DEVICE AND METHOD FOR PROCESSING THERMOPLASTIC MATERIAL WITH A TEMPERATURE CONTROL DEVICE FOR A CONVEYING SCREW

Abstract

The invention relates to a device (1a . . . 1g) for processing thermoplastic material, comprising a storage container (2)/a conveying line (11) for plastic particles and a conveying screw (3) connected thereto. The device (1a . . . 1g) further comprises an extruder (4) which connects to the conveying screw (3), and a tempering device (7) arranged in the course of the conveying screw (3). In addition, a temperature sensor (8, 8a, 8b) is arranged in the course of the conveying screw (3)/the extruder (4), and/or means (10) are provided for detecting a load of a drive (6) of the extruder (4). Finally, the device (1a . . . 1g) comprises means for influencing the tempering device (7) and an open loop control/closed loop control (9) which is connected to the at least one temperature sensor (8, 8a, 8b) and/or the influencing means of the tempering device (7). Furthermore, an operating method for the device (1a . . . 1g) is specified, in which the plastic particles are temperature-controlled by a tempering device (7) in the course of the conveying screw (3).

Claims

1-24. (canceled)

25. A device (1a . . . 1g) for processing thermoplastic material, comprising a storage container (2) for receiving plastic particles or a conveying line (11) for the transport of plastic particles, a conveying screw (3) connected to the storage container (2)/the conveying line (11) at a transfer opening (B) and an extruder (4) connecting to the conveying screw (3), a tempering device (7) arranged in the course of the conveying screw (3) and a) at least one temperature sensor (8, 8a, 8b), which is arranged in the course of the conveying screw (3) and/or in the course of the extruder (4), means for influencing the tempering device (7) and an open loop control/closed loop control (9) connected to the at least one temperature sensor (8, 8a, 8b) and to the means for influencing the tempering device (7) and/or b) means (10) for detecting a load of a drive (6) of the extruder (4), means for influencing the tempering device (7) and a closed loop control (9) connected to the detection means (10) and to the influencing means, further comprising a sensor (18) for detecting the type/sort of the processed plastic and/or an input means (21) for inputting the type/sort of the processed plastic, a memory (19) with an allocation, stored therein, between the type/sort of the plastic and in case a) a set-point temperature in the extruder (4)/at the inlet of the extruder (4), and/or in case b) a set-point load of the drive (6) of the extruder (4) and means for loading the set-point temperature/set-point load, which corresponds to the detected/inputted type/sort of the plastic, into the open loop control/closed loop control (9).

26. The device (1a . . . 1g) according to claim 25, wherein the tempering device (7) is formed by a heating device, a cooling device or a combined heating- and cooling device.

27. The device (1a . . . 1g) according to claim 26, wherein a cooling power of the cooling device or of the combined heating- and cooling device is greater than a power supplied to the plastic particles in the conveying screw (3) by friction.

28. The device (1a . . . 1g) according to claim 25, wherein the at least one temperature sensor (8, 8a, 8b) in case a) is arranged in transport direction after the tempering device (7).

29. The device (1a . . . 1g) according to claim 25, wherein the at least one temperature sensor (8, 8a, 8b) in case a) is arranged in the region of the transition between the conveying screw (3) and the extruder (4).

30. The device (1a . . . 1g) according to claim 25, wherein the closed loop control (9) in case a) is arranged to increase the heat supply through the tempering device (7) when a temperature (T) in the extruder (4)/at the inlet of the extruder (4) falls, and vice versa.

31. The device (1a . . . 1g) according to claim 25, wherein the closed loop control (9) in case b) is arranged to increase the heat supply through the tempering device (7) when a load of the extruder (4) increases, and vice versa.

32. The device (1a . . . 1g) according to claim 25, further comprising a plurality of temperature sensors (8, 8a, 8b) arranged in the transport course of the plastic particles.

