EP1344585B1 - Hydroelastic deep drawing device - Google Patents

Abstract

The deep drawing device has several force effect fields round one or more drawing punches (5), with each separate force effect field having a fixed integrated short-stroke cylinder system, consisting of a short-stroke cylinder (9) and a short-stroke piston (10), to which a spacer (11) is attached carrying one or more form bolts (15).

Description

The invention relates to a hydro-elastic deep-drawing device for drawing sheet metal parts according to the preamble of claim 1. Such a device is known from DE-A-19641411 known.

In metal forming for the production of deep-drawn sheet metal parts, it is part of the system of tool technology that are used to support the sheet holder plates pulling pins. These pull pins acting as spacer pins are push pins between the blank holder plate and the die cushion. They are a necessary component of the respective thermoforming tool, that is, the length of the drawing pins and their number is tool-related.

As.Nachteilig these mechanical pull pins has been found that they wear and thus uneven Blechhaltekräfte set with rigid hold-down system during operation uncontrollably can, which causes an uncontrolled wrinkling of the molded part. Elastic hold-downs can prevent this effect by interposing a rubber plate.

From the DE-PS 30 22 844 is already a thermoforming of tools or presses for drawing sheet metal parts known, which has a plurality of pressure cylinders and in this axially movable guided, acted upon by flow pressure piston piston for supporting a sheet holder plate and with another, a movable in the drawing direction drawing die receiving Cushions is equipped, the pressure cylinder connected to the pressure cylinders of the sheet holder support die cushion connected via flow paths and the drawing process from these pressure cylinders displaced flow pressure means are acted upon.

Of importance in this thermoforming device is that when depressing the operated by a press ram drawing ring from the printing cylinders of the sheet holder support die cushion flowing pressure medium via lines in the pressure cylinder of the other die cushion, on which the drawing punch is received vertically movable, flows over and in the pressure cylinders this drawing pad guided piston guided, which in turn during the drawing process the drawing punch against the direction of movement of the drawing ring and the blank holder plate in the pulling direction. This thus realized direct flow network between the pressure cylinders of the sheet holder plate field of effect to the pressure cylinders of the drawing punch field of action is intended to represent a so-called pressure balance.

Part of the disadvantages of mechanical drawing pins could be avoided with this known thermoforming device. A disadvantage of this thermoforming device has nevertheless been found:
The resulting forces are not reproducible, because a dependence between the pull rate due to different flow resistance arise, that is, for a process control on a computer system, it is not suitable. The flow of forces during sheet metal forming is more or less parabolic from the beginning to the end of the deep-drawing process. Especially in the case of flat drawn parts or even in the case of complicated shaped part geometries, it is absolutely necessary, at the beginning, to control higher sheet metal holding forces in specific areas of the blank holder area.

To compensate for this disadvantage is then after DE-OS 33 33 687 a pressure control valve has been included to flow through the flow of hydraulic oil between the blank holder and drawing punch on this Pressure control valve, for example, at the beginning or basically over the Gesamtziehverlauf to be able to set different pressures.

1. a) Bei unterschiedlichen Druckzuständen im Wirkungsfeld-Blechhalter und Wirkungsfeld-Ziehstempel wird das Öl unterschiedlich komprimiert, wodurch hydraulische Druckspitzen verursacht werden, welche wieder zur Zerstörung der Schmierfilmoberflächenstruktur führen können.
2. b) Das Drucksteuerventil hat einen Lecköl-Verbrauch.
3. c) Aufgrund der Verhältnisse gemäß a) und b) sind keine reproduzierbaren Prozess- bzw. Produktionsabläufe erzielbar, das heißt eine exakte Prozessführung ist nicht möglich und
4. d) Bei der Herstellung von einfachen Einzelbecken mit gleichmäßigem Rand ist diese Art der Tiefzieheinrichtung zu teuer.

