EP0949977B1 - Method for the crosswise shrinking of a cylindrical part in a tubular part and assembly of two corresponding parts - Google Patents

Description

The present invention relates to a method for press fitting of an at least locally cylindrical part in a tubular piece, generally transversely by with respect thereto, according to the preamble of claim 1, as well as an assembly formed by two pieces fitted crosswise, according to the preamble of claim 10.

By at least locally cylindrical part is meant here a part whose outer surface is, at least locally, at the level of its fitting with the tubular part, a cylindrical surface, i.e. a surface which, whatever the nature, circular or otherwise, of the outline of its cross section, is formed of parallel generatrices.

This at least locally cylindrical part, which, by measuring convenience, will be hereinafter more simply cylindrical part, can be solid, hollow or tubular.

In the case of a hollow or tubular part, it can serve as housing at least any other component.

As a corollary, one hears here, by tubular part, a part, which, all by being generally elongated in the form of a tube, by being open to one at less of its ends, can be more or less conformed, being by more or less curved or curved example, and which, transversely, presents any section.

The assemblies formed of a cylindrical piece fitted in a cross in such a tubular piece can find for themselves their own application, in particular because of the particular assembly of the parts which constitute, but they can also find their application in the assembly of other components linked to one or other of these parts, by example in automotive construction.

For their fitting, we practice across the room tubular, perpendicular to the direction of elongation thereof, a hole able to wrap the overall outline of the cylindrical part, and, for example to the press, we jointly submit this cylindrical part and this part tubular to a relative movement which results in the cylindrical part engages under stress in the hole of the tubular part on one side thereof however the tubular part is butted outwardly from the side opposite to the previous one.

Various difficulties are to be overcome during such a fitting.

First, to avoid untimely deformation of the part tubular during the formation therein of the hole necessary for this fitting, it should normally be done by machining, at the cost of setting using relatively complex and expensive tools.

Then, this tubular piece forming, generally, around its hole, by the very fact of its tubular structure, two partitions, that of these partitions which, during the fitting of the cylindrical part, is located side of the engagement of this cylindrical piece cashes first of all the corresponding fitting force and is thus itself susceptible to be the object of some distortion.

If this is the case, the cross section of the tubular piece around of its hole is modified, which can be detrimental to the quality of the mechanical connection normally ensured between the cylindrical part and it, and, therefore, holding the whole.

In any event, the apparent deformation of the part tubular cannot fail to bring some discredit to this outfit, and the assembly concerned must therefore normally be discarded.

Furthermore, even in the absence of any deformation of one or the other of the partitions of the tubular part, the contact surface between this part tubular and the cylindrical part is reduced to that of the edge of the partitions of this tubular piece around its hole.

However, it is on this contact surface that the quality of the mechanical connection sought.

It turns out, in practice, that at least for some applications, in which the parts in question are subjected to a stress tearing and / or vibration, this contact surface can be insufficient to ensure the good performance of the assembly.

To overcome, at least in part, this last drawback, it was proposed in Swiss Patent No. 383,303 (see preambles to claims 1 and 10) to form a fallen edge around the hole of the tubular part, on at least one of the partitions of this part tubular, and, in practice, on both of them.

In practice, in this Swiss patent, the tools used for this make is a punch whose end is blunt in the shape of a blade, so that, during the formation of the fallen edge, the partition concerned is simply pushed back laterally, on either side of this blade.

It follows, on the one hand, that the fallen edge obtained does not extend over the entire perimeter of the hole it borders, and, secondly, that, height null at the two ends of a diameter of this hole, its height varies from one to the other of these ends, to the detriment of the homogeneity of the reinforcement obtained for holding the cylindrical part in the tubular part, and therefore definitive, at the expense of this reinforcement.

In addition, and above all, the risk of untimely deformation of one or other of the partitions of the tubular part during the fitting of the cylindrical part in the hole thereof remains almost unchanged.

The present invention generally relates to a provision to avoid such deformation and further leading to other advantages.

This object is achieved according to the invention first of all by a process for press fit of an at least locally cylindrical part, here said simply for convenience cylindrical part, in a tubular part, generally transverse to it, this process being of the kind according to which a hole envelops the overall contour of the cylindrical part having to cross right through the tubular part by affecting one and the other of the two partitions that this tubular piece forms overall transversely around it, we form, on at least a portion of the perimeter of this hole, for at least one of the partitions of the tubular part, a fallen edge which, integral with this partition, extends in the direction of the other bulkhead of the tubular part, and the cylindrical part is jointly submitted and the tubular part to a relative movement from which it follows that the cylindrical part engages under stress in the hole of the tubular part on one side thereof however that this tubular part is buttressed externally on the side opposite to the previous one, characterized in that, prior to the formation of the fallen edge on the tubular part, insert in this one a spacer wedge able to buttress it internally at vicinity of the hole on at least a portion of the perimeter thereof.

