EP0806256B1 - Method for controlling the material flow during the drawing of sheet metal parts and device for carrying out the method - Google Patents
Method for controlling the material flow during the drawing of sheet metal parts and device for carrying out the method Download PDFInfo
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- EP0806256B1 EP0806256B1 EP97107440A EP97107440A EP0806256B1 EP 0806256 B1 EP0806256 B1 EP 0806256B1 EP 97107440 A EP97107440 A EP 97107440A EP 97107440 A EP97107440 A EP 97107440A EP 0806256 B1 EP0806256 B1 EP 0806256B1
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- European Patent Office
- Prior art keywords
- friction force
- holding
- force
- control loop
- segment
- Prior art date
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D24/00—Special deep-drawing arrangements in, or in connection with, presses
- B21D24/04—Blank holders; Mounting means therefor
- B21D24/08—Pneumatically or hydraulically loaded blank holders
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D24/00—Special deep-drawing arrangements in, or in connection with, presses
- B21D24/10—Devices controlling or operating blank holders independently, or in conjunction with dies
- B21D24/14—Devices controlling or operating blank holders independently, or in conjunction with dies pneumatically or hydraulically
Definitions
- the invention relates to a method for Control of material flow when pulling sheet metal parts the preamble of claim 1 and a device for Implementation of the process according to the preamble of Claim 10.
- FIG. 1a shows a double-acting press for drawing regular sheet metal parts.
- the pressing device 1 shows a workpiece 2 (sheet metal) which is clamped between a drawing ring 3 and a hold-down device 4 and is acted upon by a drawing punch 5.
- the punch force is denoted by F S , the hold-down force by F N.
- the workpiece 2 is held on the drawn part flange 6 and formed over the drawn edge 7 in the drawn part wall 8 (frame).
- the material flow is next to the board shape and the Draw beads continue from the between hold-down 4 and Sheet 2 or between sheet 2 and drawing ring 3 acting friction affects.
- Fig. 1b shows the basic structure of a known single-acting Press device 9 as a single-acting press hydraulic pulling device 10 with hydraulic cylinders 11 and the pull ring 3 described for FIG. 1a, the Hold-down device 4 and the punch 5.
- a hold-down force sensor is indicated with reference number 13. This press can be used to pull irregular sheet metal parts equally be used.
- the hydraulic pulling devices 10 consisting of hydraulic cylinders 11 that can be individually controlled via servo valves, not shown, can introduce the hold-down forces F N directly into the hold-down device 4 via the piston rods 12 (see FIG. 1b) or indirectly via sleeves (not shown, for example, DE 41 12 656 A1).
- Control loops represent a significant improvement Forming parameters such as the flange edge inlet Stamp force or the fold height of the currently running Use the drawing process as a control variable.
- the punch force F S contains the forces of friction between sheet metal 2 and hold-down device 4 and the friction between drawing ring 3 and hold-down device 4. However, it also includes all other frictional forces and the forming forces, so that they are only of limited use as a control variable for controlling the material flow is. The experience gained with this confirms the criticism of the use of these variables as reference variables for material flow control.
- the invention has for its object the known To improve drawing methods and drawing devices and in particular a more precise recording of the drawing parameters and the associated To enable process flows.
- the Frictional force between sheet and hold-down or sheet and Drawing ring can be considered as a control variable.
- FIGS 1a, 1b show the known prior art
- Fig. 2 shows a schematic representation of a Pulling device with control device, where - as far as possible - the same parts with the same Reference numerals as to Fig. 1a, 1b are designated.
- a control circuit 21 is used for material flow control, which, using the hold-down force F N as a manipulated variable 22 of the hold-down force F N, allows the friction acting on the surface 23 of the hold-down device and / or the drawing ring 3 after a friction predetermined command variable 24 (friction force F R over the pull path s) to regulate (Fig. 2).
- the friction force F R is therefore measured via a friction force sensor 25, 25 ′, 25 ′′, which is preferably designed as a three-component piezo force measuring element 26, ie based on a piezoelectric effect.
- Such sensors 25 ', 25'' can in particular also be installed at predetermined positions on the hold-down device 4 and / or also on the drawing ring 3 (see the broken line in FIG. 2).
- the control loop shown in FIG. 2 reacts automatically the changes in the tribological system 40, i.e. he regulates automatically the changes with the friction force sensor 25 measured friction force, for example, by changes in the Lubricant quantity and type of lubricant, the sheet surface etc. are caused.
- a Press or tool device 20 required, the one Change of hold-down force 30 during the drawing process allowed. This is when using hydraulic die cushions in the Table of single-acting presses, as also shown in Fig. 1b shows possible.
- each cylinder 11th can be controlled via its own servo valve 29.
