DE19902741A1 - Deep drawing press has distance elements to adjust distance between blank holder abutment and punch holder for high drawing cushion pressures - Google Patents

Abstract

The press has a deep drawing punch (6) with holder (5) and a part (4) with abutment section (23) to hold a blank. There are controllable distance elements (12,12',12'') to adjust a distance between holder and abutment section. When the elements are active, the distance is approx. the same as or larger than, the thickness of the blank. The abutment part is formed by a drawing die. At least one of the distance elements is a plunger moved parallel to the holder by a pneumatic/ hydraulic piston cylinder unit, or an electromagnetic piston.

Description

The invention relates to a device for deep drawing Thermoformed parts with the characteristics of the generic term of the An Proverb 1. The invention also relates to a method for deep drawing of deep drawn parts with the characteristics of The preamble of claim 10.

Such a device usually comprises a drawing die ze, which has a concave shape area and a concave ven forming area enclosing abutment area, so like a drawing punch that has a convex shape area points. Such a device also has a holder on which surrounds the convex shape of the drawing die and the one for holding a deep-drawn board with the Wi the storage area of the drawing die cooperates, the Holder from a die cushion against the abutment area par allel to the punch stroke is drivable to a Randbe rich of the board, the so-called "Ziehteilflansch", between between the holder and the abutment area. Egg ne such device forms a component, esp special tool, a deep-drawing press, with the help of which  from plate-shaped, essentially two-dimensional plates tinen three-dimensional molded parts become. Metal sheets are preferably used to Deep drawing sheet metal components.

In conventional deep-drawing presses, egg is used for the implementation thermoforming process, first a board between the Wi storage area of the deep-drawing die and the holder brings. Then the drawing die with the abutment richly adjusted against the holder, with the die cushion that drives the holder against the abutment area, so that the board is clamped on the drawn part flange. The power with which the drawn flange between holder and abutment area is held by the die cushion pressure, through which the holder is pre-selected against the abutment area is set. This die cushion pressure must be one on the one hand be chosen as low as possible in order to achieve large drawing depths at low material thinning without tears. Because with a relatively low die cushion pressure they stay tractive forces prevailing on the drawn part flange are relatively small because the drawn part flange then has an edge inlet, at which the drawn part flange flows virtually from the through the ge Hal formed against the abutment area is pulled out. On the other hand, the aforementioned However, the die cushion pressure should be chosen so large that the Drawn part flange no qualitatively disadvantageous folds that can. Such folds can also cause  that the holder against the biasing force of the die cushion is pushed away from the abutment area, whereby a Gap between the drawn flange and the abutment area or the holder. This gap can be due to a regularly provided elastic pillow Increase the counter bracket undefined, which improves quality were no longer adhered to for the deep-drawn part can.

Modern deep drawing presses have controllable die cushions, where the die cushion pressure depending on the adjustment stroke of the die or the relative stroke between Ma trize and stamp can be varied in stages. To this Way, the clamping force with which the pull partial flange held between holder and abutment area is, and thus the flow behavior of the edge inlet visibly a low material thinning even with large ones Drawing depths can be optimized.

From the magazine "BLECH ROHRE PROFILE" 41 (1994) 4, Sei ten 237 to 240, it is known in a deep drawing press the edges occurring during a deep-drawing process run as a control variable for regulating the die cushion pressure use. The one for a deep-drawn part with sufficient quality characteristic course of the edge run-in depending frequency of stroke adjustment of the punch is as Re stored in a control unit. A ver  equal to the measured actual values for the edge run-in with the Setpoints stored in the reference curve result in ent speaking control commands for the die cushion pressure as a control size.

The present invention addresses the problem a device of the type mentioned above design that also in the production of deep-drawn parts at large depths of drawing a tendency to wrinkle and Cracking is reduced.

According to the invention, this problem is solved by a device solved with the features of claim 1.

The invention is based on the general idea that a clamping force with which the drawn flange between the Wi the storage area and the holder is clamped by a adjustable distance by means of controllable distance elements to vary between the abutment area and the holder. In particular, the clamping effect of the die cushion pressure fully activated by activating the spacer elements be lifted. This measure can always be a relative high die cushion pressure can be chosen, which makes the holder even in the case of wrinkles not over the distance from the abutment area that can. Wrinkling therefore always remains on given size limited, namely to the set Ab  stood between the abutment area and the holder Lich the thickness of the drawn part flange.