33. The device (1a . . . 1g) according to claim 25, wherein in the memory (19) an allocation between the type/sort of a plastic and in case a) a set-point temperature profile along at least a portion of the transport course of the plastic particles, containing the set-point temperature in the extruder (4)/at the inlet of the extruder (4), and/or in case b) an allocation between the type/sort of a plastic and a set-point load profile along at least a portion of the transport course of the plastic particles, containing the set-point load of the drive (6) of the extruder (4), is stored and further open loop control circuits/closed loop control circuits are provided in the transport course of the plastic particles, by which the temperature (T) of the plastic particles is able to be influenced and into which the said set-point temperature profile/set-point load profile or parts thereof are able to be loaded.

34. The device (1a . . . 1g) according to claim 25, wherein the conveying screw (3) has comminution means (12, 14, 16) arranged thereon.

35. The device (1a . . . 1g) according to claim 34, wherein the comminution means are formed by teeth (12) and/or blades (14) and/or continuous cutters (16).

36. The device (1a . . . 1g) according to claim 35, wherein in the region of the conveying screw (3), fixed counter teeth (13)/counter blades (15)/counter cutters (17), interacting with its teeth (12)/blades (14)/continuous cutters (16), are arranged.

37. A method for processing thermoplastic material by means of a device (1a . . . 1g), which comprises a storage container (2) for receiving plastic particles or a conveying line (11) for the transport of plastic particles, a conveying screw (3) connected to the storage container (2)/the conveying line (11) at a transfer opening (B), and an extruder (4) connecting to the conveying screw (3), wherein the plastic particles are tempered in the course of the conveying screw (3) by a tempering device (7), wherein the type/sort of the processed plastic is identified by a sensor (18) and/or is detected via an input means (21), an allocation between the type/sort of a plastic and a set-point temperature in the extruder (4)/at the inlet of the extruder (4) and/or in a set-point load of the drive (6) of the extruder (4) is read from a memory (19) and the set-point temperature/set-point load, which corresponds to the identified/inputted type/sort of the plastic, is loaded into an open loop control/closed loop control (9) for controlling the tempering device (7).

38. The method according to claim 37, wherein the plastic particles are tempered by the supply or removal of heat via the tempering device (7).

39. The method according to claim 38, wherein the supply and/or removal of heat is adjusted or controlled as a function of a temperature (T) in the extruder (4)/at the inlet of the extruder (4).

40. The method according to claim 39, wherein the removal of heat is intensified when the temperature (T) in the extruder (4)/at the inlet of the extruder (4) rises, and vice versa.

41. The method according to claim 38, wherein the supply and/or removal of heat is adjusted or controlled as a function of a load of the extruder (4).

42. The method according to claim 41, wherein the removal of heat is intensified when the load of the extruder (4) falls, and vice versa.

43. The method according to claim 41, wherein for determining the load of the extruder (4) a rotation speed of a drive (6) of the extruder (4), a current received by this drive (6) or the torsion of a shaft in the drive (6) is measured.

44. The method according to claim 37, wherein the plastic particles are cooled in the course of the conveying screw (3) by the tempering device (7).

45. The method according to claim 37, wherein an allocation between the type/sort of a plastic and a set-point temperature profile along at least a portion of the transport course of the plastic particles, containing the set-point temperature in the extruder (4)/at the inlet of the extruder (4), and/or an allocation between the type/sort of a plastic and a set-point load profile along at least a portion of the transport course of the plastic particles, containing the set-point load of the drive (6) of the extruder (4), is read from the memory (19) and the set-point temperature profile/set-point load profile or parts thereof is loaded into further open loop control circuits/closed loop control circuits in the transport course of the plastic particles, which are provided for controlling temperature (T) of the plastic particles.

46. The method according to claim 37, wherein the temperature (T) of the plastic particles according to type/sort in their entire transport course or up to a position in the extruder (4) is constantly rising or constantly rising, but substantially constant in the course of the conveying screw (3) or constantly rising, but falling in the course of the conveying screw (3).

Description

[0054] For a better understanding of the invention, the latter is explained in further detail with the aid of the following figures.

