Tool for preforming a tube for subsequent internal high pressure forming, as well as a method for producing such a tool and for producing a component by internal high pressure forming

Abstract

A tool is provided for preforming a metallic starter tube section for subsequent internal high pressure forming in order to produce a tubular IHF-component. The tool includes a plurality of tool sections that can move relative to one another and that delimit, between them, a shaping cavity for receiving and forming the starter tube section. The cavity has a contour which is both derived from the shape of the IHF component to be produced and adapted to the circumference of the starter tube section to be formed, such that each cavity cross section perpendicular to a cavity longitudinal axis predefined by the starter tube section corresponds to the cross-sectional shape of the IHF component cross-section in the same position, reduced in its cross-sectional circumference to exactly the circumference of the starter tube section. A method is provided for producing such a tool, and a method is provided for producing a tube-like IHF component using such a tool.

Claims

1. A tool for preforming a metallic starter tube section for subsequent internal high pressure forming in order to produce a tubular IHF component, the tool comprising: a plurality of tool parts configured to move relative to one another, said plurality of tool parts between them delimiting a shaping cavity that receives and forms the starter tube section, wherein the shaping cavity has a contour both derived from a shape of the tubular IHF component to be produced and adapted to a circumference of the starter tube section to be preformed, the shaping cavity is structurally configured such that each cavity cross-section of the shaping cavity perpendicular to a cavity longitudinal axis conforms to a cross-sectional shape of the tubular IHF component cross-section, and the shaping cavity has a cross-sectional circumference that corresponds exactly to the circumference of the starter tube section.

2. The tool according to claim 1, wherein the tool is a press-based tool, and the plurality of tool parts comprise a tool underpart and a tool upper part relatively movable with respect to one another.

3. A method for producing a tool for preforming a metallic starter tube section for subsequent internal high pressure forming in order to produce a tubular IHF component, the tool comprising a plurality of tool parts configured to move relative to one another, said plurality of tool parts between them delimiting a shaping cavity that receives and forms the starter tube section, wherein the shaping cavity has a contour both derived from a shape of the tubular IHF component to be produced and adapted to a circumference of the starter tube section to be preformed, and each cavity cross-section of the shaping cavity perpendicular to a cavity longitudinal axis predefined by the starter tube section conforms to a cross-sectional shape of the tubular IHF component cross-section in a same position, but reduced in its cross-sectional circumference to exactly the circumference of the starter tube section; the method comprising the acts of: providing geometrical data determining a shape of the tubular IHF component to be produced; determining the circumference of the starter tube section to be preformed; calculating the contour of the shaping cavity required to preform the starter tube section by use of guide sections, for which purpose transverse sections are produced initially along the longitudinal axis of the tubular IHF component, and said transverse sections are then reduced in circumference to the determined circumference of the starter tube section to be preformed; and manufacturing the tool with the shaping cavity having the calculated contour.

4. The method according to claim 3, wherein the acts of providing, determining, and calculating are carried out automatically via a CAD program.

5. A tool for preforming a metallic starter tube section made in accordance with the method of claim 3.

6. A method for producing a tubular IHF component via internal high pressure forming, the method comprising the acts of: providing a starter tube section; preforming the starter tube section in a tool having a plurality of tool parts movable relative to one another and between which delimit a shaping cavity for receiving and preforming the starter tube section, wherein the shaping cavity has a contour both derived from a shape of the tubular IHF component to be produced and adapted to a circumference of the starter tube section to be preformed, and each cavity cross-section of the shaping cavity perpendicular to a cavity longitudinal axis predefined by the starter tube section conforms to a cross-sectional shape of the tubular IHF component cross-section in a same position, but reduced in its cross-sectional circumference to exactly the circumference of the starter tube section; performing internal high pressure forming of the preformed starter tube section in an IHF tool in order to produce the tubular IHF component.

7. The method according to claim 6, further comprising the act of: first bending the starter tube section prior to preforming the starter tube section.

8. The method according to claim 7, wherein the starter tube section is formed of an aluminum or steel material and has a circular or oval cross-section.

9. The method according to claim 6, wherein the starter tube section is formed of an aluminum or steel material and has a circular or oval cross-section.

10. The method according to claim 6, wherein different circumferential stretching lying within a range of between 3% and 2% is achieved over the longitudinal axis of the preformed starter tube section during the performance of the internal high pressure forming.

