EP4026626A1 - Forming tool and method for operating a forming tool - Google Patents

Abstract

The invention relates to a forming tool for producing a shaped sheet metal part, with a stroke-adjustable upper tool part (1) and a lower tool part (3), of which the upper tool part (1) has a die (5) and the lower tool part (3) has a press table ( 7) with stamp (9). According to the invention, the upper tool part (1) has an adjustment unit (21) by means of which the die (5) in the upper tool part (1) can be stroke-adjusted between a lower press stroke position (P) and an upper idle stroke position (L ).

Description

The invention relates to a forming tool for producing a shaped sheet metal part according to the preamble of claim 1 and a method for operating a forming tool according to claim 9.

A generic forming tool for producing a shaped sheet metal part consists of a stroke-adjustable upper tool part and a lower tool part. The upper tool part has a die, while the lower tool part has a press table with a punch. For sheet metal forming, a sheet metal blank is placed in an open tool cavity of the forming tool, which is defined between the die and the punch. This is followed by a press stroke, in which the upper tool part is stroke-adjusted from top dead center over a closing path to bottom dead center. At bottom dead center, a press stroke stop of the upper tool part is in contact with a counter-contour on the lower tool part. In addition, at the bottom dead center, the die is spaced apart from the punch by a slight press stroke gap, specifically with the formed sheet metal part being interposed.

Before the start of series production of such shaped sheet metal parts, a start-up process takes place in the press system ( figure 8 ), in which the mutually facing forming surfaces of the die and the punch are finely machined in order to ensure perfect forming of the sheet metal part in series production. As part of the start-up process, the forming tool with idle stroke operated, i.e. with a press stroke carried out without a sheet metal blank. A collision ( figure 8 , reference character K) come into contact with the stamp forming surface, which can lead to damage to the die or the stamp.

From the DE 2016 002 765 B3 a device with a press and a tool protection system for processing sheet metal workpieces is known. From the EP 3 243 578 B1 a method and a press tool for producing a shaped sheet metal part are known. From the DE 10 2017 200 022 A1 a device for forming components is known. From the DE 10 2004 059 598 A1 a device for forming and hardening a metal sheet is known. From the DE 10 2004 006 126 A1 a press with a locked ram is known.

The object of the invention is to provide a forming tool for producing a shaped sheet metal part, the operation of which can be carried out with greater process reliability than in the prior art.

The object is solved by the features of claim 1 or claim 9. Preferred developments of the invention are disclosed in the dependent claims.

The invention is based on a forming tool whose stroke-adjustable upper tool part has a die, which can be stroke-adjusted during a press stroke from a top dead center via a closing angle to a bottom dead center, in which a press stroke stop of the upper tool part is in contact with a corresponding counter-contour on the lower part of the tool. According to the characterizing part of claim 1, the upper tool part also has an adjustment unit. With the aid of the adjusting unit, the die can be stroke-adjusted in relation to the press stroke stop of the upper tool part, specifically between a lower press stroke position and an upper idle stroke position. In sheet metal forming, the die is adjusted to its lower press stroke position, while in an idle stroke process, the die is adjusted to its upper idle stroke position, in which damage to the punch or die due to die deflection is avoided.

With a press stroke during sheet metal forming, the die is thus firmly adjusted to its lower press stroke position. When the bottom dead center is reached, the die, which is fixed in its press stroke position, is only a slight press stroke gap away from the punch, specifically with the formed sheet metal part being interposed. The press stroke gap is identical to the sheet thickness of the sheet metal part.

In contrast, in the case of an idle stroke, that is to say in the case of a press stroke carried out without a sheet metal blank, the die is adjusted to its upper idle stroke position. In this way, when the bottom dead center is reached, the die (in the upper idle stroke position) is spaced apart from the punch by an idle stroke gap which is dimensioned substantially larger than the press stroke gap. In this way, a collision of the die with the punch can be reliably avoided in idle stroke operation despite die deflection. For example, the idle stroke gap can be a few millimeters larger than the press stroke gap. This can be 0.5mm, for example, while the idle stroke gap can be 2mm, for example.

In a technical implementation, the die can be adjusted between the lower press stroke position and the upper idle stroke position via a vertical guide in the upper tool part. The vertical guide can have a support structure on which the die located in the press stroke position is supported with its component weight.

In the lower press stroke position, the die may be spaced one die stroke from the upper idle stroke position. In the press stroke mode, the die stroke path is blocked or not released by the adjustment unit. In contrast, in idle stroke operation (e.g. in a start-up process), the adjustment unit is to release the die stroke path up to the upper idle stroke position. In this case, the die can be adjusted from its lower press stroke position to its upper idle stroke position.

