DE102005047285B4 - Method for guiding a PLC controlled and equipped with a profile temperature control and press speed control extruder for metals - Google Patents

Abstract

Method for guiding an SPS-controlled extrusion press for metals equipped with a profile temperature control and press speed control,
In which a prescribed by the operator setpoint to the oil flow rate and / or pressing speed in conjunction with preset in the PLC for the press guide parameters and recorded profiles of profile temperature, pressing force and axial Barrentemperaturprofils, for process control and for determining and specifying gradients of the setpoints for Barentemperatur- In order to determine the quality and dimensional stability of the pressed product, characteristics of the surface condition and the dimensions of the profile are recorded with the aid of an image processing system and to determine whether the Quality of the product specified ne requirements met, one. technical diagnostic system is used,
- And at the beginning of each cycle k + 1, the oil flow rate and / or. Press speed and the axial bar temperature profile of the material to be pressed on the basis of a calculation model, ...

Description

This The invention relates to a method for guiding a PLC controlled and with a profile temperature control and press speed control equipped extruder for metals

State of the art

extrude are commonly used for making stranded products made of metal, glass or plastic. When extruding from Metals, such as B. of aluminum, which in the following In particular, aluminum bars are placed in an oven at 400 to 500 ° C heated and then loaded into a receptacle (recipient). This one-sided by a die closed, the breakthrough of the cross section of the resulting profile strand corresponds. From the other side is with a stamp under the influence of a very large force (> 10 MN) the block except for a small one Rest pushed through the die. After completion of a cycle, a new block is loaded and the Pressing process can be repeated.

In this process, in order to maximize productivity and homogenize product quality, it is desirable to control the thermal budget, taking into account the mechanical boundary conditions. If x and l represent the (expressed) length of the ingot or the path that the ram has traveled since the start of the pressing cycle in one cycle, then the temperature θ _P (l) of the protruding profiles is determined by the preheating temperature of the ingots θ _B (x), o <x <l, and the pressing speed v _press (x), o <x <l. Thus, in order to obtain a certain predetermined desired profile, the profile temperature at the exit of the die (also referred to as 'strand exit temperature') θ _P (l), the pressing speed v _press (l) and the bar temperature θ _B (l), 0 <l <= L, L = length of the billet, run suitably.

The press speed v _press (l) in turn is set in modern systems by specifying a desired course v _{press soll} (l) (usually a constant) by the surgeon or by a parent program. A speed control ensures that the actual press speed v _press (l) is equal to the desired press speed v _{press soll} (l) specified by the superordinated program or by the operator, if the _press force F _press remains within its limits. In general, the speed control is implemented with a programmable logic controller (PLC) memory. In older systems, the press speed v _{press is} only implicitly specified by the operator input for the adjustment of the oil flow rate of the hydraulic system. The operator input is the setpoint for the swivel angle of a swivel angle pump or for the valve position. Depending on which of the variables is manipulated, in the following u (l) denotes the pressing speed or the swivel angle or the valve position.

As well as the pressing speed, the actual axial temperature profile of the bar temperature 'bar temperature profile' θ _B (l) is achieved by prescribing a temperature profile θ _{B soll} (l) to the temperature control of the bar furnace or the quench system. In WO 2005/03515771 such a method is described.

In addition to the press speed and barrel temperature control, it is desirable to maintain the temperature θ _P (l) of the emergent aluminum profile at a constant predetermined value by using noncontact temperature sensing devices and control to accomplish the so-called isothermal extrusion process. In this case, depending on the desired constant outlet temperature θ _P and the measured axial temperature profile θ _B (l) of the billet to be pressed, the press speed profile v _{press soll} (l) is determined and predetermined. In DE 693 25 367 T2 such a method is described.

