METHOD FOR THE PRODUCTION OF SHEET METAL PARTS AND DEVICE THEREFOR

Abstract

The present disclosure provides a method and a device for producing sheet-metal parts with substantially reduced spring-back.

Claims

1-9. (canceled)

10. A method for producing a sheet-metal part, wherein the method comprises: preforming a sheet into a metal preform in a preforming tool, wherein the metal preform is configured as an open profile with an opening and in its longitudinal extent has at least one flangeless portion and, at least in regions, surplus sheet material; and final forming of the metal preform into a sheet-metal part in a calibration tool comprising at least one calibration punch and at least one calibration die, in which the surplus sheet material in the metal preform is compressed by a relative movement between the calibration punch and the calibration die; wherein the metal preform is laid in the calibration tool such that its opening points downward and is positioned on the calibration punch, and that during final forming, because of the relative movement, the edge of the metal preform present at least in the flangeless portion comes into contact with a punch shoulder of the calibration punch rests thereon and is pressure-loaded; wherein during the relative movement, the calibration die passes by the punch shoulder of the calibration punch, at least in the region of the flangeless portion of the metal preform, with a minimum possible gap corresponding to between >0% and 20% of the material thickness of the inserted sheet, before the final forming is completed.

11. The method as claimed in claim 10, wherein the metal preform is provided with a floor which, during preforming, is loaded with a surplus sheet material at least in the region of the flangeless portion, such that a floor region pre-curved in the direction of the opening is produced during the preforming, so that the metal preform is positioned on the calibration punch at least via the pre-curved floor region, at least in the region of the flangeless portion of the metal preform, such that the edge of the metal preform present at least in the flangeless portion is arranged above the punch shoulder.

12. The method as claimed in claim 10, wherein the metal preform is provided with a floor in which, locally or in portions, embossings pointing in the direction of the opening are produced during the preforming, so that the metal preform is positioned on the calibration punch at least via the embossings such that the edge of the metal preform present at least in the flangeless portion is arranged above the punch shoulder.

13. The method as claimed in claim 10, wherein the metal preform is provided with a floor, wherein during insertion of the metal preform in the calibration tool, at least a part region of the floor comes into contact with at least one adjustable insert which is arranged in the calibration punch and spaced from the calibration punch on insertion of the metal preform, and the metal preform is positioned on the insert at least via the part region of the floor, at least in the region of the flangeless portion of the metal preform, such that the edge of the metal preform present at least in the flangeless portion is arranged above the punch shoulder.

14. A device for producing a sheet metal part, with at least one preform tool for preforming a sheet into a metal preform, wherein the metal preform is configured as an open profile with an opening and in its longitudinal extent has at least one flangeless portion and, at least in regions, surplus sheet material; and with at least one calibration tool for final forming of the metal preform into a sheet-metal part, wherein the calibration tool comprises at least one calibration punch and at least one calibration die, wherein the surplus sheet material in the metal preform is compressed by the relative movement between the calibration punch and the calibration die; wherein the metal preform is positioned on the calibration punch with its opening at the bottom, wherein the calibration punch has at least one punch shoulder which is provided at least in the flangeless portion of the metal preform, such that by the relative movement, the edge of the metal preform present at least in the flangeless portion can be brought into contact with a punch shoulder of the calibration punch, can rest thereon and be pressure-loaded, wherein the calibration punch is arranged stationarily and the calibration die movably in the calibration tool.

15. The device as claimed in claim 14, wherein the calibration punch has at least one adjustable insert which is arranged in the calibration punch and can be spaced from the calibration punch.

16. The device as claimed in claim 14, wherein the calibration die is formed in multiple pieces and has at least one adjustable die cheek at least in the flangeless portion of the metal preform.

17. The device as claimed in claim 14, wherein the punch shoulder has a maximum extent of the material thickness of the inserted sheet plus >0 to 0.35 mm.

18. The device as claimed in claim 14, wherein the device is integrated in one of a pressing line, a transfer press and a follow-on press.

Description

[0028] The invention is explained in more detail below with reference to drawings. The same parts carry the same reference signs. The drawings show:

[0029] FIG. 1 a schematic, perspective illustration of the production of a metal preform,

[0030] FIGS. 2 to 5 a sequence of steps at different times in the production of a sheet metal part according to an embodiment of the method according to the invention, and a device according to the invention, in a schematic sectional illustration, and a part extract from the device in a schematic perspective illustration, and

[0031] FIG. 6 a schematic, perspective illustration of the sheet-metal part.

[0032] FIG. 1 shows in schematic, perspective illustration a production of a metal preform (2) from a sheet (1) in a preform tool (10), not shown in detail. The metal preform (2) may be produced in one or more steps by means of any combinable forming process. Reference sign (10) covers the preform tool, consisting of one or more tools which are suitable for creating a metal preform (2) from a sheet (1). The sheet (1) is for example unwound and cut as a defined blank or forming plate from a metal bundle/coil (not shown), and made available for further processing. Preferably, the sheet (1) is made of steel, preferably a high-strength steel, for example with a material thickness between 0.5 and 4 mm. Alternatively, aluminum materials or other metals may be used.

[0033] FIGS. 2 to 5 show in a schematic sectional illustrationand FIGS. 3 and 4 also, on the right-hand side, in a schematic perspective drawinga partial extract of a device in longitudinal extent, and a sequence for performance of a method according to the invention and a device according to the invention, which relates at least to the embodiment of the calibration tool (20). The method according to the invention for producing a sheet-metal part (3), see FIG. 6, thus comprises at least two steps. Firstly, the method comprises preforming a sheet (1) into a metal preform (2) having in cross-section a floor and two wings, each with a transition between floor and wings.

