DE102017003661A1 - Plastic molding process and molding machine - Google Patents

Abstract

Device for detecting soiling of a molding tool (2) used in molding cycles for producing a plastic component, comprising - at least one measuring device (3) for detecting physical properties of the molding tool (2) and / or a surface (25) altered by the contamination after a molding cycle ) of the molding tool (2) and - an evaluation unit (4) connected to the at least one measuring device (3), which is designed to transmit measured values of the at least one measuring device (3) and / or contamination data created from the measured values via an interface (5). issue.

Description

The present invention relates to plastic molding methods and molding machines.

Under shaping machines are injection molding machines, transfer molding, pressing and the like to understand.

In various molding processes for the production of plastic components, for example in the production of fiber plastic composites by a reactive process, such as resin injection method (RTM), SMC (sheet molding compound) or anionic Lactampolymerisation, it comes to process-related contamination of the tool. This contamination can consist of both plastic and monomer residues, as well as fiber and release agent residues. Due to the process control and the usual geometric design of shaping tools as well as sealing concepts, these contaminations particularly occur in the edge regions of the tool or the cavities; in injection methods (RTM or lactam polymerization), in particular at the end of the flow path.

Since these contaminations hinder the further production of components and especially soiling of the seal or any dipping edges can strongly negatively influence the flow behavior of the plastic or of the reactive system or even damage the tool, it is necessary to cyclically remove these residues. Depending on the specific process conditions, this cleaning must be done after each molding cycle or after a certain number of molding cycles. Often, this cleaning process is performed by a worker using brushes, spatulas, compressed air, etc. The optical control by the worker is of crucial importance. If you want to operate the process fully automated so you have the problem that the degree of contamination and the adhesion of pollution from molding cycle to molding cycle are not reproducible. Further, from molding cycle to molding cycle, layers of commonly used mold release agents may build up.

All common, fully automated solutions, such as a rotating brush guided by the robot, can not reliably guarantee that the tool has been cleaned without residue. Also, the degree of adhesion of residues can be so severe that such cleaning methods can no longer completely eliminate the contamination. A feedback on the success of the cleaning is not given according to the current state of the art, which makes a further control of the cleaning state and any manual rework by the worker indispensable. In some cases, residues may only consist of a very thin, transparent layer of plastic that is difficult for the human eye to detect. The danger of such residues being overlooked by the operator is given, which can significantly affect the next molding cycle.

It is known to manually clean shaping tools for, in particular, molding processes for the production of fiber-reinforced plastic composite components with reactive process control after each molding cycle or periodically. Since such methods were mainly used in the past with only a small number of pieces with an uncritical cycle time, this solution was practicable and economically justifiable. After a purely visual inspection of the tool, the worker must, with the help of various aids such as brushes, spatula, compressed air, etc., clean the tool, especially in the edge or sealing area, due to the process control and tool geometry. Optionally, an additional release agent can be done manually by the worker. The production process stops for the entire duration of the cleaning.

In order to increase productivity as the number of units increases, semi-automatic or fully automatic process management is becoming more and more important, reducing the cost-intensive use of personnel. The cleaning process can also be carried out automatically in this case. For example, a cleaning device can be guided by a robot. The device itself may consist of a brush system.

In Scripture DE 10 2013 109 858 A1 For example, a device for cleaning a tool for the production of moldings is described which is characterized in that in the cleaning device, the cleaning agent, for. B. brushes, are arranged movable along a guideway, wherein the guideway corresponds in parts or substantially the tool contour of a mold half. The device must always be created tool-specific.

The font DE 10 2013 109 859 A1 essentially describes a transfer system which makes it possible to move a cleaning device with cleaning agents in and out of a shaping machine, for example by means of a transfer system, in such a way that both the upper and the lower tool halves can be cleaned accordingly.

Instead of brushing you can also work with compressed air. In Scripture DE 38 37 257 A1 a device for cleaning a mold by means of blowing nozzles to assist the cleaning process is described.