If you want to minimize the press time per cycle while achieving given profile and material properties, without violating the force limits on the press and die, then you must set the optimum values for the profile _{exit temperature} θ _{POp t} and the press _speed v _pressOpt and the associated Course of the bar temperature setpoint course θ _{BShould correspond} to the required product properties, exactly determine in advance and this by specifying the associated desired curves v _{press soll} (l) = v _pressOpt and θ _PSoll = θ _POpt and θ _{B soll} (l) and use of appropriate controls during of pressing. However, such a provision is not realistic in practice, since it requires the consideration of elusive influencing factors such as material composition, profile geometry, matrix design, etc.

In the practice supports the process engineer usually relies on his experience the values for the Bar temperature and pressing speed are fixed in advance and transmitted this the surgeon. The surgeon sets accordingly the setpoints - usually as a constant over the whole cycle - for the bar temperature and the press speed control loops. The profile exit temperature is rarely noticed.

A recent development in the field of extrusion represents the profile temperature control used in a few modern plants in the industry Press operation is used. For such a control, which is usually realized with the press speed as a manipulated variable, three methods are known: a) the simulated isothermal extrusion, b) controlled isothermal extrusion and c) the cyclic control of extruders. Process c), which has been successfully tested and used in modern extruders with memory programmable control systems (SPS) and cruise control, is described in the European patent EP 0615 795 B1 specified for the cyclic control of extruders. In older systems, a speed control is not available, the input via a rotary knob, with which the operator specifies the desired angular position for the swivel angle or valves of the hydraulic system. For such facilities is in DE 101 23 274 B4 a method for the control of the outlet temperature θ _P (l) specified.

The known control method for the pressing speed or profile temperature assume that the values or the courses the process variables that when pressing should be respected, as well as the limits, within which these should be, determined by the process engineer in advance be handed over to the surgeon. This happens often Not. In addition, the surgeon is usually overwhelmed when he set the target value for the Profile temperature and the limits for the press speed and select bar temperature after a die change and should set.

This does not lead seldom that the installed automation is not used at all becomes. The aim of the patent is to change this situation by be specified, which accomplish that the automation system with only the usual Starting from the operator set sizes, the process is transferred to the optimal operating point without the surgeon additional Must make adjustments.

task

• I. Automatische Optimierung durch iterative Barrentemperatursenkung
• II. Automatische Optimierung mit einem differentiellem Prozessmodell

Object of the present invention is for extrusion presses equipped with Pressgeschwindigkeits-, Profilaustrittstemperatur- and Barentemperaturregelungen to specify methods with which the optimal process control is accomplished automatically, the handles of the press operator remain the same as in a press without automation is solved Task by a method having the features according to claim 1. The optimization of the extrusion process is carried out by

• I. Automatic optimization by iterative bar temperature reduction
• II. Automatic optimization with a differential process model

How the automatic works Process optimization method

The proposed method works after a learning phase, the after Each die change takes place in two phases, the cyclical expire consecutively.

After each die change, the operator's experience is started: At the beginning of the first cycle, the surgeon sets the bar temperature θ _B0 (l) and the input (usually the press _speed ) u _soll0 (l) = u ₀ or v _Ppress0 one. After the first cycle has elapsed, first the evaluation of the courses of the measured input _quantity u ₁ (l) (and possibly additionally the _{pressing speed} v _Ppress (l)), the output θ _P1 (l), the bar temperature θ _B1 (l) and the Press force F ₁ (l) determines the parameters of the mathematical calculation model in the optimization computer. In addition, the magnitudes max {θ _P1 (l)) and max {v _Ppress1 (l)} are determined. The setpoint θ _Psoll for the profile _{temperature control} is set equal to max {θ _P1 (l)}. The permissible limits for the input are determined as a function of max {v _Ppress1 (l)), which should be equal to v _{Ppress0 in} the case of a well-functioning press _{speed control} .

The regulation of the profile _{outlet temperature} to the value θ _Psoll then starts from the second cycle on the _{pressing speed} as a manipulated variable.

