FR2846580A1 - Production of silencer or catalytic converter box with connection with smaller section at at least one end to integrate it into exhaust pipe of vehicle - Google Patents

Abstract

A tube (3), in particular a cylindrical tube, is closed at the end (2, 5) of the box (1) and the connection (11, 12) is made at the level of or near the closed end of the tube by perforation and drawing out. The end of the tube is closed by fluoturning or by deep stamping. After the end is closed, a reinforcing cone is introduced from the other end to define a heat insulating layer of air at the end of the tube. After one end is closed and the connection stub is made, the other end is closed by fluoturning after introduction of a catalyst or the parts of a silencer and a second stub is formed by perforation and drawing near the other closed end of the tube. The drawing is done from inside or outside the tube. The fluoturning operation to close at least one end of the tube is done hot, heating by induction. The drawing operation is assisted by an expandable rotating mandril introduced into the tube after perforation. At the other end of the tube, a cone opening into a smaller section connection stub is formed by fluoturning or is welded on.

Description

The invention relates to a method of manufacturing a

  casing of silencer or catalyst, which comprises at at least one of its ends at least one connecting end piece having a smaller section than said casing and allowing the integration of the latter in a motor vehicle exhaust line .

  The present invention will therefore find its application in the field of manufacturing by forming a tube, intended for use in the automotive sector, in particular to serve as the outer casing of a silencer or an incoming catalytic converter. in the composition

an exhaust line.

  It is known to design such tubular envelopes, terminating at their ends by an inlet cone and an outlet cone opening out through a section of tube of reduced diameter, either by a mechanical welding process, or

by flow turning.

  In the first case, this envelope results, for example, from the stamping of two half-shells which are just assembled by welding at the height of a joint plane, or from the

  welding of two cones on the ends of a section of tube.

  The flow-turning solution not only leads to products with a lower cost price, because requiring a

  less manufacturing time, but also more resistant.

  In particular, it is known from document EP-A0,916,428 such a method and apparatus for the flow forming of cylindrical envelopes intended for the design of a

  silencer or catalytic converter.

  In this regard, if, by flow spinning, it is common to act on the section of the part so that it has parts of more or less large diameter, the part finally obtained generally retains its symmetry by

relative to its initial axis.

  However, precisely, in this field of muffler or catalyst casings and because of the constraints of setting up an exhaust line on a motor vehicle, the connection end piece at the inlet cone or that of the outlet cone must very often have a different orientation relative to that of the axis of the envelope. In this document EP-A-0.916.428 the process and the apparatus described aim, precisely, to obtain

  such envelopes meeting the above constraints.

  In particular, during the flow spinning operation, provision is made to impart to the envelope, by means of first 10 drive means, a translational movement essentially in a direction perpendicular to the axis of this envelope for, through the flow-forming tool, shift and offset the tip opening out from such a cone

entry or exit.

  The solution described in this prior document also makes it possible to give this envelope a rotational movement about an axis which is perpendicular thereto in order to give this opening nozzle a different orientation, so that its

  axis is no longer parallel to the axis of the envelope.

  The pivot axis given to the envelope is determined by

depending on the desired result.

  However, it turns out that despite the multiple relative mobilities of the casing with respect to the flow-forming tool, it is not possible to obtain a casing for a silencer or even a catalyst which can be suitable for all situations. installation of an exhaust line

motor vehicle.

  In particular, if we consider that the axis of this envelope is located in a horizontal plane, after deformation 30 the axis of the connection piece of an inlet cone or an outlet cone is located necessarily himself in a plane

horizontal parallel.

  In soime, this axis of said connection end piece cannot

  intersect on the horizontal plane of the axis of the envelope.

  Thus, although having certain advantages compared to mechanized welding, the flow spinning process does not make it possible to obtain a connection end piece whose axis has with the general axis of the tube from which it comes, an angle

greater than 300.

  The present invention aims to provide a solution to this problem, in particular to the difficulties which may be encountered through currently known solutions for orienting, suitably, the end-piece emerging from an inlet cone or output in all directions from

the axis of the envelope.

  Thus, through the present invention, we are able to satisfy a greater number of specific situations encountered in the context of the design.

  silencer casings or catalytic converters.

  Therefore the invention also makes it possible to reduce, even more, the mechanically welded fabrications which, as has been explained above, are not satisfactory for

various reasons.

  To this end, the subject of the invention is a method of manufacturing a silencer or catalyst casing 20 comprising at at least one of its ends at least one connecting piece of smaller cross section for its integration into a line d motor vehicle exhaust, characterized in that, starting from a tube, more particularly of cylindrical shape, the latter is closed at said end, in particular by flow turning or by deep drawing, and by perforation and drawing, said connection end piece at or near the level

  of this closed end of said tube.