Also known is a variety of off-line cleaning methods that require removal of the forming tool. Examples include cleaning with solid-state or diode lasers, ultrasonic or cleaning baths and various blasting methods, such as sandblasting mentioned.

Alternatively, tool coatings can be used which prevent deposits and replace the cutting of the tool. The font EP1301286 B1 describes the application of a permanent polymeric Entformungsschicht by plasma polymerization, which should largely replace the separation during the process.

The relatively complex, manual cleaning, in addition to staff deployment also requires a relatively long downtime because during the cleaning of the production process must be suspended. This is no longer acceptable given the demand for high productivity in the production of large quantities. The cleaning process must be fully or at least partially automated in order to be able to serve large series.

Downtimes also occur in all off-line cleaning processes such as cleaning in an ultrasonic bath or cleaning with blasting, since the tool must be removed and not available for the duration of the cleaning. Cyclic cleaning after each molding cycle is not economically feasible with these methods. They are only for basic cleaning in question.

All device-guided procedures, such as the use of cleaning agents such as brushes, lasers or compressed air have some disadvantages. Since the degree of contamination and its local distribution as well as the degree of adhesion are not reproducible, it can not be ensured that really all contaminations are reliably removed. So some areas of the tool would require a higher cleaning effort, other areas for little or no cleaning. All known devices are not able to differentiate here accordingly, which on the one hand leads to an increased expenditure of time due to the cleaning of actually clean spots and on the other hand brings with it the risk of residual dirt. Also, there is a higher load on the tool, the seal and the sensors installed in the tool through the cleaning process. So it is necessary a worker who checks the cleaning result after the cleaning cycle and optionally reworked. Especially with very thin, transparent plastic residues such as in the resin injection process often to observe sealing edges, there is a risk that they are not detected by the human eye and remain in the tool.

Although the use of special tool coatings temporarily prevents the adhesion of residues, loose residues can still remain in the mold and require a separate cleaning process. Furthermore, the provision of a tool of such a coating is complex, costly and possible only with special equipment. For coatings, there is always the risk that these are not permanent, a periodic renewal must therefore also often be carried out externally which in turn brings the need to expand the tool and send it externally.

All known, automated methods have the disadvantage that it always comes only to a more or less general cleaning, which can ensure process reliability.

The object of the invention is therefore to provide an apparatus and a method for cleaning the mold, which offer a higher process reliability and still allow automation.

This object is achieved by a device for the detection of soiling according to the features of claim 1 and a method for the detection of soiling according to the features of claim 12.

• – zumindest ein Messgerät zur Detektion von durch die Verschmutzung nach einem Formgebungszyklus veränderten physikalischen Eigenschaften des Formwerkzeugs und/oder einer Oberfläche des Formwerkzeugs und
• – eine mit dem zumindest einen Messgerät verbundene Auswerteeinheit, welche dazu ausgebildet ist, Messwerte des zumindest einen Messgeräts und/oder aus den Messwerten erstellte Verschmutzungsdaten über eine Schnittstelle auszugeben.

With respect to the device, this is done by

• At least one measuring device for detecting physical properties of the molding tool and / or a surface of the molding tool which are changed by the contamination after a shaping cycle, and
• An evaluation unit connected to the at least one measuring device, which is designed to output measured values of the at least one measuring device and / or contamination data created from the measured values via an interface.

• – Verschmutzungen nach einem Formgebungszyklus mittels wenigstens eines Messgeräts zur Detektion von durch die Verschmutzung veränderten physikalischen Eigenschaften des Formwerkzeugs und/oder einer Oberfläche des Formwerkzeugs detektiert werden und
• – Messwerte des zumindest einen Messgeräts und/oder aus den Messwerten erstellte Verschmutzungsdaten ausgegeben werden.

With respect to the method, this is achieved by:

• Contaminants are detected after a shaping cycle by means of at least one measuring device for detecting physical properties of the molding tool and / or a surface of the molding tool modified by the contamination, and
• Measurement values of the at least one measuring device and / or contamination data created from the measured values are output.

