AT521584A1 - Plasticizing unit for a molding machine - Google Patents

Abstract

Plasticizing unit for a molding machine comprising at least one plasticizing cylinder (2) and at least one plasticizing screw (3) arranged in the plasticizing cylinder (2), at least one ultrasound device (4) having at least one transmitting unit (4a) for transmitting and at least one receiving unit (4b) for receiving ultrasound is provided, which at least one ultrasound device (4) is or can be connected to an evaluation unit (5), the at least one transmission unit (4a) being arranged on the at least one plasticizing cylinder (2) and / or having a sound-conducting connection to the at least one a plasticizing cylinder (2) is connected and / or integrated in the at least one plasticizing cylinder (2) and the at least one receiving unit (4b) is arranged on the at least one plasticizing cylinder (2) and / or with a sound-conducting connection to the at least one plasticizing cylinder (2 ) connected and / or in the weni at least one plasticizing cylinder (2) is integrated and the evaluation unit (5) is designed to measure, based on a measurement of the at least one ultrasound device (4), an existence and / or a geometry and / or a position of the at least one plasticizing screw (3) - in particular to determine an eccentricity of the at least one plasticizing screw (3) in the at least one plasticizing cylinder (2) and to output a message based on the measurement.

Description

The present invention relates to a plasticizing unit for a

Molding machine with the features of the preamble of claim 1, a

Molding machine with such a plasticizing unit and a method for

Check at least one plasticizing unit.

Molding machines can be understood to mean injection molding machines, injection presses, presses and the like.

Plasticizing units for molding machines known in the prior art have a plasticizing cylinder in which a plasticizing screw is arranged. The plasticizing screw usually has a web that extends in a thread-like manner along a circumference of the plasticizing screw.

Usually, the plasticizing screw, which is arranged in the plasticizing cylinder, is supported on one side by a drive or a drive unit and can be driven in rotation. On the other hand, in conventional embodiments, the plasticizing cylinder has the injection side. The injection nozzle of the plasticizing cylinder is arranged on this side, as a result of which a plasticized material can be discharged from the plasticizing unit.

The plastification takes place in that a material to be plasticized is subjected to pressure and shear through the plasticizing screw. Due to the high friction that occurs between the plasticizing screw and the material to be plasticized, the material to be plasticized is plasticized by the thermal energy that occurs. An additional energy source can be provided to apply thermal energy for plasticizing, for example a heating coil on or in the plasticizing cylinder. The pressure that occurs in the front area of the plasticizing screw (in the area of the injection nozzle) during plasticization is referred to as back pressure.

Since the plasticizing screw generally has a slightly smaller outer diameter than the inner diameter of the plasticizing cylinder in which the / 34

Plasticizing screw is arranged, the plasticizing screw has a certain

Degree of freedom of movement.

The plasticizing screw is usually stored in the plasticizing cylinder by the drive arranged on one side. The effect of gravity on the plasticizing screw can be deflected. During the plasticizing, the pressure prevailing in the plasticizing cylinder counteracts the deflection of the plasticizing screw along the screw geometry. Ideally, the plasticizing screw aligns itself through this pressure.

However, it is also known that the plasticizing screw can perform wobbling movements (also referred to as precession movements) under internal pressure conditions. These can go so far that contact between the plasticizing screw and the plasticizing cylinder can occur. This is of course to be avoided, since this significantly increases the wear of the plasticizing screw, which is already high.

Consequently, the prior art attempts to align the plasticizing screw as coaxially as possible during operation in the plasticizing cylinder, so that there is a constant distance over the circumference between the plasticizing screw and the plasticizing cylinder. However, in certain cases this turns out to be no easy task. It is known to change the pressure acting on the plasticizing screw by varying process parameters in order to align the plasticizing screw coaxially, because the higher the pressure acting on the plasticizing screw, the safer the coaxial alignment of the plasticizing screw in the plasticizing cylinder. However, due to the process parameters of a production cycle that have to be observed, it is not always possible to achieve the desired pressure conditions.

The facts presented here, however, all take place inside the plasticizing cylinder, which for obvious reasons is not accessible during operation.

/ 34

So it would be desirable to have a possibility of a wobble (or also

Precession) of the plasticizing screw, wear of the plasticizing screw and / or the plasticizing cylinder, contacting between the plasticizing screw and plasticizing cylinder and / or similar circumstances of the operation.