If the spacer elements are deactivated, the holder can from the die cushion through the die cushion pressure Press the drawn flange against the abutment area, see above that the clamping force or holding force of the drawn flange between the abutment area and the holder in the usual manner Die cushion pressure depends. When distance elements are activated can the holder only up to the measure of the distance against the Abutment area are pressed. Firstly, if the Ab stood smaller than the thickness of the drawn part flange the clamping force with which the drawn flange between Wi the storage area and holder is held by the front turned off distance and from die cushion pressure. On the other hand, if the preset distance is equal to or larger than the thickness of the drawn part flange, the clamp is completely removed by force and the drawn flange can be relative unhindered by the distance between abutments the area and holder formed gap are pulled out, regardless of what is still on the holder Die cushion printing.

The control of the spacers, i. H. their activation or deactivation, depending on the stroke adjustment of the drawing die performed relative to the abutment part the distances and the sequences of stroke adjusters  lungs with activated or deactivated spacer elements are individually adapted to the respective deep-drawn part. There through the deep-drawn part production with regard to a low material thinning, reduced wrinkling and a reduced crack formation can be optimized.

According to a preferred embodiment of the The device can be approximately the same distance as or greater than the thickness of between the abutment area and the holder arranged board can be selected. At one of the like embodiment, there is little or no Holding force for the drawn flange between the abutment area and the holder so that this is essentially free from the by the distance between the abutment area and Holder formed gap is extendable. Wrinkling is only in due to the die cushion pressure applied to the holder possible within tolerable and controllable limits.

In a preferred embodiment of the invention Device can be at least one of the spacer elements adjustable stamp parallel to the holder, the outside of the drawn part flange in the abutment part or is arranged in the holder and at least when activated Di stamping elements on the holder or on the abutment area for the system ge comes. With this measure, the distance between Bracket and abutment area particularly simple and direct can be set.  

The problem underlying the invention is also solved by solved a method with the features of claim 10.

The method according to the invention is based on the general Thoughts to form a deep-drawn part at least two Stroke phases for the stroke adjustment of the punch relatively to provide for the abutment part, with one stroke phase the spacer elements are activated and in the other lifting phase are deactivated. During the lifting phase with deactivated Di Stamped elements become the drawn flange in the usual way held between the abutment area and the holder. In contrast, the drawn flange can be used during the Lift phase with activated spacers essentially unhindered from the distance set by the Abutment area and holder trained gap pulled out be. According to a development of the invention Any number of lifting phases with de activated spacer elements and lifting phases with activated Distance elements follow one another, their number and their length or stroke individually from the respective deep-drawn part depends.

It is particularly advantageous if one is the last lifting phase Stroke adjustment of the drawing die relative to the abutment part with deactivated distance elements up to the maximum stroke of the Drawing stamp takes place. In this way, wrinkles that  during the previous lifting phase with activated Distan Z elements may have formed through which tensile forces acting on the drawn flange in the molding area Chen the board smoothed and by the fully effective Clamping force smoothed or leveled in the drawn part flange.

Other important features and advantages of the invention Appear device and the inventive method itself from the dependent claims, from the drawings and from the associated description of the figures using the drawings.

It is understood that the above and the following standing features to be explained not only in the ever because specified combination, but also in other com binations or alone can be used without the To leave the scope of the present invention.

Preferred embodiments of the invention are in the Drawings are shown and are in the following Be spelling explained in more detail.

Each shows schematically

Tung Fig. 1 is a sectional view of a Vorrich according to the invention,

Fig. 2 is an enlarged view of a element marked in Fig. 1 with II with deactivated distance and

Fig. 3 is a view as in Fig. 2, but with activated spacer elements.

According to Fig. 1, a deep-drawing tool 3 is introduced between a press table 1 and a press ram 2 of a deep-drawing press, not shown in the rest, which essentially consists of a drawing die 4 , a holder 5 and egg NEM punch 6 . The drawing die 4 alone forms an abutment part for the holder 5 and is fastened to a head plate 7 , which in turn is attached to the press ram 2 . The drawing punch 6 is attached to a base plate 8 which is attached to the press table 1 and is driven with this in a stroke-adjustable manner against the drawing die 4 . The holder 5 is driven via pulling sleeves 9 by a die cushion 10 parallel to the stroke adjustment of the die 6 relative to the die 4 . Arranged between the base plate 8 and the holder 5 is a drive-on plate 11 , which comes into contact with the base plate 8 when a maximum stroke adjustment for the drawing punch 6 is reached.