11. The method according to claim 7, wherein different circumferential stretching lying within a range of between 3% and 2% is achieved over the longitudinal axis of the preformed starter tube section during the performance of the internal high pressure forming.

12. The method according to claim 8, wherein different circumferential stretching lying within a range of between 3% and 2% is achieved over the longitudinal axis of the preformed starter tube section during the performance of the internal high pressure forming.

13. The method according to claim 6, wherein the preformed starter tube section is inserted into a cavity of the IHF tool such that a same distance to a cavity wall exists at every point on the longitudinal axis over a respective cross-sectional circumference.

14. The method according to claim 12, wherein the preformed starter tube section is inserted into a cavity of the IHF tool such that a same distance to a cavity wall exists at every point on the longitudinal axis over a respective cross-sectional circumference.

15. The method according to claim 6, wherein the tubular IHF component produced is a motor vehicle component.

16. The method according to claim 14, wherein the tubular IHF component produced is a motor vehicle component.

17. A tool for preforming a metallic starter tube section made in accordance with the method of claim 6.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A-1C depict, in each case, in a side view a stage of a tube-like workpiece in the course of the production of an IHF component;

(2) FIG. 2 depicts in a sectioned view a starter tube section preformed according to the prior art and inserted into the cavity of an IHF tool prior to internal high-pressure forming;

(3) FIG. 3 depicts a partial section of a tool according to an embodiment of the invention for preforming a starter tube section; and

(4) FIG. 4 depicts in a sectioned view a starter tube section preformed with the tool depicted in FIG. 3 and inserted into the cavity of an IHF tool prior to internal high-pressure forming.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 1a depicts a metallic starter tube section or starter tube piece 100. The starter tube section 100 has a constant circular cross section (in relation to the external shape) along its longitudinal axis L having the circumference U1 and a uniform wall thickness. The starter rube section 100 is made, for example, from an aluminum material or a steel material.

(6) The starter tube section 100 serves as a workpiece, which is subsequently formed into the tube-like IHF component 120 depicted in FIG. 1c produced by internal high pressure forming. The starter tube section 100 is preformed initially for this purpose, wherein only its cross-sectional shape is changed and is adapted to the contour of the cavity of the IHF tool, as described in more detail below. FIG. 1b depicts the preformed starter tube section 110, which exhibits a cross-sectional circumference U2. The respective longitudinal axis is designated with L both for the starter tube section 100 and for the preformed starter tube section 110 and the IHF component 120.

(7) The IHF component 120 is configured along its longitudinal axis L with different cross-sectional geometries, so that the cross sections differ with regard to their cross-sectional shape and/or their cross-sectional circumference. For example, the circumferential stretching that is achieved at the axial ends of the component of the IHF component 120 depicted in FIG. 1c in conjunction with internal high pressure forming is in the order of approximately 10% and approximately 3% in the central region.

(8) The IHF component 120 may, in contrast to the example depicted in FIG. 1c, have a complex, spatially multiply bent and/or curved longitudinal course, as depicted in EP 0 195 157 B1, for example. In this case in particular, provision may be made for the starter tube section 100 to be bent or pre-bent initially prior to preforming, as already explained above. The following explanations also relate to this case in an analogous manner.

(9) FIG. 2 depicts by way of example, in a schematic sectional view at the location x of the longitudinal axis L (see FIG. 1), a starter tube section 110 preformed according to the prior art and inserted into the cavity 330 of a multi-part IHF tool 300 prior to internal high-pressure forming. The preformed starter tube section 110 exhibits, at least at the indicated location, a cross-sectional geometry which approximates that of the IHF component 120 to be produced. In the course of the internal high-pressure forming, the tube casing of the preformed starter tube section 110 is pressed against the cavity wall 331 and is shaped according to the contour of the cavity wall 331 in the process, as explained by way of the introduction.

(10) During the internal high-pressure forming, a high degree of forming of the preformed starter tube section 110 takes place in the corner region identified with A, which is associated with a high degree of thinning of the casing material and possibly with the formation of a crack or a tear, whereas only a low degree of forming takes place in the region identified with B. The IHF component 120 that is produced accordingly exhibits different wall thicknesses along its circumference, which entails various disadvantages.

(11) Reference is also made below in this respect to the corresponding explanations in the prior art (see, for example, DE 10 2006 028 099 A1, paragraphs [0061] and [0062], and DE 199 46 010 B4, paragraphs [0042], [0043], [0052] and [0053]).

