WO2008040495A1

WO2008040495A1 - Device for even stretch-forming of workpieces

Info

Publication number: WO2008040495A1
Application number: PCT/EP2007/008443
Authority: WO
Inventors: Dejan Vlahovic; Mathias Liewald
Original assignee: Universität Stuttgart
Priority date: 2006-10-05
Filing date: 2007-09-28
Publication date: 2008-04-10
Also published as: EP2107952A1; DE102006047484A1; EP2107952B1

Abstract

The invention relates to a device for the even stretch-forming of workpieces, having a tool upper part (3) and a tool lower part (4), which engages with the tool upper part, which can move with respect to each other. Both the tool upper part and the tool lower part each have at least two forming crimps (5, 7), spaced apart from each other on at least two sides, which engage in corresponding recesses (6, 8) of the tool upper part or the tool lower part.

Description

Device for the flat ironing of workpieces

The invention relates to a device for the flat ironing of workpieces, with a tool upper part and a tool upper part engaging with the tool lower part.

From the general state of the art, the so-called Cyril-Bath method is known, in which a workpiece is clamped in a clamping device having at least two clamping elements and, if appropriate, formed with a forming tool, for example a deep-drawing tool. However, this method can also be used exclusively for the flat stretch drawing of sheets. The method of flat stretch drawing is used in particular for relatively flat workpieces in order to achieve sufficient solidification thereof.

The disadvantage of this method and the device used for this purpose, however, is the high technical complexity that is required for the hydraulics and their control or regulation and the measurement of force and displacement. This results in very high investment and maintenance costs. In addition, the known devices for performing the Cyril-Bath process are very large and require a lot of space.

From DE 195 04 264 Al a method and an apparatus for edge clamping during the forming pulling of sheets are known. In order to prevent the contact surfaces of the clamping frame parts having to be exactly touched, they are formed by end faces of beads, so that only at the edge of the sheet metal the areas of the end faces of the beads are created. The beads thus serve in this device solely and solely for clamping the sheet, which is formed during clamping by a separate tool, in particular a deep-drawing tool. Without such an additional deep drawing tool, the device described there could therefore not be used.

DE 195 04 649 C1 describes a method and a drawing tool for stretch drawing of metal sheets. In this case, the drawing tool in the region of its outer periphery on a dipping into a trench of the counter tool web. By this combination of the web with the trench a desired flow of the material is to be achieved in certain phases of the deformation.

DE 24 50 624 A1 describes a device for pressing deep, thin-walled container bottoms with large diameters, which has a tool insert and an anvil. The tool insert and the counter-holder in turn have a multiple drawing bead, which, as in DE 195 04 264 Al, acts as a hold-down during deep drawing of the workpiece and must apply very high hold-down forces.

However, all of the known methods are not able to perform a flat stretch drawing of workpieces.

It is therefore an object of the present invention to provide a device for the flat stretch drawing of workpieces, which has a simple construction and a small size and is able to perform a flat ironing in an exact manner.

According to the invention, this object is achieved by the features mentioned in claim 1. The forming beads according to the invention of the upper tool part and the lower tool part ensure a simultaneous holding and pulling of the workpiece, so that even with a single-acting press in a train a flat ironing and optionally subsequently a forming of the workpiece can be performed without the need for additional tools are required , The Umformsicken invention thus serve not only for holding, but for the simultaneous induction of a tensile force in the workpiece, which is responsible for the flat ironing. During the penetration of the Umformsicken into the corresponding recesses, the workpiece moves within a closed geometry of the Umformsicken. The workpiece is thus drawn according to the invention in this Umformsickengeometrie, wherein the tensile force is influenced by the geometry of the tool formed by the upper tool part and the lower tool part. Clamping of the workpiece, as is the case with devices known from the prior art, does not take place with the device according to the invention.

Due to the fact that the tool movement is induced by the movement of the press or of the press ram, advantageously no additional drive and only one tool are required for performing the flat stretch drawing, which leads to an extremely low control effort. Furthermore, the tool can be made very simple and compact and is thus produced in a cost effective manner.

