AT16801U1 - Plastic molding machine and method for checking such - Google Patents

Abstract

Plastic molding machine with at least one component which is subjected to a force and / or a counterforce opposing the force by at least one drive, characterized in that at least one ultrasonic device (10) with at least one transmitting unit (10.2) for transmitting and at least one receiving unit (10.1) for receiving ultrasound, which ultrasound device (10) is or can be connected to an evaluation unit (7), the at least one transmitting unit (10.2) being arranged on the at least one component and / or connected to the at least one component via a sound-conducting connection and / or is integrated into the at least one component and the at least one receiving unit (10.1) is arranged on the at least one component and / or connected to the at least one component via a sound-conducting connection and / or is integrated into the at least one component and the evaluation unit it (7) is designed to determine, on the basis of a measurement of the at least one ultrasonic device (10), a change in dimension and / or a change in position of the at least one component directly or indirectly and, on the basis of the measurement, to output a message relating to the force itself and / or an effect of the force on the plastic molding machine and / or a molding tool (13) is representative.

Description

description

The present invention relates to a plastic molding machine with the features of the preamble of claim 1 and a method for checking at least one component of a plastic molding machine.

Under plastic molding machines, plastic processing machines, such as injection molding machines, transfer presses and the like, can be understood. In the following, the prior art is described using injection molding machines as an example. Analogous statements apply in general to plastic molding machines.

[0003] Closing units for injection molding machines known in the prior art have at least two mold mounting plates which are suitable for transmitting a closing force to a mold mounted thereon. This closing force is required to keep a mold closed under injection pressure (and the resulting internal mold pressure).

Molds have two or more mold parts which form a cavity in the closed state. This cavity has the geometric dimensions of a component to be molded. When the mold is closed, molding compound is introduced into the mold cavity. The mold is kept closed until the molding compound has essentially hardened. In order to eject the molded part to be produced from the molding tool, the molding tool is opened and the molded part produced is ejected, for example, by means of an ejector unit.

In many cases it is desired to measure the actual closing force, for example for monitoring purposes, independently of the closing force mechanism. Clamping forces that are too low or too high can namely lead to damage to the mold.

Thus, it is known from the prior art to equip generic clamping units for plastic molding machines with measuring sensors so that clamping force sizes can be determined and / or positions of the mold mounting plates, which provide information about a gaping of the mold. Strain gauges (strain gauges) can be used as measuring sensors, whereby a position or force can be deduced from a strain on the strain gauge. Such strain gauges are applied to components of the clamping unit and the mold in order to measure the deformation of these components.

The provision of such measuring devices is usually associated with a high level of effort in terms of production technology, since it is often not trivially possible to arrange such measuring devices at the measuring points. Strain gages must always be arranged in a force flow in order to receive representative measurement signals, whereby they are always exposed to the risk of damage from the application of force. Another disadvantage of using strain gauges is that the dimensional accuracy is not very high.

It is also desirable to be able to determine injection forces which occur during injection in an injection molding machine. For the injection of the plastic in an injection molding machine, the plasticizing screw (which is also used to plasticize the molding compound) is moved in the axial direction in the plasticizing cylinder by, for example, a spindle and a drive unit connected to it, in order to bring the plasticized molding compound from the plasticizing cylinder into the cavity of the molding tool . In order to determine an injection force or an injection pressure, it is common to measure the load applied to the drive unit and to infer an existing resistance (injection force or pressure) based on this load. However, such a procedure only supplies representative values for the actually prevailing pressures and forces to a limited extent, since only a relatively poor accuracy and resolution can be achieved due to the prevailing friction and pressure conditions. In particular, taking into account the friction sets limits for the accuracy.

The same applies to an ejector unit of a plastic injection molding machine. The ejector unit can also be driven in a linear direction by means of a spindle and an associated drive unit

be moved. In this case, too, the desire arises from the state of the art for a measuring method for more reliable and more precise measurement of forces that occur.

The object of the invention is therefore to provide a plastic molding machine and a method with which the plastic molding machine becomes more metrologically accessible during operation and with the least possible impairment of the manufacturing process.

With regard to the plastic molding machine, this object is achieved by the features

of claim 1 solved. This is done by using at least one ultrasonic device with

At least one sending unit for sending and at least one receiving unit for receiving

of ultrasound is provided, which ultrasound device is connected to an evaluation unit

den or is connectable, wherein

the at least one transmission unit is arranged on at least one component and / or is connected to the at least one component via a sound-conducting connection and / or is integrated into the at least one component and

the at least one receiving unit is arranged on the at least one component and / or is connected to the at least one component with a sound-conducting connection and / or is integrated into the at least one component and

the evaluation unit is designed to determine a change in dimension and / or a change in position of the at least one component directly or indirectly on the basis of a measurement of the at least one ultrasonic device and to output a message based on the measurement that relates to the force itself and / or an effect the force on the plastic molding machine and / or a molding tool is representative.

With regard to the method, the set object is achieved by the features of claim 34 by directly or indirectly determining a change in size and / or position of at least one component of the plastic molding machine based on a measurement by means of ultrasound and output a message based on the measurement which is representative of a force and / or an effect of the force on the plastic molding machine and / or on a molding tool.