(12) In order to eliminate the disadvantages associated with the prior art, the cavity 230 of a tool 200 according to the invention (see FIG. 3) exhibits, for the purpose of preforming the starter tube section 100, a contour that is both derived from the shape of the IHF component 120 to be produced and is also adapted to the circumference U1 of the starter tube section 100 to be formed. It is also proposed that the cross-sectional shape of every cavity cross section corresponds in each case, along a cavity longitudinal axis L determined by the starter tube section 100, to the reduced cross-sectional shape of the IHF component cross section situated in the same position, wherein the circumference of each cavity cross section respectively conforms exactly to the circumference U1 of the starter tube section 100.

(13) This can be appreciated clearly from FIG. 1. The cross-sectional geometry for the preformed starter tube section 110 arises at the location x on the longitudinal axis L, as indicated by the arrows, wherein this cross-sectional geometry is essentially identical to the cross-sectional geometry of the shaping cavity 230 of the preforming tool 200, from the cross-sectional shape of the IHF component 120 at the same location x, and from the circumference U1 of the starter tube section 100, with the result that: U1=U2. This is also the case for every other location on the longitudinal axis L. It is generally the case that the geometry of the preformed starter tube section 110 is essentially identical to the cavity geometry 230 of the preforming tool 200.

(14) Every cavity cross section of the cavity 230 that is perpendicular to a cavity longitudinal axis L determined by the starter tube section 100 thus conforms to the cross-sectional shape of the IHF component cross section in the same position that has been reduced exactly in respect of its cross-sectional circumference to the circumference of the starter tube section 100, or is identical therewith.

(15) FIG. 3 depicts a tool 200 according to the invention for preforming the starter tube section 100 in a sectioned representation at the location x (see FIG. 1). The tool 200, when installed in a press, comprises a tool under part 220 and a tool upper part 210 that is capable of displacement relative thereto, which parts in the closed state between them delimit the cavity 230 for receiving and forming the starter tube section 100. The cross-sectional geometry of the cavity 230 at the indicated location arises as previously described. The displacement of the tool upper part 210 is indicated by the double arrow M.

(16) For the purpose of preforming, the starter tube section 100 is inserted into the cavity 230 with the tool 200 opened. The tool 200 is then closed by lowering the tool upper part 210, in conjunction with which the starter tube section 100 that is present in the cavity 230 is formed into the preformed starter tube section 110 by the application of a pressing force without a change to the circumference (i.e. U2=U1). Since the contour of the cavity 230 is adapted exactly to the circumference of the starter tube section 110, defined, accurate and compression-free forming of the starter tube section 100 takes place both at the indicated location and at any other location.

(17) The preforming process in a tool 200 according to the invention can be described as die forming, wherein this preforming is able to take place in particular without supporting pressure, and also with supporting pressure where appropriate, and in particular with low supporting pressure (so-called pressure-assisted low-pressure preforming). The preformed starter tube section 110 can be removed after opening the tool 200 and can subsequently be inserted directly into the IHF tool 300 for internal high-pressure forming.

(18) FIG. 4 depicts in a sectioned representation at the location x the starter tube section 110 preformed with the tool 200 according to the invention and inserted into the cavity 330 of an IHF tool 300 prior to internal high-pressure forming. The preformed starter tube section 110 does not bear against the cavity wall 331 of the IHF tool 300, but has a constant distance from the cavity wall 331 over its entire cross-sectional circumference, so that a circumferential and essentially uniformly wide gap S is present between the tube casing of the preformed starter tube section 110 and the cavity wall 331. Accordingly, in the case of internal high-pressure forming, the preformed starter tube section 110 is opened out and is formed essentially uniformly, as a result of which a uniform wall thickness is obtained over the circumference. The plastic circumferential stretching to be achieved at this axial location in the course of internal high-pressure forming is determined by the gap width of the gap S. The gap width of the gap S may vary along the longitudinal axis L, depending on the shape of the IHF component 120.

LIST OF REFERENCE DESIGNATIONS

(19) 100 starter tube section 110 preformed starter tube section 120 IHF component 200 tool for preforming 210 tool upper part 220 tool lower part 230 cavity 231 cavity wall 300 IHF tool 330 cavity 331 cavity wall A region B region L longitudinal axis M opening/closing movement S gap T parting plane U1 circumference of the starter tube section U2 circumference of the preformed starter tube section, or cross-sectional circumference of the cavity cross section at the same location x position (or location) on the longitudinal axis

(20) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.