In the k-th cycle, k ≥ 2, with the aid of a differential calculation model, the measured temperatures of the bar temperatures θ _Bk (t) and θ _{Bk + 1} (t), the exit temperature θ _Pk (t) and the operator input u _k (t ) determines the course of the operator input size u _{k + 1} (t) such that the control error e k + 1 (t) = θ psetpoint (t) - θ Pk + 1 (t) (1) is as small as possible, whereby the control effort u _{k + 1} (t), in particular with respect to manipulated variable limitations F _{Press max} , U _max and U _{min is} taken into account. The setpoint of the bar temperature is initially not changed. Where necessary, the parameters of the differential calculation model are adjusted. The differential calculation model provides a linear link between changes in the process variables with respect to working trajectories and is robust in the application.

• • (nach Verfahren I) die Barrentemperatur um einen bestimmten Betrag gesenkt bzw.
• • (nach Verfahren II) ein neuer Sollwertverlauf für die Barrentemperatur berechnet und vorgegeben.

After leveling off the profile temperature control (ie when the control error becomes small enough) or after expiration of a certain number i (eg i = 3) of cycles, becomes

• • (according to method I) the bar temperature is lowered by a certain amount or
• • (according to method II) a new setpoint curve for the bar temperature is calculated and specified.

In the subsequent cycles, the profile temperature θ _Pk (x) is further controlled by the input quantity u _k (l), which in most cases also represents the pressing speed curve v _k (l). The average profile speed increases, provided that the pressing force is not too long an interval at its upper limit. If this is not the case, the bar temperature reduction is reversed.

To Each press cycle checks the product quality using a diagnostic procedure. deteriorated the product quality, so the barrel temperature reduction is also reversed.

• 1. Mess- und Regelungssystem für die Pressgeschwindigkeit (bzw. Öldurchflussmenge/Ventilstellung der Hydraulik).
• 2. Mess- und Regelungssystem für die Profilaustrittstemperatur
• 3. Mess- und Regelungssystem für die Barrentemperatur
• 4. Mess- und Diagnosesystem für die Profilqualität
• 5. Übergeordnete Optimierungsrechner.

For the realization of the processes, the extrusion press is supplemented by the following measurement and control functionalities or components, if they are not already present (Figure 1):

• 1. Measuring and control system for the pressing speed (or oil flow rate / valve position of the hydraulic system).
• 2. Measurement and control system for the profile outlet temperature
• 3. Measurement and control system for the bar temperature
• 4. Profile Quality Measurement and Diagnostic System
• 5. Higher-level optimization calculator.

• 1. Mess- und Regelungssystem für die Pressgeschwindigkeit (bzw. Öldurchflussmenge/Ventilstellung der Hydraulik) Dieses stellt die Einrichtung für die Operatoreingabe dar und wird in den meisten Fällen vorhanden sein. Es wird die Stempelgeschwindigkeit bzw. die Öldurchflussmenge/Ventilstellung der Hydraulik gemessen und mit dem vom Operateur bzw. von der übergeordneten Regelung vorgegebenen Sollwert u_soll verglichen und geregelt.
• 2. Mess- und Regelungssystem für die Profilaustrittstemperatur Die Profilaustrittstemperatur wird mit einem berührungslosen Pyrometer gemessen und mit Hilfe eines Regelungsverfahrens, wie z. B. mit Hilfe des im Europäischen Patent EP 0615 795 B1 angegebenen Verfahrens, geregelt.
• 3. Mess- und Regelungssystem für die Barrentemperatur Die Temperatur der Barren, die meist in einem Gas oder Induktionsofen geheizt werden und eventuell mit einem Quenchsystem abgekühlt werden, ist unmittelbar vor dem Laden in den Rezipienten zu messen. U. U. steht ein regelbarer Barrenofen zur Verfügung, mit welchem dem Barren ein vorgegebenes axiales Temperaturprofil, genannt Taper, aufgeprägt werden kann. In solchen Systemen wird durch Aufbringung des optimalen Tapers iso-thermes Pressen bei konstanter Geschwindigkeit erzielt. Üblicherweise wird der Sollverlauf spezifiziert durch die Kopftemperatur und den 'Taper', d. h. die Differenz zwischen der Kopftemperatur und der Temperatur am hinteren Ende des Barrens. In älteren Anlagen dagegen ist es nur möglich einen konstanten Sollverlauf vorzugeben.
• 4. Mess- und Diagnosesystem für die Profilqualitätserfassung Dieses besteht aus einem Bildverarbeitungssystem, das Merkmale der Profiloberfläche wie Oberflächenrauheit, Riefentexturen, Blasen etc. sowie die Maßhaltigkeit des Produkts on-line überwacht. Um die Überwachung zu realisieren, werden die Merkmale und die Maßhaltigkeit durch geeignete Zahlen dargestellt und zu einem Merkmalsvektor zusammengefasst. Ein Klassifikationsverfahren wird verwendet, um die Verknüpfung zwischen dem Merkmalsvektor und dem Ausgangssignal, das die Güte des Produkts darstellt, zu realisieren. Zur Realisierung der Verknüpfung wird beispielsweise ein neuronales Netzwerk eingesetzt. Eine mögliche Anordnung der Bildverarbeitungssensoren, die beispielsweise aus Zeilenkameras bestehen können, zeigt Bild 2.
• 5. Übergeordnete Optimierungsrechner Aufgabe des übergeordneten Optimierungsrechners ist es, Sollwertverläufe für die Regelung der Pressgeschwindigkeit (bzw. Öldurchflussmenge/Ventilstellung der Hydraulik) und des Barrenofens zu erzeugen, die unter Berücksichtigung der zulässigen Grenzen der Prozessgrößen sowie der Produktqualität die Presszeit zu einem Minimum machen.

