Procedure and testing system for testing containers

Abstract

The invention relates to a method for testing containers to be filled and identifying unstable containers in a filling plant, comprising the following test steps: - Illuminating a container to be inspected with polarized test light, capturing the test light reflected or transmitted by the container to be inspected using a change-based test camera which has an image sensor configured to generate output signals exclusively in response to detected changes in brightness, wherein the test camera is associated with a polarizer which is oriented such that the polarization direction of the light passing through the polarizer differs from the polarization direction of the test light generated by the illumination device, - Checking the output signals generated by the inspection camera for the presence of local brightness changes, determining a measure of the structural integrity of the container under inspection, at least on the basis of a detected local brightness change and predefined test criteria, and - Characterizing the container under test with regard to its stability, at least on the basis of the determined measure of structural integrity, using a test algorithm and generating a container stability signal based thereon, whereby the container under test is subjected to stress during the test. The stress is generated by a contact force that presses the container against a filling valve of a filling device in the filling plant.

Description

[0001] The present invention relates to a method for testing containers to be filled and identifying unstable containers in a filling plant.

[0002] When filling free-flowing products, such as liquids or powders, into glass or plastic containers, especially bottles intended for transport and / or retail use, fully automated filling systems are typically employed. In addition to the actual filling device, which introduces the product into the containers, these systems include other components. Particularly when the containers being filled are reusable, a cleaning system is usually installed upstream of the filling device to remove contaminants.

[0003] To monitor the cleaning process, particularly to check for non-removable soiling or bulky foreign objects inside the container, and to detect damaged containers, such as those with cracks or chips in the opening or on the container body, a suitable inspection device is provided. Such an inspection device is also known as an EBI (Empty Bottle Inspector).

[0004] A conveying device is provided for transporting the containers within the filling plant, which conveys the containers to be filled in one conveying direction at least from the inspection device to the filling device.

[0005] During the filling process, containers are often pressurized. This occurs, for example, when filling bottles with carbonated beverages. To prevent foaming and / or degassing of the contents, the pressure in the container can be increased before filling, a process also known as pre-pressurization. Containers are also frequently purged with a purge gas, such as carbon dioxide, before filling and may also be pre-pressurized to create an oxygen-deficient or oxygen-free atmosphere to protect the contents. Furthermore, temperature fluctuations can occur throughout the filling process, which also place structural stress on the containers.

[0006] One danger is that, particularly when containers are pressurized during pre-pressurization and / or the actual filling process, individual containers can burst. Such container or bottle bursts can undesirably reduce the productivity of the filling process and even result in serious machine damage and thus lengthy downtime of the filling line. Since a filling device in a bottling plant usually has several filling valves to increase throughput, a burst container also poses the risk that material fragments produced during the bursting process could contaminate adjacent filling valves or the outer walls of neighboring containers. This represents a significant danger to the end consumer.

[0007] Filling lines typically have a damage detection system that can identify a container rupture. When such an event is detected, the affected filling valve, as well as adjacent filling valves, are flushed or purged to remove any adhering container fragments and product residue. Containers located near the ruptured container at the time of the event are diverted and discarded for safety reasons. This can involve up to 20 or more containers.

[0008] In addition to the detection of defective containers, especially visibly damaged or unclean containers, by the aforementioned inspection device, there is therefore a need to also detect unstable containers.

[0009] Unstable containers are defined as those that, due to structural defects or wear, lack sufficient pressure and / or temperature resistance and are therefore prone to bursting (i.e., potentially exhibiting an increased risk of bursting). In other words, unstable containers have a higher probability of bursting, for example, under pressure during the filling process.

[0010] To avoid the damage events described above, a way should be created to identify such unstable (and therefore burst-prone) containers in good time and to remove them from the filling process before a damage event occurs, or to modify the filling process in such a way that the probability of a damage event occurring is reduced.

[0011] From DE 10 2019 129 726 A1 a test system for testing transparent containers to be filled is known, in which a test for unstable containers is carried out on the basis of a wall parameter, which represents the wall thickness of the container to be tested as determined by means of a wall thickness sensor, and a container parameter and / or a process parameter.

[0012] A generic method is known from DE 10 2022 103 998 B3. The method described therein for testing containers to be filled and identifying unstable containers in a filling plant comprises the following test steps: - Illuminating a container to be inspected with polarized test light, capturing the test light reflected or transmitted by the container to be inspected using a change-based test camera which has an image sensor configured to generate output signals exclusively in response to detected changes in brightness, wherein the test camera is associated with a polarizer which is oriented such that the polarization direction of the light passing through the polarizer differs from the polarization direction of the test light generated by the illumination device, - Checking the output signals generated by the test camera for the presence of local brightness changes (i.e., checking whether local brightness changes are / were detected by the image sensor), - Determining a measure of the structural integrity of the container under test, at least on the basis of a detected local change in brightness and specified test criteria, and - Characterizing the container under test with regard to its stability, at least on the basis of the determined measure of structural integrity, using a test algorithm and generating a container stability signal based thereon, whereby the container under test is subjected to stress during the test.

[0013] The generic method comprises a combination of two different measures. The first measure consists of illuminating or passing through the container to be tested with polarized test light and analyzing or filtering the reflected or transmitted test light with respect to its polarization direction using a suitably aligned polarizer before it is captured by the test camera. The second measure consists of not capturing this analyzed or filtered test light with a conventional camera, but rather using a change-based test camera.