- the Servo valve 29 controls the oil flow and thus determines the pressure acting in the cylinder 11 and thus the pressure on the segment 27 prevailing hold-down force 30 Pressure measurement in the cylinder 11 or via one in the power flow arranged hold-down force sensor 25, 26 can be determined.
- the segment is therefore based on three-component piezo force measuring elements 26 from. These allow the measurement of one Frictional force 25 'and that acting on the segment 27 Hold-down force 30 Frictional force sensor in the holding-down device of the drawing tool applicable.
- a segmentation of the hold-down device can with a correspondingly "soft" elastic design.
- the friction force sensor in Corner areas where wrinkles are to be suppressed with coupled to a pleat height sensor known from the literature are, so that it is always guaranteed that the Hold-down force is at least so great that folds in the Flange can be avoided with certainty.
- control unit Computer 31 with analog / digital interface used.
- desired curve shape 32 of the Frictional force over the tappet travel as reference variable 24 be filed.
- the assigned value of the friction force be read out.
- This is the controller 35 as setpoint 36th given.
- the controller places a difference between Setpoint 36 and actual value 38 fixed, it generates an actuating signal 39, which is an actuator (servo valve 29) of Hydraulic circuit of the segment is supplied.
- the signal influences the control element in such a way that the actual value of the Frictional force changes so that the difference between the actual value 38 and setpoint 36 is minimized.
- the control loop reacts accordingly independently on changes in the friction between Hold-down device and sheet metal and between drawing ring and sheet metal, caused by changes in the type or quantity of lubricant on the sheet, changes in the sheet surface and by tool lock or the like (tribological Characteristics).
Description
Die Erfindung betrifft ein Verfahren zur Materialflußsteuerung beim Ziehen von Blechformteilen nach dem Oberbegriff des Anspruchs 1 sowie eine Vorrichtung zur Durchführung des Verfahrens nach dem Oberbegriff des Anspruchs 10. The invention relates to a method for Control of material flow when pulling sheet metal parts the preamble of claim 1 and a device for Implementation of the process according to the preamble of Claim 10.
Beim Ziehen von Blechformteilen unterscheidet man zwischen zweifachwirkenden Pressen mit Ziehstößel und Niederhalterstößel und einfachwirkenden Pressen mit Ziehstößel und Zieheinrichtung im Pressentisch. Die Zieheinrichtung kann auch mittels im Ziehwerkzeug angeordnete hydraulische oder pneumatische Zylinder realisiert werden. When drawing sheet metal parts, a distinction is made between double acting presses with ram and Hold-down ram and single-acting presses Drawing ram and drawing device in the press table. The Drawing device can also be arranged in the drawing tool hydraulic or pneumatic cylinders can be realized.
Zur Erläuterung des Standes der Technik zeigt Fig. 1a eine zweifachwirkende Presse zum Ziehen regelmäßiger Blechformteile. Dabei zeigt die Presseinrichtung 1 ein Werkstück 2 (Blech), welches zwischen einem Ziehring 3 und einem Niederhalter 4 eingespannt und von einem Ziehstempel 5 beaufschlagt ist. Die Stempelkraft ist mit FS, die Niederhalterkraft mit FN bezeichnet. Das Werkstück 2 wird am Ziehteilflansch 6 gehalten und über die Ziehkante 7 in der Ziehteil-Wandung 8 (Zarge) umgeformt. To illustrate the state of the art, FIG. 1a shows a double-acting press for drawing regular sheet metal parts. The pressing device 1 shows a workpiece 2 (sheet metal) which is clamped between a drawing ring 3 and a hold-down device 4 and is acted upon by a drawing punch 5. The punch force is denoted by F S , the hold-down force by F N. The workpiece 2 is held on the drawn part flange 6 and formed over the drawn edge 7 in the drawn part wall 8 (frame).
Beim Ziehen von nicht rotationssymmetrischen Blechformteilen kommt der Steuerung des Materialflusses eine große Bedeutung zu. Ist die Niederhalterkraft FN zu gering, so kann es im Flanschbereich 6 zu einer Faltenbildung erster Art zwischen Niederhalter 4 und Ziehring 3 kommen (Fig. 1a). When drawing non-rotationally symmetrical sheet metal parts, the control of the material flow is of great importance. If the hold-down force F N is too low, wrinkling of the first type between the hold-down device 4 and the drawing ring 3 can occur in the flange area 6 (FIG. 1a).