These serve to realize the following functions

• 1. Press speed measuring and control system (or oil flow rate / hydraulic valve position) This is the operator input device and will be present in most cases. It is the punch speed or the oil flow rate / valve position of the hydraulics measured and compared with the set by the surgeon or from the higher-level control setpoint u _should and compared.
• 2. Measurement and control system for the profile outlet temperature The profile outlet temperature is measured with a non-contact pyrometer and with the aid of a control method, such. B. by means of the European patent EP 0615 795 B1 specified method, regulated.
• 3. Bar temperature measuring and control system The temperature of the bars, which are usually heated in a gas or induction oven and may be cooled with a quench system, must be measured immediately before loading into the recipient. In some cases a controllable bar-type oven is available with which a predetermined axial temperature profile, called Taper, can be applied to the bar. In such systems, by applying the optimum tapper, iso-thermal pressing is achieved at a constant speed. Usually, the target profile is specified by the head temperature and the taper, ie the difference between the head temperature and the temperature at the rear end of the billet. In older systems, however, it is only possible to specify a constant setpoint course.
• 4. Profile Quality Measurement and Diagnostic System This consists of an image processing system that monitors features of the profile surface such as surface roughness, groove textures, bubbles etc. as well as the dimensional stability of the product on-line. To realize the monitoring, the features and the dimensional accuracy are represented by suitable numbers and combined into a feature vector. A classification method is used to realize the association between the feature vector and the output representing the quality of the product. To implement the link, for example, a neural network is used. A possible arrangement of the image processing sensors, which may consist of line scan cameras, for example, is shown in FIG. 2.
• 5. Higher-level optimization computers The purpose of the higher-level optimization computer is to generate setpoint curves for the control of the press speed (or oil flow rate / valve position of the hydraulics) and the bar furnace, which, taking into account the permissible limits of the process variables as well as the product quality, make the pressing time to a minimum.

It is taken into account, that u. U. a controllable Barrenofen / quench with several cooling water nozzles for disposal stands with which / which the bar a predetermined axial temperature profile, called Taper, imprinted can be. In such systems, by applying the optimal Tapers achieves iso-thermal pressing at a constant speed.

