EP2701862B1 - Method and device for producing flanged drawn parts with simultaneous trimming - Google Patents

Description

The invention relates to a method and an apparatus for producing flanged drawn parts from a flat and / or preformed metal board using a drawing die with at least one cutting edge, a blank holder and a drawing die, wherein the drawing die a frame portion, a flange portion and a support area for has the board, the board placed on the support area of the drawing die and formed by retracting the draw punch in the drawing die in the drawn part and simultaneously cut at the flange. In addition, the invention relates to a device for producing flanged drawn parts with a drawing punch, which has at least one cutting edge, at least one hold-down and a drawing die with a flange portion in which the flange is formed, a frame portion and bottom portion, in which Zargen- and bottom portion formed and a support area for the board before the drawing process.

From the prior art methods and apparatus for the production of flanged drawn parts are known with which from a flat board drawn parts by deep drawing and trimming can be made in a working stroke. So is from the Textbook "Cutting, Punching and Drawing Tools", Öhler and Kaiser, 8th edition (2001 ), the drawing die, which comprises the bottom area, frame area and flange area of the drawn part to be produced, To perform vertically displaceable in order to cut the finished drawn part on the flange after the drawing process, so that in the result, the desired, flange-related drawn part can be made in a working stroke of the drawing punch. A corresponding drawing die is shown on page 429 in the cited textbook. Due to the height-adjustable drawing die, however, the structure of the known from the prior art cutting-tensile tool is relatively complex. Furthermore, there are already in the prior art methods and corresponding devices for the production of drawn parts with integrated trimming, which perform to avoid scraping the flange on the cutting edge of the drawing die the cutting process in a stretch-drawing step of the board, so that during the cutting process, the material under heavy tensile load stands and the flange area runs after the cut accordingly. Due to the relatively uncontrolled trailing of the flange so drawn parts can not be made dimensionally accurate with high process reliability. Finally, another problem is that the flange area must additionally extend obliquely to the frame area in order to avoid scraping on the sharp cutting edge. An often desired right-angled course of the flange area to the frame area can not be produced in one method step.

Deep-drawing presses do not have a high-precision tool guide, so that trimming operations in such presses are not possible or can only be carried out very difficult and expensive.

From the US 6,038,910 A and the SU 1 003 970 A1 Further tools for deep drawing of boards are known, which can also perform a trim.

In the WO 2008/025387 A1 discloses a method and a tool for hot working a circuit board, wherein cutting elements are provided in the dies of the tool. With the cutting elements, a trimming of the workpiece can be carried out simultaneously with the drawing process.

The DE 10 2006 026 805 A1 discloses an apparatus and method for hot working a semi-finished product having a die, a punch and a blank holder. A cutting device is provided on the punch and die, which cuts the semi-finished during forming.

In the DE 10 2010 000 608 B3 a device for pulling components from a board will be described. The board is trimmed during forming with an inlet contour and a cutting edge.

The present invention has therefore set itself the task of providing a method and an apparatus for producing flanged drawn parts with process-integrated trimming, which or a simpler construction of the tool, a self-centering system and at the same time a process-reliable, dimensionally accurate production of allows flange-drawn parts.

According to a first teaching of the present invention, the object of a method is achieved in that the Bearing area increased relative to the flange and fixed, wherein the height difference corresponds to at least the wall thickness of the formed sheet, during the retraction of the drawing die in the drawing die the cutting punch provided on the cutting edge with a provided at the transition between support area and flange area rounding, so that over the flange area projecting areas of the board are separated during the further drawing process.

In contrast to the method known from the prior art, according to the invention, the support area is raised in relation to the flange area and formed in a fixed manner, so that the tool as a whole can be of considerably simplified construction. Because the height difference between the support area and the flange area of the die corresponds at least to the thickness of the board, a perfect cutting process with the cutting edge of the drawing punch or the drawing die can be ensured. In addition, the fact that the at least one provided on the drawing punch Cutting edge engages with the provided between the support portion and flange portion rounding before completion of the drawing process, allows, in contrast to the conventional method, the flange portion is cut before the completion of the drawing operation. The method thus allows a particularly simple design of the tool, which manages without height-shifting areas and offers high flexibility of the arrangement of the flange. In addition, the infeed of the board during the drawing process can be controlled or adjusted via the height difference between the support area and the flange area as well as over the flange area width.