The object of the invention is therefore to provide a plasticizing unit and a method by means of which the plasticizing screw is accessible for measurement purposes during operation and with the least possible impairment of the manufacturing process.

With regard to the plasticizing unit for a molding machine, this object is achieved by the features of claim 1. This is done by providing at least one ultrasound device with at least one transmitting unit for transmitting and at least one receiving unit for receiving ultrasound, which at least one ultrasound device is or can be connected to an evaluation unit, wherein

- The at least one transmission unit is connected to the at least one plasticizing cylinder and / or with a sound-conducting connection to the at least one plasticizing cylinder and / or is integrated in the at least one plasticizing cylinder and

- The at least one receiving unit is connected to the at least one plasticizing cylinder and / or with a sound-conducting connection to the at least one plasticizing cylinder and / or is integrated in the at least one plasticizing cylinder and

- The evaluation unit is designed to determine, based on a measurement of the at least one ultrasound device, an existence and / or a geometry and / or a position of the at least one plasticizing screw, in particular an eccentricity of the at least one plasticizing screw in the at least one plasticizing cylinder and on the basis of the Measurement to output a message.

With regard to the method, the stated object is achieved by the features of claim 25, by means of ultrasound a presence and / or a /

Position of at least one plasticizing screw in at least one plasticizing cylinder is determined.

It should be noted that the at least one ultrasound device can be designed as an integral transmitter or receiver. Alternatively, the at least one ultrasound device can be designed in several parts, i. that is, it has at least one transmitting unit and - separately therefrom - at least one receiving unit. However, it can preferably be provided that the at least one transmitting unit and the at least one receiving unit are formed by the same components for fulfilling a transmitting function and a receiving function.

For example, when using a piezo element (e.g. a piezo speaker), it can be provided that the piezo element is excited to oscillate by reversing the piezo effect, which leads to an ultrasound emission. Such a piezo element can of course also be used as a receiving unit.

By arranging at least one transmitter unit on the at least one plasticizing cylinder and / or in the at least one plasticizing cylinder and / or by virtue of the fact that the at least one transmitter unit is connected via a sound-conducting connection to the at least one plasticizing cylinder and a receiving unit on the at least one plasticizing cylinder and / or in the at least one plasticizing cylinder and / or by the fact that the at least one receiving unit is connected to the at least one plasticizing cylinder via a sound-conducting connection, the transmission and reception of the at least one ultrasonic signal can provide very precise information about this, whether there is a plasticizing screw in the at least one plasticizing cylinder or what geometry or position the plasticizing screw has / occupies in the at least one plasticizing cylinder.

The eccentricity of the plasticizing screw can be understood to mean the distance of the central axis of the plasticizing screw from a central axis of the plasticizing cylinder - possibly at a certain axial position.

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It is therefore also entirely conceivable that, for example, the transmitting unit is integrated in the at least one plasticizing cylinder and the receiving unit is connected to the at least one plasticizing cylinder by a sound-conducting connection.

Measuring signals, which are measured by the ultrasound device, in particular by the receiving unit, and fed to the evaluation unit, can be subjected to preprocessing in the communications technology sense before being transmitted to the evaluation unit. Such processing can include, for example, analog-to-digital conversion of the signals and / or the use of various filters.

Advantageous embodiments of the invention are defined in the dependent claims.

It can preferably be provided that the at least one ultrasound device is designed to carry out a transit time measurement. This represents a simple way of measuring the plasticizing screw. Of course, it is also conceivable to use interferometric measurements or measurements due to diffraction effects.

Within the scope of the invention, a measurement can be understood to mean that the transmitter unit emits an ultrasonic signal at least once, the reflected, diffracted or otherwise changed signal from the interaction with the plasticizing screw is detected by the receiver unit. With pulsed transmission of the signals, which can be advantageous in connection with transit time measurements, the ultrasound pulses emitted by the transmission unit can be transmitted very often in a short time. As a result, several thousand measurements (and more) can be carried out per second.

The continuous transmission of the ultrasonic signals by the transmitter unit is also conceivable, e.g. in connection with interferometric measurements.

