EP1363752A1

EP1363752A1 - Forming tool for hydromechanically deep-drawing workpieces from sheet metal blanks

Info

Publication number: EP1363752A1
Application number: EP02719899A
Authority: EP
Inventors: Christian Donhauser; Wolfgang Rauh; Mathias Mangliers; Ali Kaya; Matthias Golle
Original assignee: Audi AG
Current assignee: Audi AG
Priority date: 2001-03-02
Filing date: 2002-02-22
Publication date: 2003-11-26
Anticipated expiration: 2022-02-22
Also published as: ES2268008T3; US7007531B2; WO2002070163A1; DE50208136D1; US20040074274A1; JP2004520938A; DE10110161A1; EP1363752B1

Abstract

The invention relates to a forming tool (1) for hydromechanically deep-drawing workpieces from sheet metal blanks (2), said tool comprising a water tank (3), which acts as a lower tool and can be filled with a liquid active medium (8), thus forming the drawing die. The tool is also provided with a drawing ring (10), which is located in the upper section of the water tank (3) and is sealed against a volume of the active medium lying below. The boundary of the ring aperture (11) of the drawing ring (10) forms a drawing edge for the workpiece (2). The forming tool also comprises a drawing punch (9), which can be displaced with the sheet metal blank (2) interposed, through the ring aperture (11) of the drawing ring (10) into the section containing the active medium (8), whereby the sheet metal blank is pressed onto the drawing punch (9) using a reaction pressure as the application pressure, by means of a targeted displacement of the active medium (8). According to the invention, a water tank insert (14), which can be filled with active medium (8) to leave free the remaining water tank volume, can be positioned in the water tank (3), whereby the ring section of the drawing ring (10) lies tightly on the upper edge of the lateral walls (15, 16, 19, 20) of the insert.

Description

description

Forming tool for HV-mechanical deep drawing of workpieces

sheet metal blanks

The invention relates to a forming tool for HV-mechanical deep drawing of workpieces from sheet metal blanks according to the preamble of claim 1.

A known, generic forming tool (magazine "BLECH" No. 9/1963, page 575, picture 7) essentially consists of a water box, a drawing ring and a drawing punch and an actuatable hold-down device.

The water box is designed with box side walls and a box bottom as a tool trough, which can be filled with a liquid active medium as the lower tool and thereby forms the drawing die. The drawing is plate-shaped and arranged in the upper area of the water tank. With its ring area, it can be sealed against an underlying active medium volume. The edge of the ring opening of the drawing ring forms a drawing edge for the workpiece.

The drawing punch can be moved by means of an adjustable plunger such that it can be displaced through the ring opening of the drawing ring into the region of the active medium with the interposition of the sheet metal blank. The actuatable hold-down is used to hold the edges of the inserted Sheet metal blank, the holding pressure being selected such that the sheet metal blank edges can slide when the sheet metal cutout is loaded by the drawing die.

Specifically, the drawing ring with its ring area lies close to the upper edge of the water tank side walls. In addition, the hold-down presses the edge area of the sheet metal blank against a seal embedded in the drawing ring and thus seals the system containing the active medium to the outside. During the drawing process, the drawing punch penetrates the active medium, usually a water-oil emulsion, with the interposition of the sheet metal blank, as a result of which this is displaced via an adjustable throttle. The reaction pressure resulting from the throttle position causes the sheet metal blank to be pressed against the drawing die, as a result of which the workpiece can be produced with the appropriate shape.

For a given size of the water box, different workpieces can be manufactured with the same forming tool by exchanging and using different drawing rings, each with different ring openings and adapted drawing punch sizes. The following problems can occur:

In the case of relatively large workpieces, the drawing ring rests with its ring area on the water box side walls in such a way that it projects beyond the water box side walls towards the center of the water box only with a small free projection. During the forming process and the build-up of pressure in the active medium, this exerts pressure from below on this free projection, which, however, is easy to control due to the small projection width and does not lead to any noticeable deformation of the drawing ring. The situation is different when a smaller workpiece is produced using a drawing ring with a relatively small ring opening, the same water box firmly integrated in the forming tool also being used here. The ring area of the Ziehrings protrudes here with a wide overhang from the supports on the water box side walls over the active medium to the center of the water box. Therefore, during the forming process, the pressure in the active medium exerts a considerable force in the vertical direction upwards on the drawing ring. This can lead to permanent deformations of the drawing ring and / or to elastic deformations of the drawing ring during the forming process in the manner of a "sigh of relief", as a result of which the manufacturing quality and the reproducibility during workpiece production can be influenced in an unfavorable and uncontrolled manner. Such a deformation could at best be caused by a higher stability of such a pull ring would be prevented, however this would have to increase the plate thickness of the pull ring in comparison to drawings with smaller ring openings, which would lead to unfavorably higher production costs and higher weights in connection with difficulties in the exchange of the pull ring, with furthermore unfavorable adjustments of the hold-down positions and Drawing stamp paths to different drawing ring thicknesses would be required.

