Method and device for determining properties of containers made of paper or paperboard

Abstract

A method and apparatus for determining characteristics of containers made of paper or paperboard. The invention relates to a method for determining the properties of a container, in which a container (10) to be inspected is transported along a predetermined transport path and which has a base region (10a), a base body (10b) for receiving a filling material, and a mouth region, and in which the container is at least partially composed of a material comprising paper or cardboard, characterized in that the base body (10b) and the mouth region (10b) are separated from each other. Radiation means (42) irradiate at least a portion of the container with electromagnetic radiation, and sensor means (44) detect radiation reflected and / or transmitted and / or emitted by the container in response to the incident radiation, and from which at least one variable characterizing the container (10) is determined.

Description

Technical Field

[0001] The invention relates to a method and a device for determining properties of a container. Background Art

[0002] Such methods and devices are already known from the prior art. For example, it is known that during the production of plastic containers, properties of plastic containers, such as the wall thickness of the container, etc., are determined. These properties are important for determining the quality of the finished container, for example, whether the determined wall thickness is within a target range.

[0003] In these methods, optical measuring devices are usually used, for example by illuminating the container with light and determining the transmission, from which the container wall thickness can be inferred.

[0004] Recently, there has been increasing effort to create environmentally friendly container alternatives. One approach is to manufacture containers from pulp, especially paper or paperboard pulp. Initial attempts have shown positive results. However, a disadvantage of such containers is that they cannot usually be inspected with visible light, as they are opaque.

[0005] Known in the prior art are beverage containers in the form of concrete paper containers, paper pulp containers, cast fiber containers, etc., which are usually produced from an aqueous mixture in several process steps. After sufficient drying, containers of this type can be filled and closed. However, it is also known that paper pulp shrinks when drying. Thus, a check, for example, for dimensional accuracy can only be performed after sufficient drying.

[0006] Another problem with such containers is that they often still have residual moisture. It is possible in the prior art to determine the residual moisture in the board quality inspection, for example via a moisture meter. In this case, the measurement is carried out in a contact manner with a sword-shaped probe. The sword-shaped probe must be in contact with the material until a sufficiently stable measurement value is obtained.

[0007] However, these methods are not suitable for inspecting containers, which is relevant in this context. In particular, contact measurements can have a significant impact on the performance of the corresponding machines.

[0008] As already mentioned, after the production of such pulp containers and therefore usually before further processing (filling, sealing, etc.), residual moisture is still contained in the container wall. This residual moisture should not exceed a defined value so that the container can be properly handled (especially with regard to stability, wear resistance, mildew resistance, etc.) in the production and processing equipment system, under storage conditions, etc. As already mentioned, there are various established methods or concepts for determining the residual moisture, such as weighing, radiation absorption measurement, etc. However, these methods are either slow and complex or costly or cannot accurately distinguish between differences in wall thickness and different residual moisture contents. Summary of the invention

[0009] The object of the invention is therefore to provide a determination method and a determination device which can be used in particular for containers made of paper pulp as described herein. These objects are achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments and improvements are the subject matter of the dependent claims.

[0010] In the method according to the invention for determining container properties, a container to be checked is transported along a predetermined transport path and has a bottom region, a base body for accommodating a filling material, and a mouth region. Furthermore, the container is made at least in sections or layers and preferably substantially and particularly preferably completely of a material including paper or cardboard and / or consists of such a material.

[0011] According to the invention, the radiation device irradiates at least a portion of the container with electromagnetic radiation and / or impinges electromagnetic radiation on at least a portion of the container.

[0012] Furthermore, the sensor device detects radiation reflected and / or transmitted and / or emitted by the container in response to incident radiation and determines at least one variable characterizing the container from this radiation.

[0013] In the method steps according to the invention described herein, the container itself or the wall or a part of the wall is respectively checked in order to derive therefrom values ​​characterizing them, such as residual moisture or wall thickness. Preferably, the material of the container has a predetermined liquid content and in particular a predetermined water content.

