EP0713735A1 - Length compensation means in a clamping device between the upper and lower tool of a press - Google Patents

Length compensation means in a clamping device between the upper and lower tool of a press Download PDF

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Publication number
EP0713735A1
EP0713735A1 EP95117213A EP95117213A EP0713735A1 EP 0713735 A1 EP0713735 A1 EP 0713735A1 EP 95117213 A EP95117213 A EP 95117213A EP 95117213 A EP95117213 A EP 95117213A EP 0713735 A1 EP0713735 A1 EP 0713735A1
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EP
European Patent Office
Prior art keywords
pressure
short
stroke
compensation
cylinder
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EP95117213A
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German (de)
French (fr)
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EP0713735B1 (en
Inventor
Wieland Dr. Petter
Gregor Geist
Andreas Schlag
Markus Dr. Müller
Wolf-Eckehart Gödel
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Umformtechnik Erfurt GmbH
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Umformtechnik Erfurt GmbH
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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
    • B21D24/10—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 length compensation device in a clamping device between the upper and lower tool of a press to achieve the sheet metal holding force, wherein the clamping device can be formed either by a die cushion or by a sheet metal holder.
  • a hydraulic cushion assembly for a press which is intended to apply a cushion force that is uniform for a workpiece across all pressure bolts.
  • a plurality of short-stroke cylinders that are fluidly connected to one another and whose short-stroke pistons are operatively connected to the pressure bolts are arranged on a pressure-pin plate that can be moved by the die cushion.
  • the short-stroke cylinders are connected to a hydraulic supply device to supply them with pressure medium.
  • the hydraulic supply device contains elements for changing an initial pressure in the short-stroke cylinders. This change in pressure takes place before the start of the pressing operation.
  • the problem of the invention is to provide a compensation device which ensures with simple technical means that all pressure pins transmit the same force, the force effect of the short-stroke cylinders among one another is almost excluded before the full force connection between the functional elements is achieved and the contact pattern of all pressure pins achieved in this way is reproducible is.
  • the prerequisite for this is that all pressure bolts experience the same compression under load. This in turn makes it a condition that geometric deviations of the functional elements lying in the power flow are compensated for.
  • the mechanically limited space in the compensation cylinder can advantageously be changed as a function of the number of pressure bolts used per tool and the sum of the geometric deviation of the functional elements located in the power flow.
  • Another advantage of the solution lies in the fact that although all of the pressure pin points of the pressure pin plate can be occupied by short-stroke cylinders, expediently, only the pressure-pin points necessary according to an empirical determination are occupied by short-stroke cylinders within the framework of the standardized grid. While the number and position of the pressure bolts for each tool are adjusted manually in the known form when the tool is changed, the short-stroke cylinders which are not necessary but are present on the pressure bolt plate can be depressurized and thus switched off communicating system can be disconnected.
  • the pressure pin points required for the specific tool can be occupied with pressure pins and the short-stroke pistons of the pressure pin points that are not required can still be operated "blindly".
  • all existing short-stroke cylinders can be operated and only the pressure pin points required for the specific tool can be assigned pressure bolts.
  • the equipment can also be designed so that the individual short-stroke cylinders can be shifted in their assignment to the pressure bolts or removed and retrofitted when the tool is changed. If the number of pressure bolts and / or geometric deviations of the functional elements changes, a volume change in the compensation space in the compensation cylinder is expedient.
  • the short-stroke cylinders can also be designed with different active surfaces.
  • the compensation piston 11 is in its mechanical, lower end position. With the first contact between the driving system of press ram 1 with the upper tool and the stationary drawing cushion with the pressure pin plate 3, the drawing cushion piston 18, the short-stroke cylinders 5 and the pressure pin 7, the relevant short-stroke piston 6 is displaced by the displacement stroke 9.
  • This displacement stroke 9 is in each case Short stroke cylinder 5 different and designated x1 to x n .
  • all pressure bolts 7 follow until the start of drawing and displace pressure medium via the connecting lines 20 and 14 into the compensation chamber 22 of the compensation cylinder 10.
  • the pressure piston is displaced from the short-stroke cylinders 5 and the compensation piston 11 is displaced by the compensation stroke 12
  • This compensation stroke 12 and thus the sum of the pressure medium displaced from the short stroke cylinders 5 is determined by the adjustable stroke limiter 13.
  • Due to the mechanically limited volume absorption in the compensation cylinder 10, the displacement stroke 9 of the short-stroke piston 6 is interrupted in the drawing direction.
  • the pressure bolts are thus driven further against the acting die cushion force 23, which is supported on the press table 4 via the crossmember 19.
  • the qualitative position of the functional elements at the start of drawing is shown in FIG. 2.
  • the directional control valve 17 is located in the blocking position from the connecting line 14 in the direction of the pressure medium container 16.
  • the pressure relief valve 24 is arranged parallel to the directional control valve 17 to protect the hydraulic system against overload.
  • the directional control valve 17 can also be designed as a continuous valve.
  • the pressure medium is returned from the compensation chamber 22 into the short-stroke cylinders 5, as a result of which the short-stroke pistons 6 reach their starting position.
  • the pressure medium is acted upon by pneumatic pressure via the pressure control device 15 and the directional control valve 21.
  • the pressure in the pressure medium container 16 causes a corresponding force through the differential area, which causes the pressure medium to flow back from the compensation chamber 22 guaranteed.
  • the pressure pin plate 3 has a standardized number of pressure pin points 25. As is known, the need for these individual pressure pin points 25 per tool is very different. In addition to the possibility of equipping all or the pressure pin points 25 required only for one tool with short-stroke cylinders 5, it is proposed to operate short-stroke cylinders 5 in a certain period of time after an empirically determined necessary pressure pin point assignment for tools and only the pressure pin points 25 required for the respective tool with pressure bolts 7 to equip or to deactivate the pressure pin points 25 that are not required by "depressurizing" the short-stroke cylinders 5 that are not required. The removal of the pressure bolts from the platen, not shown, is not a condition.
  • each short-stroke cylinder 5 is assigned a directional valve 26 and, in addition, all short-stroke cylinders 5 are jointly assigned the directional valve 27.
  • the directional control valves 26 and 27 are arranged between the short-stroke cylinders 5 and the pressure medium container 16 and connected in series. They enable the short-stroke cylinders 5 which are not required for a tool to be relieved of pressure and thus to be put out of operation. If necessary, the Number of short stroke cylinders 5 can be adjusted for each tool.
  • the short-stroke cylinders 5 can be changed in their spatial arrangement or can be retrofitted and retrofitted.
  • a volume change of the compensation space 22 by means of the stroke limiter 13 is expedient.

