CN110856969B

CN110856969B - Plasticizing unit for a molding machine

Info

Publication number: CN110856969B
Application number: CN201910781077.XA
Authority: CN
Inventors: G·克拉默; B·普拉赫
Original assignee: Engel Austria GmbH
Current assignee: Engel Austria GmbH
Priority date: 2018-08-24
Filing date: 2019-08-23
Publication date: 2022-08-26
Anticipated expiration: 2039-08-23
Also published as: DE102019122499A1; AT521584B1; AT521584A1; CN110856969A

Abstract

A plasticizing unit for a molding machine, comprising at least one plasticizing cylinder and at least one plasticizing screw arranged in the plasticizing cylinder, at least one ultrasonic device being provided, having at least one transmitting unit for transmitting ultrasonic waves and at least one receiving unit for receiving ultrasonic waves, the at least one ultrasonic device being connectable to an evaluation unit, the at least one transmitting unit being arranged on the at least one plasticizing cylinder and/or being connected to the at least one plasticizing cylinder via a sound-transmitting connection and/or being integrated in the at least one plasticizing cylinder, the at least one receiving unit being arranged on the at least one plasticizing cylinder and/or being connected to the at least one plasticizing cylinder via a sound-transmitting connection and/or being integrated in the at least one plasticizing cylinder, the evaluation unit being configured to determine the presence and/or the geometry and/or the shape of the at least one plasticizing screw in the at least one plasticizing cylinder on the basis of measurements made by the at least one ultrasonic device Or location and outputs a report based on the measurements.

Description

Plasticizing unit for a molding machine

Technical Field

The invention relates to a plasticizing unit for a molding machine, to a molding machine having such a plasticizing unit, and to a method for checking at least one plasticizing unit.

Background

The term molding machine is understood here to mean injection molding machines, presses and the like.

A plasticizing unit commonly used in the prior art for molding machines has a plasticizing cylinder in which a plasticizing screw is arranged. In this case, the plasticizing screw usually has a web which extends in a screw-like manner along the circumference of the plasticizing screw.

In general, the plasticizing screw, which is arranged in the plasticizing cylinder, is supported on one side thereof by a drive device or drive unit and can be driven in rotation. On the other side, the plasticizing cylinder has an injection side in the usual embodiment. On this side, an injection nozzle of the plasticizing cylinder is arranged, by means of which plasticized material can be discharged from the plasticizing unit.

Here, the plasticization is performed by: the material to be plasticized is loaded by the plasticizing screw by means of pressure and shear forces. By means of the high friction generated between the plasticizing screw and the material to be plasticized, the material to be plasticized is plasticized by the heat energy which occurs. In order to apply the thermal energy for the plasticizing, an additional energy source can be provided, for example a heating screw on or in the plasticizing cylinder. The pressure occurring during the plastification in the front region of the plastifying screw (in the region of the injection nozzle) is referred to as the stagnation pressure.

Because the plasticizing screw generally has an outer diameter that is slightly smaller than the inner diameter of the plasticizing cylinder in which it is disposed, the plasticizing screw has a degree of freedom of movement.

The plasticizing screw is usually supported in the plasticizing cylinder by a drive arranged on one side. The plasticizing screw can be deflected due to the effect of gravity on the plasticizing screw. During the plasticizing process, the pressure prevailing in the plasticizing cylinder counteracts the deflection of the plasticizing screw along the screw geometry. The plasticizing screw is thus oriented in an optimized case by means of the pressure.

However, it is also known that the plasticizing screw can execute an oscillating movement (also referred to as a precession movement) under internal pressure conditions. The oscillating movement can be carried out to such an extent that contact between the plasticizing screw and the plasticizing cylinder can occur. This is to be avoided, since it significantly increases the wear of the plasticizing screw which is otherwise high.

The prior art therefore seeks to orient the plasticizing screw as coaxially as possible in the plasticizing cylinder during operation, so that a constant distance is produced between the plasticizing screw and the plasticizing cylinder over the circumference. However, this has not proven to be a simple task in some cases. It is known to vary the pressure acting on the plasticizing screw by varying the process parameters in order to orient the plasticizing screw coaxially, since the higher the pressure acting on the plasticizing screw, the more reliable the coaxial orientation of the plasticizing screw in the plasticizing cylinder. However, the desired pressure conditions cannot always be achieved during operation due to the production cycle process parameters to be observed.