[0014] "Responding to incident radiation" may be understood to mean receiving and / or analyzing and / or examining radiation transmitted by the container. However, it is also possible to receive and / or analyze and / or examine radiation reflected by the container. It is also possible to produce effects on the container due to the incident radiation, in particular (local) temperature increases, and to measure these temperature increases in order to draw conclusions about properties of the container. Another possible response is the emission of fluorescence or phosphorescence.

[0015] In particular, the container is also distinguished by the water content and / or residual humidity from containers known in the prior art, which are in particular made of glass or plastic. The inventors have therefore developed a solution that is particularly suitable for use with water-containing materials and / or for use with paper and / or cardboard materials.

[0016] In a preferred embodiment, the container consists of paper and / or cardboard, and preferably of pulp containing paper or cardboard.

[0017] Preferably, the cross-section of the container mouth is smaller than the cross-section of the container body.

[0018] In another preferred method, the incident radiation is selected from the group of electromagnetic radiation, which includes ultraviolet radiation, radiation in the visible wavelength range, near infrared radiation, far infrared radiation, general infrared radiation, thermal radiation, terahertz radiation, microwave radiation, radio waves, X-rays, radioactive radiation, etc.

[0019] For the method steps described above in the context of the present invention, several possibilities are conceivable. For example, a thermal residual humidity measurement is possible. In this case, a heat input, in particular a defined heat input, can be introduced into the container. This can be done, for example, via thermal radiation when passing through a radiation furnace. Preferably, a temperature measurement is performed before and after the heat input after a predetermined time and in particular a precisely defined time. High humidity means a high heat capacity and leads to a relatively low temperature rise.

[0020] Low humidity leads to a greater temperature rise, since the specific heat capacity of the pulp (i.e. the container material) is much lower. In this way, conclusions can be drawn about the residual humidity from the height of the temperature jump. As explained in more detail below, monitoring and closed-loop control of the drying process is also possible here.

[0021] Preferably, therefore, in a preferred embodiment, the heat input takes place via a first radiation device.

[0022] Preferably, the detection device determines the (local) temperature of the container and / or of a wall of the container.

[0023] Particularly preferably, the heat input and the temperature determination are carried out at this staggered time. Particularly preferably, the temperature determination is carried out within a predetermined time period after the temperature input. Particularly preferably, this time period is less than 20 seconds, preferably less than 10 seconds, preferably less than 5 seconds, preferably less than 3 seconds, preferably less than 2 seconds and preferably less than 1 second.

[0024] In another preferred method, at least two and preferably several temperature measurements are performed. Preferably, these temperature measurements are performed at predetermined points in time and / or predetermined time periods.

[0025] If several temperature measurements are carried out within a precisely defined time grid, conclusions can be drawn not only about the residual humidity but also about the wall thickness from the support point values ​​of the decay curve obtained in this way.

[0026] This is because the cooling of the outer surface is carried out by heat radiation to the outside and heat conduction to the inner wall (in short-time measurements, the proportion of convection is very small and can be ignored). As the wall thickness increases, the proportion of heat conduction increases, so the outside temperature drops faster, that is, the decay time constant is shorter.

[0027] Particularly preferably, the temperature determination of the container also takes place before the heat input. That is, for example, the height of the temperature jump can be determined before passing through the furnace.

[0028] Particularly preferably, the temperature input and the temperature determination are performed during the movement of the container by means of a detection device. Preferably, the temperature determination is performed in a contactless manner, for example by means of a thermopile sensor or a thermal imaging camera, preferably in a wavelength range between 7 μm and 14 μm.

[0029] In a further preferred method, the radiation is infrared radiation in a wavelength range between 800 nm and 2500 nm, preferably between 900 nm and 2200 nm, preferably between 1000 nm and 2000 nm and particularly preferably between 1200 nm and 1800 nm, or the radiation is thermal radiation which causes a defined heat input in at least a portion of the container.

[0030] Particularly preferably, the method is a transmitted light method, in which radiation passes through the container and is received by the detection device. In this method, the front wall and the rear wall of the container are preferably illuminated simultaneously with infrared light. As mentioned above, the wavelength of the SWIR (short wave infrared light) light lies in a suitable spectral range between 1200 nm and 1800 nm. Correspondingly, this spectral range is selected such that water absorbs this wavelength relatively strongly and this wavelength can penetrate the pulp and / or material of the container sufficiently strongly.

