EP1106275B1 - Apparatus for high pressure forming of a tubular member or blank - Google Patents

Abstract

The device has a forming tool (2) with upper and lower forming dies (4,3). The upper forming tool is coupled via a piston-cylinder-unit (9) containing a hydraulic fluid, to a press ram (12) of a mechanical press, so as to be relatively moveable to a limited degree. The cylinder chamber (19) of the unit is in fluid-connection with the inner chamber of the tubular part (BT). Alternatively, the cylinder chamber is similar connected to the forming chamber of the forming tool.

Description

The invention relates to a device for hydraulic Hydroforming according to the preamble of claims 1 and 2 (see e.g. DE-A-197 05 244).

For the hydraulic forming of a tubular component it is known to place the component in an initially open mold from upper die and lower die to lay it with fill liquid active medium and over the component ends To seal sealing mandrels. After closing the Hydraulic pressure in the component built up to the component the given contours in To deform the mold accordingly.

This is based on a hydraulic locking press, the control is designed so that it during the hydroforming process, the mold over a longer period Time holds up. The hold time is e.g. for chassis components, like side members and cross bridges, in the area from 5 to 10 seconds. This then results in cycle times in the range of about 30 to 40 seconds to manufacture every finished part including the transport of the component to be deformed into the mold and the removal of the deformed component from the mold.

The invention is based on the prior art Task based on a device for hydraulic High pressure forming of a tubular component or one To create circuit board that with easy integration in a bound mechanical press is structurally simple designed and easy to use.

According to the invention, this object is achieved in the features of claim 1 and claim 2.

The invention advantageously combines a molding tool with lower die and upper die for hydraulic Internal high pressure forming of tubular components or for hydraulic high pressure forming of blanks with a tied mechanical press, as in the form of a Eccentric, crank or toggle press is known.

A characteristic feature of such a mechanical Press is the continuous movement in continuous operation. On the other hand, this requires high pressure forming an absolutely closed one during the forming process Forming tool with sufficient over the period of forming Clamping force. These two contrary requirements the invention takes into account that Upper die of the mold over at least one Piston-cylinder unit containing hydraulic fluid the press ram of a mechanical press is relatively limited is movably coupled. Because of one The piston-cylinder unit becomes a hydraulic cushion created between the upper die and the press ram. This hydraulic cushion then allows one Decoupling of the continuous plunger movement from the Molding tool for the time of high pressure forming a tubular component or a circuit board in the area of bottom dead center. At the same time, the piston-cylinder unit used in the piston-cylinder unit contained fluid immediately for forming the component or to use the circuit board. This is the cylinder the piston-cylinder unit with the interior of the component or fluid-conducting with the molding space of the molding tool connectable. Because of this, a separate Pressure intensifier and associated hydraulic units and components are eliminated.

The advantages of the training according to the invention are one significant reduction in cycle times, a reduction the investment costs for the components for pressure generation as well as a significantly reduced control effort. In addition, there is the great advantage that the existing mechanical capacities in one company Presses for high pressure forming in particular tubular components to be formed from small series sizes or boards can be used.

Depending on the type and shape of the contour to be reshaped tubular component or a circuit board becomes only one Piston-cylinder unit or multiple piston-cylinder units between the upper die and the press ram incorporated. Especially the arrangement of several smaller piston-cylinder units along one Component or board contour and direct hydraulic Connection in which the piston area of the projected Surface of the component or the board corresponds, can ensure that at every moment of forming a balance of forces between the piston-cylinder units and the component or the circuit board prevails. With this arrangement, the other advantage achieved elastic deformations in the mold be minimized, resulting in improved manufacturing accuracy leads.

A tubular component can be filled with conventional components Hydraulic units take place. Is conceivable but also a variant in which a filling of the Component is carried out in a plunge pool.

Since the piston-cylinder unit as a separate, both from Upper tool and device separable from the press ram trained, it can with flexible design for different molds and mechanical Presses are used.