Thanks to this spacer wedge, any deformation is avoided for that partitions of the tubular part which would be susceptible to such deformation, that is to say for that of these partitions located on the side which is the engagement of the cylindrical part.

As a corollary, thanks to the fallen edge bordering the hole of the part tubular, the contact surface between this tubular part and the part cylindrical is significantly increased, to the benefit of holding the assembly, and, preferably, there is formed such an edge fallen on one and the other of the partitions of the tubular part, over the entire perimeter of the hole corresponding, and of substantially constant height all around it.

The fallen edge (s) thus used can be formed by stamping, the spacer wedge present inside the tubular part forming therein a matrix suitable for allowing such stamping, without deformation of the partition concerned.

According to the invention, it can if desired be advantageously drawn a additional part of this spacer block for the very formation of the hole initially required in it.

According to this possibility, the spacer wedge is placed in the tubular piece before the formation of this hole, and a hole is formed, in this case a pilot hole, in this tubular part by simple die cutting of it.

Unlike the tools to be used for machining, the tools to be used for such a die cut is advantageously very simple and inexpensive.

It also advantageously does not cause any chip problem, and it is hardly subject to wear.

Finally, this tool is advantageously likely to be used works on a standard machine, in this case a simple press, and, more particularly, on a simple hydraulic press, without any layout specific.

The result is, overall, a great saving in implementation and realization.

The present invention also relates to an assembly formed by two pieces fitted in a cross as defined in claim 10.

According to the invention, such an assembly is normally advantageously free from any deformation, the spacer spacer implementation effectively rebutted from the inside during engagement at least locally cylindrical part in the hole of the tubular part, that of the partitions of this tubular piece which is located on the side of this

la figure 1 est une vue en perspective d'un ensemble formé de deux pièces emmanchées en croix suivant l'invention ;

la figure 2 est, à échelle supérieure, une vue partielle en coupe longitudinale de cet ensemble, suivant le plan II-II de la figure 1 ;

la figure 3 est, à échelle différente, une vue en perspective de la cale entretoise mise en oeuvre dans cet ensemble, représentée isolément ;

les figures 4A, 4B, 4C, 4D, 4E et 4F sont des vues partielles en coupe longitudinale, qui, en correspondance avec celle de la figure 2, illustrent diverses phases successives de la réalisation de l'ensemble suivant l'invention ;

la figure 5 est une vue partielle en perspective d'un des poinçons mis en oeuvre pour cette réalisation ;

la figure 6 est une vue partielle en perspective d'un autre des poinçons également mis en oeuvre ;

la figure 7 est une vue partielle en coupe longitudinale, qui, en référence à celle de la figure 2, se rapporte à une variante de mise en oeuvre de l'invention.

The objects of the invention, their characteristics and their advantages will appear from the description which follows, by way of example, with reference to the appended schematic drawings in which:

Figure 1 is a perspective view of an assembly formed of two parts fitted in a cross according to the invention;

Figure 2 is, on a larger scale, a partial view in longitudinal section of this assembly, along the plane II-II of Figure 1;

Figure 3 is, on a different scale, a perspective view of the spacer block implemented in this assembly, shown in isolation;

FIGS. 4A, 4B, 4C, 4D, 4E and 4F are partial views in longitudinal section, which, in correspondence with that of FIG. 2, illustrate various successive phases of the production of the assembly according to the invention;

Figure 5 is a partial perspective view of one of the punches used for this embodiment;

Figure 6 is a partial perspective view of another of the punches also used;

Figure 7 is a partial view in longitudinal section, which, with reference to that of Figure 2, relates to an alternative embodiment of the invention.

As illustrated in these figures, it is, overall, the realization of an assembly 10, which, as is better visible in FIG. 1, is formed of two pieces fitted crosswise, namely a cylindrical piece 11 and a tubular part 12.

As stated above, the cylindrical part 11 is, in a way general, defined as being a part whose external surface 13 is at less locally, at its fitting with the tubular part 12, a cylindrical surface.

In the embodiment shown, the cross section of this outer surface 13 is assumed to have a circular contour and to be keep on going.