[0031] In a further preferred method, the measurement is carried out in at least two spectral ranges and in particular in two spectral ranges with different absorption levels. This makes it easier to compensate for environmental influences.

[0032] In another preferred method, at least one variable characterizing the container is determined in sections in the longitudinal direction of the container and / or the at least one variable characterizing the container is determined according to the longitudinal direction of the container.

[0033] In this way, a measurement or precise mapping of sections of the container is performed according to the longitudinal direction of the container.

[0034] In another preferred method, the measurement of the characterizing variable is carried out during the movement of the container. It is pointed out that this preferred variant is possible for all methods presented here.

[0035] In a further preferred method, the variable characterizing the container is a moisture value and in particular a residual moisture of the container and / or a wall thickness of at least one wall section of the container.

[0036] In another preferred method, the container is rotated during the measurement, and in particular relative to its longitudinal direction. This makes it possible to accurately map the entire side of the container. It should be noted that this preferred embodiment is suitable for the above-described measurement by means of electromagnetic radiation.

[0037] In another preferred method, the sensor device is designed to record spatially resolved images of radiation reflected and / or transmitted and / or emitted by the container. In other words, the sensor device preferably records spatially resolved images of radiation reflected and / or transmitted and / or emitted by the container.

[0038] In a preferred embodiment, the image recording device is a spatial resolution camera (which can be designed both as a matrix camera and as a line scan camera). Particularly preferably, the image recording device or camera can detect areas with excessively high residual moisture as dark areas.

[0039] Furthermore, it is possible to use an integrated surface sensor which measures the residual moisture level of the entire container as a function of the absorption.

[0040] Preferably, the measurement with infrared light is carried out using, in particular, a spatially resolving NIR or SWIR camera. In this case, both a matrix camera and a line scan camera are possible. The image recording device and / or the camera can detect areas with excessively high residual moisture as dark areas.

[0041] Alternatively, in this case, an array consisting of individual sensors can also be used as the sensor device. It is also possible to use an integrated area sensor which measures or determines the residual humidity level of the entire container based on absorption.

[0042] In a further preferred method, the container is at least temporarily located or arranged in the radiation device or between the radiation device and the sensor device for the purpose of determining the property of the container.

[0043] It is possible that the transport path extends between the radiation device and the sensor device. In this case, the container is moved, for example, between the radiation device and the sensor device. In this case, the light path between the radiation device and the sensor device preferably passes through the container and / or is transverse to the transport path of the container. The light path can be perpendicular to the transport path or at an angle thereto.

[0044] In particular, however, the optical path intersects the transport path of the container. In the other case, the container is preferably transported from the radiation device to the sensor device and is therefore temporarily located between the radiation device and the sensor device along the transport path. Preferably, the container is at least temporarily located between a plane passing through the radiation device vertically and perpendicular to the transport path of the container and a plane passing through the sensor device vertically and perpendicular to the transport path of the container.

[0045] In the first case mentioned above, the measurement is performed at the exact time or time period when the container is between the radiation device and the sensor device, while in the second case, the measurement is not performed during the time period when the container is between the radiation device and the sensor device.

[0046] In a further preferred method, light is incident on the container and measurement is carried out by means of the sensor device substantially simultaneously. “Substantially simultaneously” is also understood to mean that the propagation time of the light or radiation is not taken into account, so that the incident light and the reception by the sensor device are substantially offset from each other only by the time required for the radiation to travel from the radiation device to the sensor device.

[0047] In the second embodiment mentioned, as described above, the irradiation and the measurement are intentionally carried out at a time offset. In this case, the sensor device determines in particular the temperature and / or the temperature difference of the heating area and / or the heating container.

[0048] Particularly preferably, the wall thickness of the container is determined from a known or constant residual humidity. In this case, it should be taken into account that the wall thickness is also taken into account when calculating the residual humidity. If the residual humidity is known or constant, the wall thickness can also be determined by measurement.

[0049] When a rotation of the container is preferably performed, for example by rolling, it is possible to measure the entire side surface.