An advantageous development of the invention consists in the features of claim 3, according to which the piston the piston-cylinder unit via a piston plate on the Press ram and the cylinder over a cylinder plate are releasably attached to the upper die. The piston plate also indicates your assigned return means on that with the cylinder or the cylinder plate relative are movably connected. These return means can for example consist of guide rods, which consoles relatively movable on the cylinder or on the cylinder plate enforce and provide driving heads at the free end are that under the consoles or the cylinder plate grasp and during the upward movement of the press ram the cylinder or the cylinder plate and thus raise the upper die.

Is according to claim 4 in a line between the piston-cylinder unit and the mold a fluid separator incorporated, so in the area of the piston-cylinder unit advantageously a hydraulic oil, if necessary applied with suitable additives and for Forming a tubular component or a blank uses an aqueous fluid with only minor lubrication additives become. In this context, it may be be expedient, the fluid separator as a pressure intensifier with a low gear ratio. Because of this, there is additional freedom in the design and adaptation of the piston-cylinder unit to a tubular component or to a Circuit board.

To fully adapt a tubular when reshaping Component or a board to the mold space ensure the piston-cylinder unit is designed so that the volume displaced by it is larger than what would be required for forming. To this excess Taking up volume is according to claim 5 a line between the piston-cylinder unit and the Mold a pressure coaster with subordinate Pressure relief valve connected. That on the low pressure side of the pressure reducer arranged pressure relief valve causes that to determine only when one reaches Internal pressure in the component or in the mold space that of the piston-cylinder unit displaced volume over the Pressure intensifier is discharged. That particular pressure corresponds to the pressure required to completely fill out the Form space through the component or adaptation of the board the contours of the molding space is required. Such one Solution of the pressure or volume limitation is due the very high pressures that occur in hydroforming in the range 600 bar to 3000 bar advantageous because for this application has a direct pressure limitation through commercially available Pressure limiter is not possible.

Figuren 1 bis 3

im vertikalen Längsschnitt im Schema eine mechanische Presse zum Innenhochdruckumformen eines rohrförmigen Bauteils in verschiedenen Betriebsstellungen;

Figur 4

eine Darstellung ähnlich derjenigen der Figuren 1 bis 3 gemäß einer weiteren Ausführungsform und

Figur 5

einen schematischen Querschnitt durch die Darstellung der Figur 4 entlang der Linie V in Richtung der Pfeile Va.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. Show it:

Figures 1 to 3

in the vertical longitudinal section in the diagram a mechanical press for the internal high pressure forming of a tubular component in different operating positions;

Figure 4

a representation similar to that of Figures 1 to 3 according to another embodiment and

Figure 5

a schematic cross section through the representation of Figure 4 along the line V in the direction of arrows Va.

In Figures 1 to 3, 1 is generally a device for hydraulic hydroforming of a tubular Component called BT. The device 1 comprises a mold 2 with a lower die 3 and an upper die 4. The lower die 3 is on the press table 5 a bound mechanical press 6 in Form of a crank press releasably set. The upper die 4 is a cylinder plate 7 with the cylinder 8 one Piston-cylinder unit 9 releasably connected. The piston 10 the piston-cylinder unit 9 is via a piston plate 11 with the press ram 12 of the mechanical press 6 releasably connected.

Furthermore, FIGS. 1 to 3 show that the Cylinder plate 7 rod-shaped return means 13 attached are the holes 14 in the cylinder plate 7th grasp relatively flexibly. At the free end, the Return means 13 driving heads 15.

To maintain the graphic clarity in Figures 1 to 3 all conventional hydraulic units not shown for the operation of the Device 1 are required. Just a line 16 between the piston-cylinder unit 9 and the Mold 2 is indicated schematically by its special training also a relative shift of the Piston-cylinder unit 9 to form tool 2 allowed. In addition, there is a feed line 17 for the one causing the deformation Forming fluid and a check valve 18 shown.