In contrast, the object of the invention is to develop a generic forming tool such that when using drawing rings with relatively smaller ring openings than the water box surface, deformation of the ring area during the forming process is largely prevented.

This object is achieved with the features of claim 1.

According to claim 1, the forming tool comprises at least one water box insert which is adjustable in the tool-integrated water box and which can be filled with active medium while keeping the surrounding water box volume free. The ring used for the drawing ring lies tightly on the upper edge of the insert side walls, a circumferential seal preferably being attached to the upper edge of the insert walls. is brought.

This clearly shows that a free projection of a ring area of the currently used drawing ring with a small ring opening is reduced compared to the initially described support on the water tank side walls. Appropriately, several water box inserts of different surface sizes are available, which can be combined with different drawing rings in such a way that there is only a small free ring area protrusion for the respective combination and thus the pressure in the active medium during the forming process only causes a slight force effect in the direction of "breathing" of the drawing ring ,

The same forming tool can thus advantageously also be used for the production of relatively small workpieces, while maintaining the tool-integrated, relatively large water box, without the problem of a drawing-related deformation of the drawing ring in the manner of "breathing" with a reduction in the manufacturing quality. The proposed water box insert is also easy and inexpensive to manufacture and can be quickly and easily set in the water tank when changing a drawing ring.

In a preferred embodiment, the water box insert is tubular with insert side walls which can be placed tightly on the water box bottom via at least one circumferential lower wall edge seal. Connections for the active medium, which are attached to the bottom of the water box within the water box insert, can therefore continue to be used here in accordance with a use of the entire water box.

Alternatively, the water box insert can also be produced as an insert container with its own insert base, in which case connections for the active medium are to be provided on the insert container side. In a preferred embodiment according to claim 4, the insert side walls have the same height as the box side walls of the water box integrated in the forming tool. This means that all the pull rings that can be used are at the same height level in the forming tool, so that the tool settings can essentially be retained even when the pull ring is replaced in conjunction with the use of a water box insert.

According to claim 5, it is proposed that spacers to adjacent inner sides of the box walls of the water tank are attached to the outside of the insert side walls in such a way that the water box insert can be positively adjusted in the water tank. This advantageously keeps the water box insert used immovable and in the same position in the water box.

A universal sheet metal holder is formed on the forming tool, which can be adjusted from an open position to a holding position, the bearing surfaces being arranged approximately above the water box side walls, since when using the entire water box volume with a drawing ring of a large ring opening size, the edges of the sheet metal cutout to be held there. When replacing and using a drawing ring with a smaller ring opening in connection with a water box insert, the edges of a correspondingly smaller sheet metal blank to be held by the hold-down device can be seen further towards the center of the water box. Since the universal sheet metal holder with its actuator should also be used here, it is proposed with claim 6 that the hold-down device comprises, in addition to the universal sheet metal holder, an exchangeable sheet metal holding ring whose ring opening corresponds approximately to that of the respective drawing ring. The sheet metal ring is directly or indirectly detachably connected to the universal sheet metal holder. The travel range and the holding force of the universal sheet metal holder are thus extended further towards the center of the water tank in the relevant area of the water tank insert and redirected to the relatively small ring opening of the current drawing ring.

Here, too, an inelastic and / or elastic deformation of the sheet metal holding ring can occur due to the fact that the holding force of the universal sheet metal holder acts radially far outside on the sheet metal holding ring and the supporting force at the edge of the sheet metal blank rests radially further inside on the drawing ring. If such a problem occurs depending on the circumstances, claim 7 proposes to releasably connect the respective sheet metal holding ring to a stable pickup ring, the ring opening of the pickup ring being at least as large as that of the sheet metal holding ring. The stable pick-up ring is detachably connected to the universal sheet metal holder on its ring side areas. The forces occurring in the hold-down device are thus absorbed essentially in the stable sensor ring without deformation. The pick-up ring can be used as a further universal component to which different sheet metal holding rings can be detachably connected. Only when a drawing ring opening larger than the ring opening of the transducer ring is required, should this also be changed.