The invention can be used to detect various forces and / or their effects on the plastic molding machine. Examples of such forces would be an injection force, an ejector force or a closing force applied by a closing unit of the plastics molding machine.

These examples can of course be combined with one another or the invention can be used separately for these examples.

Another advantage of the invention is that a force flow can be measured directly and / or the measuring device can be freely positioned and / or a higher accuracy of the measurement results can be achieved.

In the context of the invention, a direct measurement can be understood to be a measurement of the change in dimension in the direction of the force. An indirect measurement can be understood to be a measurement which allows a conclusion to be drawn about the change in dimension in the direction of the force, for example by inferring a change in dimension from a change in position.

It should be noted that the at least one ultrasonic device can be designed as an integral transmitter or receiver. Alternatively, the at least one ultrasonic device can be designed in several parts. This means that it has at least one transmitter unit and - separately from this - at least one receiver unit. Preferably, however, it can be provided that the at least one transmitting unit and the at least one receiving unit are formed by the same components for carrying out a transmitting function and a receiving function.

For example, when using a piezo element (e.g. piezo loudspeaker) it can be provided that the piezo element is excited to oscillate, which leads to an ultrasound emission. Such a piezo element can by reversing the piezoelectric

can also be used as a receiving unit.

[0019] Counterforces can be, for example, buoyancy forces generated in a mold by internal mold pressure or Newtonian reaction forces.

An advantage of using ultrasound to measure a change in dimension and / or a change in position of the at least one component is that the use of ultrasound enables far more precise resolutions of the measurement compared to measurement methods (for example a measurement using a strain gauge), which are known in the art. A higher resolution of the measurement is understood to mean an increasing measurement accuracy. Furthermore, there is the advantage that the higher resolution also enables, for example, a movement or deformation of the at least one component, a clamping unit, an injection unit or even the entire plastic molding machine, preferably over a period of time, to be determined, with the deformation not only indicating a Allows closing force, but also on other forces acting in the process (such as an injection force resulting from the injection pressure).

As at least one component, any part of the plastic molding machine can be used which is subjected to a force or counterforce by at least one drive of the plastic molding machine.

The force can for example be a closing force.

By arranging at least one transmission unit on the at least one component and / or integrating in the at least one component and / or in that the at least one transmission unit is connected to the at least one component via a sound-conducting connection and a receiving unit is connected to the at least a component is connected and / or is integrated in the at least one component and / or in that at least one receiving unit is connected to the at least one component via a sound-conducting connection, can by sending and receiving the at least one ultrasonic signal in a very precise way and information about a change in position and / or a change in dimension of the at least one component can be provided.

The sound-conducting connection can be implemented, for example, via a metallic contact or a - preferably temperature-resistant - gel. The gel can improve the coupling of ultrasonic signals transmitted for the purpose of measurement.

For the purpose of the measurement, ultrasonic signals transmitted by the ultrasonic device can be transmitted in a modulated manner, in order to facilitate the recognition of the signal during the measurement by detecting the modulation.

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

A change in position can be understood to mean a change in the position of the at least one component relative to another. Such a relative component can be, for example, a frame of the plastics molding machine or also a further component of the plastics molding machine.

Examples of messages that are representative of the force itself and / or an effect of the force on the plastic molding machine and / or the molding tool would be, for example, the output of the values of the specific change in dimension or position change or a change in force or a (closing) Force profile.

[0029] Advantageous embodiments of the invention are defined in the dependent claims.

[0030] It can be provided that the at least one component is a

at least one drive-driven spindle. For example, a recirculating ball screw can also be used here. It can preferably be provided that a change in length and / or a change in cross section of the spindle can be determined by the evaluation unit. Of course, a connection between these two variables (change in length and change in cross section of the spindle) can also be established using Hook’s law. The elastic deformation of the spindle provides direct information about a prevailing force that acts on the spindle.

[0031] It can preferably be provided that the spindle is or can be connected to an ejector unit of the plastic molding machine, whereby the force acting on the spindle can be measured. The evaluation unit can be designed to output a momentarily acting ejector force within the scope of the message on the basis of the specific change in dimension and / or the change in position of the spindle.

[0032] It can further be provided that the at least one component is a component of the injection unit that can be driven by the at least one drive - preferably a plasticizing screw. It can also be provided, for example, that the drivable component of the injection unit is an injection piston (which is used, for example, to inject the plasticized mass into the cavity). It can preferably be provided that a change in length of the drivable component of the injection unit can be determined by the at least one evaluation unit. In the context of such an embodiment, the evaluation unit can be designed to output a momentarily acting injection force within the scope of the message on the basis of the specific change in dimension and / or the change in position of the drivable component of the injection unit.

