EP1233837A2

EP1233837A2 - Method for forming an initial profile or a tool of the kind and a profile therefor

Info

Publication number: EP1233837A2
Application number: EP00971201A
Authority: EP
Inventors: Christian Leppin; Markus Gehrig
Original assignee: Alcan Technology and Management Ltd
Current assignee: 3A Composites International AG
Priority date: 1999-11-18
Filing date: 2000-11-08
Publication date: 2002-08-28
Anticipated expiration: 2020-11-08
Also published as: WO2001036121A3; DE19955694A1; ES2203523T3; ATE246059T1; US6810705B1; DE50003146D1; WO2001036121A2; EP1233837B1; CA2391444A1

Abstract

A process for forming a starting profile with a profile cavity by a bending forming process and an internal high pressure produced in a sealed profiled cavity by way of a fluid, including the steps of initially, before forming by internal high pressure, forming a starting profile at a distance from free ends of the starting profile and across a longitudinal axis of the starting profile into a cross-section with favorable bending properties, by one of transversely inwardly bent side walls of the starting profile, folding during bending, flat pressing or a flat high-sided profile produced in an extrusion process.

Description

Method for reshaping an initial profile or the like Workpiece and profile for it.

^ The Drfincung applies to a process for reshaping a - initial prof. 3 or the like. Workpiece by means of an Inπe- .ochαruckes generated in the sealed profile space by a currentable active medium to form an end profile, in particular for. iforren c_s for placing the end profile on the wall 10 of a wall. In addition, the invention captures a profile with at least one profile and a limited profile space as a standard profile for carrying out this method.

In ¹ so-called Inr.er.nochαruck-Forming (IHU-entangle), an internal roll profile is expanded by internal pressure. In addition, the hollow profile can be pushed and widened, compressed, or compressed by means of at least one stamp acting on the workpiece. expanded.

20 DE 35 32 -99 Cl is an example of a device for - Apply a pipe section using a m aas?: nι insertable cone-like cylindrical probe, which m_ttels at least two spaced apart diameter with the pipe section to be widened-

25 section forms a space which is filled with pressure medium to expand. Before the start of the processing, αie beioen sealing rings are sealed radially with pressure medium D to seal the annular gap between the probe and the tube. D_e pressure medium supply to the annulus takes place via

30 at least one Aufnahmenut and is controlled by a .orper d__enerαen sealing ring that closes an opening located between the receiving groove u ~ α Rmgraum so long that it has achieved its sealing effect by elastic expansion.

35 This hydroforming or hydroforming is becoming more and more popular as an economical manufacturing process for body components in the automotive industry. Steel pipes are predominantly used as the starting material. Recently, aluminum materials have also been added to IHU processes as the starting material for steel. Analogous to steel, there are manufacturing processes that use aluminum sheet tubes as starting material; alternatively, extruded aluminum profiles can also be used. Steel is not an option for economic reasons. The use of extruded profiles has the decisive advantage that there are almost no limits to the design of the initial profile.

In the case of "bending shapes of metallic tubes or extruded profiles, attempts are generally made to design the bending process in such a way that the initial cross section of the workpiece is preserved in the then curved workpiece. Formation of folds on the inner radius or foldings on the outer radius must be prevented. Various techniques have been developed to achieve this goal, some of which are exemplified:

• stretch bending;

• bending over a mandrel;

• hot bending.

In the case of curved hydroformed components, for the manufacture of which a bending process is intended prior to hydroforming, such bending techniques are used.

Knowing these circumstances, the inventor has set himself the goal of an alternative bending method for hydroforming components, in which the intention is deliberately to avoid shaping or maintaining the shape in the bending forging process that comes as close as possible to the contour of the cross section that is ultimately to be shaped. The teaching of the independent claim leads to the solution of this task; the subclaims indicate inexpensive further training. In addition, all combinations of at least two of the features disclosed in the description, the drawing and / or the claims fall within the scope of the invention.

