Injection molding device and method for determining state of injection molding device

Abstract

The invention relates to an injection molding device for producing molded parts and a corresponding method thereof. To this end, the injection molding device comprises an injection molding mold, a vibration sensor for measuring vibrations of the injection molding mold during a manufacturing cycle, a holder for accommodating the vibration sensor and holding the vibration sensor at a prescribed position on the injection molding mold, a control device for controlling the injection molding device, and an evaluation unit, the invention relates to an injection molding tool comprising an ejection side and a nozzle side, the ejection side and the nozzle side being movable relative to each other between a closed position in which the ejection side and the nozzle side are in contact and form a cavity, and an open position in which the support has an elastic element, the elastic element exerting a force on a vibration sensor, and the vibration sensor is arranged in the cavity. The evaluation unit is designed in such a way that the evaluation unit determines the state of the injection mold on the basis of the measured vibrations and on the basis of a control signal of the control device.

Description

Technical Field

[0001] The invention relates to an injection molding device and a method for determining a state of the injection molding device. Background Art

[0002] Common injection molding devices are known from the prior art, which are usually used to produce molded parts made of plastic. In particular, the core component of the injection molding device, namely the injection molding mold, must be maintained regularly. Usually, a preventive maintenance strategy is adopted. That is, maintenance is performed more frequently than necessary to ensure normal function and a sufficiently high quality of all finished molded parts. This preventive maintenance strategy is therefore extremely expensive in terms of time and cost. Summary of the invention

[0003] Therefore, the object of the present invention is to provide an injection molding device and a corresponding method, which can make it possible to use the injection molding device for a long time, especially technically, while the quality of the produced molded parts is stable.

[0004] This object is achieved by the subject matter of the independent claims. Advantageous developments of the invention are indicated in the dependent claims, the description and the drawings.

[0005] According to a first aspect of the invention, the task is accomplished by an injection molding device for manufacturing molded parts, the injection molding device comprising: an injection molding mold, a vibration sensor for measuring the vibration of the injection molding mold during a manufacturing cycle, a support for accommodating the vibration sensor and holding it at a specified position on the injection molding mold, a control device for controlling the injection molding device, and an evaluation unit, wherein the injection molding mold comprises an ejector side and a nozzle side. Here, the ejector side and the nozzle side can move relative to each other between a closed position and an open position, wherein the ejector side and the nozzle side are in contact in the closed position and form a cavity. The support has an elastic member, wherein the elastic member exerts a force on the vibration sensor, and wherein the evaluation unit is designed so that the evaluation unit determines the state of the injection molding mold based on the measured vibration and based on the control signal of the control device.

[0006] An important advantage of the injection molding device according to the invention is that, in particular by purposefully positioning the vibration sensor on the injection molding tool, the state of the injection molding tool can be inferred very accurately. In particular, by arranging the vibration sensor in the support according to the invention and applying force to the vibration sensor in the support via the elastic element, vibrations in the injection molding tool can be detected very accurately, so that the state of the injection molding tool can be determined very accurately. Since the state of the injection molding tool can be determined very accurately, the risk of unintentional shutdowns can also be reduced and downtimes can be shortened.

[0007] The vibrations measured can be structure-borne sound of the injection molding tool.

[0008] The evaluation unit can be designed in such a way that the states of other components of the injection molding device can also be determined, for example the injection unit of the injection molding device, in particular the state of the screw.

[0009] The vibration sensor may be designed such that it detects a vibration excursion that varies over time.

[0010] The vibration sensor may be a broadband sensor, preferably having a measuring range between 20 kHz and 450 kHz.

[0011] The force applied to the vibration sensor by the elastic member may be a constant preload.The vibration sensor may be arranged between the elastic member and the surface of the injection molding mold in the support.

[0012] The evaluation unit can be designed in such a way that it adjusts maintenance intervals of the injection molding device or of the injection molding mold as a function of the determined state of the injection molding mold.

[0013] Furthermore, the evaluation unit can be part of the control device, in particular a software component of the control device.

[0014] The determined injection molding mold state may be a wear state of the injection molding mold.