[0055] There are shown respectively in highly simplified, diagrammatic illustration:

[0056] FIG. 1 a first exemplary and diagrammatically illustrated device for processing thermoplastic material with a tempering device and with a control via a temperature sensor in the region of the inlet into the extruder;

[0057] FIG. 2 a second exemplary device with a control via the load of the drive of the extruder;

[0058] FIG. 3 a further exemplary device with an expanded control;

[0059] FIG. 4 as FIG. 1, only with teeth and blades on the conveying screw and with a temperature sensor on the extruder nozzle;

[0060] FIG. 5 as FIG. 1, only with continuous blades on the conveying screw;

[0061] FIG. 6 a device with a sensor for identifying, and input means for inputting, the type/sort of the processed plastic;

[0062] FIG. 7 a device having several influence points in the course of the transport path of the plastic particles and

[0063] FIG. 8 temperature profiles for four different types/sorts of plastic particles along their transport path through the device.

[0064] By way of introduction, it is to be stated that in the variously described embodiments, the same parts are provided with the same reference numbers or respectively with the same component designations, wherein the disclosures contained in the entire description can be transferred correspondingly to identical parts with identical reference numbers or respectively with identical component designations. The location indications selected in the description, such as e.g. above, below, lateral etc., refer to the directly described and illustrated figure and, with a change of location, are to be transferred correspondingly to the new location.

[0065] FIG. 1 shows a device 1a for processing thermoplastic material, which comprises a storage container 2 for receiving plastic particles, and a conveying screw 3 connected to the storage container 2 at a transfer opening B, and an extruder 4 connecting to the conveying screw 3. The conveying screw 3 is driven by a first drive motor 5, and the extruder 4 is driven by a second drive motor 6. The conveying screw 3 and the extruder 4 intersect one another in the example which is shown. However, it is pointed out that FIG. 1 is a purely diagrammatic illustration, and the conveying screw 3 and the extruder 4 can also be arranged differently with respect to one another, in particular coaxially. It is also conceivable that the conveying screw 3 and the extruder 4 are driven by a single motor.

[0066] In addition to the components which have already been mentioned, the device 1a has a tempering device 7 arranged in the course of the conveying screw 3. Thereby, the conveying screw 3 or respectively the plastic particles conveyed therewith can be temperature-controlled during the conveying. Depending on the configuration of the tempering device 7, heat can be supplied to or removed from the plastic particles via the tempering device 7, whereby these are heated or cooled accordingly.

[0067] The tempering device 7 can be formed by a heating device, a cooling device or a combined heating and cooling device. Furthermore, the temperature device 7 can be operated by electrical current or by a heat carrier. In the case of operation by current, the tempering device 7 can be configured in particular as a heating coil. If the tempering device 7 is operated with a heat carrier, it can have, for example, a coiled tube which is flowed through by the heat carrier, which can be gaseous or liquid and can heat or cool the tempering device 7.

[0068] In FIG. 1 the tempering device 7 is illustrated as a heating and/or cooling sleeve arranged around the conveying screw 3. This is indeed advantageous, but not compulsory. It is also conceivable that the tempering device 7 is alternatively or additionally integrated in the shaft of the conveying screw 3. In this way, the heat transfer between the plastic particles and the tempering device 7 can take place particularly well.

[0069] In FIG. 1 the tempering device 7 is illustrated in addition somewhat in front of the inlet of the extruder 4. However, it is also conceivable that the tempering device 7 directly adjoins the extruder 4 or even projects over into the region of the extruder 4.

[0070] Generally, the supply and/or removal of heat is adjustable. For example, for this, the current which flows through a heating coil of the tempering device 7 can be adjustable, for instance with the aid of a transistor or thyristor. The adjusting of voltage and/or current of an electrical energy source connected to the heating coil would of course also be possible. If the operation with a liquid or gaseous heat carrier is provided, then the inflow to the tempering device 7 can be adjustable with the aid of a valve, which is connected into the flow or return, or else via the adjusting of an output of a pump or of a compressor, which is connected in circuit of the heat carrier. It is also conceivable that the heat carrier can be directed in an adjustable manner via a bypass. Additionally or alternatively, provision can also be made that the temperature of the heat carrier can be adjusted via a heat exchanger of a heating or cooling circuit, which is not illustrated.