But it can just as easily have another outline and / or be more or less indented.

In the embodiment shown, the cylindrical part 11 is also assumed to be full, like a bar.

But it could just as easily be a hollow part, and by tubular example, like a socket, to serve as a housing for a any other component not shown.

The tubular part 12, meanwhile, has, overall, a direction of elongation D, towards which the generators of the surface outer 13 of the cylindrical part 11 extend substantially orthogonally.

This direction of elongation D is shown diagrammatically in lines interrupted in Figures 1, 2, 4A, 4B, 4C, 4D, 4E and 4F.

The length L1 of the tubular part 12 along its direction of elongation D may be greater or less.

In the embodiment shown, the tubular part 12 is, at As an example, a slender piece, insofar as this length L1 is relatively large, especially compared to its width L2.

The cross section of the tubular part 12 can be any.

In the embodiment shown, this cross section is, for example, largely flattened in a buttonhole, substantially perpendicular to the generatrices of the external surface 13 of the part cylindrical 11.

Furthermore, in this embodiment, this cross section is uniform over the entire length L1 of the tubular part 12.

But this is not necessarily so, the cross section of the tubular part 12 can on the contrary be more or less modulated according to its length L1.

It suffices that, at the level of the cylindrical part 11, it has a width L2 sufficient to receive it.

Finally, in the embodiment shown, the tubular part 12 is, for example, straight or substantially straight.

But it is not necessarily so either.

On the contrary, this tubular part 12 can just as easily be more or less consistent.

For example, it can be more or less curved or curved.

Anyway, the tubular part 12 has, overall transversely, and, more precisely, generally transversely by relative to its direction of elongation D, for the intervention of the part cylindrical 11, a hole 14, which envelops the overall contour of the part cylindrical 11, the cross member right through, and in which, according to arrangements described in more detail later, the cylindrical part 11 is forcibly engaged.

This hole 14 therefore affects either of the two partitions 15 that the tubular part 12 forms generally transversely around it, and, in the embodiment shown, it has a circular outline.

Let D1 be its diameter.

In the embodiment shown, the hole 14 intervenes, by way of example, at a distance from both ends of the tubular part 12.

But this is not necessarily so.

Finally, in the embodiment shown, and having regard to the flattening of the cross section of the tubular part 12, both partitions 15 of this tubular part 12 are substantially flat, at least at least near hole 14.

But it is not necessarily so either.

Let E be the internal thickness of the tubular part 12 at its hole 14, i.e. the distance internally separating one from another partitions 15 at the level of this hole 14.

Prior to the engagement of the cylindrical part 11 in the hole 14 of the tubular part 12, and according to methods described in more detail subsequently, on at least a portion of the perimeter of the hole 14, for at least one of the partitions 15 of the tubular part 12, a fallen edge 18, which, integral with this partition 15, extends in the direction of the other partition 15 of the tubular part 12, substantially perpendicular to this other partition 15.

According to the invention, prior to the formation of this fallen edge 18, a spacer block 16 is also inserted in the tubular part 12, also described in more detail later, capable of internally buttressing this tubular part 12 in the vicinity of hole 14.

Preferably, and this is the case in the form of setting shown work, a fallen edge 18 is formed over the entire perimeter of the hole 14.

Preferably, also, the spacer block 16 inserted in the tubular part 12 intervenes at least in the direction of elongation D of it.

In other words, it occurs at least in the middle zone of partitions 15 of the tubular part 12, on either side of the hole 14 of this tubular part 12.

In the embodiment shown, the spacer block 16 is circularly continuous and it therefore intervenes without discontinuity all around the hole 14.

In the general form of a ring, it has, in plan, a overall outline generally similar to that of hole 14, and, of diameter greater than that of the latter, it extends coaxially around it.

The spacer 16 may, for example, have in axial section, a profile in rectangle or square, and, in practice, this profile can be the most commonly used, this spacer block 16 can for example be formed by a section of tube, preferably metallic, machined or not.

But, in the embodiment shown, the spacer 16 has, in axial section, an isosceles trapezoid profile.

More specifically, the spacer block 16 comprises, overall, in this embodiment, in addition to the flats 19, which truncate it transversely at its axial ends while being sufficiently wide so that its compressive strength is not compromised, on the one hand, an inner surface 20, which is generally cylindrical, and, on the other hand, a outer surface 21, which has a middle portion 22 itself generally cylindrical, and, each arranged respectively on the one hand and on the other, axially, from this middle part 22, two facets overall tapered 23.

