Monitoring of the settings of heating devices in blow molding machines

Abstract

The invention relates to a method (100) for producing containers (207) from preforms (206) using a blow molding machine (200) comprising at least one temperature control device (201) and a forming device (202) with at least one forming station (203), wherein the preforms (206) are tempered by means of the temperature control device (201) based on predefinable setting values ​​of the temperature control device (201), and wherein each tempered preform (206) is formed into a container (207) by means of a forming station (203), and wherein changes in the setting values ​​of the temperature control device (201) are detected.

Description

Field of invention

[0001] The invention relates to a method for producing containers from preforms using a blow molding machine, and to a blow molding machine for producing containers from preforms. State of the art

[0002] It is known to use a method for the production of containers, in particular for the production of plastic containers, to form preforms made of a thermoplastic material, e.g. polyethylene terephthalate (PET), into containers by blow molding or stretch blow molding in forming stations of blow molding machines, wherein the blow molding machines have temperature control devices in which the preforms are tempered before their forming, in particular e.g. heated.

[0003] However, a disadvantage of known manufacturing processes and known blow molding machines is that consistently high quality of the manufactured containers for high production volumes, e.g. thousands of containers produced per hour, can only be achieved at a very high cost and production cost.

[0004] Furthermore, well-known manufacturing processes and blow molding machines are sometimes very prone to wear and tear, which can lead to undesirable production downtimes. Task

[0005] It is therefore an object of the invention to provide an improved method for manufacturing containers from preforms and an improved blow molding machine for manufacturing containers from preforms.

[0006] In particular, one object of the invention is to improve the efficiency of container manufacturing, as well as to improve the quality and grade of the manufactured containers and thus reduce the rejection rates of defective containers.

[0007] Furthermore, one of the aims of the invention is to minimize production downtime in container manufacturing. Solution

[0008] This is achieved according to the invention by the subject matter of the independent claims.

[0009] Advantageous embodiments and further developments are the subject of the dependent claims.

[0010] An exemplary method for manufacturing containers, e.g., plastic containers or plastic bottles, from preforms, in particular from preforms made of a thermoplastic material, e.g., polyethylene terephthalate (PET), using a blow molding machine, e.g., using a stretch blow molding machine, wherein the blow molding machine may have at least one temperature control device and a forming device with at least one forming station, may comprise one, some, or all of the following steps: • Temperature control, in particular heating, of the preforms, wherein the preforms are temperature controlled by means of the temperature control device based on predefinable setting values ​​of the temperature control device, in particular based on at least one predefinable setting value of the temperature control device, • forming a tempered preform into a container using a forming station of the blow molding machine, and • a detection of changes in the setting values ​​of the temperature control device, in particular detection of changes in at least one setting value of the temperature control device.

[0011] The detection of changes in the setting values ​​of the temperature control device can take place at any time during the process, in particular, for example, before, during or after the temperature control of the preforms.

[0012] Recording changes in the temperature control device settings can mean measuring, determining, or reading and storing these settings, for example, in a database. This recording, determination, and storage of the settings can be computer-assisted.

[0013] The term "setting values" for the temperature control device can refer to values ​​of settings or values ​​of parameters for setting and / or controlling and / or regulating the temperature control device.

[0014] Examples of settings include heating temperature settings, heating time settings, heating point settings, heating duration settings, heating power settings of the temperature control device or of elements of the temperature control device, e.g. heating elements.

[0015] The setting values ​​of the temperature control device can therefore include, for example, heating temperature values, heating time values, heating time values, heating duration values, heating power values ​​of the temperature control device or of elements of the temperature control device, e.g. heating elements.

[0016] It is also conceivable that the settings of the temperature control device refer to certain position settings of possible movable elements of the temperature control device, e.g., movable heating elements, which determine the spatial alignment or orientation of said possible movable elements of the temperature control device.

[0017] Consequently, the setting values ​​of the temperature control device can also include certain position values ​​of possible movable elements of the temperature control device, e.g., movable heating elements, which determine the spatial alignment or orientation of said possible movable elements of the temperature control device.

