EP3458244A1 - Method and assembly for the open-loop and closed-loop control of pipe extrusion systems - Google Patents

Method and assembly for the open-loop and closed-loop control of pipe extrusion systems

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Publication number
EP3458244A1
EP3458244A1 EP17728443.7A EP17728443A EP3458244A1 EP 3458244 A1 EP3458244 A1 EP 3458244A1 EP 17728443 A EP17728443 A EP 17728443A EP 3458244 A1 EP3458244 A1 EP 3458244A1
Authority
EP
European Patent Office
Prior art keywords
extrusion
calibration device
tube
pipe
data
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP17728443.7A
Other languages
German (de)
French (fr)
Inventor
Roland Böhm
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Inoex GmbH
Original Assignee
Inoex GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Inoex GmbH filed Critical Inoex GmbH
Publication of EP3458244A1 publication Critical patent/EP3458244A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/907—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article using adjustable calibrators, e.g. the dimensions of the calibrator being changeable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/325—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles being adjustable, i.e. having adjustable exit sections
    • B29C48/327—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles being adjustable, i.e. having adjustable exit sections with centering means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
    • B29C48/903—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies externally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/92—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92114—Dimensions
    • B29C2948/92123—Diameter or circumference
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92114—Dimensions
    • B29C2948/92152—Thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92114—Dimensions
    • B29C2948/92171—Distortion, shrinkage, dilatation, swell or warpage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92323—Location or phase of measurement
    • B29C2948/92447—Moulded article
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92819—Location or phase of control
    • B29C2948/92857—Extrusion unit
    • B29C2948/92904—Die; Nozzle zone

Definitions

  • the present invention relates to a method for the regulation and control of pipe extrusion plants according to the preamble of claim 1.
  • a plastic granulate is melted by means of an extruder and pressed in an extrusion die through an annular gap which is formed by a nozzle and a mandrel arranged therein.
  • the hot melt tube produced in this way is pressed and cooled in a subsequent calibration device under negative pressure against an external calibration device, usually a calibration sleeve.
  • the calibrated and cooled tube is drawn by means of a draw-off device from the extrusion die through the calibration device and optionally through further extrusion follower devices.
  • the annular gap of the extrusion tool is greater than the diameter of the vacuum device operating with negative pressure, so that the molten tube can run in excess and seal the calibration device against the ambient pressure.
  • the inlet angle of the melt tube into the calibration device is important, which can be influenced by the distance between the extrusion tool and the calibration device. If the oversize is too small or the inlet angle is too low, it is no longer possible to seal the calibration device against the ambient pressure. If the excess is too large or the inlet angle too steep, the molten tube is stretched too fast, which can lead to stresses in the finished tube or even cracking of the melt tube before or in the calibration.
  • DDR Dimension Draw Down
  • DDR (nozzle -DKali) / D nozzle.
  • This value should be between 5% and 50% for the most important plastic pipe material HDPE (high-density polyethylene) according to the prior art.
  • the wall thickness of the extruded tube since the outer diameter is fixed by the calibrator, results from the mass flow rate of the extruder and the speed with which the tube is pulled by the extraction device.
  • the melt tube is drawn on the one hand to the diameter of the calibration device, but at the same time depending on the speed of the trigger wall thickness of the melt Hose reduced. This double stretching of the melt tube is only possible within limits and is described by the characteristic dimension ration balance (DRB):
  • This value should be between 0.97 and 1.095 for the most important plastic pipe material HDPE (high-density polyethylene) according to the prior art.
  • the hot, soft melt hose in the extrusion plant must always be in train, so as not to accumulate in the plant. At the same time the train must not be too high, because otherwise the melt tube constricts and tears off.
  • the pull acting on the molten tube is described by the ratio of the exit area of the melt from the tool to the entrance surface of the molten tube into the calibrator
  • This value should be between 130% and 700% for the most important plastic pipe material HDPE (high-density polyethylene) according to the prior art.
  • HDPE high-density polyethylene
  • the diameter, the wall thickness, any shape deviations and the sagging of the melt tube are determined at several points between the extrusion tool and the calibration device.
  • four major effects in pipe extrusion can be included in the design of the extrusion tool, which were previously not considered.
  • these measurement data can be used for optimum centering of the nozzle and mandrel of the extrusion tool as well as for setting an optimal inlet angle of the molten tube into the calibration device.
  • optical or fully electronic terahertz or gigahertz measuring technology is used to acquire the measured data. Since this type of measurement technique operates without contact and without coupling medium, a measurement can also be made on hot, contact-sensitive bodies, such as a molten tube, directly after the extrusion tool in the tube extrusion.