According to a first embodiment ( FIG. 1, left half), a plurality of spacer elements 12 are placed in the holder 5 , but only one of which is shown as an example. The spacer 12 is formed as a stamp or piston, which is mounted in a cylinder 13 axially parallel to the punch 6 adjustable. The piston or the Di punch element 12 limits on one side a hydraulic space 14 which can be connected to a hydraulic high pressure source via a hydraulic connection 15 . By the hydraulic pressure in the hydraulic space 14 , the spacer 12 is driven.

In a second variant, the spacer elements 12 ', of which only one is shown here by way of example, are accommodated in the drawing die 4 ( FIG. 1, left half).

In a third variant ( Fig. 1, right half), the spacer elements 12 ", of which only one example is shown in FIG. 1, can be accommodated in the holder 5 , the spacer elements 12 " in this embodiment being formed by pistons or Bolts are formed, which are mounted in a cylindrical opening 16 axially and parallel to the punch 6 adjustable. On an axial end face facing away from the drawing die 4, the spacer element 12 "is equipped with an outwardly convex link 17 which comes into contact with an actuating lever 18. This actuating lever 18 is pivotably mounted on the holder 5 , with a pivot axis 19 of the actuating lever 18 lies in a plane perpendicular to the direction of adjustment of the punch 6. The actuating lever 18 is led out laterally from the holder 5 and is in turn driven by an actuating element 20 , which preferably engages the axially free end of the actuating lever 18. The actuating element 20 can accordingly a first alternative as a gas pressure spring or steel spring or, according to a second alternative, as a controllable pneumatic or hydraulic piston-cylinder unit, a stop 21 for the actuating lever 18 is formed on the holder 5 , against which the actuating lever 18 comes to rest when the for the Spacer 12 "provided maximum male axial adjustment in the direction of the drawing die 4 is reached.

The holder 5 serves to hold or clamp a blank (not shown in FIG. 1) to be deformed in the deep-drawing process (cf. position 26 in FIGS. 2 and 3), the holder 5 having an end face 22 facing the drawing die 4 with a the drawing die 4 designed , the holder 5 facing abutment region 23 cooperates. An outer edge of the board ( 26 ), the so-called "drawn part flange" (cf. position 27 in FIGS. 2 and 3), is clamped between the holder 5 or its end face 22 and the abutment area 23 of the drawn die 4 .

The spacer elements 12 , 12 ', 12 "are each arranged on the holder 5 or on the drawing die 4 in such a way that they face outside the drawn part flange ( 27 ) on the opposite abutment surface, namely on the abutment area 23 of the drawing die 4 or on the end face 22 of the holder 5 come to rest.

Is the upper die 6 has a convex shape portion 25, is stretched over the the circuit board 26 at a stroke adjustment between upper die 6 and the drawing die 4, wherein the board 26 here also pressed into a corresponding concave shape portion 24 of the draw die 4 or subjected tiefge.

The method according to the invention for deep-drawing a deep-drawn part can, for example, proceed as follows according to FIGS. 1 to 3:
At the beginning, the holder 5 is in a maximally raised position and the drawing punch 6 is in a lowered position relative to it. The deep-drawn, plate-shaped in the initial state, essentially two-dimensional board 26 , which consists for example of sheet metal, in particular sheet steel, can then be placed on the end face 22 of the holder 5 . Subsequently, the drawing die 4 is lowered by a corresponding stroke adjustment of the press ram 2 . The drawing die 4 is adjusted until the board 26 comes into contact with the abutment area 23 of the drawing die 4 . The drawing die 4 then presses over the board 26 on the holder 5 , which is driven via the drawing sleeve 9 by the drawing cash register 10 in the direction of the drawing die 4 . The spacer elements 12 are deactivated so that the full die cushion pressure is transferred via the holder 5 to the board 26 , whereby the drawing part flange 27 is clamped between the holder 5 and the abutment area 22 of the die 4 . The deactivated Di punching elements 12 can come to the plant according to FIG. 2 at the counter bearing area 23 of the deep-drawing die 4 , but where they do not transmit any significant forces.