The invention thus describes a method for the detection of impurities on the surface of shaping tools, in particular usable in the production of fiber-reinforced plastic composite components. The detection of the impurities may be based on contact or distance-dependent electrical or electromagnetic methods such as resistance measurement, eddy current measurement or inductive measurement. In combination with a cleaning agent, the process can be extended to a device that enables efficient and reliable tool cleaning.

The detection of the contamination may preferably be resistive (resistance or passage measurement), inductive or by means of an eddy current measurement.

The altered physical properties may be those physical properties that have a direct impact on the molding process, such as a thickness of a soil layer that would affect the shape of the plastic components produced. But it can also be a physical property that is normally independent of the forming process, such as electromagnetic properties.

For the detection of contamination, a reference measurement can be used for comparison, which was recorded with an unpolluted mold.

A movement device may be provided which is designed to move and arrange the at least one measuring device after a shaping cycle in such a way that a potentially soiled area of the molding tool can be detected by the at least one measuring device. In particular, the device can be moved between the two mold halves. This makes it possible to bring the at least one measuring device closer to the potentially soiled areas, which in some cases can increase the accuracy of the measurement.

A movement along a previously defined trajectory can also take place in order to be able to detect a plurality of regions of the molding tool.

However, a movement of the at least one measuring device can also be done manually.

The movement device can be designed, for example, as a handling robot.

The at least one measuring device can be designed to carry out an inductive, resistive, magnetic and / or capacitive detection method.

The at least one measuring device can have a sliding contact, a magnet, a measuring coil and / or a Hall sensor. In particular, sliding contacts can be sprung mounted to adapt to the surface of the mold.

At least two measuring devices may be provided, which are designed to detect contamination at different points of the forming tool. As a result, not only can it be determined that there is contamination, but it can also be determined which region of the molding tool is dirty.

For this purpose, the at least two measuring devices can be arranged substantially in a line or a surface and be stored together in this way. The (imaginary) line or the surface (can also be referred to as "array"), on which the at least two measuring devices are arranged, can thereby be curved, in particular in order to achieve an adaptation to the contour of the molding tool.

The at least two measuring devices mounted in common therewith can be guided or moved over the molding tool for the purpose of detecting soiling via predefined trajectories. About the time at which a contamination is detected, then a spatial information about the pollution can be generated and passed through the interface.

A cleaning device, which is designed to clean the molding tool, can be integrated into the device according to the invention, and the device can be designed to output the measured values and / or the contamination data to the cleaning device via the interface. The cleaning device can then perform automated cleaning, for example, exactly at the polluted areas.

However, it is also possible to carry out at least one cleaning of the mold before or during the detection of the physical properties of the mold changed by the soiling. For example, one after the Cleaning carried out detection of cleaning verification serve. For example, if certain areas of the mold are cleaned independently of the detection, a simultaneous cleaning with the detection may also be advantageous in order to check whether other areas are also to be cleaned.

Of course, the cleaning of the entire mold may be provided.

The cleaning device may have cleaning agents such as lasers, brushes, spatulas, compressed air, and the like.

The apparatus may also have an applicator device adapted to apply a release agent to the mold to facilitate demolding and to prevent the formation of soils. This can also be done simultaneously with the cleaning or the detection. This offers the advantage that particularly often or stubbornly soiled areas can be individually treated with the release agent.

In addition, a suction device can be provided which can suck off excess release agent and / or aerosols, particles and the like obtained during the cleaning.

The interface may include a visualization device - in particular a screen - by means of which the detected contamination can be visualized for a human. The visualization can be done on a machine control of the molding machine or separately.

In a preferred embodiment, the determined measured values can be compared with reference measured values on the forming tool in a cleaned state. This reference measurement can take place once, but also cyclically before each shaping cycle.

A combination of one of these embodiments with a downstream automatic or manual cleaning process may be particularly preferred.

Protection is also desired for a molding machine having a device according to the invention and a plastic molding process, wherein plastic parts are produced in molding cycles, preferably by means of a reactive molding process, and a process according to the invention is carried out.