Overall, a generic forming tool with only a few exchanges of workpiece-specific tool components can thus be used universally for producing workpieces of different sizes with high manufacturing quality.

The invention is explained in more detail with reference to a drawing.

Show it:

1 shows a schematic representation of a forming tool according to the invention for hydromechanical deep drawing of workpieces from sheet metal blanks according to a first embodiment, 2 shows a schematic illustration of a forming tool according to the invention for hydromechanical deep drawing of workpieces from sheet metal blanks according to an alternative embodiment,

Fig. 3 is a schematic, perspective top view of a water box insert, and

4 shows a schematic representation of a partial area of a forming tool for hydromechanical deep drawing of workpieces from sheet metal blanks according to the prior art.

4 schematically and by way of example shows a lower tool 106 as part of a forming tool 100 according to the prior art. This lower tool 106 comprises a water box 102 with box side walls 103, 104 and a box bottom 105, the water box 102 containing a liquid active medium 107, e.g. B. a water-oil emulsion, is filled and thereby forms the drawing die. A pull ring 108 is designed here in the form of a plate and is arranged in the upper region of the water box 102. With its ring area, it is sealed against an active medium volume underneath. The edge of the ring opening of the drawing ring 108 forms a drawing edge for the workpiece 101. A drawing punch, not shown here, can be moved by means of an adjustable plunger, also not shown here, in such a way that, with the interposition of the workpiece 101, it passes through a ring opening 109 of the drawing ring 108 into the area of the active medium 107 can be shifted. During this drawing process, the drawing punch, with the interposition of the workpiece 101, penetrates into the active medium 107 as a sheet metal blank, as a result of which this is displaced via an adjustable throttle, not shown here. The reaction pressure resulting from the throttle position then causes the sheet metal blank to be pressed against the drawing die, as a result of which the workpiece can be produced with the appropriate shape. 4, the workpiece 101 is made relatively small, so that the ring opening 109 of the drawing ring 108 is also made relatively small. As can also be seen from FIG. 4, in such a case the drawing ring 108 projects with a wide protrusion 110 from the supports on the water box side walls 103, 104 over the active medium 107 to the center of the water box. During the forming process, the pressure in the active medium 107 represented by the arrows 111 exerts a considerable force in the vertical direction upwards on the drawing ring 108. This can lead to the drawing ring 108 breathing out during the shaping process, as a result of which the manufacturing quality and the reproducibility in the manufacture of the workpiece are adversely affected in an uncontrolled manner.

In order to eliminate this problem of breathing deeply, the present invention proposes a forming tool 1 with which the above problems can be avoided. As can be seen from FIG. 1, the forming tool 1 for the hydromechanical deep drawing of a workpiece 2 from a sheet metal blank comprises a water box 3 with box side walls 4, 5 and a box bottom 6, which can be filled as a lower tool 7 with a liquid active medium 8 and thereby Drawing die forms.

Furthermore, this forming tool 1 comprises a drawing die 9 which can be moved by means of an adjustable plunger (not shown here) and which, with the interposition of the sheet metal blank 2, can be displaced through an annular opening 11 of a drawing ring 10 into the region of the active medium 8.

Furthermore, an actuatable hold-down device 12 is provided for holding the edges of the sheet metal blank 2 to be formed with a holding pressure that allows a sliding possibility when the pulling die 9 is loaded.

As can further be seen from FIG. 1, a water box insert 14 is set in the water box 3, which can be filled with the active medium 8 while keeping the remaining water box volume free. 3 shows the water tank 3 with the water tank insert 14 in a schematic and perspective top view. It can be seen from this that the water box insert 14 is tubular. As can be seen in turn from FIG. 1, the water box insert side walls 15, 16 are placed on the water box floor 6 via a circumferential lower wall edge seal 17, which is only shown here very schematically. The height of the insert side walls 15, 16 corresponds to the height of the box side walls 4, 5.

As can be seen in particular from FIG. 3, there are spacers 21, 22, 23, 24 on the outside of the insert side walls 15, 16, 19, 20 of the water box insert 14 in each case from the adjacent inner sides of the box side walls 4, 5, 25, 26 so attached that the water box insert 14 can be positively adjusted in the water box 3.

As can be seen from FIG. 1, the drawing ring 10 lies tightly with its ring region on the upper edge of the insert side walls 15, 16, a seal being provided by an upper wall edge seal 27 which is formed all the way around, as shown in FIG 1 is shown only very schematically and by way of example. A comparison of FIG. 1 with FIG. 4 of the prior art shows that the free protrusion of a ring area in a drawing ring 10 with a small ring opening 11 is considerably reduced by the water box insert 14 according to the invention, so that the pressure in the active medium 8 when Forming process can only cause a small force effect in the direction of a "breathing" of the drawing ring 10.

