Method for recording the operational behavior of a tank treatment plant

Abstract

The invention relates to a method for recording the operating behavior of a container treatment system with a treatment element (6) arranged to be longitudinally displaceable within a hollow body (4) and at least one drive unit (7) associated with the treatment element (6), which is designed as an electric drive. According to the invention, a drive parameter of the drive unit (7) is recorded and, based on the recorded drive parameter, at least one state parameter in the hollow body (4) is determined.

Description

[0001] The present invention relates to a method for recording the operating behavior of a container treatment system with a treatment means arranged longitudinally displaceable within a hollow body and initially a drive device associated with the treatment means, which is designed as an electric drive.

[0002] Such container treatment systems are known from the prior art, with particular reference to container treatment systems from the beverage industry. The containers to be treated in these systems are primarily beverage containers, such as beverage bottles, beverage cans, or plastic preforms from which beverage bottles are later formed. These plastic preforms are made of a thermoplastic material, especially polyethylene terephthalate (PET), and can thus be easily plastically deformed after heating. The beverage bottles themselves can also be made of plastic, especially polyethylene terephthalate. However, the beverage bottles can also be made of glass.

[0003] Within the scope of the invention, "treatment of the containers" is understood to mean any activity by which the containers are optically, mechanically, or chemically influenced in any way. Accordingly, this can include, for example, cleaning, sterilization, filling, or reshaping of a container. Labeling, sealing, and palletizing are also understood as treatment within the scope of the invention.

[0004] Ultimately, however, the treatment process always involves arranging a treatment device inside a hollow body, for which purpose this device is designed to be longitudinally displaceable and can be arranged inside the hollow body via a drive device.

[0005] The type of this equipment is not limited to a specific design. In particular, this equipment could be, for example, a so-called stretching bar, which is used in stretch blow molding. In this case, the container processing system is designed as a blow molding machine or at least includes a corresponding blow molding machine, whereby a plastic preform, in the sense of a container, is inserted into a blow mold and, by applying internal pressure, is formed into a beverage container, especially a beverage bottle. For this purpose, a treatment fluid is introduced into the container under pressure. This could be, for example, compressed air or a liquid filling medium that is already ready to be filled, the latter process also being referred to as the form-fill process.At the same time, a stretching bar is inserted along the container axis, causing axial elongation of the plastic preform.

[0006] Furthermore, it is known from practical experience that a variety of sensors are used to measure relevant condition parameters within the hollow body. This allows conclusions to be drawn about the progress of the treatment process as well as about the structural properties of the hollow body. For example, it is possible to obtain information about the pressure inside the hollow body by measuring the pressure during stretch blow molding. A sudden pressure drop, for instance, could indicate a bursting of the hollow body, while slight deviations could signal leaks during the introduction of the treatment fluid.

[0007] However, this method is currently relatively complex, as it requires the use of numerous sensors to draw conclusions about the state variables – such as the pressure inside the hollow body. It should also be considered that such container treatment plants often have many treatment stations operating simultaneously, meaning that a large number of hollow bodies are treated at the same time, and the state variables must therefore be measured for all of them. This method is comparatively complex and is therefore often only used at individual treatment stations.

[0008] Against this background, the invention is based on the objective of providing a method which allows conclusions to be drawn in a simple manner about the operating behavior of a container treatment plant.

[0009] The subject and solution of this problem is a method according to claim 1. According to the invention, it is provided that a drive parameter of the drive device is detected and at least one state parameter in the hollow body is determined on the basis of the detected drive parameter.

[0010] The drive parameter can be either a torque or a drive current of the drive device. Measuring a drive current, in particular, is a simple process. Torque can, of course, also be measured. However, these two drive parameters are closely related. A high drive current indicates a high torque, while a low drive current indicates that the drive device only needs to generate a low torque. Furthermore, it is also conceivable that the drive parameter is a torque, which is determined indirectly by measuring the drive current.

[0011] According to the invention, the drive parameter of the drive unit is measured during the processing of the treatment device, and at least one state parameter is derived based on this measurement. This state parameter can, for example, be a pressure inside the hollow body. Such a configuration is particularly relevant when the treatment device is a stretching bar of a stretch blow molding machine. It should be noted that during the stretching of the bar, the interior of the hollow body or the plastic preform is simultaneously pressurized. This pressure acts on the surface projected in the direction of the longitudinal displacement of the stretching bar and thus forms a resistance for the stretching bar.Accordingly, the drive unit, designed as an electric motor, must overcome greater resistance at higher pressures inside the hollow body than at lower pressures, thus requiring a higher torque and therefore a higher drive current.