[0071] Consequently, the said transistor/thyristor, the adjustable electrical energy source, the said valve, the pump/the compressor, or also the said heat exchanger can form influencing means of the tempering device 7, which are connected for example to the outlet of the open loop control/closed loop control 9 and accordingly are actuated by the open loop control/closed loop control 9.

[0072] In the example illustrated in FIG. 1, the supply and/or removal of heat can be adjusted or regulated furthermore as a function of a measured temperature. For this purpose, the device 1a has a temperature sensor 8 for detecting a temperature in the region of the inlet of the extruder 4, and a closed loop control 9 connected to the temperature sensor 8 and to the tempering device 7. The closed loop control 9 is arranged to increase the supply of heat through the tempering device 7 when the temperature at the inlet of the extruder 4 falls, and vice versa. This means that the tempering device 7 is heated when a temperature at the inlet of the extruder 4 falls, and is cooled when a temperature rises there.

[0073] Through the above-mentioned variant of the device 1 a, a representative for the case designated by a is realized. This means that at least one temperature sensor 8 is arranged in the course of the conveying screw 3 and/or in the course of the extruder 4, and means for influencing the tempering device 7 and an open loop control/closed loop control 9 connected with the at least one temperature sensor 8 and with the influencing means of the tempering device 7 are provided.

[0074] In the example which is shown, the temperature sensor 8 is in practical terms arranged in the transport direction of the conveyed plastic particles after the tempering device 7. In this way, a presettable (set-point) temperature of the plastic particles delivered to the extruder 4 can be regulated and can thereby be maintained particularly well.

[0075] Basically, however, it is also possible that the temperature sensor 8 is arranged before the tempering device 7 in transport direction. In this case, for example, a control can be provided for the tempering device 7, which controls the power of the tempering device 7 by means of the temperature of the delivered plastic particles. It is also conceivable that temperature sensors 8 are arranged before the tempering device 7 and after the tempering device 7.

[0076] Through the proposed provisions, a set-point temperature can be reached with a high degree of reliability in the extruder 4 and/or at the inlet of the extruder 4. By means of the tempering device 7, material supplied to the extruder 4 can be heated, for example when this has been delivered with a very low temperature and/or has a high thermal capacity and/or has a high melting temperature, and/or has not been heated in the expected manner through friction, shearing work and compression in the conveying tube. In particular, however, it is also conceivable that the plastic particles which are fed to the extruder 4 are cooled by means of the tempering device 7, for example when material has been delivered at a very high temperature and/or has a low thermal capacity and/or has a lower melting temperature and/or has been heated excessively by friction, shearing work and compression in the conveying tube.

[0077] FIG. 2 shows now a device 1b, which is very similar to the device 1a shown in FIG. 1. In contrast thereto, the closed loop control 9, however, is not connected to the temperature sensor 8, but rather to means 10 for detecting a load of the drive 6 of the extruder 4. Accordingly, the supply and/or removal of heat in the example illustrated in FIG. 2 is adjusted or regulated as a function of a load of the extruder 4. In particular, the supply of heat is increased when the load of the extruder 4 increases, and vice versa. This means that the tempering device 7 is heated when the load of the extruder 4 increases, and is cooled when the load of the extruder 4 falls.

[0078] Through the said variant of the device 1b, a representative is realized for the case designated by b. This means that means 10 for detecting a load of a drive 6 of the extruder 4, means for influencing the tempering device 7 and a closed loop control 9 connected to the detection means 10 and to the influencing means are provided.

[0079] To determine the load of the extruder 4, the detection means 10 can be configured as a sensor for measuring a rotation speed of the drive 6 of the extruder 4 (e.g. as a digital incremental encoder), as a sensor for measuring a current received by this drive 6 (e.g. as a voltage meter on a current-sensing resistor), or as a sensor for measuring the torsion of a shaft in the drive 6 (e.g. as a measuring bridge with strain gauge). When the rotation speed of the drive 6 decreases, the current received by the drive 6 increases, or the torsion of a shaft in the drive 6 increases, this is an indication of a more intensive load of the extruder 4.