Further advantages and details of the invention will become apparent from the figures and the associated description of the figures. Showing:

1 and 2 Illustrations for illustrating a method according to the invention and an embodiment of a device according to the invention,

3 to 7 Representations of further embodiments of a device according to the invention,

8th an illustration of a shaping machine according to the invention and

9 a representation of another embodiment of the invention.

A possible method for the detection of soiling, in particular advantageous for the determination of electrically insulating contaminants on tools made of an electrically conductive material, works on the basis of a resistive measurement. In the resistive measurement according to the 1 and 2 Do you make the electrically insulating property of the contaminants 28 (in particular plastic dirt) to use.

For this are on a bracket 21 the device 1 several sliding contacts 7 (numbered as S ₁ to S _n ) attached, which meters 3 form (left representations of 1 and 2 ). These sliding contacts 7 are in contact with the surface 25 of the mold 2 , In the right representations of the 1 and 2 is the electrical connection of the sliding contacts 7 in the evaluation unit 4 shown.

About the voltage source 26 the source voltage U _{q is} applied between the contacts S ₁ and S ₂ to S _n . In the decision block 27 the contacts S2 to Sn are ANDed, which causes the output signal at the interface 5 is produced.

As long as all sliding contacts 7 with the metallic surface 25 of the mold 2 are in conductive contact, they also provide an electrical signal (Bei 1 without soiling "1"). Will be one of the sliding contacts 7 about a pollution 28 to 2 led, it comes through their insulating property to interrupt the electrical signal, which is detected (with pollution: "0"). So there is the information that pollution 28 of the mold 2 is available.

It should be noted that the sprung mounting of the sliding contacts 7 each by means of a spring 22 ensures that the device according to the invention 1 not on dirt 28 gets stuck or even gets damaged. Furthermore, it is achieved by the spring-mounted storage that the sliding contacts 7 the surface 25 of the mold 2 to adjust. The sliding contacts 7 can also be evaluated individually. This can be a pollution 28 be identified locally, ie detected spatially resolved. Any number of such contacts S ₁ to S _{n can be} arranged.

In an advantageous embodiment, the sliding contacts 7 arranged in a line and according to an exemplary device 3 , for example from a robot over the mold 2 be guided.

3 shows an embodiment of the invention, in which a cleaning device 8th is integrated. The cleaning device 8th has an example of a brush 31 as a cleaning agent.

The sliding contact 7 is also intrinsically resilient designed as a leaf spring.

Another embodiment of the contamination detection is based on a magnetic-inductive measuring principle 4 , This is particularly advantageous when the mold 2 consists of a ferromagnetic material. In the inductive measurement is using a resonant circuit 35 (Oscillator) generates a magnetic field by applying a voltage. The resonant circuit 35 is in 4 shown purely schematically.

Through a ferrite core in the coil, this magnetic field in the desired direction, ie in the direction of the surface 25 of the mold 2 directed. If an actuating object passes the sensor, energy is withdrawn from the oscillator and the oscillator voltage drops. Is the sensor over a pollution 28 led, results in a different oscillator voltage than when the sensor on the clean surface 25 to be led. With the help of a comparator 36 This voltage change can be detected and set a corresponding output stage relative to a definable switching threshold, causing the pollution 28 is detected and a corresponding signal is sent via the interface 5 output.

Another in 5 illustrated embodiment of the invention is based on a magnetic measuring method. This is particularly advantageous if the mold used 2 on what soils 28 to be detected, consists of a magnetic, in particular a ferromagnetic, material. The measured variable here is the required withdrawal force of a magnet 37 (Permanent or electromagnet) which from the surface 25 of the mold 2 or the underlying contamination 28 removed or subtracted. The adhesive or required withdrawal force is dependent on the material of the tool body and on the thickness of the soil layer. The dependence on the tool base body can be here by a reference measurement of the non-contaminated mold 2 eliminate. A contamination of the mold 2 thus expresses itself by a lower withdrawal force.