Abstract

Length compensating arrangement for a hold-down between the top and the bottom tool of a press, in which a number of interconnected short-stroke cylinders (5) with pressure pins (7) connected to their piston rods (6) are mounted on a pressure pin plate (3) to clamp the sheet blank between the top and bottom tool. The short-stroke cylinders (5) are pressure connected to a compensating cylinder (10), so that prior to the start of drawing the fluid volume displaced in the short-stroke cylinders (5) by forces acting on the pressure pins (7) is stored in the compensating chamber (22) of the compensating cylinder (10).

Description

Die Erfindung betrifft eine Längenkompensationseinrichtung in einer Klemmeinrichtung zwischen Ober- und Unterwerkzeug einer Presse zum Erreichen der Blechhaltekraft, wobei die Klemmeinrichtung entweder durch ein Ziehkissen oder durch einen Blechhalter gebildet werden kann.The invention relates to a length compensation device in a clamping device between the upper and lower tool of a press to achieve the sheet metal holding force, wherein the clamping device can be formed either by a die cushion or by a sheet metal holder.

Nach der EP 0 531 140 A1 ist ein hydraulisches Kissenaggregat für eine Presse bekannt, das eine für ein Werkstück einheitliche Kissenkraft über alle Druckbolzen aufbringen soll. Dazu sind auf einer vom Ziehkissen bewegbaren Druckbolzenplatte eine Mehrzahl von untereinander fließverbundenen Kurzhubzylindern angeordnet, deren Kurzhubkolben mit den Druckbolzen wirkverbunden sind. Die Kurzhubzylinder sind zu ihrer Versorgung mit Druckmittel mit einer Hydraulikversorgungseinrichtung verbunden. Die Hydraulikversorgungseinrichtung enthält Elemente, um einen Anfangsdruck in den Kurzhubzylindern zu ändern. Diese Druckänderung erfolgt vor Beginn der Preßoperation.
Bei dieser mit hohem technischen Aufwand betriebenen Lösung kommen die im Kraftfluß liegenden Funktionselemente durch im praktischen Pressenbetrieb gegebene verschleiß- und/oder fertigungsbedingte geometrische Abweichungen zu unterschiedlichen Zeitpunkten zur Wirkung. Durch die Federwirkung des Druckmittels entstehen nach dem Kontakt des ersten Druckbolzens bis zur Erreichung gleicher Druckbolzenkräfte Kippkräfte auf das gesamte System Stößel - Werkzeug - Druckbolzenplatte.According to EP 0 531 140 A1, a hydraulic cushion assembly for a press is known which is intended to apply a cushion force that is uniform for a workpiece across all pressure bolts. For this purpose, a plurality of short-stroke cylinders that are fluidly connected to one another and whose short-stroke pistons are operatively connected to the pressure bolts are arranged on a pressure-pin plate that can be moved by the die cushion. The short-stroke cylinders are connected to a hydraulic supply device to supply them with pressure medium. The hydraulic supply device contains elements for changing an initial pressure in the short-stroke cylinders. This change in pressure takes place before the start of the pressing operation.
In this solution, which is operated with a high level of technical complexity, the functional elements located in the power flow come into effect at different times as a result of wear and / or production-related geometric deviations given in practical press operation. The spring action of the pressure medium creates tipping forces on the entire plunger - tool - pressure pin plate system after the first pressure pin comes into contact until the same pressure pin forces are reached.