[0080] At this point, it is pointed out that the drive 6 is not necessarily solely a motor, but rather the drive 6 can also, for example, have a gear unit. The above-mentioned rotation speed and the above-mentioned torsion can therefore also be taken at a component in the gear unit.

[0081] FIG. 3 shows now a further example of a device 1c, which is very similar to the devices 1a and 1b illustrated in FIGS. 1 and 2. In the device 1c, the closed loop control 9 is connected both to a temperature sensor 8 of the extruder 4 and also to means 10 for detecting a load of the drive 6 of the extruder 4. Control of the tempering device 7 can therefore take place in a particularly differentiated manner.

[0082] In the device 1c in particular also the drive motor 5 of the conveying screw 3 is connected to the control unit 9 and is integrated into the open loop control/closed loop control of the device 1c. For example, the rotation speed of the conveying screw 3 can be lowered when load of the extruder 4 increases and vice versa, in particular synchronously to an increase of the temperature.

[0083] In contrast to FIG. 1, the temperature sensor 8 is arranged in the region of the outlet of the extruder 4. Thereby, the closed loop control 9 can regulate the temperature at the outlet of the extruder 4, whereby the proper melting of the plastic particles can be controlled well. Of course, the temperature sensor 8 could, however, also be arranged at the inlet of the extruder 4, as is illustrated in FIG. 1.

[0084] It can also be seen from FIG. 3 in particular that the device 1c does not necessarily have a container 2, but rather the conveying screw 3, as illustrated, can be connected to a conveying tube 11. Via the conveying tube 11, plastic particles are not only conveyed to the conveying screw 3, but also to other (not illustrated) units. In particular, the transport direction occurs from top to bottom. Through the movement of the plastic particles and the projection protruding into the conveying tube 11, some of the material transported in the conveying tube 11 cam be branched off and conveyed into the conveying screw 3.

[0085] In the examples shown hitherto, the conveying screw 3 is aligned in horizontal direction and the transfer opening B is aligned in vertical direction. This is, indeed, advantageous, but is not compulsory. Generally, it is of course also conceivable that the conveying screw 3 and/or the cross-section of the transfer opening B are aligned obliquely.

[0086] Generally, it is also advantageous if the conveying screw 3 has radially arranged cutters, blades or teeth. In this way, the material which is conveyed into the conveying screw 3 can be further comminuted before it reaches the extruder 4. The conveying screw 3 can therefore also be regarded (partly) as a processing drum/comminution screw, or can respectively include this function.

[0087] FIG. 4 shows by means of a device 1d, which corresponds substantially to the device 1a illustrated in FIG. 1, how such a conveying screw 3 can be configured. In practical terms, the conveying screw 3 of the device 1d comprises teeth 12 and counter teeth 13 and blades 14 and counter blades 15, wherein the teeth 12 and counter teeth 13 are arranged more in the front region of the conveying screw 3, and the blades 14 and counter blades 15 are arranged in the end region of the conveying screw 3. In this way, the material conveyed into the conveying screw 3 is further comminuted before it reaches the extruder 4. Therefore, material of optimium size can be fed to the extruder 4, whereby a proper intermixing and a proper melting of the material can be guaranteed and a clogging of the extruder 4 can be prevented.

[0088] In contrast to FIG. 1, in addition to a temperature sensor 8a arranged in the region of the inlet of the extruder 4, a further temperature sensor 8b is provided, which is arranged in the region of the nozzle of the extruder 4 (cf. also FIG. 3). Thereby, both the temperature of the plastic particles at the inlet of the extruder 4 and also their temperature at the outlet of the extruder 4 can be taken as the basis for the closed loop control 9. The process of preparing the plastic particles can therefore be controlled particularly well. In particular, a heating (not illustrated) of the extruder 4 can be connected to the closed loop control 9. Thereby, a first control loop can be formed, which comprises the first temperature sensor 8a and the tempering device 7, and a second control loop can be formed which comprises the second temperature sensor 8b and the extruder heating. The two control loops can operate independently of each other, or a further control loop can be superordinate to these.