It is essentially the interior surface 20 which has, in plan, a overall contour, in this case circular, generally similar to that of the hole 14 of the tubular part 12.

Axially, the spacer block 16 used has preferably good compressive strength and good rigidity.

For example, it is made of metal or synthetic material tough.

According to the invention, a first advantage is taken of this spacer wedge 16 during your formation of the hole 14 of the tubular part 12.

Indeed, according to the invention, this spacer 16 being placed in place in the tubular part 12 before the formation of this hole 14, a pilot hole 14 ', in this tubular part 12, by simple die-cutting of it, Figures 4B and 4C.

A second advantage is then taken from the spacer 16, for the formation of the fallen edge 18.

According to the invention, this edge is preferably formed dropped 18 by stamping of the partition 15 concerned.

In both cases, that is to say both during the formation of the pilot hole 14 'that during the formation of the dropped edge 18, the spacer spacer 16 serves as a matrix for the relevant partition 15 of the tubular part 12.

Preferably, and this is the case in the form of setting represented work, a fallen edge 18 is formed on one and the other of partitions 15 of tubular part 12, on at least part of the perimeter of the hole 14, and, in practice, over the whole of it.

However, for the implementation of the invention, it can, by example, proceed as follows.

Firstly, in Figure 4A, the spacer block 16 is inserted in the tubular part 12, along arrow F1 of this FIG. 4A, being introduced into this tubular part 12 from one of the ends, from this, until it comes substantially to the right of the location provided for the hole 14 to be formed.

In practice, this insertion can advantageously be done without high precision, the spacer 16 coming from itself is centered by relative to this location when the hole 14 is formed.

Preferably, however, adequate maintenance is ensured of the spacer block 16 in the tubular part 12.

For example, from one of its flats 19 to another, the spacer 16 has a height H substantially equal to the internal thickness E of the tubular part 12, or even slightly greater than this thickness E, so that it is forcibly engaged between the two partitions 15 and that it is therefore duly stuck between them.

However, if desired, maintaining the spacer block 16 in position can be insured, or strengthened, by other means, and, for example, by means mechanical, such as fingerprints obtained by local stamping of the tubular part 12.

In a second step, FIGS. 4B to 4E, the training is carried out from hole 14 and that of the fallen edges 18.

The tools used for this purpose operate in practice on a standard machine, in this case a simple hydraulic press.

This tool 25 comprises, successively, bottom to top, a first stepped punch 26 having a first section 27, by the free end 28 from which it is able to cut a pilot hole 14 'to the cookie cutter, a second section 29, with progressive transverse profile, by which it is capable of ensuring a stamping, and a third section 30, by which it is able to perfect this stamping.

The diameter D2 of the first section 27 is much smaller than that D1 of the hole 14 to be formed, while the diameter D3 of the third section 30 is substantially equal to this diameter D1, while being slightly less than this.

Preferably, the free end 28 of the first section 27 of the punch 26 is circularly divided into at least two lips 31, the edges are connected in continuity with each other and thus form the thread or cutting edge of the whole.

In the embodiment shown, only two lips 31 are provided.

They form, internally, a dihedral 32, which is concave, and of which the edge extends substantially transversely relative to the axis of the punch 26.

The first section 27 of the punch 26 therefore generally has a inverted V configuration.

In the embodiment shown, the end of each of its lips 31 is cut transversely by a flat 33.

The tool 25 also includes, for buttressing the part tubular 12 to be worked, a matrix 34 hollowed out of a hole 35 whose diameter D4 is substantially equal to the diameter D2 of the first section 27 of the punch 26 while being slightly greater than this diameter D2.

Once the tubular part 12 has been applied, by one of its partitions 15, hereinafter called second partition 15, on the matrix 34, being duly held thereon by clamping means of the usual type, not shown, the punch 26, which extends directly above the hole 35 of the die 34, is controlled to move in the direction of the latter, along arrow F2 of Figure 4B.

By its first section 27, the punch 26 successively ensures, first of all, the cutting of the other partition 15 of the tubular part 12, called below first partition 15, FIG. 4B, with a slight inward folding from the edge 18 ′ thereof intended to form a fallen edge 18, then the cutting of the second partition 15, FIG. 4C.

As will be noted, thanks to the inverted V configuration of this first section 27, waste 36 from the first partition 15 of the tubular part 12 remains temporarily attached thereto, so that it is not not likely to interfere with the route of this first section 27 before this only attacks the second partition 15 of the tubular part 12, which avoids that it can inadvertently disturb the cutting of the latter.