In an exemplary embodiment it can be provided that the at least one component is at least one injection cylinder (also often called mass cylinder in the prior art), an axial change in length being detectable by the at least one ultrasonic unit. It can thus be provided that the evaluation unit can determine a contact force of the at least one injection cylinder and preferably a force profile on the basis of the axial change in length. Before a plasticized mass is injected into at least one mold cavity of the at least one molding tool, an injection cylinder is brought up to the molding tool or a component connected to the molding tool and is pressed against it with a contact force. This contact pressure is used to ensure that the injection cylinder does not lift off the molding tool or the component connected to the molding tool during injection.

Alternatively or additionally it can be provided that the at least one component is at least part of a piston-cylinder unit. The evaluation unit can be designed to detect a change in length of at least a part of a piston-cylinder unit, wherein a force exerted by the piston-cylinder unit can preferably be determined by the evaluation unit. The piston-cylinder unit can be designed as part of a hydraulic or pneumatic system.

The plastic molding machine preferably has the following: at least two mold clamping plates which are suitable for transmitting a clamping force to a mold mounted thereon and a clamping force mechanism which is designed to apply the clamping force to the at least two mold clamping plates, wherein the at least one component is a component of the closing unit which is exposed to the force caused by the application of the closing force and / or a counterforce opposing the closing force, the message to be output from the evaluation unit representing an effect of the application of the closing force on the closing unit and / or a molding tool.

[0036] It can preferably be provided that the at least one drive is designed as a closing force mechanism of the plastic molding machine.

[0037] It can preferably be provided that the at least one ultrasonic device

is designed to carry out a transit time measurement. This represents a simple way of measuring the plastic molding machine. Of course, it is in principle also conceivable to use interferometric measurements or measurements based on diffraction effects.

In the context of the invention, a measurement can be understood to mean that the transmitting unit transmits at least once an ultrasonic signal whose reflected, diffracted or otherwise changed signal by the interaction with the at least one component is detected by the receiving unit. With pulsed transmission of the signals, which can be advantageous in connection with the transit time measurement, the ultrasonic pulses transmitted by the transmission unit can be transmitted very often in a short time. This means that several thousand measurements (and more) can be carried out per second.

The continuous transmission of ultrasound by the transmitting unit is also conceivable, for. B. in connection with interferometric measurements.

It can be provided that the evaluation unit is integrated into the at least one ultrasonic device. However, designs are also conceivable in which the evaluation unit is designed as 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 or regulating unit of the plastic molding machine. However, it is also possible that the at least one ultrasonic device can be connected to an evaluation unit via a LAN, WLAN and / or other remote data transmission connections (e.g. Internet).

It can be provided that the evaluation unit is designed to generate a momentarily acting closing force and / or a momentarily acting force distribution and / or an existing tool breathing and / or a lifting due to the specific change in dimension and / or the change in position of the at least one component of the molding tool and / or a contact of the molding tool and preferably information about the momentarily acting closing force and / or the momentarily acting force distribution and / or an existing tool breathing and / or the lifting of the molding tool and / or the contact of the molding tool in the context of the message to spend.

It is preferably provided that the evaluation unit is designed to infer a deformation of the at least one component based on the change in dimension and / or the change in position of the at least one component and preferably to output information about the deformation of the at least one component in the context of the message . An example of a deformation is the deformation of a mold mounting plate or a part of a toggle lever mechanism, which is subjected to a bending load when subjected to a clamping force and during injection.

It is particularly preferably provided that the evaluation unit is designed to output the message if a momentarily acting injection force determined by the evaluation unit and / or a momentarily acting ejector force and / or a momentarily acting closing force and / or an existing tool breathing and / or a lifting of the molding tool and / or a contact of the molding tool exceeds and / or falls below a predeterminable limit value. This is an easy way to effectively monitor the plastic molding machine.

For example, it can be provided that the evaluation unit and / or a central control or regulating unit of the plastic molding machine is designed to output the message in the form of an alarm and / or output the message in the form of a change in a control signal for the plastic molding machine . For example, if a momentarily acting injection force and / or a momentarily acting ejector force and / or a momentarily acting closing force and / or an existing tool breathing and / or a lifting of the molding tool and / or a contact of the molding tool exceeds a predetermined limit value, a control signal be issued, which the

change a process variable causes, the change in the process variable entails a change in the momentarily acting injection force and / or the momentarily acting ejector force and / or the momentarily acting closing force. The variables determined by the evaluation unit can be changed in this way in such a way that they level off again within a predetermined limit range. In other words, such a procedure can be used to control or regulate a variable determined by the evaluation unit.

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 to a central control or regulating unit of the molding machine connected to the evaluation unit. It can also be provided that the at least one evaluation unit is connected to a central control or regulation unit of the molding machine, it being possible for the tasks of the at least one evaluation unit to be partially taken over by the central control or regulation unit of the molding machine.

It can additionally or alternatively be provided that the evaluation unit is designed to output a message if a currently acting force distribution determined by the evaluation unit deviates from a predeterminable reference force distribution. Accordingly, it can be provided that if a momentarily acting force distribution deviates from a predefinable reference force distribution, the force distribution is corrected by the evaluation unit. Especially in plastic molding machines with several pull or push rods, in which the closing force is introduced via pressure pads via the pull or push rods, it can then be provided that each pressure pad can be controlled separately in order to control a force distribution.