  • Fig. 1 shows an extrusion plant for the production of plastic pipes with their main components in a schematic representation
  • Fig. 2 is a very schematic representation of a forming between the output of the extrusion die and the inlet of the calibration sleeve melt tube.
  • the extrusion line for plastic pipe shown in Figure 1 comprises an extruder unit 1 with a feed hopper 2, via which the extruder unit 1, a thermoplastic resin in granular or powder form is fed.
  • the extruder unit 1 the granulate or the powder is warms, kneads and plasticizes. Subsequently, the plastic is conveyed as a moldable material in an extrusion die 3 and pressed there through an annular gap 1 1.
  • the thus formed, still deformable melt tube 4 'runs with oversize in a calibration device 6, which has a vacuum tank 7 with a arranged at the input, perforated Kalibrierhülse 8.
  • the calibration sleeve 8 is infinitely adjustable in diameter, so that the extruded tube 4 can be fixed to the desired outer diameter.
  • the tube 4 After leaving the calibration device 6, the tube 4 enters a cooling section 9, in which it is cooled to about room temperature.
  • a saw 10 At the end of the extrusion line a saw 10 is arranged, in which the extruded tube 4 is cut to a predetermined length.
  • the produced pipe 4 is pulled by means of a take-off unit 5 through the upstream facilities of the extrusion plant.
  • the melt tube 4 'emerging from the annular gap 1 1 formed between a nozzle 12 and a mandrel 13 of the extrusion die 3 passes into the calibration sleeve 8 of the calibrating device 6 with an oversize.
  • the calibration device 6 Immediately after exiting the extrusion die 3 and immediately before entering the calibration sleeve 8, the calibration device 6 has a plurality of gigahertz or terahertz sensors 14 distributed over the circumference of the melt tube 4 '. By means of these sensors 14, the geometric data of the molten tube 4 'are determined. Thus, the distances between the sensors 14 and the molten tube 4 'are measured, from which the diameter of the molten tube 4' and its sagging can be calculated. Furthermore, the wall thickness of the melt tube 4 'is measured at the positions of the sensors 14, and distributed from the measured differences over the circumference, determines the eccentricity of the wall thickness.
  • the inlet angle of the molten tube 4 'into the calibrating device 6 can be calculated by comparing the distance measured values of the sensors 14 after the extrusion die 3 and before the calibrating device 6.
  • the sagging of the plastic melt after the exit from the extrusion die 3 are calculated.
  • the measured data obtained or the values calculated therefrom can be used in a variety of ways to optimize the process.
  • by the measurement data with suitable algorithms via the plant control either automatically make a correction of the control variables or suggest a detailed graphical user interface (GUI) the operator detailed settings.
  • GUI graphical user interface
  • the measured data obtained can also be used to optimize the design of the extrusion tool 3, especially for calculating the optimum annular gap geometry for a wide range of applications.
  • the actual measured diameter and wall thickness of the enlarged by the strand expansion melt tube 4 ' incorporated into the interpretation.

Abstract

The invention relates to a method for the open-loop and closed-loop control of pipe extrusion systems, taking into consideration measurement data of a produced pipe (4), wherein the excess of a molten pipe (4') passing out of a ring gap (11) of an extruder unit (1) runs into a subsequent calibration device (6). The object of the invention is to provide a method of this type which works with measurement values that guarantee an optimal operation of the extrusion system, even in the event of a change in dimension. The object is achieved in that the diameter, the wall thickness, possible shape deviations and the slackness of the molten pipe (4') is determined exactly at multiple points between the extrusion tool (3) and the calibration device (6), and these measurement values or the data calculated therefrom are used for the open-loop and closed-loop control of the extrusion system.

Description

VERFAHREN UND ANORDNUNG ZUR REGELUNG UND STEUERUNG VON ROHREXTRUSIONSAN LAGEN  METHOD AND ARRANGEMENT FOR CONTROLLING AND CONTROLLING RAW REXTRUSION LAYERS
Die vorliegende Erfindung betrifft ein Verfahren zur Regelung und Steu- erung von Rohrextrusionsanlagen gemäß dem Oberbegriff des Anspruchs 1 . The present invention relates to a method for the regulation and control of pipe extrusion plants according to the preamble of claim 1.