In a technical implementation, the lower tool part can have at least one sheet metal holder with an adjustable stroke. Its function is to press an inserted sheet metal blank against the die with a predefined sheet metal holding force during the press stroke. The die is thus adjusted in the press stroke over the closing path to bottom dead center, while at the same time the blank holder presses the inserted sheet metal blank against the die with the blank holding force.

In a preferred embodiment variant, the sheet metal holder can also be part of the adjustment unit with a dual function. In this case, during idle stroke operation, the blank holder can apply an actuating force to the die, by means of which the die is moved from its lower press stroke position to its upper idle stroke position. The adjustment takes place using the stroke path of the dies, which is released by the adjustment unit in idle stroke operation.

In a structurally simple embodiment variant, the adjustment unit can have an adjustment element for releasing and/or blocking the die stroke path. The adjustment element can be adjusted between a release position and a locked position. In the release position, the stroke of the die is released, while in the locked position, the stroke of the die is blocked. In a structurally simple variant, the adjustment element can be arranged so as to be adjustable transversely to the vertical direction of the tool. The setting element can preferably be arranged between a base of the upper tool part and the die. In this case, the adjustment element can be implemented in a space-saving manner as a flat profile, for example a plate, which has blocking sections that are thick in material and release sections that are thin in material. The locking portions and the releasing portions of the plate can be alternately registered with die projections. In the locked position, the platen locking portions are located between the upper die and the die bosses. On the other hand, in the release position, the plate release portions are located between the upper die and the die bosses.

An exemplary embodiment of the invention is described below with reference to the accompanying figures.

Fig. 1

in schematischer Darstellung ein Umformwerkzeug mit zugeordneter Pressensteuerung;

Fig. 2 bis 7

jeweils Ansichten entsprechend der Fig. 1 anhand derer unterschiedliche Prozessführungen des Umformwerkzeugs veranschaulicht sind;

Fig. 8

eine nicht von der Erfindung umfasste Vergleichsform in einer Ansicht entsprechend der Figur 7;

Fig. 9 und 10

Ansichten eines zweiten Ausführungsbeispiels.

Show it:

1

a schematic representation of a forming tool with associated press control;

Figures 2 to 7

each views according to the 1 on the basis of which different processes of the forming tool are illustrated;

8

a comparative form not covered by the invention in a view corresponding to FIG figure 7 ;

Figures 9 and 10

Views of a second embodiment.

In the 1 the structure and the mode of operation or control of a forming tool is described to the extent necessary for understanding the invention. Tool components that are not necessary for understanding the invention, such as ejectors, slides, or the like, have been omitted from the figures for reasons of clarity.

According to the 1 the forming tool has a stroke-adjustable upper tool part 1 and a lower tool part 3 . The upper tool part 1 is approximately box-shaped and carries a die 5, while the lower tool part 3 has a press table 7 with a punch 9 mounted thereon in a stationary manner. The die 5 and the stamp 9 limit one in the 1 open mold cavity 11. The lower mold part 3 also has two sheet metal holders 13 with an adjustable stroke, which carry a sheet metal blank 15 inserted into the open mold cavity 11.

The upper tool part 1 is mounted on a press ram 17, the stroke of which can be adjusted by means of a working cylinder 18 of a master cylinder arrangement, not shown. In the same way, the two sheet metal holders 13 can also be stroke-adjusted by means of an auxiliary cylinder arrangement (not shown). The forming tool is in the 1 associated with a press control 19, by means of which the main cylinder arrangement, the auxiliary cylinder arrangement and an adjustment unit 21 can be controlled.

In the 1 the adjustment unit 21 has a plate-shaped adjustment element 23 which is positioned between the die 5 and a bottom 31 of the upper tool part 1 . The plate-shaped setting element 23 can be moved between a release position F ( figure 5 ) and a blocking position S ( 4 ) adjustable. The plate-shaped setting element 23 is formed with blocking sections 25 of thick material and release sections 27 of thin material, which can be brought into alternating contact with matrix projections 29 depending on the setting movement s. The material-thin release sections 27 are implemented in the figures as recesses in the plate-shaped adjustment element 23 .

The plate-shaped adjustment element 23 is actuated via a drive 33 which is in signal communication with the press control 19 . The drive 33 can, for example, work mechanically/hydraulically or pneumatically.

A core of the invention is that the die 5 is not mounted in a stationary manner on the upper tool part 1, but rather via a vertical guide 35 between a lower press stroke position P ( 1 ) and an upper idle stroke position L ( 6 ) is adjustable.