The stretching operation thus takes place in one stroke and, if further forming is necessary or desired, can be preceded by the deep-drawing stroke or combined with a deep-drawing stroke, so that the high process times present in the previous methods can be considerably reduced. Because the workpiece is dynamic - A -

is held and pulled, the material can slide back into the tool in a subsequent drawing process, so that tears can be avoided in the workpiece and a high quality is ensured.

Due to the simple structure, the investment costs are essentially limited to material and manufacturing costs, so that the device according to the invention can be realized considerably cheaper than known devices. In fact, savings of up to 90% can be achieved in terms of investment in tooling costs.

Due to the described simple design of the tool, this can be used without any changes for the hot forming and thus also heated for flat ironing certain materials.

Here, the principal advantages of the Streckziehens, namely an increase in the strength of the workpiece, obtained so that bulges prevented and, where appropriate, additional effects can be achieved.

Since the two tool halves, ie the upper tool part and the lower tool part, never touch, no Touchier effort, so no adaptation of the tool surfaces to each other required. For the same reason, the maintenance effort is essentially limited to the cleaning of the tool.

In a very advantageous development of the invention can be provided that the Umformsicken and located between the Umformsicken recesses are arranged on two opposite sides of the upper tool part and the lower tool part. Such a trained device has a very simple construction and can be used for the flat stretch drawing of workpieces in one direction.

Alternatively, it can be provided that the Umformsicken are arranged on a total of four sides of the upper tool part and the lower tool part, wherein in each case two of the four sides facing each other. By means of such a device can be a flat ironing stretch of the workpiece to achieve in two directions.

Alternatively, it may also be provided that the Ummorficken are arranged on three sides of the upper tool part and the lower tool part in triangular shape. Such an embodiment of the device can be used in triangular tools.

Another possibility is that the Umformsicken and located between the Umformsicken recesses are arranged in a circle on the upper tool part and the lower tool part.

In addition to these embodiments, arrangements of the Umformsicken on more than four sides of the upper tool part and the lower tool part are conceivable.

If the height of the Umformsicken 20 - 120 mm, so on the one hand, a sufficient penetration depth of the Umformsicken in the corresponding recesses and thus a correspondingly strong deformation of the workpiece to achieve a corresponding effect in the flat ironing guaranteed and it prevents the other that the Umformsicken due to too high a height of the same can bend. In order to achieve a different degree of deformation over the surface of the workpiece, it may further be provided that the height of the Umformsicken varies over the length thereof.

A variation of the tensile force induced in the workpiece can be achieved if the Umformsicken the tool upper part and / or the lower tool part are designed so that they engage at different times with the recesses of the lower tool part and / or the upper tool.

One way of realizing the penetration of the Umformsi- cken at different times may consist in that the height of the Umformsicken on each side of the upper die and / or the lower die part is different, the height difference between adjacent Umformsicken is 5 - 30 mm.

For example, the Umformsicken can be higher on the outside of the upper tool part and / or the lower tool part as on the inside, so that first the outer portion of the tool comes into contact with the workpiece.

Alternatively, however, the Umformsicken on the inside of the upper tool part and / or the lower tool part may be higher than on the outside.

Furthermore, it can be provided that the edges of the Umformsicken facing the workpiece are provided with radii having a size of 1 - 20 mm, in particular from 2 - 10mm. The design of the radii of the workpiece facing edges of the Umformsicken has proved to be crucial in terms of Training of the tensile force induced in the workpiece exposed because smaller radii induce a higher forming force in the workpiece.

In order to utilize this effect, provision can be made, for example, for the forming bead, which first engages with the corresponding recess, to have a smaller radius than the last forming bead engaging the corresponding recess. As a result, a very high stress is induced in the workpiece as soon as the first forming bead penetrates.

If, in addition to the flat ironing, a further deformation of the workpiece is required or desired, then a deep-drawing tool can be arranged in a gap between the forming beads.

In this context, it can further be provided that in at least one of the recesses a spring-loaded hold-down element is arranged. Such spring-loaded hold-down elements improve the wrapping of the workpiece and thus ensure an improved forming process.

Further advantageous embodiments and developments emerge from the remaining subclaims. Embodiments of the invention are shown in principle with reference to the drawings.