[0015] The ejection side and the nozzle side of the injection molding tool can be moved relative to one another in such a way that the ejection side is arranged to be movable and the nozzle side is arranged to be fixed.

[0016] According to one embodiment, the elastic member may be a disc spring, which is a very suitable elastic member because the disc spring has a very compact structure and a low manufacturing cost.

[0017] However, it is also conceivable to use other elastic elements, such as helical springs and / or rubber buffers.

[0018] According to one embodiment, the support can have a base plate and a housing. The housing and the base plate can have a plurality of through holes, which are used to thread the support with the injection molding mold. This threaded connection of the support with the injection molding mold allows the vibrations present in the injection molding mold to be transmitted very well to the vibration sensor installed in the support, thereby allowing the vibrations present in the injection molding mold to be measured very accurately, and thus allowing the state of the injection molding mold to be determined very accurately.

[0019] In this case, the base plate can be arranged between the housing and the injection molding tool in the assembled state.

[0020] Alternatively, the support can also be mounted on the injection molding mold by means of magnets and / or other fixing means.

[0021] In addition, a coupling agent, especially silicone grease, can be arranged between the base plate and the surface of the injection molding mold. This will reduce the vibration damping when the vibration is transmitted from the injection molding mold to the support or vibration sensor, thereby improving the vibration measurement accuracy.

[0022] It is also conceivable to arrange such a coupling agent between the base plate and the vibration sensor.

[0023] Furthermore, the damping between the injection molding tool and the support or the vibration sensor can be reduced by correspondingly optimizing, for example, the surface properties of the injection molding tool and the support. For example, it is conceivable that the surface has a low roughness.

[0024] According to one embodiment, the through holes can be arranged asymmetrically with respect to one another. This ensures that the support is mounted in a predetermined position in the injection mold with a predetermined orientation. Correct orientation and accurate reproducible mounting of the support or the vibration sensor ensures a very accurate determination of the injection mold state. The measurement result of the vibration sensor therefore depends in particular on the mounting position of the support or the vibration sensor, so that an accurate and reproducible positioning of the support or the vibration sensor can provide high-quality data that is easy to analyze.

[0025] According to one embodiment, the support, in particular the base plate, can be made of an electrically insulating material. Additionally or alternatively, the support can be designed such that the vibration sensor is electrically isolated from the injection molding mold in the installed state. This electrical isolation can be achieved by, in addition to using an electrically insulating material to make the support, also providing an additional electrical insulation between the support or the vibration sensor and the injection molding mold. This prevents the sensor from being influenced by other circuits that may be present in the injection molding device, thereby improving the quality of the measurement data of the vibration sensor and thus allowing a very accurate determination of the injection molding mold state.

[0026] According to one embodiment, the injection molding device may further comprise a pressure sensor for measuring the pressure in the cavity, wherein the evaluation unit is particularly designed such that the evaluation unit also determines the injection molding mold state based on the measured pressure. By additionally measuring and evaluating the pressure in the cavity formed by the injection molding mold, the injection molding mold state can be determined very accurately.

[0027] According to one embodiment, the injection molding device can have at least one further vibration sensor, wherein the evaluation unit is preferably designed such that the evaluation unit also determines the injection molding mold state based on the vibrations measured by the further vibration sensor, and wherein the injection molding device preferably has a further support that accommodates the further vibration sensor and holds it at a defined position on the injection molding mold. The additional use of at least one further vibration sensor allows the injection molding mold state to be determined very accurately, since the additional measurement data can reflect the conditions existing in the injection molding mold in more detail. In addition, by subjecting the data obtained with the aid of the vibration sensor and / or other vibration sensors to sensor data fusion, the quality of the information to be evaluated contained therein can be improved.

[0028] The other support may have the same structure as the support.

[0029] According to one embodiment, the vibration sensor and / or the further vibration sensor can be arranged on the ejection side, preferably at a distance from one another. The arrangement of the vibration sensor and / or the further vibration sensor on the ejection side allows vibrations occurring during the ejection of the molded part to be detected. Thus, a wider range of the production cycle of the molded part can be monitored and evaluated using the sensor, so that the state of the injection molding mold can be determined particularly accurately.