Erfmαungsσemaß before forming by internal high pressure, the Ausgaπgsprofll m at a distance to its free ends and transverse to its longitudinal axis to a cross section with favorable bending properties, in particular a flat DZ ... approximately oval cross section. For this purpose, it has proven to be advantageous to associate the starting profile with the area to be deformed, for example extruded from a light metal alloy or bent and joined from a sheet metal, and to deform it by means of this cross section - in addition, the starting profile is to be changed after the cross-sectional shaping this area be bent.

It is within the scope of the invention to mount the initial profile on a stationary tool and to deform and bend it in cross-section as well as to bend it by means of a counter-tool which can be moved in a translatory and rotary manner.

An advantageous starting profile for the procedure according to the invention is of approximately H-shaped cross section with two approximately parallel and interconnected chambers. Their flank walls are supposed to be curved inwards in cross-section, whereas the inner boundaries of the chambers are formed by channel-like indentations.

In the present case, it is a combined bending hydroforming process for which there are in principle no limits to the choice of the starting material; in the latter case it may be aluminum, steel or other metals, given ^¬ possibly also to non-metallic materials. Following in grain B ation bending process methods that can be used with hydroforming processes can be distinguished here:

• an upstream deformation to a cross-section with favorable bending properties;

• an accompanying forming into a cross-section favorable for bending during the bending process;

• A design of flexible cross sections for extruded profiles - preferably made of an aluminum alloy - without an upstream or accompanying forming process.

The inventor deliberately enforces folding or he flat prints the workpiece; if necessary, he designs extruded profiles already in the initial state as flat upright profiles in order to achieve a low flake moment of inertia in this way, so that correspondingly small plastic distortions result in the bending forging process. Only in the subsequent IHU process is the workpiece shaped to its final shape.

There is a clear separation of tasks in the combination of bending and hydroforming process according to the invention:

• the bending process of Formge ^¬ serves environment of the component center line,

• The IHU process serves to shape the cross-section. This is less to simplify the technical effort involved in bending than to minimize the degree of deformation. In the bending process according to the invention, the degree of deformation achieved is significantly reduced compared to a bending process according to a method taken from the Star.ce of technology. This means that with a classic bending technique, in which the bending process already strives to achieve a cross-sectional contour that is as close as possible to the desired end result, favorable results can only be obtained in exceptional cases m in relation to the accurately corrected plastic distortions at the end of the entire process sequence achieve. In contrast, when the bending strategy according to the invention is used, the lower degree of deformation in the subsequent hydroforming process means that a higher residual forming capacity is available.

The bending process according to the invention for the production of IHU-3 components offers considerable advantages.

• With the same material, larger deformations can be realized in the IHU process, i.e. there is greater freedom in the design of the final contour of an IHU component;

• IHU components with much smaller bending radii with the same cross-sectional dimensions are possible. Further advantages, features and details of the invention are given. from the following description of preferred exemplary embodiments and with reference to the drawing; this shows m:

Fig. 1: an oblique view of a curved

Square profile;

2, 3, 4: three sketches for steps of one

Bending process as well

5: an enlarged oblique view of the product of the bending process;

6, 7: two sketches for a calculation process;

Fig. 8, 9, 10: πever a cross section through

Preliminary profile for the manufacture of the square profile;

11: an oblique view of a preliminary profile with the cross section of FIG. 10;

Fig. 12 to 15: vιer sketches on the sequence of the Ausfor ^¬ formation of the square profile.

Of a rectangular tube 10 the width b of 80 mm and the Querschnittsnohe h mm of 50 is during a gear with Biegevor ^¬ anschließenαem hydroforming process, a - at right angles to one another extending tube sections llq. 11t-removing elbow 11 with an inner bending radius R_ of 200 mm. The 2 ois 5 illustrate the bending of a tubular profile 10 _a round cross-section to an elbow ll _a with a KrümungsΛ'_nkel q of 90 °; in the course of this method, that tube profile 10 _{a is} inserted between two roller-like tools 12, 12 _{r in} such a way that it is tangent to a tool 12 of this pair of tools somewhat outside its long center, after which the other tool _2 _r acts as a counter-tool in the closing direction x translat-sch the pipe profile 10 _{a is} brought up. The bewegcare tool 12 now begins a _r rotaviruses tionsπch _ ⁿ gy its way to the stationary die 12 and receives daDe_ the top in Figures 2 to 4 tube section ll with _q from αer longitudinal axis A of the tubular profile 10 _a. -

The Darste_lung of Fig. 5 reveals that the genes tube profile 10, during the bending process in the contact area has been dented to the standing tool 12. This deformed area G determines with the end edges 13 of the tubular profile 10 _α or the elbow ll _α distances e, ei. Its vertical line is marked with M.