Bei einer Rohrextrusion wird mittels eines Extruders ein Kunststoffgra- nulat aufgeschmolzen und in einem Extrusionswerkzeug durch einen Ringspalt gepresst, der durch eine Düse und einen darin angeordneten Dorn ge- bildet ist. Der so erzeugte heiße Schmelzeschlauch wird in einer nachfolgenden Kalibiervorrichtung unter Unterdruck gegen eine Außenkalibrier-einrich- tung, meistens eine Kalibrierhülse, gepresst und abgekühlt. Das kalibrierte und abgekühlte Rohr wird mittels einer Abzugsvorrichtung aus dem Extrusionswerkzeug durch die Kalibriervorrichtung und gegebenenfalls durch wei- tere Extrusionsnachfolgeeinrichtungen gezogen. In a tube extrusion, a plastic granulate is melted by means of an extruder and pressed in an extrusion die through an annular gap which is formed by a nozzle and a mandrel arranged therein. The hot melt tube produced in this way is pressed and cooled in a subsequent calibration device under negative pressure against an external calibration device, usually a calibration sleeve. The calibrated and cooled tube is drawn by means of a draw-off device from the extrusion die through the calibration device and optionally through further extrusion follower devices.
In diesem Verfahren ist der Ringspalt des Extrusionswerkzeuges größer als der Durchmesser der mit Unterdruck arbeitenden Kalibiervorrichtung, damit der Schmelzeschlauch mit Übermaß einlaufen und die Kalibrier-vorrich- tung gegen den Umgebungsdruck abdichten kann. Neben dem Übermaß ist auch der Einlaufwinkel des Schmelzeschlauches in die Kalibrier-vorrichtung wichtig, was durch den Abstand zwischen dem Extrusionswerkzeug und der Kalibriervorrichtung beeinflusst werden kann. Bei zu geringen Übermaß oder zu flachen Einlaufwinkel ist keine Abdichtung der Kalibriervorrichtung gegen den Umgebungsdruck mehr möglich. Ist das Übermaß zu groß bzw. der Einlaufwinkel zu steil, so wird der Schmelzeschlauch zu schnell verstreckt, was zu Spannungen im fertigen Rohr oder sogar zum Reißen des Schmelzeschlauches vor oder in der Kalibriervorrichtung führen kann. In this method, the annular gap of the extrusion tool is greater than the diameter of the vacuum device operating with negative pressure, so that the molten tube can run in excess and seal the calibration device against the ambient pressure. In addition to the oversize, the inlet angle of the melt tube into the calibration device is important, which can be influenced by the distance between the extrusion tool and the calibration device. If the oversize is too small or the inlet angle is too low, it is no longer possible to seal the calibration device against the ambient pressure. If the excess is too large or the inlet angle too steep, the molten tube is stretched too fast, which can lead to stresses in the finished tube or even cracking of the melt tube before or in the calibration.
Zum Fahren der Extrusionsanlage werden Auslegekriterien verwendet, wobei nach dem Stand der Technik als Messtechnik das Ultraschallmessverfahren zur Anwendung kommt, wie z.B. in der DE 10 2006 056 735 A1 beschrieben. For driving the extrusion line, laying criteria are used, whereby according to the state of the art the ultrasonic measuring method is used as measuring technique, e.g. in DE 10 2006 056 735 A1.
Eines der Auslegekriterien ist das Übermaß, mit dem der Schmelzeschlauch in die Kalibriervorrichtung einläuft. Es wird mit dem Kennwert Dimension Draw Down (DDR) beschrieben: One of the design criteria is the oversize with which the melt tube enters the calibrator. It is described with the Dimension Draw Down (DDR) parameter:
DDR=( Düüse -DKali)/DDüse. DDR = (nozzle -DKali) / D nozzle.
Dieser Wert sollte für den wichtigsten Kunststoff-Rohrwerkstoff HDPE (Polyethylen mit hoher Dichte) gemäß dem Stand der Technik zwischen 5% und 50% liegen. This value should be between 5% and 50% for the most important plastic pipe material HDPE (high-density polyethylene) according to the prior art.
In dieser und den nachstehenden Formeln bedeuten: In this and the following formulas mean:
Düüse Außendurchmesser Düse  Nozzle outside diameter nozzle
DKaii Innendurchmesser Kalibrierhülse  DKaii inner diameter calibration sleeve
dspait Ringspalt Extrusionswerkzeug  dspait annular gap extrusion tool
dRohr Wandstärke Rohr  the pipe wall thickness tube
Die Wandstärke des extrudierten Rohres ergibt sich, da der Außendurchmesser durch die Kalibriervorrichtung fixiert wird, aus dem Massedurchsatz des Extruders und der Geschwindigkeit, mit der das Rohr von der Abzugsvorrichtung gezogen wird. Hierbei wird, ausgehend von dem Ringspalte des Extrusionswerkzeuges, der Schmelzeschlauch zum einen auf den Durchmesser der Kalibriervorrichtung gezogen, gleichzeitig aber in Abhängigkeit von der Geschwindigkeit des Abzugs die Wandstärke des Schmelze- Schlauches reduziert. Dieses doppelte Verstrecken des Schmelzeschlauches ist nur in Grenzen möglich und wird durch den Kennwert Dimension Ration Balance (DRB) beschrieben: The wall thickness of the extruded tube, since the outer diameter is fixed by the calibrator, results from the mass flow rate of the extruder and the speed with which the tube is pulled by the extraction device. Here, starting from the annular gap of the extrusion die, the melt tube is drawn on the one hand to the diameter of the calibration device, but at the same time depending on the speed of the trigger wall thickness of the melt Hose reduced. This double stretching of the melt tube is only possible within limits and is described by the characteristic dimension ration balance (DRB):
Düüse / DKali Düüse / DKali
DRB =  DRB =
(Düüse - dspalt) / (DKali - dRohr)  (Düüse - dspalt) / (DKali - dTube)
Dieser Wert sollte für den wichtigsten Kunststoff-Rohrwerkstoff HDPE (Polyethylen mit hoher Dichte) gemäß dem Stand der Technik zwischen 0,97 und 1 ,095 liegen. This value should be between 0.97 and 1.095 for the most important plastic pipe material HDPE (high-density polyethylene) according to the prior art.