[0030] According to one embodiment, the vibration sensor and / or the further vibration sensor can be a piezoelectric sensor. With the aid of a piezoelectric vibration sensor, a particularly precise vibration measurement can be carried out in a very advantageous manner, so that the state of the injection molding tool can be determined particularly accurately.

[0031] Alternatively or additionally, the vibration sensor and / or the further vibration sensor may be an acceleration sensor, in particular a micro-electromechanical system (MEMS) sensor.

[0032] According to one embodiment, the injection molding device can have at least one further sensor, preferably a temperature sensor for measuring the temperature of the injection molding mold, wherein the evaluation unit is preferably designed such that the evaluation unit also determines the injection molding mold state based on the parameters measured by means of the further sensor, preferably the temperature sensor. The additional use of at least one further sensor, in particular a temperature sensor for measuring the temperature of the injection molding mold, allows the injection molding mold state to be determined particularly accurately, since the additional measurement data can reflect the conditions existing in the injection molding mold in more detail. In addition, by performing sensor data fusion on the data obtained by the vibration sensor and / or other sensors, the quality of the information to be evaluated contained therein can be improved. In particular, the measured injection molding mold temperature can allow the increased friction of the moving parts to be inferred.

[0033] Alternatively or additionally, the injection molding device may have a temperature sensor for measuring the temperature in the injection molding mold cavity.

[0034] Alternatively or additionally, the injection-molding device can have a temperature sensor for measuring the ambient temperature and / or the temperature of the coolant in the cooling circuit.

[0035] The temperature sensor can be a resistance temperature probe with a PT 100 sensor and / or a PT 1000 sensor.

[0036] According to a second aspect of the present invention, the object is achieved by a method for determining the state of an injection molding mold of an injection molding device according to the present invention, wherein the method comprises the following method steps: - Detect the vibration of the injection molding mold, -Especially to measure the pressure curve in the cavity, - in particular detecting the curve of another sensor signal, preferably the temperature curve of the injection molding mold, - Collect control signals from control devices, -Based on the acquired control signal, the measured vibrations are evaluated, preferably the pressure curve and / or other sensor signal curves, particularly preferably the temperature curve of the injection molding mold, wherein for each manufacturing cycle of the molded part, a spectrum is generated based on the measured vibrations, wherein the state of the injection molding mold is inferred based on the spectrum and the control signal, and preferably the pressure curve and / or other sensor signal curves, particularly preferably the temperature curve of the injection molding mold.

[0037] An important advantage of the method according to the invention for determining the state of an injection molding mold of an injection molding device according to the invention is that, in particular by detecting vibrations using a vibration sensor, the state of the injection molding mold can be inferred very accurately. In particular, by generating a spectrogram from the measured vibrations to evaluate the measured vibrations, the state of the injection molding mold can be inferred very efficiently. A large amount of data is generated when the vibrations are detected. By converting this data into a spectrogram, the amount of data can be significantly reduced. This in turn simplifies the subsequent evaluation of the spectrogram and increases its efficiency.

[0038] The spectrogram can be generated from the measured vibrations by means of a Fourier transformation, in particular a short-time Fourier transformation (STFT). The use of a Fourier transformation, in particular a short-time Fourier transformation (STFT), allows a very fast and therefore efficient generation of the spectrogram.

[0039] The measured vibrations and / or the acquired pressure curves and / or other acquired curves can be further processed in such a way that a large number of acquired data points, in particular every 100 data points, are aggregated by determining their average value or maximum value. This can further reduce the amount of data to be processed, making the evaluation of the acquired data more efficient.

[0040] Based on the control signal, it is preferably possible to draw conclusions about individual process phases of a molded part production cycle.

[0041] In addition, machine parameters of the injection molding device, in particular the injection time and / or the booster pressure time and / or the booster pressure and / or the booster pressure switching time, can be acquired. The acquired machine parameters can be taken into account when evaluating the measured vibrations and / or the acquired pressure curves and / or the acquired other sensor signal curves to infer the injection molding mold state.

