EP1434659B1 - Method for producing a branch pipe - Google Patents

Abstract

The invention relates to a method for producing a branch pipe. In order for the dependable production of a branch pipe with virtually any desired design of the branch to be made possible in a simple way it is proposed that an elongate, straight main curvature and at least two lateral curvatures, respectively branching off from a longitudinal side of the main curvature, lying opposite each other with respect to the central longitudinal axis of the main curvature extending in the material of the blank and having a mirror-symmetrically arranged base line are formed from a blank by deep-drawing. After the forming operations, the blank is trimmed in such a way that a vessel-like shell part, which is open in the longitudinal direction, is formed from the main curvature, and half-sleeves, which adjoin the shell part, lie in the same plane as the shell part and are open in the direction of their extent, are formed from the lateral curvatures, and that sheet metal strips serving as joining flanges extend along the outside of the lateral edges of the shell part and the half-sleeves. Subsequently, the shell part is bent about a spatial axis parallel to the central longitudinal axis until the joining flanges corresponding to one another on both sides of the shell part lie against one another, and, after that, the joining flanges are connected to one another.

Description

The invention relates to a method for producing a branch pipe for use in the exhaust system of a motor vehicle according to the preamble of claim 1.

Branch pipes are commonly welded together deep-drawn half-shells, in one piece from cast or by hydroforming from a straight or curved tube produced. The first method of preparation requires an increased Handling effort to put the two half-shells together. In addition, two molds are required, whereby the Manufacturing tolerances of the items for the joining process accordingly are high, which makes this difficult. The execution in Casting is much easier to handle, but it is on the one hand a branch pipe made of cast iron relatively heavy and on the other hand the design variety of the branch of the to be generated Tube considerably limited in terms of wall thickness, since with the casting technique very thin walls not sure process can be formed. The hydroforming technology provides this Although there are more possibilities, there are also limits to especially as far as the length of the branch is concerned. Of others - if at all possible - due to the process-specific material thinning only very difficult and laborious, made of thin-walled pipes branches reliable to mold.

A generic method is known from EP 0 780 173 A2. This is to produce a manifold pipe branch a motor vehicle exhaust system a Blechcoil- or blank PCB deep-drawn and cut in a follow-on composite tool, whereby a pipe part semi-finished product is formed, which the unwound form of the tube part Endzeuges corresponds. The tube part semifinished product is then pre-bent and wound. The Finished bent part is bent in its medium contact area gas-tight welded.

Furthermore, from US-A-2 262 627 the preparation of a Exhaust manifold of a motor vehicle exhaust system removed, wherein two deep-drawn with branched half-shells stacked and on the flanges that protrude from the edge of the bowls connected by spot welding to an exhaust manifold become.

The invention has for its object to provide a method by means of which in a simple way the process-reliable Production of a branch pipe for use in the exhaust system of a motor vehicle with almost any design of the branch is made possible.

The object is achieved by the features of claim 1 solved.

Due to the one-piece design of the branch pipe is Handling simplified for manufacturing. The overall process of Production composed of pressing, cutting, bending, joining is easily automatable. manufacturing tolerances fall for a process-reliable production practically not ins Weight. Due to the fact that the shape of the nozzle by means of Deep drawing takes place, is the design freedom for the neck according to shape and length almost arbitrarily large. Furthermore, can Also, the wall thickness of the pipe can be greatly reduced without the process safety of it would be impaired. This On the one hand, it is favorable for lightweight construction and, on the other, in the case of Use of the branch pipe in the exhaust system of a motor vehicle advantageous for the fastest possible starting of the catalyst, because the thin wall only a small heat capacity has and thus relatively little heat extracts the exhaust stream. Due to the freedom of design, the training is strong curved branches possible, whereby in use in the assembly an exhaust manifold this better the space of the engine compartment can be adjusted. In addition, the length of the Branches can be sized so that no connecting pipe more is required to the input flange on the cylinder head. Furthermore, the joint seam is such that it is from the hot exhaust gas is not directly flowed, bringing a significant increase the durability of the exhaust manifold is associated. Due to the location the seam can, at least when used in the exhaust system the suture should be interrupted, as the gas tightness due to the in the sliding seat with game subsequent further exhaust pipes not fully given anyway what the manufacturing process times minimizes and thus the production cost-effective power.

Fig. 1 in einer perspektivischen Draufsicht eine nach dem erfindungsgemäßen Verfahren tiefgezogene und beschnittene Platine,

Fig. 2 in einer perspektivischen Draufsicht ein aus der Platine von Fig. 1 nach dem erfindungsgemäßen Verfahren gebogenes und gefügtes Abzweigrohr.

Advantageous embodiments of the invention can be taken from the subclaim; Moreover, the invention with reference to an embodiment shown in the drawings is explained in more detail below; showing:

1 is a perspective plan view of a deep drawn and trimmed according to the inventive board,

Fig. 2 is a perspective plan view of a bent from the circuit board of Fig. 1 by the method according to the invention and joined branch pipe.

In Fig. 1 is an intermediate stage of a process for the preparation a branch pipe 1 shown. To this will be initially using a blank or sheet metal section from a coil, which is subjected to a deep-drawing process. By the Deep drawing will make the board an elongated rectilinear Main bulge and two side vaults formed, which the latter branch off from one longitudinal side of the main curvature and with respect to the running in the circuit board material Center longitudinal axis 2 of the main curvature opposite each other. The side curvatures are in terms of shape of their baseline arranged mirror-symmetrically to each other. The baseline denotes the course of the opening edge of the side curvatures. Although in the embodiment shown, the side curvatures the form and dimension according to - apart from their mirror-symmetrical arrangement - are completely alike, can the side bulges also according to the desire of the produced Branches have different depths.