Das Problem der Erfindung ist, eine Kompensationseinrichtung zu schaffen, die mit einfachen technischen Mitteln sichert, daß alle Druckbolzen die gleiche Kraft übertragen, die Kraftwirkung der Kurzhubzylinder untereinander vor Erreichen des vollen Kraftschlusses zwischen den Funktionselementen nahezu ausgeschlossen und das so erreichte Tragbild aller Druckbolzen reproduzierbar ist. Voraussetzung hierfür ist, daß alle Druckbolzen unter Last die gleiche Stauchung erfahren. Dies wiederum macht zur Bedingung, daß geometrische Abweichungen der im Kraftfluß liegenden Funktionselemente kompensiert werden.The problem of the invention is to provide a compensation device which ensures with simple technical means that all pressure pins transmit the same force, the force effect of the short-stroke cylinders among one another is almost excluded before the full force connection between the functional elements is achieved and the contact pattern of all pressure pins achieved in this way is reproducible is. The prerequisite for this is that all pressure bolts experience the same compression under load. This in turn makes it a condition that geometric deviations of the functional elements lying in the power flow are compensated for.

Erfindungsgemäß wird das durch die in den kennzeichnenden Teilen des Patentanspruches 1 beschriebenen Merkmale erreicht. Weitere Ausgestaltungen der Erfindung sind in den Ansprüchen 2 bis 7 beschrieben.According to the invention this is achieved by the features described in the characterizing parts of patent claim 1. Further refinements of the invention are described in claims 2 to 7.

Der Vorteil dieser Lösung besteht darin, daß von Kontaktbis Ziehbeginn alle Geometrieabweichungen der während des Ziehprozesses im Kraftfluß liegenden Funktionselemente kompensiert werden durch nahezu druckloses Verdrängen von Druckmittel aus den zu einem kommunizierenden System zusammengeschlossenen Kurzhubzylindern in den mechanisch begrenzen Raum eines Kompensationszylinders. Dabei werden Kraftwirkungen der Kurzhubzylinder untereinander bis zum Erreichen des vollen Kraftschlusses zwischen Stößel und Ziehkissen oder Blechhalter weitgehend ausgeschlossen. Mit Ziehbeginn sichert das kommunizierende hydraulische System gleichen Druck in allen Kurzhubzylindern und damit die beabsichtigte gleiche Kraft aller Druckbolzen. In Abhängigkeit von der Anzahl der je Werkzeug im Einsatz befindlichen Druckbolzen und von der Summe der geometrischen Abweichung der im Kraftfluß liegenden Funktionselemente ist der mechanisch begrenzte Raum im Kompensationszylinder vorteilhafterweise veränderbar. Ein weiterer Vorteil der Lösung liegt darin, daß zwar alle Druckbolzenpunkte der Druckbolzenplatte mit Kurzhubzylindern belegt sein können, jedoch zweckmäßigerweise nur die nach einer empirischen Ermittlung notwendigen Druckbolzenpunkte im Rahmen des genormten Rasters mit Kurzhubzylindern belegt werden. Während die Anpassung der Anzahl und Lage der Druckbolzen für jedes Werkzeug manuell in der bekannten Form bei Werkzeugwechsel erfolgt, können die nicht notwendigen aber auf der Druckbolzenplatte vorhandenen Kurzhubzylinder drucklos geschaltet und so vom kommunizierenden System abgekoppelt werden. Ebenfalls können die werkzeugspezifisch notwendigen Druckbolzenpunkte mit Druckbolzen belegt werden und die weiterhin vorhandenen Kurzhubkolben der nicht notwendigen Druckbolzenpunkte "blind" weiter betrieben werden. Alternativ können auch alle vorhandenen Kurzhubzylinder betrieben werden und nur die werkzeugspezifisch notwendigen Druckbolzenpunkte mit Druckbolzen belegt werden. Die Ausrüstung kann auch so gestaltet werden, daß beim Werkzeugwechsel die einzelnen Kurzhubzylinder in ihrer Zuordnung zu den Druckbolzen verschiebbar bzw. ab- und nachrüstbar sind. Bei Veränderung der Anzahl der Druckbolzen und/oder Geometrieabweichungen der Funktionselemente ist eine Volumenänderung des Kompensationsraumes im Kompensationszylinder zweckmäßig. Die Kurzhubzylinder können auch mit unterschiedlichen Wirkflächen ausgebildet werden.The advantage of this solution is that from the start of contact to the start of drawing, all geometrical deviations of the functional elements which are in the power flow during the drawing process are compensated for by the almost pressure-free displacement of pressure medium from the short-stroke cylinders which are connected to form a communicating system into the mechanically limited space of a compensation cylinder. Force effects of the short-stroke cylinders with each other are largely excluded until the full force connection between the ram and die cushion or sheet metal holder is achieved. When the drawing begins, the communicating hydraulic system ensures the same pressure in all short-stroke cylinders and thus the intended same force of all pressure pins. The mechanically limited space in the compensation cylinder can advantageously be changed as a function of the number of pressure bolts used per tool and the sum of the geometric deviation of the functional elements located in the power flow. Another advantage of the solution lies in the fact that although all of the pressure pin points of the pressure pin plate can be occupied by short-stroke cylinders, expediently, only the pressure-pin points necessary according to an empirical determination are occupied by short-stroke cylinders within the framework of the standardized grid. While the number and position of the pressure bolts for each tool are adjusted manually in the known form when the tool is changed, the short-stroke cylinders which are not necessary but are present on the pressure bolt plate can be depressurized and thus switched off communicating system can be disconnected. Likewise, the pressure pin points required for the specific tool can be occupied with pressure pins and the short-stroke pistons of the pressure pin points that are not required can still be operated "blindly". Alternatively, all existing short-stroke cylinders can be operated and only the pressure pin points required for the specific tool can be assigned pressure bolts. The equipment can also be designed so that the individual short-stroke cylinders can be shifted in their assignment to the pressure bolts or removed and retrofitted when the tool is changed. If the number of pressure bolts and / or geometric deviations of the functional elements changes, a volume change in the compensation space in the compensation cylinder is expedient. The short-stroke cylinders can also be designed with different active surfaces.