[0042] The detected pressure curve and / or the detected other sensor signal curve can be a time-dependent curve within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Advantageous embodiments of the invention will be explained below with reference to the accompanying drawings, in which: Figure 1 A perspective view showing a support according to one embodiment of an injection molding device and a vibration sensor mounted thereon; Figure 2 Show according to Figure 1 A cross-sectional view of the support and the installed vibration sensor; Figure 3 Show according to Figure 1 The injection molding mold and the installed support. DETAILED DESCRIPTION

[0044] Figure 3An injection molding die 1 according to the invention is shown, which is integrated in an injection molding device (not shown). A support 3 is mounted on the injection molding die 1, which accommodates a vibration sensor 2 in the mounted state and holds it in a specified position. The injection molding die 1 basically has two sides, namely an ejector side 4 and a nozzle side 5, which can move relative to each other. In the closed position shown, the ejector side 4 and the nozzle side 5 form a cavity. The cavity can preferably be filled with injection molding material by means of a nozzle 10. Preferably, in the open position (not shown), the molded part formed by the cavity can be removed. In particular, the ejector side 4 can be movably arranged for this purpose, while the nozzle side 5 is fixedly arranged. In addition, the injection molding device has a control device (not shown) for controlling the injection molding device and an evaluation unit (not shown). The evaluation unit evaluates the vibration detected by the vibration sensor 2 based on the control signal of the control device and thus determines the state of the injection molding die 1.

[0045] The support 3 can be mounted on the ejection side 4 of the injection molding mold 1, such as Figure 3 As shown. Alternatively, the support 3 can also be installed on the nozzle side 5 of the injection molding mold 1. It is also conceivable to install two supports 3 and the vibration sensors 2 installed therein on the ejection side 4 and the nozzle side 5 of the injection molding mold 1. In addition, multiple supports 3 and the vibration sensors 2 installed therein can also be arranged in a dispersed manner on the ejection side 4 and / or the nozzle side 5 of the injection molding mold 1.

[0046] Especially from Figure 1 and Figure 2 It can be seen in FIG. 1 that the detailed structure of the support 3 is provided with the vibration sensor 2 installed. Figure 2 As shown, the support 3 has an elastic member 6. Figure 2 The elastic member shown is preferably a disc spring 6. Here, the elastic member 6 is arranged so that the elastic member 6 exerts a force on the vibration sensor 2. Figure 2 As shown in the exemplary embodiment, the disc spring 6 can be placed against the vibration sensor 2 for this purpose. For this purpose, the disc spring 6 or another elastic element 6 can be installed together with the vibration sensor 2 in the space defined by the support. Preferably, the disc spring 6 or the elastic element 6 exerts a constant force on the vibration sensor 2, particularly preferably towards the injection molding die 1. The support 3 preferably has a base plate 7 and a housing 8. In addition, the housing 8 and the base plate 7 preferably have through holes 9, so that the support 3 can be screwed to the injection molding die 1 by means of corresponding screws, such as Figure 3 For this purpose, the screw is screwed into the injection mold 1 through the through hole 9. The base plate 7 is preferably arranged on the injection mold 1, wherein silicone grease is particularly preferably applied between the surface of the injection mold 1 and the base plate 7, so that the vibration is transmitted from the injection mold 1 to the support 3 and finally to the vibration sensor 2 in an optimized manner.

[0047] Particularly important is the correct placement and orientation of the support 3 on the injection molding die 1. This can be ensured, for example, by an asymmetrical arrangement of the through holes 9, but this arrangement is not shown in the figures. This asymmetrical arrangement of the through holes and the corresponding threaded holes in the injection molding die 1 ensure that the support 3 can only be mounted on the injection molding die 1 in a defined position.

[0048] In addition, Figure 1 As shown, the housing 8 of the support 3 can have a recess 11 which allows the vibration sensor 2 to be connected by means of a cable in the installed state.

[0049] Preferably, the vibration sensor 2 is a piezoelectric sensor. Such a piezoelectric vibration sensor 2 may have a substantially cylindrical shape, such as Figure 1 and Figure 2 As shown. Alternatively, the vibration sensor 2 can be placed directly on the base plate 7. It is particularly preferred to electrically isolate the vibration sensor 2 from the injection molding die 1. In the embodiment shown in the figure, the support 3, in particular the base plate 7, is preferably at least partially made of a non-conductive material. The base plate 7 can therefore be made of polished steel, but it can have a ceramic plate as a contact surface for the vibration sensor.