The manufacturing process was based - with reference to FIGS. 6, 7 - on the following theoretical considerations. D profile section 14 in the initial state according to FIG. 5 has the local radius of curvature R ^ and is bent into the final state 14 _a according to FIG. 3 such that the radius of curvature R _{mB is} established in this final state; the two radii of curvature R ^ and R _mB each refer to the bend-neutral fiber of the cross section. Assuming that there is no change in cross-section during bending, sιc ^π for the elongation ε _z at any point at a distance z from gener neutral fiber:

l _zA , l _B are the _lengths before and after the bending process, wi the angle which the pipe or profiled section 14 includes before bending, and w ₂ the angle included after bending by the profile section 12 _a .

In the case of a bend - without a superimposed stretching - the length of the neutral fiber remains constant:

W2RmB = WlRmA

After inserting and reshaping you get

for the strains at any point at a distance z from the neutral fiber. For the special case of an uncurved starting material (R ^ = ∞) this results

Extreme values of the elongation ε _z arise for extreme distances z to the neutral fiber. For symmetrical cross sections with a width b, z _nax = b / 2 and thus

Equations (1) to (3) can be used to estimate the expansions occurring in a tube or profile 14 - including the maximum expansions - in the case of bending deformation under the given conditions. For example, a tubular profile 15, indicated cylindrically in cross section, of diameter d of 80 mm and a wall thickness t of 2 mm is to be bent before an IHU process in such a way that an inner bending radius R of 200 mm results. In a normal bending process, the maximum elongation at the outer radius can be estimated according to equation (3) above. With the given output variables

b = d = 80 mm; RmA = ∞, RmB = d / 2 + 200 mm = 240 mm

εmax = 16.7%.

In order to reduce the maximum strains occurring in the bending process, the cross-section of the ring is deformed before the bending process in such a way that an elliptical cross-section of height I of 112 mm and width n of 48 mm approximates with the main axes indicated at Ii and Q. results. The cross-sectional area of the elliptical profile 15 _a from here 251.30 mm remains the same as that of the circular tube or tubular profile 15.

In the apex αes elliptical cross-section results in a curvature or SiCN vertex radius r of 10 mm and - as ge ^¬ says - a total width n after beschrieoenen deform mencen Emdellen of only 48 mm.

Through this embedding of the tubular profile 15, a load maximum is created in the apex of the cross section. Here, too, the resulting maximum strains can be estimated using equation (3); With

b = t = 2 mm; RmA = d / 2 = 40 mm; R _m B = r = 10 mm is obtained as a result of that Emdellens the tubular profile or tube 15 at the apex of the resulting profile 15 _a elliptical cross-section a maximum circumferential extension of

Due to the reduced width of n = 48 mm, the lengthening on the outer radius in the longitudinal direction in the subsequent bending process is only ε _ma = 10.0%. With a bending process in which the tube cross-section is deformed beforehand, the maximum elongation can thus be reduced by about half compared to conventional bending techniques.

Since the use of a circular cross-section in the bending process thus leads to a comparatively high degree of deformation, it is better to choose an elliptical cross-section here, which in turn is unfavorable for loading an IHU tool indicated at 30 in FIGS. 12 to 15; this tool 30 cannot then be closed without crushing the pre-bent workpiece or profile 14 _a .

With an optimized pre-profile 16, which is similar in cross section to an "H" in FIG. 10, the same degree of deformation is achieved during bending as with the elliptical cross section. In addition, however, the bent workpiece can be inserted into the hydroforming tool 30 without any problems.