Die Erfindung soll nachstehend an einem Ausführungsbeispiel näher erläutert werden. Die zugehörigen Zeichnungen zeigen:

Fig. 1:
Prinzipdarstellung der Kraftübertragung zwischen Stößel und Ziehkissen einer mechanischen Presse bei Kontaktbeginn mit zusätzlich angegebener Pressenstößelstellung nach Figur 2.
Fig. 2:
Prinzipdarstellung der Kraftübertragung zwischen Stößel und Ziehkissen einer mechanischen Presse bei Ziehbeginn mit zusätzlich angegebener Pressenstößelstellung nach Figur 1.
Fig. 3:
Draufsicht auf eine Druckbolzenplatte mit Darstellung der Druckbolzenpunkte für verschiedene Werkzeuge
Fig: 4:
Schnitt A - A aus Fig. 3
Der Pressenstößel 1 mit Oberwerkzeug einer mechanischen oder hydraulischen Presse kommt mit dem auf dem Schiebetisch 2 angeordneten Unterwerkzeug in bekannter Weise gemäß Fig. 1 in Wirkverbindung. Zur Verdeutlichung des Zusammenhanges zwischen geometrischer Abweichung und Kraftwirkung der im Kraftfluß liegenden Funktionselemente ist auf die Darstellung von Ober- und Unterwerkzeug verzichtet. Durch Geometrieabweichungen der während des Ziehprozesses im Kraftfluß liegenden Funktionselemente, die sich in der Summe in der Längendifferenz 8, je Druckbolzen 7 mit y₁ bis yn bezeichnet, ausdrücken, kommt es nicht gleichzeitig zum Kontakt aller diesbezüglichen Bauteile. In diesem Ausführungsbeispiel steht die im Pressentisch 4 geführte Druckbolzenplatte 3 in bekannter Weise mit einem auf der Traverse 19 angeordneten Ziehkissen in Wirkverbindung. Dazu wird der Ziehkissenkolben 18 mit der Ziehkissenkraft 23 beaufschlagt. Auf der Druckbolzenplatte 3 sind die Kurzhubzylinder 5 angeordnet, die über Verbindungsleitungen 20 untereinander fließverbunden sind. Jedem Kurzhubkolben 6 ist ein Druckbolzen 7 zuordenbar. Die fließverbundenen Kurzhubzylinder 5 sind über eine Verbindungsleitung 14 mit einem Kompensationsraum 22 eines vorzugsweise starr an der Druckbolzenplatte 3 angeordneten Kompensationszylinders 10 verbunden. Diese Verbindungs-Leitung 14 ist gleichzeitig über ein Wegeventil 17, zu dem ein Druckbegrenzungsventil 24 parallel geschaltet ist, an einer im Kompensationszylinder 10 integrierten Druckmittelbehälter 16 angeschlossen. Über ein Wegeventil 21 steht der Druckmittelbehälter 16 mit einer Druckregulierungseinrichtung 15 in Wirkverbindung. An der mit dem Kompensationskolben 11 starr verbundenen Kolbenstange ist eine verstellbare Hubbegrenzung 13 angeordnet. Vor der Einleitung von Kraft vom Pressenstößel 1 über das Oberwerkzeug in die Druckbolzen 7 befinden sich die Kurzhubkolben 6 in ihrer oberen, mechanisch begrenzten Ausgangsstellung, in die sie durch Federkraft gebracht und gehalten werden. Dabei kann die Feder mechanisch sein oder durch pneumatischen Druck erzeugt werden.The invention will be explained in more detail below using an exemplary embodiment. The associated drawings show:
Fig. 1:
Schematic diagram of the power transmission between the ram and die cushion of a mechanical press at the start of contact with the press ram position specified additionally according to FIG. 2.
Fig. 2:
Schematic representation of the power transmission between the ram and die cushion of a mechanical press at the start of drawing with the press ram position specified additionally according to FIG. 1.
Fig. 3:
Top view of a push pin plate showing the push pin points for different tools
Fig: 4:
Section A - A from FIG. 3
The press ram 1 with the upper tool of a mechanical or hydraulic press comes into operative connection with the lower tool arranged on the sliding table 2 in a known manner according to FIG. 1. In order to clarify the relationship between the geometric deviation and the force effect of the functional elements lying in the force flow, the upper and lower tools are not shown. Geometric deviations of the functional elements lying in the power flow during the drawing process, which are expressed in total in the length difference 8, each pressure pin 7 with y 1 to y n , do not simultaneously result in contact of all relevant components. In this exemplary embodiment, the pressure pin plate 3 guided in the press table 4 is operatively connected in a known manner to a die cushion arranged on the cross member 19. For this purpose, the die cushion piston 18 is acted upon by the die cushion force 23. The short-stroke cylinders 5 are arranged on the pressure pin plate 3 and are flow-connected to one another via connecting lines 20. A pressure pin 7 can be assigned to each short-stroke piston 6. The flow-connected short-stroke cylinders 5 are connected via a connecting line 14 to a compensation chamber 22 of a compensation cylinder 10 which is preferably rigidly arranged on the pressure pin plate 3. This connecting line 14 is simultaneously connected via a directional valve 17, to which a pressure relief valve 24 is connected in parallel, to a pressure medium container 16 integrated in the compensation cylinder 10. The pressure medium container 16 is operatively connected to a pressure regulating device 15 via a directional valve 21. An adjustable stroke limiter 13 is arranged on the piston rod rigidly connected to the compensation piston 11. Before the introduction of force from the press ram 1 via the upper tool into the pressure bolts 7, the short-stroke pistons 6 are in their upper, mechanically limited starting position, into which they are brought and held by spring force. The spring can be mechanical or generated by pneumatic pressure.