Then, with the spacer elements 12 deactivated, a first deep-drawing phase with a first stroke adjustment of the drawing die 6 takes place , the press table 1 and the press ram 2 moving apart. The convex shape of area 25 of the drawing punch 26 pulls the clamped not between the holder 5 and abutment area 23 portion of the board 26 into the concave shape portion 24 of the draw die. 4 Since the spacer elements 12 are deactivated during this first deep-drawing phase, the die cushion pressure causes the clamping of the drawn part flange 27 between the abutment region 23 and the holder 5 . In this case, accordingly, Fig. 2 between the drawing die holder 4 and 5, or between Wi derlagerbereich 23 and end face 22 a distance a that corresponds substantially to a thickness d of the board 26 in the area of Ziehteilflansches 27th The device according to the invention works during this first deep-drawing phase like a conventional deep-drawing press or like a conventional deep-drawing tool. In particular, during this first deep-drawing phase of the drawing part flange 27, with increasing stroke position of the drawing die 6, it is gradually pulled out of the clamping between the abutment area 23 and the holder 5 , the board edge running into the mold, so that this process is also referred to as "edge run-in".

Before a second deep-drawing phase following the first deep-drawing phase, the spacer elements 12 are activated, so that, according to FIG. 3, the distance a between the end face 22 of the holder 5 and the abutment region 23 of the drawing die 4 increases, in such a way that the from Holder 5 on the drawing part flange 27 transferred die cushion pressure reduced, in particular canceled. Preferably, the distance a set by the spacer elements 12 is slightly larger than the thickness d of the deep-drawing flange 27 , so that a gap 28 with a gap width s can form between the deep-drawing flange 27 and the holder 5 or the drawing die 4 , which is shown in FIG. 3 is shown large for a better illustration of exaggerated For example, with a board thickness d of 1 mm, a distance a of 1.2 mm can be set by the spacer elements 12 , so that the gap width is only about 0.2 mm. While in the case of deactivated spacer elements 12, the distance a results automatically from the thickness d of the drawn part flange 27 , it is determined by fourth spacer elements 12 by this.

In the course of the second deep-drawing phase, the drawing partial flange 27 can be pulled out unhindered from the released clamping between the abutment region 23 and the end face 22 , which results in a favorable force profile with regard to material thinning and crack formation. Even if there is a fold formation in the area of the gap 28 when the spacer elements 12 are activated, the folds can reach the gap width s maxi times, because the holder 5 still has the full die cushion pressure, which is so large that the holder 5 through a wrinkle formation cannot be pushed away from the drawing die 4 .

The folds that may form are eliminated in the course of a third deep-drawing phase following the second deep-drawing phase, during which the distance elements 12 are deactivated again. Wrinkles located in the gap 28 are ironed or leveled by the gap width s reduced to zero, while folds in the shaped area of the plate 26 are smoothed out by the tensile forces occurring during the remaining stroke adjustment.

The activation or deactivation of the spacer elements 12 and 12 'takes place by correspondingly applying hydraulic pressure to the hydraulic chambers 14 and 14 '. The activation of the spacer 12 "is carried out by a corresponding actuation of the piston-cylinder unit or actuating element 20 , which causes the actuating lever 18 to be pivoted.

Through the executable with the device according to the invention re inventive method can the production of Thermoformed parts with a reduced material thinning and thus with regard to a reduced crack formation can be improved without the risk of wrinkles education is increased. These advantages can also do this be exploited that especially in the manufacture of Sheet metal parts can be used which are made from one Lower quality sheet.  

