EP1363752B1 - Forming tool for hydromechanically deep-drawing workpieces from sheet metal blanks - Google Patents

Description

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

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

The water tank is designed 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. The drawing ring is designed plate-shaped and arranged in the upper part of the water box. With its ring area, it can be sealed off from an underlying effective medium volume. The edge of the ring opening of the drawing ring forms a drawing edge for the workpiece.

The drawing punch is movable by means of an adjustable plunger such that it can be displaced through the annular opening of the drawing ring into the region of the active medium with the interposition of the sheet metal blank. The actuatable hold-down serves to hold the edges of the inserted Sheet metal blank, wherein the holding pressure is selected so that a Gleitmöglichkeit the Blechzuschnittränder consists in a load of the sheet metal section by the drawing punch.

Specifically, here lies the drawing ring with its ring area on the upper edge of the water tank side walls close to. In addition, the hold-down presses the edge region of the sheet metal blank against a seal embedded in the draw ring and thus seals the system containing the effective medium to the outside. During the drawing process, the drawing punch penetrates with the interposition of the sheet metal blank in the active medium, usually a water-oil emulsion, whereby it is displaced by an adjustable throttle. The resulting according to the throttle position reaction pressure causes a pressing of the sheet metal blank to the drawing punch, whereby the workpiece with a corresponding shape can be produced.

For a given size of the water box can be made by replacing and using different drawing rings, each with different ring openings and custom draw punch sizes with the same forming tool corresponding to different workpieces. The following problems may occur:

With relatively large workpieces, the drawing ring with its ring area lies on the water box side walls in such a way that it projects beyond the water box side walls to the center of the channel box only with a small free projection. During the forming process and the pressure build-up in the active medium this exerts a pressure from below on this free supernatant, which, however, is easy to control because of the small protrusion width and does not lead to any appreciable deformation of the pull ring. The situation is different in a production of a smaller workpiece using a drawing ring with a relatively small ring opening, wherein the same integrated water box is firmly used in the forming tool also here. The ring area of the Ziehrings protrudes here with a wide projection from the supports on the water box side walls above the active medium to the center of the water tank. During the forming process, therefore, the pressure in the active medium on the large overhang surface exerts a considerable force in the vertical direction upwards on the draw ring. This can lead both to permanent deformations of the drawing ring and / or to elastic deformations of the drawing ring during the shaping process in the manner of a "breathing", whereby the production quality and the reproducibility during workpiece production can be adversely and uncontrollably influenced. Such a deformation could at best be prevented by a higher stability of such a drawing ring, whereby, however, the plate thickness of the drawing ring would have to be increased in comparison to drawing rings with smaller ring openings. This would lead to unfavorably higher manufacturing costs and higher weights in conjunction with difficulties in Ziehringaustausch, with also unfavorable adjustments of Niederhalterstellungen and drawing punch paths would be required to different Ziehringstärken.

The object of the invention is in contrast to develop a generic forming tool so that when using draw rings with respect to the water box surface relatively smaller ring openings deformation of the annular area during the forming process is largely prevented.

This object is achieved with the features of claim 1.

In accordance with claim 1, the forming tool comprises at least one adjustable in the tool integrated water tank water tank insert, which is fillable with the active medium while keeping the surrounding water tank volume. The drawing ring used here lies with its annular area on the upper edge of the insert side walls tight, for which purpose preferably mounted a circumferential seal on the upper edge of the insert walls is.

This is obviously a free projection of a ring portion of the currently used Ziehrings reduced with small ring opening relative to the above-described edition of the water tank side walls. It is expedient to have a plurality of water box inserts of different surface sizes which can be combined with different draw rings such that only small free ring area projections exist for the respective combination and thus the pressure in the active medium during the forming process causes only a small force action in the direction of "drawing" the drawing ring.

Advantageously, therefore, the same forming tool while maintaining the tool-integrated, relatively large water box can also be used for the production of relatively small workpieces, without the problem of pressure-induced Ziehringverformung in the nature of a "breathing" with a reduction in manufacturing quality. The proposed water tank insert is also easy and inexpensive to produce and adjustable when changing a drawing ring quickly and easily in the water box.

The water box insert is formed in a preferred embodiment according to claim 2 tubular with insert side walls, which are tightly placed over at least one circumferential lower edge wall seal on the water tank bottom. Connections for the active medium, which are mounted within the water box insert at the bottom of the water box, thus can continue to be used here according to a use of the entire water box.

Alternatively, the water box insert according to claim 3 can also be produced as a use container with its own insert bottom, then use container side connections are provided for the active medium.

In a preferred embodiment according to claim 4, the insert sidewalls have the same height as the box sidewalls of the forming tool integrated channel box. Thus, all usable draw rings are at the same height level in the forming tool, so that essentially the tool settings can be maintained even with a draw ring exchange in connection with the use of a water box insert.

