressure according to the target contact pressure via an external force, i.e., an actuator.

[0065] According to a further supplementary or alternative embodiment of the proposed method, the required contact pressure adjustment can be indicated acoustically and / or visually, in particular via a display. This can enable an operator to adjust the contact pressure.

[0066] The specified contact pressure adjustment requirement can include instructions for adjusting the contact pressure. These instructions can specify the direction and amount by which the contact pressure should be adjusted. The proposed solution naturally also includes a computer-implemented version of the proposed procedure.

[0067] The aforementioned problem is also solved by the proposed device for monitoring the contact pressure of two corrugating rollers for the production of corrugated board. The device therefore comprises at least the following:

[0068] - two corrugated rollers pressed against each other with adjustable contact pressure,

[0069] - at least one sensor for measuring the vibration of at least one of the corrugated rollers during normal operation,

[0070] - at least one output device for outputting a contact pressure adjustment requirement, and

[0071] - a control unit connected to the output device and the at least one sensor, which is configured to determine a vibration frequency spectrum of the at least one corrugated roller based on the measured vibration, to determine at least one measure for characterizing the vibration frequency spectrum, and to determine a contact pressure adjustment requirement with logic for predicting the at least one measure as a function of the contact pressure, as well as to output the contact pressure adjustment requirement via the output device.

[0072] The proposed device is designed to numerically evaluate the contact pressure of the corrugating rollers by characterizing the vibration frequency spectrum with at least one metric and to output a specific numerical value for adjusting the contact pressure. This eliminates the need for an experience-based and therefore subjective assessment by an inspector as to whether, in which direction, and by how much the contact pressure should be adjusted (contact pressure adjustment requirement). Instead, the proposed device enables the contact pressure adjustment requirement to be determined reliably and objectively during operation using computer support. This can reduce scrap due to insufficient contact pressure and / or excessive wear of the corrugating rollers due to excessive contact pressure. It also eliminates scrap that typically occurs when adjusting the contact pressure. This can reduce manufacturing costs.

[0073] According to a further supplementary or alternative embodiment of the proposed device, the device can include a remote computer configured to determine the required contact pressure adjustment. For example, the control unit can be configured to determine at least one numerical value for a contact pressure and send the numerical-contact pressure data pair to the remote computer. The remote computer can receive the data pair and be configured to determine a required contact pressure adjustment. The computer can send the determined required contact pressure adjustment to the control unit. The control unit can be configured to receive the required contact pressure adjustment and send it to the output device.

[0074] It is also conceivable and possible that the control unit sends the vibration measured at at least one contact pressure and / or the vibration frequency spectrum determined from the vibration for that at least one contact pressure to the remote computer. This can further reduce the required computing power at the location of the control unit.

[0075] It is also conceivable and possible that the remote computer is equipped with memory on which the parameters for determining the required contact pressure adjustment and / or a pre-defined tendency function are stored. The remote computer and / or the control unit can be configured to receive and send data to each other via either a wireless or a wired connection.

[0076] Furthermore, the remote computer can be configured to receive data from multiple control units. For example, it is conceivable and possible that the remote computer receives measurement-contact pressure data pairs from different control units, each of which has acquired this data from different pairs of corrugated rollers.

[0077] The remote computer can use the data pairs from the various control units to train a computer. This can improve the size of the data set and thus the quality of the specific contact pressure adjustment requirement.

[0078] The AI, trained with a large amount of data from a large number of control units, can determine the required contact pressure adjustment for each individual control unit. With a further refinement of the proposed method, at least one numerical value for the respective contact pressure can be determined after and / or during each adjustment and added to the training data along with the respective contact pressure. The training data can be stored on non-volatile memory that is linked to the remote computer or control unit. As soon as a predetermined criterion for retraining is met, the remote computer or control unit can train the AI.

[0079] In the case of training the AI ​​on the remote computer, the optimized weighting factors can be stored in non-volatile memory. If the control unit is configured to execute the AI ​​to determine the required contact pressure adjustment, the control unit can request a transfer of the optimized weighting factors. The optimized weighting factors are then sent to the control unit in response to this request.

[0080] It is conceivable and possible that the control unit regularly or upon a command requests the optimized weighting factors from the control unit.