The fact shown here, however, is entirely carried out inside the plasticizing cylinder, which for obvious reasons is not accessible during operation.

Therefore, the following possibilities are desirable and can be identified: the oscillating movement (or precession) of the plasticizing screw, wear of the plasticizing screw and/or of the plasticizing cylinder, contact between the plasticizing screw and the plasticizing cylinder, and/or similar operating conditions.

Disclosure of Invention

The object of the present invention is therefore to provide a plasticizing unit and a method with which the plasticizing screw is accessible in terms of measurement technology during operation and with as little damage as possible to the manufacturing process.

With regard to the plasticizing unit for the molding machine, this is achieved by: at least one ultrasonic device is provided, which has at least one transmitting unit for transmitting ultrasonic waves and at least one receiving unit for receiving ultrasonic waves, said at least one ultrasonic device being connected or connectable to the evaluation unit, wherein

The at least one sending unit is connected to and/or integrated in at least one plasticizing cylinder on and/or with an acoustic connection, and

the at least one receiving unit is connected to and/or integrated in the at least one plasticizing cylinder on and/or via an acoustic connection, and

the evaluation unit is configured to determine the presence and/or geometry and/or position of the at least one plasticizing screw in the at least one plasticizing cylinder, in particular the eccentricity of the at least one plasticizing cylinder, based on the measurements of the at least one ultrasonic device and to output a report based on the measurements.

In this case, the method consists in determining the presence and/or position of at least one plasticizing screw in at least one plasticizing cylinder by means of ultrasound.

It is to be noted that the at least one ultrasonic device may be configured as an integrated transmitter or receiver. Alternatively, the at least one ultrasonic device can be designed in multiple parts, i.e. it has at least one transmitting unit and at least one receiving unit separate from the transmitting unit. However, it can be provided that the at least one transmitting unit and the at least one receiving unit are formed by the same component for fulfilling the transmitting function and the receiving function.

Thus, for example, when using a piezoelectric element (for example a piezoelectric loudspeaker), it can be provided that the piezoelectric element is excited by reversal of the piezoelectric effect to generate vibrations, which result in the transmission of ultrasound waves. Such a piezoelectric element can of course also be used as a receiving unit.

By arranging at least one sending unit on and/or in the at least one plasticizing cylinder and/or by: the at least one transmitting unit is connected to the at least one plasticizing cylinder via an acoustic connection and a receiving unit is arranged on and/or in the at least one plasticizing cylinder and/or by: the at least one receiving unit is connected to the at least one plasticizing cylinder via an acoustic connection, it being possible to deduce in a very precise manner whether the plasticizing screw is completely present in the at least one plasticizing cylinder or what geometry or position the plasticizing screw has/occupies in the at least one plasticizing cylinder by sending and receiving at least one ultrasonic signal.

The eccentricity of the plasticizing screw is understood to mean the distance (optionally at a certain axial position) between the central axis of the plasticizing screw and the central axis of the plasticizing cylinder.

It is therefore also fully conceivable, for example, for the transmitting unit to be integrated in the at least one plasticizing cylinder and for the receiving unit to be connected to the at least one plasticizing cylinder via an acoustic connection.

The measurement signals measured by the ultrasound device, in particular by the receiving unit, and fed to the evaluation unit can be preprocessed in the sense of communication technology before being transmitted to the evaluation unit. Such processing may include, for example, analog-to-digital conversion of the signal and/or use of different filters.

Preferably, it can be provided that the at least one ultrasonic device is designed to carry out a run-time measurement (laufzeitmesung). This is a simple way of measuring the plasticizing screw.

Of course, interference measurements or measurements based on diffraction effects are also contemplated.

In the context of the present invention, a measurement is understood to mean that the transmitting unit emits at least one ultrasonic signal at a time, which is detected by the receiving unit as a reflected, diffracted or otherwise altered signal by interaction with the plasticizing screw. When the signal is pulsed (which may be advantageous in conjunction with the running time measurement), the ultrasonic pulses emitted by the transmitting unit may be emitted very frequently in a short time. Thus, thousands of measurements (and more) per second can be performed.

It is also conceivable to emit the ultrasonic signal continuously by means of the transmitting unit, for example in connection with interference measurements.