Ebenfalls durch Federkraft erzeugt, befindet sich der Kompensationskolben 11 in seiner mechanischen, unteren Endlage. Mit dem Erstkontakt zwischen den antreibenden System von Pressenstößel 1 mit Oberwerkzeug und dem ruhenden Ziehkissen mit der Druckbolzenplatte 3, dem Ziehkissenkolben 18, den Kurzhubzylindern 5 und den Druckbolzen 7 kommt es zur Verschiebung des diesbezüglichen Kurzhubkolbens 6 um den Verdrängerhub 9. Dieser Verdrängerhub 9 ist je Kurzhubzylinder 5 unterschiedlich und mit x₁ bis xn bezeichnet. In der Reihenfolge der jeweiligen Geometrieabweichung bzw. Längendifferenz 8 folgen bis Ziehbeginn alle Druckbolzen 7 und verdrängen Druckmittel über die Verbindungsleitung 20 und 14 in den Kompensationsraum 22 des Kompensationszylinders 10. Durch die Druckmittelverdrängung aus den Kurzhubzylindern 5 erfolgt die Verschiebung des Kompensationskolbens 11 um den Kompensationshub 12. Dieser Kompensationshub 12 und damit die Summe des aus den Kurzhubzylindern 5 verdrängten Druckmittels, wird durch die verstellbare Hubbegrenzung 13 bestimmt. Durch die mechanisch begrenzte Volumenaufnahme im Kompensationszylinder 10 wird der Verdrängerhub 9 der Kurzhubkolben 6 in Ziehrichtung unterbrochen. Damit erfolgt der weitere Antrieb der Druckbolzen gegen die wirkende Ziehkissenkraft 23, die sich über die Traverse 19 am Pressentisch 4 abstützt. Die qualitative Lage der Funktionselemente bei Ziehbeginn ist in Figur 2 dargestellt. Durch die Verbindungsleitung 20 sind alle Kurzhubzylinder 5 zu einem kommunizierenden System zusammengeschlossen, so daß die in Schwimmstellung befindlichen Kurzhubkolben 6 vollen Formschluß der im Kraftfluß liegenden Funktionselemente herstellen und sich dadurch gleicher Druck in allen Kurzhubzylindern 5 einstellt. Diese Wirkung bleibt über den gesamten Ziehhub erhalten. Dabei befindet sich das Wegeventil 17 von der Verbindungsleitung 14 in Richtung Druckmittelbehälter 16 in sperrender Stellung. Parallel zum Wegeventil 17 ist das Druckbegrenzungsventil 24 angeordnet zur Absicherung des Hydrauliksystems vor Überlastung. Zur Realisierung "weicher" Druckübergänge bei Ziehbeginn kann das Wegeventil 17 auch als Stetigventil ausgebildet sein. Mit Entlastung der Druckbolzen 7 nach dem Ziehvorgang erfolgt die Rückförderung des Druckmittels aus dem Kompensationsraum 22 in die Kurzhubzylinder 5, wodurch die Kurzhubkolben 6 ihre Ausgangslage erreichen. Zur Rückführung der Kurzhubkolben 6 und des Kompensationskolbens 11 in ihre Ausgangslage erfolgt die Beaufschlagung des Druckmittels mit Pneumatikdruck über die Druckregeleinrichtung 15 und das Wegeventil 21. Der im Druckmittelbehälter 16 anliegende Druck bewirkt durch die Differenzfläche eine entsprechende Kraft, die den Rückfluß des Druckmittels aus dem Kompensationsraum 22 gewährleistet.Also generated by spring force, the compensation piston 11 is in its mechanical, lower end position. With the first contact between the driving system of press ram 1 with the upper tool and the stationary drawing cushion with the pressure pin plate 3, the drawing cushion piston 18, the short-stroke cylinders 5 and the pressure pin 7, the relevant short-stroke piston 6 is displaced by the displacement stroke 9. This displacement stroke 9 is in each case Short stroke cylinder 5 different and designated x₁ to x n . In the order of the respective geometry deviation or length difference 8, all pressure bolts 7 follow until the start of drawing and displace pressure medium via the connecting lines 20 and 14 into the compensation chamber 22 of the compensation cylinder 10. The pressure piston is displaced from the short-stroke cylinders 5 and the compensation piston 11 is displaced by the compensation stroke 12 This compensation stroke 12 and thus the sum of the pressure medium displaced from the short stroke cylinders 5 is determined by the adjustable stroke limiter 13. Due to the mechanically limited volume absorption in the compensation cylinder 10, the displacement stroke 9 of the short-stroke piston 6 is interrupted in the drawing direction. The pressure bolts are thus driven further against the acting die cushion force 23, which is supported on the press table 4 via the crossmember 19. The qualitative position of the functional elements at the start of drawing is shown in FIG. 2. Through the connecting line 20, all short-stroke cylinders 5 are combined to form a communicating system, so that the short-stroke pistons 6 in the floating position produce full positive locking of the functional elements located in the power flow, and the same pressure is thus set in all short-stroke cylinders 5. This effect is maintained over the entire drawing stroke. The directional control valve 17 is located in the blocking position from the connecting line 14 in the direction of the pressure medium container 16. The pressure relief valve 24 is arranged parallel to the directional control valve 17 to protect the hydraulic system against overload. For realization "Soft" pressure transitions at the start of drawing, the directional control valve 17 can also be designed as a continuous valve. When the pressure bolts 7 are relieved after the drawing process, the pressure medium is returned from the compensation chamber 22 into the short-stroke cylinders 5, as a result of which the short-stroke pistons 6 reach their starting position. To return the short-stroke piston 6 and the compensation piston 11 to their starting position, the pressure medium is acted upon by pneumatic pressure via the pressure control device 15 and the directional control valve 21. The pressure in the pressure medium container 16 causes a corresponding force through the differential area, which causes the pressure medium to flow back from the compensation chamber 22 guaranteed.