At the same time the interaction between the cutting edge on the punch and the opposite rounding on drawing die not only positively influence the cutting result, but due to the Selbstzentrierungseffektes achieved the advantage that the tool can be used in conventional deep-drawing presses, which usually no exact and accurate punch guide and thereby the structure of the tool can be kept simple.

According to a first embodiment of the method, the material flow during the drawing process and trimming is easily controllable in that the hold-down presses the region of the board to be severed during the drawing process and trimming the region of the board to be cut off onto the support region of the drawing die. In particular, the tensile load of the board during trimming thereby adjusted and thus influence the Cutting quality are taken. When using a wide hold-down device and a wide support surface of the drawing die, the semifinished product can in particular be clamped and stretched wrinkle-free.

According to a next embodiment of the method, the rounding along the cutting line has a varying engagement height with the cutting edge of the drawing punch, wherein the board is continuously cut during the retraction of the draw punch into the drawing die, starting from the areas of the curves which are first engaged with the cutting edge of the drawing punch becomes. In contrast to the method known from the prior art, in which the cutting of the blank after the end of the drawing operation is carried out simultaneously over the entire length of the cut line, the cutting forces and the cutting stroke can be reduced significantly. Namely, the engagement height varying along the cutting line with the cutting edge of the drawing punch of the rounding ensures that the cutting edge of the drawing punch comes into engagement with the round at different timings of the drawing punch, so that the trimming of the board respectively first into the first engaged Begins areas of rounding and then propagates continuously towards the other areas. The cutting line formed by the rounding with the cutting edge can then have, for example, a wavy course or an inclined course.

Preferably, the rounding has a radius of at least 0.5 mm. To the precision of trimming the board During the drawing process, it is advantageous to use a cutting edge with a maximum radius of 0.5 mm.

The same applies to a next embodiment of the method according to the invention, in which a cutting gap of 0.05 mm to a maximum of 0.2 mm between rounding and cutting edge of the drawing die is maintained.

Due to the interaction of the cutting edge (sharp edge) with the rounding, the tool is self-centering and thus positively influences the cutting quality.

The dimensional accuracy of the manufactured, flanged drawn parts can be further improved in a further embodiment of the method according to the invention that the board is pulled into a preform before pulling in the drawing die in a Vorziehgesenk and the preformed board provides a surplus of material, so that upon reaching the end position of the Drawing die the finished shaped and trimmed board is calibrated. The excess material can preferably be provided in the bottom region and / or in the drawing radius. As a result, by these two operations, namely preforming and final forming and trimming, a high-gauge, flanged drawn part can be provided by simple means.

Finally, the process can be further improved by hot-working the board in the drawing die. Of course, this is also optional for the preforming process. During hot forming, the blanks are heated to austenitizing temperature, thermoformed and rapidly cooled so that the drawn part is press hardened. In hot forming generally, on the one hand, lower forming forces result, on the other hand, a structure which is advantageous for the forming and which permits large degrees of deformation. In particular, the hot forming is used in blanks made of higher-strength or ultrahigh-strength steels, for example of the 22MnB5 type.

Alternatively, it is also possible, according to a further embodiment of the method according to the invention, to leave material along the cutting line, preferably in the form of webs, in other words. to produce an interrupted cutting line, whereby the drawn part is at least partially still connected to the trim area and at the same time can be removed from the tool (scrap removal via webs). In a further separation process, the cut area can be separated from the good part.

According to a further embodiment of the method according to the invention, a slit semifinished product can be used which has at least one slot, preferably at least two slits in the trimming area, which extends from an edge of the semi-finished product to the cutting line, whereby the trimming area is divided into several individual parts during the trimming (Scrap division) and thus the bad part can be removed more easily from the tool, for example by means of scrap chutes.