Furthermore, it can be provided that the plasticizing unit is configured to change at least one process parameter based on the measurement of the at least one ultrasonic device. Such a process parameter to be changed can be, for example, a process parameter which leads to an increase in the pressure in the plasticizing cylinder and thus to an increase in the pressure acting along the circumference of the plasticizing screw. For example, if only one ultrasonic 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 results which are not distorted by the eccentricity of the plasticizing screw in the plasticizing cylinder when measuring, for example, the distance between the plasticizing screw and the plasticizing cylinder.

Provision can be made for the evaluation unit to be integrated in the at least one ultrasound device. However, embodiments are also conceivable in which the evaluation unit is embodied by a separate component and the at least one ultrasonic device is connected or connectable to the evaluation unit.

Thus, for example, it can be provided that the functions of the evaluation unit are implemented by a central control and regulation unit of the molding machine. However, it is also possible that the at least one ultrasound device can be connected to the evaluation unit via a LAN, a WLAN and/or a data teletransmission connection (e.g. the internet).

It can be provided that at least two ultrasonic devices are provided, wherein at least two transmitting units and at least two receiving units are arranged along the circumference of the at least one plasticizing cylinder on the at least one plasticizing cylinder and/or are connected to the at least one plasticizing cylinder via a sound transmission connection and/or are integrated in the at least one plasticizing cylinder, preferably axially with respect to one another and/or in a radial cross section of the at least one plasticizing cylinder. This can be achieved, for example, if at least two ultrasonic devices are arranged along the circumference of the at least one plasticizing cylinder in a radial cross section through the at least one plasticizing cylinder, the precise position of the plasticizing screw in the at least one plasticizing cylinder being able to be determined. It is also fully conceivable that the at least two ultrasound units interact such that an ultrasound signal emitted by one of the ultrasound devices is received by the other ultrasound device.

Furthermore, it can be provided that the evaluation unit is configured to determine a distance between an inner surface of the at least one plasticizing cylinder and at least one plasticizing screw arranged in the plasticizing cylinder. Thus, for example, the distance between the webs of the plasticizing screw and the inner surface of the at least one plasticizing cylinder can be determined 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. In this case, it can be provided, in a particularly preferred manner, that the evaluation unit is configured to determine the wear by determining a distance between an inner surface of the at least one plasticizing cylinder and at least one plasticizing screw arranged in the plasticizing cylinder. For example, when the distance increases, it can be concluded that the at least one plasticizing screw and/or the at least one plasticizing cylinder are worn. Furthermore, it can be provided that the evaluation unit is configured to determine the wear of the at least one plasticizing screw and/or the wear of the inner surface of the at least one plasticizing cylinder.

Preferably, it can also be provided that the evaluation unit is configured to determine the position of the web of the at least one plasticizing screw on the basis of a determined distance between the inner surface of the at least one plasticizing cylinder and the at least one plasticizing screw arranged in the plasticizing cylinder.

Furthermore, it can be provided that the evaluation unit is configured to determine the instantaneous position of the at least one plasticizing screw by determining a 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 webs can be taken into account here. Preferably, it can be provided that the evaluation unit is configured to determine a position of a center axis of the at least one plasticizing screw relative to a center axis of the at least one plasticizing cylinder.

It can be provided that the evaluation unit is configured 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 embodiment, it can therefore be provided that the evaluation unit can reverse the ejection when a certain distance is determined between the inner surface of the at least one plasticizing cylinder and the plasticizing screw, which contacts the at least one plasticizing cylinder on its inner surface. Then, a warning may be issued or a corresponding measure (automatically) taken to prevent contact.

Particularly preferably, it can be provided that the evaluation unit is configured to determine the position and/or the movement of the at least one plasticizing screw from individual measurements of the at least one ultrasonic device. In this case, two separate measurements can be provided

By the same ultrasonic device at different times, and/or

-by means of at least two ultrasound devices.

The evaluation unit can be configured to determine the rotational movement, preferably the rotational speed, of the at least one plasticizing screw from individual measurements. For example, it can be provided that the evaluation unit determines a movement of a web of the at least one plasticizing screw by means of the two individual measurements and uses the movement of the web to infer the rotational speed by means of the time present between the two individual measurements. In general, the state of motion of the plasticizing screw can also be inferred from such measurements. The motion state may be expressed by a kinematic parameter for which a rotational speed is an example.

Instead of the webs, wear grooves, which occur, for example, on the outer surface of the plasticizing screw, can also be used in this way to determine the state of motion of the plasticizing screw.