Another in 6 illustrated embodiment of the invention is based on an eddy current method. This is particularly advantageous when the mold 2 consists of a metallic, but not magnetizable material. The following explains the basic principle:
By applying an alternating current is in a measuring coil 38 generates an alternating magnetic field and thus induces eddy currents in the tool material. This in turn leads to the modulation of the magnetic field of the coil and to a reduction of the inductance. The influencing variable is the change of the inductive resistance of the measuring coil 38 through the layer thickness of the pollution 28 , For use as a detection method, this can be done, for example, by arranging the measuring coil 38 in a resonant circuit 35 be detected.

Also in this embodiment is given a, albeit constant, dependence on the tool material, which can be eliminated, for example, with a reference measurement. This reference measurement can take place once, but also cyclically before each shaping cycle.

In 7 is a version with a Hall sensor 39 for measuring a component of a magnetic field at the location of the Hall probe 39 shown. Because soiling 28 also change the already existing magnetic field, causing the pollution 28 can be detected. Thus, no additional magnetic field is generated as in the embodiments below 4 to 6 , That with non-polluted mold 2 existing magnetic field can - be determined by a reference measurement - as in the previous embodiments.

In a particularly preferred embodiment, detection methods described above can be implemented in such a way by the respective measuring devices (sliding contacts, magnets, measuring coils, Hall sensors, ...) are arranged over a large area on a die or an array which plate-shaped, or even parts of , or the entire topology of the tool is modeled. With a handling device as a movement device can be with this template automated start the top and / or bottom of the mold.

In particular, when replicating the tool topology by the array, this embodiment has the advantage that the detection of contamination can be done very quickly.

In an alternative embodiment, the detection methods can be used in such a way, in which the measuring means described by means of a moving device 6 be guided over one or both mold halves or parts thereof. This can be done for example by means of a previously programmed trajectory. As in 5 illustrated, the moving device may be designed as a handling device or handling robot.

5 shows a molding machine 11 with a device according to the invention 1 , the interface 5 can connect to a machine control of the molding machine 11 produce.

The result of the detection can be evaluated using the machine control and visualized as needed. In such an embodiment, the operator may be informed by the machine control of the molding machine about the local or overall cleaning or soiling condition of the molding tool 2 be informed.

Of course, a visualization can be provided separately from the machine control.

The inventive method can be carried out in combination with an upstream and / or downstream mold cleaning with one or more cleaning agents, for example one or more lasers, brushes, spatulas or compressed air. Detection and cleaning process can work together in one device 1 , but also be realized in separate devices.

The local application of mold release agents (release agents) or cleaners, before, during or after cleaning may also be provided. Particularly preferred in this case is an application of the corresponding release agent on a cleaning brush 31 to 5 and 6 and thus a combination of cleaning process and release agent application.

For the application of the release agent is an applicator 9 provided, which one from a reservoir 44 charged nozzle 43 having. As 6 can be seen, the release agent is through the nozzle 43 on the brush 31 sprayed and through the brush 31 on the surface 25 of the mold 2 applied.

For refilling the storage tank 44 the application device has a release agent supply 45 which, for example, via a tank 42 and a line 41 can be fed (see 5 ).

It can also be a suction device 46 be provided, which can suck off excess release agent and / or resulting in cleaning aerosols, particles and the like.

With the information obtained from the contamination detection, it is possible to partially clean only the soiled areas with the required intensity and then to verify the result fully automatically. Not only the cycle time is shortened significantly, also the surface 25 of the mold 2 , Seals and tool-integrated sensors are spared. Should be a pollution 28 can not be removed, a warning signal can be output and the machine sequence can be interrupted. Thus, the degree of process security can be achieved that requires a fully automated process.

If the cleaning is not done fully automatically, but by a worker, then the visualization of the pollution can serve as orientation for the soiling, especially of dirt 28 in the form of residues that are difficult to detect by the human eye, which makes manual cleaning more efficient and faster.