The forming process of a component BT runs approximately as follows from:

According to the illustration in FIG. 1, the press ram is located 12 together with the upper die 4 in the top dead center the press 6. The driving heads 15 of the return means 13 grip under the cylinder plate 7. Forming fluid is via lines 17 and 16 in the cylinder chamber 19th the piston-cylinder unit 9 and filled in the component BT.

By turning the crank, not shown in detail the press ram 12 is moved downward.

Device 1 shows the situation according to FIG closed mold 2. The crank of the press 6 has but has not yet reached bottom dead center.

As a result, the press ram 12 is moved further downward, whereby with the mold 2 closed by means of of the piston 10 forming fluid from the cylinder chamber 19 of the Piston-cylinder unit 9 via line 16 in the component BT is transferred so that due to the the pressure loading the forming fluid begins, according to the figure 3 in the mold space 20 of the mold 2 to deform. The check valve 18 prevents the Umformfluids.

If the crank has reached bottom dead center according to FIG. 3, the forming of the component BT has ended.

Now the crank, which continues to rotate, begins the press ram 12 to raise again. The molding tool 2 remains still closed. The press ram 12 moves relatively to the cylinder 8 of the piston-cylinder unit 9 upwards. The rod-shaped return means 13 slide through the cylinder plate 7.

Reach the driving heads 15 of the return means 13 Cylinder plate 7, the further upward movement of the Press ram 12 also the cylinder 8 of the piston-cylinder unit 9 and about the cylinder plate 7 that too Upper die 4 raised.

Is between the upper die 4 and the lower die 3 If the distance is sufficiently large, the formed one can Component BT against a new component BT to be reformed be replaced.

The crank of the press 6 has the top dead center again reached, a forming cycle has ended.

Figures 4 and 5 show a device 1a for hydraulic high pressure forming of a tubular Component BT, in which an upper die 4a of a mold 2a over a total of three containing a hydraulic fluid Piston-cylinder units 9a with a press ram 12a of a bound mechanical press 6a in The shape of a crank press can be coupled with limited mobility is. The pistons are also in this embodiment 10a of the piston-cylinder units 9a via a piston plate 11a releasably connected to the press ram 12a, whereas the cylinders 8a of the piston-cylinder units 9a via a cylinder plate 7a with the upper die 4a of the Mold 2a are releasably connected. The lower die 3a of the molding tool 2a is on a die plate 21 the press table 5a of the mechanical press 6a releasably attached. It is also shown that the Lower die 3a with the die plate 21 in a drip pan 22 for the forming fluid.

The piston plate 11a has rod-shaped return means 13a, which bores 14a in the cylinder plate 7a grasp relatively movable and on the free Have ends of driving heads 15a. The driving heads 15a lie as in the embodiment of FIGS. 1 to 3 next to the upper die 4a.

The cylinder spaces 19a of the piston-cylinder units 9a are connected to a fluid separator 24 via a line 23. Located in the housing 25 of the fluid separator 24 an axially displaceable piston 26, which in fluid located in the cylinder spaces 19a, e.g. on Hydraulic oil, from the forming fluid, for example with Water provided with lubricants, separates.

The fluid separator 24 is via a line 27 and a line 28 is connected to the molding tool 2a. The on the molding tool 2a connected line 28 protrudes a check valve 29 with a switching valve 30 in connection, which in turn is connected to a feed line 31 for the Forming fluid is connected.

There is also a line 28 to the molding tool 2a Line 32 connected to a pressure reducer 33 leads. The pressure reducer 33 is on the other hand a line 34 connected to a check valve 35, that is in front of a switching valve 36, which is in the feed line 31 is incorporated. To line 34 between check valve 35 and pressure reducer 33 a pressure relief valve 37 is connected, on the other hand via a line 38 with one not closer illustrated reservoir is connected.

For a complete shaping of the component to be formed Ensure BT in the mold space 20a of the mold 2a must be the piston-cylinder units 9a displaceable volume may be greater than the volume resulting in Forming is needed. The excess displaced Volume is then fed to the pressure reducer 33. Whose Piston 39 shifts to the left. At a predetermined Pressure required to completely fill the mold space 20a is necessary, this occurs in the larger room 40 of the pressure reducer 33 located forming fluid the pressure relief valve 37 in the reservoir about.

