EP3243578A2 - Method and press tool for producing a complex sheet metal part with high draw depth - Google Patents

Abstract

Method for producing a complex sheet metal part by means of a press-bonded tool, comprising: - Inserting a sheet (M) and downward stroke of the upper tool part (120), wherein the sheet (M) in the edge region between the die ring (160) and hold-down (140) is clamped; - Further downstroke, wherein the sheet (M) is first pulled over extended punch inserts (131, 132, 133) and thereby local material supplies in the sheet (M) are generated; - Further down stroke to Matrizenring (160) and hold down (140) reach their dead points, while the punch inserts (131, 132, 133) are actively moved back and release the local material stocks and wherein the sheet (M) already partially between Matrizenring (160) and stamp (130) is formed; - Further downward stroke until the die (150) reaches its dead center, wherein the Nachfließen prevented from the edge region and the sheet (M) only by using the local material stocks between die (150) and punch (130) is fully formed. Furthermore, tool (100) suitable for carrying out this method.

Description

The invention relates to a method for producing a complex sheet metal part by forming a sheet metal by means of press-bound tool (press tool) and a press tool suitable for this purpose.

Complex sheet metal parts, in particular for use in body construction, differ from simple sheet metal parts (such as a cup or a tub) by a more complex design, typically different surface areas and especially other design features, for example. Design or styling edges and / or Stiffening edges with small radii, includes. Since the forming technology feasibility limits, the production of such complex sheet metal parts is sometimes extremely difficult and expensive. Particular problems exist when high draw depths are to be realized under series production conditions.

To realize high drawing depths are in the DE 10 2010 045 281 A1 a method and a device described in which by means of additional drawing stage in the form of a leading die insert, first a supply of material is generated. During the further drawing process, this material supply is released by pushing back the die insert and finally finished.

Based on this prior art, the present invention seeks to provide an improved method and an improved tool for producing a complex and in particular large-area (eg.> 0.5 m ^ 2) sheet metal part, with which Series production conditions with perfect part quality a high draw depth is achievable.

This object is achieved with a method according to the invention according to the patent claim 1 and by an inventive press tool according to the independent claim. Preferred developments and refinements of the invention are analogous to both subject matters of the dependent claims, the following description and the drawings.

• Einlegen eines Blechs, insbesondere in Gestalt einer Blechplatine, in das offene Werkzeug und Schließen des Werkzeugs durch Abwärtshub des Werkzeugoberteils, wobei das Blech in seinem Randbereich zwischen dem Matrizenring und dem Niederhalter geklemmt bzw. eingeklemmt wird;
• weiterer Abwärtshub bei dem der Matrizenring den Niederhalter nach unten verdrängt, wobei das Blech zuerst über die ausgefahrenen und über die Stempeloberfläche vorstehenden Stempeleinsätze gezogen wird und dabei im Blech lokale Materialbevorratungen erzeugt werden;
• weiterer Abwärtshub bis der Matrizenring und der Niederhalter ihre unteren Totpunkte erreichen, wobei gleichzeitig die Stempeleinsätze aktiv zurückbewegt werden und dadurch die zuvor erzeugten lokalen Materialbevorratungen freigeben und wobei das Blech bereits bereichsweise zwischen Matrizenring und Stempel ausgeformt wird;
• weiterer Abwärtshub, bis auch die Matrize schließlich ihren unteren Totpunkt erreicht, wobei durch eine doppelte randseitige Klemmung des Blechs zwischen dem Matrizenring und dem Niederhalter sowie zwischen dem Matrizenring und dem Stempel das Nachfließen von Blechmaterial aus dem Randbereich verhindert wird und das Blech lediglich unter Ausnutzung der zuvor erzeugten lokalen Materialbevorratungen zwischen der Matrize und dem Stempel fertig ausgeformt wird;
• gegebenenfalls Öffnen des Werkzeugs (durch Aufwärtshub des Werkzeugoberteils) und Entnehmen des Blechformteils.

The inventive method for producing a complex sheet metal part by means of press-bound tool (press tool), the lower part of the tool a punch, a surrounding the stamp (displaceable) low or plate holder and a plurality of movable punch inserts (with forming or shaping function) and the upper die has a die and a die ring surrounding the die has the following sequence:

• Inserting a sheet, in particular in the form of a sheet metal blank, in the open tool and closing the tool by downward stroke of the tool shell, wherein the sheet is clamped or clamped in its edge region between the die ring and the hold-down;
• another downward stroke in which the Matrizenring displaces the hold-down, the sheet is first pulled over the extended and over the stamp surface protruding punch inserts and are generated in the sheet local material stocks;
• further downward stroke until the die ring and the blank holder reach their bottom dead centers, at the same time the punch inserts are actively moved back and thereby release the previously generated local material stocks and wherein the sheet is already partially formed between the die ring and punch;
• further downward stroke, until the die finally reaches its bottom dead center, which is prevented by a double edge-side clamping of the sheet between the die ring and the hold-down and between the die ring and the punch the flow of sheet material from the edge region and the sheet only taking advantage of the previously generated local material stocks between the die and the punch is fully formed;
• if necessary, open the tool (by lifting the upper part of the tool) and remove the sheet metal part.