The operation of the press system shown in the figures is based on the Figures 1 to 7 described: In the 1 the forming tool is shown with the tool cavity 11 open, with the upper tool part 1 being at top dead center OT. After the sheet metal blank 15 is positioned on the two sheet metal holders 13 in an insertion step, a press stroke H _P takes place, in which the upper tool part 1 moves from top dead center OT is stroke adjusted via a closing path to bottom dead center UT. At bottom dead center UT ( 3 ) is a press stroke stop 37 of the upper tool part 1 in contact with a corresponding counter-contour 39 on the lower tool part 3.

How from the 2 and 3 shows that the press stroke H _P is divided into two partial strokes H _P1 , H _P2 . In the first partial stroke H _P1 ( 2 ) the upper tool part 1 is brought into contact with the sheet metal blank 15 located on the two sheet metal holders 13 . The sheet metal holders 13 press the sheet metal blank 15 with a holding force F _H against the die 5. In the further course of the press stroke, H _P2 ( 3 ) the sheet metal blank 15 is pressed against the forming surface of the punch 9. At bottom dead center UT ( 3 ) the die 5 is spaced apart from the punch 9 by a slight press stroke gap h _P , with the formed sheet metal part being interposed.

After the shaped sheet metal part has been shaped, a return stroke (not shown) is carried out, in which the upper tool part 1 returns to its top dead center OT ( 1 ) is returned.

In the in the Figures 1 to 3 The process control shown is the die 5 with its component weight on a support structure 28 (ie retaining screws) of the vertical guide 35 is supported. The matrix projections 29 are brought into overlap with the material-thick blocking sections 25 of the plate-shaped insert element 23, so that a matrix lifting path Δm is blocked upwards. Accordingly, during the in the Figures 1 to 3 indicated press stroke H _P fixed the die 5 in its lower press stroke position P.

The following is based on the Figures 4 to 7 an idle stroke operation is described. In contrast to the press stroke Hp ( Figures 1 to 3 ) is not positioned between the die 5 and the punch 9 in the idle stroke H _L sheet metal blank 15. Accordingly, before the start of the idle stroke H _L in the figure 5 the plate-shaped setting element 23 is moved from its blocking position S to its release position F. In the release position F, the material-thin release sections 27 are brought into overlap with the matrix projections 29 . This way is a matrix stroke path Δm is released, via which the matrix 5 located in the press stroke position P up to the upper idle stroke position L ( 6 ) is stroke adjustable.

At the start of the idle stroke H _L , the upper tool part 1 is moved over a first idle partial stroke H _L1 ( figure 5 ) adjusted until the die 5 is brought into contact with the two blank holders 13. The second idle stroke partial stroke H _L2 ( 7 ), in which the upper tool part 1 is stroke-adjusted with its press stroke stop 37 to bottom dead center UT. At the same time, in the idle stroke partial stroke H _L2 , the two sheet metal holders 13 press with a stroke-adjustable actuating force Fs ( 6 and 7 ) the die 5 using up the released die stroke path Δm up to the idle stroke position L. Therefore, at the bottom dead center UT ( 7 ) of the idle stroke H _L the die 5 over an idle stroke gap h _L ( 7 ) spaced from the stamp 9, which is dimensioned significantly larger than the press stroke gap h _P ( 3 ).

In the figures 9 and 10 a second embodiment is shown, the structure and operation of which are identical to the embodiment of FIG Figures 1 to 7 is. Therefore, reference is made to the previous description. In contrast to the Figures 1 to 7 the adjusting unit 21 has a jaw control as a drive on both sides of the press. The jaw control is made up of a vertically adjustable drive jaw 45 and a horizontally adjustable adjusting jaw 47, which interact via inclined control surfaces 43. The adjusting jaw 47 is adjustably mounted in a horizontal carriage guide 47 .

With a vertical drive stroke of the two drive jaws 45, the respective associated adjusting jaws 47 are displaced in the horizontal direction, as a result of which the adjusting jaws 47 move the plate-shaped adjusting element 23 between the release position F ( 9 ) and the locked position S ( 10 ) move.