[0018] A change in a setting value can be understood, for example, as a difference between the changed setting value and the setting value before the change. However, it is also conceivable that a change in a setting value can be understood as the value of the changed setting value itself.

[0019] The method described above and exemplified herein allows for the monitoring of the settings or setpoints of the temperature control device over time and can detect changes in the settings or setpoints of the temperature control device, which may be caused, for example, by wear or malfunctions of the components of the temperature control device, at an early stage.

[0020] The aforementioned at least one forming station of the blow molding machine can, for example, have a multi-part mold with movable parts, e.g., two mold halves, wherein the mold can receive a preform and wherein a pressurized blowing fluid, e.g., blowing air, can be introduced into a received preform via the mold in order to be able to form the preform into a container by means of the pressurized blowing fluid.

[0021] The temperature control device can also be called a heating device or heating oven.

[0022] In other words, the method described above and here as an example enables monitoring of the temperature control settings of a blow molding machine during the production of the containers.

[0023] This allows, among other things, the detection, and in particular the early detection, of undesirable changes in the temperature control device's settings, which can have a detrimental effect on the properties of the temperature-controlled preforms and thus also on the quality and characteristics of the containers to be manufactured.

[0024] In the method described above and here as an example, at least one property of a finished container can be measured, e.g. by means of a measuring device or by means of measuring sensors.

[0025] Furthermore, taking into account or depending on the recorded at least one property of a finished container, at least one setting value of the temperature control device can be changed, or several setting values ​​of the temperature control device can be changed taking into account or depending on the recorded at least one property of the finished container.

[0026] The setting value changed taking into account or depending on the recorded at least one property of a finished container, or the setting values ​​changed depending on the recorded at least one property of a finished container, can influence said recorded property of a finished container with respect to desired container reference properties, so that the at least one container property of subsequently manufactured containers, which were manufactured with the changed setting value, is closer to or equal to a desired container reference property.

[0027] Therefore, feedback or a control loop can be implemented between the detected container properties and the setpoints of the temperature control device.

[0028] This ensures consistent quality and performance of the manufactured containers and prevents or minimizes undesirable deviations in the properties of manufactured containers from the desired target or reference properties. In other words, it guarantees that as many manufactured containers as possible exhibit the ideal desired quality.

[0029] Through this feedback loop between the measured container properties and the temperature control device settings, wear and tear on the blow molding machine or the temperature control device can be compensated for, at least for a certain period of time. For example, the temperature control device settings can be adjusted up to the wear limit or even to critical values ​​to ensure consistent quality of the manufactured containers within an acceptable tolerance range.

[0030] This can reduce the rejection rate of defective containers and / or the rejection rate of containers of insufficient quality or of containers with insufficient properties.

[0031] A critical setting value can, for example, be understood as a maximum or minimum setting value which, if exceeded or fallen below, can lead to damage to the temperature control device and / or damage to the preforms.

[0032] The metrological recording of at least one property of a completed container can be carried out for each completed container, e.g. by inline measurements or by offline measurement, or only for a selection of completed containers, e.g. only every second or only every tenth completed container.

[0033] The said possible recorded at least one property or characteristic of a finished container may be one of the following: a wall thickness of the container or a wall thickness distribution of the container or a crystallinity of the container or a geometry of the container or a weight of the container, in particular a section weight, or a transmission value.

[0034] Section weight can refer to, among other things, the weight of individual parts, areas or sections of a container, e.g. the weight of the bottom, belly and / or neck of the container or the weight of other sections of the container.

[0035] A transmission value can be understood in particular as a value that indicates how much light passes through the material of the container.

[0036] This value can be determined for different wavelengths of light, such as in the visible spectrum or the UV range. The transmission value can be measured, for example, with a spectrophotometer, which measures how much light passes through the material at different wavelengths.

[0037] To measure said at least one property of a finished container, the blow molding machine can have at least one measuring device which is designed to perform optical and / or acoustic measuring methods and / or other measuring methods adapted to the respective container property to be measured.