It can also be provided that the evaluation unit is configured to determine at least one part of the screw geometry of the at least one plasticizing screw from a separate measurement. In a preferred embodiment, the evaluation unit can therefore be configured to deduce the screw geometry and/or the screw type from the measurement signals of the at least one ultrasonic device.

It is preferably provided that the evaluation unit is configured to determine a movement of the center axis of the at least one plasticizing screw, preferably a movement relative to the center axis of the at least one plasticizing cylinder, particularly preferably a precession movement or an eccentricity of the at least one plasticizing screw, from a separate measurement.

In a particularly preferred manner, it can be provided that the evaluation unit and/or the central control or regulating unit of the molding machine is/are configured to output an alarm and/or to change the control signal for the plasticizing unit if the actual value determined by the evaluation unit exceeds and/or falls below a predefinable limit value. In this case, reference may be made to one of the already mentioned variables as the actual variable, for example the distance between the inner surface of the at least one plasticizing cylinder and the at least one plasticizing screw and/or the wear between the plasticizing cylinder and the plasticizing screw and/or the presence of a contact point and/or the position of the central axis of the at least one plasticizing screw and/or the movement of the central axis of the at least one plasticizing screw relative to the central axis of the at least one plasticizing cylinder and/or the like.

Thus, for example, it can be provided that the control signal to be changed relates to a process variable, wherein a change in this process variable causes a change in the stagnation pressure in the at least one plasticizing cylinder. Thus, in the exemplary embodiment, the position of the at least one plasticizing screw in the at least one plasticizing cylinder may be varied by adjusting the stagnation pressure. The further process variables (which can be varied, for example, to change the position of the at least one plasticizing screw in the at least one plasticizing cylinder) can be the speed of the part moving in the at least one plasticizing cylinder, the size of the plasticizing screw or the type of plasticizing screw or further process variables which have a direct or indirect influence on the pressure conditions in the at least one plasticizing cylinder.

Preferably, it can also be provided that the evaluation unit is connected or connectable to a display device for displaying the instantaneous position of the at least one plasticizing screw in the at least one plasticizing cylinder.

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

It can be provided that the at least one evaluation unit is configured to output a report (e.g. visually or acoustically) to an operator or to a central control or regulating unit of the molding machine, which is connected to the evaluation unit. Furthermore, it can be provided that the at least one evaluation unit is connected to a central control or regulating unit of the molding machine, wherein it can be provided that the task of the at least one evaluation unit is partially assumed by the central control or regulating unit of the molding machine.

Furthermore, a molding machine having a plasticizing unit according to the invention is claimed, wherein the evaluation unit is preferably configured to determine the presence and/or position of the at least one plasticizing screw during operation of the molding machine.

Drawings

Further advantages and details of the invention emerge from the figures and the description of the figures relating thereto.

In the drawings:

figure 1 shows a first embodiment of a plasticizing unit according to the invention,

figure 2a shows a first measurement of the ultrasonic device in the embodiment of figure 1,

fig. 2b shows a graph, which shows the measurement results in fig. 2a,

figure 3a shows another measurement of the ultrasonic device in the embodiment of figure 1,

fig. 3b shows a graph, which shows the measurement results in fig. 3a,

figure 4a shows another embodiment of a plasticizing unit according to the invention having two ultrasonic devices,

fig. 4b shows a diagram, which shows the measurement results of the first ultrasound device in fig. 4a,

fig. 4c shows a diagram which shows the measurement results of the second ultrasonic device in fig. 4 a.

Detailed Description

Fig. 1 shows a first exemplary embodiment of a plasticizing unit 1 for a molding machine according to the invention, in which a plasticizing screw 3 is arranged in a plasticizing cylinder 2. In this case, 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 over the circumference of the plasticizing screw 3. Furthermore, an ultrasonic device 4 is arranged on the plasticizing cylinder 2, which is connected to the evaluation unit 5 via a signal-conducting connection 11.

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

Alternatively, a separate data processing device can be provided between the receiving unit 4b and the evaluation unit 5, by means of which data processing device the signals of the ultrasound device 4 (in particular the receiving unit 4b) for the evaluation unit 5 can be processed. Such processing may include analog-to-digital conversion of the signal and the use of different filters, i.e. preprocessing in general in the sense of communication technology.