After detaching from the first partition 15, the waste 36 is discharged through the hole 35 of the matrix 34, together with the waste 37 in from the second partition 15, FIG. 4C.

By its second section 29, the punch 26 completes the inward drawdown of the fallen edge 18 from the first partition 15, and, as shown in Figure 4C, this drawdown is then confirmed by the third section 30.

The tool 25 includes a second punch 38 capable of ensuring then successively a stamping and a calibration of the tubular part 12.

For the intervention of this second punch 38, and, as shown in Figures 4D and 4E, the tubular part 12 is placed on a new matrix 39 perforated with a hole 40 whose diameter D5 is substantially equal to that D1 of the hole 14 to be formed while being slightly greater than the latter.

Like the first punch 26, the second punch 38 is a floor punch.

In addition to a first section 41, generally frustoconical, and a second section 42, generally cylindrical, capable of ensuring the folding down from the fallen edge 18 coming from the second partition 15 of the room tubular 12, it presents, successively, from top to bottom, alternating with connecting sections 43, 43 ′ ... etc ..., at least one other section 44, 44 '... etc ..., generally cylindrical, with a diameter greater than that of second section 42, for a successive calibration, in several passes, of the hole 14 then obtained.

For example, and as shown, several sections are provided 44, 44 '... etc ..., whose respective diameters are increasing.

For its action, the second punch 38, which extends directly above the hole 40 of the matrix 39, is controlled to move in the direction of the latter, along arrow F3 of Figures 4D and 4E.

It then suffices, also for the press, to submit jointly the cylindrical part 11 and the tubular part 12 to a relative movement which it results that the cylindrical part 11 engages under stress in the hole 14 of the tubular part 12, along arrow F4 of FIG. 4F, by intervening, for do this, on a first side of this tubular part 12, while buttressing externally this tubular part 12, on the side opposite to the previous one, by a die 45 perforated with a hole 46 whose diameter D6 is slightly greater than that D1 of the hole 14 of the tubular part 12.

Preferably, the developed fitting effort is controlled by strain gauges.

As will be noted, it is not implemented, only one and the same punch, in this case the first punch 26, for the Cut out a pilot hole 14 'in the tubular part 12 and for stamping one of the partitions 15 thereof.

It goes without saying, however, that, if desired, these two operations can also be secured by different punches.

In any event, it follows from the above that the set 10 according to the invention comprises, between the two partitions 15 that its tubular part 12 forms around its hole 14, a spacer 16 which, in a manner general, extends over at least a portion of the perimeter of this hole 14, and that, for at least one of the partitions 15, this hole 14 is located, in a way general, bordered, on at least a portion of its perimeter, by a fallen edge 18, which, integral with this partition 15, extends in the direction of the other partition 15 of the tubular part 12, substantially perpendicular thereto.

In the embodiments shown, the fallen edge 18 extends over the entire perimeter of the hole 14 of the tubular part 12, of a integral with the partition 15 concerned thereof, and there is thus an edge fallen 18 for both of the partitions 15 of this tubular part 12.

In addition, this fallen edge 18a, from the inner surface of the partitions 15, a constant height h, all around the hole 14.

As will be noted, this hole 14 is defined by the edges fallen 18 from the partitions 15, and, more precisely, by the external, free surface, of these fallen edges 18.

Thus formed by these fallen edges 18, the contact surface by which the cylindrical piece 11 and the tubular piece 12 are engaged one with the other is therefore significantly higher than that of the only tranches of partitions 15 of this tubular part 12.

In the embodiment shown in Figures 1 to 6, the fallen edges 18 extend as close as possible to the spacer 16, being substantially in contact with it.

Preferably, even, they rest radially on the wedge spacer 16.

In the embodiment shown in Figures 1 to 6, the free edges of the fallen edges 18 extend at a distance from each other, the height h of these fallen edges 18, which is the same for both of them them, being less than half the height H of the spacer 16.

But this is not necessarily so.

For example, in Figure 7, the free edges of the fallen edges 18 can at least locally be from place to place in contact with one another, to strengthen the resistance to sinking when engaging the part cylindrical 11, parallel to the action also exerted in this regard by the spacer 16.

In all cases, it is desired, for the spacer block 16, a maximum compressive strength, both axially and radially.

The present invention is moreover not limited to the forms of placing described and represented, but includes all variant, without departing from the scope of the invention such as defined in the claims.