It shows:

Figure 1 is a highly schematic representation of the device according to the invention with a tool upper part, a lower tool part and in addition a deep-drawing tool. FIG. 2 shows a first embodiment of the forming beads according to the invention in a first state; FIG.

FIG. 3 shows the device from FIG. 2 in a second state; FIG.

FIG. 4 shows the device from FIG. 2 in a third state; FIG.

FIG. 5 shows a second embodiment of the embossing beads according to the invention in a first state; FIG.

FIG. 6 shows the device from FIG. 5 in a second state; FIG.

FIG. 7 shows the device from FIG. 5 in a third state; FIG.

8 shows a section through one of the forming beads according to the invention;

9 is a perspective view of one of the Umformsicken;

10 is a plan view of the device according to the invention with a first configuration of the Umformsicken;

11 is a plan view of the device according to the invention with a second configuration of the Umformsicken;

FIG. 12 shows a plan view of the device according to the invention with a further configuration of the forming beads; FIG.

13 is a plan view of the device according to the invention with a further configuration of the Umformsicken. FIG. 14 shows a top view of the device according to the invention with a further configuration of the forming beads; FIG.

15 is a plan view of the device according to the invention with a further configuration of the Umformsicken;

16 is a plan view of the device according to the invention with a further configuration of the Umformsicken;

17 shows a plan view of the device according to the invention with a further configuration of the forming beads;

18 is a plan view of the device according to the invention with a further configuration of the Umformsicken;

FIG. 19 shows a top view of the device according to the invention with a further configuration of the forming beads; FIG.

FIG. 20 shows a plan view of the device according to the invention with a further configuration of the forming beads; FIG.

FIG. 21 shows a plan view of the device according to the invention with a further configuration of the forming beads; FIG.

FIG. 22 shows a further embodiment of the device according to the invention in a first operating state; FIG.

FIG. 23 shows the device from FIG. 22 in a second operating state; FIG.

FIG. 24 shows the device from FIG. 22 in a third operating state; FIG. FIG. 25 shows a further embodiment of the device according to the invention in a first operating state; FIG.

FIG. 26 shows the device from FIG. 25 in a second operating state; FIG. and

FIG. 27 shows the device from FIG. 25 in a third operating state. FIG.

1 shows a device 1 for the flat stretch-forming of a workpiece 2, represented by a dashed line, for example a steel, aluminum or titanium sheet. The device 1 has a tool upper part 3 and a tool lower part 4 engaging with the tool upper part 3. The upper tool part 3 and the lower tool part 4 are movable relative to each other, wherein in the present case, the lower tool part 4 is rigid and the upper tool part 3 can be moved by means of a drive device, not shown, but known per se. Optionally, the tool lower part 4 could be movable and the upper tool part 3 could be rigid or both tool parts 3 and 4 could be movable relative to one another. The upper tool part 3 and the lower tool part 4 are preferably made of a suitable tool steel, but for small series can also be used plastic materials. Ceramics or suitable composite materials can also be used for the upper tool part 3 and the lower tool part 4. For a hot forming can be provided to heat the upper tool part 3 and / or the lower tool part 4.

The upper tool part 3 has in each case on at least two sides thereof a plurality of Umformsicken 5, which in the relative movement between the upper tool part 3 and the lower tool part. 4 engage in corresponding recesses 6 of the lower tool part 4. Conversely, the lower tool part 4 has a plurality of Umforgesicken 7, which engage in respective recesses 8 of the upper tool part 3. In each case, the circumferential beads 5 and the recesses 8 of the upper tool part 3 and the Umformsicken 7 and the recesses 6 of the lower tool part 4 alternate. The Umformsicken 5 and 7 may be provided with a coating tion, for example, to influence the required forming forces.

In addition, in the embodiment of the device 1 shown in Fig. 1 in a space 9 between the upper die 3 and the lower tool part 4, a thermoforming tool 10 is arranged, which also consists of a tool upper part 11 and a lower tool part 12. The deep-drawing tool 10 may be formed in a manner known per se and, in particular, the deep-drawing tool 10 may also be dispensed with if the device 1 is used only for flat ironing of the workpiece 2 and no deep-drawing machining thereof is required. On the illustrated in Fig. 1, but not designated gas springs of the upper tool 11 can of course be omitted.