[0012] Accordingly, the drive parameter can be compared with predefined drive parameters, where the predefined drive parameters are assigned to specific state variables. Thus, it is possible to determine a state variable based on the recorded drive parameter. The predefined drive parameters can, for example, be stored in tables, with these tables then correspondingly mapping them to the respective state variables.

[0013] According to a further development of the invention, the drive parameter is repeatedly acquired, at least during a time period, particularly a first time period, to determine a drive parameter profile, especially a torque profile or a drive current profile. Accordingly, this is not a single acquisition but rather a multiple acquisition within a specific time period, whereby a multitude of acquisitions of the drive parameter can be carried out within a predetermined time interval. This multiple measurement makes it possible not only to acquire individual values ​​as state parameters but also to determine changes in these values ​​or rates of change of these values. In this context, a rate of change is understood to be the ratio between a difference in value and the time interval.

[0014] Accordingly, the state parameters preferably consist of a pressure, a pressure change and / or a pressure change rate within the hollow body.

[0015] According to a further development of the invention, it is possible to determine characteristic operating events based on at least one determined state parameter or on the basis of the determined state parameters. In this context, characteristic operating events are understood to be operating events that are characteristic of the treatment process. For example, it is possible to use the determined state parameters to verify whether the treatment process is carried out as desired or whether individual relevant time intervals within the treatment process have been reached.

[0016] On the other hand, characteristic operational events can also involve malfunctions within the treatment process. In this case, the rate of change, particularly the pressure change rate, is of special interest. For example, if an unexpected pressure drop is observed, this could indicate a leak within the system or even a bursting of the hollow body. Crucially, a bursting of the hollow body is typically associated with a very sharp and rapid pressure drop, resulting in a correspondingly high pressure change rate. If such a high pressure change rate is not anticipated within the planned treatment sequence, a bursting of the hollow body can be inferred relatively clearly. This is particularly important during the stretch blow molding process.Leaks in the system, such as an incorrect connection between a plastic preform and a blow molding unit, lead to a comparatively low pressure change rate. Accordingly, it is possible to detect malfunctions by comparing the determined state parameters with predefined state parameters, with any deviation between the determined and predefined state parameters indicating a non-planned operational event.

[0017] Naturally, a fault tolerance can also be taken into account, so that not every minor deviation automatically constitutes a non-planned operational event. It is also possible to average several drive parameters recorded within a time period before comparing them with predefined state parameters. It is particularly advantageous if the drive parameters to be averaged are recorded within a sub-section of the time period, so that multiple determinations of the state parameters are still possible to identify changes or rates of change.

[0018] According to a preferred embodiment of the invention, it is further provided that at least one state parameter is additionally acquired directly. This is possible, for example, by means of a suitable measuring sensor. In addition to acquiring the drive parameter, this sensor can also directly acquire a state variable, e.g., pressure, so that the exact value for the state parameter is preferably determined by direct acquisition. Using the drive parameter, it is then possible to acquire changes or rates of change, e.g., pressure changes or rates of pressure change, as quickly as possible, so that, accordingly, only deviations from the directly measured value are detected using the drive parameter. At the same time, it is also possible to determine a comparison between the directly and indirectly acquired state parameter, thereby enabling conclusions to be drawn about the functions of individual sensors.

[0019] According to a further development of the method, the state inside the hollow body is influenced, in particular modified, based on at least one recorded state parameter. For example, it can be determined based on the determined state parameter that the pressure inside the hollow body drops during the relevant time period, so that the pressure inside the hollow body can be maintained accordingly by readjustment. This can be particularly relevant in a stretch blow molding machine, where the pressure present inside the hollow body is relevant for the quality of the forming of the plastic preform into a beverage bottle. Thus, if, for example, it is determined based on the drive parameter recording that the pressure cannot be maintained sufficiently inside the hollow body, the pressure can be increased or the pressure difference compensated for by supplying additional blow molding fluid.