[0089] FIG. 5, finally, shows an example of a device 1c which is very similar to the device 1d illustrated in FIG. 4. In this variant, however, the conveying screw 3 has no teeth 12 and no blades 14, but rather has continuous cutters 16. These cutters 16 interact with fixed cutters 17, whereby the supplied material is also comminuted.

[0090] The fixed cutters 17 can be configured, for example, as axially aligned cutters (see also the front view B) or else likewise can run helically (see the front view C). It is particularly advantageous if the pitch of the fixed helical cutters 17 is different to that of the cutters 16 of the conveying screw 3, because then load peaks in the drive torque are prevented. The helical cutters 17 can be wound in the same direction as the cutters 16 of the conveying screw 3 or else in the opposite direction thereto. Finally, it would also be conceivable that the fixed cutters 17 stand in a normal manner to the axis of the conveying screw 3.

[0091] Generally, it is advantageous if the fixed cutters 17 are arranged only in the upper and in the lateral region of the conveying screw 3, because in this way it is prevented that material collects in the lower region of the conveying screw 3, which material is not transported away. In addition, the tube in which the conveying screw 3 runs tapers in a funnel shape, whereby the drawing in of the plastic particles into the conveying screw 3 is promoted. Of course, the said eccentric configuration and/or the said funnel-shaped structure is also suitable for the teeth 12 and blades 14 illustrated in FIG. 4. Conversely, an arrangement coaxial to the conveying screw 3 and/or a cylindrical arrangement is also possible for the cutters 17 of FIG. 5. Finally, it is also conceivable that the conveying screw 3 has cutters 12, blades 14 and teeth 16 or any desired combination thereof.

[0092] FIG. 6 shows now a further variant of a device 1f, which has a sensor 18 for identifying the type/sort of the processed plastic, a memory 19 with an allocation, stored therein, between the type/sort of the plastic and a set-point temperature in the extruder 4 and/or at the inlet of the extruder 4 and means for loading the set-point temperature, which corresponds to the identified type/sort of the plastic, into the open loop control/closed loop control 9. In the example which is shown, the memory 19 and the open loop control/closed loop control 9 are part of a process computer 20. Of course, the memory 19 and the open loop control/closed loop control 9 can also form independent units.

[0093] In this variant, the temperature at the temperature sensor 8 is therefore not only regulated, but also it is established which set value is to be taken as the basis for the control. Basically, various sensors 18 can be used for detecting the type/sort of the plastic. For example, it can operate according to the principle of spectral analysis. Under certain circumstances, a continuous determining of the type/sort of the plastic is not possible or is only possible to a restricted extent owing to the required measurement time. It is therefore also conceivable that the measurement is carried out at the start of a batch, and the result forms the basis of the following processing.

[0094] Through the proposed provisions, the most varied of materials can be processed in an advantageous manner. This is advantageous in particular in connection with devices 1f, which are used for the recycling of plastic, because there a particularly large number if different plastics accumulate. Often, it is not even known which plastic or respectively which plastic mixtures are to be processed. However, by the use of the above-mentioned sensor 18, the type/sort of the processed plastic can be established and the device if can be adjusted thereto.

[0095] In the presented variant, control can take place generally, as stated above, by means of the set-point temperature in the extruder 4 and/or at the inlet of the extruder 4, when in the course of the conveying screw 3 and/or in the course of the extruder 4 a temperature sensor 8, 8a, 8b is arranged (case a). Additionally or alternatively, control can also take place by means of a set-point load of the drive 6 of the extruder 4 when means 10 are provided for detecting a load of the drive 4 of the extruder 6 (case b).