Method I: Automatic optimization by iterative bar temperature reduction

• a) Zu Beginn einer neuen Charge, stellt der Pressenführer die Eingangsgröße, nämlich die Pressgeschwindigkeit (bzw. den Öldurchfluss), auf den Wert u_soll, den er nach seiner Erfahrung für geeignet hält, ein. Falls es die Möglichkeit zur Tapereinstellung gibt, so stellt er ebenfalls anhand seiner Erfahrung die Sollwerte für die Barrentemperatur am Kopfende θ_B (0) und den Taper, d. h. die Temperaturdifferenz Δθ_B = θ_B(0) – θ_B(L) ein. Im Barrentemperaturofen werden demgemäß die Barren auf das axiale Temperaturprofil θ_B(l)= θ_B(0) – (l/L)Δθ_B geheizt.
• b) In der SPS werden die Grenzen u_min und u_max für die Eingangsgröße gemäß umin:= α1·usoll, α1 < 1, z. B. α1 = 0,95 umax:= α2·usoll, α2 > 1, z. B. α2 = 1,05festgelegt und dem Optimierungsrechner übergeben. Ebenso werden die Defaultwerte für die maximale Profilaustrittstemperatur sowie die maximale zulässige Presskraft und die Grenzen der Barrentemperatur, die im Speicher der SPS abgelegt sind, dem Optimierungsrechner als zulässige Grenzwerte θ_Pmax, F_{Press max} θ_Bmax, θ_Bmin, für die Modellrechnung übergeben.
• c) Vor Beginn des k = 1 ten Presszyklus werden die tatsächliche Barrentemperatur θ_B(l) gemessen und die Messwerte dem Optimierungsrechner zugeführt.
• d) Der k-te, k = 1, 2, 3, ... Presszyklus wird durchgeführt. Alle relevanten Prozessgrößen werden während der Pressung gemessen. Auch werden anhand von Temperatur- und Bildsensoren Merkmale der Profiloberfläche (Qualitätsparameter) erfasst. Am Ende des Zyklus wird mit Hilfe eines Diagnoseverfahrens überprüft, ob die Qualitäts-parameter im Toleranzbereich liegen: • Ist dies der Fall, so wird das vorliegende zulässige Maximum der Profilaustrittstemperatur für die Modellrechnung anhand eines einfachen Modells durch das Maximum des gemessenen Verlaufs der Profilaustrittstemperatur ersetzt. Die zulässige obere Grenze der Eingangsgröße wird ersetzt durch die Grenze u_max gemäß umax:= α2·umax gemessen., α2 > 1, z. B. α2 = 1,05 wobei u_{max gemessen} das Maximum des gemessenen Verlaufs der Eingangsgröße darstellt.
• • Ist dies nicht der fall, so wird das vorliegende zulässige Maximum der Profilaustrittstemperatur zurückgesetzt auf den Wert, der vor der letzten Erhöhung vorlag. Die zulässigen Grenzen der Eingangsgrößen werden ebenfalls zurückgesetzt. Ferner werden die Parameter des einfachen Berechnungsmodells anhand der im vergangenen Zyklus akquirierten Messwerte nachgestellt.
• e) Vor Beginn der nachfolgenden (k + 1)-ten Pressung wird die Barrentemperatur gemessen. Im Optimierungsrechner wird anhand des einfachen Berechnungsmodells der Verlauf für die Eingangsgröße (nämlich die Pressgeschwindigkeit bzw. Öldurchfluss) für den Zyklus derart berechnet, dass die Prozessgrößen in ihren Grenzen bleiben und zugleich die Presszeit minimal ist.
• f) Die weiteren Operationen der zweiten Pressung werden gemäß d) und e) durchgeführt. Nach einem jeden vielfachen einer gewissen einstellbaren Anzahl i (z. B. i = 3) von Zyklen werden statt der Operationen unter d) und e) die folgenden Operationen der Barrentemperaturabsenkung durchgeführt:
• d') Der k-te, k = 1, 2, 3, ... Presszyklus wird durchgeführt. Alle relevanten Prozessgrößen werden während der Pressung gemessen. Merkmale der Profiloberfläche (Qualitätsparameter) werden erfasst. Am Ende des Zyklus wird überprüft, ob die Geschwindigkeits- und Temperaturregelungen eingeschwungen sind und ob die Qualitäts-parameter im Toleranzbereich liegen. Es wird überprüft, dass genügend Presskraftreserve vorhanden ist. Ist dies der Fall, so wird der Barrentemperatursollwert um einen bestimmten Betrag abgesenkt und die Grenzen der Eingangsgröße (nämlich die Pressgeschwindigkeit bzw. Öldurchfluss) und der Profiltemperatur um geeignete Beträge erhöht. Die nachfolgenden Zyklen werden mit diesen Einstellungen durchgefahren.
• e') Am Ende des Zyklus, in dem ein Barren mit der neuen Barrentemperatur gepresst wurde, wird überprüft, ob a) die Presszeit sich erhöht hat und ob b) die Presskraft, Pressgeschwindigkeit und die Profiltemperatur in ihren Grenzen lagen. Mit Hilfe eines Diagnoseverfahrens wird überprüft, ob c) die Qualitätsparameter im Toleranzbereich liegen. Anhand der Ergebnisse der Überprüfungen wird, falls erforderlich, die Barrentemperaturabsenkung wird rückgängig gemacht.