The plasticizing screw 3 has a central axis 9 and the plasticizing cylinder 2 has a central axis 8. It is clear from this that the center axis 8 of the plasticizing cylinder 2 and the center axis 9 of the plasticizing screw 3 are at a distance from one another, so that the plasticizing screw 3 is eccentric with respect to the plasticizing cylinder 2.

B in fig. 1 shows a cross section of the exemplary embodiment of a in fig. 1, wherein it can be clearly seen how the webs 10 extend in the axial direction along the circumference of the plasticizing screw 3 in a thread-like manner. Furthermore, it can be seen here that a spacing 7 exists between the plasticizing screw 3 and the plasticizing cylinder 2.

Due to the asymmetrical cross section of the plasticizing screw 3 (through the web 10, which extends in a screw-like manner over the circumference of the plasticizing screw 3), different pressure conditions occur along the circumference of the plasticizing screw 3. In other words: for the extended plasticizing screw 3, due to the process settings of the plasticizing unit 1, a pressure characteristic curve is obtained over the extended length (abbicklung) of the plasticizing screw 3, wherein the pressure characteristic curve varies over the extended length. The pressure characteristic curve results in a pressure which is not distributed uniformly over the cross section of the plasticizing screw 3. This therefore results in a reaction force acting in the radial direction on the plasticizing screw 3, which leads to a precession ("wobble") of the plasticizing screw 3 about the central axis 8 of the plasticizing cylinder 2.

The plasticizing screw 3 is not infinitely rigid due to its mass loading and reacts to the deflection due to gravity. This deflection in turn causes the center axis 9 of the plasticizing screw 3 to move relative to the center axis 8 of the plasticizing cylinder 2, which may lead to a precession during rotation or may intensify this precession.

Due to the rotation of the plasticizing screw 3, the plasticizing screw 3 is easily advanced or can be strengthened as soon as there is contact between the plasticizing screw 3 and the inner surface 6 of the plasticizing cylinder 2, due to the friction of the plasticizing screw 3 on the inner surface 6 of the plasticizing cylinder 2 (in this case, in part, the so-called stick-slip effect, also referred to as stick-slip effect) which produces an uneven force distribution in the tangential direction.

Fig. 2a shows a first measurement of the ultrasonic device 4 in the exemplary embodiment of fig. 1, wherein the ultrasonic device 4 is designed both as a transmitting unit 4a and as a receiving unit 4 b. The ultrasound device 4 here transmits an ultrasound signal 12. The transmitted ultrasonic signal 12 is reflected by the inner surface 6 of the plasticizing cylinder 2, wherein the reflected ultrasonic signal 12.1 is received by the ultrasonic device 4. The thickness of the plasticizing cylinder 2 can thus be determined from the reflected ultrasonic signal 12.1.

The ultrasonic signal 12 transmitted by the ultrasonic device 4 is also reflected by the surface of the plasticizing screw 3, wherein the reflected ultrasonic signal 12.2 is received by the ultrasonic device 4. The ultrasonic signal 12.2 deduces the distance between the surface of the plasticizing screw 3 and the ultrasonic device 4.

The ultrasonic device 4 can now transmit the received ultrasonic signals 12.1, 12.2 further to the evaluation unit 5 via the signal-conducting connection 11, wherein the evaluation unit 5 can determine the distance 7 between the inner surface 6 of the plasticizing cylinder 2 and the plasticizing screw 3 by means of the difference. In this case, it can be provided that the geometric dimensions of the plasticizing screw 3 are stored in the evaluation unit 5, wherein the evaluation unit 5 can determine the position of the plasticizing screw 3 in the plasticizing cylinder 2 on the basis of the determined distance 7 and can calculate the deviation of the center axis 9 of the plasticizing screw 3 from the center axis 8 of the plasticizing cylinder 2, as a result of which it is possible to reduce the deviation of the center axis 8 from the center axis 9 by changing process parameters (e.g., stagnation pressure).