The fact that the force distribution deviates from the reference force distribution can be understood, for example, to mean that the force distribution leaves tolerance ranges or a tolerance band around the reference force distribution.

It can preferably also be provided that the evaluation unit is or can be connected to a display device for displaying the message. For example, it can be provided that the recorded variables are displayed on a screen for the operator or that a warning signal is output only when a determined variable exceeds a predetermined limit value, which is designed as an alarm lamp, for example.

It can preferably be provided that the at least one transmitting unit and the at least one receiving unit are structurally combined in one unit and preferably the at least one transmitting unit and the at least one receiving unit are formed by the same components to fulfill a transmitting function and a receiving function.

[0051] It can be provided that the at least one component is at least one of the at least two mold mounting plates. In one embodiment it can be provided that a change in thickness (change in dimension) of at least one of the at least two mold clamping plates is measured by the ultrasonic device, the mold clamping plates being elastically deformed when a clamping force is applied. In particular, the thickness of at least one of the at least two mold mounting plates can decrease under the action of the closing force (also called compression).

However, it can also be provided that the at least one component is at least one pull or push rod penetrating the at least two mold mounting plates. In the case of molding machines with pull or push rods, for example, a change in length of the pull or push rod can be measured by means of an ultrasound device and the evaluation unit is designed to generate a pull or push force based on the change in length of the pull or push rod is transmitted by means of the pull or push rod, to determine and thus to determine a closing force which is exerted on a mold via the mold mounting plates. This procedure represents a particularly simple way of determining a clamping force distribution.

[0053] It can be provided that the at least one component is a machine frame connected to the plastics molding machine. In particular, it can also be provided that a change in dimension (or deformation) of the machine frame can be used to determine a closing force by the evaluation unit.

For example, it can also be provided that at least one molding tool is arranged between the at least two mold mounting plates, the at least one component being at least a part of the at least one molding tool.

The at least one component can preferably also be designed as a part of the closing force mechanism, the closing force mechanism preferably having a toggle lever mechanism. In an exemplary embodiment variant, it can be provided that the at least one component is a lever of the toggle lever mechanism and a change in size of the toggle lever mechanism, more precisely the lever, is determined by means of the ultrasonic device and the evaluation unit when the closing force is applied.

At least two ultrasonic devices can be provided, with at least two transmitting units and at least two receiving units on the at least one component of the closing unit which is exposed to a force by the application of the closing force and / or a counterforce opposing the closing force, and / or with a Sound-conducting connection connected to the at least one component and / or integrated into the at least one component. Alternatively or additionally, at least two ultrasonic devices can be provided, with at least two transmitting units and at least two receiving units being arranged on at least two components of the closing unit, which are subjected to a force by the application of the closing force and / or a counterforce opposing the closing force, and / or with a sound-conducting connection connected to the at least two components and / or integrated into the at least two components. An interaction between the at least two ultrasonic devices is also entirely conceivable, so that ultrasonic signals emitted by one ultrasonic device are received by the other ultrasonic device. Force profiles can be recorded particularly easily by using two or more ultrasonic devices. The use of several transmitting and / or receiving units can of course also be provided for forces other than the closing force.

It can particularly preferably be provided that the evaluation unit is designed to take separate measurements from the at least one ultrasound device

- A dimensional change of the at least one component and / or

a change in position of the at least one component and / or

- a change in the force acting on the component and / or the force against

set counterforce to determine.

It can be provided that a movement of the at least one component is thus determined.

It can be provided that two separate measurements - are carried out by the same ultrasonic device at different times and / or - are carried out by at least two ultrasonic devices.

Spatially separate measurements can be made both by moving the ultrasonic unit and by pivoting the ultrasonic unit.

In a preferred exemplary embodiment, for example, the evaluation unit can determine a closing force and / or a counterforce opposing the closing force over a longer period of time or in a time interval. For example, not only the closing force that is caused by the closing mechanism can be determined, but also during the process a force counteracting the closing force, which arises from the injection of a molding compound into the mold, measured and preferably output. Of course, other forces than the closing force can also be used

can be determined over a longer period of time or a time interval.

Preferably, it can be provided that the evaluation unit is designed to take into account a temperature - preferably determined by a temperature sensor - in the direct or indirect determination of a change in dimension and / or change in position of the at least one component. It can thus be provided that the evaluation unit takes into account a temperature expansion of the at least one component during one, during one or also between two measurements. In particular, embodiments with a plasticizing screw or a plasticizing cylinder that are exposed to high temperatures and temperature fluctuations, this can be an advantage.

Provision is preferably made for the evaluation unit to be designed to determine the change in dimension and / or the change in position of the at least one component during operation of the plastics molding machine.