The essential steps are the following:

• a) At the beginning of a new batch, the press operator sets the input variable, namely the press speed (or the oil flow), to the value u _soll , which he considers suitable according to his experience. If there is the possibility of tapering, he also sets, based on his experience, the set point values for the bar temperature at the head end θ _B (0) and the taper, ie the temperature difference Δθ _B = θ _B (0) - θ _B (L). In the billet temperature furnace, the billets are thus on the axial temperature profile θ _B (l) = θ _B (0) - heated (l / L) Δθ _B.
• b) In the PLC, the limits are u _min and u _max for the input quantity according to u min : = α 1 · u should , α 1 <1, z. B. α 1 = 0.95 u Max : = α 2 · u should , α 2 > 1, z. B. α 2 = 1.05 and passed to the optimization computer. Likewise, the default values for the maximum profile exit temperature as well as the maximum permissible press force and the limits of the bar temperature, which are stored in the memory of the PLC, are transferred to the optimization _computer as permissible limit values θ _Pmax , F _{Press max} θ _Bmax , θ _Bmin , for the model calculation.
• c) Before the beginning of the k = 1 th pressing cycle, the actual ingot temperature θ _B (l) is measured and the measured values are fed to the optimization computer.
• d) The kth, k = 1, 2, 3, ... press cycle is performed. All relevant process variables are measured during the pressing process. Also, characteristics of the profile surface (quality parameters) are detected by means of temperature and image sensors. At the end of the cycle, a diagnostic procedure is used to check whether the quality parameters are within the tolerance range: • If this is the case, the present maximum permissible profile exit temperature for the model calculation is replaced by the maximum of the measured profile of the profile exit temperature using a simple model , The permissible upper limit of the input variable is replaced by the limit u _{max in} accordance with u Max : = α 2 · u max measured. , α 2 > 1, z. B. α 2 = 1.05 where u _{max measured represents} the maximum of the measured curve of the input variable.
• • If this is not the case, then the maximum permissible profile exit temperature will be reset to the value that existed before the last increase. The permissible limits of the input variables are also reset. Furthermore, the parameters of the simple calculation model are readjusted on the basis of the measured values acquired in the previous cycle.
• e) Before the beginning of the subsequent (k + 1) -th pressing, the bar temperature is measured. In the optimization calculator, the curve for the input variable (namely the pressing speed or oil flow) for the cycle is calculated on the basis of the simple calculation model such that the process variables remain within their limits and at the same time the pressing time is minimal.
• f) The further operations of the second pressing are carried out according to d) and e). After every multiple of a certain settable number i (eg, i = 3) of cycles, the following barrel temperature lowering operations are performed instead of the operations under d) and e):
• d ') The kth, k = 1, 2, 3, ... press cycle is performed. All relevant process variables are measured during the pressing process. Features of the profile surface (quality parameters) are recorded. At the end of the cycle, it is checked whether the speed and temperature controls have settled and whether the quality parameters are in the tolerance range. It is checked that there is enough press force reserve. If this is the case, the bar temperature set point is lowered by a certain amount and the limits of the input variable (namely the pressing speed or oil flow) and the profile temperature are increased by suitable amounts. The following cycles are run through with these settings.
• e ') At the end of the cycle in which a bar was pressed with the new bar temperature, it is checked whether a) the pressing time has increased and b) the pressing force, pressing speed and the profile temperature were within their limits. A diagnostic procedure is used to check whether c) the quality parameters are within the tolerance range. Based on the results of the checks, if necessary, the bar temperature reduction is reversed.