REFERENCE LIST:

1

upper tool part

3

lower tool part

5

die

7

press table

9

Rubber stamp

11

mold cavity

13

sheet metal holder

15

tin plate

17

press ram

18

working cylinder

19

press control

21

adjustment unit

23

plate-shaped adjustment element

25

restricted sections

27

release sections

28

supporting structure

29

die protrusions

31

floor

33

drive

35

vertical guidance

37

Press Stroke Stop

39

counter contour

41

vertically adjustable drive jaws

43

control surfaces

45

horizontally adjustable jaws

47

horizontal carriage guidance

Fs

power

FH

holding power

HB

press stroke

HP1, HP2

press partial strokes

HL

idle stroke

HL1, HL2

empty partial strokes

P

Press Stroke Position

L

idle stroke position

S

locked position

f

release position

s

actuating movement

hp

Press Stroke Gap

hs

idle stroke gap

Δm

die stroke

K

collision

Claims (9)

Forming tool for producing a shaped sheet metal part, with a stroke-adjustable upper tool part (1) and a lower tool part (3), of which the upper tool part (1) has a die (5) and the lower tool part (3) has a press table (7) with a stamp (9), wherein a sheet metal blank (15) can be inserted into an open tool cavity (11) for sheet metal forming, which is defined between the die (5) and the punch (9), and a press stroke (Hp) then takes place in which the upper tool part (1) can be stroke-adjusted from top dead center (TDC) over a closing path to bottom dead center (UT), in which a press stroke stop (37) of the upper tool part (1) is in contact with a counter-contour (39) on lower tool part (3), wherein at bottom dead center (UT) the die (5) is spaced apart from the punch (9) by a slight press stroke gap (h _P ), specifically with the formed sheet metal part being placed in between, characterized in that the upper tool part (1) has an adjustment unit (21), by means of which the die (5) in the upper tool part (1), in particular with respect to the press stroke stop (37), can be stroke adjusted, specifically between a lower press stroke position (P ) and an upper idle stroke position (L). Forming tool according to Claim 1, characterized in that in the press stroke (H _P ) the die (5) is adjusted to its lower press stroke position (P), and that the die (5) in its press stroke position (P) and in the lower Dead center (UT) is spaced apart by a slight press stroke gap (h _P ) from the punch (9), with the interposition of the shaped sheet metal part formed. Forming tool according to Claim 1 or 2, characterized in that in the case of an idle stroke (L), i.e. in the case of a press stroke carried out without a metal blank, the die (5) is adjusted to its upper idle stroke position (L), and that the die (5 ) in its upper idle stroke position (P) and at bottom dead center (UT) by an idle stroke gap (h _L ) is spaced from the ram (9) which is larger than the press stroke gap (h _P ). Forming tool according to one of the preceding claims, characterized in that the die (5) can be adjusted via a vertical guide (35) in the upper tool part (1) between the press stroke position (P) and the idle stroke position (L), and that in particular the vertical guide (35) has a support structure on which the die (5) located in the press stroke position (P) is supported. Forming tool according to one of the preceding claims, characterized in that in the lower press stroke position (P), the die (5) is spaced by a die stroke path (Δm) from the upper idle stroke position (L), and that when carrying out a press stroke (H _P ), the adjustment unit (21) blocks the die stroke (Δm), i.e. does not release it, and that the adjustment unit (21) releases the die stroke (Δm) especially when performing an idle stroke (L), so that the die (5) can be adjusted from its lower press stroke position (P) to its upper idle stroke position (L). Forming tool according to one of the preceding claims, characterized in that the lower tool part (3) has at least one sheet metal holder (13) with an adjustable stroke, which in the press stroke (H _P ) holds an inserted sheet metal blank (15) with a sheet metal holding force (F _H ) against the die ( 5) and that in particular the blank holder (13) is part of the adjustment unit (21) and that the blank holder (13) applies an actuating force (Fs) to the die (5) in order to carry out the idle stroke (L) in order to move the die (5) from its lower press stroke position (P) to its upper idle stroke position (L), in particular using up the die stroke path (Δm) released by the adjusting unit (21). Forming tool according to Claim 6, characterized in that the adjustment unit (21) for releasing and/or for blocking the die lifting path (Δm) has an adjusting element (23) which can be adjusted between a release position (F) and a blocking position (S), and that in the release position (F) the die lifting path (Δm) is released or in the blocking position (S), the die stroke path (Δm) is blocked, and that in particular the setting element (23) can be adjusted transversely to the vertical direction of the tool, and/or that the setting element (23) is between a base (31) of the upper tool part (1) and the die (5) is arranged. Forming tool according to Claim 9, characterized in that the adjusting element (23) has a plate with blocking sections (25) that are preferably thick in material and release sections (27) that are preferably thin in material, and in that the blocking sections (25) and the release sections (27) alternately overlap with dies - projections (29) can be brought so that in the blocking position (S) the blocking sections (25) are arranged between the upper tool part (1) and the die projections (29), and in the release position (F) the release sections (27) are arranged between the upper tool part (1) and the die projections (29). Method for operating a forming tool according to one of the preceding claims.

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