Aber auch dann, wenn die Niederhalterkraft FN über der Kraft liegt, die zur Unterdrückung von Falten erster Art erforderlich ist, kann es zu einem zu starken Einlauf von Umformgut über die Ziehkante 7 in die Ziehteilwandung (Zarge) 8 hinein kommen, so daß Unruhen und sogar Falten in der Ziehteilwandung 8 entstehen. Wird jedoch der Materialfluß unter dem Niederhalter 4 so stark behindert, daß zu wenig Umformgut über die Ziehkante 7 in die Ziehteilwandung 8 fließt, dann treten Reißer im Ziehteil 2 auf. But even if the hold-down force F N is greater than the force required to suppress folds of the first type, there may be an excessive inflow of material to be formed via the drawing edge 7 into the drawing part wall (frame) 8, so that unrest occurs and even wrinkles arise in the drawing part wall 8. However, if the flow of material under the holding-down device 4 is hindered so much that too little material to be formed flows over the drawing edge 7 into the drawing part wall 8, then tears occur in the drawing part 2.
Aus diesem Grund ist man bestrebt, den Materialfluß beim Tiefziehen so zu steuern, daß weder Falten noch Reißer im Ziehteil 2 auftreten. For this reason, efforts are made to ensure that the material flow in the To control deep drawing so that neither folds nor tears in the Draw part 2 occur.
Der Materialfluß wird neben der Platinenform und den Ziehsicken weiterhin von der zwischen Niederhalter 4 und Blech 2 beziehungsweise zwischen Blech 2 und Ziehring 3 wirkenden Reibung beeinflußt. The material flow is next to the board shape and the Draw beads continue from the between hold-down 4 and Sheet 2 or between sheet 2 and drawing ring 3 acting friction affects.
Fig. 1b zeigt vom Grundaufbau eine bekannte einfachwirkende Presseneinrichtung 9 als einfachwirkende Presse mit hydraulischer Zieheinrichtung 10 mit Hydraulikzylindern 11 sowie den zu Fig. 1a beschriebenen Ziehring 3, dem Niederhalter 4 und dem Ziehstempel 5. Ein Niederhalter-Kraftsensor ist mit Bezugszeichen 13 angezeigt. Diese Presse kann zum Ziehen unregelmäßiger Blechformteile gleichermaßen verwendet werden. Fig. 1b shows the basic structure of a known single-acting Press device 9 as a single-acting press hydraulic pulling device 10 with hydraulic cylinders 11 and the pull ring 3 described for FIG. 1a, the Hold-down device 4 and the punch 5. A hold-down force sensor is indicated with reference number 13. This press can be used to pull irregular sheet metal parts equally be used.
Stand der Technik sind demzufolge Pressen- und Werkzeugsysteme, die die Niederhalterkraft während des Ziehprozesses verändern können. Hierbei können die hydraulische Zieheinrichtungen 10, bestehend aus einzeln über nicht näher dargestellte Servoventile ansteuerbaren Hydraulikzylindern 11, die Niederhalterkräfte FN direkt über die Kolbenstangen 12 (vgl. Bild 1b) oder indirekt über nicht dargestellte Pinolen in den Niederhalter 4 einleiten (siehe z.B. DE 41 12 656 A1). The state of the art are therefore press and tool systems that can change the hold-down force during the drawing process. In this case, the hydraulic pulling devices 10, consisting of hydraulic cylinders 11 that can be individually controlled via servo valves, not shown, can introduce the hold-down forces F N directly into the hold-down device 4 via the piston rods 12 (see FIG. 1b) or indirectly via sleeves (not shown, for example, DE 41 12 656 A1).
Bei diesen Systemen sind verschiedene Möglichkeiten zur Steuerung des Materialflusses bekannt. There are various options for these systems Control of material flow known.
Oftmals werden vor dem Ziehprozeß festgelegte Niederhalterdruckprofile über dem Ziehweg in einem Regelkreis vorgegeben, der die gewünschte Niederhalterkraft während des Ziehprozesses realisiert. Nachteil dieser Systeme ist, daß die vordefinierten Niederhalter-Druckprofile zur Steuerung des Materialflusses von gleichbleibenden Reibungsverhältnissen zwischen Niederhalter 4 und Blech 2 bzw. zwischen Ziehring und Blech ausgehen. Often times are set before the drawing process Hold down pressure profiles over the drawing path in a control loop given the desired hold-down force during the Drawing process realized. The disadvantage of these systems is that the predefined hold-down pressure profiles for control the material flow from constant Friction between hold-down device 4 and plate 2 or go out between drawing ring and sheet metal.
Eine wesentliche Verbesserung stellen Regelkreise dar, die Umformparameter wie den Flanschkanteneinlauf, die Stempelkraft oder die Faltenhöhe des aktuell ablaufenden Ziehprozesses als Regelgröße verwenden. Control loops represent a significant improvement Forming parameters such as the flange edge inlet Stamp force or the fold height of the currently running Use the drawing process as a control variable.