In the context of the kinematic reversal, a reverse arrangement of the upper tool part and lower tool part is possible with appropriate design of the tool parts.

The inventive method allows under production and press shop conditions, the production of a complex sheet metal part with high draw depth, especially with high Zargentiefe, and impeccable quality. In particular, a drawing depth is understood to mean a drawing depth (= drawing path in the working direction) of at least 200 mm, preferably at least 250 mm and in particular at least 300 mm. Within a closing or working stroke, the sheet metal part can be substantially finished, starting from a flat sheet-metal blank, so that no further forming operations, at least no forming operations that increase the drawing depth and / or substantially change the forming configuration, are required. In a press line thus the required drawing levels can be kept low or even reduced.

Active retraction of the stamp inserts is understood to mean that they are not passively displaced as is conventional in the art. be pushed back, but be actively moved back. This can be done, for example, by mechanical coupling of the respective punch inserts with the hold-down device, so that the punch inserts are moved back from the hold-down device or moved into or retracted into the stamp recesses provided for this purpose. This can be done synchronously or asynchronously (ie in a specific sequence and / or with different speeds), in order to thereby purposefully control the punch contact (= contact between sheet metal and punch surface or effective surface). The tool or press tool may also have stamp inserts, which are not actively, but passively pushed or pushed back in a conventional manner.

It is preferably provided that with at least one of the punch inserts in the sheet metal or sheet metal part, a design edge is generated with a small radius. The complex sheet-metal shaped part which can be produced by the method according to the invention can therefore also have at least one distinctive design edge, despite the considerable draw depth. Its outer edge radius is preferably only a few millimeters. This design edge is trailing edge-free, since the method according to the invention prevents the sheet from moving relative to the punch insert during the drawing process.

• ein erstes Werkzeugteil, insbesondere ein Werkzeugunterteil, das einen Stempel, einen den Stempel umgebenden verdrängbaren Niederhalter und mehrere bewegbare Stempeleinsätze, wenigstens jedoch einen bewegbaren Stempeleinsatz, aufweist, und
• ein zweites Werkzeugteil, insbesondere ein Werkzeugoberteil, das eine Matrize und einen die Matrize umgebenden Matrizenring aufweist.

The press tool according to the invention, which is in particular a deep-drawing tool, comprises

• a first tool part, in particular a lower tool part, which has a punch, a displaceable hold-down device surrounding the punch and a plurality of movable punch inserts, but at least one movable punch insert, and
• a second tool part, in particular a tool upper part, which has a die and a die ring surrounding the die.

The press tool according to the invention is further designed so that between the hold-down and at least one of the punch inserts, preferably all punch inserts, a mechanical coupling (ie, a coupling by means of mechanics), through which the relevant punch insert or the respective punch inserts during displacement and in particular during downward movement of the hold-down (ie, during the forming or pulling operation as described above) is actively moved back, d. H. is moved or retracted into the stamp recess / s provided for this purpose.

Preferably, the punch inserts are arranged in the press tool, so that in all critical areas at the start of drawing a material storage (as explained above) can be done.

Optionally, it may be provided that at least one of the punch inserts, in particular the punch insert coupled to the hold-down device, is additionally spring-mounted, for example by means of a gas pressure spring. Preferably, all punch inserts are additionally spring-mounted.

At least one of the punch inserts can be designed for a point contact (= small-area contact contact) with the sheet to be formed. At least one of the punch inserts may be formed for line contact with the sheet to be formed, in particular for forming a small radius design edge (as described above).

Also, the die may have at least one movable die insert, which is opposite to a punch insert, in particular for forming a design edge, and which is formed with a corresponding mating contour, so that the sheet between the punch insert and the Matrizeneinsatz embossed can be transformed. Such a Matrizeneinsatz is arranged analogously to a punch insert in a Matrizenausnehmung and preferably also resiliently mounted, for example. By gas spring.