After forming the board, this is in procedural economic Way in the thermoforming tool by means of a punching tool or outside the thermoforming tool in a jig by means of a three-dimensional feasible Cutting laser cut. The trimming results on the one hand, a tub-like shell part 3, the main bulge arises and is open in the longitudinal direction. The shell part 3 is rectangular in a plan view. It However, for example, in one or both directions of Longitudinal extension of the shell part 3 as a uniform Trapezoid be designed. Close to the shell part 3 in the same plane lying half-pin 4, which from the Side curvatures result. The half-stubs 4 are in Extension direction open and in each case as a half circular cylinder educated. The geometry of the rectilinear parallel But lower edges 5 of the half-4 can also be completely different. For example, these can be curved or be formed rectilinearly converging to each other. In In the latter case, the half-pin 4 has the shape of a half-cone. The half-stubs 4 open into the one of the curvature formed cavity 6 of the shell part 3. Furthermore, are on the shell part 3 and the half-4 sheet metal strip. 7 formed in the same plane as the lower edges 5 of the half-pieces 4 and the lower edges 8 of the shell part 3 lying outside on the lateral edges 9 of the shell part 3 and the half-4 extend along. The Sheet metal strip 7 of the shell part 3 and the half-socket 4 are but connected together, but also from each other be separated. It is also not an inevitable requirement that the metal strips 7 over the entire surface in the same level as the lower edges 5 of the half-pieces 4 and the lower edges 8 of the shell part 3 must be located. Of the Sheet metal strip 7 must for the success of subsequent joining operations in any case starting from this level, with deviations from the above education at the same time the re the central longitudinal axis 2 opposite each other Sheet metal strip 7 must be formed form negative to each other. This is advantageous in that in the subsequent Bending the sheet metal strips 7 positively into one another grip, thus providing a better grip for the joining operation and ensures improved durability of the joint seam. The metal strips 7 serve here as Fügeflansche.

Subsequently, in a separate tool via a bending mandrel the shell part 3 about a parallel to the central longitudinal axis 2 Space axis 10 bent, an axis that in a the Shell part 3 along the central longitudinal axis 2 in the normal direction piercing plane lies and from the middle longitudinal axis 2 is spaced (Fig. 2). In the illustrated embodiment is the axis 10 is the radius of the formed by bending circular cylindrical main pipe 11 from the central longitudinal axis 2 offset down. The bending takes place, until the one another on both sides 13,14 of the shell part. 3 corresponding Fügeflansche 7 over the entire surface together. In each case, the lower edges 8 of the shell part come for themselves 3 on the one hand and the lower edges 5 of the half-4 on the other hand lie on one another, whereby from the shell part 3, said main pipe 11 and the half-stub 4 of Branch pipe 12 is formed, which together in turn the Form branch pipe 1.

Finally, in a final manufacturing step, the Joining flanges 7 connected together. Through the training of flanges 7 is only the Punching made possible what the durability the joint seam 15 favors considerably and is sensitive to heat Materials is beneficial.

The metal strips 7 are formed in the present example so that the end 16 of the half-strip 4 running along the metal strip 7 is withdrawn with respect to the opening edge 17 of the half-piece 4. The same applies to an end 18 of the shell part 3. This ensures that the branch pipe 1 can easily pass simple connections with other pipes or connections. For example, in the exhaust line of the branch pipe 12 can be easily plugged together with the input flange of the cylinder head and optionally welded to the flange, while the main pipe 11 can be connected to another pipe of an exhaust manifold in the sliding seat. To form an air gap-insulated exhaust manifold, the branch pipe 1 can be plugged and welded as an inner part with the corresponding nozzle of the outer shell.
Moreover, the solution according to the invention is not limited to the formation of a single branch pipe 12. In the case of longer shell parts 3, it is certainly possible to form a plurality of side curvatures or half-pieces 4 in the deep-drawing process, which then form branching branch 12 after completion of the production process. These can be formed with respect to shape and length depending on the requirements of the spatial and / or fluidic conditions with each other the same or different.

Claims (2)

1. A process for the fabrication of a branch pipe (1) for use in the exhaust train of a motor vehicle, whereby

   a long, straight principal curved section and at least two lateral curved sections which lie opposite one another in relation to the central longitudinal axis (2) of the main curved section which runs through the billet material, are positioned mirror symmetrically in relation to a base line and branch off from the longitudinal sides of the main curved section are formed from a billet by means of deep drawing,

   after forming, the blank is trimmed in such a manner that a longitudinally open, trough-like shell part (3) is formed from the principal curved section and half connection pieces (4) which are open lengthwise and lie in the same plane as and adjacent to the shell part (3) are formed from the lateral curved sections, with metal strips (7) which extend along the outside of the lateral edges (9) of the shell part (3) and the half connection pieces (4) serving as joining flanges,

   the shell part (3) is then bent about a spatial axis parallel to the central longitudinal axis (2) until the corresponding joining flanges (7) on either side (13, 14) of the shell part (3) lie adjacent to one another,

   following which the joining flanges are connected together,

   characterised in that
   the joining flanges (7) are connected together by means of clinch joining.
2. A process in accordance with claim 1,
   characterised in that
   the end (16) of the metal strip (7) which runs along the half connection piece (4) lies set back in relation to the opening edge (17) of the half connection piece (4).

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