Diese Größen sind unter anderem direkt abhängig von den Reibungsverhältnissen zwischen Werkstück, Niederhalter, Ziehstempel und Ziehring usw. Kommt es zu einer Veränderung der Reibungsverhältnisse, z. B. durch Veränderung der Blechoberfläche, des Schmiermittels oder der Schmiermittelmenge usw., so kann durch ein automatisches Reagieren des Systems die Niederhalterkraft so angepaßt werden, daß der angestrebte Verlauf der Führungsgröße, die den optimalen Materialfluß und damit den gewünschten Umformprozeß charakterisiert, wieder erreicht wird. Von Nachteil ist bei dieser Vorgehensweise, daß der Flanschkanteneinlauf sensorisch aufwendig zu messen ist und die Meßsignale bei geringem Einzug ein nicht hinreichendes Signal als Führungsgröße liefern. Der Faltenhöhensensor ist aus der Literatur bekannt und scheint als Führungsgröße für den Aufbau von Regelkreisen zur Unterdrückung von Falten 1. Art, also Falten im Flansch des Ziehteils, gut geeignet zu sein. Among other things, these sizes are directly dependent on the Friction between workpiece, hold-down, Drawing stamp and drawing ring etc. If there is a change the friction, e.g. B. by changing the Sheet metal surface, lubricant or Amount of lubricant, etc., can by an automatic Reaction of the system adjusted the hold-down force be that the desired course of the benchmark, the the optimal material flow and thus the desired one Forming process characterized, is achieved again. From The disadvantage of this approach is that the Flange edge inlet is difficult to measure by sensors and the measurement signals are insufficient when the feed is small Deliver signal as a command variable. The pleat height sensor is known from the literature and seems to be a leader for the construction of control loops to suppress wrinkles 1. Kind, i.e. folds in the flange of the drawn part, well suited to be.
Die Stempelkraft FS beinhaltet zwar die Kräfte der Reibung zwischen Blech 2 und Niederhalter 4 und der Reibung zwischen Ziehring 3 und Niederhalter 4. Sie beinhaltet jedoch auch alle anderen Reibungskräfte sowie die Umformkräfte, so daß sie als Führungsgröße für die Steuerung des Materialflusses nur bedingt geeignet ist. Die hiermit erreichten Erfahrungen bestätigen die Kritik an der Verwendung dieser Größen als Führungsgrößen zur Materialflußsteuerung. The punch force F S contains the forces of friction between sheet metal 2 and hold-down device 4 and the friction between drawing ring 3 and hold-down device 4. However, it also includes all other frictional forces and the forming forces, so that they are only of limited use as a control variable for controlling the material flow is. The experience gained with this confirms the criticism of the use of these variables as reference variables for material flow control.
In den letzten Jahren wurden demzufolge verschiedene Systeme mit Regelungen der Stempelkraft, der Faltenhöhe und des Flanschkanteneinlaufs der Platine in verschiedenen Patenten und Veröffentlichungen erwähnt. So wird beispielsweise im Patent DE 43 38 828 C2 (nächstliegender Stand der Technik) der Mercedes-Benz AG ein System zur Regelung des Kanteneinlaufs vorgestellt, das auch eine Erweiterung auf eine Stempelkraftregelung vorsieht. Eine ähnliche Anordnung ist in der DE 42 42 442 A1 der gleichen Anmelderin gezeigt. As a result, various systems have been used in recent years with regulations of the stamp force, the fold height and the Flange edge inlet of the board in various patents and publications mentioned. For example, in Patent DE 43 38 828 C2 (closest prior art) Mercedes-Benz AG a system for Regulation of the edge infeed presented, which is also a Extension to a stamp force regulation. A Similar arrangement is the same in DE 42 42 442 A1 Shown to the applicant.
Der Erfindung liegt die Aufgabe zugrunde, die bekannten Ziehverfahren und Ziehvorrichtungen zu verbessern und insbesondere ein genaueres Erfassen der Ziehparameter und der zugehörigen Prozeßabläufe zu ermöglichen. Dabei soll insbesondere die Reibungskraft zwischen Blech und Niederhalter bzw. Blech und Ziehring als Regelgröße berücksichtigt werden. The invention has for its object the known To improve drawing methods and drawing devices and in particular a more precise recording of the drawing parameters and the associated To enable process flows. In particular, the Frictional force between sheet and hold-down or sheet and Drawing ring can be considered as a control variable.