Wie aus Figur 3 ersichtlich, besitzt die Druckbolzenplatte 3 eine genormte Anzahl von Druckbolzenpunkten 25. Der Bedarf dieser einzelnen Druckbolzenpunkte 25 je Werkzeug ist bekanntlich sehr unterschiedlich. Neben den Möglichkeiten des Bestückens aller oder der jeweils nur für ein Werkzeug erforderlichen Druckbolzenpunkte 25 mit Kurzhubzylindern 5 wird vorgeschlagen, nach einer empirisch festgestellten notwendigen Druckbolzenpunktebelegung für Werkzeuge in einem bestimmten Zeitraum Kurzhubzylinder 5 zu betreiben und nur die nach jeweiligem Werkzeug erforderlichen Druckbolzenpunkte 25 mit Druckbolzen 7 auszustatten oder die jeweils nicht erforderlichen Druckbolzenpunkte 25 durch "Drucklosschalten" der nicht benötigten Kurzhubzylinder 5 außer Betrieb zu setzen. Dabei ist die Herausnahme der Druckbolzen aus der nicht dargestellten Werkzeugaufspannplatte keine Bedingung. Für den Anwendungsfall "Drucklosschalten" ist jedem Kurzhubzylinder 5 ein Wegeventil 26 und zusätzlich allen Kurzhubzylindern 5 gemeinsam das Wegeventil 27 zugeordnet. Die Wegeventile 26 und 27 sind zwischen den Kurzhubzylindern 5 und dem Druckmittelbehälter 16 angeordnet und in Reihe geschaltet. Sie ermöglichen, daß die für ein Werkzeug nicht benötigten Kurzhubzylinder 5 druckentlastet und damit außer Betrieb gesetzt werden. Bei Bedarf kann die Anzahl der Kurzhubzylinder 5 für jedes Werkzeug angepaßt werden. Dazu sind die Kurzhubzylinder 5 in ihrer räumlichen Anordnung veränderbar bzw. ab- und nachrüstbar. Bei Veränderung der Anzahl der Druckbolzen 7 und/oder der Teilegeometrie bzw. der Längendifferenz 8 ist eine Volumenänderung des Kompensationsraumes 22 mittels der Hubbegrenzung 13 zweckmäßig.As can be seen from FIG. 3, the pressure pin plate 3 has a standardized number of pressure pin points 25. As is known, the need for these individual pressure pin points 25 per tool is very different. In addition to the possibility of equipping all or the pressure pin points 25 required only for one tool with short-stroke cylinders 5, it is proposed to operate short-stroke cylinders 5 in a certain period of time after an empirically determined necessary pressure pin point assignment for tools and only the pressure pin points 25 required for the respective tool with pressure bolts 7 to equip or to deactivate the pressure pin points 25 that are not required by "depressurizing" the short-stroke cylinders 5 that are not required. The removal of the pressure bolts from the platen, not shown, is not a condition. For the "depressurization" application, each short-stroke cylinder 5 is assigned a directional valve 26 and, in addition, all short-stroke cylinders 5 are jointly assigned the directional valve 27. The directional control valves 26 and 27 are arranged between the short-stroke cylinders 5 and the pressure medium container 16 and connected in series. They enable the short-stroke cylinders 5 which are not required for a tool to be relieved of pressure and thus to be put out of operation. If necessary, the Number of short stroke cylinders 5 can be adjusted for each tool. For this purpose, the short-stroke cylinders 5 can be changed in their spatial arrangement or can be retrofitted and retrofitted. When changing the number of pressure bolts 7 and / or the part geometry or the length difference 8, a volume change of the compensation space 22 by means of the stroke limiter 13 is expedient.