[0038] The measurement of the wall thickness of the container or the measurement of a wall thickness distribution of the container can be carried out, for example, by optical measuring methods, i.e., in particular those working with light waves and / or acoustic measuring methods, i.e., in particular those working with sound waves.

[0039] The crystallinity of the container can be measured using methods such as differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectroscopy (FTIR), polarization microscopy or density measurements.

[0040] The weight of the container can be determined, for example, by a scale, such as an analytical balance or a microbalance.

[0041] Section weights can be determined offline, for example. The container can be divided into several parts or sections, and the weight of each part or section can then be determined.

[0042] The geometry of the container can be measured, for example, using a measuring device designed as a camera.

[0043] In the process described above and here as an example, the temperature in the temperature control unit and / or the temperature of the preforms can also be measured. The blow molding machine or the temperature control unit can, for example, be equipped with a temperature sensor, which may be a pyrometer or thermal imaging camera.

[0044] The temperature(s) can therefore be measured, for example, with a pyrometer or a thermal imaging camera.

[0045] The temperature(s) can be measured at several points on the blow molding machine. For example, the temperature can be measured at the outlet of the temperature control unit and / or in deflection areas.

[0046] Furthermore, at least one setting value of the temperature control device can then be changed, taking into account or depending on the temperature of the temperature control device and / or taking into account or depending on the temperature of the preforms.

[0047] This can also help to ensure consistent quality and grade of the manufactured containers within an acceptable tolerance range.

[0048] In the method described above and herein by way of example, a fault condition of the temperature control device and / or a wear condition of the temperature control device can be determined on the basis of the recorded changes in the setting values ​​of the temperature control device, in particular on the basis of the recorded changes in at least one setting value of the temperature control device.

[0049] This allows for the early detection of faults and wear in components of the temperature control device, in order to take necessary repair and / or maintenance measures in a timely manner.

[0050] For example, this allows wear-related problems with heating elements of the temperature control device to be detected earlier and in a timely manner.

[0051] The older heating sources, such as infrared lamps, become, the more energy is required to achieve the same heating result. A detected change in the heating power settings of the heating sources can therefore indicate an aging heating source that is about to fail and need replacing.

[0052] The aforementioned exemplary fault condition of the temperature control device and / or the aforementioned exemplary wear condition of the temperature control device can be displayed on a display device, e.g. a digital display, wherein the output on the display device may also include a voice output of the specified wear condition and / or the specified fault condition of the temperature control device.

[0053] This can help to identify faults and wear in components of the temperature control device at an early stage, in order to be able to point out necessary repair and / or maintenance measures in a timely manner.

[0054] This allows necessary repair and / or maintenance measures to be initiated and carried out in a timely manner, for example to repair, maintain or replace aging heating sources of the temperature control device before the desired container quality can no longer be achieved.

[0055] This reduces production downtime, better protects the blow molding machine or temperature control device from damage, and ensures consistent container quality.

[0056] Alternatively or additionally, a signal, such as a notification, can be displayed on the aforementioned display device. For example, a notification, such as information on necessary repair and / or maintenance measures, can be sent to an employee responsible for maintenance. This can contribute to more efficient and effective maintenance.

[0057] The possible detection of changes in the setting values ​​of the temperature control device, or the possible detection of changes in at least one setting value of the temperature control device, can include the detection of the magnitude of the changes, e.g., the amount of the setting value changes, and / or the direction of the changes, e.g., increase or decrease of a setting value, and / or the number of changes and / or the frequency of the changes.

[0058] The potential detection of changes in the temperature control device's settings can also include detecting when critical setting value limits are reached.

[0059] For example, detecting when critical setting value limits are reached, e.g., reaching the maximum possible heating power of a heating element in the temperature control device, can also indicate possible critical fault conditions or critical wear conditions, so that necessary maintenance or repair can be indicated early and in a timely manner.

[0060] Other patterns in the temporal progression of the recorded changes in the setting values ​​of the temperature control device can also be recorded, stored and evaluated in order to draw conclusions about errors and wear in components of the temperature control device.

