EP3525952B1 - Method for shaping a workpiece by internal high-pressure shaping - Google Patents

Description

A tool for internal high-pressure forming of workpieces is specified. Furthermore, a method for forming a workpiece by internal high-pressure forming is specified.

In internal high-pressure forming (IHU), for example, a metallic starting pipe part is formed into a pipe-like component or IHU component by applying high internal pressure. The starting pipe part is placed in the cavity of a forming IHU tool and expanded essentially transversely to the longitudinal axis with the help of a fluid introduced into the interior, for example a water-oil emulsion, whereby the pipe jacket of the starting pipe part is pressed against the cavity wall and shaped accordingly.

The publication DE 197 08 905 A1 shows especially in connection with the Figure 2 a device for internal high-pressure forming of a hollow body support, which has two tool halves between which a parting line runs.

The publication US 2014/196514 A1 discloses a hydroforming tool with four tool segments for the production of household and hardware products.

A disadvantage of the known processes and devices for internal high-pressure forming is that the components to be produced must be designed in such a way that they do not have an undercut in the closing direction of the press for closing the tool halves.

Furthermore, the coordination of the parting line between the two halves of the tool is very complex. For example, an offset can lead to a loss of quality or even to the failure of the component.

In addition, in many cases, especially when the hydroformed component has a complex shape, preforming in one or more process steps is required, whereby a preformed initial tube part is created from the initial tube part for subsequent internal high-pressure forming in the hydroforming tool. If, for example, the component cross-section tapers in relation to the blank, preforming, for example by means of immersion engraving, is absolutely necessary.

The publication DE 100 14 619 A1 shows in connection with Figure 26 a hydroforming device which has four fixed, immovable molds with concave surfaces spaced apart from one another and four movable stamp molds arranged between the fixed molds. A disadvantage of this device is, for example, that due to the fixed molds, the workpieces to be formed have to be pushed axially into the device. Due to the fixed molds coming into contact with the workpiece during forming, fixed component radii are specified. Furthermore, preforming cannot always be avoided. Coordinating the dividing lines between the fixed molds and the movable stamp molds is also very complex.

Based on the prior art, it is therefore an object of at least some embodiments to provide a method for forming a workpiece by internal high-pressure forming, by means of which a complex adjustment of the parting line can be eliminated.

This object is achieved by a method according to the independent patent claim. Advantageous embodiments and developments are further apparent from the dependent patent claims, the following description and the drawings.

In the method described here, a tool for internal high-pressure forming of a workpiece and a workpiece to be formed are provided. The tool has at least three movable tool segments which delimit a shaping cavity for receiving and forming the workpiece, wherein the movable tool segments completely form the shaping cavity at least in sections when the tool is closed.

The workpiece is formed in the tool by means of fluidic internal high pressure without any process steps for preforming the workpiece, whereby all movable tool segments (of the tool) are in direct contact with the workpiece during forming. Furthermore, when the tool is closed, two tool segments directly adjacent to each other define a parting line, whereby the workpiece has no direct contact with the tool segments in the area of the parting lines when the tool is closed. The structural component obtained by forming the workpiece has undercuts.

The workpiece can in particular be a hollow body, for example a metallic, tubular hollow body. After forming by internal high-pressure forming, the formed component can be used, for example, as a structural component for a motor vehicle.

The movable tool segments define a forming cavity for receiving and forming the workpiece. The tool can have one or more open states as well as a closed state.

When the tool is closed, the shaping cavity is completely formed at least in sections by the movable tool segments. In other words, the closed cavity is formed at least in sections solely by the at least three movable tool segments. When the tool is closed, the at least three movable tool segments can completely form the shaping cavity at least in sections in such a way that a closed, circumferential cavity outline is formed by the movable tool segments in an imaginary cross-sectional plane. Furthermore, when the tool is closed, the movable tool segments can completely form the cavity not only in sections, but across the entire cavity, so that a closed, circumferential cavity outline is formed by the movable tool segments across the entire cavity in every possible imaginary cross-sectional plane.

When the tool is closed, each of the movable tool segments is in direct contact with two other movable tool segments. When the tool is closed, the movable tool segments can each be in contact with other movable tool segments, particularly in areas that directly border the surface of the cavity, so that when the tool is closed, a closed cavity is formed solely by the movable tool segments.

The tool is further designed in such a way that when a workpiece is formed, the parting lines arranged between two movable tool segments when the tool is closed do not have direct contact with the workpiece. During the forming process, none of the parting lines arranged between two directly adjacent tool segments are in contact with the workpiece. Consequently, this can be a tool structure without a parting line. and component corner radii. Because the workpiece has no contact with a parting line, a better quality of the component to be manufactured can be achieved.

According to a further embodiment, the tool has four movable tool segments which, when the tool is closed, completely form the shaping cavity at least in sections. Preferably, when the tool is closed, the four movable tool segments completely form the entire cavity, so that in an imaginary cross-sectional plane a closed, circumferential cavity outline is formed by the four movable tool segments.

The tool described here advantageously eliminates the need for process steps for preforming the workpiece. Furthermore, the tool described here can also be used to produce components with undercuts, for example.

Figuren 1 bis 4

verschiedene schematische Darstellungen eines Werkzeugs zum Innenhochdruckumformen eines Werkstücks gemäß dem Stand der Technik, und

Figuren 5 bis 8

verschiedene schematische Darstellungen eines hier beschriebenen Werkzeugs bzw. eines hier beschriebenen Verfahrens gemäß einem Ausführungsbeispiel.