Method II optimization with process model

The Process goes through the steps a) to f) like o. a.

• d'') Der k-te, k = 1, 2, 3, ... Presszyklus wird durchgeführt. Alle relevanten Prozessgrößen werden während der Pressung gemessen. Merkmale der Profiloberfläche (Qualitätsparameter) werden erfasst. Am Ende des Zyklus wird überprüft, ob die Geschwindigkeits- und Temperaturregelungen eingeschwungen sind und ob die Qualitäts-parameter im Toleranzbereich liegen. Es wird überprüft, dass genügend Presskraftreserve vorhanden ist. Ist dies der Fall, so wird anhand des differentiellen Berechnungsmodells der Verlauf der Barrentemperatur bestimmt, dem die minimale Presszeit entspricht, wobei die Größen i) Profilaustrittstemperatur, ii) Barrentemperatur, iii) Pressgeschwindigkeit und iv) Presskraft in ihren zulässigen Grenzen bleiben. Der Verlauf der Barrentemperatur wird dem Barrenofen vorgegeben. Weiterhin werden die Parameter des differentiellen Modells anhand der akquirierten Messwerte nachgestellt. Die nachfolgenden Zyklen werden mit diesen Einstellungen durchgefahren.
• e'') Am Ende des Zyklus, in dem ein Barren mit der neuen Barrentemperatur gepresst wurde, wird überprüft, ob a) die Presszeit sich erhöht hat und ob b) die Presskraft, Pressgeschwindigkeit und die Profiltemperatur in ihren Grenzen lagen. Mit Hilfe eines Diagnoseverfahrens wird überprüft, ob c) die Qualitätsparameter im Toleranzbereich liegen. Anhand der Ergebnisse der Überprüfungen wird, falls erforderlich, die Barrentemperaturabsenkung wird rückgängig gemacht.

However, after every multiple of a certain adjustable number i (eg, i = 3) of cycles, instead of the operations under d) and e), the following steps d "and e" of the bar temperature lowering are performed:

• d '') The kth, k = 1, 2, 3, ... press cycle is performed. All relevant process variables are measured during the pressing process. Features of the profile surface (quality parameters) are recorded. At the end of the cycle, it is checked whether the speed and temperature controls have settled and whether the quality parameters are in the tolerance range. It is checked that there is enough press force reserve. If this is the case, then the course of the bar temperature, which corresponds to the minimum pressing time, is determined from the differential calculation model, whereby the variables i) profile exit temperature, ii) bar temperature, iii) pressing speed and iv) pressing force remain within their permissible limits. The course of the bar temperature is given to the bar oven. Furthermore, the parameters of the differential model are readjusted on the basis of the acquired measured values. The following cycles are run through with these settings.
• e '') At the end of the cycle in which a billet was pressed with the new bar temperature, it is checked whether a) the pressing time has increased and b) the pressing force, pressing speed and the profile temperature were within their limits. A diagnostic procedure is used to check whether c) the quality parameters are within the tolerance range. Based on the results of the checks, if necessary, the bar temperature reduction is reversed.

i

Zeitindex (diskret), Ortsindex

k

Zyklus

indices:

i

Time index (discrete), place index

k

cycle

Claims (9)