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Furthermore, it can preferably be provided that the plasticizing unit is designed to vary at least one process parameter based on the measurement of the at least one ultrasound device. Such a process parameter to be varied can, for example, be a process parameter which entails an increase in the pressure conditions in the plasticizing cylinder and thus an increase in the effective pressure along a circumference of the plasticizing screw. If, for example, only one ultrasound device is provided, it can be ensured that the plasticizing screw is arranged as coaxially as possible in the plasticizing cylinder during the measurement, in order to obtain a result when measuring, for example, a distance between the plasticizing screw and plasticizing cylinder, which is not due to an eccentricity of the plasticizing screw is falsified in the plasticizing cylinder.

It can be provided that the evaluation unit is integrated in the at least one ultrasound device. However, exemplary embodiments are also conceivable in which the evaluation unit is designed by a separate component and the at least one ultrasound device is or can be connected to the evaluation unit.

For example, it can be provided that the function of the evaluation unit is carried out by a central control and regulating unit of a shaping machine. However, it is also possible that the at least one ultrasound device can be connected to an evaluation unit via a LAN, WLAN and / or remote data transmission connection (e.g. Internet).

It can be provided that at least two ultrasound devices are provided, at least two transmitter units and at least two receiver units being arranged on the at least one plasticizing cylinder along a circumference of the at least one plasticizing cylinder and / or connected to the at least one plasticizing cylinder via a sound-conducting connection and / or in the at least one plasticizing cylinder are integrated - preferably axially to one another and / or within a radial cross section through the at least one plasticizing cylinder. For example, when / 34 is provided, at least two ultrasound devices along a circumference of the at least one plasticizing cylinder within a radial cross section through the at least one plasticizing cylinder can make it possible to determine an exact position of the plasticizing screw in the at least one plasticizing cylinder. An interaction between the at least two ultrasound units is also conceivable, so that ultrasound signals emitted by one ultrasound device are received by the other ultrasound device.

Furthermore, it can be provided that the evaluation unit is designed to determine a distance between an inner surface of the at least one plasticizing cylinder and the at least one plasticizing screw arranged therein. For example, a distance between a web of a plasticizing screw and an inner surface of the at least one plasticizing cylinder or the distance between the inner surface of the at least one plasticizing cylinder and the groove base of the at least one plasticizing screw can be determined. It can particularly preferably be provided that the evaluation unit is designed to determine wear by the determined distance between the inner surface of the at least one plasticizing cylinder and the at least one plasticizing screw arranged therein. For example, in the case of a growing distance, it can be concluded that wear of the at least one plasticizing screw and / or of the at least one plasticizing cylinder has occurred. Furthermore, it can be provided that the evaluation unit is designed to determine the wear of the at least one plasticizing screw and / or the inner surface of the at least one plasticizing cylinder.

It can also preferably be provided that the evaluation unit is designed to determine a position of a web of the at least one plasticizing screw on the basis of the determined distance between the inner surface of the at least one plasticizing cylinder and the at least one plasticizing screw arranged therein.

Furthermore, it can be provided that the evaluation unit is designed to determine a current position of the at least one plasticizing screw by means of the determined distance between the inner surface of the at least one plasticizing cylinder and the at least one plasticizing screw arranged therein. In particular, the position of the web can be taken into account. It can preferably be provided that the evaluation unit is designed to determine the position of a central axis of the at least one plasticizing screw in relation to a central axis of the at least one plasticizing cylinder.

It can be provided that the evaluation unit is designed to determine a contact point between the at least one plasticizing screw and an inner surface of the at least one plasticizing cylinder. In one exemplary embodiment, it can be provided that when a certain distance between the inner surface of the at least one plasticizing cylinder and the plasticizing screw is determined, the evaluation unit can conclude that the at least one plasticizing screw on the inner surface of the at least one plasticizing cylinder can determine the at least one plasticizing cylinder contacted. Warnings can then be issued or (automatic) countermeasures taken to prevent contact.

It can particularly preferably be provided that the evaluation unit is designed to determine a position and / or a movement of the at least one plasticizing screw from separate measurements of the at least one ultrasound device. It can be provided that two separate measurements

- are carried out by the same ultrasound device at different times and / or

- Be carried out by at least two ultrasound devices.