Claims (7)

Längenkompensationseinrichtung in einer Klemmeinrichtung zwischen Ober- und Unterwerkzeug einer Presse zum Erreichen der Blechhaltekraft, bei der auf einer Druckbolzenplatte (3) eine Mehrzahl von untereinander fließverbundenen Kurzhubzylindern (5) angeordnet sind, deren Kurzhubkolben (6) jeweils mit Druckbolzen (7) wirkverbunden sind und diese im Zusammenwirken zwischen Ober- und Unterwerkzeug das umzuformende Blech einspannen,
dadurch gekennzeichnet,
daß die Kurzhubzylinder (5) druckmittelseitig mit einem Kompensationszylinder (10) so wirkverbunden sind, daß das vor Ziehbeginn durch Kraftwirkung in den Druckbolzen (7) über den Verdrängerhub (9) in den Kurzhubzylindern (5) verdrängte Druckmittel im Kompensationsraum (22) des Kompensationszylinders (10) aufgenommen wird.Length compensation device in a clamping device between the upper and lower tool of a press to achieve the sheet metal holding force, in which a plurality of short stroke cylinders (5) which are flow-connected to one another and whose short stroke pistons (6) are each operatively connected to pressure pins (7) are arranged on a pressure pin plate (3) and these clamp the sheet metal to be formed in the interaction between the upper and lower tool,
characterized,
that the short-stroke cylinders (5) on the pressure medium side are operatively connected to a compensation cylinder (10) in such a way that the pressure medium in the compensation chamber (22) of the compensation cylinder is displaced by the action of force in the pressure bolts (7) via the displacement stroke (9) in the short-stroke cylinders (5) (10) is added. Längenkompensationseinrichtung nach Anspruch 1,
dadurch gekennzeichnet,
daß für jeden entsprechend der verschiedenen Werkzeuge in einer Werkzeugspannplatte vorhandenen Druckbolzenpunkte (25) jeweils ein Kurzhubzylinder (5) auf der Druckbolzenplatte (3) angeordnet sein kann.Length compensation device according to claim 1,
characterized,
that a short-stroke cylinder (5) can be arranged on the pressure pin plate (3) for each pressure pin point (25) present in a tool clamping plate in accordance with the various tools. Längenkompensationseinrichtung nach Anspruch 1,
dadurch gekennzeichnet,
daß die Kurzhubzylinder (5) in ihrer Anordnung auf der Druckbolzenplatte (3) entsprechend der Werkzeuganforderungen veränderbar sind.Length compensation device according to claim 1,
characterized,
that the short stroke cylinders (5) can be changed in their arrangement on the pressure pin plate (3) according to the tool requirements. Längenkompensationseinrichtung nach den Ansprüchen 1 bis 3,
dadurch gekennzeichnet,
daß jeder Kurzhubzylinder (5) separat drucklos schaltbar ist.Length compensation device according to claims 1 to 3,
characterized,
that each short stroke cylinder (5) can be switched separately without pressure. Längenkompensationseinrichtung nach den Ansprüchen 1 bis 4,
dadurch gekennzeichnet,
daß das Volumen des Kompensationsraumes (22) und damit der Kompensationshub (12) durch eine verstellbare Hubbegenzung (13) veränderbar ist.Length compensation device according to claims 1 to 4,
characterized,
that the volume of the compensation space (22) and thus the compensation stroke (12) can be changed by an adjustable stroke limit (13). Längenkompensationseinrichtung nach den Ansprüchen 1 bis 5,
dadurch gekennzeichnet,
daß die Kurzhubzylinder (5) und der Kompensationszylinder (10) im gleichen Bewegungssystem angeordnet sind und keine Relativbewegung zueinander ausführen.Length compensation device according to claims 1 to 5,
characterized,
that the short stroke cylinder (5) and the compensation cylinder (10) are arranged in the same movement system and do not perform any relative movement to one another. Längenkompensationseinrichtung nach den Ansprüchen 1 bis 6,
dadurch gekennzeichnet,
daß zur Realisierung "weicher" Druckübergänge bei Ziehbeginn das Wegeventil (17) als Stetigventil ausgebildet sein kann.Length compensation device according to claims 1 to 6,
characterized,
that the directional valve (17) can be designed as a continuous valve for realizing "soft" pressure transitions at the start of drawing.
EP95117213A 1994-11-23 1995-11-02 Clamping device between the upper and lower tool of a press Expired - Lifetime EP0713735B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4441562A DE4441562A1 (en) 1994-11-23 1994-11-23 Length compensation device in a clamping device between the upper and lower tool of a press
DE4441562 1994-11-23