[0014] The generation of polarized test light can be achieved using an illumination device, which may comprise either a light source that already produces polarized light, such as a laser, or a combination of a light source that produces unpolarized light and an additional polarizer that polarizes the unpolarized light produced by the light source. Such an additional polarizer is not the one associated with the inspection camera. The polarization direction of the light passing through the polarizer associated with the inspection camera is, for example, perpendicular to the polarization direction of the test light produced by the illumination device. The orientation of the polarizer associated with the inspection camera can also generally be chosen such that test light passing through or being reflected from intact areas of the container is at least substantially suppressed by the polarizer associated with the inspection camera.The polarizer associated with the inspection camera thus fulfills the function of an analyzer. It utilizes the effect that structural anomalies of the container can alter the polarization direction of the incident inspection light, so that an image of the container being inspected, projected onto the image sensor of the inspection camera, can exhibit local changes in brightness, which serve as an indicator of these structural anomalies.

[0015] The second measure involves the use of a change-based inspection camera, referred to here as such. This type of camera is also called an event camera and comprises an image sensor consisting of a two-dimensional array of light-sensitive elements or pixels. Unlike a conventional image sensor, the output or image signals are generated solely in response to detected changes in brightness. An example of such an image sensor is also known as a retinomorphic or neuromorphological image sensor. The output signals generated by this type of image sensor can be interpreted as a three-dimensional data array. Due to the array-like design of the image sensor, the spatial coordinates of the sensor can be considered the first and second dimensions, and time the third dimension.While conventional image sensors typically accumulate charge in the light-sensitive elements or pixels over a predetermined acquisition time, which is then read out and digitized, a change-based inspection camera detects changes in brightness. Each image element or pixel is evaluated independently and asynchronously. Brightness changes are thus detected almost in real time, resulting in an increase or decrease in the signal amplitude of the output signal. If the brightness detected by a pixel does not change, the signal amplitude of the output signal generated by that pixel approaches zero. In principle, an image sensor in a change-based camera (e.g., a retinomorphic or neuromorphological sensor) generates as its output signal a pixel-based first-order temporal derivative or differentiation of the brightness profile detected by a given pixel.

[0016] A change-based inspection camera with such an image sensor offers both an increased dynamic range and a significantly higher frame rate compared to an inspection camera with a conventional image sensor. While the dynamic range of a conventional image sensor is typically between 40 and 60 dB, a typical retinomorphic or neuromorphological image sensor has a dynamic range of up to 120 dB. In comparison to conventional image sensors, which can achieve frame rates of up to 120 fps (frames per second), and in the case of high-speed cameras, whose frame rates can reach approximately 10,000 fps, the frame rate of change-based inspection cameras can be on the order of 1,000,000 fps. This allows for the highly precise capture of objects with a wide range of brightness or dynamic range, as well as moving objects.Artifacts such as under- or over-driving of the image sensor or the occurrence of motion blur in moving objects can be avoided by using a change-based inspection camera.

[0017] Although the aforementioned change-based inspection camera can be described as an "event" camera, the term "event" should not be misinterpreted to mean that such a camera can only record events that are considered actual damage events in this context. Rather, it can record any event that leads to detectable changes in brightness on the image sensor. Changes in brightness occurring on the image sensor are therefore considered sensor-relevant "events."

[0018] The subsequent checking of the output signals for the presence of local brightness changes may include temporal and / or spatial filtering of the output signals, in particular smoothing.

[0019] The aforementioned test criteria define, in particular, the prerequisites that must be met for a detected local change in brightness to be considered relevant to integrity. This can include, for example, a decision as to whether a crack or scratch is present. The stated measure of structural integrity can be determined, for example, based on the number and / or severity of structural anomalies identified as a result of changes in brightness.

[0020] In the next step, the container under test is characterized with regard to its stability, using a test algorithm and the previously determined measure of structural integrity as a basis. For example, the test algorithm can define the conditions that must be met for a failure to meet a certain level of structural integrity to be considered relevant to the container's stability. The test algorithm might, for instance, include a decision as to whether a predefined size and / or number of cracks or scratches has been exceeded.

[0021] A lighting device designed to generate polarized test light and the test camera may include beam-shaping optical elements. For example, the lighting device may include one or more condenser lenses for beam expansion. The test camera may have a lens that, by imaging the test light reflected or transmitted by the container under test, creates an image of the container on the image sensor. Due to the use of polarized light, this image contains only a portion of the image information compared to an image captured with unpolarized light.

[0022] During testing, the container under test is subjected to stress. This allows for the detection of structural anomalies that do not occur, or only occur in a weakened form, under standard conditions where the container is subjected to no or only minimal structural stress. The stress can be generated by progressively increasing the internal pressure and / or temperature of the container. This can be achieved, for example, through a dedicated testing procedure in which a purging or pressurizing gas, such as CO2, is introduced into the container and its pressure is continuously increased. The stress can also be generated during a cleaning process in which the container temperature is raised by introducing heated cleaning agent and, if necessary, the pressure is also increased.

[0023] The object of the invention is to provide a method for testing containers to be filled and for identifying unstable containers in a filling plant, in which the generation of the stress acting on the container is improved.

[0024] The problem is solved by a method having the features of claim 1. Advantageous embodiments of the invention are described in the dependent claims, the description and the drawings.

[0025] In the method according to the invention, the stress is generated by a contact force that presses the container against a filling valve of a filling device of the filling system.

[0026] A filling system in which the test method according to the invention is applied can comprise various individual devices, as mentioned above. A typical characteristic device of a filling system is, for example, a filling device designed as a filling carousel, which has a plurality of circularly arranged filling positions for the individual containers and corresponding filling valves. The containers are fed sequentially, picked up at a respective filling position, and connected to a filling valve. In this process, the containers can be mounted on lifting plates in the filling device, which move along a conveyor track, lifting the container and pressing it from below against a respective filling valve arranged on a rotating ring vessel.They remain in this filling position for a specific rotation period and undergo various rinsing, pre-tensioning, and filling processes until they are subsequently removed from the filling carousel and may be subjected to further procedures, such as checking the fill level and / or sealing the container. To remove them, the lifting plates with the filled containers are lowered again, thereby releasing them from the filling valve.