Fig. 2b shows a diagram which represents the received ultrasonic signals 12.1, 12.2 of the ultrasonic device 4 along an abscissa t shown as time. Here, the ordinate indicates the intensity X of the received ultrasonic signal. Another ultrasonic signal 12.3 can be seen. The ultrasonic signal 12.3 is derived from the ultrasonic signal 12 transmitted by the ultrasonic unit 4, which is reflected by the surface of the plasticizing screw 3, is guided back again onto the plasticizing screw 3 by way of the inner surface 6 of the plasticizing cylinder 2 and finally returns from the surface of the plasticizing screw 3 to the ultrasonic device 4. Even if the ultrasonic signal 12.3 has lost the intensity X due to its increased distance, the ultrasonic signal 12.3 always concludes the distance between the inner surface 6 of the plasticizing cylinder 2 and the surface of the plasticizing screw 3. Thus, for example, the ultrasonic signal 12.3 makes it possible to receive a feedback of the time delay based on the transmitted ultrasonic signal of the ultrasonic device 4, thereby making it possible to: the movement of the plasticizing screw 3 is determined by only one transmitted ultrasonic signal 12.

Since the ultrasonic signal 12 sent by the ultrasonic device 4 oscillates between the surface of the plasticizing screw 3 and the inner surface 6 of the plasticizing cylinder 2, other ultrasonic signals having a time delay like the ultrasonic signal 12.3 are also conceivable. Even if the other ultrasonic signals are reduced in their intensity X (until they reach an intensity X which is no longer perceptible in terms of measurement technology by the ultrasonic device 4), these ultrasonic signals can be taken into account for the evaluation in the evaluation unit 5 (for example the movement of the plasticizing screw 3).

Fig. 3a and 3b show a further measurement of the ultrasonic device 4 in the embodiment of the plasticizing unit 1 according to the invention already described above, but in the measurement of fig. 3a the measurement of the ultrasonic device 4 is carried out with the web 10 of the plasticizing screw 3 in the measurement region. It can again be clearly seen how the first ultrasonic signal 12.1 is reflected by the inner surface 6 of the plasticizing cylinder 2 and the second ultrasonic signal 12.2 is reflected by the surface (web 10) of the plasticizing screw 3.

Correspondingly, it can be clearly seen in fig. 3b how the second ultrasonic signal 12.2 reflected by the web 10 of the plasticizing screw 3 is received again by the ultrasonic device 4 earlier in time than in fig. 2 b. The reduced distance 7 can thus be unambiguously determined by the evaluation unit 5, which allows the evaluation unit 5 to conclude that a web 10 of the plasticizing screw 3 is present.

By measuring the number of webs 10 "passing through" the ultrasonic device 4 per minute, the rotational speed of the plasticizing screw 3 can be determined by the evaluation unit 5.

If the oscillation of the values can be determined by the evaluation unit 5, the precession of the plasticizing screw 3 can also be inferred from the measurements. By determining the precession of the plasticizing screw 3, the process of the plasticizing unit 1 can then be optimized with respect to wear, so that the precession ("wobble") and thus the reduction of the lubricating film between the plasticizing screw 3 and the inner surface 6 of the plasticizing cylinder 2 can be reduced.

The ultrasound device 4 may be configured to transmit pulsed or continuous ultrasound signals according to the method. Depending on the distance 7 present, the ultrasonic device 4 receives different (reflected) ultrasonic signals 12.1, 12.2, 12.3, which the ultrasonic device 4 converts into electrical signals and transmits to the evaluation unit 5 via a signal-conducting connection. These received ultrasonic signals 12.1, 12.2, 12.3 differ in terms of pulse time or in terms of the form of the signal (e.g. natural frequency). The distance 7 between the inner surface 6 of the plasticizing cylinder 2 and the surface of the plasticizing screw 3 can thus be described in terms of the position of the plasticizing screw 3.

In a further exemplary embodiment, it can also be provided that a second ultrasonic device 4 is provided, as is shown in fig. 4 a. The ultrasonic devices 4.1, 4.2 of fig. 4a are arranged along the circumference of the plasticizing cylinder 2 in a radial cross section on the plasticizing cylinder 2. More precisely, the two ultrasonic devices 4.1, 4.2 are offset by 180 ° in a cross section at the circumference of the plasticizing cylinder 2. Each of the two ultrasound devices 4.1, 4.2 in turn comprises a transmitting unit 4a and a receiving unit 4b, which are implemented by the same component.

The ultrasonic devices 4.1, 4.2 in turn emit ultrasonic signals 12, which are reflected back to the ultrasonic devices 4.1, 4.2 as ultrasonic signals 12.1, 12.2 by different reflections.