According to a second teaching of the present invention, the object is achieved by a device in that the support area is increased and fixed with respect to the flange area, wherein the height difference between the support area and the flange portion of the drawing die corresponds at least to the wall thickness of the board to be formed, between Supporting portion and the flange portion is provided a rounding, which is in engagement with a cutting punch provided on the cutting edge and allows trimming of the board during the drawing process. The device according to the invention does not require a height-adjustable drawing die, so that the costs for the production of the train can be significantly reduced. Moreover, the difference in height between the support area of the board and the flange area allows the flange of the drawn part to be formed very precisely into the flange area after it has been trimmed. In addition, the device allows a greater flexibility with respect to the orientation of the flange portion relative to the frame portion is achieved. The cost-effective tool with its simple design reduces wear and thus the cost of producing precise, flanged drawing parts.

If the height difference between the support area and the flange area of the drawing die corresponds to at least the wall thickness of the board to be reshaped, the indentation of the flange area of the drawn part can be controlled or adjusted via the height difference or over the flange width. A larger height difference between support area and flange area allows more material to be provided here and the flange area to have less feed. Of course, a minimum indentation must be ensured so that the drawn drawn part can still be removed from the tool.

In order to improve the quality of cut when engaging the rounding with the cutting edge and to achieve an improved self-centering of the system on the drawing die / drawing die, it is advantageous if the rounding has an inlet radius of at least 0.5 mm.

According to a further embodiment of the device according to the invention, the precision of trimming the flange of the drawn part is improved in that the cutting edge of the drawing punch has a maximum radius of 0.5 mm.

The same applies to a next embodiment of the device according to the invention, according to which a cutting gap between the cutting edge and the rounding of 0.05 mm to a maximum of 0.2 mm is provided.

In order to reduce the cutting forces but also the cutting impact during the drawing process, according to a further embodiment of the device according to the invention, the rounding along the cutting line on a varying engagement height with the cutting edge, so that the cutting edge at the beginning of the cutting process only point or area with the rounding engaged.

As already stated for the method, for example, the rounding, which varies in its engagement height with the cutting edge, permits a continuous trimming along the cutting line by retracting the drawing punch into the drawing die. As a result, the cutting forces and the cutting impact during the drawing process are significantly reduced.

Finally, the device according to the invention can be further improved in that the support area is connected to the drawing die in a highly precise manner, for example via a pinning, or is formed integrally with the drawing die. If the support area is formed integrally with the drawing die, the drawing die can be produced particularly inexpensively. On the other hand, there are significant advantages in the pinning of the support area with the drawing die in terms of maintenance. In this case, it is possible to replace the support area and possibly rework the rounding or cutting edge of the drawing die in a simple manner.

Fig. 1

in einer schematischen Schnittansicht eine Hälfte eines ersten Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung bei noch nicht abgeschlossenem Ziehvorgang,

Fig. 2

das Ausführungsbeispiel aus Fig. 1 bei Erreichen der Endposition des Ziehstempels,

Fig. 3

in einer schematischen Schnittansicht eine Hälfte eines Ausführungsbeispiels einer Vorrichtung zur Erzeugung einer Vorform in Endposition des Vorziehstempels,

Fig. 4

in einer schematischen Schnittansicht eine Hälfte eine Vorrichtung bei Verwendung der vorgeformten Platine aus Fig. 3,

Fig. 5

die Vorrichtung aus Fig. 4 bei Erreichen der Endposition des Ziehstempels,

Fig. 6

in einer schematischen Schnittansicht den Verlauf der Rundung des Auflagebereichs gemäß einem zweiten Ausführungsbeispiel und

Fig. 7

in einer schematischen Schnittansicht ein drittes Ausführungsbeispiel einer Einlaufkontur mit variierender Form.

The invention will now be explained in more detail with reference to embodiments in conjunction with the drawings. In the drawing shows

Fig. 1

1 is a schematic sectional view of a half of a first embodiment of a device according to the invention with the drawing process not yet completed,

Fig. 2

the embodiment Fig. 1 upon reaching the end position of the drawing punch,

Fig. 3

in a schematic sectional view of a half of an embodiment of an apparatus for producing a preform in the final position of the Vorziehstempels,

Fig. 4

in a schematic sectional view of a half of a device using the preformed board Fig. 3 .

Fig. 5

the device off Fig. 4 upon reaching the end position of the drawing punch,

Fig. 6

in a schematic sectional view of the course of the rounding of the support area according to a second embodiment and

Fig. 7

in a schematic sectional view of a third embodiment of an inlet contour with varying shape.