[0027] According to the invention, the inspection camera is arranged close to the position on the filling carousel where the containers to be filled come into contact with the filling valve. However, it is not fundamentally excluded that additional inspection cameras are provided, which may be arranged at other positions within the filling system.

[0028] The advantage of the method according to the invention lies in the fact that the stress acting on the container under test, which is required to detect structural anomalies of the container using the change-based inspection camera, is not generated pneumatically by introducing a purge gas and pre-stressing the container under test, but rather mechanically, e.g., by means of a conveying device. Such a conveying device, associated with the filling device, is generally present in filling systems to feed the containers to be filled to the filling device, press them against the filling valves during the filling process, and release and transport them away after filling. It has been shown that this allows the stress necessary for testing to be generated simply and in a controlled manner.

[0029] To ensure container tracking and, if necessary, appropriate handling of containers identified as unstable, container tracking means may be provided. These container tracking means may, for example, include generating identification signals, preferably by using a shift register, wherein the identification signals enable tracking and / or identification of a container during its dwell time at various positions in the filling plant, and wherein different identification signals can be linked together in such a way that a respective container is traceable and / or identifiable at least from the time of its (first) inspection until the time of its filling.

[0030] According to an advantageous embodiment of the method, the contact force is progressively increased during testing. This can be achieved, for example, by appropriately controlling the aforementioned conveyor device. Often, the height adjustment of the conveyor device's lifting plates is controlled by a cam mechanism. By modifying or fine-tuning the cam mechanism in the area of ​​the testing camera, the force profile can be adjusted as desired.

[0031] Advantageously, if potential container instability is detected, the progressive increase in contact force is stopped immediately or upon reaching a predefined threshold. For this purpose, the lifting plates can be equipped with appropriate actuators. This prevents potentially unstable containers from bursting due to excessive contact pressure, especially in combination with the additional mechanical stress occurring during the filling process.

[0032] According to a further advantageous embodiment, to compensate for a movement of the container to be tested during the detection of the test light, a received light path stretched between the moving container and the image sensor is modified in such a way that the relative position of an image of the container to be tested on the image sensor does not change at least during a predetermined detection period.

[0033] By modifying the received light path, the field of view (FOV) of the inspection camera is adjusted according to the movement of the container under test. This prevents local changes in brightness, which are not due to reduced structural integrity of the container but rather to relative movement between the container and the camera during the acquisition of the reflected or transmitted test light, from distorting the test result. Changes in polarization that occur when stress is applied to the container under test have been shown to exhibit a certain inertia. Containers are typically transported continuously through a filling line.Briefly stopping individual containers is not normally possible and could only be integrated into the filling system with costly technical modifications. Therefore, the present invention offers a cost-effective solution for making the instability testing of containers even more reliable using a change-based inspection camera.

[0034] The modification of the received light path during the acquisition of the test light is achieved in such a way that, in effect, the image of the container under test is fixed on the image sensor. This ensures that light signals originating from a specific location on the container under test accumulate in the same sub-area of ​​the image sensor, at least during the acquisition period, and can be detected accordingly when brightness differences occur. This also prevents brightness differences caused by motion blur from potentially masking brightness differences that are attributable to relevant structural anomalies of the container under test. The method according to the invention thus avoids the generation of both false positive and false negative container stability signals.

[0035] It has been shown that the acquisition period, i.e., the period during which the position of the image on the image sensor should not change, should preferably be between 20 and 100 ms. Particularly in an arrangement where reflected test light is captured, it is necessary to use test light with a relatively high brightness. This high luminance can, under certain circumstances, make the testing procedure particularly sensitive to any movement of the container. Therefore, particularly significant improvements can be expected with a reflection configuration.

[0036] According to a further advantageous embodiment of the method, at least one tracking device is provided which moves the inspection camera and / or a deflecting device arranged in the receiving light path between the container to be inspected and the inspection camera translationally and / or rotationally, at least during the acquisition period, such that the relative position of an image of the container to be inspected on the image sensor does not change, at least during the predetermined acquisition period. The tracking device thus serves to modify the receiving light path according to the invention. The tracking device can be synchronized with the movement of the container to be inspected, for example, by receiving corresponding synchronization signals from a control unit of the filling system.Synchronization can be performed with regard to both the start of a cycle and the movement speeds of the container being tested and the tracking device. If necessary, it may be required to return the inspection camera or the deflection device to its starting position. During this time, no containers are tested. To prevent incorrect evaluation, data transmission to or evaluation within the evaluation unit can be prevented during this return period. It is also possible to combine the two aforementioned alternatives of a moving inspection camera and a moving deflection device.

[0037] According to a further advantageous embodiment, at least one inspection camera is arranged on the tracking device, wherein the tracking device moves the at least one inspection camera continuously or discontinuously along a motion path. The motion path can include translational and / or rotational sections. The tracking device can, for example, be designed as a circulating conveyor belt, a cam-guided transport carriage, or a rotating carrier for the at least one inspection camera.

[0038] Advantageously, the tracking device incorporates multiple inspection cameras, each with image capture areas that do not overlap or only partially overlap. This allows for the simultaneous inspection of several containers, such as those moving along a conveyor belt or in a filling carousel of the bottling plant. Furthermore, even while one inspection camera is returning to its starting position, during which it is temporarily unavailable for inspection, another camera can be activated. This enables continuous inspection of a container flow.