Darüber hinaus ist zu beachten, dass der heiße, weiche Schmelzeschlauch in der Extrusionsanlage immer unter Zug stehen muss, um sich nicht in der Anlage aufzustauen. Gleichzeitig darf der Zug nicht zu hoch sein, da sich der Schmelzeschlauch sonst einschnürt und abreißt. Der Zug, der auf den Schmelzeschlauch wirkt, wird durch das Verhältnis der Austrittsfläche der Schmelze aus dem Werkzeug zur Eintrittsfläche des Schmelzeschlauchs in die Kalibriervorrichtung beschrieben In addition, it should be noted that the hot, soft melt hose in the extrusion plant must always be in train, so as not to accumulate in the plant. At the same time the train must not be too high, because otherwise the melt tube constricts and tears off. The pull acting on the molten tube is described by the ratio of the exit area of the melt from the tool to the entrance surface of the molten tube into the calibrator
Awerkzeug Ddüse2 - (Düüse - dspalt)2 A die nozzle 2 - (nozzle - gap) 2
ARohr DKali2 - (DKali - dRohr)2 ARohr DKali 2 - (DKali - dRohr) 2
Dieser Wert sollte für den wichtigsten Kunststoff-Rohrwerkstoff HDPE (Polyethylen mit hoher Dichte) gemäß dem Stand der Technik zwischen 130% und 700% liegen. Um den Aufwand für Rüstvorgänge bei dem Wechsel von einer Rohrdimension (Durchmesser und Wandstärke) auf eine andere zu reduzieren, ist es von großem Nutzen, wenn der Ringspalt des Extrusionswerkzeuges optimiert auf möglichst viele Produktvarianten abgestimmt ist. Gerade wenn im Prozess zusätzlich noch eine verstellbare Kalibriervorrichtung eingesetzt wird, kann mit einer so optimierten Auslegung des Extrusionswerkzeuges ein großes Produktfenster ohne Anlagenstopp und Umbauarbeiten abgedeckt werden. Die oben angeführten Auslegekriterien sind dafür unzureichend. This value should be between 130% and 700% for the most important plastic pipe material HDPE (high-density polyethylene) according to the prior art. To reduce the effort for set-up operations when changing from one pipe dimension (diameter and wall thickness) to another, is It is of great benefit if the annular gap of the extrusion tool is optimized for as many product variants as possible. Especially if an adjustable calibration device is additionally used in the process, a large product window can be covered without plant stop and conversion work with such an optimized design of the extrusion tool. The above-mentioned design criteria are insufficient for this.
Aufgabe der vorliegenden Erfindung ist es daher, ein gattungsgemäßes Verfahren zur Verfügung zu stellen, welches mit Messwerten arbeitet, die eine optimale Fahrweise der Extrusionsanlage auch bei einem Dimensionswechsel gewährleisten. It is therefore an object of the present invention to provide a generic method which works with measured values which ensure an optimal mode of operation of the extrusion system even when changing the dimensions.
Diese Aufgabe wird erfindungsgemäß mit einem Verfahren gelöst, welches die Merkmale des Anspruchs 1 aufweist. This object is achieved by a method having the features of claim 1.
Erfindungsgemäß wird zwischen dem Extrusionswerkzeug und der Kalibriervorrichtung an mehreren Stellen exakt der Durchmesser, die Wandstärke, etwaige Formabweichungen und das Durchhängen des Schmelzeschlauches ermittelt. Damit können vier wesentliche Effekte in der Rohrextru- sion mit in die Auslegung des Extrusionswerkzeuges einbezogen werden, die bisher nicht berücksichtigt wurden. According to the invention, the diameter, the wall thickness, any shape deviations and the sagging of the melt tube are determined at several points between the extrusion tool and the calibration device. Thus, four major effects in pipe extrusion can be included in the design of the extrusion tool, which were previously not considered.