FIG. 5 clearly shows the distribution of the piston-cylinder units 9a along the in the embodiment in the top view trapezoidal curved component BT.

REFERENCE NUMBERS

1 -

contraption
1a - device

2 -

Molding tool v. 1
2a - mold v. 1a

3 -

Lower die v. 2
3a - lower die from 2a

4 -

Upper die v. 2
4a - upper die v. 2a

5 -

Press table v. 6
5a - press table v. 6a

6 -

Press
6a - press

7 -

cylinder plate
7a - cylinder plate

8th -

Cylinder v. 9
8a - cylinder from 9a

9 -

Piston-cylinder unit
9a - piston-cylinder units

10 -

Piston v. 9
10a - piston from 9a

11 -

piston plate
11a - piston plate

12 -

press ram
12a - press ram

13 -

return means
13a - return means

14 -

Holes in 7
14a - holes in 7a

15 -

Take-away heads on 13
15a - Take away heads on 13a

16 -

Line between 9 a. 2

17 -

Supply line to 16

18 -

check valve

19 -

Cylinder space v. 9
19a - cylinder rooms from 9a

20 -

Formraum v. 2
20a - Formraum v. 2a

21 -

die plate

22 -

drip tray

23 -

Line between 19a and 24

24 -

fluid separator

25 -

Housing v. 24

26 -

Piston v. 24

27 -

Line between 24 and 28

28 -

Line between 29 a. 2a

29 -

check valve

30 -

switching valve

31 -

feed

32 -

Line between 28 and 33

33 -

Pressure reducer

34 -

Line between 3 and 35

35 -

check valve

36 -

switching valve

37 -

Pressure relief valve

38 -

management

39 -

Piston v. 33

40 -

Room v. 33

BT -

component

Claims (5)

1. A device for the hydraulic internal high-pressure forming of a tubular component (BT) in a forming tool (2, 2a) comprising a bottom die (3, 3a) and a top die (4, 4a), wherein the top die (4, 4a) is coupled for limited relative movement, via at least one piston and cylinder unit (9, 9a) containing a hydraulic fluid, to the ram (12, 12a) of a distance-dependent mechanical press (6, 6a), characterised in that the cylinder chamber (19, 19a) of the piston and cylinder unit (9, 9a) is connected in fluid conductive manner to the interior of the component (BT).
2. A device for the hydraulic high-pressure forming of a plate in a forming tool (2, 2a) with a forming chamber (20, 20a) defined by a bottom die (3, 3a) and a top die (4, 4a), wherein the top die (4, 4a) is coupled for limited relative movement, via at least one piston and cylinder unit (9, 9a) containing a hydraulic fluid, to the ram (12, 12a) of a distance-dependent mechanical press (6, 6a), characterised in that the cylinder chamber (19, 19a) of the piston and cylinder unit (9, 9a) is connected in fluid conductive manner to the forming chamber (20, 20a) of the forming tool (2, 2a).
3. A device according to claim 1 or 2, wherein the piston (10, 10a) of the piston and cylinder unit (9, 9a) is releasably fixed on the ram (12, 12a) via a piston plate (11, 11a) and the cylinder (8, 8a) is releasably fixed on the top die (4, 4a) via a cylinder plate (7, 7a), the piston plate (11, 11a) comprising return means, (13, 13a) which are fixedly associated therewith and which are connected relatively movably to the cylinder plate (7, 7a).
4. A device according to any one of claims 1 to 3, wherein a fluid separator (24) is incorporated in a conduit (23) between the piston and cylinder unit (9a) and the forming tool (2a).
5. A device according to any one of claims 1 to 4, wherein a pressure reducer (33) followed by a pressure limiting valve (37) is connected to a conduit (23, 27, 28) between the piston and cylinder unit (9a) and the forming tool (2a).

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