[0039] According to a further advantageous embodiment, the deflection device comprises a mirror, a polygon wheel, or a prism wheel, wherein the tracking device is configured to rotate the deflection device with the same or periodically alternating direction of rotation. When using only a deflection device, it is possible to position the test camera in a fixed location. This simplifies the design effort for routing the necessary electrical cables between the test camera and an evaluation or control unit, which supplies the test camera with power and transmits the acquired data. Examples of deflection devices with the same direction of rotation include, in particular, a polygon wheel or a prism wheel. An example of a deflection device with a periodically alternating direction of rotation is a oscillating mirror. In principle, multiple test cameras can also be used when employing a single deflection device.If necessary, multiple deflection devices can be provided, corresponding to the number of inspection cameras. This also enables largely continuous inspection of a container flow.

[0040] According to a further advantageous embodiment, the tracking device is configured to move the inspection camera and / or the deflection device in at least two spatial directions. This allows the tracking device to track the field of view in two spatial directions, for example, in the direction of the conveying direction of the containers through the filling system or the conveying device, and additionally in the direction of the contact force or in a corresponding direction of movement of the container towards the filling valve.

[0041] According to a further advantageous embodiment, checking the output signals generated by the inspection camera for the presence of local brightness variations includes analyzing the output signals using pattern recognition methods, in particular segmentation, classification, and / or machine learning methods. This advantageous embodiment defines, in particular, an advantageous configuration of the aforementioned inspection criteria. Analyzing the output signals using pattern recognition methods can also serve, in particular, to distinguish brightness variations caused, for example, by otherwise intact edge regions of the container under inspection from brightness variations generated by actual structural anomalies.

[0042] According to a further advantageous embodiment, at least one process parameter is received from a filling device of the filling system, and the characterization of the container under test with regard to its stability is additionally carried out based on this process parameter. The aforementioned at least one process parameter can be, for example, the filling pressure and / or the filling temperature of the material during the actual filling process. The clamping pressure or the pressure of any purging or clamping gas that may be used can also be used as a process parameter. Other possible process parameters include the pressure and / or temperature of a cleaning fluid with which the containers to be filled are cleaned before filling.

[0043] According to a further advantageous embodiment, the filling system receives at least one container parameter, and the characterization of the container under test with regard to its stability is additionally carried out based on this container parameter. The container parameter can, for example, be a universal property of the container type used, such as its size, shape, or target wall thickness—i.e., a container type parameter. Furthermore, an individual property of the respective container under test can also be considered as a container parameter during the container characterization. For this purpose, for example, a measured wall thickness of the container or a wear parameter representing the wear condition of the container can be taken into account. Such an individual container parameter can, for example, be provided by an additional inspection device of the filling system, such as an EBI (Electronic Boiler Inspection Unit).One exemplary wear parameter is the so-called degree of scratching (also known as the degree of scuffing). The degree of scratching describes the condition of the container surface. To determine this, particularly in the case of reusable containers or bottles, somewhat exposed areas of the container's surrounding wall are examined. These areas can regularly come into contact with corresponding wall sections of neighboring containers or other structures during the filling process or transport. The container surface, especially in these exposed wall sections, becomes increasingly scratched with each use, thus increasing the surface roughness, which can be used as a measure of wear. Another container parameter that can be considered is the measured wall thickness, which can be determined using a suitable wall thickness sensor.The measured wall thickness can be compared to a target wall thickness, which can be considered a container type parameter, so that the wall thickness can also be used as a measure of container wear. Another container parameter could be, for example, the centricity of a cylindrical container, i.e., a measure of maintaining a circular cross-section or a measure of the consistency of the ratio between the radius of the inner wall and the radius of the outer wall.

[0044] The container parameters can be determined using suitable sensors, for example, additional image sensors or other sensors such as ultrasonic sensors. The container parameter(s) determined by the aforementioned inspection device or by other means can be transmitted via an associated control unit to an evaluation unit of a testing system described in more detail below, wherein preferably each inspected container can be assigned the container parameters determined for it by means of a container tracking device.

[0045] According to a further advantageous embodiment, a filling device of the filling system optionally receives an event parameter representing a specific damage event occurring during the filling of a container. The predefined test criteria and / or the test algorithm are adapted, at least on the basis of the event parameter received. The filling device can, for example, have a damage detection system configured to record container damage occurring during filling as a damage event and to generate the aforementioned event parameter, at least on the basis of the recorded damage event. In addition to the actual occurrence of a damage event, the event parameter can also contain other parameters, which, for example, can represent further boundary conditions such as the filling pressure prevailing during the occurrence of the damage event.The phrase "if applicable" in the context explained above is intended to clarify that the event parameter is only received if an underlying damaging event has occurred. If no such damaging event occurs, no corresponding event parameter is generated, transmitted, and / or received.

[0046] The configuration described above also includes, in particular, the case where the adaptation of the predefined test criteria and / or the test algorithm is based on a multiple of potentially received event parameters, where the multiple event parameters represent respective damage events. Considering multiple event parameters can, for example, be achieved by determining a damage rate based on a multiple of damage events and a total number of filled containers, and then using this rate as the basis for adapting the test criteria and / or the test algorithm. Determining the damage rate can, in particular, refer to a specific period, so that the damage rate corresponds to the number of damage events per period divided by the total number of filling operations in that period.

[0047] The adaptation of test criteria or the test algorithm based on event parameters that characterize individual damage events can be supported by a container tracking system. This allows for the identification of previously determined parameters for a damaged container, particularly its structural integrity, and the adaptation of the test criteria or the test algorithm based on these parameters—for example, by changing defined limit values. The adaptation of the test criteria or the test algorithm is carried out in such a way as to improve the detection of unstable containers. This improvement includes both a reduction in the damage rate and a reduction in the rate of false-positive container characterizations; that is, the number of containers erroneously characterized as unstable should also be reduced.