First shows Fig. 1 a first embodiment of a device according to the invention for the production of flanged drawing parts with a drawing punch 1, a drawing die 2 with a flange 3, in which the flange is formed, a frame portion 4 and a bottom portion 5, in which the Zargen- or bottom portions of the drawn part formed be and a support area 6 for supporting the board before the drawing process. In addition, the Device on a hold-7 and a rounding 8 between support area 6 and the flange portion 3. The rounding has an inlet radius of at least 0.5 mm, so that the material from the support area 6 can flow unhindered into the flange area. The support area 6 is raised relative to the flange area 3 and formed fixed. h indicates the height difference between the supporting area for the drawing board of the drawing die 6 and the flange area 3 of the drawing die. In the embodiment shown, h is slightly larger than the board thickness. The directional arrows each indicate the direction of movement of the blank holder 7 and the drawing punch 1.

The drawing punch 1 also has a cutting edge 9, which preferably has a radius of 0.05 mm. As in Fig. 1 As shown, in the drawing process, the blank 10 is pulled into the drawing die until the cutting edge 9 engages the rounding 8. Preferably, the hold-down is shut down at the beginning of the drawing process, so that it presses the board 10 against the support area 6 of the board. By this measure, the flow of material can be additionally controlled during the drawing process.

Moves the drawing punch 1, as in Fig. 2 shown, in the end position, the circuit board is cut due to the engagement of the cutting edge 9 of the drawing punch 1 with the rounding 8 of the support portion 6, so that over the flange portion 3 protruding parts of the board 10 are separated from this. As in Fig. 1 and 2 can be seen, the drawing die 2 is particularly simple design and still allows deep drawing with simultaneous trimming of the board. The support area 6 is in the present embodiment formed integrally with the drawing die, which corresponds to a particularly simple embodiment. However, it is also conceivable to realize the support region 6 via an exchangeable insert which is connected in a highly precise manner, for example via a pinning, to the drawing die. In this case, the replacement and reworking of the rounding 8, which of course is subject to wear, succeeds in a particularly simple manner.

Fig. 3 now shows in a schematic sectional view of a half of a device 11 for producing a preformed circuit board 12, which provides, for example in the bottom area a surplus of material. The device 11 for producing a preformed circuit board also consists of a die 13 and a drawing punch 14 and a hold-down 15.

Will, as in 4 and 5 shown schematically, the so preformed board 12 inserted in a device, the preformed board 12 can not only be drawn to the final shape, but also circumcised and calibrated simultaneously. For this purpose, provided in the bottom region 5 of the drawing die excess material of the preformed board. The difference over in the Figures 1 and 2 shown device is that on the drawing die 2 between support area 6 and flange 3 a cutting edge 8 'and the drawing punch 1 a rounding 9' are provided.

As in Fig. 4 , shows that the engagement of the cutting edge with the inlet contour takes place before the completion of the drawing process.

Fig. 5 shows schematically a device in the final position of the drawing die with calibrated, preformed board 12. The insertion of the board in the flange area is minimal and thus the drawn part so very accurate.

In Fig. 6 the rounding 8 between support area 6 and flange area 3 is shown schematically along its section line 8b. The section line 8b of the rounding 8 has a wave-shaped course, so that the cutting edge 9 of the drawing punch at the beginning of the cutting process only point or partially with the rounding 8 engages and the board can be continuously cut by retracting the drawing punch in the drawing die. 8a, the target section contour of the rounding 8 is designated, which corresponds to the desired dimension of the board. The representation in Fig. 6 is not to scale. About a calibration, such as in 4 and 5 shown, the rounding can be easily corrected in one step.

Furthermore, other gradients of rounding are possible. For example, a sawtooth or a linear profile of the engagement height of the rounding can be used. This shows, for example Fig. 7 schematically. In Fig. 7 has on the left side of the rounding 8 a small inlet radius, for example, 1 mm. On the right side, however, the inlet radius is significantly larger, for example, 5 mm. Accordingly, the cutting edge initially engages the left side first and continues its cut to the right side by retracting the draw punch into the die.

The cutting gaps, which are provided between the cutting edge 9, 8 'and rounding 8, 9', are preferably 0.05 mm to a maximum of 0.2 mm in order to ensure a particularly precise trimming of the board. In addition, the cutting edge of the drawing punch preferably has a maximum radius of 0.5 mm, in order to also ensure a particularly precise cutting process. As a result, with the device according to the invention, it is possible to provide particularly precise flange-shaped drawn parts with low investment costs for the die.