[0020] According to a further development of the inventive method, it is also possible to determine at least one state parameter during a time period in which the treatment medium is not moving. This is a second time period, distinct from the first time period in which the drive parameter is acquired. Since determining the drive parameter is only possible when the treatment medium is moving, the time outside the first time period can be used to determine the state parameter. Because the time periods, particularly in stretch blow molding, may not be sufficient to directly influence the production step, the results obtained can be used to adjust the state within the hollow body in a subsequent production step.Therefore, if, for example, a leak is detected in the system during a first production step, a corresponding adjustment can then be made in a subsequent production step in which another container is treated.

[0021] According to a further development of the invention, the container treatment system comprises at least one stretch blow molding machine, wherein the hollow body is a container arranged within a blow mold, in particular a beverage container, and wherein the operating device is a stretching bar. This is a standard configuration of a stretch blow molding machine. Based on such a configuration, it can then be provided that the drive parameter is detected, in particular exclusively, during a production step in which the hollow body is pressurized with an internal pressure. In this context, internal pressure is understood to mean any pressure that is higher than the external pressure applied to the hollow body. Thus, it is possible to plastically deform the container using the internal pressure.

[0022] According to a further development of the invention, the hollow body is pressurized by introducing a treatment fluid. This fluid can be, for example, compressed air or a filling medium that is intended to be placed in the finished beverage bottle anyway. This filling medium is particularly liquid, e.g., a beverage or the like.

[0023] The invention further relates to a container treatment plant according to claim 11 for carrying out a method according to the invention, wherein the drive device for determining a drive parameter has a drive parameter sensor which is connected to an evaluation device and wherein the evaluation device is configured to determine at least one state parameter in the hollow body on the basis of the detected torque.

[0024] According to further training, the evaluation unit can be connected to a control unit, whereby the state inside the hollow body can be controlled or regulated via the control unit. In particular, the control unit can be configured to change the pressure inside the hollow body based on the detected state parameter.

[0025] According to a further development of the invention, a condition measurement sensor for directly measuring a condition parameter is operatively connected to the hollow body, in particular to the interior of the hollow body. This can, for example, be a pressure sensor for determining the pressure inside the hollow body.

[0026] The container processing system is, in particular, a stretch blow molding machine, or the container processing system includes a stretch blow molding machine, wherein the stretch blow molding machine has at least one blowing station, and wherein the blowing station is formed by a blow mold and a blowing unit associated with the blow mold. The blow mold preferably has at least two blow mold halves that can be pivoted relative to each other, which together form a blowing cavity on their inner surface when closed, corresponding to the shape of the beverage bottle to be produced. The blowing unit has, on the one hand, a blowing fluid supply which is operatively connected to the interior of the hollow body or the container during the production step.Furthermore, the treatment device, designed as a pull-up bar, is also longitudinally displaceable within the hollow body via the blowing device, with the drive device for the pull-up bar being arranged accordingly in the treatment device.

[0027] According to a further development of the invention, the drive device is an electric motor, in particular a servo motor. This can be, for example, a linear motor, e.g., a tubular linear motor, or a rotary servo motor with a linear spindle.

[0028] Furthermore, a preferred embodiment provides that a large number of identical blowing stations are arranged on a rotatably driven carrier, so that the containers are plastically formed into beverage bottles during rotary transport.

[0029] The invention is explained in more detail below using an exemplary initial example. The single figure shows a schematic representation of a stretch blow molding machine as part of a container treatment system. Only a relevant section of a treatment station 1 is shown, but according to the usual design, a plurality of identical blow molding stations 1 are arranged one behind the other in the circumferential direction on a rotatably driven carrier.

[0030] The blow molding station 1 consists of a blow mold 2 and a blowing unit 3 associated with the blow mold 2. The blow mold 2, in turn, consists of at least two blow mold halves that can be pivoted relative to each other, which together form a blowing cavity corresponding to the shape of the beverage bottle to be produced. A plastic preform in the form of a hollow body 4 is first inserted into this blow mold 2 and formed into a beverage bottle by applying internal pressure.

[0031] The internal pressure is applied via the blowing unit 3, which introduces a blowing fluid into the interior of the hollow body 4 via at least one blowing fluid supply line 5. This blowing fluid can be, for example, compressed air or the filling medium to be filled.