Fig. 1

in schematischen Schnittdarstellungen ein erfindungsgemäßes Pressenwerkzeug und veranschaulicht in mehreren Einzeldarstellungen das damit ausführbare erfindungsgemäße Verfahren zur Herstellung eines komplexen Blechformteils.

The invention will be explained in more detail with reference to the drawing. The features shown in the drawing or explained below may be, even detached from concrete combinations of features, general features of the invention and further develop the invention. In the drawing shows the

Fig. 1

in schematic sectional views of a press tool according to the invention and illustrates in several individual representations the process of this invention for producing a complex sheet metal part.

The press tool 100 has a tool lower part 110 and a tool upper part 120. The press tool 100 is a deep-drawing tool, which is installed in a press, not shown, wherein the lower tool part 110 is arranged on the press table and the upper tool part 120 is fixed to the press ram. When lowering the press ram, the tool top 120 performs a downward stroke or stroke with a substantially continuous downward movement.

The lower tool part 110 has a punch 130, a lower or sheet holder 140 surrounding the punch 130 and displaceable downwards, and a plurality of movable punch inserts 131, 132 and 133. The punch inserts 131, 132 and 133 are in punch recesses arranged. The punch insert 131 is for line contact and the punch inserts 132 and 133 are formed for point contact. The upper tool part 120 has a die 150, a die ring or counterholder 160 surrounding the die 150, and a movable die insert 151. The tool 100 is designed for a drawing depth of at least 200 mm. The following describes the drawing process.

In the open tool 100, a sheet M in the form of a flat sheet metal blank (molding board) is inserted and the tool 100 is closed by moving down the press ram or the tool upper part 120. Here, the metal sheet M is clamped in its edge region between the opposite of the die 150 leading die ring 160 and the hold-140, as in Fig. 1 a shown. The punch inserts 131, 132 and 133 are in extended positions or starting positions in which they protrude beyond the stamp surface or surface.

Upon further downward stroke of the upper tool 120, the Matrizenring 160 displaces the hold-down 140 down. D. h., The hold-down 140 is moved together with the die ring 160 downwards and thereby moves relative to the stationary punch 130. (The hold-down 140 can in a conventional manner by a press or tool 100 belonging to the die cushion or supported by the same, as illustrated with the illustrated springs.) In this case, the sheet M is pulled over the extended punch inserts 131, 132 and 133, wherein in the sheet M local material inventories are generated. This is in Fig. 1b shown. The punch inserts 131, 132 and 133 are, for example, spring-mounted by means of gas springs, as with the springs shown illustrated, so that they press with a defined force against the sheet metal M. A small spring stroke, for example. 20 mm, is sufficient for this.

At the same time, by means of the middle punch insert 131 and the opposing die insert 151, a design edge with a small radius is formed in the sheet M, for which purpose the punch insert 131 and the die insert 151 are formed with corresponding forming sections. Also, the die insert 151 is, for example, spring-mounted by means of a gas spring, as illustrated by the symbolically illustrated spring.

Upon further downward stroke of the tool top 120, the die ring 160 and hold-down 140 are eventually moved to their bottom dead center, as in FIG Fig. 1c shown. At the same time, the punch inserts 131, 132 and 133 are actively, ie not moved back by displacement, whereupon the sheet M in the region of the punch inserts 131, 132 and 133 can successively create the punch surface or effective surface of the punch 130. In this way, therefore, a controlled stamp contact. Furthermore, the local material stocks are released for further forming. At the same time, the metal sheet M is already formed in a covering area between the die ring 160 and the punch 130, for which purpose the die ring 160 and the punch 130 are formed with corresponding effective surface portions.

The moving back or retraction of the punch inserts 131, 132 and 133 is effected by a mechanical positive coupling with the hold-down 140. For this purpose, the punch inserts 131, 132 and 133, for example, attached to a frame or a support plate 180, the or when moving down the hold-down 140 from a certain hold-down position (or from a defined Ziehwegposition) arranged by means of hold-down 140 Carrier 190 taken along or moved. For example, the frame 180 is resiliently supported on the base plate (not shown) associated with the tool base 110, as illustrated with the illustrated springs.

When the hold down 140 has reached its bottom dead center (see Fig. 1 c) are also the punch inserts 131, 132 and 133 in their retracted end positions. Depending on the objective, provision may be made for the punch insert end faces to lie behind the stamp surface (as in FIG Fig. 1c shown), finish flush with the stamp surface or still protrude over the stamp surface. The return movements and the end positions of the punch inserts 131, 132 and 133 are individually interpretable, so that asynchronous punch insert movements are possible. Notwithstanding the shown vertical directions of movement of the punch inserts 131, 132 and 133 and oblique directions of movement are possible, for example. By using slides.