FIGS. 2, 3 and 4 show a first embodiment of the upper tool part 3 and of the lower tool part 4 and in particular of the outer mold beads 5 and 7 thereof. It can be seen that the upper tool part 3 has a total of four Umformsicken 5a, 5b, 5c and 5d and located therebetween recesses 8a, 8b and 8c. The lower tool part 4 has three Umformsicken 7a, 7b and 7c and located therebetween recesses 6a, βb and 6c. Here, between the innermost Umsummsicke 7c and one for placing the workpiece 2 serving Werkstückaufläge 2a also has a recess, namely the recess 6c, provided, in which engages the innermost Umformsicke 5d. The Umformsicken 7 of the lower tool part 4 should be at least as high as the workpiece support 2a. In the case where the deep-drawing tool 10 is present, the workpiece support 2a serves as a forming die or forms the same.

The forming beads 5a, 5b, 5c and 5d of the upper tool part 3 are interpreted in the illustrated embodiment so that they go at different times with the recesses 6a, 6b and 6c of the lower tool part 4 in engagement. In a manner not shown, the Umformsicken 7 of the lower tool part 4 could be designed accordingly. This applies in principle for all embodiments of the device 1 described below, in which reference is made to a particular embodiment of the Umformsicken 5 of the upper tool part 3. In the embodiment shown in Figures 2, 3 and 4, the Umformsicken 5a and 5b of the upper die upper part 3 are higher than the Umformsicken 5c and 5d on the inside. As a result, the two outer Umformsicken 5a and 5b in front of the two inner Umformsicken 5c and 5d engage the workpiece. 2

As can further be seen in FIGS. 2 to 4, the edges of the forming beads 5 and 7 facing the workpiece 2 are provided with radii whose size lies in particular in a range of 1 to 20 mm, in particular 2 to 10 mm. In order to induce a high tension in the workpiece 2 when the two first forming beads 5a and 5b penetrate into the workpiece 2, in the present case the forming bead 5a engaging first with the corresponding recess 6a has a smaller radius than the last with the corresponding recess 6c engaged forming bead 5d. The order of the differently sized radii of the Umformsicken 5 and 7 has a significant impact on the induced stress in the workpiece 2 and thus on the transformation of the same. The geometry of the Umformsicken 5 and 7 can be further adapted to the geometry and / or the material of the workpiece 2 to edit each workpiece 2 according to its requirements.

The movement of the workpiece 2 within the geometry of the Umformsicken 5 and 7 and its deformation can be observed in Figures 2-4. Here, a gap with a width between 2 - 5 mm between the Umformsicken 5 and 7 and the corresponding recesses 6 and 8 has been found to be very well suited for the movement of the workpiece 2, this value of course of the thickness of the workpiece. 2 depends.

In the present case, the two outer Umformsicken 5a and 5b together with the workpiece 2 engage. However, an embodiment is also conceivable in which the outermost forming bead 5a penetrates into the workpiece 2 as the first and in particular in front of the adjacent forming bead 5b.

The height of the Umformsicken 5 and 7 is in particular 20 - 120 mm and may be different on each side of the upper tool part 3 and / or the lower tool part 4. The height differences between adjacent Umformsicken 5a - 5d or 7a - 7c can be between 5 and 30 mm. In FIGS. 2 to 4, the tool upper part 3 has four forming beads 5 and the tool lower piece 4 has three forming beads 7. The minimum number of Umformsicken 5 or 7 is two, more than eight Umformsicken 5 and 7 are not required, each between two Umformsicken 5 a recess 8 and between two Umformsicken 7 is a recess 6. In Figures 5, 6 and 7, an embodiment of the device 1 is shown, in which the Umformsicken 5d and 5c on the inside of the upper tool upper part 3 are higher than on the outside thereof. As a result, the inner Umformsicken 5d and 5c come before the outer Umformsicken 5b and 5a with the corresponding recesses 6 of the lower tool part 4 into engagement. The information regarding the height of the Umformsicken 5 and 7 and attached to the same radii can essentially correspond to the information on the embodiment of Figures 2, 3 and 4, wherein the Umformsicken 5a - 5d of the upper tool part 3 have smaller radii than in the previous embodiment ,

As an alternative to the embodiments illustrated in FIGS. 2-4 or 5-7, it is also possible to design the forming beads 5 or 7 so that an intermediate forming bead 5 or 7 first enters the workpiece 2.