Further advantages and advantageous embodiments of the method described here for forming a workpiece by internal high-pressure forming result from the following in connection with the Figures 1 to 8 described embodiments. They show:

Figures 1 to 4

various schematic representations of a tool for internal high-pressure forming of a workpiece according to the prior art, and

Figures 5 to 8

various schematic representations of a tool described here or a method described here according to an embodiment.

In the embodiments and figures, identical or identically functioning components can be provided with the same reference symbols. The elements shown and their relative sizes are generally not to be viewed as being to scale. Rather, individual elements can be shown as being exaggeratedly thick or large for better representation and/or better understanding.

The Figures 1 to 4 show schematic representations of a tool 1 or a method for internal high-pressure forming of a workpiece 2 according to the prior art in different views. In the Figure 1 A schematic perspective view is shown. The Figures 2 to 4 show sectional views, where the Figure 2 the tool 1 in an open state, the Figure 4 the tool 1 in the closed state and the Figure 3 an enlarged section G of the Figure 2 show.

The tool 1 has a first tool segment 3 and a second tool segment 4, wherein the two tool segments 3, 4 form a closed cavity 7 in the closed state 10 of the tool 1. In the Figures 2 to 4 the workpiece 2 is shown in two different representations, namely in a representation before forming and in a representation after forming.

The disadvantage of the Figures 1 to 4 The advantage of the method shown is that the parting line formed between the tool segments 3, 4 is in direct contact with the workpiece 2 during forming. The coordination of the parting line can be very complex when designing or manufacturing the tool 1.

Furthermore, the data provided in connection with the Figures 1 to 4 The tool 1 shown does not form any components with an undercut. Depending on the component, one or more process steps in which the workpiece 2 must be pre-formed may be necessary.

In the Figures 5 to 8 various schematic representations of a tool 1 for internal high-pressure forming of a workpiece 2 according to an embodiment are shown. The Figure 5 shows a perspective view of the tool 1 and a workpiece 2 to be formed or formed. In the Figures 6 to 8 Sectional views are shown, with the Figure 6 the tool 1 in an open state, the Figure 8 the tool 1 in the closed state and the Figure 7 an enlarged section H of the Figure 6 show.

The tool 1 is designed as an internal high-pressure forming tool and has four movable tool segments 3, 4, 5, 6, which give a shape and delimit the cavity 7 for receiving and forming a workpiece 2. In the closed state 10 of the tool 1, the four movable tool segments 3, 4, 5, 6 completely form the forming cavity at least in sections, in such a way that in an imaginary cross-sectional plane a closed circumferential cavity outline is formed by the four movable tool segments 3, 4, 5, 6.

Furthermore, the individual movable tool segments 3, 4, 5, 6 are each in direct contact with two further movable tool segments 3, 4, 5, 6 in the closed state 10 of the tool 1.

When forming the workpiece 2 by means of a fluidic internal high pressure, for example by introducing a water-oil emulsion into the workpiece 2 designed as a hollow body, the workpiece 2 is not continuously in contact with the surface of the cavity 7 in the closed state 10 of the tool 1. In particular in areas of the parting lines 8 formed between 2 tool segments 3, 4, 5, 6, the workpiece 2 does not come into contact with surface areas 9 of the cavity 7.

This advantageously eliminates the need for complex adjustment of the parting lines 8. Furthermore, the risk of misalignment in the formed component due to a poorly formed parting line 8 can be eliminated.

This in connection with the Figures 5 to 8 Tool 1 shown or the one in connection with the Figures 5 to 8 The method described is also advantageously suitable for forming workpieces 2 which have an undercut. Furthermore, the tool 1 can avoid pre-forming of workpieces 2, which is absolutely necessary in the prior art.

The features described in the exemplary embodiments shown can also be combined with one another according to further exemplary embodiments. Alternatively or additionally, the exemplary embodiments shown in the figures can have further features according to the embodiments of the general description.

List of reference symbols

1

Tool

2

workpiece

3

first tool segment

4

second tool segment

5

third tool segment

6

fourth tool segment

7

cavity

8th

parting line

9

Surface area

10

closed state

G, H

enlarged section

Claims (3)

1. Method for forming a workpiece (2) for producing a tubular structural component for a motor vehicle by hydroforming, having the following steps:

   - supplying a tool (1) for hydroforming a workpiece (2), having at least three movable tool segments (3, 4, 5, 6), which delimit a shaping cavity (7) for accommodating and forming the workpiece (2), wherein, in the closed state (10) of the tool (1), at least parts of the movable tool segments (3, 4, 5, 6) fully form the shaping cavity (7),

   - supplying a workpiece (2) which is to be formed, and

   - forming the workpiece (2) in the tool (1) using high internal fluid pressure, without any process steps for preforming the workpiece, wherein, during the forming operation, all the movable tool segments (3, 4, 5, 6) of the tool (1) are in direct contact with the workpiece (2), wherein, in the closed state (10) of the tool (1), in each case two directly adjacent tool segments (3, 4, 5, 6) define a parting line, characterized in that, in the closed state (10) of the tool (1), the workpiece (2) is not in direct contact with the tool segments (3, 4, 5, 6) in the region of the parting lines and wherein, none of the parting lines is in contact with the workpiece during the forming process, and wherein the structural component obtained by the workpiece-forming operation has undercuts.
2. Method according to Claim 1, wherein, in the closed state (10) of the tool (1), the movable tool segments (3, 4, 5, 6) form a closed encircling cavity outline.
3. Method according to either of Claims 1 and 2, wherein, in the closed state (10) of the tool (1), the movable tool segments (3, 4, 5, 6) form a cavity (7), and wherein, in the closed state (10) of the tool (1), at least parts of the workpiece (2) are not in full contact with the surface of the cavity (7).

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