[0096] Alternatively or additionally to the sensor 18, input means 21 can also be provided for inputting the type/sort of the processed plastic, as is illustrated in FIG. 6. In this way, the type/sort can be inputted by a machine operator, for example by his selecting one or more plastics from a presented table. For example, the results of a laboratory analysis or information from a supplier can form the basis of the input. The input means 21 can be formed for example by a keyboard, a touchscreen or, for example, also by a reading device for a storage medium, on which the type/sort of the processed plastic and, if applicable, also the allocation to a set-point temperature/set-point load is stored.

[0097] In addition to the above statements, it is also noted that in the memory 19 also an allocation between the type/sort of a plastic and a set-point temperature profile along at least a portion of the transport course of the plastic particles, containing the set-point temperature in the extruder 4 and/or at the inlet of the extruder 4, can be stored. In addition, further open loop control circuits/closed loop control circuits can be provided in the transport course of the plastic particles, by which the temperature of the plastic particles is able to be influenced, and into which the said set-point temperature profile or parts thereof are able to be loaded.

[0098] In this variant, therefore, not only a single set-point temperature is prescribed selectively, but rather a set-point temperature profile along at least a portion of the transport course of the plastic particles, which leads at least through the conveying screw 3 and the extruder 4. Thereby, the device if can be adjusted even better to the type/sort of the processed plastic.

[0099] FIG. 7 shows an example for this, in which the open loop control/closed loop control 9 has influence at several points of a device 1g, as is illustrated in a simplified manner by dashed arrows. For this purpose, several temperature sensors 8, 8a, 8b (not illustrated explicitly in FIG. 7) can be provided, arranged in the transport course of the plastic particles. In FIG. 7, furthermore, a comminution shaft 22 is provided, able to be driven independently of the conveying screw 3, with blades arranged thereon. For the drive thereof, the device 1g therefore also comprises a further motor 23. By means of this comminution- or blade shaft 22, the size of the plastic particles delivered to the extruder can be adjusted independently of the material flow through the conveying screw 3. When the rotation speed of the comminution- or blade shaft 22 is increased with respect to the rotation speed of the conveying screw 3, the plastic particles are comminuted more intensively, and vice versa.

[0100] In particular, the temperature of the plastic particles, depending on the type/sort, in the entire transport course thereof up to a position in the extruder 4, can be [0101] constantly increasing or [0102] constantly increasing, but substantially constant in the course of the conveying screw or [0103] constantly increasing, but falling in the course of the conveying screw,
as is illustrated by way of example in FIG. 8. In practical terms, FIG. 8 shows several temperature profiles through the device 1g. In practical terms, the temperatures T are presented at several points A . . . F distributed over the path s. Point A designates here the inlet of the storage container 2, point B the inlet to the comminution- or blade shaft 22, point C the inlet to the conveying screw 3, point D the inlet to the extruder 4, point E a location in the extruder 4 and point F the outlet or respectively the nozzle of the extruder 4.

[0104] In practical terms, the temperature profiles for four different materials M1 . . . M4 are presented. For the materials M1 and M2, the temperature T is rising constantly in the entire transport course up to position E. These profiles are suitable in particular for plastics to which relatively little energy is supplied through friction in the conveying screw 3, or respectively plastics which have a comparatively high melting point. For example, for the material M1 polyethylene terephthalate (PET) can be provided, and polyamide (PA) for the material M2.

[0105] For the materials M3 and M4, the temperature T is rising constantly in the entire transport course up to the position E, but is falling in the course of the conveying screw 3. These profiles are suitable in particular for plastics to which a relatively large amount of energy is supplied through friction in the conveying screw 3, or respectively plastics which have a comparatively low melting point. For example, polyolefin can be provided for the material M3, and ethylene vinyl acetate (EVA) for material M4.