The signals received by the ultrasonic device 4.1 are shown in fig. 4b in the form of a graph and the signals received by the ultrasonic device 4.2 are shown in fig. 4c in the form of a graph. In this case, it is clearly apparent how the ultrasonic signal 12.1 received by the ultrasonic devices 4.1, 4.2 indicates the same distance 7 between the ultrasonic devices 4.1, 4.2 and the inner surface 6 of the plasticizing cylinder 2, and thus the plasticizing cylinder 2 has the same wall thickness in its circumferential direction. However, the ultrasonic signal 12.2 reflected by the surface of the plasticizing screw 3 is offset in time as can be seen in fig. 4b and 4c, which concludes that the plasticizing screw 3 is positioned eccentrically in the plasticizing cylinder 2.

By means of this temporal offset (time difference y) of the ultrasonic signal 12.2 in fig. 4b and 4c, the exact position of the center axis 9 of the plasticizing screw 3 relative to the center axis 8 of the plasticizing cylinder 2 can be calculated by the evaluation unit 5.

List of reference numerals

1 plasticizing unit

2 plasticizing cylinder

3 plasticizing screw

4 ultrasonic device

4a transmitting unit

4b receiving unit

4.1 ultrasonic device

4.2 ultrasonic device

5 analysis processing unit

6 inner surface of plasticizing cylinder

7 space apart

8 axle wire of plasticizing cylinder

9 central axis of plasticizing screw

10 contact piece

11 connector for conducting signals

12 ultrasonic signal

12.1 ultrasonic signals

12.2 ultrasonic signals

12.3 ultrasonic signals

X received signal strength

time t

Difference of y time

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 ultrasonic device (4) is provided, which has at least one transmitting unit (4a) for transmitting ultrasonic waves and at least one receiving unit (4b) for receiving ultrasonic waves, the at least one ultrasonic device (4) being connectable to an evaluation unit (5), wherein

-the at least one sending unit (4a) is arranged on the at least one plasticizing cylinder (2) or is connected to the at least one plasticizing cylinder (2) by means of a sound-transmitting connection 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) or is connected to the at least one plasticizing cylinder (2) by means of a sound-transmitting connection or is integrated in the at least one plasticizing cylinder (2), and

-the analysis processing unit (5) is configured to determine the eccentricity of the at least one plasticizing screw (3) in the at least one plasticizing cylinder (2) based on the measurements of the at least one ultrasonic device (4) and to output a report based on the measurements.

2. Plasticizing unit according to claim 1, characterized in that the at least one ultrasonic device (4) is configured to carry out a running time measurement.

3. Plasticizing unit according to claim 1 or 2, characterized in that the plasticizing unit (1) is configured to change at least one process parameter during the measurement of the at least one ultrasonic device (4).

4. Plasticizing unit according to claim 1 or 2, characterized in that the analysis processing unit (5) is integrated in the at least one ultrasonic device (4).

5. Plasticizing unit according to claim 1 or 2, characterized in that at least two ultrasonic devices (4) are provided, wherein at least two transmitting units (4a) and at least two receiving units (4b) are provided on the at least one plasticizing cylinder (2) or are connected to the at least one plasticizing cylinder (2) by means of a sound-transmitting connection or are integrated in the at least one plasticizing cylinder (2).

6. Plasticizing unit according to claim 5, characterized in that the at least two sending units (4a) and the at least two receiving units (4b) are arranged axially to each other or within a radial cross section of the at least one plasticizing cylinder (2).

7. Plasticizing unit according to claim 1, characterized in that the evaluation unit (5) is configured to determine a spacing (7) between an inner surface (6) of the at least one plasticizing cylinder (2) and the at least one plasticizing screw (3) arranged therein.

8. Plasticizing unit according to claim 7, characterized in that the evaluation unit (5) is configured to determine the wear by means of a determined spacing (7) between the inner surface (6) of the at least one plasticizing cylinder (2) and the at least one plasticizing screw (3) arranged therein.

9. Plasticizing unit according to claim 8, characterized in that the analysis processing unit (5) is configured to determine the wear of the at least one plasticizing screw (3) and/or the wear of the inner surface (6) of the at least one plasticizing cylinder (2).

10. Plasticizing unit according to one of claims 7 to 9, characterized in that the evaluation unit (5) is configured to determine the instantaneous position of the at least one plasticizing screw (3) by means of a determined spacing (7) between the inner surface (6) of the at least one plasticizing cylinder (2) and the at least one plasticizing screw (3) arranged therein.