Einer dieser Effekte ist die Strangaufweitung der Schmelze nach dem Verlassen des Extrusionswerkzeuges. Im Extrusionswerkzeug wird das ge- schmolzene Kunststoffmaterial unter hohem Druck durch enge Kanäle und schließlich den Ringspalt am Austritt gepresst. Hierbei orientieren sich die freibeweglichen Makromoleküle des Kunststoffes in Extrusionsrichtung. Nach dem Verlassen des Extrusionswerkzeuges unterliegen die Makromoleküle keinem so großen äußeren Zwang mehr, so dass sie sich wieder zusammen- ziehen und zu einem Aufweiten des Durchmessers und einer Vergrößerung der Wandstärke des Schmelzeschlauches führen. Ein weiterer Effekt ist das Durchhängen des weichen Schmelzeschlauches zwischen Extrusionswerkzeug und Kalibriervorrichtung, dem bei großen Rohrdurchmessern mit einem Höhenversatz zwischen Extrusionswerkzeug und Kalibriervorrichtung entgegengewirkt werden muss. One of these effects is the strand expansion of the melt after leaving the extrusion die. In the extrusion die, the molten plastic material is forced under high pressure through narrow channels and finally the annular gap at the outlet. In this case, the freely movable macromolecules of the plastic are oriented in the extrusion direction. After leaving the extrusion die, the macromolecules are no longer subject to such great external constraint that they contract again and lead to an expansion of the diameter and an increase in the wall thickness of the melt tube. Another effect is the sagging of the soft melt tube between the extrusion die and the calibration device, which must be counteracted with large pipe diameters with a height offset between the extrusion die and the calibration device.
Schließlich ist ein weiterer Effekt das sogenannte Sagging, das Fließen von heißem, fließfähigem Kunststoffmaterial von der Oberseite des Schmelzeschlauches zu dessen Unterseite. Finally, another effect is the so-called sagging, the flow of hot, flowable plastic material from the top of the molten tube to its bottom.
Darüber hinaus können diese Messdaten für eine optimale Zentrierung von Düse und Dorn des Extrusionswerkzeuges sowie zum Einstellen eines optimalen Einlaufwinkels des Schmelzeschlauchs in die Kalibiervorrichtung genutzt werden. In addition, these measurement data can be used for optimum centering of the nozzle and mandrel of the extrusion tool as well as for setting an optimal inlet angle of the molten tube into the calibration device.
In vorteilhafter Ausgestaltung der Erfindung wird zur Erfassung der Messdaten die optische oder vollelektronische Terahertz- oder Gigahertz- Messtechnik eingesetzt. Da diese Art der Messtechnik berührungslos und ohne Koppelmedium arbeitet, kann eine Messung auch an heißen, berüh- rungsempfindlichen Körpern, wie einem Schmelzeschlauch direkt nach dem Extrusionswerkzeug in der Rohrextrusion erfolgen. In an advantageous embodiment of the invention, optical or fully electronic terahertz or gigahertz measuring technology is used to acquire the measured data. Since this type of measurement technique operates without contact and without coupling medium, a measurement can also be made on hot, contact-sensitive bodies, such as a molten tube, directly after the extrusion tool in the tube extrusion.
Ordnet man Gigahertz- oder Terahertz-Sensoren an mehreren Positionen des Umfangs des Schmelzeschlauchs direkt nach Austritt aus dem Extrusionswerkzeug und ebenso an mehreren Positionen des Umfangs unmittelbar vor dem Eintritt in die Kalibriervorrichtung an, so ermöglicht das: If one associates gigahertz or terahertz sensors at several positions of the circumference of the melt tube directly after exiting the extrusion die and also at several positions of the circumference immediately before entry into the calibration device, this allows:
- die Vermessung der Abstände zwischen den Sensoren und dem the measurement of the distances between the sensors and the
Schmelzeschlauch und damit die Berechnung des Durchmessers der Schmelzvorlage und des Durchhängens des Schmelzeschlauches - die Vermessung der Wandstärken des Schmelzeschlauchs an den Sensorpositionen und, über die die Unterschiede auf dem Umfang, die Exzentrizität der Wandstärke Melt tube and thus the calculation of the diameter of the melt template and the sagging of the melt tube - Measuring the wall thicknesses of the melt tube at the sensor positions and, beyond the differences on the circumference, the eccentricity of the wall thickness
- durch Vergleich der Abstands-Messwerte nach dem Extrusionswerk- zeug und vor der Kalibriervorrichtung, die Berechnung der Einlaufwinkel des Schmelzeschlauchs in die Kalibriervorrichtung über den Umfang (bedingt durch die Schwerkraft ist der Einlaufwinkel an der Unterseite des Schmelzeschlauches immer anders als an der Oberseite) - by comparing the distance measured values after the extrusion tool and before the calibration device, the calculation of the inlet angle of the molten tube into the calibration device over the circumference (due to gravity, the inlet angle at the bottom of the molten tube is always different than at the top)
- durch Vergleich der Wandstärkenmesswerte nach dem Extrusions- werkzeug und vor der Kalibriervorrichtung, die Berechnung des Sagging der Kunststoffschmelze nach Austritt aus dem Extrusionswerk- zeug. - By comparing the wall thickness readings after the extrusion tool and before the calibration device, the calculation of sagging of the plastic melt after exiting the extrusion die.