As can also be seen from FIG. 1, the hold-down device 12 consists in each case of a universal sheet metal holder 28 and of an exchangeable sheet metal holding ring 30, the ring opening 31 of which corresponds approximately to that of the associated drawing ring 10 and the ring area of which directly connects to the uni Versal sheet holder 28 is releasably connected.

As is shown schematically in the illustration in FIG. 1 by the arrows 32, 33, an inelastic and / or elastic deformation of the sheet metal holding ring 30 can occur in a structure according to FIG. 1 in that the holding force of the universal sheet metal holder 28 engages radially far outside on the sheet metal holding ring 30 and the supporting force on the edge of the sheet metal blank 2 on the drawing ring 10 lies radially further inside. In order to avoid this problem, it is proposed according to a particularly preferred embodiment according to FIG. 2 that a stable pickup ring 35 is inserted between the universal sheet metal holders 28 and a sheet metal holding ring 34, the sheet metal holding ring 34 being detachably connected to the pickup ring 35. A ring opening 36 of the pick-up ring 35 is approximately as large as that of the sheet metal holding ring 34 and covers it, that is to say is arranged directly above the ring opening 11 of the drawing ring 10. The stable pickup ring 35 is detachably connected to the universal sheet metal holders 28 on its ring side regions. With such a structure, the forces occurring in the hold-down device 12, 13 are thus absorbed essentially in the stable pick-up ring 35 without deformation.

Claims

Expectations

Forming tool for hydromechanical deep drawing of workpieces from sheet metal blanks,

with a water box with box side walls and a box bottom as a tool trough, which can be filled as a lower tool with a liquid active medium and thereby forms the drawing die,

with a plate-shaped drawing ring, which is arranged in the upper area of the water tank and can be sealed with its ring area against an active medium volume underneath, the edge of the ring opening forming a drawing edge for the workpiece,

with a pulling die which can be moved by means of an adjustable plunger and which can be shifted through the ring opening of the drawing ring into the region of the active medium with the interposition of the sheet metal blank, the sheet metal blank being able to be acted upon by a reaction pressure as contact pressure on the pulling die by a targeted displacement of the active medium.

with an actuatable hold-down device for holding the edges of the sheet metal blank to be formed, with a holding pressure which allows a sliding possibility when loaded by the drawing die,

characterized, that a water box insert (14) can be set in the water box (3), which can be filled with active medium (8) while keeping the remaining water box volume free, and

that the drawing ring (10) with its ring area on the upper edge of the

Insert side walls (15, 16, 19, 20) lie tight.

2. Forming tool according to claim 1, characterized in that the water box insert (14) is tubular with insert side walls (15, 16, 19, 20) which has at least one peripheral lower

Wall edge seal (17) can be placed on the water tank floor (6).

3. Forming tool according to claim 1, characterized in that the water box insert is adjustable as an insert container with insert side walls and an insert base in the water box.

4. Forming tool according to one of claims 1 to 3, characterized in that the height of the insert side walls (15, 16, 19, 20) corresponds to the height of the box side walls (4, 5, 25, 26).

5. Forming tool according to one of claims 1 to 4, characterized in that on the outside of the insert side walls (15, 16, 19, 20) spacers (21, 22, 23, 24) to adjacent inner sides of box walls (4, 5, 25 , 26) are attached in such a way that the water box insert (14) can be positively and repeatably adjusted in the same position in the water box (3).

6. Forming tool according to one of claims 1 to 5, characterized in

that the hold-down device (12) consists of a universal sheet-metal holder (28) which is adjustably arranged approximately above the box side walls (4, 5), and

that the hold-down device (12) comprises an exchangeable sheet metal holding ring (30; 34), the ring opening (31; 36) of which corresponds approximately to that of the respective drawing ring (10) and which is directly or indirectly releasably connected to the universal sheet metal holder (28) with its ring area is.

7. Forming tool according to claim 6, characterized in that

that between the universal sheet metal holder (28) and the sheet metal holding ring

(34) a stable pickup ring (35) is inserted and the sheet metal holding ring (34) is detachably connected to the pickup ring (35), an annular opening (31) of the pickup ring (35) being at least as large as that of the sheet metal holding ring (34) and this covers, and

that the transducer ring (35) is detachably connected to the universal sheet metal holder (28) on its ring side regions.