[0081] According to a further supplementary or alternative embodiment of the proposed device, the vibration of the at least one corrugated roller can be determined via at least one sensor arranged on the corrugated roller. In principle, any device capable of determining a displacement over time and / or a displacement for one or more specific frequencies is suitable as a sensor.

[0082] Examples of suitable sensors include accelerometers or devices for directly measuring the deflection, such as an interferometer.

[0083] It is also conceivable and possible to have multiple sensors per corrugated roller.

[0084] According to a further configuration of the proposed device, the device for outputting the contact pressure adjustment requirement can be equipped with a screen to display the contact pressure adjustment requirement to an operating person.

[0085] Furthermore, the proposed device can be equipped with an electronically controlled pressure device configured to apply pressure to one of the corrugated rollers. The pressure device can be coupled to the control unit and configured to automatically adjust the pressure according to the specified pressure adjustment requirement. This allows for fully automatic monitoring and adjustment of the pressure. Thus, the control unit can be configured to regulate the pressure. According to a conceivable and possible embodiment of the proposed device, the at least one control unit can be configured to determine the deviation of at least one specific dimension from a target value in order to determine the required pressure adjustment.In other words, using at least one specific measurement value and an associated setpoint, a needs assessment can be performed to determine whether the contact pressure needs adjusting, i.e., whether a contact pressure adjustment is required. This can enable a particularly fast, reliable, and automated needs assessment, especially within the context of control systems.

[0086] According to a further embodiment of the proposed device, the at least one control unit can be configured to determine a target value of the contact pressure based on the deviation of at least one specific measurement value, using logic for predicting that measurement value. This can enable targeted control of the contact pressure in response to a detected need for adjustment.

[0087] According to a further embodiment of the proposed device, the at least one control unit can be configured to determine the target value of the contact pressure in response to the deviation of at least one specific numerical value exceeding a predetermined value.

[0088] For example, the proposed device can be part of a single-facer or a double-facer.

[0089] According to a further supplementary or alternative embodiment of the proposed method, the device for carrying out the proposed method may be set up.

[0090] Furthermore, the aforementioned task is also solved by a computer program product that includes machine-readable instructions which cause a control unit of the proposed device to carry out the proposed procedure during execution.

[0091] The proposed explanations regarding the advantages and possible implementations of the proposed method apply analogously to the proposed device and the proposed computer program product. The accompanying figures illustrate possible implementation variants of the proposed solution.

[0092] This shows:

[0093] Figure 1 shows a schematic representation of a first embodiment of the proposed device for corrugated board production with monitoring of a contact pressure,

[0094] Figures 2A and 2B are schematic representations of two further embodiments of the proposed device, which are set up for automatic adjustment of the contact pressure.

[0095] Figure 3 shows a schematic representation of a variant embodiment of the proposed device with a remote computer.

[0096] Figure 4 shows a schematic vibration frequency spectrum of the

[0097] Corrugated rollers,

[0098] Figure 5 shows a vibration frequency spectrum based on measurement data of the

[0099] Corrugated rollers,

[0100] Figure 6 shows a schematic representation of a trend function that includes at least one numerical value for different contact pressures, and

[0101] Figures 7 to 10 show flowcharts of different embodiments of the proposed method.

[0102] Figure 1 shows a schematic representation of the proposed device for monitoring the contact pressure of two corrugating rollers 100, 102 for the production of corrugated board. The device comprises a first corrugating roller 100, which is pressed against a second corrugating roller 102 with a contact pressure. The two corrugating rollers 100, 102 are configured to produce corrugated board. A sensor 300 is arranged on the first corrugating roller 100 for measuring a vibration of the first corrugating roller 100 during the intended operation of the corrugating rollers 100, 102. The sensor 300 is coupled to a control unit 400, which is configured to receive the data measured by the at least one sensor 300 and to determine a vibration frequency spectrum based on the measured data.Furthermore, the control unit 400 is configured to determine at least one measure for characterizing the vibration frequency spectrum and, based on this measure, to use logic to predict the measure as a function of the contact pressure. The required contact pressure adjustment describes whether, in which direction, and by what value the contact pressure should be adjusted to reduce vibration of the first corrugated roller 100.