[0050] The above-mentioned thermal measurement has the advantage that thermal emitters and long-wave infrared and / or area sensors are relatively cheap, thereby enabling the realization of a measurement system at a manageable price.

[0051] The measurement of the wall temperature can be performed with several individual such sensors. When several sensors are arranged, for example as a vertical sensor array, the vertical residual humidity distribution can be determined.

[0052] By taking several measurements from different sides, for example several measurements in a 90° grid, and / or by repeated measurements (for example consecutive measurements over a short period of time), a side can be (at least approximately) completely detected. In this way, even uneven distributions of residual moisture can be detected by the measuring technique.

[0053] Alternatively, for measurement purposes one or several thermal infrared cameras may be used.

[0054] In the case of short irradiation times, preferably when the irradiation time is in the range between 10 ms and 1000 ms, preferably between 50 ms and 500 ms and particularly preferably between 70 ms and 400 ms and particularly preferably between 70 ms and 200 ms, and preferably in the case of a short time difference between irradiation and measurement, the wall thickness is practically not included in the measurement result and the moisture content of the wall surface can be determined quite accurately.

[0055] Therefore, it is particularly preferred to carry out the measurement with an irradiation time within the above-mentioned range.

[0056] Preferably, radiation is used which lies in a wavelength range which is strongly or very strongly absorbed by water. Particularly preferably, radiation is used which lies in a wavelength range of 1 μm to 4 μm, preferably 1.2 μm to 3 μm, and particularly preferably radiation with wavelengths of 1.5 μm and 2.5 μm.

[0057] In a further preferred method, the determination and / or measurement of the mentioned properties is carried out in a contactless manner. The advantage of the mentioned methods is that they do not limit throughput. Preferably, in some of the mentioned methods, the measurement can be carried out, in particular with the aid of electromagnetic radiation in two spectral ranges with different absorption intensities, and in this way, for example, material thickness fluctuations, measurement fluctuations and environmental influences can be compensated.

[0058] All of the methods mentioned allow for a quality check of the produced containers. These measured values ​​can also be used to perform subsequent drying of the containers. In this way, closed-loop regulation of material dosage, material mix ratio, water content, drying energy, drying time, etc. can also be performed.

[0059] Preferably, the measurements described herein are performed on unfilled containers. Preferably, the measurements described herein are performed on unsealed containers.

[0060] The measurements described here are preferably carried out on a container which is to be filled for the first time.

[0061] The invention also relates to a device for determining properties of a container, comprising a transport device which transports a container (and preferably a plurality of containers) to be inspected along a predetermined transport path, wherein the container has a bottom region, a base body for accommodating a filling material and a mouth region, and wherein the container consists at least partially and preferably completely of a material comprising paper or cardboard.

[0062] According to the invention, the device comprises a radiation device, which radiates electromagnetic radiation onto at least a portion of the container, and a sensor device, which detects radiation reflected and / or transmitted and / or emitted by the container in response to the incident radiation. Furthermore, an evaluation device is provided, which determines at least one variable characterizing the container from the radiation.

[0063] Therefore, it is also proposed in terms of the device that the measurement of the container is carried out in a contactless manner. Preferably, the measurement is also carried out in-line, ie during the manufacturing operation.

[0064] As mentioned above, electromagnetic radiation and / or capacitance measurement are used in particular for measuring the corresponding variables.

[0065] Preferably, the variable characterizing the container is the moisture and / or the moisture content and / or the wall thickness, in particular the wall thickness in the region of the bottom or the base body of the container.

[0066] Particularly preferably, the transport device is a transport belt or a transport chain.Particularly preferably, the container is transported in a straight direction and in an upright position.

[0067] However, it is also possible for the transport device to have a rotatable carrier on which a plurality of holding elements for holding the containers are arranged.

[0068] In this preferred embodiment, the sensor device has an image recording device, which is designed and arranged to record a spatially resolved image of at least a portion of the container. Particularly preferably, the image recording device is selected from the group of image recording devices, which includes X-ray cameras (especially X-ray line scan cameras or matrix cameras), spatial resolution cameras (especially spatial resolution near infrared cameras), spatial resolution SWIR cameras, spatial resolution LWIR cameras, thermal infrared cameras, arrays and single sensors, etc.