[0032] Furthermore, it is particularly known that during stretch blow molding, a stretching bar is moved along the container axis z as a treatment medium 6 during the production step. This step is particularly important for hollow bodies 4 made of polyethylene terephthalate, since the hollow body 4 can already be stretched along the container axis by means of the stretching bar, so that a radial expansion essentially occurs via the blowing fluid.

[0033] For the process of the treatment agent 6, the blowing device 3 has a drive device 7, which is designed as an electric motor, in particular as a servo motor.

[0034] The treatment medium 6 can be inserted into the hollow body 4 via the drive unit 7. During the production step, the pressure within the hollow body 4 opposes the treatment medium 6. Accordingly, a higher pressure requires a higher torque and a higher drive current from the drive unit 7 than a lower pressure. This fact can be used to indirectly determine a state parameter within the hollow body 4 by measuring the drive current or torque. This state parameter is, in particular, the pressure, a pressure change, or a pressure change rate within the hollow body 4.

[0035] For this purpose, the drive unit 7 is connected to an evaluation unit 8, which evaluates the measured drive current or torque and derives the corresponding state parameter from it. Multiple measurements of the drive current within a time period may be necessary for this. Based on the measured drive currents, a visual, optical, or other output can then be provided directly to a user. This may be particularly necessary if the evaluation unit 8 simultaneously performs a comparison with predefined state parameters. Should deviations be detected, this may indicate unplanned deviations from the planned process sequence. For example, an excessively rapid negative pressure change rate may indicate that the hollow body 4 has burst during exposure to the blowing fluid.Pressure changes that are not expected within a given time period can also indicate, for example, a leak in the system.

[0036] Furthermore, as shown in the figure, the evaluation unit 8 is connected to a control unit 9, via which, for example, a valve 10 in the blowing fluid line 5 or the drive unit 7 can be directly controlled. Accordingly, the operating process can be intervened in by determining the relevant state variables, so that, for example, more or less blowing fluid is introduced into the hollow body 4 or the bar is moved faster or in a different manner.

[0037] In addition, the treatment device 3 also provides a pressure measuring sensor 11, which is connected to the evaluation device 8, so that a direct measurement of the pressure can also be carried out. Reference symbol list 1 treatment ward 2 blow molds 3 Blowing device 4 hollow bodies 5. Blowing fluid supply 6 treatment products 7 Drive unit 8 Evaluation unit 9 Control unit 10 valve 11 Pressure sensor z container axis

Claims

[1] Method for recording the operating behavior of a container treatment plant with a treatment means (6) arranged longitudinally displaceable within a hollow body (4) and at least one drive device (7) associated with the treatment means (6), which is designed as an electric drive, characterized by , that a drive parameter of the drive device (7) is detected and at least one state parameter in the hollow body (4) is determined on the basis of the detected drive parameter. [2] Method according to claim 1, characterized by that the drive parameter is the drive current or a torque. [3] Method according to claim 1 or 2, characterized by , that at least during a period of time the drive parameters are recorded multiple times to determine a drive parameter profile. [4] Method according to any of the preceding claims, characterized by, that the state parameter is a pressure, a pressure change and / or a pressure change rate inside the hollow body (4). [5] Method according to any of the preceding claims, characterized by , that at least one additional state parameter is directly recorded. [6] Method according to any of the preceding claims, characterized by , that characteristic operating events are determined based on the identified state parameters. [7] Method according to any of the preceding claims, characterized by , that the state inside the hollow body (4) is influenced based on at least one recorded state parameter. [8] Method according to any of the preceding claims, wherein the determination of the at least one state parameter is carried out during a period of time in which the treatment agent (6) is not processed. [9] Method according to any of the preceding claims, characterized bythat the container treatment plant has at least one stretch blow molding machine and the hollow body (4) is a container arranged inside a blow mold (2), in particular a beverage container, and the operating equipment (6) is a stretch bar. [10] Method according to claim 9, characterized by , that the drive parameter is recorded during a production step in which the hollow body (4) is subjected to an internal pressure. [11] Method according to claim 10, characterized by that the internal pressure is applied by introducing a treatment fluid. [12] Container treatment plant for carrying out a method according to one of the preceding claims, wherein the drive device for determining the drive parameter has a drive sensor which is connected to an evaluation device (8) and wherein the evaluation device (8) is configured to determine at least one state parameter in the hollow body (4) on the basis of the detected drive parameter.

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