[0050] Preferably, the injection molding device has one or more additional sensors, such as a temperature sensor for measuring the temperature of the injection molding mold or a pressure sensor for measuring the pressure in the mold cavity. These additional sensors are not shown in the figures. For example, it is conceivable to arrange the pressure sensor in the mold cavity or in the nozzle 10. The temperature sensor can be placed on the surface of the injection molding mold 1, for example.

[0051] The figures are only schematic and serve only to explain the invention. Identical or identically acting components are always provided with the same reference numerals.

[0052] Reference numerals list 1Injection molding mold 2Vibration Sensor 3 Support 4 Ejector side 5 Nozzle side 6 Elastic parts 7 Bottom Plate 8 Shell 9 Through Holes 10 Nozzles 11Gap

Claims

1. An injection molding device for manufacturing a molded part, comprising: - Injection molding die (1), - a vibration sensor (2) for measuring the vibration of the injection molding mold (1) during the manufacturing cycle, - a support (3) for receiving the vibration sensor (2) and holding it in a defined position on the injection molding mold (1), - a control device for controlling the injection molding device, and - Evaluation unit, The injection molding mold (1) comprises an ejection side (4) and a nozzle side (5). The ejection side (4) and the nozzle side (5) are movable relative to each other between a closed position and an open position. wherein the ejection side (4) and the nozzle side (5) are in contact in the closed position and form a cavity, Wherein, the support (3) comprises an elastic member (6), The elastic member (6) applies force to the vibration sensor (2), and Therein, the evaluation unit is designed such that it determines the state of the injection molding tool (1) based on the measured vibrations and based on the control signal of the control device.

2. The injection molding device according to claim 1, wherein: The elastic member (6) is a disc spring.

3. Injection molding device according to one of the preceding claims, wherein: The support (3) comprises a base plate (7) and a shell (8), and The housing (8) and the base plate (7) have a plurality of through holes (9) for threadedly connecting the support (3) to the injection molding mold (1).

4. The injection molding device according to claim 3, wherein: The through holes (9) are arranged asymmetrically with respect to each other.

5. Injection molding device according to one of the preceding claims, wherein: The support (3), in particular the base plate (7), is made of an electrically insulating material, and / or The support (3) is designed such that the vibration sensor (2) is electrically isolated from the injection molding die (1) in an installed state.

6. Injection molding device according to one of the preceding claims, comprising a pressure sensor for measuring the pressure in the cavity, wherein: The evaluation unit is designed such that it also determines the state of the injection molding tool (1) based on the measured pressure.

7. Injection molding device according to one of the preceding claims, wherein: The injection molding device comprises at least one further vibration sensor, wherein the evaluation unit is designed such that it also determines the state of the injection molding mold (1) based on the vibrations measured by means of the further vibration sensor, and The injection molding device preferably comprises another support, which accommodates the other vibration sensor and holds it at a specified position on the injection molding mold (1).

8. Injection molding device according to one of the preceding claims, wherein: The vibration sensor (2) and / or the further vibration sensor are arranged on the ejection side (4), preferably spaced apart from one another on the ejection side (4).

9. Injection molding device according to one of the preceding claims, wherein: The vibration sensor (2) and / or the further vibration sensor is a piezoelectric sensor.

10. Injection molding device according to one of the preceding claims, wherein: The injection molding device comprises at least one further sensor, preferably a temperature sensor for measuring the temperature of the injection molding mold, and Therein, the evaluation unit is designed such that it also determines the state of the injection molding tool (1) based on the parameter measured by means of the further sensor, wherein the further sensor is preferably a temperature sensor.

11. A method for determining a state of an injection molding device according to one of the preceding claims, wherein: The method comprises the following method steps: - detecting the vibration of the injection molding die (1), - collecting control signals of the control device, - evaluating the measured vibrations based on the acquired control signals, For each manufacturing cycle of the molded part, a spectrum is generated based on the measured vibration. Wherein, the state of the injection molding mold (1) is inferred based on the spectrum and the control signal.

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