Die Erfindung wird nachstehend anhand eines Ausführungsbeispiels her erläutert. In der dazugehörigen Zeichnung zeigt: The invention will be explained below with reference to an embodiment. In the accompanying drawing shows:
Fig. 1 eine Extrusionsanlage zur Herstellung von Kunststoffrohren mit ihren Hauptkomponenten in schematischer Darstellung, und Fig. 1 shows an extrusion plant for the production of plastic pipes with their main components in a schematic representation, and
Fig. 2 eine sehr schematische Darstellung eines sich zwischen dem Ausgang des Extrusionswerkzeuges und dem Einlauf der Kalibrierhülse ausbildenden Schmelzeschlauches. Fig. 2 is a very schematic representation of a forming between the output of the extrusion die and the inlet of the calibration sleeve melt tube.
Die in Figur 1 dargestellte Extrusionsanlage für Kunststoff röhre umfasst einen Extrudereinheit 1 mit einem Aufgabetrichter 2, über den der Extrudereinheit 1 ein thermoplastischer Kunststoff in Granulat- oder Pulverform zu- geführt wird. In der Extrudereinheit 1 wird das Granulat bzw. das Pulver er- wärmt, geknetet und plastifiziert. Anschließend wird der Kunststoff als formbare Masse in ein Extrusionswerkzeug 3 gefördert und dort durch einen Ringspalt 1 1 gedrückt. Der dadurch gebildete heiße, noch verformbare Schmelzeschlauch 4' läuft mit Übermaß in eine Kalibriervorrichtung 6 ein, die einen Vakuumtank 7 mit einer an dessen Eingang angeordneten, perforierten Kalibrierhülse 8 aufweist. Die Kalibrierhülse 8 ist stufenlos im Durchmesser einstellbar, so dass das extrudierte Rohr 4 auf den gewünschten Außendurchmesser fixiert werden kann. Nach dem Verlassen der Kalibriervorrichtung 6 tritt das Rohr 4 in eine Kühlstrecke 9 ein, in der es auf etwa Raumtem- peratur abgekühlt wird. Am Ende der Extrusionslinie ist eine Säge 10 angeordnet, in der das extrudierte Rohr 4 auf eine vorgegebene Länge abgelängt wird. Das produzierte Rohr 4 wird mittels einer Abzugseinheit 5 durch die vorgelagerten Einrichtungen der Extrusionsanlage gezogen. Wie aus Figur 2 hervorgeht, läuft der aus dem zwischen einer Düse 12 und einem Dorn 13 des Extrusionswerkzeuges 3 gebildete Ringspalt 1 1 austretende Schmelzeschlauch 4' mit Übermaß in die Kalibrierhülse 8 der Kalibriervorrichtung 6 ein. Unmittelbar nach Austritt aus dem Extrusionswerkzeug 3 und unmittelbar vor dem Eintritt in die Kalibrierhülse 8 die Kalibrier-vorrich- tung 6 sind auf dem Umfang des Schmelzeschlauches 4' verteilt mehrere Gigahertz- oder Terahertz-Sensoren 14 angeordnet. Mittels dieser Sensoren 14 werden die Geometriedaten des Schmelzeschlauches 4' ermittelt. So werden die Abstände zwischen den Sensoren 14 und dem Schmelzeschlauch 4' vermessen, woraus sich der Durchmesser des Schmelzeschlauches 4' und sein Durchhängen berechnen lässt. Weiterhin wird die Wandstärke des Schmelzeschlauches 4' an den Positionen der Sensoren 14 vermessen, und aus den gemessenen Unterschieden über dem Umfang verteilt, die Exzentrizität der Wandstärke bestimmt. Ferner kann durch einen Vergleich der Abstands- messwerte der Sensoren 14 nach dem Extrusionswerkzeug 3 und vor der Kalibriervorrichtung 6 der Einlaufwinkel des Schmelzeschlauches 4' in die Kalibriervorrichtung 6 berechnet werden. Darüber hinaus kann durch einen Vergleich der Wandstärkenmesswerte nach dem Extrusionswerkzeug 3 und vor der Kalibriervorrichtung 6 das Sagging der Kunststoffschmelze nach dem Austritt aus dem Extrusionswerkzeug 3 berechnet werden. Die gewonnenen Messdaten bzw. die daraus berechneten Werte können auf vielfältige Weise zur Optimierung des Prozesses verwendet werden. Vorzugsweise indem die Messdaten mit geeigneten Algorithmen über die Anlagensteuerung entweder automatisch eine Korrektur der Steuergrößen vornehmen oder über eine geeignete grafische Benutzeroberfläche (GUI) dem Bediener detaillierte Einstellungsvorgaben vorschlagen. Hierbei sind die Messdaten und die korrelierenden Steuergrößen die folgenden: The extrusion line for plastic pipe shown in Figure 1 comprises an extruder unit 1 with a feed hopper 2, via which the extruder unit 1, a thermoplastic resin in granular or powder form is fed. In the extruder unit 1, the granulate or the powder is warms, kneads and