[0103] Furthermore, an output device 500 is coupled to the control unit 400. The control unit 400 is configured to send the specified contact pressure adjustment requirement to the output device 500. The output device 500 is configured to output the contact pressure adjustment requirement. In the embodiment shown in Figure 1, the contact pressure is introduced into the corrugated rollers 100 and 102 via a pressure device 200 arranged above the first corrugated roller 100. The pressure device 200 is designed with a belt module. The pressure device 200 therefore comprises a deflecting roller 204 and a tensioning roller 202. A circulating pressure band 206 runs over the tensioning roller 202 and the deflecting roller 204. An adjustable distance from the tensioning roller 202 to the deflecting roller 204 defines the contact pressure that the pressure band 206, which rests against the first corrugated roller 100, transmits into the corrugated roller 100.

[0104] In further embodiments that differ from the embodiment shown in Figure 1, any other form of a pressure device 200, 201 is conceivable which is suitable for introducing a pressure into one of the corrugated rollers 100, 102.

[0105] In principle, the device can also have a different number of sensors 300 for measuring the vibration than the one sensor 300 shown here. The at least one sensor 300 can be arranged on each of the corrugated rollers 100, 102. In the case of multiple sensors 300, these can be distributed across both corrugated rollers 100, 102 or arranged on one corrugated roller 100, 102.

[0106] Figure 2A shows an embodiment with an electronically controllable contact pressure which, according to the variant shown in Figure 1, is introduced into the corrugated rollers 100, 102 via a pressure band 206. For this purpose, the output device 502 is designed with an electronically adjustable adjustment device 502. In the embodiment shown in Figure 2A, the adjustment device 502 is an adjustable bearing of the tension roller 202. Accordingly, in response to a determination of a contact pressure adjustment requirement, an adjustment signal can be sent to the electronically adjustable bearing in order to adjust the contact pressure by adjusting the tension roller 202 according to the contact pressure adjustment requirement. The output of the contact pressure adjustment requirement thus includes the adjustment of the contact pressure. The embodiment shown in Figure 2A is therefore designed for automatic, computer-aided monitoring and control of the contact pressure.

[0107] Figure 2B shows another possible embodiment of the proposed device, which is designed for automatic control of the contact pressure. Here, the contact pressure is introduced into the corrugated rollers 100, 102 via a pressure device 201, which includes a pressure roller. In this case as well, the output device 504 is equipped with an electronically controlled adjustment device. This adjustment device also incorporates an electronically adjustable bearing. In this instance, the electronically adjustable bearing controls the pressure with which the pressure roller is pressed against the first corrugated roller 100. Thus, in response to a determination of a required contact pressure adjustment, the contact pressure is automatically and externally adjusted by moving the pressure roller.

[0108] In principle, it is conceivable and possible that the proposed device includes a remote computer that performs individual parts of the proposed procedure.

[0109] Figure 3 shows a possible embodiment with a remote computer 402 coupled to the control unit 400. The coupling encompasses any type of connection that enables data exchange between the control unit 400 and the remote computer 402. In the embodiment shown in Figure 3, the control unit 400 is configured to determine the vibration frequency spectrum via the sensor 300 and send it to the remote computer 402. The remote computer 402 is configured to receive the vibration frequency spectrum for one or more contact pressures and, using artificial intelligence and / or a pre-known trend function and / or a trend function determined from the measured values, to calculate a required contact pressure adjustment. The required contact pressure adjustment is sent back to the control unit 400. The control unit 400 then sends the required contact pressure adjustment to the output unit 502.

[0110] Figure 4 shows a schematic vibration frequency spectrum 600 as a function of the vibration amplitude a versus the frequency f. Vibration amplitudes a for various frequency ranges are included. At a tooth engagement frequency 602 of the corrugating rollers 100, 102, as well as at multiples of the tooth engagement frequency 603 (harmonic overtone), the vibration frequency spectrum 600 exhibits amplitudes a of large magnitude. Above both the tooth engagement frequency 602 and the harmonic overtone 603, broad frequency ranges with lower vibration amplitudes 604, 605, 606, 607 (secondary bands) are found. The secondary bands 604, 605, 606, 607 can be divided into upper 604, 605 and lower 606, 607 secondary bands. The lower secondary bands 606 and 607 can be found below the tooth engagement frequency 602 and the harmonic overtone 603.Accordingly, the upper secondary bands 604 and 605 are found above the tooth engagement frequency 602 and the harmonic overtone 603. To determine at least one numerical value, the proposed device can be configured to use only a portion of the vibration frequency spectrum 600, for example, the upper secondary bands 604 and 605, or exactly one of the upper secondary bands 604 and 605.