The following disadvantages of this thermoforming device and its control have been found in practice:

1. a) At different pressure conditions in the field effect sheet holder and field effect drawing punch, the oil is compressed differently, causing hydraulic pressure peaks, which can again lead to the destruction of the lubricating film surface structure.
2. b) The pressure control valve has a leakage oil consumption.
3. c) Due to the conditions according to a) and b) no reproducible process or production processes are achievable, ie an exact process control is not possible and
4. d) In the case of the production of simple individual basins with a uniform edge, this type of thermoforming device is too expensive.

Due to the composite flow in the two named rights is generally still the disadvantage that the drawing punch-Wegposition, due to the oil compressibility and leaks, not exactly reproducible is controlled.

With DE 196 41 411 A1 a hydraulic deep-drawing device has been known in presses for drawing sheet metal parts, in which the holding force for deep drawing on an outer and an inner knuckle is constructed. In this case, the outer ring gear is acted upon by an adjustable base load, wherein the mold bolts of the inner active ring act on the sheet metal plate and each individually or in groups targeted controlled acted upon. The arrangement of a multi-point unit in this selected form has basically proven, but has the disadvantage that with such a multi-point unit, the eccentric load of the Kurzhubkolben-cylinder units with very high pressures is not possible.

The object of the present invention has been made to realize while avoiding the disadvantages mentioned a computer-aided, process-capable, hydroelastic deep drawing, in which the according to the shape geometry of the workpiece arranged pressure cylinder piston assemblies for the sheet holder plate field of action to activate and with an exact force profile control without disturbance amplitudes to achieve the benefits and effects of a rubber-elastic Ziehkissenystems; Furthermore, the task is to be able to transmit larger forces via a cylinder and this even if additional larger eccentric loads per cylinder unit occur, as well as to create a simple and inexpensive thermoforming device.

1. a) ein gegenüber den Kurzhubzylindern (9) großflächiges und lang ausgeführtes Distanzstück (11) kippsicher abgestützt ist,
2. b) dazu das Distanzstück (11) in der Tischplatte (6) oder im Stößel (8) kippsicher geführt ist auf dem Distanzstück (11) der zumindest einem Form bolzen (15) auf die Blechhalteplatte (12) zentrisch oder exzentrisch andrückbar angeordnet ist, und
3. c) die Kurzhubkolben (10) und ihre Distanzstücke (11) in ihrem Durchmesser oder nach Ihren Wirkflächen annähernd in der Größe der Umgrenzung der Kraftwirkungsfelder entsprechend ausgeführt sind.

The solution of this problem is realized according to the teaching of the characterizing part of claim 1, characterized in that:

1. a) a short distance from the short-stroke cylinders (9) large and long executed spacer (11) is supported tip over,
2. b) to the spacer (11) in the table top (6) or in the plunger (8) is guided tilt-proof on the spacer (11) of the at least one shape bolt (15) on the plate plate (12) is arranged centrically or eccentrically pressed, and
3. c) the Kurzhubkolben (10) and their spacers (11) are executed in their diameter or according to their effective areas approximately in the size of the boundary of the force action fields accordingly.

The stationary embodiment of the thermoforming device according to the invention is in particular conceptually simpler and thus less expensive than thermoforming forming presses with a mobile die cushion plate or a multipoint drawing cushion. The Kurzhubkolbenzylindersysteme work per force field in a stationary arrangement low-noise and reliable. This also applies to stationarily arranged mating cylinder for the drawing punch movement.
The measures and features of the invention, it is also particularly successful for several fields of action of the blank holder plate to understand the process advantage of a rubber-elastic blank holder die cushion system, but with the advantage and the possibility of computer-aided process control, the control of the Kurzhubkolben-cylinder systems for the force action fields both the same as well as with different pressure depending on the molding, is possible.

The arrangement of the Kurzhubkolben-cylinder systems in the table top or below the table top can be carried out an exemption of the molded part from the drawing punch for safe removal of molded parts. The arrangement of Kurzhubkolben cylinder action fields in kinematic Inversion also allows a vertical clearance within the press between the ram and table top, because the accommodation of the Kurzhubkolben-cylinder systems is within the necessary clearance for the Ziehstempelhub. The ram force can be used as a base load acting on the drawing ring advantageous for a tilt-free force of the Kurzhubkolben-cylinder systems. As a result, a trouble-free process control in the independent hydraulic pressure action of the short-stroke force action fields is given advantageous.