[0048] In this context, it has proven advantageous to adapt the test criteria and / or the test algorithm, at least on the basis of a database in which at least one received event parameter is stored for a plurality of damage events, preferably using machine learning methods, in such a way as to improve the detection of unstable containers.

[0049] Such configurations for adapting the test criteria or the test algorithm can be considered a form of data-driven modeling. This modeling or model building can be achieved using various machine learning methods. In particular, reinforcement learning can be employed, whereby the model underlying the test algorithm receives positive feedback if a container survives the filling process without damage and negative feedback if the container bursts during filling. To prevent an increase in the non-filling or rejection rate beyond a desired level, the non-filling or rejection rate also triggers negative feedback.To achieve the desired optimization goal of neither rejecting inherently unstable containers nor filling inherently unstable containers under standard conditions, it can be implemented that the negative feedback from a damage event is weighted more heavily than the non-filling or rejection rate. Alternatively or additionally, the inspection criteria and / or the inspection algorithm can be improved through machine learning using statistical methods, such as predicting a higher-level target variable that is essential for the overall process. Thus, the inspection criteria or the inspection algorithm are not adjusted based on individual events during the filling process ("damage event or no damage event"), but rather based on the damage rate and the non-filling or rejection rate.An evaluation unit designed to carry out the procedure can be trained using historical data from the database to map the parameters assigned to the containers to a target event, "container bursting." Using machine learning methods, the evaluation unit learns to associate combinations of container and process parameters with a probability score for a damage event, and thus to predict damage events for a container in the filling process from the available data. Such learning methods enable continuous optimization even with changing process parameters and different container types.

[0050] Various machine learning methods, such as deep learning, boosted trees, random forests, or support vector machines, can be used in all cases to develop a model underlying the test criteria and / or the test algorithm. A key aspect of the proposed approaches is that the model building (as a result of a learning process based on process data) leads to an individualized model of the filling plant to be tested and the containers used within it. Based on this model, events arising from the specific use of the filling plant at a given time, in combination with the containers used, can then be specifically predicted. This approach goes beyond the use of machine learning technologies to implement local functions (e.g.,(in addition to the use of a deep neural network for image recognition of the output signals generated by the inspection camera or other image sensors in the overall process), since the overall process itself is modeled and all relevant process elements are taken into account for target variable prediction.

[0051] According to a further advantageous embodiment, the container stability signal, in the event of a detected potential container instability, includes instructions for the filling system to fill the container in a modified manner or to divert the container before filling. The container stability signal with these instructions is preferably output to a filling device of the filling system or to a container diverting device located upstream of the filling device. In this case, the container stability signal already contains an instruction that enables the filling device to handle the container to be filled appropriately.Filling a container in a modified manner when potential container instability is detected means, in particular, that the filling device deviates from a predefined standard procedure or standard process parameters when filling potentially unstable containers or containers with relatively low stability compared to containers that do not exhibit container instability. Alternatively or additionally, the container stability signal, when container instability is detected, can include instructions for a container discharge device located upstream of the filling device to discharge the container in question. Such a container discharge device can, for example, be integrated into or downstream of the inspection device, in which case the aforementioned inspection camera or...Another inspection camera is arranged upstream of the container discharge device in the conveying direction.

[0052] According to a further advantageous embodiment, the instructions to the filling device include not filling the container to be filled, or filling it with a reduced quantity and / or a reduced filling pressure, performing a purge with a purge gas or pressurizing gas at a reduced pressure prior to filling, and / or not closing the filled container. A particular advantage of these embodiments is that it is not absolutely necessary to divert containers identified as unstable before filling. This reduces the design complexity. In particular, by only partially filling or not closing a container that is not filled or only partially filled, it is possible to effectively mark it. This allows such a container to be detected and diverted accordingly using a fill level monitoring device located downstream of the filling device.Since most filling lines already have such level-checking devices, no additional equipment is required for sorting out containers identified as unstable. Furthermore, reducing the mechanical stress allows for the gentler filling of containers that only exhibit a certain degree of reduced stability. This can, for example, extend the service life of reusable containers.

[0053] The invention further relates to the use of a testing system in a filling plant for filling products into containers, wherein the testing system for testing containers to be filled and identifying unstable containers in a filling plant comprises at least one container testing device, wherein the container testing device comprises a lighting device configured to illuminate a container to be tested with polarized test light, a change-based testing camera comprising an image sensor configured to generate output signals exclusively in response to detected changes in brightness and for detecting the test light reflected or transmitted by the container to be tested, and a polarizer associated with the testing camera, wherein the polarizer is oriented such thatthat the polarization direction of the light passing through the polarizer differs from the polarization direction of the test light generated by the lighting device, and includes an evaluation unit which is designed to - to check the output signals received from the container testing device for the presence of local brightness changes (i.e., to check whether local brightness changes are / were detected by the image sensor), - to determine a measure of the structural integrity of the container under test, at least on the basis of a detected local change in brightness and predefined test criteria, and - to characterize the container to be tested with regard to its stability, at least on the basis of the determined measure of structural integrity, using a test algorithm, and to generate a container stability signal based on this, wherein the filling system includes at least one filling device on which at least one container testing device of the test system is arranged, wherein the container to be tested is subjected to stress during testing, which is generated by a contact force that presses the container against a filling valve of the filling device.