[0111] Figure 5 shows a vibration frequency spectrum 600 based on a measurement, corresponding to the frequency distribution shown schematically in Figure 4.

[0112] Based on the vibration frequency spectrum 600, at least one metric value is calculated. If the contact pressure of the corrugated rollers 100, 102 is varied, the vibration behavior of the corrugated rollers 100, 102 changes. In particular, the secondary bands also change within the vibration frequency spectrum 600. For example, the amplitudes a and the width of the secondary bands 604, 605, 606, 607 can increase as the corrugated rollers 100, 102 vibrate more intensely. This change leads to a change in at least one metric value.

[0113] Figure 6 shows three values ​​Q1, Q2, Q3, marked with an "x", for the at least one measure Q at three different contact pressures p1, p2, p3 in a measure-contact pressure diagram. For higher contact pressures p, the determined values ​​of measure Q1, Q2, Q3 shown in Figure 6 exhibit a decreasing trend. A decreasing value of measure Q is associated with a reduced vibration of the corrugated rollers 100, 102. To determine the required contact pressure adjustment, a regression line Q_p1 is determined for the three determined values ​​Q1, Q2, Q3 of the at least one measure Q. Within the range of the measured values, the regression line Q_p1 approximates the behavior of a functional relationship Q_p2 between measure Q and contact pressure, which may be unknown in practice. The regression line Q_p1 is therefore a trend function in the sense of the proposed solution.From the slope, or gradient, of the regression line Q_p1, it can be seen that an optimum Q4;p4 of at least one measure Q related to the contact pressure p can be found at pressures higher than p3.

[0114] The contact pressure adjustment requirement derived from the trend function Q_p1 thus includes at least the specification that the contact pressure p must be increased compared to p3. For example, the contact pressure adjustment requirement can also include a specification of a contact pressure p by which the initial contact pressure must be increased. This amount can depend, in particular linearly, on the slope of the trend function Q_p1. By repeatedly determining the trend function Q_p1 according to a previously determined contact pressure adjustment requirement, the device thus converges towards the optimal contact pressure p4.

[0115] Figures 7, 8 and 9 show exemplary sequences of the proposed procedure.

[0116] The embodiment of the proposed method shown in Figure 7 comprises determining the vibration frequency spectrum 600, determining at least one measure Q for characterizing the vibration frequency spectrum 600, and determining a contact pressure with logic for predicting at least one measure Q as a function of the contact pressure p. Subsequently, the required contact pressure adjustment is output.

[0117] In further alternative embodiments of the proposed method, determining the at least one measure Q can involve varying the contact pressure p. Based on this variation of the contact pressure, it is possible to determine a trend function Q_p1, which approximates a potentially unknown functional relationship Q_p2 between the measure Q and the contact pressure p.

[0118] Figure 8 shows a possible embodiment of the method, in which the contact pressure p is varied and a trend function Q_p1 is determined. Specifically, the contact pressure p is adjusted such that at least one metric Q is determined for three different contact pressures p1, p2, p3. Determining the trend function Q_p1 involves calculating a regression line. From this regression line, it is derived how the contact pressure p must be varied to reduce the metric Q, or the vibration of the corrugated rollers 100, 102. In principle, the trend function Q_p1 can comprise not only a regression line but also any polynomial.

[0119] In alternative or supplementary configurations, it is also conceivable and possible that the logic for predicting the at least one measure Q, depending on the contact pressure p, is trained with an artificial intelligence that is trained with measured and / or simulated values ​​of the at least one measure Q of a large number of different contact pressures p.

[0120] Furthermore, it is conceivable and possible that the output of the required contact pressure adjustment includes an externally actuated adjustment of the contact pressure p. Thus, the entire proposed procedure can be executed using a computer.