Diese Aufgabe ist durch die Merkmale des Anspruchs 1 hinsichtlich des Verfahrens und durch die Merkmale des Anspruchs 10 hinsichtlich der Vorrichtung gelöst. Weitere Ausgestaltungen der Erfindung können den Unteransprüchen entnommen werden. This object is due to the features of claim 1 of the method and by the features of claim 10 solved with regard to the device. Other configurations the invention can be found in the subclaims.
Die Erfindung wird im nachfolgenden Ausführungsbeispiel anhand der Figurendarstellung näher erläutert: The invention is illustrated in the following embodiment explained in more detail using the figure:
Die Figuren 1a, 1b zeigen den bekannten Stand der Technik; Figures 1a, 1b show the known prior art;
Die Fig. 2 zeigt eine schematische Darstellung einer Zieheinrichtung mit Regelungseinrichtung, wobei - soweit möglich - gleiche Teile mit gleichen Bezugszeichen wie zu Fig. 1a, 1b bezeichnet sind. Fig. 2 shows a schematic representation of a Pulling device with control device, where - as far as possible - the same parts with the same Reference numerals as to Fig. 1a, 1b are designated.
Bei dem Verfahren sowie der zugehörigen Einrichtung 20 werden zur Materialflußsteuerung ein Regelkreis 21 verwendet, der es unter Verwendung der Niederhalterkraft FN als Stellgröße 22 der Niederhalterkraft FN erlaubt, die an der Oberfläche 23 des Niederhalters und/oder des Ziehrings 3 wirkende Reibung nach einer vorgegebenen Führungsgröße 24 (Reibungskraft FR über dem Ziehweg s) zu regeln (Fig. 2). Daher erfolgt die Messung der Reibungskraft FR über einen Reibungskraftsensor 25, 25', 25'', der vorzugsweise als Drei-Komponenten-Piezokraftmeßelement 26 ausgebildet ist, d.h. auf einem piezoelektrischen Effekt basiert. Derartige Sensoren 25', 25'' können insbesondere auch an vorgegebenen Stellen des Niederhalters 4 und/oder auch des Ziehrings 3 eingebaut werden (siehe gestrichelt eingezeichnet in Fig. 2). In the method and the associated device 20, a control circuit 21 is used for material flow control, which, using the hold-down force F N as a manipulated variable 22 of the hold-down force F N, allows the friction acting on the surface 23 of the hold-down device and / or the drawing ring 3 after a friction predetermined command variable 24 (friction force F R over the pull path s) to regulate (Fig. 2). The friction force F R is therefore measured via a friction force sensor 25, 25 ′, 25 ″, which is preferably designed as a three-component piezo force measuring element 26, ie based on a piezoelectric effect. Such sensors 25 ', 25''can in particular also be installed at predetermined positions on the hold-down device 4 and / or also on the drawing ring 3 (see the broken line in FIG. 2).
Der in Fig. 2 gezeigte Regelkreis reagiert automatisch auf die Veränderungen im tribologischen System 40, d.h. er regelt automatisch die Veränderungen der mit dem Reibkraftsensor 25 gemessenen Reibkraft, die beispielsweise durch Änderungen der Schmiermittelmenge und Schmierstoffart, der Blechoberfläche usw. verursacht werden. Zum Aufbau des Systems wird eine Pressen- oder Werkzeugeinrichtung 20 benötigt, die eine Veränderung der Niederhalterkraft 30 während des Ziehvorgangs erlaubt. Dieses ist bei Einsatz hydraulischer Ziehkissen im Tisch einfachwirkender Pressen, wie sie prinzipiell auch Fig. 1b zeigt, möglich. Hierfür werden bestimmte Bereiche eines vorzugsweise segmentierten Niederhalters 4 mit oberen Segment 27 und unterem Segment 28 über jeweils einen eigenen, in der Presse 20 oder auch ggf. im Werkzeug angeordneten Hydraulikzylinder 11 beaufschlagt, wobei jeder Zylinder 11 über ein eigenes Servoventil 29 angesteuert werden kann. Das Servoventil 29 regelt dabei den Ölfluß und bestimmt somit den im Zylinder 11 wirkenden Druck und damit die am Segment 27 herrschende Niederhalterkraft 30. Diese kann sowohl über eine Druckmessung im Zylinder 11 oder über einen im Kraftfluß angeordneten Niederhalterkraftsensor 25, 26 ermittelt werden. The control loop shown in FIG. 2 reacts automatically the changes in the tribological system 40, i.e. he regulates automatically the changes with the friction force sensor 25 measured friction force, for example, by changes in the Lubricant quantity and type of lubricant, the sheet surface etc. are caused. To build the system, a Press or tool device 20 required, the one Change of hold-down force 30 during the drawing process allowed. This is when using hydraulic die cushions in the Table of single-acting presses, as also shown in Fig. 1b shows possible. For this, certain areas are one preferably segmented hold-down 4 with upper segment 27 and lower segment 28 each have their own, in the Press 20 or possibly arranged in the tool Hydraulic cylinder 11 acts, each cylinder 11th can be controlled via its own servo valve 29. The Servo valve 29 controls the oil flow and thus determines the pressure acting in the cylinder 11 and thus the pressure on the segment 27 prevailing hold-down force 30 Pressure measurement in the cylinder 11 or via one in the power flow arranged hold-down force sensor 25, 26 can be determined.