Further advantages and details of the invention emerge from the figures and the associated figure descriptions, in which:

1 shows a first embodiment of a plastic molding machine according to the invention in the area of the clamping unit,

2 shows a further exemplary embodiment of a plastic molding machine according to the invention in the area of the clamping unit,

3 shows a third embodiment of a plastic molding machine according to the invention in the area of the clamping unit,

4 shows a fourth exemplary embodiment of a plastic molding machine according to the invention in the area of the clamping unit,

5 shows a fifth exemplary embodiment of a plastic molding machine according to the invention in the area of the clamping unit,

6 shows a sixth exemplary embodiment of a plastics molding machine according to the invention in the area of the clamping unit,

[0070] FIGS. 7a, 7b show the basic procedure of an evaluation unit by means of two diagrams,

8 shows a seventh exemplary embodiment of a plastic molding machine according to the invention in the area of the clamping unit and

9 shows an eighth embodiment of a plastic molding machine according to the invention in the area of the clamping unit.

Fig. 1 shows a first embodiment of a plastic molding machine - in this embodiment an injection molding machine - in the area of the clamping unit 1. A movable mold clamping plate 4 can be moved relative to a fixed mold clamping plate 3 by means of a toggle lever mechanism 2, the toggle lever mechanism 2 via a drive spindle 6 is driven.

The movable platen 4 is connected to the fixed platen 3 via the pull or push rods 5. A molding tool 13 for a molding process can be attached between the movable platen 4 and the fixed platen 3.

In order to apply a clamping force to a mold 13 between the movable platen 4 and the fixed platen 3, the cross head 9 is moved in the direction of the platen 3, 4 by means of the drive spindle 6, whereby the toggle mechanism 2 stretches and the movable platen 4 is moved in the direction of the fixed platen 3.

When the clamping force is applied to the mold 13, the pull or push rods 5 - in this exemplary embodiment pull rods - are subjected to a tensile stress.

hits, whereby the pull or push rods 5 expand in length.

In the exemplary embodiment in FIG. 1, an ultrasonic device 10 is arranged on the movable platen 4. In this exemplary embodiment, the receiving unit 10.1 and the transmitting unit 10.2 of the ultrasonic device 10 are integrated into one unit (ultrasonic device 10) and are connected to an evaluation unit 7 by means of a signal-conducting connection 8, the evaluation unit 7 also being connected to a control unit of the plastic molding machine (e.g. central machine control) or can be integrated into the control or regulation unit of the molding machine.

When measuring the ultrasonic device 10, an ultrasonic signal 12 is transmitted by the transmitting unit 10.2, with part of the ultrasonic signal 12 being reflected by the side of the movable platen 4 facing the fixed platen 3 and being received again by the receiving unit 10.1.

The evaluation unit 7 can be designed to calculate the geometric dimensions of the movable platen 4 by means of the measured elapsed time between the sending of the ultrasonic signal 12 and the reception of the ultrasonic signal 12.

If the movable platen 4 is now subjected to a closing force, which is transmitted by the movable platen 4 from the toggle mechanism 2 to the mold 13, which is located between the movable platen 4 and the fixed platen 3, there is elastic deformation of the movable platen 4 result due to the prevailing compressive stresses, the thickness of the movable platen 4 will decrease.

If a measurement is carried out by the ultrasonic device 10 during the application of the clamping force, a changed dimension of the movable platen 4 can be determined. The dimension can now be compared by the evaluation unit 7 with a stored dimension of the movable platen 4 and / or with a dimension which was determined by a reference measurement without application of the clamping force. By changing the dimensions, conclusions can now be drawn about a prevailing clamping force, for example by using Hooke's law due to the deformation, with reference to the known geometric shape and the known material of the movable platen 4, to the existing force (the clamping force) is closed.

On the basis of this established closing force currently present, the evaluation unit 7 or the machine control can now be designed to adapt the closing force to a desired closing force, more precisely to increase or decrease the closing force. This can be done by the evaluation unit 7 by changing the setpoint value, for example by controlling the drive spindle 6 or by changing the mold height via the adjusting nut 17.

2 shows a further exemplary embodiment, the ultrasonic device 10 being arranged on one of the pull or push rods 5 (in this example pull rod). Here again, the transmitting unit 10.2 and the receiving unit 10.1 are integrated in one unit. The ultrasonic device 10 is connected to the evaluation unit 7 via a signal-conducting connection. The remaining components of the closing unit 1 are analogous to those of FIG. 1. With the exemplary embodiment in FIG. 2, the ultrasonic device 10 can now measure a length of the pull or push rod 5 which will expand when the closing force is applied due to the pulling forces. In this case, an expansion can be measured by the ultrasonic device 10, it being possible to infer a closing force by means of the evaluation unit 7 based on the expansion.

The ultrasonic device 10 according to the invention is only shown on one of the pull or push rods 5. Corresponding measurements can of course be carried out on several - in particular all - pull or push rods 5, in particular in order to measure a clamping force distribution.

In FIG. 3, the same configuration of a locking unit 1 as in the previous figures is shown again. However, in FIG. 3 the ultrasonic device 10 is arranged on a molding tool 13 which is designed in two parts and has a first molding tool half 14 and a second molding tool half 15. Again, a change in dimension of at least one mold half 14, 15 can be measured by the ultrasonic device 10 under the application of a clamping force, and a clamping force can be determined by the evaluation unit 7 on the basis of the change in dimension. Furthermore, it is now possible, by means of the ultrasonic device 10, more precisely by means of the integrated receiving unit 10.1 and the integrated transmitting unit 10.2, to determine what is known as a gaping of the molding tool 13.