8 shows a cross section through any of the forming beads 5 or 7. It can be seen that the forming beads 5 and 7 have a substantially rectangular cross-section in the height direction, with the above-mentioned different radii being located on the side facing the workpiece 2 can. It has been found to be particularly suitable when the width of the Umformsicken is 10 - 40 mm.

In Fig. 9, an embodiment of one of the Umformsicken 5 or 7 is shown, in which the height varies over the length thereof. As a result, a different degree of deformation can be achieved over the surface of the workpiece 2, or certain areas can be shaped differently than other areas of the workpiece 2, as a result of which forming errors can optionally be avoided. FIGS. 10-21 show various embodiments of the arrangement of the forming beads 5 and / or 7 on the upper tool part 3 and / or the lower die part 4. In the present case, the upper die part 3 is shown with the forming beads 5, but the arrangement is of course also valid for the Forming beads 7 of the tool lower part 4.

In the embodiment of FIG. 10, the Umformsicken 5 and 7 and located between the Umformsicken 5 and 7 recesses 6 and 8 are arranged on two opposite sides of the upper tool part 3 and the lower tool part 4. The same applies to the embodiment of Fig. 11, in which the Umformsicken 5 and 7 and the recesses 6 and 8 on the longitudinal side instead, as in Fig. 10, on the broad side of the upper die 3 and the lower die part 4 are arranged. Similarly, the embodiments of Figures 12 - 15 are formed, in which case the Umformsicken 5 and 7 and the recesses 6 and 8 are bent in the longitudinal direction thereof.

In the embodiments of the device 1 according to Figures 16, 17, 18 and 19, the Umformsicken 5 and 7 and located between the Umformsicken 5 and 7 recesses 6 and 8 are arranged on four sides of the upper tool part 3 and the lower die part 4. In each case two of the four sides are opposite each other. Similar to the embodiments of FIGS. 10 to 15, here as well bent forming beads 5 and 7 and recesses 6 and 8 can be used along their length.

In the embodiment of the device 1 of Fig. 20, the Umformsicken 5 and 7 and the recesses 6 and 8 to three Pages of the tool shell 3 and the lower tool part 4 arranged so that they form a triangular shape. A similar closed shape of the Umformsicken 5 and 7 can also be seen in the embodiment of Fig. 21, in which the Umformsicken 5 and 7 and located therebetween recesses 6 and 8 are arranged in a circle on the upper die 3 and the lower tool part 4. Of course, completely different, in particular adapted to the shape of the workpiece 2 arrangements of the Umformsicken 5 and 7 and the recesses 6 and 8 are conceivable.

FIGS. 22, 23 and 24 show an embodiment of the device 1 in which respective shim plates 13 are arranged between the forming beads 5 and the upper die 3, by which the penetration depth of the Umformsicken 5 can be influenced in the workpiece 2, if different heights Shims 13 are used. Optionally, the shims 13 could also be provided on the lower tool part 4. Even without the shims 13, the Umformsicken 5 and 7 can be removably attached to the upper tool part 3 and the lower tool part 4.

Furthermore, according to FIGS. 22-24, the device 1 has a hold-down element 14 which is arranged between the upper die part 3 and the lower die part 2a and on the other hand, in particular by means of at least one gas spring, which is capable of wrapping around the work piece 2 to improve. In a manner not shown may be provided in one or more of the recesses 6 and / or 8 such hold-down elements.

In the case of the embodiment of the device 1 shown in FIGS. 25, 26 and 27, the deep-drawing tool 10 is again provided. seen, by means of which the workpiece 2 is not only just stretched during its processing, but also deep drawn after the flat ironing. In this connection, the forming die 5 closest to the deep-drawing tool 10 may be formed as a draw ring.

The embodiments described with reference to FIGS. 2-4 and those described with reference to FIGS. 5-7 can be combined with all the embodiments of FIGS. 10-21. In the embodiments according to FIGS. 17 and 18, it is particularly advantageous that the free cut corners between the individual forming beads 5 and 7 prevent the workpiece 2 from tilting between the tool upper part 3 and the tool lower part 4 and thus jamming the device 1.