The hydraulic deep-drawing device according to the invention in combination with the short-stroke piston-cylinder system can be used with advantages both in hydraulic and in mechanical (crank) deep-drawing presses.

Another advantage is:

Each spacer with the associated short-stroke piston is supported on the basis of the force action field on a large hydraulic cushion, so that unevenness on the draw ring automatically with the effect of a rubber-elastic die cushion, a uniform force around the drawing ring, are compensated. For each force action field for a Kurzhubkolben cylinder system is assigned, the arrangement of the force action fields can be chosen arbitrarily, which are required according to the drawing ring geometry and the tool and the force action fields with Regard to an exact force profile control over the pulling stroke servo-hydraulically controlled.

Depending on the tool requirement, each path position is controlled in a position-controlled manner and a parallel provision of the blank holder plate after the deep-drawing operation is achieved. The return stroke can be carried out at high speed, after a pre-programmable velocity profile (acceleration and deceleration) for demolding the drawn part.
The advantage here is that the large-scale Kurzhubkolben cylinder arrangements automatically compensate for control errors in the synchronous drive. It is also advantageous that the short-stroke piston-cylinder arrangement are controlled servohydraulically with high precision and low costs with a small volume of oil, virtually no compression volume, for rapid movements.

With the thermoforming device according to the invention, the possibility is created to use existing tools that were previously used for mechanical drawing pins, even on this hydraulic thermoforming universal without modification, with the possibility of a very high process capability of servohydraulic control and the use of different process steps, for Example switching from normal Deep-drawing process to counter-run, a very good range of applications allows.

The possibilities of the process capability of the method for controlling the deep-drawing process are particularly important for the quality assurance of the deep-drawn part to be produced. Interference, such as tilting of the press ram or non-parallelism of the tool can be effectively compensated by the specified hydraulic Kurzhubkolben-cylinder system, for example, to prevent wrinkles preventively.

The other claims relate to expedient embodiments of the subject matter of the invention.

The invention is illustrated below with reference to embodiments in the drawing and will be described in more detail below.

Figur 1

in schematischer Darstellung die Tiefzieheinrichtung nach der Erfindung,

Figur 2

eine Draufsicht auf die Tischplatte nach Figur 1 mit eingezeichneten möglichen Beckengeometrien,

Figur 3

die Ausbildung eines erfindungsgemäßen Kurzhubkolben-Zylindersystems im Detail nach einem Ausschnitt "A" aus Figur 1,

Figur 4

zwei beispielhafte Anordnungen der Formbolzen auf den Distanzstücken in der Führungsplatte,

Figur 5

ein zweites Ausführungsbeispiel der Tiefzieheinrichtung gemäß der Erfindung mit stationärem Kurzhubkolben-Zylindersystem in der Tischplatte und

Figur 6

ein drittes Ausführungsbeispiel der Tiefzieheinrichtung gemäß der Erfindung mit im Stössel integrierten Kurzhubkolben-Zylindersystemen beim Einsatz als zweifach wirkende Presse oben.

Show it:

FIG. 1

a schematic representation of the thermoforming device according to the invention,

FIG. 2

a plan view of the table top after FIG. 1 with possible pelvic geometries,

FIG. 3

the formation of a Kurzhubkolben-cylinder system according to the invention in detail after a section "A" from FIG. 1 .

FIG. 4

two exemplary arrangements of the forming bolts on the spacers in the guide plate,

FIG. 5

a second embodiment of the thermoforming device according to the invention with a stationary Kurzhubkolben-cylinder system in the table top and

FIG. 6

a third embodiment of the thermoforming device according to the invention with integrated in the ram Kurzhubkolben-cylinder systems when used as a double-acting press top.