When the molding tool 13 opens, an air gap is formed between the first molding tool half 14 and the second molding tool half 15. However, the propagation of an ultrasonic signal 10 in air is only limited. As a result, the ultrasonic signal 10 loses its intensity when the first mold half 14 lifts off the second mold half 15. A part of the ultrasonic signal 10 is also reflected by the second mold half 15, but this is generally no longer detectable by measurement due to the attenuation of the air at the receiving unit 10.1.

Such a gaping of the molding tool 13 can therefore be detected by the ultrasonic device 10 when the reflected ultrasonic signal 12, which is reflected by the side of the second molding tool half 15 facing the first molding tool half 14, can no longer be received. As mentioned, it can be concluded from this that there is a distance between the two mold halves 14, 15. Depending on the point in time of the process, such a distance can be provided (e.g. as an embossing stroke) or it can be recognized from this that the clamping force has been selected too low and the mold 13 begins to gap and the clamping force must be increased. As an alternative to the automatic increase in the clamping force, however, a warning signal can also be output.

In FIG. 4, the clamping unit 1 already described in FIG. 1 is shown. However, in FIG. 4, several, more precisely five, ultrasonic devices 10 are provided on the movable platen 4. A receiving unit 10.1 and a transmitting unit 10.2, which are connected to an evaluation unit 7 via a signal-conducting connection 8, are in turn integrated in the ultrasonic devices 10. The provision of several ultrasonic devices 10 results in the advantage that a dimensional change of the movable mold clamping plate 4 can be determined at several positions of the movable mold clamping plate 4, whereby an uneven clamping force distribution along the movable mold clamping plate 4 can be detected and due to the deformation of the movable mold clamping plate 4 the closing force can be adjusted if necessary. An inclined position of the movable platen 4 with respect to the fixed platen 3 can also be measured by providing several ultrasonic devices 10.

In Fig. 5, an embodiment is shown in which an ultrasonic device 10 is arranged on each pull or push rod 5 of the closing unit 1, the ultrasonic devices 10 again each having a receiving unit 10.1 and a transmitting unit 10.2, which via a signal-conducting connection 8 are connected to an evaluation unit 7. Similar to FIG. 4, an uneven deformation of the closing unit 1 can also be determined by the embodiment of FIG. 5, through the provision of a plurality of ultrasonic devices 10, which provides information about an unevenly distributed closing force.

In the exemplary embodiment in FIG. 6, two ultrasonic devices 10 are each arranged on a lever of the toggle lever 2, which is part of the toggle lever mechanism 2. Here, too, a length (a geometric dimension) of the levers of the toggle lever mechanism 2 can be determined and a change in dimension under the application of a clamping force can be measured, with the evaluation unit 7 in turn being able to infer an existing clamping force based on the change in dimension or an uneven clamping force distribution (due to the two ultrasonic devices provided 10) can be determined.

7a and 7b show the basic procedure of an evaluation unit 7 by means of two

Diagrams. The ordinate of the diagrams is to be understood as the intensity X of the signals received by the receiving unit 10.1 and the abscissa as time t. To explain the diagrams in FIGS. 7a and 7b, reference is made to FIG. 1, in which the ultrasonic device 10 is arranged on a movable mold mounting plate 4.

At one time an ultrasonic signal 12.1 is transmitted by the transmitting unit 10.2 and can be received again as a reflected ultrasonic signal 12.2 by the receiving unit 10.1 after a certain period of time. The distance that the ultrasonic signal 12.2 has covered can be calculated from the time elapsed between the transmission of the ultrasonic signal 12.1 and the reception of the ultrasonic signal 12.2 with the aid of the speed of sound of the ultrasonic signal 12 in a material from which the movable platen 4 is made . If this distance is now halved (since the ultrasonic signal has covered the way there and back), the thickness of the movable platen 4 can now be determined.

This process, which is shown in FIG. 7a, is to be understood in the case of a movable platen 4 which has not been subjected to a closing force and can thus serve as a reference measurement which provides information about the thickness of a movable platen 4 without application of force.

This process is then repeated with the application of a clamping force to the movable platen 4 (this is shown by FIG. 7b). It can be seen here that an emitted ultrasonic signal 12.1 returns to the receiving unit 10.1 significantly earlier than the reflected ultrasonic signal 12.3. If the reference value of the ultrasonic signal 12.2 is now used, a time difference At between the ultrasonic signal 12.3 and the ultrasonic signal 12.2 can be detected, which in turn, with the aid of the ultrasonic signal speed in the material from which the movable platen 4 is made, can be used to deduce a change in the dimensions of the movable platen 4 can.

With the aid of this dimensional change of the movable platen 4, the evaluation unit 7 or the machine control can be designed to draw conclusions about a closing force that is exerted on the movable platen 4 on the basis of known material-specific values and dimensions.