Reference list

1

Press table

2nd

Press ram

3rd

Deep drawing tool

4th

Drawing die

5

holder

6

Drawing stamp

7

Headstock

8th

Base plate

9

Pull quill

10th

Die cushion

11

Ramp

12th

Spacer

13

cylinder

14

hydraulic room

15

Hydraulic feed / hydraulic connection

16

cylindrical opening

17th

Backdrop

18th

Operating arm

19th

Swivel axis of

18th

20th

Actuator

21

attack

22

Face of

5

23

Abutment area of

4th

24th

concave shape area of

4th

25th

convex shape area of

6

26

circuit board

27

Drawn flange

28

gap
a distance
d board thickness
s gap width

Claims (12)

1. Device for deep-drawing deep-drawn parts with a drawing die ( 6 ) having a convex shape region ( 25 ), with a holder ( 5 ) which surrounds the convex shape area ( 25 ) of the drawing die ( 6 ), and with an abutment part (4) having an abutment portion (23) cooperating to hold a deep-drawn board (26) to the holder (5), wherein the holder (5) by a die cushion (10) parallel against the abutment portion (23) to a Stroke adjustment of the drawing die ( 6 ) can be driven relative to the abutment part ( 4 ) in order to clamp an edge region ( 27 ) of the board ( 26 ) (drawn part flange) between the holder ( 5 ) and the Wi derlagerbereich ( 23 ), characterized in that controllable Spacer elements ( 12 ; 12 '; 12 ") are provided, with which a distance (a) can be set between the abutment area ( 23 ) and the holder ( 5 ). 2. Device according to claim 1, characterized in that the distance (a) with activated spacer elements ( 12 ; 12 '; 12 ") is approximately the same as or greater than egg ne thickness (d) between the abutment region ( 23 ) and Holder ( 5 ) arranged circuit board ( 26 ). 3. Apparatus according to claim 1 or 2, characterized in that the abutment part is formed by a drawing die ( 4 ) having a concave molding area ( 24 ), the abutment area ( 23 ) of the drawing die ( 4 ) the concave molding area ( 24 ) borders. 4. Device according to one of claims 1 to 3, characterized in that at least one of the spacer elements ( 12 ; 12 '; 12 ") is designed as a par allel to the holder ( 5 ) adjustable stamp, which outside the Ziehteilflansches ( 27 ) in the abutment part ( 4 ) or in the holder ( 5 ) and at least in the case of activated spacer elements ( 12 ; 12 '; 12 ") on the holder ( 5 ) or on the abutment area ( 23 ) comes to rest. 5. The device according to claim 4, characterized, that the stamp by a piston of a pneumatic or hydraulic piston-cylinder unit or by a electromagnetically driven piston driven or ge forms is. 6. The device according to claim 4, characterized in that the stamp on a from the holder ( 5 ) or the Wi derlagerteil ( 4 ) projecting on the holder ( 5 ) or on the Wi derlagerteil ( 4 ) pivotally mounted actuating lever ( 18 ) can be driven , which in turn can be driven by an actuating element ( 20 ) driven by the die ( 6 ). 7. The device according to claim 6, characterized in that the actuating element ( 20 ) is a gas pressure spring or a steel spring or a controllable piston-cylinder unit, the piston engages the actuating lever ( 18 ). 8. Apparatus according to claim 6 or 7, characterized in that the actuating element ( 20 ) on a base plate ( 8 ) is brought on, on which the drawing die ( 6 ) is attached. 9. The device according to claim 2, characterized in that the distance (a) with activated spacer elements ( 12 ; 12 '; 12 ") is about 20% greater than the thickness (d) of the board ( 26 ). 10. A method for deep-drawing deep-drawn parts with a device according to one of claims 1 to 9, characterized by the following steps:

• 1. A: Inserting a deep-drawn board ( 26 ) between the holder ( 5 ) and the abutment area ( 23 ) of the abutment part ( 4 )
• 2. C: activation of the spacer elements ( 12 ; 12 '; 12 "),
• 3. D: stroke adjustment of the drawing die ( 6 ) relative to the abutment part ( 4 ) with activated spacer elements ( 12 ; 12 '; 12 "),
• 4. E: deactivating the spacer elements ( 12 ; 12 '; 12 "),
• 5. F: Stroke adjustment of the punch ( 6 ) relative to the abutment part ( 4 ) with deactivated spacer elements ( 12 ; 12 '; 12 ") up to the maximum stroke of the punch ( 6 ).

11. The method according to claim 10, characterized in that the following step is carried out between steps (A) and (C):

• 1. B: stroke adjustment of the drawing die ( 6 ) relative to the abutment part ( 4 ) with deactivated spacer elements ( 12 ; 12 '; 12 ").

12. The method according to claim 11, characterized, that steps (B, C, D, E) are carried out repeatedly.