As a result of further downward movement of the press ram or of the upper tool part 120, the trailing die 150 is now moved to its lower dead center, wherein the sheet metal M or the sheet metal shaped part is still finished in the middle region (in the outer region, the forming is already completed). That is, the die ring 160 first reaches its bottom dead center, then the die 150 continues to run to its bottom dead center, thereby forming the center region. Because of the marginal clamping of the sheet M between the Matrizenring 160 and the blank holder 140 and between the Matrizenring 160 and the punch 130 no or hardly sheet metal from outside to inside, ie to the center area, flow, so that the sheet M only by utilizing the previously by means of the punch inserts 131, 132 and 133 generated local material stocks between the die 150 and the Stamp 130 is formed embossed ready, with the spring-mounted die insert 151 recedes or displaced upwards. Alternatively, it may be provided that the middle punch insert 131 is not moved back and thus continues to press against the sheet metal M or against the die insert 151.

Fig. 1d shows the final state in which the hold-down 140, the die ring 160 and the die 150 are in their lower Bewegungsstotpunkten. The sheet or sheet metal workpiece M is fully formed. After opening the tool 100 by lifting or moving up the press ram or the tool upper part 120, the sheet metal part can be removed. Using the springs, the tool parts move into the in Fig. 1 a starting positions or positions shown back, so that the next sheet M can be inserted and transformed.

Claims (10)

Method for producing a complex shaped sheet metal part by means of a press-bound tool (100), whose lower tool part (110) has a punch (130), a hold-down (140) surrounding the punch (130) and a plurality of movable punch inserts (131, 132, 133) and the upper part of the tool (120) comprises a die (150) and a die ring (160) surrounding the die (150), with the following sequence: - Inserting a sheet (M) and closing the tool (100) by downward stroke of the tool upper part (120), wherein the sheet (M) in the edge region between the Matrizenring (160) and the hold-down (140) is clamped; - Further downward stroke in which the Matrizenring (160) the hold-down (140) displaced downwards, wherein the sheet (M) is first pulled over the extended punch inserts (131, 132, 133) and thereby local material supplies in the sheet (M) are produced ; - Further downward stroke until the die ring (160) and the hold-down (140) reach their bottom dead centers, at the same time the punch inserts (131, 132, 133) are actively moved back and release the previously generated local material stocks and wherein the sheet (M) already partially is formed between the die ring (160) and the punch (130); - Further downward stroke until the die (150) reaches its bottom dead center, wherein by a double edge-side clamping of the sheet (M) between the die ring (160) and the hold-down (140) and between the die ring (160) and the punch (130 ) prevents the flow from the edge area and the sheet (M) only by utilizing the local material stocks between the die (150) and the punch (130) is fully formed. Method according to claim 1,
characterized in that
the drawing depth is at least 200 mm, preferably at least 250 mm and in particular at least 300 mm. Method according to claim 1 or 2,
characterized in that
the punch inserts (131, 132, 133) are moved back by mechanical coupling with the blank holder (140). A method according to any one of the preceding claims;
characterized in that
the punch inserts (131, 132, 133) are moved back asynchronously. A method according to any one of the preceding claims;
characterized in that
with at least one of the punch inserts (131) a design edge with a small radius is generated. Press tool (100), in particular deep-drawing tool, for producing a complex sheet-metal shaped part, with - A first tool part (110) having a punch (130), a punch (130) surrounding the displaceable hold-down (140) and a plurality of movable punch inserts (131, 132, 133), and a second tool part (120) having a die (150) and a die ring (160) surrounding the die (150), characterized in that
a mechanical coupling exists between the hold-down device (140) and at least one of the punch inserts (131, 132, 133), by means of which the relevant punch insert (131, 132, 133) is actively moved back when the hold-down device (140) is displaced. Press tool (100) according to claim 6,
characterized in that
at least one of the punch inserts (131, 132, 133), in particular the punch insert (131, 132, 133) coupled to the hold-down device (140), is additionally spring-mounted. Press tool (100) according to claim 6 or 7,
characterized in that
at least one of the punch inserts (132, 133) is designed for point contact with the sheet (M) to be formed. Press tool (100) according to one of the preceding claims 6 to 8,
characterized in that
at least one of the punch inserts (131) is designed for line contact with the sheet (M) to be formed, in particular for forming a design edge with a small radius. A press tool (100) according to any one of the preceding claims 6 to 9,
characterized in that
the die (150) has at least one movable die insert (151) facing a punch insert (131), in particular for forming a design edge.

Images