[0054] The filling device can include a control unit which may be connected to an evaluation unit of the testing system, for example, to receive the container stability signal from the evaluation unit. The filling system may optionally include further components such as an inspection device for inspecting the containers to be filled, which is configured to determine at least one container parameter, and a conveying device which is configured to convey the containers to be filled at least from the inspection device to the filling device. Preferably, the evaluation unit is combined with the control unit of the filling device for bidirectional signal transmission and, optionally,The control unit is coupled to one or more other components of the filling system, at least for receiving signals from this control unit. The received signals include at least identification signals and / or parameters, such as process or container parameters. At least one part of the control unit is preferably configured to generate identification signals, preferably by using a shift register, which enable tracking and / or identification of a container during its time in the assigned component of the filling system. The evaluation unit is further configured to link the identification signals received from each control unit in such a way that a container can be tracked and / or identified at least from the time of its inspection until the time of its filling.The filling plant may preferably also include a container cleaning device located upstream of the inspection device.

[0055] A combined control and evaluation unit can also be used as an evaluation unit, which is set up in conjunction with the other components of the testing system and, if necessary, also with components of the filling system to carry out the method according to the invention and its advantageous embodiments.

[0056] Further advantages of the method according to the invention and advantageous embodiments will become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. It is advantageous for those skilled in the art to also consider these features individually and to combine them into meaningful further combinations. In particular, those skilled in the art will also consider advantageous embodiments of the method as corresponding advantageous embodiments of the testing system, and vice versa.

[0057] They show: Fig. 1 a schematic block diagram of a filling plant with which a method according to an embodiment of the invention can be carried out, in top view; and Fig. 2 A schematic side view of the filling device of the bottling plant of Fig. 1.

[0058] In the following, the same reference symbols are used for identical or similar components.

[0059] Fig. Figure 1 schematically shows a filling system 20, which is configured to convey preferably transparent containers or bottles 16, to be filled by the filling system 20, along a conveying path 18 in a conveying direction indicated by an arrow. Various components are provided along the conveying path 18, which are simplified here as blocks. In addition to the components shown, other components may also be provided.

[0060] The containers or bottles 16 conveyed in the conveying direction first enter a container cleaning device 22, where they are cleaned. The cleaned bottles 16 are then conveyed to an inspection device 24, where an inspection is carried out to detect defective bottles 16, i.e., those that are obviously damaged, worn, and / or insufficiently cleaned. The bottles 16 are subsequently conveyed to a filling device 28, which, if necessary, pre-pressurizes the bottles 16 to be filled using a purging gas or a pressurizing gas and fills them with the product to be filled, for example, a liquid, in particular a beverage. In the exemplary embodiment, the filling device 28 is designed as a so-called filling carousel, which has a plurality of filling positions into which the individual bottles or containers 16 are continuously received and placed again after completion of the filling process.

[0061] Various process steps can take place within the filling device 28. At the beginning of the filling process, i.e., after a bottle 16 to be filled has been connected fluid-tight to a filling adapter or filling valve, a purge gas, for example CO2, can first be introduced into the bottle 16 to create a protective atmosphere for the product. Subsequently, the pressure inside the container 16 to be filled can be continuously increased until the desired target pressure is reached. The product is then filled into the container 16. Pre-pressurizing the container 16 serves, in particular, to prevent the CO2 contained in carbonated products from escaping and thus avoids foaming.

[0062] The filling device 28 may be provided with an integrated or separate damage detection system, which is designed to detect damage events such as bursting or rupturing bottles 16.

[0063] The container cleaning device 22, the inspection device 24 and the filling device 28 each have a control unit, wherein in Fig. 1 Only the control unit 30 of the filling device 28 is shown as a separate component. The container cleaning device 22 and the inspection device 24, or their control units, as well as the control unit 30 of the filling device 28, are connected to an evaluation unit 40, which is part of a test system according to the invention. The control units can be, for example, programmable logic controllers (PLCs).

[0064] The testing system further comprises a container testing device 42 arranged in the area of ​​the filling device 28, which in the exemplary embodiment is arranged near the container inlet. The container testing device 42 comprises a lighting device 44 with a light source (not shown separately) and an associated polarizer 46 for generating polarized test light. The bottles 16 to be tested are illuminated by the polarized test light generated by the lighting device 44. The test light passing through the bottles 16 is detected by a change-based testing camera 50. The testing camera 50 has an image sensor that is configured to generate output signals exclusively in response to detected changes in brightness.An example of such an image sensor is also called a retinomorphic or neuromorphological image sensor and, similar to conventional image sensors, has a large number of light-sensitive elements or pixels arranged in rows and columns.

[0065] The test camera 50 is associated with a further polarizer 48, which is oriented such that only those components of the test light whose polarization direction matches that of the polarizer 48 can enter the test camera 50. The polarization direction of the polarizer 48 associated with the test camera 50 is rotated relative to the polarization direction of the test light or the polarization direction of the polarizer 46 associated with the lighting device 44. The angle between the two polarization directions of the polarizers 46 and 48 can, for example, be 90° or a value lower than zero.

[0066] Those components of the test light that pass through intact areas of the container 16 or bypass the container 16 laterally generally experience no or only a slight change in their polarization direction and are therefore suppressed by the polarizer 48 and do not reach the test camera 50. Those components of the test light that pass through areas of the container 16 exhibiting structural anomalies or material stresses experience some change in their polarization direction and can therefore pass through the polarizer 48 and are registered by the test camera 50 as changes in brightness.

[0067] One advantage of using a change-based inspection camera 50 or event camera is that it has a very high dynamic range and can detect even slight changes in brightness with a high frame rate. This eliminates the need to stop the containers 16 being inspected during the inspection process or to provide a mechanically complex tracking system for the container inspection device 42.