plasticizes. Subsequently, the plastic is conveyed as a moldable material in an extrusion die 3 and pressed there through an annular gap 1 1. The thus formed, still deformable melt tube 4 'runs with oversize in a calibration device 6, which has a vacuum tank 7 with a arranged at the input, perforated Kalibrierhülse 8. The calibration sleeve 8 is infinitely adjustable in diameter, so that the extruded tube 4 can be fixed to the desired outer diameter. After leaving the calibration device 6, the tube 4 enters a cooling section 9, in which it is cooled to about room temperature. At the end of the extrusion line a saw 10 is arranged, in which the extruded tube 4 is cut to a predetermined length. The produced pipe 4 is pulled by means of a take-off unit 5 through the upstream facilities of the extrusion plant. As can be seen from FIG. 2, the melt tube 4 'emerging from the annular gap 1 1 formed between a nozzle 12 and a mandrel 13 of the extrusion die 3 passes into the calibration sleeve 8 of the calibrating device 6 with an oversize. Immediately after exiting the extrusion die 3 and immediately before entering the calibration sleeve 8, the calibration device 6 has a plurality of gigahertz or terahertz sensors 14 distributed over the circumference of the melt tube 4 '. By means of these sensors 14, the geometric data of the molten tube 4 'are determined. Thus, the distances between the sensors 14 and the molten tube 4 'are measured, from which the diameter of the molten tube 4' and its sagging can be calculated. Furthermore, the wall thickness of the melt tube 4 'is measured at the positions of the sensors 14, and distributed from the measured differences over the circumference, determines the eccentricity of the wall thickness. Furthermore, the inlet angle of the molten tube 4 'into the calibrating device 6 can be calculated by comparing the distance measured values of the sensors 14 after the extrusion die 3 and before the calibrating device 6. In addition, through a Comparison of the wall thickness measured values after the extrusion die 3 and before the calibration device 6, the sagging of the plastic melt after the exit from the extrusion die 3 are calculated. The measured data obtained or the values calculated therefrom can be used in a variety of ways to optimize the process. Preferably, by the measurement data with suitable algorithms via the plant control either automatically make a correction of the control variables or suggest a detailed graphical user interface (GUI) the operator detailed settings. Here, the measured data and the correlating control variables are the following:
Messwert Exzentrizität Steuergröße Zentrierschrauben des Measured value Eccentricity Control value Centering screws of the
Extrusionswerkzeuges Temperaturzonen des Extrusionswerkzeuges (bei thermischer Rohrkopfzentrierung)  Extrusion tool Temperature zones of the extrusion tool (for thermal tube head centering)
Messwert Durchhängen Steuergröße Höhenversatz zwischen Measured value sagging control height height offset between
Extrusionswerkzeug und Kalibriervorrichtung  Extrusion tool and calibration device
Messwert Einlaufwinkel Steuergröße Abstand zwischen Extrusionswerkzeug und Kalibriervorrichtung Measured value Inlet angle Control variable Distance between extrusion tool and calibration device
Weiterhin können die gewonnenen Messdaten auch zur Optimierung der Auslegung des Extrusionswerkzeuges 3, speziell zur Berechnung der optimalen Ringspaltgeometrie für einen breiten Einsatzbereich genutzt werden. Hier können im Besonderen anstelle der Abmessungen des Ringspaltes 1 1 des Extrusionswerkzeuges 3 die tatsächlich gemessenen Durchmesser und Wandstärken des durch die Strangaufweitung vergrößerten Schmelzeschlauches 4' in die Auslegung einfließen. Furthermore, the measured data obtained can also be used to optimize the design of the extrusion tool 3, especially for calculating the optimum annular gap geometry for a wide range of applications. Here, in particular instead of the dimensions of the annular gap 1 1 of the extrusion die 3, the actual measured diameter and wall thickness of the enlarged by the strand expansion melt tube 4 'incorporated into the interpretation.