11. Plasticizing unit according to claim 10, characterized in that the analysis processing unit (5) is configured to determine the position of the central axis of the at least one plasticizing screw relative to the central axis of the at least one plasticizing cylinder.

12. Plasticizing unit according to one of claims 7 to 9, characterized in that the evaluation unit (5) is configured to determine the position of the tab (10) of the at least one plasticizing screw (3) 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 plasticizing screw (3) arranged therein.

13. Plasticizing unit according to claim 1 or 2, characterized in that the analysis processing unit (5) is configured to determine a contact point between the at least one plasticizing screw (3) and the inner surface (6) of the at least one plasticizing cylinder (2).

14. Plasticizing unit according to claim 1 or 2, characterized in that the analysis processing unit (5) is configured to determine the position and/or movement of the at least one plasticizing screw (3) from individual measurements of the at least one ultrasonic device (4).

15. Plasticizing unit according to claim 14, characterized in that two separate measurements

-by the same ultrasonic device (4) at different times, or

-by means of at least two ultrasound devices (4).

16. Plasticizing unit according to claim 14, characterized in that at least two ultrasonic devices (4) are provided, wherein two separate measurements

-by the same ultrasonic device (4) at different times, or

-by means of at least two ultrasound devices (4).

17. Plasticizing unit according to claim 14, characterized in that the analysis processing unit (5) is configured to determine the rotational movement of the at least one plasticizing screw (3) from a separate measurement.

18. Plasticizing unit according to claim 14, characterized in that the analysis processing unit (5) is configured to determine the rotational speed of the at least one plasticizing screw (3) from a separate measurement.

19. Plasticizing unit according to claim 14, characterized in that the analysis processing unit (5) is configured to determine at least a part of the screw geometry of the at least one plasticizing screw (3) from separate measurements.

20. A plasticizing unit according to claim 14, characterised in that the analysis processing unit (5) is configured to determine the movement of the central axis (9) of the at least one plasticizing screw (3) from a separate measurement.

21. Plasticizing unit according to claim 14, characterized in that the evaluation unit (5) is configured to determine the movement of the central axis of the at least one plasticizing screw relative to the central axis (8) of the at least one plasticizing cylinder (2) from separate measurements.

22. Plasticizing unit according to claim 14, characterized in that the analysis processing unit (5) is configured to determine the precession or eccentricity of the at least one plasticizing screw (3) from separate measurements.

23. Plasticizing unit according to claim 1 or 2, characterized in that an evaluation unit (5) of the molding machine and/or a central control or regulating unit is configured to output an alarm and/or to change the control signal for the plasticizing unit (1) if the actual variable determined by the evaluation unit (5) exceeds or falls below a predeterminable limit value.

24. Plasticizing unit according to claim 23, characterized in that the control signal to be changed relates to a process variable, wherein a change of the process variable causes a change of the stagnation pressure in the at least one plasticizing cylinder (2).

25. Plasticizing unit according to claim 1 or 2, characterized in that the evaluation unit (5) is connectable to a display device for displaying the instantaneous position of the at least one plasticizing screw (3) in the at least one plasticizing cylinder (2).

26. Plasticizing unit according to claim 1 or 2, characterized in that the analysis processing unit (5) is connectable with a display device for displaying the wear of the at least one plasticizing screw (3).

27. A plasticizing unit as defined in claim 1 or 2, characterized in that said at least one sending unit (4a) and said at least one receiving unit (4b) are structurally combined into one unit.

28. A plasticizing unit as claimed in claim 27, characterized in that said at least one transmitting unit (4a) and said at least one receiving unit (4b) are constituted by the same member for fulfilling a transmitting function and a receiving function.

29. Moulding machine having a plasticizing unit (1) according to any one of claims 1 to 28.

30. The molding machine according to claim 29, characterized in that the analysis processing unit (5) is configured to determine the presence of the at least one plasticizing screw (3) during operation of the molding machine.

31. The molding machine according to claim 29, characterized in that the analysis processing unit (5) is configured to determine the position of the at least one plasticizing screw (3) during operation of the molding machine.

32. Method for checking at least one plasticizing unit (1) of a molding machine, the plasticizing unit (1) being a plasticizing unit according to any one of claims 1 to 28, characterized in that the eccentricity of at least one plasticizing screw (3) in at least one plasticizing cylinder (2) is determined by means of ultrasound.