[0061] In the procedure described above and here as an example, all changes occurring in the setting values ​​of the temperature control device can be recorded and / or stored and / or evaluated at any time.

[0062] The recording of changes in the setting values ​​can therefore take place continuously or quasi-continuously or continuously and without interruption during the operation of the temperature control device or during the operation of the blow molding machine.

[0063] It is also conceivable that the recording of changes in the setting values ​​takes place at regular intervals, e.g. in the production cycle, or at irregular intervals.

[0064] In other words, it is conceivable that the recording of changes in the setting values ​​only takes place at predefined time intervals.

[0065] Detected changes in the temperature control device settings can be compared with the target values ​​of the settings.

[0066] For example, an actual value of the setting value or an actual value of the changed setting value can be compared with a target value of the setting value, and if an undesirable deviation is detected, the detected actual value of the setting value can be adjusted to the target value of the setting value.

[0067] Alternatively or additionally, it is conceivable that changes in the setting values ​​of the temperature control device are only recorded when predefinable threshold values ​​are undershot and / or only when they are exceeded.

[0068] For example, it is conceivable that changes in the temperature control device settings are only detected if the amount of the changes exceeds a threshold of 1% or 10% with respect to a target value or reference value of the setting.

[0069] All of the above and below exemplary process steps can be carried out fully automatically by a programmable digital control unit or supported by a programmable digital control unit.

[0070] In other words, all the process steps exemplified above and here can be carried out using a computer.

[0071] It is also conceivable that the temperature control device's settings could be changed and entered manually or semi-manually, e.g. by an operator of the blow molding machine.

[0072] The aforementioned exemplary control unit can be integrated into the blow molding machine or the temperature control device, or it can be an external control unit that communicates with the blow molding machine or the temperature control device.

[0073] Further exemplary aspects of the invention or exemplary aspects of the claim features are illustrated by the following figures.

[0074] An example of a blow molding machine for manufacturing containers from preforms may include the following components: • at least one temperature control device, • a forming device with at least one forming station, and • a programmable control device for controlling and / or regulating the temperature control device and the forming device with the forming station.

[0075] The control unit can be programmed and trained to carry out a process for manufacturing containers from preforms according to the process characteristics described above as examples.

[0076] The control unit can have a database or data storage device, or be in communication with a database or data storage device, in which all recorded changes in the setting values ​​of the temperature control device and / or all actual values ​​of the setting values ​​of the temperature control device as well as all target values ​​of the setting values ​​of the temperature control device can be stored and can be retrieved for evaluation.

[0077] Furthermore, the blow molding machine may have a measuring device for recording at least one property of a finished container, which, for example, can measure and determine one or all of the above-mentioned properties of a finished container.

[0078] In addition, the blow molding machine may have a measuring device for recording the temperature in the temperature control device and / or for recording the temperature of the preforms.

[0079] An exemplary temperature control device of the exemplary blow molding machine can include at least one heating source of the following type: laser source, infrared source, e.g. infrared lamp, microwave source. Fig. 1: Exemplary procedure Fig. 2: Example of a blowing machine

[0080] The Fig. Figure 1 presents an exemplary schematic flow diagram for a process 100 for the production of containers from preforms using a blow molding machine comprising at least one temperature control device and a forming device with at least one forming station.

[0081] In the exemplary process 100, the preforms are first tempered using the tempering device based on predefinable setting values ​​of the tempering device 101.

[0082] Subsequently, each tempered preform can be formed into a container using a forming station.

[0083] Changes in the setting values ​​of the temperature control device can be detected 103.

[0084] The detection of changes in the setting values ​​of the temperature control device can take place at any time during the process, in particular, for example, before, during or after the temperature control of the preforms.

[0085] The Fig. Figure 2 shows, schematically, an example of a blow molding machine 200 for the production of containers 207 from preforms 206.

[0086] The blow molding machine 200 comprises an exemplary tempering device 201 for the preforms 206 and a forming device 202 with at least one forming station 203 in which tempered preforms can be formed into containers.

[0087] The blow molding machine 200 also includes, for example, a measuring device 205 for recording at least one property of a finished container 207.