The evaluation unit can be designed to determine a rotational movement - preferably a rotational speed of the at least one plasticizing screw - from separate measurements. For example, it can be provided that the evaluation unit detects a movement of a web of the at least one plasticizing screw by means of the two separate measurements and / 34 concludes a rotational speed by means of the movement of a web with the aid of the time that is available between the two separate measurements . Generally speaking, such measurements can also be used to infer the state of motion of the plasticizing screw. This state of motion can be expressed by kinematic parameters, of which the speed of rotation is an example.

Instead of the web, wear marks that occur, for example, on the outer surfaces of the plasticizing screw can also be used in this way to find out the state of movement of the plasticizing screw.

It can also be provided that the evaluation unit is designed to determine at least part of a screw geometry of the at least one plasticizing screw from separate measurements. Thus, in a preferred exemplary embodiment, the evaluation unit can be designed such that it can use the measurement signals of the at least one ultrasound device to infer a screw geometry and / or type of screw.

It is preferably provided that the evaluation unit is designed to determine a movement of a central axis of the at least one plasticizing screw from separate measurements - preferably with respect to a central axis of the at least one plasticizing cylinder, particularly preferably a precession movement or eccentricity of the at least one plasticizing screw.

It can particularly preferably be provided that the evaluation unit and / or a central control or regulating unit of the shaping machine is designed to output an alarm and / or to change a control signal for the plasticizing unit if an actual variable determined by the evaluation unit exceeds a predefinable limit value and / or falls below. The actual size should be referred to one of the sizes already mentioned, such as the distance between the inner surface of the at least one plasticizing cylinder and at least one plasticizing screw and / or the wear and / or the presence of a contact point between the plasticizing cylinder and plasticizing screw and / or a position of the Central axis of the at least one / 34

Plasticizing screw and / or a movement of the at least one

Plasticizing screw and / or a movement of the central axis of the at least one

Plasticizing screw with respect to the central axis of the at least one

Plasticizing cylinder and / or the like.

For example, it can be provided that the control signal to be changed relates to a process variable, a change in the process variable resulting in a change in the dynamic pressure in the at least one plasticizing cylinder. In this exemplary embodiment, the position of the at least one plasticizing screw in at least one plasticizing cylinder can thus be changed by adjusting the dynamic pressure. Other process variables that could be varied, for example, to change the position of the at least one plasticizing screw in at least one plasticizing cylinder, would be the speeds of moving parts in the at least one plasticizing cylinder, plasticizing screw sizes or types, or other process variables that have a direct or indirect influence on the pressure conditions in the at least one plasticizing cylinder .

It can preferably also be provided that the evaluation unit is connected or can be connected to a display device for displaying a current position of the at least one plasticizing screw in the at least one plasticizing cylinder.

It can preferably also be provided that the evaluation unit is connected or can be connected to a display device for displaying wear of the at least one plasticizing screw and / or a precession of the at least one plasticizing screw.

It can be provided that the at least one evaluation unit is designed to output a message to an operator (for example visually or acoustically) or also to a central control or regulating unit of the shaping machine connected to the evaluation unit. It can further be provided that the at least one evaluation unit is connected to a central control or regulating unit of the shaping machine, whereby / 34 it can be provided that the tasks of the at least one evaluating unit are partially taken over by the central control or regulating unit of the shaping machine .

Protection is also sought for a molding machine with a plasticizing unit according to the invention, the evaluation unit preferably being designed to determine the presence and / or position of the at least one plasticizing screw during the operation of the molding machine.

Further advantages and details of the invention emerge from the figures and the associated description of the figures. It shows:

Fig. 1a a first embodiment of a plasticizing unit according to the invention, Fig. 1b Fig. 2a 1 a cross section through the exemplary embodiment of FIG. 1 a, a first measurement of the ultrasound device from the exemplary embodiment of FIG. 1 a, Fig. 2b 2 shows a diagram which represents the results of the measurement from FIG. 2a, Fig. 3a another measurement of the ultrasound device from the Embodiment of Fig. 1a Fig. 3b 3 shows a diagram which represents the results of the measurement from FIG. 3a, Fig. 4a another embodiment of a plasticizing unit according to the invention with two ultrasound devices, Fig. 4b a diagram showing the results of the measurement of the first 4a and Fig. 4c a diagram illustrating the results of the measurement of the second ultrasound device from FIG. 3a.