  According to a first possibility of implementing said method, after closing one end of the tube and making the connection end piece, the other end of said tube can be closed, by flow spinning or the like, if necessary. after introduction of a catalyst body or of the components of a silencer, and at least one other connecting end piece can be produced by perforation and drawing at this other closed end of said tube. According to a characteristic of the present method, said stretching is carried out by proceeding from the interior of said tube. According to another embodiment, said one is produced

  drawing by proceeding from the outside of said tube.

  Furthermore, the present process is also characterized in that for the closure of at least one of the ends 10 of said tube, the procedure is by flow spinning. advantageously,

  this flow-forming operation is carried out hot.

  In this regard, if it is possible to heat by means of a flame burner, this flow-turning operation is carried out,

  preferably by heating by induction.

  According to an additional characteristic, the drawing operation is carried out using an expandable rotary mandrel

  introduced into said tube after perforation.

  According to another characteristic, the said method also provides that at the other end of the said tube, a cone opening out by flow turning is produced through a nozzle.

  weaker section connection.

  It is also conceivable, according to an additional characteristic, to report by welding, at the other end of said tube, a cone provided with a connection end piece. Thus, thanks to the present invention, making it possible to form a connection end piece whose axis has an angle of unlimited value with the axis of the tube, it is possible to adapt its orientation relative to the constraints encountered, and to designing catalyst or silencer casings for motor vehicles capable of integrating perfectly into an exhaust line, without requiring the use of a mechanized welding process, as is currently the case.

  The invention will be better understood on reading the description which follows, referring to examples of

  realization given as an indication and not limiting.

  The understanding of this description will be facilitated at

  seen from the appended figures in which: - Figure 1 corresponds to a schematic perspective view of a casing of silencer or catalyst as obtained by the implementation of the present process, Figures 2 to 5 represent different modes of

  implementation of the successive stages of the present process.

  The present invention relates to a method of manufacturing casings 1 for catalysts or silencers for motor vehicles, by means of which it is possible to form connection end pieces going in the appropriate direction for perfect integration into an exhaust line, without there are no conformation limitations as it is

  generally the case with conventional methods.

  Thus, the present method provides, in a particularly advantageous manner, to close, firstly, by flow turning or by deep drawing, as has been described, for example, in document DE-197 34 198, a first end 2 of a tube 3 having a section, for example of cylindrical shape. Through this, it can be

  imparted to this end 2 of this tube 3 a variable shape. In particular, it can be defined in a substantially ovoid shape 4, as illustrated in the figures of the drawings, just as it can have a cross section in the manner of a flange.

  According to a characteristic of the present method, provision is made, in the case of flow forming, to carry out this hot operation, on the one hand, in order to avoid damaging the tube 3 under the effect of the stresses implied by this step. and, on the other hand, to obtain a complete and hermetic closure of the end 2 of the tube 3 by welding thanks to the thermal energy supplied. To this end, the method provides for heating this end 2, preferably by induction. However, any other heating means, in particular a flame burner, can

also agree.

  It will be noted that after closing this end 2 of the tube 3, it can be introduced into the latter, from the other end 5 and before the engagement of a catalyst body 6, a lining cone 7, as this has been shown schematically in FIG. 3. It is thus possible to define thermal insulation with an air space 8 to

said end 2 of this tube 3.

  In a second step, a perforation is made, using an appropriate tool 9, 9A, in the vicinity of this end 2, 10 at the location on which it is desired to form a connection piece, it being specified that this end 2 of the tube 3 can, if necessary, receive several connection end pieces. This may be the case, for example, for a

  catalyst intended to be placed just downstream of an engine manifold.

  The opening 10, thus produced and traversing, the case

  where appropriate, the lining cone 7 is then stretched until a connection end piece 11 is obtained which has a shape, dimensions and orientation which are perfectly suited to its integration into the exhaust line considered.

  By proceeding in this way, it is particularly easy to produce a connecting piece 11 whose axis Y forms with the axis X of the tube 3 an angle a of unlimited size, and

  can quite present more than 300.

  To obtain a given angle, it suffices in fact to perforate said end 2, in this case in the context of the embodiment illustrated, the ovode zone 4 or its vicinity, at the corresponding location, before stretching the opening. 10

thus carried out.

  It is of course possible to shape a connection piece 12 at the other end 5 of the tube 3, after having however introduced, inside the casing 1, the catalyst body 6 or the complementary components,

  such as baffles or others, of the silencer.

  This second connection endpiece 12 can be produced in the same way as the first, by first closing, in particular by f luotournage, said other end 5 of the tube 3, then by stretching an aperture 10 perforated beforehand

  appropriate, so as to obtain the desired orientation.

  Said method can be implemented in different ways to obtain such results. In particular to perforate the tube 3 at one of its

  ends 2, 5 closed or in the vicinity of the latter, one can proceed by punching as visible in FIG. 2.