Das Segment stützt sich demzufolge über Drei-KomponentenPiezokraftmeßelemente 26 ab. Diese erlauben die Messung einer Reibungskraft 25' und der auf das Segment 27 wirkenden Niederhalterkraft 30. Gegebenenfalls ist auch lediglich ein Reibungskraftsensor in den Niederhalter des Ziehwerkzeuges einbringbar. Eine Segmentierung des Niederhalters kann ggf. bei entsprechend "weicher" elastischer Ausführung entfallen. The segment is therefore based on three-component piezo force measuring elements 26 from. These allow the measurement of one Frictional force 25 'and that acting on the segment 27 Hold-down force 30 Frictional force sensor in the holding-down device of the drawing tool applicable. A segmentation of the hold-down device can with a correspondingly "soft" elastic design.
Kennt man aus einer experimentellen oder theoretischen Analyse den Verlauf der Reibungskraft FR über dem Stößelweg s für den gewünschten optimalen Materialfluß, so ist es mit Hilfe der Regelungstechnik und der Verwendung der Niederhalterkraft als Stellgröße möglich, auch bei einer Veränderung der Eingangsbedingungen stets den gleichen optimalen Reibungskraftverlauf zu erreichen. If you know from an experimental or theoretical analysis the course of the frictional force F R over the ram path s for the desired optimal material flow, it is possible with the help of control technology and the use of the hold-down force as a manipulated variable, even if the input conditions change, always the same optimal Achieve frictional force curve.
Gegebenenfalls kann der Reibungskraftsensor in Eckenbereichen, in denen Falten zu unterdrücken sind, mit einem aus der Literatur bekannten Faltenhöhensensor gekoppelt werden, so daß stets gewährleistet ist, daß die Niederhalterkraft mindestens so groß ist, daß Falten im Flansch mit Sicherheit vermieden werden. If necessary, the friction force sensor in Corner areas where wrinkles are to be suppressed with coupled to a pleat height sensor known from the literature are, so that it is always guaranteed that the Hold-down force is at least so great that folds in the Flange can be avoided with certainty.
Innerhalb des Regelkreises wird als Steuerungseinheit ein Rechner 31 mit Analog/Digital-Schnittstelle verwendet. In diesem Rechner kann der gewünschte Kurvenverlauf 32 der Reibungskraft über dem Stößelweg als Führungsgröße 24 abgelegt werden. Zu jeder Position des Stößels 33, die von einem Wegmeßelement 34 gemessen wird, kann aus dieser Steuereinheit 31 der zugeordnete Wert der Reibungskraft ausgelesen werden. Dieser wird dem Regler 35 als Sollwert 36 vorgegeben. Mit Hilfe des Reibkraftsensors 25 und des nachgeschalteten Verstärkers 37 kann der zugehörige Istwert der Reibungskraft an den zweiten Eingang des Reglers 35 gegeben werden. Stellt der Regler eine Differenz zwischen Sollwert 36 und Istwert 38 fest, generiert er ein Stellsignal 39, das einem Stellglied (Servoventil 29) des Hydraulikkreislaufes des Segmentes zugeführt wird. Das Signal beeinflußt das Stellelement derart, daß sich der Istwert der Reibungskraft so ändert, daß die Differenz zwischen Istwert 38 und Sollwert 36 minimiert wird. Within the control loop is a control unit Computer 31 with analog / digital interface used. In the desired curve shape 32 of the Frictional force over the tappet travel as reference variable 24 be filed. For each position of the plunger 33, the a displacement measuring element 34 is measured, from this Control unit 31 the assigned value of the friction force be read out. This is the controller 35 as setpoint 36th given. With the help of the friction force sensor 25 and downstream amplifier 37 can the associated actual value the frictional force at the second input of the controller 35 are given. The controller places a difference between Setpoint 36 and actual value 38 fixed, it generates an actuating signal 39, which is an actuator (servo valve 29) of Hydraulic circuit of the segment is supplied. The signal influences the control element in such a way that the actual value of the Frictional force changes so that the difference between the actual value 38 and setpoint 36 is minimized.