[0088] The blow molding machine 200 also includes, for example, a programmable control unit 204 for controlling and / or regulating the temperature control device 201 and the forming device 202 and the forming station 203.

[0089] The control unit 204 can also communicate with the measuring device 205.

[0090] The temperature control device 201 can include at least one heating source (not shown) of the following type: laser source, infrared source, e.g. infrared lamp, microwave source.

[0091] The following characters are Fig. 1 and Fig. 2.

[0092] The reference symbols are assigned as follows. 100 Exemplary methods for manufacturing containers from preforms 101, 102, 103 Exemplary procedural steps 200 Exemplary Blowing Machines 201 Exemplary temperature control device 202 Exemplary forming device 203 Exemplary forming station 204 Exemplary control device 205 Exemplary measuring device 206 Exemplary preform 207 Exemplary manufactured container

Claims

[1] Method (100) for producing containers (207) from preforms (206) using a blow molding machine (200) comprising at least one temperature control device (201) and a forming device (202) with at least one forming station (203), wherein the preforms (206) are tempered by means of the tempering device (201) based on predefinable setting values ​​of the tempering device (201), and wherein a tempered preform (206) is formed into a container (207) by means of a forming station (203), and wherein changes in the setting values ​​of the tempering device (201) are detected. [2] Method (100) according to the previous claim, wherein at least one property of a finished container (207) is measured and at least one setting value of the temperature control device (201) is changed taking into account the measured at least one property. [3] Method (100) according to the preceding claim, wherein the at least one property of a finished container (207) is one of the following properties: a wall thickness of the container or a wall thickness distribution of the container or a crystallinity of the container or a geometry of the container or a weight of the container, in particular a section weight of the container, or a transmission value. [4] Method (100) according to one of the preceding claims, wherein the temperature in the temperature control device (201) and / or the temperature of the preforms (206) is measured. [5] Method (100) according to the previous claim, wherein taking into account the detected temperature of the temperature control device (201) and / or taking into account the detected temperature of the preforms, at least one setting value of the temperature control device (201) is changed. [6] Method (100) according to one of the preceding claims, wherein, based on the detected changes in the setting values ​​of the temperature control device (201), a fault condition of the temperature control device (201) and / or a wear condition of the temperature control device (201) is determined. [7] Method (100) according to the preceding claim, wherein a fault condition of the temperature control device (201) and / or a wear condition of the temperature control device (201) is displayed on a display device and / or wherein a signal is displayed. [8] Method (100) according to any of the preceding claims, comprising the detection of changes in the setting values ​​of the temperature control device (201), the detection of the magnitude of the changes and / or the direction of the changes and / or the number of changes and / or the frequency of the changes. [9] Method (100) according to one of the preceding claims, wherein the changes in the setting values ​​of the temperature control device (201) are detected only when predefinable threshold values ​​are undershot and / or only when predefinable threshold values ​​are exceeded. [10] Method (100) according to one of the preceding claims, wherein the changes in the setting values ​​of the temperature control device (100) are only detected at predefinable time intervals. [11] Method (100) according to one of the preceding claims, wherein detected changes in the setting values ​​of the temperature control device (201) are compared with target values ​​of the setting values. [12] Blow molding machine (200) for the production of containers (207) from preforms (206) comprising: at least one temperature control device (201), a forming device (202) with at least one forming station (203), and a programmable control device (204) for controlling and / or regulating the temperature control device (201) and the forming device (202), wherein the control device (204) is programmed and configured to carry out a method (100) according to one of the preceding method claims. [13] Blowing machine (200) according to the previous claim, further comprising at least one measuring device (205) for detecting at least one property of a finished container (207). [14] Blow molding machine (200) according to one of the preceding blow molding machine claims further comprising a measuring device (205) for detecting the temperature in the tempering device (201) and / or for detecting the temperature of the preforms (206). [15] Blowing machine (200) according to one of the preceding blowing machine claims, wherein the temperature control device (201) comprises at least one heating source of the following type: laser source, infrared source, e.g. infrared lamp, microwave source.

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