[0069] This embodiment is particularly applicable to all those variants in which measurements are carried out by means of electromagnetic radiation.

[0070] In a further preferred embodiment, the device has a rotating device which is suitable and designed to rotate the container, in particular relative to its longitudinal direction.

[0071] In one variant, it is possible for this rotation to take place while the measurement is being carried out, but it is also possible to rotate and measure in sections several times along the transport path.

[0072] Preferably, the rotating device can have, for example, lateral guide strips which can engage the base body of the container and thus also bring about a rotation of the container.

[0073] The invention also relates to an arrangement for treating containers, which arrangement has a device of the type described above and a drying device for drying the containers, wherein the drying device is preferably controllable as a function of a variable characterizing the container, in particular the residual humidity.

[0074] Preferably, the drying device is arranged downstream of the device described above. Particularly preferably, the control device allows regulation, in particular in the form of a closed loop or closed control circuit (in this case, the sensor device is preferably arranged downstream of the treatment device).

[0075] Thus, for example, the heating power of the drying device can be varied. In addition or in addition, the heating duration can also be varied (for example via the transport speed). Furthermore, the intensity of the convection and / or its local distribution (to avoid local moisture accumulation) can also be varied. The humidity level of the drying air can also be varied.

[0076] Furthermore, the arrangement can have several of the above-described devices. It is therefore possible, for example, to carry out different measurements successively along the transport path, for example a measurement with near-infrared light and a capacitive measurement.

[0077] The measurement results can be used repeatedly, for example, and it is also possible to determine the residual moisture with a first measurement and the wall thickness with a further measurement. A person skilled in the art will recognize that all the devices proposed here can be combined with one another, for example, measurement with X-rays combined with measurement with infrared light, or capacitive measurement combined with thermal measurement, or other embodiments can be combined with one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Further advantages and embodiments can be seen from the accompanying drawings:

[0079] in:

[0080] Figure 1 A schematic diagram of a device according to the present invention is shown;

[0081] Figure 2 shows a schematic diagram of measurement using near-infrared light;

[0082] Figure 3 shows measurements with increasing temperature; and

[0083] Figure 4 A schematic diagram of a device according to the invention is shown. DETAILED DESCRIPTION

[0084] Figure 11 shows a schematic diagram of a device 1 according to the invention. In it, a transport device 2 is provided, for example a conveyor belt, which transports containers 10 along a transport path P. Reference numeral 42 denotes a radiation device, which irradiates radiation onto the container 10, and reference numeral 44 denotes a sensor device, which receives radiation transmitted or reflected by the container. Alternatively, it is also possible to arrange the sensor device 44 shown on the right, which, for example, detects the temperature increase caused by the radiation device 42.

[0085] Reference numeral 14 denotes a drying device, which is used to dry the container 10. Preferably, a control device is provided for controlling the drying device, which controls the drying process in particular as a function of measured values ​​determined by the sensor device, such as in particular the determined residual humidity of the container.

[0086] As mentioned above, the container is a container made of paper or paperboard, in particular a container made of pulp consisting of paper or paperboard.

[0087] Figure 2 A similar measuring arrangement is shown, but here the measurement is carried out using near-infrared light. Here, the transport direction of the containers is perpendicular to the plane of the drawing. Even with this type of measurement, areas with higher residual humidity can be identified, since the infrared radiation is absorbed more strongly in these areas.

[0088] Particularly preferably, the measurement is carried out here with two spectral ranges or more spectral ranges, in particular in order to be able to compensate for environmental influences.

[0089] Figure 3 A measurement is shown which is determined by means of thermal residual humidity. In this case, the container is locally heated and the temperature increase is detected with the sensor device 44. The heating of the container takes place at a first time t1 and the measurement is preferably carried out at a second, slightly later time t2. Preferably, the temperature of the container is also determined before the container is heated. However, it is also possible to determine an ambient temperature which corresponds approximately to the temperature of the container before the heating.