Dadurch ist es möglich, Reibungskraftverläufe 32, die den gewünschten Umformprozeß unabhängig von den momentanen Reibungsverhältnissen charakterisieren, als Führungsgröße vorzugeben. This makes it possible to determine the friction force curves 32 that the desired forming process regardless of the current one Characterize frictional relationships as a benchmark to specify.
Der Regelkreis reagiert demzufolge selbständig auf Veränderungen der Reibung zwischen Niederhalter und Blech sowie zwischen Ziehring und Blech, hervorgerufen durch Veränderungen der Schmierstoffart oder -menge auf dem Blech, Veränderungen der Blechoberfläche und durch Werkzeugverschluß oder dergleichen (tribologische Eigenschaften). The control loop reacts accordingly independently on changes in the friction between Hold-down device and sheet metal and between drawing ring and sheet metal, caused by changes in the type or quantity of lubricant on the sheet, changes in the sheet surface and by tool lock or the like (tribological Characteristics).
- 11
- Presseneinrichtung Press device
- 22nd
- Werkstück workpiece
- 33rd
- Ziehring Drawing ring
- 44th
- Niederhalter Hold-down
- 55
- Ziehstempel Drawing stamp
- 66
- Ziehteilflansch Drawn flange
- 77
- Ziehkante Pull edge
- 88th
- Ziehteilwandung (Zarge) Drawn part wall (frame)
- 99
- Presseneinrichtung Press device
- 1010th
- hydraulische Zieheinrichtung hydraulic pulling device
- 1111
- Hydraulikzylinder Hydraulic cylinder
- 1212th
- Kolbenstange Piston rod
- 1313
- Niederhalter-Kraftsensor Hold-down force sensor
- 2020th
- erfindungsgemäße Einrichtung device according to the invention
- 2121
- Regelkreis Control loop
- 2222
- Stellgröße/Niederhalterkraft Manipulated variable / hold-down force
- 2323
- Oberfläche surface
- 2424th
- Führungsgroße Leadership
- 2525th
- Reibungskraftsensor Friction force sensor
- 2626
- Piezokraftmeßelement Piezo force measuring element
- 2727
- oberes Segment upper segment
- 2828
- unteres Segment lower segment
- 2929
- Servoventil Servo valve
- 3030th
- Niederhalterkraft Hold-down force
- 3131
- Rechner computer
- 3232
- gewünschter Kurvenverlauf desired curve shape
- 3333
- Stößel Pestle
- 3434
- Wegmeßelement Position measuring element
- 3535
- Regler Regulator
- 3636
- Sollwert Setpoint
- 3737
- Verstärker amplifier
- 3838
- Istwert actual value
- 3939
- Stellsignal Control signal
- 4040
-
tribologisches System
Stempelkraft FS
Niederhalterkraft FN tribological system
Stamp force F S
Hold-down force F N
Claims (13)
- Method of controlling the flow of material during the drawing of work pieces (2) such as sheet metal mouldings, wherein a control loop (21), including a preferably hydraulic drawing means, regulates a holding-down force (F) as a control variable, characterized in that via a friction force sensor (25) arranged in a holding-down means (4) and/or in a drawing ring (3) of the tool, the friction force between the work piece (2) and the holding-down means (4) and/or the friction force between the drawing die (3) and the work piece (2) is measured, and said friction force follows a given, experimentally or theoretically determined friction force-drawing punch path curve (32) in the control loop (21) as a regulating variable.
- Method according to Claim 1, characterized in that the holding-down force (FN) is applied by hydraulic cylinders (11), preferably controlled by servo valve, or indirectly by mechanical means such as centre sleeves or vertically adjustable bolts.
- Method according to Claim 1 or 2, characterized in that the control loop (13) reacts independently to changes in friction between the holding-down means (4) and the metal sheet (2) and/or between the drawing die (3) and the metal sheet (2) in the sense of a process optimisation.
- Method according to one of the preceding claims, characterized in that hydraulic and/or pneumatic cylinders or actuators controlled in the drawing tool are provided, whereby in particular the functions of the drawing means are integrated into the tool, and whereby the control loop (13) serves to regulate the holding-down force (FN) using the friction force as a regulating variable.
- Method according to one of the preceding claims, characterized in that a fold height sensor arranged in the drawing tool is incorporated into the control loop (13) in such a manner as to constantly ensure that folds in the flange of the drawing part do not exceed a given maximum fold height.
- Method according to one of the preceding claims, characterized in that a control loop (13) for a drawing means is configured such that by means of a measuring element, in particular a friction force sensor (25), and by predetermination of an optimum control curve, in particular a friction force curve (32) over the drawing path, a control loop (13) is configured which uses the measured signal and in particular the friction force as regulating variable and the holding-down force (FN) as a control variable in such a manner that the control loop (13) independently reacts to changes in tribological conditions.