[0106] The materials M3 and M4 are therefore cooled by the tempering device 7 in the course of the conveying screw 3, in order to prevent or at least reduce a clogging or sticking of the extruder opening D or respectively a sticking of the plastic particles thereon. In this connection, it is also advantageous in particular if a cooling power of the tempering device 7 is greater than a power supplied to the plastic particles in the conveying screw 3 through friction. In a further preferred variant, the cooling power of the tempering device 7 is greater than a drive power of the conveying screw 4. The latter is generally easier to determine than a power supplied to the plastic particles in the conveying screw 4 through friction, whereby also the dimensioning of the tempering device 7 is simplified. A slight oversizing which has possibly taken place thereby can serve as security.

[0107] In the present example, reference was made to a transport path up to the position E. Starting from this position E, the temperature T no longer increases up to the nozzle F. However, it is also conceivable that the temperature T also increases from the position E up to the nozzle F. In this case, the above considerations apply for the entire transport path of the plastic particles through the device 1g.

[0108] In the above example, the presented method is carried out on the basis of a set-point temperature profile and with the aid of several temperature sensors 8, 8a, 8b arranged in the transport course of the plastic particles. Generally, however, it is also conceivable that the addressed method is carried out in an analogous manner alternatively or additionally by means of a set-point load profile. This is possible in particular when several drive motors are integrated into the transport course of the plastic particles. In the illustrated examples, these are the first drive 5 for the conveying screw 3, the second drive 6 for the extruder 4 and the motor 23 for comminution shaft/blade shaft 22. However, it would also be conceivable that the melting of the plastic particles takes place in several extruder stages, driven independently of one another, or the transport of the plastic particles is provided by several conveying screws 3 driven independently of one another. In this case, the set-point loads of these drives can also be integrated into the set-point load profile.

[0109] The example embodiments show possible variant embodiments of a device 1a . . . 1g for processing thermoplastic material, and methods for their operation, wherein at this point it is noted that also various combinations of the individual variant embodiments with one another are possible.

[0110] In particular, it is pointed out that the presented control principles are not necessarily linked to the mechanical characteristics of the structural form of the device 1a . . . 1g which was selected for illustration. This means that the examples are exchangeable with one another with regard to their characteristics concerning control technique, and as regards their mechanical structure. For example, the control principle presented in FIG. 1 can also be applied with a conveying screw 3 according to FIG. 4 or 5 or respectively in connection with a conveying tube 11. The control principle illustrated in FIG. 3 can also be applied in devices 1a, 1b, 1d, 1e, 1f, 1g and so on.

[0111] In particular, it is noted that a device 1a . . . 1g in reality can also comprise more or fewer components than are illustrated.

[0112] Finally, for the sake of good order, it is also pointed out that for a better understanding of the structure of the device 1a . . . 1g, the latter, or respectively its components, have partly been illustrated not to scale and/or enlarged and/or reduced in size.

[0113] The problem forming the basis of the independent inventive solutions can be taken from the description.

REFERENCE LIST

[0114] 1a . . . 1g device for processing thermoplastic material [0115] 2 storage container [0116] 3 conveying screw [0117] 4 extruder [0118] 5 first drive (for conveying screw) [0119] 6 second drive (for extruder) [0120] 7 tempering device [0121] 8, 8a, 8b temperature sensor [0122] 9 open loop control/closed loop control [0123] 10 detection means for the load of the extruder [0124] 11 conveying tube [0125] 12 teeth (on conveying screw) [0126] 13 counter teeth [0127] 14 blade (on conveying screw) [0128] 15 counter blade [0129] 16 continuous cutters (on conveying screw) [0130] 17 counter cutters [0131] 18 sensor for detecting the type/sort of the plastic [0132] 19 table/memory with allocation of plastic type/sort vs. set-point temperature/set-point load [0133] 20 process computer [0134] 21 input means for inputting the type/sort of the plastic [0135] 22 comminution shaft/blade shaft [0136] 23 motor for comminution shaft/blade shaft [0137] A storage container inlet [0138] B transfer opening/inlet to the comminution shaft/blade shaft [0139] C inlet to the conveying screw [0140] D inlet to the extruder [0141] E position within extruder [0142] F extruder outlet/nozzle [0143] M1 . . . . M4 material [0144] s path [0145] T temperature