[0068] The evaluation unit 40 is connected to the test camera 50 and can receive the output signals generated by the test camera 50. The evaluation unit 40 checks the received output signals for the presence of local brightness variations. For this purpose, methods and procedures for pattern recognition, as already explained in detail, can be used. Subsequently, the evaluation unit 40 can determine a measure of the structural integrity of the container 16 under test, at least based on a detected local brightness variation and predefined test criteria. Finally, the container 16 under test is characterized with regard to its stability, at least based on the determined measure of structural integrity, using a test algorithm.Based on this characterization, a container stability signal is generated and transmitted at least to the control unit 30 of the filling device 28. The characterization of a particular container or bottle 16 can be carried out, for example, by assigning a stability parameter or by classifying the bottle 16 into different stability classes or categories.

[0069] In the event of detected container instability, the container stability signal can contain instructions for the control unit 30, which instructs the filling device 28 to fill the bottle 16 in a modified manner. This includes not filling the container 16 at all, filling it with a reduced quantity and / or pressure, performing a purge with a purge gas or pressurizing gas at a reduced pressure prior to filling, and / or not sealing the filled bottle 16. This prevents damage such as bottle bursting.

[0070] Should an unexpected damage event or bursting of bottle 16 occur due to an incorrect characterization, such as the bottle being erroneously characterized as stable or the modification of the filling process being insufficient, the control unit 30 generates an event parameter and transmits it to the evaluation unit 40. The evaluation unit 40 can use this event parameter to improve the test criteria and / or the test algorithm, thereby reducing the probability of such unexpected damage events occurring.

[0071] In the present embodiment, the testing system comprises a single container testing device 42. In variations not shown, two or more testing devices 42 may also be provided, which may be arranged at different positions along the conveying path 18. For example, it is conceivable to arrange a further container testing device 42 within the container cleaning device 22 and / or within the inspection device 24.

[0072] With reference to now Fig. 2 below explains how the stress required during the inspection of the containers 16 to be filled is generated.

[0073] Fig. Figure 2 shows a side view of the filling device 28. Fig. 1. The illustration of the filling device 28 in Fig. 2 differs in some details explained below from the representation of Fig. 1. For the sake of clarity, the filling device 28 is shown in a kind of unfolded view, which, however, does not depict the entire circumference of the annular filling device 28, but only a certain section. The inlet and outlet of the containers or bottles 16 do not take place on opposite sides of the circular filling device 28, but in a central area of Fig. 2, where the inlet and outlet are symbolized by corresponding curved arrows. The direction of rotation or conveying of the containers 16 in the filling device 28 is indicated by an arrow symbol.

[0074] The filling device 28 comprises an annular vessel 52, on the underside of which filling valves 54 are arranged at regular intervals. A conveying device 64 is associated with the filling device 28, which comprises a plurality of height-adjustable lifting plates 58. The lifting plates 58 are arranged corresponding to the filling valves 54 and rotate synchronously with the rotating annular vessel 52 in a circular path. The force required to lift and press the bottles 16 mounted on the lifting plates 56 can be applied by a pressing device (not shown). For example, in the illustrated embodiment, the lifting plates 56 can be pre-tensioned towards the annular vessel by means of spring force.

[0075] The lifting plate movement is controlled by a control cam 58, which interacts with rollers 66 located on the underside of the lifting plates 56. The control cam 58 has a contact section 60, which lifts and presses the bottles 16 against the filling valves 54 (e.g., by releasing a spring), and a lowering section 62, which, after filling, lowers the now filled bottles 66 (e.g., by re-tensioning the spring) and releases them from the filling valves 54. The rollers 66 of the lifting plates 56 are always in contact with the underside of the control cam 58, where the corresponding control sections are formed.

[0076] The container testing device 42 is arranged in an area where a respective container 16 comes into contact with the associated filling valve 54. By appropriately designing the contact section 60 with a suitable, only slightly changing inclination of the control surface, the contact force of the container 16 against the filling valve 54 can be increased by a predetermined gradient.

[0077] The container testing device 42 can be stationary. Alternatively, at least one tracking device can be provided, which enables swiveling and / or repositioning of the container testing device 42 or the testing camera 50. This allows the field of view of the testing camera 50 to be tracked according to the movement of the container 16 in the conveying direction and preferably also in the contact direction, so that an image of the container 16 to be tested on the image sensor of the testing camera 50 is essentially stationary, thus preventing changes in movement, focus, or brightness that are solely attributable to movement of the container 16 during the test.

[0078] The stress on the bottle 16 generated when pressing it against a filling valve 54 increases the stress on any existing structural anomalies, which, depending on the container material, also increases the influence on the polarization direction of the test light, in particular the degree of change in polarization direction, i.e. the angular change of the polarization direction, so that with increasing stress a higher proportion of test light passing through the relevant areas of structural damage is detected by the test camera 50.

[0079] The inspection system can further include means for tracking and / or identifying individual bottles 16 during their time in the filling plant 20 or at least within a specific area of ​​the filling plant 20. For this purpose, a shift register, for example, can be used. These tracking and / or identification means are preferably connected to the evaluation unit 40, enabling the evaluation unit 40 to track and / or identify each bottle 16 at least from the point of its inspection until the completion of the filling process in the filling device 28.

[0080] The characterization of the container stability can be carried out continuously, especially in the area of ​​increasing stress, so that if container instability becomes apparent, not only can the actual filling process of the container 16 be modified, but also other stress-inducing applications, e.g., the application of pressurizing gas, can be prematurely terminated.

[0081] The evaluation unit 40 can additionally receive at least one container parameter from the inspection device 24 as a result of the inspection, for example, a wear parameter such as the degree of scratching or a damage parameter. Furthermore, the evaluation unit 40 can receive one or more process parameters from the control unit 30 of the filling device 28, such as a (maximum) pre-charge pressure, a (maximum) filling pressure and / or the filling temperature, as well as, if applicable, an event parameter that characterizes a damage event occurring during the filling of a bottle 16. The event parameter can be generated, for example, by means of a damage detection system connected to or integrated into the filling device 28 (not shown).