Claims (19)

1. A method for force fitting an at least locally cylindrical part (11), here for convenience simply designated cylindrical part, into a tubular part (12), generally transversely in relation thereto, of the type according to which a hole (14) envelopes the overall contour of the cylindrical part (11) before passing right through the tubular part (12) thereby both taking the shape of two partitions (15) which this tubular part (12) generally forms transversely around it, there is formed on at least one portion of the perimeter of said hole (14), for at least one of the partitions (15) of the tubular part (12), a flanged edge (18) which, integral with this partition (15), extends towards the other partition (15) of the tubular part (12), and the cylindrical part (11) and the tubular part (12) are jointly subjected to a relative movement as a result of which the cylindrical part (11) engages under pressure in the hole (14) of the tubular part (12) on one side thereof while this tubular part (12) abuts externally against the side opposite the former, characterised in that, prior to the formation of the flanged edge (18) on the tubular part (12), there is inserted into the latter a cross-piece wedge (16) which is adapted to abut internally in the vicinity of the hole (14) against at least one portion of the perimeter of the latter.
2. A method according to claim 1, characterised in that the flanged edge (18) is formed by stamping the relevant partition (15) of the tubular part (12).
3. A method according to either claim 1 or claim 2, characterised in that, the cross-piece wedge (16) having been fitted into the tubular part (12) prior to the formation of the hole (14) therein, a pilot hole (14') is formed in said tubular part (12) by simply punching it out therefrom with a punch.
4. A method according to claims 2, 3, taken together, characterised in that only a single punch (26) is used for punching out a pilot hole (14') in the tubular part (12) and for stamping one of the partitions (15) thereof.
5. A method according to any one of claims 1 to 4, characterised in that the cross-piece wedge (16) is introduced into the tubular part (12) starting from one end of the latter.
6. A method according to any one of claims 1 to 5, characterised in that a flanged edge (18) is formed over the entire perimeter of the hole (14).
7. A method according to any one of claims 1 to 6, characterised in that a flanged edge (18) is formed on both of the partitions (15) of the tubular part (12).
8. A method according to either claim 6 or claim 7, characterised in that only a single and even second stepped punch (38) is used, which is adapted to ensure successively punching and calibration to form the flanged edge (18).
9. A method according claim 8, characterised in that the punch (38) has a first generally frustoconical portion (41), a second generally cylindrical portion (42) and, alternating with connecting portions (43,43'...etc.), at least another generally cylindrical portion (44,44'...etc.) of a diameter which is greater than that of the second portion (42) for successive calibration, in several passes, of the hole (14) thus obtained.
10. An assembly formed by two cross forced-fitted parts (11,12), namely an at least locally cylindrical part (11), here for convenience simply designated cylindrical part, and a tubular part (12) having a hole (14) into which the cylindrical part (11) is force fitted, said hole (14) being bounded, over at least one portion of its perimeter and for at least one of the partitions (15) which the tubular part (12) forms about it, by a flanged edge (18) which, integral with said partition (15), extends towards the other partition (15) of the tubular part (12), characterised in that it comprises between the two partitions (15) of the tubular part (12) a cross-piece wedge (16) which extends at least over a portion of the perimeter of the hole (14).
11. An assembly according to claim 10, characterised in that the flanged edge (18) extends over the entire perimeter of the hole (14) in the tubular part (12).
12. An assembly according to either claim 10 or claim 11, the flanged edge (18) is of a substantially constant height (h) all around the hole (14).
13. An assembly according to any one of claims 10 to 12, characterised in that the flanged edge (18) is continuous with the relevant partition (15) of the tubular part (12).
14. An assembly according to any one of claims 10 to 13, characterised in that the flanged edge (18) extends close to the cross-piece wedge (16).
15. An assembly according to any one of claims 10 to 14, characterised in that it comprises a flanged edge (18) for both of the partitions (15) of the tubular part (12).
16. An assembly according to any one of claim 15, characterised in that the free edges of the two flanged edges (18) extend at a distance from one another.
17. An assembly according to any one of claims 10 to 16, characterised in that the cross-piece wedge (16) acts at least in the direction of extension (D) of the tubular part (12).
18. An assembly according to any one of claims 10 to 17, characterised in that the cross-piece wedge (16) is circularly continuous.
19. An assembly according to any one of claims 10 to 18, characterised in that the inner surface (20) of the cross-piece wedge (16) has, in plan, an overall contour which is generally similar to that of the hole (14) in the tubular part (12).

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