According to claim 5, it is proposed that spacers are attached to adjacent inner sides of box walls of the water box on the outside of the insert side walls in such a way that the water box insert is positively adjustable in the water box. As a result, the water tank insert used in each case is advantageously held immovably and in the same position in the water tank.

On forming tool a universal plate holder is formed, which is adjustable from an open position to a holding position, wherein the bearing surfaces are arranged approximately above the water box sidewalls, since when using the entire water tank volume with a drawing ring large ring opening size there are to be held edges of the sheet metal section. In an exchange and use of a drawing ring with a smaller ring opening in conjunction with a water tank insert are to be held by the hold-down edges of a correspondingly smaller sheet metal blank further towards the center of the water tank. Since the universal plate holder is to be used here with his actuator here, is proposed in claim 6, that the hold-down comprises in addition to the universal plate holder an exchangeable plate holding ring whose ring opening corresponds approximately to that of the respective drawing ring. The sheet metal retaining ring is detachably connected directly or indirectly with the universal sheet holder. Thus, the travel and the holding force of the universal plate holder continue to the center of the water tank in the relevant area of the water tank insert and the relatively small ring opening of the current drawing redirected.

Again, an inelastic and / or elastic deformation of the sheet metal holding ring occur in that the holding force of the universal sheet metal holder radially far outside attacks on the sheet holding ring and the supporting force at the edge of the sheet metal blank on the drawing ring rests radially further inside. If, depending on the circumstances such a problem occurs is proposed with claim 7, releasably connect the respective sheet holding ring with a stable pickup ring, wherein the ring opening of the pickup ring is at least as large as the sheet metal retaining rings. The stable pickup ring is detachably connected at its ring side areas with the universal plate holder. The forces occurring in the holddown are thus absorbed substantially in the stable pickup ring without deformation. The pickup ring can be used as another universal component to which different sheet metal retaining rings can be detachably connected. Only when a Ziehringöffnung larger than the ring opening of the pickup ring is needed, this is also to change.

Overall, therefore, a generic forming tool with little replacement of workpiece-specific tool components can be universally used to produce different sized workpieces with high production quality.

Reference to a drawing, the invention is explained in detail.

Fig. 1

eine schematische Darstellung eines erfindungsgemäßen Umformwerkzeugs zum hydromechanischen Tiefziehen von Werkstücken aus Blechzuschnitten gemäß einer ersten Ausführungsform,

Fig. 2

eine schematische Darstellung eines erfindungsgemäßen Umformwerkzeugs zum hydromechanischen Tiefzeihen von Werkstücken aus Blechzuschnitten gemäß einer alternativen Ausführungsform,

Fig. 3

eine schematische, perspektivische Draufsicht auf einen Wasserkasteneinsatz, und

Fig. 4

eine schematische Darstellung eines Teilbereichs eines Umformwerkzeugs zum hydromechanischen Tiefziehen von Werkstücken aus Blechzuschnitten gemäß dem Stand der Technik.

Show it:

Fig. 1

a schematic representation of a forming tool according to the invention for the hydromechanical deep drawing of workpieces from sheet metal blanks according to a first embodiment,

Fig. 2

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

Fig. 3

a schematic, perspective top view of a water box insert, and

Fig. 4

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

FIG. 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 includes a water box 102 with box side walls 103, 104 and a box bottom 105, wherein the water box 102 with a liquid active medium 107, z. As a water-oil emulsion, is filled and thereby forms the drawing die. A drawing ring 108 is here plate-shaped and arranged in the upper region of the water box 102. With its ring area it is sealed against an underlying medium volume. The edge of the ring opening of the drawing ring 108 forms a pulling edge for the workpiece 101. A drawing punch, not shown here, is movable by means of an adjustable plunger, likewise not shown here, in that way, with the interposition of the workpiece 101, through an annular opening 109 of the drawing ring 108 the active medium 107 can be displaced. In this drawing process, the drawing punch penetrates with the interposition of the workpiece 101 as a sheet metal blank in the active medium 107, whereby it is displaced via an adjustable throttle, not shown here. The resulting according to the throttle position reaction pressure then causes a pressing of the sheet metal blank to the drawing punch, whereby the workpiece can be made with appropriate shape. 4, the workpiece 101 is formed relatively small, so that the ring opening 109th of the drawing ring 108 is also relatively small. As can be further seen from FIG. 4, in such a case the drawing ring 108 protrudes with a broad projection 110 from the supports on the water box sidewalls 103, 104 over the active medium 107 toward the center of the water box. During the forming process, therefore, the pressure represented by the arrows 111 in the active medium 107 exerts on the large overhang surface 110 a considerable force in the vertical direction upwards on the pull ring 108. This can lead to an inhalation of the drawing ring 108 during the forming process, as a result of which the manufacturing quality and the reproducibility during the production of the workpiece are adversely and uncontrollably influenced.