[0082] The evaluation unit 40 can have a type of database or register in which the container parameters and / or process parameters determined for a given bottle 16, as well as any event parameter generated for that bottle 16 that characterizes a damage event affecting that bottle 16, are stored. This data can be stored for the duration of the bottle 16's stay in the filling system 20 or for a longer period to enable statistical analysis.

[0083] According to a further modification, the lighting device 44 and the test camera 50 can also be arranged in a reflection configuration in which the test light is reflected by the container 16 to be tested. This allows even non-transparent containers 16 to be tested for stability in accordance with the invention.

[0084] By testing the stability of the containers or bottles 16, taking into account container parameters, process parameters, and any event parameters that may occur, the probability of unwanted container bursts during the filling process is reduced preventively. The filling capacity of the filling system 20 is maximized by early sorting out or by modifying the filling process of potentially bursting containers 16, and the risk to personnel and end consumers from container fragments is reduced. Reference symbol list 16 containers, bottle 18 Conveyor route 20 bottling plant 22 Cleaning device 24 Inspection device 28 Filling device 30 Control unit 40 evaluation units 42 Container testing device 44 Lighting equipment 46, 48 Polarizer 50 inspection cameras 52 ring kettles 54 Filling valve 56 lifting plates 58 Tax backdrop 60 Contact section 62 Lowering section 64 Conveyor device 66 roll

Claims

[1] Method for testing containers (16) to be filled and identifying unstable containers (16) in a filling plant (20), comprising the following testing steps: - illuminating a container (16) to be tested with polarized test light, - detecting the inspection light reflected or transmitted by the container (16) to be inspected by means of a change-based inspection camera (50) having an image sensor configured to generate output signals exclusively in response to detected brightness changes, wherein the inspection camera (50) is assigned a polarizer (48) which is aligned such that the polarization direction of the light passing through the polarizer (48) differs from the polarization direction of the polarized inspection light, - checking the output signals generated by the test camera (50) for the presence of local brightness changes, - determining a measure of structural integrity of the container (16) to be tested at least on the basis of a detected local change in brightness and predetermined test criteria, and - characterising the stability of the container (16) to be tested at least on the basis of the determined degree of structural integrity using a test algorithm and generating a container stability signal based thereon, wherein the container (16) to be tested is subjected to stress during the testing, characterized by , that the stress is generated by a contact force which presses the container (16) against a filling valve (54) of a filling device (28) of the filling system (20). [2] Method according to claim 1, characterized by that the contact pressure is progressively increased during testing. [3] Method according to claim 2, characterized bythat if a potential container instability is detected, the progressive increase in the contact pressure is stopped immediately or when a predetermined threshold value is reached. [4] Method according to one of the preceding claims, characterized by in that, in order to compensate for a movement of the container (16) to be inspected during the detection of the test light, a received light path spanned between the moving container (16) and the image sensor is modified in such a way that the relative position of an image of the container (16) to be inspected on the image sensor does not change at least during a predetermined detection period. [5] Method according to claim 4, characterized by that at least one tracking device is provided, which - the test camera (50) and / or - a deflection device arranged in the received light path between the container to be inspected and the inspection camera (50) is moved translationally and / or rotationally at least during the detection period in such a way that the relative position of an image of the container (16) to be inspected on the image sensor does not change at least during the predetermined detection period. [6] Method according to claim 5, characterized by that at least one inspection camera (50) is arranged on the tracking device, wherein the tracking device moves the at least one inspection camera (50) continuously or discontinuously along a movement path. [7] Method according to claim 5 or 6, characterized by that the deflection device comprises a mirror, a polygon wheel or a prism wheel, wherein the tracking device is designed to rotate the deflection device with the same or periodically changing direction of rotation. [8] Method according to one of the preceding claims, characterized by that checking the output signals generated by the test camera (50) for the presence of local brightness changes comprises analyzing the output signals using pattern recognition methods. [9] Method according to one of the preceding claims, characterized by in that, in the event of a detected potential container instability, the container stability signal comprises instructions to the filling system (20) to fill the container (16) in question in a modified manner or to discharge the container (16) in question before filling. [10] Method according to claim 9, characterized by that the instructions to the filling device (28) include - not to fill the container (16) to be filled or to fill it with a reduced filling quantity and / or a reduced filling pressure, - to carry out a purge with a purge gas or pressure gas at a reduced pressure prior to filling and / or - not to close the filled container (16). [11] Testing system for testing containers (16) to be filled and identifying unstable containers (16) in a filling plant (20), comprising: (i) at least one container inspection device (42), wherein the container inspection device (42) comprises an illumination device (44) configured to illuminate a container (16) to be inspected with polarized inspection light, a change-based inspection camera (50) having an image sensor configured to generate output signals exclusively in response to detected brightness changes and provided for detecting the inspection light reflected or transmitted by the container (16) to be inspected, and a polarizer (48) assigned to the inspection camera (50), wherein the polarizer (48) is oriented such that the polarization direction of the light passing through the polarizer (48) differs from the polarization direction of the inspection light generated by the illumination device (44), and (ii) an evaluation unit (40) which is arranged to - checking output signals received from the container testing device (42) for the presence of local brightness changes, - to determine a measure of structural integrity of the container (16) to be tested at least on the basis of a detected local change in brightness and predetermined test criteria, and - to characterize the stability of the container (16) to be tested at least on the basis of the determined degree of structural integrity using a test algorithm and to generate a container stability signal based thereon, wherein the filling system (20) comprises at least one filling device (28) on which at least one container testing device (42) of the testing system is arranged, wherein the container (16) to be tested is subjected to stress during the testing, which stress is generated by a contact force that presses the container (16) against a filling valve (54) of the filling device (28).

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