Fig. 1a shows a first embodiment of an inventive

Plasticizing unit 1 for a molding machine, a plasticizing screw / 34 being arranged in the plasticizing cylinder 2. The plasticizing screw 3 is designed to execute a rotational movement in the plasticizing cylinder 2, as indicated by the arrow. The plasticizing screw 3 has a web 10 which extends in a thread-like manner on the periphery of the plasticizing screw 3. Furthermore, an ultrasound device 4 is provided on the plasticizing cylinder 2, which is connected to an evaluation unit 5 by a signal-conducting connection 11.

In this exemplary embodiment, the transmitting unit 4a and the receiving unit 4b are made by the same component (shown here as an ultrasound device 4).

Optionally, a separate data processing device can be provided between the receiving unit 4b and the evaluation unit 5, by means of which signals of the ultrasound device 4 - in particular the receiving unit 4b - can be processed for the evaluation unit 5. Such processing can include analog-to-digital conversion of the signals and the use of various filters, that is to say generally preprocessing in the communications technology sense.

The plasticizing screw 3 has a central axis 9 and the plasticizing cylinder 2 has a central axis 8. This clearly shows that the central axis 8 of the plasticizing cylinder 2 and the central axis 9 of the plasticizing screw 3 are at a distance from one another, as a result of which the plasticizing screw 3 is eccentric to the plasticizing cylinder 2.

Fig. 1b shows a cross section through the embodiment of Fig. 1a, it being easy to see how the web 10 extends thread-like along the circumference of the plasticizing screw 3 in the axial direction. Furthermore, it can be seen here that there is a distance 7 between the plasticizing screw 3 and the plasticizing cylinder 2.

There are different pressure ratios along the circumference of the plasticizing screw 3 due to an asymmetrical cross section of the plasticizing screw 3 (through the web 10 which extends in a thread-like manner on the circumference of the plasticizing screw 3). In other words: For a developed plasticizing screw 3, the process settings result in / 34

Plasticizing unit 1 is a pressure profile over the length of the development of the plasticizing screw 3, the pressure profile changing over the length of the development. This pressure profile means that the pressure in the cross section of the plasticizing screw 3 is not equally distributed. Consequently, this leads to a reaction force in the radial direction on the plasticizing screw 3, which leads to a precession ("egg") of the plasticizing screw 3 about a central axis 8 of the plasticizing cylinder 2.

The plasticizing screw 3 is not infinitely stiff due to its mass load and reacts with a deflection due to gravity. This deflection in turn results in a shift of the central axis 9 of the plasticizing screw 3 in comparison to the central axis 8 of the plasticizing cylinder 2, which can lead to or increase a precession during rotation.

Due to the rotation of the plasticizing screw 3, the friction of the plasticizing screw 3 on an inner surface 6 of the plasticizing cylinder 2 (in this case a so-called stick-slip effect - or so-called stick-slip effect occurs) results in an uneven force distribution in the tangential direction, so that Plasticizing screw 3 tends to or may increase precession as soon as there is contact between plasticizing screw 3 on an inner surface 6 of the plasticizing cylinder 2.

FIG. 2a shows a first measurement of the ultrasound device 4 from the embodiment of FIG. 1a, the ultrasound device 4 being designed both as a transmitter unit 4a and as a receiver unit 4b. The ultrasound device 4 emits an ultrasound signal 12. The emitted ultrasound signal 12 is reflected by the inner surface 6 of the plasticizing cylinder 2, the ultrasound device 4 reflecting the reflected ultrasound signal

12.1 is received. A thickness of the plasticizing cylinder 2 can thus be determined by this reflected ultrasound signal 12.1.

The ultrasound signal 12 emitted by the ultrasound device 4 is further reflected by the surface of the plasticizing screw 3, the reflected ultrasound signal 12.2 being received by the ultrasound device 4.

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This ultrasonic signal 12.2 provides information about the distance between the surface of the plasticizing screw 3 and the ultrasonic device 4.

The ultrasound device 4 can now forward the received ultrasound signals 12.1, 12.2 to the evaluation unit 5 via the signal-conducting connection 11, the evaluation unit 5 being able to determine a distance 7 between the inner surface 6 of the plasticizing cylinder 2 and the plasticizing screw 3 by the difference. It can be provided that a geometric dimension of the plasticizing screw 3 is stored in the evaluation unit 5, wherein the evaluation unit 5 can be able to determine a position of the plasticizing screw 3 in the plasticizing cylinder 2 based on the determined distance 7 and thereby the deviation of one To calculate the central axis 9 of the plasticizing screw 3 to a central axis 8 of the plasticizing cylinder 2, which makes it possible to reduce this deviation of the central axis 8 from the central axis 9 by changing a process parameter (for example the dynamic pressure).