- Method according to one of the preceding claims, characterized in that a segmented holding-down means (4) is used in such a way that each segment of the holding-down means may be regulated with respect to friction force by an associated control loop which uses the holding-down force (FN) of the segment as a control variable.
- Method according to one of Claims 1-6, characterized in that a single-part holding-down means (4) is used, which is so elastic that it may virtually be regulated segment by segment with respect to regulation of the friction force according to a given friction force curve.
- Method according to one of the preceding claims, characterized in that friction force sensors (25) are provided in the holding-down means (4) or drawing die (3) and by means of these regulation of the friction force of a specific region is conducted according to a given curve course of the friction force over the drawing path with the holding-down force (FN) as a control variable.
- Device (20) for performing the method according to one or more of the preceding claims for controlling the flow of material during the drawing of sheet metal parts (2) with a control loop (13) for a drawing means having a holding-down means (4) and a drawing die (3), characterized in that the control loop (13) comprises a friction force sensor (25) as well as a given optimum friction force curve (32) over the drawing path, wherein the friction force may be used as regulating variable and the holding-down pressure force as control variable such that the control loop (13) independently reacts to changes in the tribological conditions by changing the holding-down force (FN).
- Device according to Claim 10, characterized in that the holding-down means (4) is of segmented configuration such that each segment may be regulated with respect to the friction force by its own associated control loop, which uses the holding-down force (FN) of the segment as a control variable.
- Device according to Claim 10, characterized in that the holding-down means (4) is configured in a single piece and is so elastic that it may virtually be regulated segment by segment with respect to regulation of the friction force according to a given friction force curve.
- Device according to one of Claims 10 to 12, characterized in that friction force sensors (25) are provided in the holding-down means (4) or drawing die (3) and by means of these regulation of the friction force of a specific region is conducted according to a given curve course of the friction force over the drawing path with the holding-down force (FN) as a control variable.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19617965 | 1996-05-06 | ||
| DE19617965 | 1996-05-06 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0806256A2 EP0806256A2 (en) | 1997-11-12 |
| EP0806256A3 EP0806256A3 (en) | 1998-01-21 |
| EP0806256B1 true EP0806256B1 (en) | 1999-11-10 |
Family
ID=7793355
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP97107440A Expired - Lifetime EP0806256B1 (en) | 1996-05-06 | 1997-05-06 | Method for controlling the material flow during the drawing of sheet metal parts and device for carrying out the method |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0806256B1 (en) |
| DE (2) | DE19718841A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE518856C2 (en) * | 1998-07-17 | 2002-11-26 | Ep Technology Ab | Tool with hydraulically controlled counterbar |
| DE10210573A1 (en) * | 2002-03-11 | 2003-10-02 | Dieffenbacher Gmbh Maschf | Hydroelastic deep-drawing device |
| DE10233008A1 (en) | 2002-07-20 | 2004-02-12 | Nothelfer Gmbh | Process for material flow control when deep-drawing sheet metal and deep-drawing tool |
| NL1021738C2 (en) * | 2002-10-24 | 2004-04-27 | Tno | Method and device for reducing crease formation during deep drawing. |
| DE10329898B4 (en) * | 2003-07-03 | 2006-09-28 | Thyssenkrupp Steel Ag | Method and apparatus for forming sheet metal blanks |
| DE10331939B4 (en) * | 2003-07-15 | 2014-09-18 | Bayerische Motoren Werke Aktiengesellschaft | sheet-metal forming |
| DE102004059141A1 (en) * | 2004-12-08 | 2006-06-14 | Wieber, Christian, Dipl.-Ing.(FH), Batu Caves | Hydraulic press for deforming sheet metal comprises working cylinders integrated into a press frame disposed on a relatively short lift, interlocking locking elements for transferring closing forces to a tappet and a driving unit |
| US10786842B2 (en) | 2018-09-12 | 2020-09-29 | Fca Us Llc | Draw-in control for sheet drawing |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4338828C2 (en) * | 1993-11-13 | 1996-01-25 | Daimler Benz Ag | Process for operating drawing presses and drawing press suitable therefor |
-
1997
- 1997-05-06 EP EP97107440A patent/EP0806256B1/en not_active Expired - Lifetime
- 1997-05-06 DE DE19718841A patent/DE19718841A1/en not_active Withdrawn
- 1997-05-06 DE DE59700677T patent/DE59700677D1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE59700677D1 (en) | 1999-12-16 |
| EP0806256A2 (en) | 1997-11-12 |
| EP0806256A3 (en) | 1998-01-21 |
| DE19718841A1 (en) | 1997-11-13 |
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