[0034] The metal preform (2) or sheet-metal part (3) may comprise in the longitudinal extent (L) for example at least one flanged portion, here on the left side of the profile open at the bottom, and at least one flangeless portion (2.1). With at least one portion, viewed in the longitudinal extent (L), having a flange, which for example may be arranged on one side or also on both sides in different portions, in the region of the flange there is a transition between the wing and the flange. The statements below relate to an example with a portion in cross-section, wherein both sides of the metal preform (2) and accordingly two sides of the sheet-metal part are flangeless in at least one portion. Evidently only one side need be flangeless and the other side may have a flange in cross-section, or be completely flange-free (not shown).

[0035] The metal preform (2) is produced such that surplus sheet material (4) is provided which is arranged, preferably evenly distributed, in the metal preform (2) in the floor, or in the floor and in the transition between the floor and the wings. Further surplus sheet material may be present, in particular locally, in the metal preform (2), e.g. a further material addition respectively close to the two metal preform ends, in the floor and in a floor region (2.2) pre-curved in the direction of the opening (0) of the metal preform (2), so that the metal preform (2) can be positioned on the calibration punch (21) at least via the pre-curved floor region (2.2), at least in the region of the flangeless portion (2.1) of the metal preform (2), such that the edge (2.11) of the metal preform (2) present at least in the flangeless portion (2.1) is arranged above the punch shoulder (21.1), see FIG. 2.

[0036] Alternatively or additionally, the metal preform (2) is provided with a floor in which, locally or in portions, embossings (2.3) are provided pointing in the direction of the opening (), see drawing on the right of the metal preform (2) in FIG. 1 during production of the preform, so that the metal preform (2) can be positioned on the calibration punch (21) at least via the embossings (2.3), see FIG. 3, such that the edge (2.11) of the metal preform (2) present at least in the flangeless portion (2.1) is arranged above the punch shoulder (21.1). The embossings (2.3) made in the floor may be distributed in the longitudinal extent (L) along the floor or be present only as local or partial embossings (2.3) on the two ends of the metal preform (2.3), viewed in the longitudinal extent (L). If a sheet-metal part is to be produced with a flange at least in portions, these embossings need not necessarily be made in the region of the flangeless portion (2.1) of the metal preform (2). The embossings (2.3) made serve not only as spacers but may also provide further surplus metal material, at least in portions, viewed locally or in part in the transverse extent of the metal preform (2).

[0037] Further alternatively or additionally, at least one adjustable insert (21.2) may be arranged in the calibration punch (21), see FIG. 4, which can be spaced from the calibration punch (21) so that at least a part region of the floor comes into contact with the insert (21.2) when the metal preform (2) is laid in the calibration tool (20), and the metal preform (2) is positioned on the insert (21.1) at least via the part region of the floor, at least in the region of the flangeless portion (2.1) of the metal preform (2), such that the edge (2.11) of the metal preform (2) present at least in the flangeless portion (2.1) is arranged above the punch shoulder (21.1).

[0038] The metal preform (2) is final-formed into a sheet-metal part (3) in a calibration tool (20) comprising at least one calibration punch (21) and at least one calibration die (22) in which, by relative movement between the calibration punch (21) and calibration die (22), the surplus sheet material (4) in the metal preform (2) is compressed, see FIG. 5, left illustration before final forming, right illustration in final forming. It has proved advantageous that during the final forming, because of the relative movement, the edge (2.11) of the metal preform (2) present at least in the flangeless portion (2.1) comes into contact with a punch shoulder (21.1) of the calibration punch (21), rests thereon and is pressure-loaded in order in particular to cause the desired, at least local compression of the metal preform during the further press stroke.

[0039] With the embodiment according to the invention, before final forming or before closure of the calibration tool (20), it can be ensured that the metal preform (2) can be positioned on the calibration punch securely against clamping, and flangeless portions (2.1) as well as optional flanged portions can be final-formed to precise dimensions. For final forming of the exemplary flanged portions (not shown in FIGS. 2 to 5), in particular slides (not shown) are provided in the calibration tool for blocking the flange edges of the metal preform, so that these portions too can undergo the compressive stress superposition similarly to the flangeless portions (2.1).

[0040] After the metal preform (2 has been laid in the calibration tool (20) such that the opening () of the metal preform (2) points downward and is positioned on the calibration punch (21), during the relative movement, the calibration die (22) passes by the punch shoulder (21.1) of the calibration punch (21) with a minimum possible gap, at least in the region of the flangeless portion (2.1) of the metal preform (2), before final forming is completed or the compressive stress superposition initiated. Before the start of the compression/calibration process, it is thus ensured that at least the die cheek (22.1) of the calibration die (22) has passed the punch shoulder (21.1) of the calibration punch (21), so that during compressive stress superposition, uncontrolled flow between the punch shoulder (21.1) and the edge (2.11)which could lead to seizingis prevented. The drawing does not show that the calibration die (22) may also be made in multiple parts, for example with at least one leading die cheek (22.1).

[0041] After completion of final forming, the calibration tool (20) is opened again and the precisely dimension sheet-metal part (3) can be removed. The opened calibration tool (20) is thus free again, to be reloaded with a new preform (2) for final forming.

[0042] Preferably, at least one of the three above-mentioned embodiments, comprising a metal preform (2) with pre-curved floor region (2.2), a metal preform with local or partial embossings (2.3) in the floor, and/or adjustable inserts (21.2) in the calibration punch (21), serves for positioning of the metal preform (2) on the calibration punch (21).

[0043] The invention is not restricted to the embodiment shown. Other forms of sheet-metal part are also possible and require correspondingly adapted tools, preform and calibration tools. In particular, the tools (10, 20) may be configured as interchangeable tools and be used in a production line, in particular in a pressing line, transfer press and/or follow-on press.