Claims (13)

1. A method for producing drawn parts having flanges from a flat and/or pre-formed metal blank (10, 12) using a drawing punch (1) with at least one cutting edge (9), using a blank holder (7) and using a drawing die (2), the drawing die (2) having a wall region (4), a flange region (3) and a supporting region (6) for the blank (10), the blank (10) being placed onto the supporting region (6) of the drawing die (2) and formed into the drawn part by moving the drawing punch (1) into the drawing die and cut at the flange region (3),
   the supporting region (6) being raised and stationary relative to the flange region (3), wherein the height difference (h) between supporting region (6) and flange region (3) corresponds at least to the material thickness of the blank (10, 12) to be deformed,
   characterised in that
   while the drawing punch (1) is moved into the drawing die (2), the at least one cutting edge (9) provided on the drawing punch (1) engages with a rounded portion (8) provided at the transition between supporting region (6) and flange region (3), so that regions of the blank (10, 12) that extend beyond the flange region (3) are cut off during the rest of the drawing process.
2. The method according to Claim 1,
   characterised in that
   during the process of drawing and cutting the blank (10, 12), the blank holder (7) presses the region of the blank (10, 12) that is to be cut off onto the supporting region (6) of the drawing die (2).
3. The method according to Claim 1 or 2,
   characterised in that
   the rounded portion (8) has a varying height of engagement with the cutting edge (9) along the cut line and the blank (10, 12) is cut continuously starting from the regions of the rounded portion (8) that engage with the cutting edge (9) first while the drawing punch (1) is moved into the drawing die (2).
4. The method according to any one of Claims 1 to 3,
   characterised in that
   a cutting edge (9) with a maximum radius of 0.5 mm is used.
5. The method according to any one of Claims 1 to 4,
   characterised in that
   a cutting clearance of 0.05 mm to a maximum of 0.2 mm is maintained between rounded portion (8) and cutting edge (9).
6. The method according to any one of Claims 1 to 5,
   characterised in that
   the blank (10, 12) is drawn into a preform in a predrawing die (11) before being drawn in the drawing die (2), and the preformed blank (12) provides excess material, so that the fully formed and cut blank (12) is calibrated when the end position of the drawing punch (1) is reached.
7. The method according to any one of Claims 1 to 6,
   characterised in that
   the blank (10, 12) is hot-formed in the drawing die (2).
8. A device for producing drawn parts having flanges, having
   a drawing punch (1), which has at least one cutting edge (9), having at least one blank holder (7) and having a drawing die (2), which has a flange region (3), in which the flange is formed, a wall region (4) and a bottom region (5), in which the wall region and bottom region are formed, and a supporting region (6) for the blank (10, 12) before the drawing process,
   the supporting region (6) being raised and stationary relative to the flange region (3), wherein the height difference (h) between the supporting region (6) and the flange region (3) of the drawing die (2) corresponds at least to the wall thickness of the blank (10, 12) to be deformed,
   characterised in that
   a rounded portion (8) is provided between supporting region (6) and flange region (3), said rounded portion engaging with a cutting edge (9) provided on the drawing punch (1) and allowing the blank (10, 12) to be cut during the drawing process.
9. The device according to Claim 8,
   characterised in that
   the rounded portion (8) has a minimum entry radius of 0.5 mm.
10. The device according to Claim 8 or 9,
    characterised in that
    the cutting edge (9) has a maximum radius of 0.5 mm.
11. The device according to any one of Claims 8 to 10,
    characterised in that
    a cutting clearance of 0.05 mm to a maximum of 0.2 mm is provided between the cutting edge (9) and the rounded portion (8).
12. The device according to any one of Claims 8 to 10,
    characterised in that
    the rounded portion (8) has a varying height of engagement with the cutting edge (9) along the cutting line, so that the cutting edge (9) engages with the rounded portion (8) only at some points or in some regions at the start of the cutting process.
13. The device according to any one of Claims 8 to 10,
    characterised in that
    the supporting region (6) is connected to the drawing die (1) in a highly precise manner or is designed in one piece with the drawing die (2).

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