8 shows an exemplary embodiment in which the ultrasonic unit 10 is arranged on a drive spindle 6 of the toggle lever mechanism 2. The drive spindle 6 transmits a force from the spindle nut 16 (designed as a recirculating ball screw nut in this embodiment) to the toggle lever mechanism 2, which transfers the force transmitted by the drive spindle 6 as a closing force to the movable platen 4. Here, a geometric dimension of the drive spindle 6 can be determined and a change in dimension of this length can be measured, with the evaluation unit 7 in turn being able to infer a currently present force on the basis of the change in dimension. How the basic procedure of the ultrasonic unit takes place is shown, for example, by FIGS. 7a and 7b. Again, the ultrasonic device 10 shown in FIG. 8 has integrated receiving unit 10.1 and transmitting unit 10.2. The ultrasonic unit is in turn connected to the evaluation unit 7 by a signal-conducting connection 8.

In the part of the drive spindle 6 which is located within the spindle nut 16, a non-linear deformation is to be expected, since higher forces are introduced at certain points of the spindle nut 16. Such deformation patterns are known and can be taken into account when determining the dimensional change.

Since there is a defined relationship between the force transmitted by the drive spindle 6 and the closing force introduced into the movable platen 4 by the toggle lever mechanism 2, the evaluation unit 7 can be designed, based on the change in length of the drive spindle 6, which is representative of a transmitted force the drive spindle 6 is to close to a closing force.

However, it is also possible to detect such a force, which is transmitted to the toggle lever mechanism by the drive spindle 6, by arranging an ultrasonic unit 10 on the spindle nut 16, as is shown by FIG. 9.

Austrian

REFERENCE CHARACTERISTICS LIST:

10 10.1 10.2 12 12.1 12.2 12.3 13 14 15 16 17

At

Clamping unit toggle mechanism fixed platen movable platen pull or push rod drive spindle evaluation unit signal-conducting connection crosshead ultrasonic device receiving unit transmitting unit ultrasonic signal ultrasonic signal ultrasonic signal ultrasonic signal molding tool

first mold half second mold half spindle nut adjusting nut

Intensity of the received signal time

Time difference

AT 16 801 U1 2020-09-15

Claims (34)