2b shows a diagram which shows the received ultrasound signals 12.1, 12.2 of the ultrasound device 4 along an abscissa t represented as time. The ordinate is to be understood as the intensity X of the received ultrasound signals. Another ultrasound signal 12.3 can be seen. This ultrasound signal 12.3 results from an ultrasound signal 12 emitted by the ultrasound unit 4, which was reflected by the surface of the plasticizing screw 3, passed back through the inner surface 6 of the plasticizing cylinder 2 to the plasticizing screw 3 and finally back from the surface of the plasticizing screw 3 reaches the ultrasound device 4. Even if this ultrasound signal 12.3 already lost intensity X due to its increased distance, the ultrasound signal 12.3 still provides information about a distance between the inner surface 6 of the plasticizing cylinder 2 and the surface of the plasticizing screw 3. For example, this ultrasound signal 12.3 makes it possible because of of an emitted ultrasound signal from the ultrasound device 4 to receive time-delayed feedback, thereby creating the possibility of detecting a movement of the plasticizing screw 3 by only one emitted ultrasound signal 12.

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Due to the fact that ultrasound signals 12 emitted by the ultrasound device 4 oscillate between a surface of the plasticizing screw 3 and the inner surface 6 of the plasticizing cylinder 2, further ultrasound signals - such as the ultrasound signal 12.3 - can also be expected with a time offset. Even if these further ultrasound signals decrease in their intensity X (until they reach an intensity X which is no longer perceptible by measurement using the ultrasound device 4), these ultrasound signals can be used for the evaluation in the evaluation unit 5 (for example a movement of the plasticizing screw 3).

3a and 3b show a further measurement of the ultrasound device 4 from the previously described embodiment of a plasticizing unit 1 according to the invention, but the measurement of FIG. 3a shows a measurement of the ultrasound device 4 while the web 10 of the plasticizing screw 3 is in the measuring range . Again, it is nice to see how a first ultrasonic signal 12.1 is reflected by the inner surface 6 of the plasticizing cylinder 2 and a second ultrasonic signal 12.2 by the surface (the web 10) of the plasticizing screw 3.

Accordingly, it can be clearly seen in FIG. 3b how the second ultrasound signal

12.2, which was reflected by the web 10 of the plasticizing screw 3, is received much earlier by the ultrasound device 4 than in comparison to FIG. 2b. As a result, the evaluation unit 5 can clearly determine a reduced distance 7, which gives the evaluation unit 5 information about the presence of a web 10 of the plasticizing screw 3.

The rotational speed of the plasticizing screw 3 can be determined by the evaluation unit 5 by measuring the number of webs 10 per minute that “pass” the ultrasound device 4.

If the evaluation unit 5 can determine an oscillation of the values, the measurement can also be used to conclude that the plasticizing screw 3 is precession. By determining a precession of / 34

The plasticizing screw 3 can then be used to optimize the process of the plasticizing unit 1 so that the precession (the "egg") and thus the

Reduction of the lubricating film between the plasticizing screw 3 and the inner surface of the plasticizing cylinder 2 can be reduced.

Depending on the method, the ultrasound device 4 can be designed to emit a pulse or a continuous ultrasound signal. Depending on the distance 7 present, the ultrasound device 4 receives a different (reflected) ultrasound signal 12.1, 12.2, 12.3, which converts the ultrasound device 4 into an electrical signal and transmits it to the evaluation unit 5 via a signal-conducting connection. These received ultrasonic signals 12.1,

12.2, 12.3 differ in the pulse time or also in the form (e.g. the natural frequency) of the signal. Depending on the position of the plasticizing screw 3, a statement can thus be made about the distance 7 between the inner surface 6 of the plasticizing cylinder 2 and the surface of the plasticizing screw 3.