Publications (2)

Publication Number Publication Date
EP0713735A1 true EP0713735A1 (en) 1996-05-29
EP0713735B1 EP0713735B1 (en) 1999-01-13

Family

ID=6533869

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95117213A Expired - Lifetime EP0713735B1 (en) 1994-11-23 1995-11-02 Clamping device between the upper and lower tool of a press

Country Status (3)

Country Link
EP (1) EP0713735B1 (en)
DE (2) DE4441562A1 (en)
ES (1) ES2126199T3 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2991608A1 (en) * 2012-06-07 2013-12-13 Peugeot Citroen Automobiles Sa Blank holder for die sinking press, has movable rod connected to cylinder drawn alongside by upper end of candle and part whose position permits to indicate whether cylinder is alongside by candle, where candle is connected to cushion

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0173755A1 (en) * 1984-06-29 1986-03-12 L. SCHULER GmbH Drawing device in a press
FR2667257A1 (en) * 1990-10-02 1992-04-03 Erfurt Umformtechnik Gmbh HYDRAULIC HOLDER FOR SINGLE-EFFECT PRESSES.
EP0531140A1 (en) 1991-09-04 1993-03-10 Toyota Jidosha Kabushiki Kaisha Hydraulic cushioning system for press, having hydraulic power supply including means for adjusting initial pressure to pressure-pin cylinders
EP0531141A1 (en) * 1991-09-04 1993-03-10 Toyota Jidosha Kabushiki Kaisha Hydraulic cushioning system for press, having shut-off valve for disconnection of pressure-pin cylinders from power supply upon contact of movable die with workpiece
EP0565347A2 (en) * 1992-04-07 1993-10-13 Toyota Jidosha Kabushiki Kaisha Method and apparatus for measuring blank holding force acting on pressure ring of a press
EP0596696A1 (en) * 1992-11-05 1994-05-11 Toyota Jidosha Kabushiki Kaisha Method and device for controlling, checking or optimizing pressure of cushion pin cylinders of press by discharging fluid or initial pressure

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3735581C1 (en) * 1987-10-21 1988-05-11 Daimler Benz Ag Press for pulling sheet metal parts

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0173755A1 (en) * 1984-06-29 1986-03-12 L. SCHULER GmbH Drawing device in a press
FR2667257A1 (en) * 1990-10-02 1992-04-03 Erfurt Umformtechnik Gmbh HYDRAULIC HOLDER FOR SINGLE-EFFECT PRESSES.
EP0531140A1 (en) 1991-09-04 1993-03-10 Toyota Jidosha Kabushiki Kaisha Hydraulic cushioning system for press, having hydraulic power supply including means for adjusting initial pressure to pressure-pin cylinders
EP0531141A1 (en) * 1991-09-04 1993-03-10 Toyota Jidosha Kabushiki Kaisha Hydraulic cushioning system for press, having shut-off valve for disconnection of pressure-pin cylinders from power supply upon contact of movable die with workpiece
EP0565347A2 (en) * 1992-04-07 1993-10-13 Toyota Jidosha Kabushiki Kaisha Method and apparatus for measuring blank holding force acting on pressure ring of a press
EP0596696A1 (en) * 1992-11-05 1994-05-11 Toyota Jidosha Kabushiki Kaisha Method and device for controlling, checking or optimizing pressure of cushion pin cylinders of press by discharging fluid or initial pressure

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2991608A1 (en) * 2012-06-07 2013-12-13 Peugeot Citroen Automobiles Sa Blank holder for die sinking press, has movable rod connected to cylinder drawn alongside by upper end of candle and part whose position permits to indicate whether cylinder is alongside by candle, where candle is connected to cushion

Also Published As

Publication number Publication date
ES2126199T3 (en) 1999-03-16
EP0713735B1 (en) 1999-01-13
DE59504805D1 (en) 1999-02-25
DE4441562A1 (en) 1996-05-30

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