Claims

claims

1. Device (1) for the flat stretch drawing of workpieces (2), with a tool upper part (3) and with the upper tool part (3) engaging lower tool part (4) which are movable relative to each other, wherein both the upper tool part (3) as well as the lower tool part (4) in each case on at least two sides in each case at least two mutually spaced Umformsicken (5,7), which engage in respective corresponding recesses (6,8) of the lower tool part (4) or the upper tool part (3).

2. Apparatus according to claim 1, since there is no return, that the forming beads (5, 7) and the recesses (6, 8) located between the forming beads (5, 7) are arranged on two opposite sides of the upper die piece (3 ) and the tool lower part (4) are arranged.

3. Device according to claim 1, characterized in that the forming beads (5, 7) and the recesses (6, 8) located between the forming beads (5, 7) are arranged on a total of four sides of the upper tool part (3) and the lower tool part (5). 4) are arranged, with two of the four sides facing each other.

4. Apparatus according to claim 1, since you characterized that the Umformsicken (5,7) and located between the Umformsi- (5,7) recesses (6,8) on three sides of the upper tool part (3) and the lower tool part (4) are arranged in triangular shape ,

5. Apparatus according to claim 1, since it rchgeke nn records that the Umformsicken (5,7) and located between the Umformsi- (5,7) recesses (6,8) circular on the upper die part (3) and the Tool lower part (4) are arranged.

6. Device according to one of claims 1-5, d a d u r c h e k e n e c i n e c e s that the height of the Umformsicken (5,7) is 20 - 120 mm.

7. Device according to one of claims 1-6, characterized in that the height of the Umformsicken (5,7) changes over the length thereof.

8. Device according to one of claims 1-7, characterized in that the Umformsicken (5,7) of the upper tool part (3) and / or the lower tool part (4) are designed so that they at different times with the recesses (6,8 ) of the lower tool part (4) and / or of the upper tool part (3) engage.

9. Apparatus according to claim 8, since you rchgekennzeichnet that the height of the Umformsicken (5,7) on each individual side of the upper tool part (3) and / or the lower tool part (4) is different, wherein the height difference between adjacent Umformsicken (5,7) is 5 - 30 mm.

10. Apparatus according to claim 8 or 9, characterized in that the Umformsicken (5,7) on the outer side of the upper tool part (3) and / or the lower tool part (4) are higher than on the inner side.

11. Device according to claim 8 or 9, characterized in that the Umformsicken (5,7) on the inside of the upper tool part (3) and / or the lower tool part (4) are higher than on the outer side.

12. Device according to one of claims 1 - 11, d a d u r c h e c e n e z e i c h e s that the Umformsicken (5,7) in the height direction have a substantially rectangular cross-section.

13. Device according to one of claims 1 - 12, characterized in that the workpiece (2) facing edges of the Umformsicken (5,7) are provided with radii having a size of 1 - 20 mm, in particular from 2 - 10mm ,

14. Device according to claims 8 and 13, characterized in that the first with the corresponding recess (6,8) engaging the forming bead (5,7) has a smaller radius has as the last with the corresponding recess (6,8) engaging the forming bead (5,7).

15. The device according to one of claims 1-14, wherein a width of the outer beads (5, 7) is 10-40 mm.

16. Device according to one of claims 1-15, characterized in that the Ümformsicken (5,7) are bent in the longitudinal direction.

17. Device according to one of claims 1 - 16, d a d u r c h e c e n e c e s in that there are arranged between the Ümformsicken (5,7) and the upper die (3) and / or the lower tool part (4) respective Unterlegplatten (13).

18. Device according to one of claims 1 - 17, d a d u r c h e k e n e c i n e in that the Ümformsicken (5,7) are provided with a coating.

19. Device according to one of claims 1-18, in that a deep-drawing tool (10) is arranged in an intermediate space (9) between the Ümformsicken (5,7).

20. The device according to claim 1, wherein a spring-loaded holding-down element is provided in at least one cutout (6, 8).

21. Device according to claim 19 or 20, characterized in that ie the forming tool (5, 7) closest to the thermoforming tool (10) is designed as a draw ring.