In a further exemplary embodiment it can also be provided that a second ultrasound device 4 is provided, as shown in FIG. 4a. The ultrasound devices 4.1, 4.2 in FIG. 4a are arranged along a circumference of the plasticizing cylinder 2 within a radial cross section on the plasticizing cylinder 2. More specifically, the two ultrasound devices 4.1, 4.2 are offset by 180 ° within a cross section on the circumference of the plasticizing cylinder 2. Again, each of the two ultrasound devices 4.1, 4.2 includes a transmission unit 4a and a reception unit 4b, which are implemented by the same component.

Again, the ultrasound devices 4.1, 4.2.2 emit an ultrasound signal 12, which is reflected back to the ultrasound devices 4.1, 4.2 by different reflection as ultrasound signals 12.1, 12.2.

The received signal of the ultrasound device 4.1 is shown in a table in FIG. 4b and the received signal of the ultrasound device in a table in FIG. 4c

4.2. It can be clearly seen how the ultrasound signals 12.1, which were recorded by the ultrasound devices 4.1.4.2, provide information about the / 34 same distance 7 between the ultrasound devices 4.1.4.2 and the inner surface 6 of the plasticizing cylinder 2, with which it can be concluded that the plasticizing cylinder 2 has the same wall thickness along its circumference. However, the ultrasonic signal 12.2, which was reflected by the surface of the plasticizing screw 3, can be seen with a time delay in FIGS. 4b and 4c, which indicates that the plasticizing screw 3 is positioned eccentrically in the plasticizing cylinder 2.

This time offset of the ultrasound signals 12.2 from FIGS. 4b and 4c (time difference y) enables the evaluation unit 5 to calculate the exact position of the central axis 9 of the plasticizing screw 3 relative to the central axis 8 of the plasticizing cylinder 2.

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Reference symbol list:

Plasticizing unit

Plasticizing cylinder

Plasticizing screw

Ultrasound device

4a transmitter unit

4b receiving unit

4.1 Ultrasound device

4.2 Ultrasound device

Evaluation unit

Inner surface of the plasticizing cylinder

distance

Central axis of the plasticizing cylinder

Central axis of the plasticizing screw

web

Signal-conducting connection

Ultrasound signal

12.1 Ultrasound signal

12.2 Ultrasonic signal

12.3 Ultrasonic signal

X intensity of the received signal t time y time difference

Claims (25)