1. a) Kipplagen mit unterschiedlichen Winkellagen durch Schrägstellung des Stössels 8 können nicht auftreten, wenn die Stösselkonstruktion bzw. - bewegung so ausgeführt ist, dass sich der Stössel 8 zwangsläufig flächig auf die Ziehringplatte 4 abstützt und
2. b) die Anordnung der Kurzhubkolben-Zylindersysteme 20 kann in entsprechender Grösse und gleicher Weise zu Kraftwirkungsfeldern ausgeführt werden, ebenso die Aufteilung in verschiedene Kraftwirkungsfelder.

The drawing shows in the FIGS. 1 . 5 and 6 three embodiments of the thermoforming device in a press 1, wherein the table top 6 is arranged in the press frame 2 below and the plunger 8 from top to bottom for the closure and opening of the press room and for fixing the workpiece 7 on the sheet holder plate 12 or on the drawing ring. 4 serves. A Kurzhubkolben-cylinder system 20 consists of the Kurzhubzylinder 9, the short-stroke piston 10, the spacer 11 and supported one or more, executed according to the drawing ring geometry mold bolt 15, wherein they are supported centrally or eccentrically on the large-area spacer 11 and guided in the guide plate 19 are. The stationary arrangement of the short-stroke piston cylinder system 20 below, in the table top 6 or in the outer tappet 8, allows the use of one or more hydraulic drawing punches 5, which perform by means of a hydraulic piston 3 a drawing punch movement from bottom to top or from top to bottom in the vertical direction. In these arrangements can thus be advantageously used a simple top piston press, with the advantage:

1. a) tilting plies with different angular positions by tilting the plunger 8 can not occur if the plunger construction or - movement is carried out so that the plunger 8 is necessarily supported on the flat Ziehringplatte 4 and
2. b) the arrangement of the Kurzhubkolben cylinder systems 20 can be performed in a corresponding size and the same way to force action fields, as well as the division into different force action fields.

The diameter of the short-stroke cylinder 9 and the short-stroke piston 10 with the spacers 11 are executed in size and effective area approximately corresponding to the existing boundary of the force action fields. To FIG. 5 for the ram is divided into two parts in an outer ram 8 with the sheet metal holder plate 12 and an inner plunger, which acts as a drawing punch 13 with its own drive executed. In the context of the invention, the first Embodiment after FIG. 1 considered to be advantageous in which the drawing punch acts upward.

The Figures 5 and 6 show a variation in the arrangement of the Kurzhubkolben-cylinder systems 20 in the upper plunger 8, for example, when used as a double-acting press 1 from above, the arrangement of the Kurzhubkolben 10 also according to the force action fields structured with larger Kurzhubkolben 10 Kurzhubzylindern 9 is executed.

The FIG. 2 shows a plan view of the table top 6 after FIG. 1 , with the Kurzhubkolben-cylinder systems 20, the drawing punch 5 and the workpiece 7. With 21 several variants of the producible pelvic geometries are located.

The enlarged view of a Kurzhubkolben-cylinder system 20 is in the FIG. 3 shown. It shows the short-stroke piston 9 integrated in the table top 6 and guided in seals 17 and in guide rings 18. However, the power transmission to the forming bolt 15 takes place via a long guide 11 in a guide bushes 16 guided long distance piece 11 with hardened wear plate 14. The forming bolt 15 can rest with an eccentricity L to the central axis on the wear plate 14. If necessary, two or more mold bolts 15 may be provided.

The short-stroke cylinder 9 is about 200 to 250 mm in diameter larger than the previously executed short-stroke cylinder and therefore can also generate forces up to 80 to. Likewise, the support for the forming bolt 15 with a diameter of about 300 mm larger than the conventional short-stroke cylinder 9 and thus leaves more scope for the positioning of the forming bolt 15. Due to the large guide length of the spacer 11 can also 80 tons at this eccentric load be handled without tilting.

In FIG. 4 are still the possible arrangements illustrated with the shape of the forming bolt 15 on the spacer 11. If necessary, the mold bolt 15 can also be designed as an angle iron.

LIST OF REFERENCE NUMBERS

1.