[0121] Figure 9 shows a possible embodiment of the method as a computer-aided procedure. After starting the procedure for monitoring the contact pressure p, a vibration frequency spectrum 600 of at least one of the corrugated rollers 100, 102 is first determined by sensors. Based on the vibration frequency spectrum 600, a numerical value Q is determined. Following the previous explanations for determining the required contact pressure adjustment, a check is then performed to see if a contact pressure adjustment is required. If no contact pressure adjustment is detected, the vibration frequency spectrum 600 is determined again. This enables continuous monitoring of the contact pressure p.However, if a need for pressure adjustment is detected, the pressure p can be adjusted according to the specific pressure adjustment requirement by means of the output device 502, 504 which is equipped with an electronically controllable adjustment device in a computer-aided and fully automatic manner.

[0122] Figure 10 shows a further embodiment of the proposed method as an automated control procedure. In contrast to the embodiment shown in Figure 9, here, after determining the at least one parameter Q, a deviation of the at least one specific parameter Q from a target value is determined. Subsequently, it is checked whether the deviation exceeds a predetermined value. If the check is negative, the procedure is repeated, i.e., another vibration frequency spectrum 600 is determined. If the check is positive, a target value of the contact pressure p is determined using the logic for predicting the at least one parameter Q. This target value of the contact pressure p is output to an electronically controlled contact device 502, 504 in order to adjust the contact pressure p according to the target value of the contact pressure p by external force, i.e., via an actuator. Subsequently, the procedure is also repeated.Thus, this design variant enables permanent monitoring and control of the contact pressure p.

[0123] The proposed solution is not limited to the specific embodiments discussed 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.

[0124] Reference symbol list

[0125] 100, 102 Grooved roller

[0126] 200, 201 pressure device

[0127] 202 Tension roller

[0128] 204 Deflection roller

[0129] 206 Pressure band

[0130] 300 Sensor

[0131] 400 control unit

[0132] 402 Remote Computer

[0133] 500, 502, 504 Output device

[0134] 600 vibration frequency spectrum

[0135] 602 Tooth engagement frequency

[0136] 603 first harmonic of the tooth engagement frequency

[0137] 604 upper accessory band of tooth engagement frequency

[0138] 605 upper secondary band of the first harmonic

[0139] 606 lower accessory band of tooth engagement frequency

[0140] 607 lower secondary band of the first harmonic f frequency a amplitude p, p1, p2, p3, p4 pressure

[0141] Q, Q1, Q2, Q3, Q4 metric

[0142] Q_pi, trend function

[0143] Q_p2 functional relationship

Claims

Claims 1. Method for monitoring the contact pressure of two corrugating rollers (100, 102) for the production of corrugated board, comprising: - sensory determination of a vibration frequency spectrum (600) of at least one of two corrugated rollers (100, 102) pressed against each other with an adjustable contact pressure (p, p1 , p2, p3, p4) which are set up for the production of a corrugated board laminated on at least one side, - Determine at least one measure (Q, Q1 , Q2, Q3, Q4) to characterize the vibration frequency spectrum (600), - Determining a contact pressure adjustment requirement with a logic for predicting at least one numerical value (Q, Q1 , Q2, Q3, Q4) as a function of the contact pressure (p, p1 , p2, p3, p4), and - Output of the contact pressure adjustment requirement.

2. Method according to claim 1, characterized in that determining the contact pressure adjustment requirement comprises a variation of the contact pressure (p, p1 , p2, p3, p4).

3. Method according to claim 2, characterized in that during the variation, the at least one numerical value (Q, Q1 , Q2, Q3, Q4) is determined at an initial value of the contact pressure (p2), a contact pressure increased by a predetermined value (p3) and a contact pressure reduced by the predetermined value (p1).

4. Method according to one of claims 1 to 3, characterized in that the logic comprises the application of a tendency function (Q_p1) which approximately describes a development of the measure (Q, Q1, Q2, Q3, Q4) as a function of the contact pressure (p, p1 , p2, p3, p4).

5. Method according to claim 4, characterized in that the trend function (Q_p1) is a regression line between at least three values ​​of the at least one measure (Q, Q1, Q2, Q3, Q4) measured at different contact pressures (p, p1 , p2, p3, p4).

6. Method according to one of the preceding claims, characterized in that the logic is configured with a logic that is equipped with measured and / or simulated Values ​​of at least one measure (Q, Q1, Q2, Q3, Q4) are trained at a variety of different contact pressures (p, p1 , p2, p3, p4).