Claims 1. Plasticizing unit for a molding machine comprising at least one plasticizing cylinder (2) and at least one plasticizing screw (3) arranged in the plasticizing cylinder (2), characterized in that at least one ultrasound device (4) with at least one transmitting unit (4a) for transmitting and at least one receiving unit (4b) is provided for receiving ultrasound, which at least one ultrasound device (4) is or can be connected to an evaluation unit (5), wherein - The at least one transmission unit (4a) is arranged on the at least one plasticizing cylinder (2) and / or is connected to the at least one plasticizing cylinder (2) with a sound-conducting connection and / or is integrated in the at least one plasticizing cylinder (2) and - The at least one receiving unit (4b) is arranged on the at least one plasticizing cylinder (2) and / or is connected to the at least one plasticizing cylinder (2) with a sound-conducting connection and / or is integrated in the at least one plasticizing cylinder (2) and - The evaluation unit (5) is designed, based on a measurement of the at least one ultrasound device (4), to have and / or a geometry and / or a position of the at least one plasticizing screw (3) - in particular an eccentricity of the at least one plasticizing screw (3 ) - to be determined in the at least one plasticizing cylinder (2) and to output a message based on the measurement. 2. Plasticizing unit according to claim 1, characterized in that the at least one ultrasonic device (4) is designed to carry out a transit time measurement. 3. Plasticizing unit according to at least one of the preceding claims, characterized in that the plasticizing unit (1) is designed to vary at least one process parameter during the measurement of the at least one ultrasound device (4). 20/34 83 164 28 / eh 4. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) is integrated in the at least one ultrasound device (4). 5. Plasticizing unit according to at least one of the preceding claims, characterized in that at least two ultrasonic devices (4) are provided, with at least two transmitting units (4a) and at least two receiving units (4b) arranged on the at least one plasticizing cylinder (2) and / or with a sound-conducting connection is connected to the at least one plasticizing cylinder (2) and / or integrated in the at least one plasticizing cylinder (2), preferably axially to one another and / or within a radial cross section through the at least one plasticizing cylinder (2). 6. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) is designed to provide a distance (7) between an inner surface (6) of the at least one plasticizing cylinder (2) and the at least one plasticizing screw arranged therein. 3) to determine. 7. Plasticizing unit according to claim 6, characterized in that the evaluation unit (5) is designed to be determined by the determined distance (7) between the inner surface (6) of the at least one plasticizing cylinder (2) and the at least one plasticizing screw (3) arranged therein ) to determine wear. 8. Plasticizing unit according to claim 7, characterized in that the evaluation unit (5) is designed to determine the wear of the at least one plasticizing screw (3) and / or the inner surface (6) of the at least one plasticizing cylinder (2). 9. Plasticizing unit according to one of claims 6 to 8, characterized in that the evaluation unit (5) is designed, by the determined distance (7) between the inner surface (6) of the at least one 21/34 3 83 164 28 / eh Plasticizing cylinder (2) and the at least one arranged therein Plasticizing screw (3) a current position of the at least one To determine the plasticizing screw (3). 10. Plasticizing unit according to claim 9, characterized in that the evaluation unit (5) is designed to determine the position of a central axis of the at least one plasticizing screw in relation to a central axis of the at least one plasticizing cylinder. 11. Plasticizing unit according to one of claims 6 to 10, characterized in that the evaluation unit (5) is designed, on the basis of the determined distance (7) between the inner surface (6) of the at least one plasticizing cylinder (2) and the at least one arranged therein a plasticizing screw (3) to determine a position of a web (10) of the at least one plasticizing screw (3). 12. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) is designed to determine a contact point between the at least one plasticizing screw (3) and an inner surface (6) of the at least one plasticizing cylinder (2). 13. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) is designed to determine a position and / or a movement of the at least one plasticizing screw (3) from separate measurements of the at least one ultrasonic device (4). 14. Plasticizing unit according to claim 13 and preferably according to claim 5, characterized in that two separate measurements - Are carried out by the same ultrasound device (4) at different times and / or - Are carried out by at least two ultrasound devices (4). 22/34 83 164 28 / eh 15. Plasticizing unit according to claim 13 or 14, characterized in that the evaluation unit (5) is designed to determine a rotational movement, preferably a rotational speed, of the at least one plasticizing screw (3) from separate measurements. 16. Plasticizing unit according to at least one of claims 13 to 15, characterized in that the evaluation unit (5) is designed to determine at least part of a screw geometry of the at least one plasticizing screw (3) from separate measurements. 17. Plasticizing unit according to at least one of claims 13 to 16, characterized in that the evaluation unit (5) is designed to separate a measurement of a movement of a central axis (9) of the at least one plasticizing screw (3), preferably with respect to a central axis ( 8) of the at least one plasticizing cylinder (2), particularly preferably a precession or eccentricity of the at least one plasticizing screw (3). 18. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) and / or a central control or regulating unit of the molding machine is designed to output an alarm and / or to change a control signal for the plasticizing unit (1) , if an actual variable determined by the evaluation unit (5) exceeds and / or falls below a predefinable limit value. 19. Plasticizing unit according to claim 18, characterized in that the control signal to be changed relates to a process variable, a change in the process variable resulting in a change in the dynamic pressure in the at least one plasticizing cylinder (2). 20. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) is connected or connectable to a display device for displaying a current position of the at least one plasticizing screw (3) in the at least one plasticizing cylinder (2). 23/34 83 164 28 / eh 21. Plasticizing unit according to at least one of the preceding claims, characterized in that the evaluation unit (5) is or can be connected to a display device for displaying wear of the at least one plasticizing screw (3). 22. Plasticizing unit according to at least one of the preceding claims, characterized in that the at least one transmitting unit (4a) and the at least one receiving unit (4b) are structurally combined in one unit, preferably the at least one transmitting unit (4a) and the at least one receiving unit ( 4b) are formed by the same components for fulfilling a transmit function and a receive function. 23. Molding machine with a plasticizing unit (1) according to at least one of the preceding claims. 24. Molding machine according to claim 23, characterized in that the evaluation unit (5) is designed to determine the presence and / or position of the at least one plasticizing screw (3) during operation of the molding machine. 25. Method for checking at least one plasticizing unit (1) of a shaping machine, characterized in that the presence and / or position of at least one plasticizing screw (3) in at least one plasticizing cylinder (2) is determined by means of ultrasound.