The posed or folded pre-profile 16 of the height iχ of 50 mm and the width n _x of 48 mm is - as I said - cross-sectionally H-shaped with two lw parallel vertical chambers 18, the outer flank walls 20 of which are curved inwards to the horizontal main axis Q. The inner chamber walls 22 are sections of bead-like deformations 24 of the bottom wall 26 and the ridge wall 28 of the preliminary profile 16. The distance s between the deepest of the two deformations 24 corresponds to approximately one sixth of the profile height iχ. Both the width ni of this Fig. 11 Schrag view to be taken preliminary section 16 as well as its scavenging Querschnittsum- corresponding to the respective dimensions of the elliptical profile 14 _a of Fig. 9.

According to FIG. 12 m, the pre-profile 16 produced by extrusion is inserted the tool 32 consisting of lower tool or base part 30 and upper tool or cover part 36. This only outlines the contours of the tool surface of the lower tool 32 with bottom wall 33 and side wall 34 and of the upper tool 36 which are relevant for the forming process.

13 shows the step of widening the preliminary profile 16 by means of a pressure medium flowing into its interior 19. In the course of this printing process, the preliminary profile 16 of the bottom wall 33 and the side walls 34 of the lower tool 32 and the upper tool 36, which is stored in the tool space 38, lies against the inside. The expansion of the bottom wall 26 and ridge wall 28 is quite slight; the preliminary section 16 unfolds through pressure medium flowing into its interior 19 - almost corresponding to an accordion - and in this way fills the tool space 38. The walls 20, 26, 28 of the profile 16 are not stretched until the end of the unfolding process when the tool space 38 is formed.

The square tube 10 or angle piece 11 produced in the tool 30 in the manner described is then removed from the tool space 38 (FIG. 15).

Claims

PATENT CLAIMS

Method for forming an initial profile or the like having a profile space. Workpiece by means of a m the sealed. Profile space generated by an internal high pressure through a fluid active medium to form an E dprofile, in particular for forming until the final profile rests on the wall of a molding space,

characterized,

that before forming by internal high pressure, the initial part (10, _10a , 15, 16) is formed into one at a distance from its free ends (13) and transversely to its longitudinal axis (A). Cross section is formed with favorable bending properties.

Method according to claim 1, characterized in that during the bending process the center line of the component is formed and its cross section is deformed by internal high pressure.

Method according to claim 1 or 2, characterized in that the initial profile (10, 10 _a , 15, 16) with the area (G) to be deformed is assigned to a tool (12, - 2 _- and is narrowed in cross section by this.

Method according to claim 1 or 3, characterized in that the initial profile (10, 10 _a , 15, 16) is formed by extrusion.

Method according to claim 1 or 3, characterized in that the initial profile (10, 10 _a , 15, 16) is bent and joined from a sheet of metal.

6. Method according to one of claims 1 to 5, characterized in that the initial profile (10, 10 _a , 15, 16; is bent around this area (G) after the cross-sectional deformation.

Method according to claim 3 or 6, characterized in that the output profile (10 _a ) is mounted on a standing tool (12) and by a counter tool (12 _r ) which can be moved translatively (x) and rotationally (y). is deformed and bent cross-sectionally.

5. The method according to any one of claims 1 to 7, characterized in that the initial profile ( _10a , 15) is deformed in a region (G ^' to a flat, possibly approximately oval cross-section.

9. Profile with a profile space delimited by at least one profile wall as a starting profile for carrying out the method according to at least one of the preceding claims, characterized in that the profile (16) has an approximately H-shaped cross section and at least two approximately parallel and interconnected chambers (18 ) having.

10. Profile according to claim 9, characterized in that the flank walls (20) are bent inwards in cross section (Fig. 10..

11. Profile according to claim 9 or 10, characterized in that the internal boundaries (22) of the chambers (18) are formed by channel-like indentations (24) on the bottom and ridge surfaces (26, 28).

12. Profile according to one of claims 9 to 11, characterized in that it is an extruded profile or a profile (16) made from sheet metal.