Press

Second

press frame

Third

Hydraulic piston for drawing punch 5 integrated in tabletop or plunger plate

4th

drawing ring

5th

drawing punch

6th

tabletop

7th

workpiece

8th.

tappet

9th

Short stroke cylinder (integrated in table or ram)

10th

Short-stroke piston (integrated in table or ram)

11th

spacer

12th

Sheet holding plate

13th

Drawing stamp in the plunger

14th

wear plate

15th

shaping pins

16th

guide bush

17th

seals

18th

guide ring

19th

guide plate

20th

Short-stroke piston-cylinder system

21st

Variants of the manufacturable pelvic geometries

Claims (12)

1. A hydro elastic deep drawing device for drawing sheet-metal formed parts, comprising a sheet holding plate (12) supported against hydraulic pressure cylinders and pressure pistons and a drawing stamp (5) movably guided in the drawing direction which rests on at least one piston guided in a cylinder and pressurized with hydraulic medium and a punch (8) which is guided upwardly and downwardly movable in the upper head, with several force effect fields which can be chosen with regard to their number and surface area being provided round one or more drawing punches (5) for the hydro elastic deep drawing device for pressing the sheet holding plate (12), with each force effect field being associated with a fixed integrated short-stroke cylinder system consisting of short-stroke cylinder (9) and short-stroke piston (10) with at least one associated form bolt (15), characterized in that

   a) a spacer element (11) which has a large surface area and is provided with a long configuration is supported in a tilt-proof manner relative to the short-stroke cylinders (9);

   b) in addition the spacer element (11) is guided in a tilt-proof manner in the table board (6) or in the punch (8) and at least one form bolt (15) is arranged on the spacer element (11) which can be pressed on the sheet holding plate (12) in a centric or eccentric manner, and

   c) the short-stroke pistons (10) and their spacer elements (11) are arranged accordingly in their diameter or according to their effective surfaces approximately in the size of the delimitation of the force effect fields.
2. A hydro elastic deep drawing device according to claim 1, characterized in that an adjustment to similar work pieces (7) of a family of parts is possible as a result of the different arrangement of the form bolts (15) on the effective surfaces of the spacer elements (11).
3. A hydro elastic deep drawing device according to claim 1 or 2, characterized in that the tilt-proof guidance of the spacer elements (11) in the table board (6) or in the punch (8) is ensured by two guide bushes (16).
4. A hydro elastic deep drawing device according to one or several of the claims 1 to 3, characterized in that the spacer elements (11) have a wearing plate (14) on the side of the form bolts (15).
5. A hydro elastic deep drawing device according to one or several of the claims 1 to 4, characterized in that the short-stroke cylinders (9) have a diameter of 200 to 250 mm.
6. A hydro elastic deep drawing device according to one or several of the claims 1 to 5, characterized in that the spacer elements (11) have a diameter of 300 mm.
7. A hydro elastic deep drawing device according to one or several of the claims 1 to 6, characterized in that the form bolts (15) are arranged in adjustment and according to the associated drawing die shape.
8. A hydro elastic deep drawing device according to one or several of the claims 1 to 7, characterized in that the drawing punch(es) (5) is/are arranged in a stationary manner within or beneath the table board (6) by acting upwardly from below.
9. A hydro elastic deep drawing device according to one or several of the claims 1 to 8, characterized in that the drawing punch(es) (5) is/are arranged in a stationary manner within the bipartite punch (8) by acting downwardly from above.
10. A hydro elastic deep drawing device according to one or several of the claims 1 to 9, characterized in that the short-stroke piston cylinder systems (20) are arranged in the table board (6) in a stationary manner.
11. A hydro elastic deep drawing device according to one or several of the claims 1 to 10, characterized in that the short-stroke piston cylinder systems (20) are arranged in the outer punch (8) in a stationary manner.
12. A hydro elastic deep drawing device according to one or several of the claims 1 to 11, characterized in that each force effect field can be triggered in a hydraulic manner independent from the others by a short-stroke piston cylinder system (20).

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