Expectations 1. Plastic molding machine with at least one component which is subjected to a force and / or a counterforce opposing the force by at least one drive, characterized in that at least one ultrasonic device (10) with at least one transmitting unit (10.2) for transmitting and at least one receiving unit ( 10.1) is provided for receiving ultrasound, which ultrasound device (10) is connected or connectable to an evaluation unit (7), wherein - the at least one transmission unit (10.2) is arranged on the at least one component and / or via a sound-conducting connection with the at least a component is connected and / or integrated into the at least one component and - The at least one receiving unit (10.1) is arranged on the at least one component and / or is connected to the at least one component via a sound-conducting connection and / or is integrated into the at least one component and - The evaluation unit (7) is designed to determine a change in dimension and / or a change in position of the at least one component directly or indirectly on the basis of a measurement of the at least one ultrasonic device (10) and to output a message based on the measurement which indicates the force itself and / or an effect of the force on the plastic molding machine and / or a molding tool (13) is representative. 2. Plastic molding machine according to claim 1, characterized in that the at least one component is a spindle that can be driven by the at least one drive. 3. Plastic molding machine according to claim 2, characterized in that a change in length of the spindle can be determined by the at least one evaluation unit (7). 4. Plastic molding machine according to one of claims 2 or 3, characterized in that a change in cross section of the spindle can be determined by the at least one evaluation unit (7). 5. Plastic molding machine according to one of claims 2 to 4, characterized in that the spindle is connected or can be connected to an ejector unit of the plastic molding machine. 6. Plastic molding machine according to one of claims 2 to 5, characterized in that the evaluation unit (7) is designed to output a momentarily acting ejector force as part of the message due to the specific change in dimension and / or the change in position of the spindle. 7. Plastic molding machine according to one of the preceding claims, characterized in that the at least one component is a component that can be driven by the at least one drive - preferably a plasticizing screw - of the injection unit. 8. Plastic molding machine according to claim 7, characterized in that a change in length of the drivable component of the injection unit can be determined by the at least one evaluation unit (7). 9. Plastic molding machine according to one of claims 7 or 8, characterized in that the evaluation unit (7) is designed to output a momentarily acting injection force as part of the message due to the specific change in dimension and / or the change in position of the drivable component of the injection unit. 10. Plastic molding machine according to one of the preceding claims, characterized by: - at least two mold mounting plates (3, 4) which are suitable for transmitting a closing force to a mold (13) mounted thereon and - a closing force mechanism which is designed to support the to apply the closing force to at least two mold mounting plates (3, 4), 11. 12. 13. 14th 15th 16. 17th 18th 19th 20th Austrian AT 16 801 U1 2020-09-15 wherein the at least one component is a component of the closing unit (1) which is exposed to the force caused by the application of the closing force and / or a counterforce opposing the closing force, the message to be output from the evaluation unit (7) showing an effect of the application of the closing force on the closing unit (1) and / or a mold (13) represents. Plastic molding machine according to claim 10, characterized in that the at least one drive is designed as a closing force mechanism of the plastic molding machine. Plastic molding machine according to claim 10 or 11, characterized in that the evaluation unit (7) is designed to generate a momentarily acting closing force and / or a momentarily acting force distribution based on the specific change in dimension and / or the change in position of the at least one component of the clamping unit (1) / or to determine an existing tool breathing and / or a lifting of the molding tool (13) and / or a contact of the molding tool (13) and preferably information about the momentarily acting clamping force and / or the momentarily acting force distribution and / or the existing mold breathing and / or to output a lifting of the molding tool and / or a contact of the molding tool as part of the message. Plastic molding machine according to one of claims 10 to 12, characterized in that the evaluation unit (7) is designed to output the message if a currently acting closing force determined by the evaluation unit (7) and / or an existing tool breathing and / or a lifting of the The molding tool (13) and / or a contact of the molding tool (13) exceeds and / or falls below a predeterminable limit value. Plastic molding machine according to one of Claims 10 to 13, characterized in that the at least one component is at least one of the at least two mold mounting plates (3, 4). Plastic molding machine according to one of Claims 10 to 14, characterized in that the at least one component is at least one pull or push rod (5) passing through the at least two mold mounting plates (3, 4). Plastic molding machine according to one of claims 10 to 15, characterized in that the molding tool (13) is arranged between the at least two mold mounting plates (3, 4), the at least one component being at least part of the molding tool (13). Plastic molding machine according to one of Claims 10 to 16, characterized in that the at least one component is part of the closing force mechanism, the closing force mechanism preferably having a toggle lever mechanism (2). Plastic molding machine according to one of the preceding claims, characterized in that the ultrasonic device (10) is designed to carry out a transit time measurement. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is integrated into the at least one ultrasonic device (10). Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to provide a momentarily acting force distribution and / or a lifting of the at least one component and / or a lifting of the at least one component based on the specific dimensional change and / or the position change of the at least one component To determine contact of the at least one component and preferably information about the momentarily acting force distribution and / or a lifting of the at least one component and / or a contact of the at least one component 21st 22nd 23. 24. 25th 26th 27. 28. 29 30th Austrian AT 16 801 U1 2020-09-15 component within the scope of the report. Plastic molding machine according to claim 20, characterized in that the evaluation unit (7) is designed to output the message if a momentarily acting force distribution determined by the evaluation unit (7) deviates from a predeterminable reference force distribution. Plastic molding machine according to claim 20, characterized in that the evaluation unit (7) is designed to output the message if a momentarily acting force determined by the evaluation unit (7) and / or a lifting of the at least one component and / or a contact of the at least a component exceeds and / or falls below a predeterminable limit value. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to deduce a deformation of the at least one component based on the change in dimension and / or the change in position of the at least one component and preferably information about the deformation of the at least one Output component as part of the report. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) and / or a central control or regulation unit of the plastic molding machine is designed to output the message in the form of an alarm and / or the message in the form of a change in a control signal for the plastic molding machine output. Plastic molding machine according to claim 24, characterized in that the control signal to be changed is a target value, preferably a target closing force. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is or can be connected to a display device for displaying the message. Plastic molding machine according to one of the preceding claims, characterized in that the at least one transmitting unit (10.2) and the at least one receiving unit (10.1) are structurally combined in one unit, preferably the at least one transmitting unit (10.2) and the at least one receiving unit (10.1) the same components are designed to fulfill a transmission function and a reception function. Plastic molding machine according to one of the preceding claims, characterized in that the at least one component is a machine frame connected to the plastic molding machine. Plastic molding machine according to one of the preceding claims, characterized in that at least two ultrasonic devices (10) are provided, at least two transmitting units (10.2) and at least two receiving units (10.1) on the at least one component of the plastic molding machine, which at least one component through the at least one Drive is subjected to a force and / or a counterforce opposing the force, arranged and / or connected to a sound-conducting connection with the at least one component and / or integrated into the at least one component. Plastic molding machine according to one of the preceding claims, characterized in that at least two ultrasonic devices (10) are provided, with at least two transmitting units (10.2) and at least two receiving units (10.1) on at least two components of the plastic molding machine, which at least two components through the at least one drive are exposed to a force and / or a counterforce opposing the force, arranged and / or connected with a sound-conducting connection to the at least two components and / or integrated into the at least two components. 31. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to use separate measurements of the at least one ultrasonic device (10) - a dimensional change of the at least one component and / or - a change in position of the at least one component and / or - a change in the force acting on the component and / or the force against set opposing force to determine. 32. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to take into account a temperature - preferably determined by a temperature sensor - in the direct or indirect determination of a change in dimension and / or change in position of the at least one component. 33. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to determine the change in dimension and / or the change in position of the at least one component during operation of the plastic molding machine. 34. A method for checking at least one component of a plastic molding machine, characterized in that a change in dimension and / or a change in position of at least one component of the plastic molding machine is determined directly or indirectly on the basis of a measurement by means of ultrasound and a message is output based on the measurement, which for a force and / or an effect of the force on the plastic molding machine and / or on a molding tool (13) is representative. In addition 9 sheets of drawings