In order to eliminate this problem of respiration, 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 hydromechanical deep drawing of a workpiece 2 from a sheet metal blank comprises a water tank 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 the Drawing die forms.

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

Further, an operable hold-down 12 is provided for holding the edges of the reshaped sheet metal blank 2 with a sliding possibility at a load by the drawing punch 9 permitting holding pressure.

As can be further seen in FIG. 1, a water box insert 14 is set in the water tank 3, which can be filled with the active medium 8 while keeping the remaining volume of water tank free.

In Fig. 3, the water tank 3 is shown with water box insert 14 in a schematic and perspective plan view. It can be seen that the water box insert 14 is tubular. 1, the water box insert side walls 15, 16 are placed on the water box bottom 6 via a peripheral bottom edge seal 17, which is only shown here extremely 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, spacers 21, 22, 23, 24 to the adjacent inner sides of the box side walls 4, 5, 25, 26 are on the outside of the insert side walls 15, 16, 19, 20 of the water box insert 14 attached that the water box insert 14 can be adjusted positively in the water tank 3.

As can be seen from FIG. 1, the drawing ring 10 lies with its annular area on the upper edge of the insert side walls 15, 16 tight, wherein a seal via an upper wall edge seal 27, which is formed circumferentially, as shown in FIG is shown only very schematically and by way of example takes place. A comparison of FIG. 1 with FIG. 4 of the prior art shows that the free supernatant of a ring area in a drawing ring 10 with a small annular opening 11 is considerably reduced by the inventive water box insert 14, so that thus the pressure in the active medium 8 at Forming process can cause only a small force in the direction of a "breathing" of the drawing ring 10.

As can be further seen from FIG. 1, the hold-down device 12 consists in each case of a universal plate holder 28 and of an exchangeable plate holding ring 30 whose annular opening 31 corresponds approximately to that of the associated drawing ring 10 and which with its ring area directly to the universal plate holder 28 is releasably connected.

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

Claims (7)

1. Forming tool (1) for hydromechanically deep-drawing workpieces (2) from sheet metal blanks, comprising a water box (3) having side walls (4, 5) and a base (6) as a tool trough which, as the lower tool (7), can be filled with a liquid active medium (8), thereby forming the female die; a plate-like drawing ring (10) which is arranged in the upper region of the water box (3) and is sealable by its annular region with respect to an active medium volume located below said annular region, the edge of the annular opening (11) forming a drawing edge for the workpiece (2); a male die (9) movable by means of a adjustable ram and displaceable through the annular opening (11) of the drawing ring (10) into the region of the active medium (8), the sheet metal blank being interposed, whereby the sheet metal blank can be pressed on to the male die (9) with a reaction pressure as the application force through a specified displacement of the active medium (8); and an actuatable blank holder (12) for retaining the edges of the sheet metal blank to be formed with a retaining pressure permitting a possibility of sliding when loaded by the male die (9), characterised in that a water box insert (14) can be placed in the water box (3) and can be filled with active medium (8) while the remaining volume of the water box remains free, and in that the annular region of the drawing ring (10) bears sealingly against the upper edges of the side walls (15, 16, 19, 20) of the insert (14).
2. Forming tool according to claim 1, characterised in that the water box insert (14) is in the form of a tube having side walls (15, 16, 19, 20) which can be placed in abutment with the base (6) of the water box via at least one continuous lower wall edge seal (17).
3. Forming tool according to claim 1, characterised in that the water box insert is can be placed in the water box as an inserted container having insert side walls and an insert base.
4. Forming tool according to any one of claims 1 to 3, characterised in that the height of the insert side walls (15, 16, 19, 20) corresponds to the height of the side walls (4, 5, 25, 26) of the box (3).
5. Forming tool according to any one of claims 1 to 4, characterised in that spacers (21, 22, 23, 24) for maintaining a distance from adjacent inner faces of box walls (4, 5, 25, 26) are so mounted on the outer faces of the insert side walls (15, 16, 19, 20) that the water box insert (14) can be placed form-fittingly and repeatably in the same position in the water box (3).
6. Forming tool according to any one of claims 1 to 5, characterised in that the blank holder (12) consists of a universal sheet metal holder (28) which is arranged adjustably approximately above the side walls (4, 5) of the box (3), and in that the blank holder (12) includes an exchangeable sheet metal holding ring (30; 34), the annular opening (31; 36) of which corresponds approximately to that of the respective drawing ring (10) and the annular portion of which is directly or indirectly connected detachably to the universal sheet metal holder (28).
7. Forming tool according to claim 6, characterised in that a rigid receiving ring (35) is positioned between the universal sheet metal holder (28) and the sheet metal holding ring (34), and the sheet metal holding ring (34) is connected detachably to the receiving ring (35), an annular opening (31) of the receiving ring (35) being at least as large as that of the sheet metal holding ring (34) and coinciding therewith, and in that the receiving ring (35) is connected detachably by its lateral portions to the universal sheet metal holder (28).

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