  The tool 9, a punch 13 in this case, acts from the outside in cooperation with a counter punch 14 previously introduced into the tube 3, from the other end 5, 2 which remains open. We can still imagine acting from the inside by means of the punch, the counter-punch taking

  position in this case on the outer side of the tube 1.

  To make the opening 10, it is also possible to use a rotary perforating tool 9A, in particular a

  drill as shown in Figure 3.

  The opening 10 designed by punching or using a drill has, at this stage of the process, a cross section smaller than that of the connection end piece 11, 12 that is sought.

ultimately to achieve.

  As for the stretching step of this opening 10, it can, again, be carried out in different ways as visible

in Figures 4 and 5.

  In particular, it is possible to act from inside the tube 3 using a tool 15, in particular a punch 16, of section greater than that of the opening 10. Externally and in the vicinity of the latter takes up position, while previously conne, a counter punch 17, in the form of a matrix. Thus, the metallic material is stretched and pushed back simultaneously towards the outside of the tube 3, to form a connection end piece 11, or 12 of desired diameter. Furthermore, it is also possible to carry out this stretching from the outside of said tube 3, as shown diagrammatically in FIG. 5, in order to obtain a completely comparable result. In this case, the tool 15A for carrying out this stretching operation is preferably defined by an expandable rotary mandrel 18 introduced inside the tube 3 through this opening.

  already perforated in one closed end 2, 5 of the tube 3.

  This mandrel 18 allows, finally, to deform the metal 5 to create a connecting piece 11, 12 of shape, size, and orientation in accordance with the constraints

  of locations initially identified.

  Of course, the present process does not however exclude

  to use, for the design of at least one of the connection ends 11, 12, to the traditional methods and tools.

  Thus, it is entirely conceivable to produce, at a first end 2 of the tube 3, a connection end piece 11, 12 in accordance with the steps just described, and then to continue at the second end 5, not yet modified, in order to produce, for example by flow-turning, a cone opening out through a connection end piece

lower section.

  In the same spirit, it is still possible to report,

  by welding, on this second end 5, a cone provided with a connection end piece.

  It is therefore clear from the above that the present process makes it very simple to resolve the various drawbacks described above, and to considerably widen the range of envelopes for catalyst or silencer, produced by flow spinning, and intended to be integrated into motor vehicle exhaust systems, both in terms of their structures and

  of the conformation of the latter.

  Although the invention has been described with reference to some particular embodiments, it is understood that it is in no way limited thereto and that there can be made various modifications of shape, materials and combinations of these. various elements, without departing from the scope and spirit of the invention. 35

Claims (10)

  1. Method of manufacturing a casing (1) of silencer or catalyst comprising at least at one of its 5 ends (2, 5) at least one connection end piece (11, 12) of smaller cross section for its integration in a motor vehicle exhaust line, characterized in that, starting from a tube (3), more particularly of cylindrical shape, the latter is closed at said end (2) and is produced by perforation and stretching , said connection end piece (11) at or near this end (2) closed of said tube (3).   2. Method according to claim 1, characterized in that said end (2) of the tube (3) is closed by flow spinning 3. Method according to claim 1, characterized in that one closes at said end (2) the tube (3) by deep drawing.   4. Method according to one of claims 1 to 3,   characterized in that, after closing one end (2) of the tube (3), there is introduced into the latter, from the other end (5), a lining cone (7) so as to define a thermal insulation to air knife (8) at said end (2) of this tube (3).   5. Method according to one of claims 1 to 4,   characterized in that, after closing one end (2) of the tube (3) and making the connection end piece (11), the other end (5) of this tube (3) is closed by flow spinning, the if necessary after introduction of a catalyst body (6) or the components of a silencer, and another connection end piece (12) is made by perforation and stretching.   level of said other end (5) closed of said tube (3).   6. Method according to one of claims 1 to 5,   characterized in that said stretching is carried out by proceeding from the interior of said tube (3).   7. Method according to one of claims 1 to 5,   characterized in that said stretching is carried out by proceeding from the outside of said tube (3).   8. Method according to one of claims 1 to 7,   characterized in that the flow spinning operation for closing at least one of the ends (2, 5) of said tube (3) is carried out hot.   9. Method according to claim 8, characterized   in that the flow spinning operation is carried out by heating by induction.   10. Method according to one of claims 1 to 9,   characterized in that the stretching operation is carried out using an expandable rotary mandrel (18) inserted in said tube (3) after perforation.   he. Method according to one of claims 1 to 3,   characterized in that at the other end (5) of said tube (3), a cone opening out through flow-forming is produced   a connecting piece of smaller section.   12. Method according to one of claims 1 to 3,   characterized in that at the other end (5) of said tube (3), a cone provided with a connection end piece is attached by welding.