7. Method according to claim 6, characterized in that after and / or during each adjustment of the contact pressure (p, p1 , p2, p3, p4) the at least one numerical value (Q, Q1, Q2, Q3, Q4) for the respective contact pressure (p, p1 , p2, p3, p4) is determined and added to the training data together with the respective contact pressure (p, p1 , p2, p3, p4).

8. Method according to one of the preceding claims, characterized in that, to determine the vibration frequency spectrum (600), a vibration of the at least one corrugated roller (100, 102) is measured during the period.

9. Method according to claim 8, characterized in that the oscillation measured in the period is transformed into the frequency domain.

10. Method according to one of the preceding claims, characterized in that the at least one numerical value (Q, Q1, Q2, Q3, Q4) corresponds to the maximum of the vibration frequency spectrum (600).

11. Method according to one of the preceding claims, characterized in that the contact pressure (p, p1 , p2, p3, p4) is automatically adjusted by external force depending on the contact pressure adjustment requirement.

12. Method according to one of the preceding claims, characterized in that a deviation of at least one specific numerical value (Q, Q1, Q2, Q3, Q4) from a target value is determined for determining the contact pressure adjustment requirement.

13. Method according to claim 12, characterized in that, based on the deviation of the at least one specific numerical value (Q, Q1, Q2, Q3, Q4) a target value of the contact pressure (p, p1 , p2, p3, p4) is determined using the logic for predicting the at least one numerical value (Q, Q1 , Q2, Q3, Q4).

14. Method according to claim 13, characterized in that the target value of the contact pressure (p, p1 , p2, p3, p4) is determined in response to the fact that the deviation of at least one specific numerical value (Q, Q1 , Q2, Q3, Q4) exceeds predetermined value.

15. Device for monitoring the contact pressure of two corrugated rollers (100, 102) for the production of corrugated board, comprising: - two corrugated rollers (100, 102) pressed against each other with an adjustable contact pressure (p, p1 , p2, p3, p4), which are designed to produce at least one-sided laminated corrugated board, - at least one sensor (300) for measuring a vibration of at least one of the corrugated rollers (100, 102) during intended operation, - at least one output device (500, 502, 504) for outputting a contact pressure adjustment requirement, and - a control unit (400) connected to the output device (500, 502, 504) and the at least one sensor (300), which is configured to determine a vibration frequency spectrum (600) of the at least one corrugated roller (100, 102) based on the measured vibration, to determine at least one measure (Q, Q1, Q2, Q3, Q4) for characterizing the vibration frequency spectrum (600), and to determine a contact pressure adjustment requirement with a logic for predicting the at least one measure (Q, Q1, Q2, Q3, Q4) as a function of the contact pressure (p, p1, p2, p3, p4), and to output the contact pressure adjustment requirement via the output device (500, 502, 504).

16. Device according to claim 15 characterized in that the output device (500, 502, 504) is set up for graphical output of the contact pressure adjustment requirement and / or for externally actuated adjustment of the contact pressure (p, p1, p2, p3, p4).

17. Device according to claim 15 or 16, characterized in that the at least one control unit (400) is configured to determine a deviation of the at least one specified dimension value (Q, Q1, Q2, Q3, Q4) from a setpoint value for determining the contact pressure adjustment requirement.

18. Device according to claim 17, characterized in that the at least one control unit (400) is configured to determine a target value of the contact pressure (p, p1, p2, p3, p4) based on the deviation of the at least one specific measure (Q, Q1, Q2, Q3, Q4) with the logic for predicting the at least one measure (Q, Q1, Q2, Q3, Q4).

19. Device according to claim 18, characterized in that the at least one control unit is configured to determine the target value of the contact pressure (p, p1 , p2, p3, p4) in response to the fact that the deviation of the at least one specified numerical value (Q, Q1, Q2, Q3, Q4) exceeds a predetermined value.

20. Machine for producing corrugated board laminated on at least one side, comprising a device according to any one of claims 15 to 19.

21. Computer program product comprising machine-readable commands which a Control unit (400) of a device according to one of claims 15 to 19 cause, during execution, a method according to one of claims 1 to 14 to be carried out.

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