[0090] Figure 4 A measurement is shown which is determined by means of thermal residual humidity. In this case, the container is locally heated and the temperature increase is detected with the sensor device 44. The heating of the container takes place at a first time t1 and the measurement is preferably carried out at a second, slightly later time t2. Preferably, the temperature of the container is also determined before the container is heated. However, it is also possible to determine an ambient temperature which corresponds approximately to the temperature of the container before the heating.

[0091] The applicant reserves the right to claim all features disclosed in the application documents that are essential to the invention, insofar as they are novel compared to the prior art, either individually or in combination. It is further noted that features that can be advantageous in themselves are also described in individual drawings. A person skilled in the art will immediately recognize that a certain feature described in a drawing can be advantageous even without the use of other features in the drawing. In addition, a person skilled in the art will recognize that advantages can also be derived by combining several features shown in a single drawing or in different drawings.

Claims

1. A method for determining properties of a container, wherein a container (10) to be checked is transported along a predetermined transport path, and the container (10) has a bottom region (10a), a base body (10b) for accommodating a filling material, and a mouth region (10c), and wherein the container at least partially consists of a material comprising paper or cardboard, It is characterized in that The radiation device (42) irradiates at least a portion of the container with electromagnetic radiation, and the sensor device (44) detects radiation reflected and / or transmitted and / or emitted by the container in response to the incident radiation and determines at least one variable characterizing the container (10) from the radiation.

2. The method according to claim 1, It is characterized in that The incident radiation is selected from the group of electromagnetic radiation, which includes ultraviolet radiation, radiation in the visible wavelength range, infrared radiation; thermal radiation, terahertz radiation, radio waves, microwave radiation, X-rays and radioactive radiation.

3. The method according to claim 1, It is characterized in that The radiation is infrared radiation in the wavelength range between 1200 nm and 1800 nm, or the radiation is thermal radiation that causes a defined heat input in at least a portion of the container, or the radiation is X-rays in the energy range between 10 keV and 30 keV.

4. The method according to claim 1, It is characterized in that The container consists of a pulp comprising paper or paperboard.

5. The method according to claim 1, It is characterized in that The sensor device records spatially resolved images of the radiation reflected and / or transmitted and / or emitted by the container.

6. The method according to claim 1, It is characterized in that The measurement of the characterizing variable is performed during a movement of the container.

7. The method according to claim 1, It is characterized in that The variable characterizing the container (10) is a moisture value and / or a wall thickness of at least one wall portion of the container (10).

8. The method according to claim 1, It is characterized in that For the purpose of determining a property of the container, the container is at least temporarily arranged between a radiation device (42) and the sensor device (44).

9. The method according to claim 1, It is characterized in that The at least one variable characterizing the container (10) is determined in sections in the longitudinal direction (L) of the container and / or the at least one variable characterizing the container (10) is determined according to the longitudinal direction of the container.

10. The method according to claim 1, It is characterized in that The container is rotated during the measurement.

11. A device for determining properties of a container, the device comprising a transport device (2) for transporting a container (10) to be checked along a predetermined transport path, wherein the container (10) has a base region (10a), a base body (10b) for accommodating a filling material and a mouth region (10c), and wherein the container at least partially consists of a material comprising paper and / or cardboard, It is characterized in that The device (1) comprises a radiation device (42) for incident electromagnetic radiation on at least a portion of the container, and a sensor device (44) for detecting radiation reflected and / or transmitted and / or emitted by the container and / or the portion in response to the incident radiation, and further comprises an evaluation device for determining at least one variable characterizing the container (10) from the radiation.

12. The device (1) according to claim 11, It is characterized in that The sensor device has an image recording device which is designed and arranged to record a spatially resolved image of at least a portion of the container.

13. The device according to claim 11, It is characterized in that The transport device (2), the radiation device (42) and the sensor device (44) are arranged in such a way that the container is at least temporarily located between the radiation device (42) and the sensor device (44).

14. The device (1) according to claim 11, It is characterized in that The device (1) has a rotating device which is suitable and designed to rotate the container relative to its longitudinal direction.

15. An assembly for processing containers, comprising a device (1) according to at least one of the preceding claims and a drying device for drying the containers, wherein the drying device can be controlled as a function of the variable characterizing the containers.

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