Claims

Patentansprüche claims
1 . Verfahren zur Regelung und Steuerung von Rohrextrusionsanlagen unter Einbeziehung von Messdaten eines produzierten Rohres (4), wobei ein aus einem Ringspalt (1 1 ) einer Extrudereinheit (1 ) austretender Schmelzeschlauch (4') mit Übermaß in eine nachfolgende Kalibriervorrichtung (6) einläuft, dadurch gekennzeichnet, dass zwischen Extrusionswerkzeug (3) und Kalibriervorrichtung (6) an mehreren Stellen exakt der Durchmesser, die Wandstärke, etwaige Formab- weichungen, die Ovalität und das Durchhängen des Schmelzeschlauches (4') ermittelt wird, und diese Messwerte bzw. daraus berechnete Daten zur Regelung und Steuerung der Extrusionsanlage herangezogen werden. 2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die1 . Method for the regulation and control of pipe extrusion plants including measurement data of a produced pipe (4), wherein one of an annular gap (1 1) of an extruder unit (1) exiting melt tube (4 ') with excess passes into a subsequent calibration device (6), characterized in that exactly the diameter, the wall thickness, any shape deviations, the ovality and the sagging of the melt tube (4 ') are determined at several points between the extrusion die (3) and the calibration device (6), and these measured values or data calculated therefrom used for controlling and controlling the extrusion plant. 2. The method according to claim 1, characterized in that the
Messdaten berührungslos erfasst werden. Measurement data are recorded without contact.
Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass dieA method according to claim 2, characterized in that the
Messdaten mittels optischer oder vollelektronischer Messtechnik Giga- oder Terahertz-Bereich erfasst werden. Measurement data can be recorded by means of optical or fully electronic measurement technology Gigahertz or terahertz range.
Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die Messdaten und die daraus berechneten Daten für eine automatische kontinuierliche Ansteuerung der Extrusionsanlage Abstand Extrusionswerkzeug (3) zur Kalibriervorrichtung (6), Höhenversatz Extrusionswerkzeug (3) zur Kalibriervorrichtung (6), Zentrierung Düse (12) zu Dorn (13)) genutzt werden. Method according to one of the preceding claims, characterized in that the measured data and the data calculated therefrom for automatic continuous control of the extrusion system distance extrusion tool (3) to the calibration device (6), height offset extrusion tool (3) to the calibration device (6), centering nozzle ( 12) to thorn (13)) are used.
5. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die Ansteuerung der Extrusionsanlage anhand der Messdaten und der daraus berechneten Daten durch eine detaillierte Benutzerführung über eine geeignete grafische Benutzeroberfläche (GUI) erfolgt. 5. The method according to any one of the preceding claims, characterized in that the control of the extrusion plant based The measured data and the data calculated therefrom are performed by a detailed user guidance via a suitable graphical user interface (GUI).
Anordnung zur Durchführung des Verfahrens nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass zur Erfassung der Messdaten mehrere Sensoren (14) unmittelbar nach dem Austritt des Schmelzeschlauches (4') aus dem Extrusionswerkzeug (3) und unmittelbar vor seinem Eintritt in die Kalibriervorrichtung (6) jeweils auf den Umfang des Schmelzeschlauches (4') verteilt angeordnet sind. Arrangement for carrying out the method according to one of the preceding claims, characterized in that for detecting the measurement data a plurality of sensors (14) immediately after the outlet of the melt tube (4 ') from the extrusion die (3) and immediately before its entry into the calibration device (6 ) are distributed in each case on the circumference of the molten tube (4 ').
EP17728443.7A 2016-05-18 2017-05-17 Method and assembly for the open-loop and closed-loop control of pipe extrusion systems Withdrawn EP3458244A1 (en)

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DE102018104705B4 (en) 2018-03-01 2020-03-26 Sikora Ag Method and device for measuring a tubular strand
DE102018122391A1 (en) * 2018-09-13 2020-03-19 Sikora Ag Device and method for detecting an object
DE102018126192A1 (en) * 2018-10-22 2020-04-23 INOEX GmbH Innovationen und Ausrüstungen für die Extrusionstechnik Method and device for determining and regulating the entry angle of a melt hose into a calibration sleeve
DE102019119491B4 (en) 2019-07-18 2021-10-07 Sikora Ag Method and device for measuring a tubular strand
CN112815841B (en) * 2021-01-04 2022-08-09 中国航空制造技术研究院 Position calibration method and device for normal measurement sensor

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AT401031B (en) * 1988-11-18 1996-05-28 Cincinnati Milacron Austria DEVICE FOR REGULATING THE WALL THICKNESS
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