Method for guiding an SPS-controlled extrusion press for metals, equipped with a profile temperature control and press speed control, in which a setpoint for the oil flow rate and / or press speed specified by the operator in connection with parameters preset in the PLC for the press guide and detected profile temperature profiles, Pressing force and axial bar temperature profiles are used to process and to determine and set bar temperature setpoint curves, taking into account the quality of the profile pressed in the previous cycle and determining the quality and dimensional stability of the pressed product when determining optimum characteristics the surface texture and the dimensions of the profile are recorded using an image processing system and to decide whether the quality of the product meets predetermined requirements, a. technical diagnostic system is used, - and in the before the beginning of each cycle k + 1, the oil flow rate and / or. Pressing speed and the axial bar temperature profile of the material to be pressed on the basis of a calculation model, which reproduces the relationship between the process variables a) bar temperature, b) pressing speed, c) pressing force and d) profile temperature, so automatically determined and setpoint _curves u _{sollk + 1} (l) or . θ _{Bsollk + 1} (l) for the subordinate control loops, that the pressing time successively decreases from cycle to cycle until it reaches its minimum and the temperature θ _{Pk + 1} (I) of the profile at the exit from the die is as constant as possible and equal to a predetermined setpoint θ _Psoll , and at the same time the press speed and the bar temperature within allowable limits remain and the quality of the pressed profile given requirements met, which enter into the calculation model, the permissible limits of the press speed and the profile temperature, as well as due to the hydraulic and / or the material properties of the die pressing force limit. Method according to claim 1, characterized that while of each cycle measured the process variables and at the end of the cycle the calculation model is tracked. Method according to one of Claims 1 and 2, characterized in that the profile _temperature setpoint θ _{Psoll to be preset} by the operator is automatically selected as the maximum of the outlet temperature of a preceding cycle and the permissible limit of the input variables is _measured by _{μ max} = α ₁ · u _max , α ₁ > 1, in particular α ₁ 1.05 with u _{max measured} = the maximum of the measured input variable in the past cycle is determined, whereby it is ensured by the operator and / or a technical diagnostic system that the quality of the product meets predetermined requirements. Method according to one of claims 1 to 3, characterized in that the desired course of the bar temperature θ _{Bsollk + 1} (l) in the k + 1st cycle when meeting the requirements "deviation of the profile temperature control <predetermined error limit" and / or "number of completed press cycles since last change> predetermined number i of waiting cycles "is automatically lowered successively by a preset value, so that the regulation of the outlet temperature via the input function u _{k + 1} (l) engages and thereby the pressing speed is automatically increased, the operator or a technical To ensure that the quality of the product satisfies predetermined requirements and automatically detects whether the pressing force is too long at its upper limit due to low bar temperatures to reverse the lowering of the bar temperature θ _{Bsollk + 1} (l) Method according to one of claims 1 to 4, characterized in that the determined desired course of the axial bar temperature curve θ _{Bsollk + 1} (l) is automatically transmitted to a furnace temperature control and adjusted there. Method according to one of claims 1 to 5, characterized in that the course of the bar temperature θ _{Bsollk + 1} (l) is determined on the basis of an exact differential model, such that with the determined bar temperature θ _{Bsollk + 1} (l) at the _{pressing speed} ≤ maximum permissible pressing _{speed, the isothermal} pressing process with profile temperature = maximum permissible profile temperature results and the pressing force <the maximum permissible pressing force remains and the pressing time T _{Zyk assumes} its minimum. Method according to one of claims 1 to 4, characterized in that the optimum setpoint _{curves of} the input function u _{sollk + 1} (l) and the axial Barentemperatursollverlaufs θ _{Bsollk + 1} (l) are determined using algorithms of the iterative learning control. Method according to claim 1, characterized in the absence of measured process variables, in particular during pressing the first bar of a batch given by the surgeon Setpoints for the bar temperature and the input of the oil flow rate or press speed in connection with the process control parameters preset in the PLC, namely for the definition not available in the PLC standing limits and for the determination and specification of the optimal curves of the nominal values for the bar temperature and oil flow rates or Pressgeschwindigkeitsregelkreise be used. Method according to one of claims 1 to 8, characterized that after running the Pressures of a batch of a product that iteratively optimized Setpoint profiles be saved and on a repetition of the product automatically be retrieved and used.