Furthermore, it can be provided that both the pollution detection used at least one measuring device 3 , as well as the cleaning agent used for cleaning tools are formed on a transfer head and thus the detection and cleaning process can be done directly in succession or at the same time. This can be realized in such a way that the detection method is used downstream in order to check the success of the cleaning step. It is also conceivable to use the measuring means before cleaning, so that in this case there is also the option of cleaning only those areas where contamination has previously been detected.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013109858 A1 [0008]
• DE 102013109859 A1 [0009]
• DE 3837257 A1 [0010]
• EP 1301286 B1 [0012]

Claims (17)

Device for detecting soiling of a molding tool used in forming cycles ( 2 ) for producing a plastic component, with - at least one measuring device ( 3 ) for detecting physical properties of the molding tool that have been changed by the contamination after a molding cycle ( 2 ) and / or a surface ( 25 ) of the molding tool ( 2 ) and - one with the at least one measuring device ( 3 ) connected evaluation unit ( 4 ), which is designed to receive measured values of the at least one measuring device ( 3 ) and / or contamination data generated from the measured values via an interface ( 5 ). Device according to claim 1, characterized by a movement device ( 6 ), which is adapted to the at least one measuring device ( 3 ) after a forming cycle to move and arrange so that a potentially soiled area of the mold ( 2 ) of at least one measuring device ( 3 ) is detectable. Apparatus according to claim 1 or 2, characterized in that the at least one measuring device ( 3 ) is designed to carry out an inductive, resistive, magnetic and / or capacitive detection method. Device according to one of claims 1 to 3, characterized in that the at least one measuring device ( 3 ) via a sliding contact ( 7 ), a magnet ( 37 ), a measuring coil ( 38 ) and / or a Hall sensor ( 39 ). Apparatus according to claim 4, characterized in that the sliding contact ( 7 ) is suspended. Device according to one of claims 1 to 5, characterized in that at least two measuring devices ( 3 ) are provided, which are adapted to dirt at different points of the forming tool ( 2 ) to detect. Apparatus according to claim 6, characterized in that the at least two measuring devices ( 3 ) are arranged substantially in a line or a surface. Device according to one of claims 1 to 7, characterized in that a cleaning device ( 8th ) is provided, which is adapted to the mold ( 2 ) and that the device is designed to read the measured values and / or the contamination data via the interface ( 5 ) to the cleaning device ( 8th ). Device according to one of claims 1 to 8, characterized in that the device via an applicator device ( 9 ), which is adapted to a release agent on the mold ( 2 ) apply. Device according to one of claims 1 to 9, characterized in that the interface ( 5 ) comprises a visualization device - in particular a screen - by means of which the detected pollution can be visualized for a human. Device according to one of claims 1 to 10, characterized in that the device is integrated in a cleaning device for cleaning the mold. Shaping machine with a device according to one of claims 1 to 11. Method for detecting soiling of a molding tool used in forming cycles ( 2 ) for producing a plastic component, wherein - contamination after a molding cycle by means of at least one measuring device ( 3 ) for the detection of pollution-related physical properties of the mold ( 2 ) and / or a surface ( 25 ) of the molding tool ( 2 ) and measuring values of the at least one measuring device and / or contamination data created from the measured values are output. Method according to claim 13, characterized in that the at least one measuring device ( 3 ) is moved and arranged after the molding cycle so that a potentially soiled area of the mold ( 2 ) of at least one measuring device ( 3 ) can be detected. A method according to claim 13 or 14, characterized in that contaminated areas of the mold ( 2 ) - preferably automated - to be cleaned. Method according to one of claims 13 to 15, characterized in that at least one cleaning of the mold ( 2 ), wherein the at least one cleaning before, during and / or after the detection of the physical properties of the mold changed by the soiling ( 2 ) be performed. Plastic molding process, wherein in molding cycles plastic components - preferably by means of a reactive shaping process -, characterized in that after a molding cycle, a method according to any one of claims 13 to 16 is performed.

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