WO1999020415A1

WO1999020415A1 - Roll bending machine for forming a ring-shaped part

Info

Publication number: WO1999020415A1
Application number: PCT/FR1998/002241
Authority: WO
Inventors: Charles Marcon; Jean-Paul Lespour
Original assignee: Escofier Technologie S.A.
Priority date: 1997-10-22
Filing date: 1998-10-20
Publication date: 1999-04-29
Also published as: FR2769859A1; ES2173631T3; DE69805200D1; EP1024914A1; FR2769859B1; DE69805200T2; EP1024914B1

Abstract

The invention concerns a roll bending machine which, for rolling a ring-shaped part (10), comprises a forming mandrel (16), a forming wheel (16), a roll bending shell (19) corresponding to the final form required for the ring-shaped part (10) transverse cross-section, and two support rollers (20) pressing on the forming mandrel (16) on either side of the roll bending shell (19). The invention is characterised in that two surface-control rollers (29) are further provided for acting respectively on the ring-shaped part (10) lateral surfaces (13) at a distance from the roll bending shell (19), said surface-control rollers (29) are arranged between the supporting rollers (20), in the overall volume enclosing the external outline thereof. The invention is, for example, useful for forming a ball raceway or a ball homokinetic transmission cage.

Description

"Rolling machine for annular part to be formed"

The present invention relates generally to the rolling of an annular part for the purpose of forming the latter by rolling, which, in practice, is cold rolling.

It relates more particularly, but not necessarily exclusively, to the case where the annular part to be formed is, for example, a ring for ball bearings, or a ball retaining cage for constant velocity transmission with balls. For the rolling of such an annular part, it is known to use a machine comprising, on the one hand, various rotary members, namely, a forming mandrel, which is rotatably mounted around a first axis, and on which the annular part to be formed, or, more precisely a blank thereof, must be engaged with play, a forming wheel, which is rotatably mounted around a second axis parallel to the first, and which is capable of defining , with the forming mandrel, a rolling envelope corresponding to the final shape sought for the cross section of this annular part, and two support rollers, which, coaxial with each other, without necessarily being carried by the same shaft, are rotatably mounted around a third axis parallel to the previous two and located in the same plane as these, and which are supported on the forming mandrel on either side of the envelope rolling to absorb the reaction to the ef strong rolling radial provided by the forming wheel, and, on the other hand, drive means specific to the rotary drive of at least one of these rotary members. Such a rolling machine is notably described, succinctly, in American patent No Re 26,594.

For certain applications, at least, it is requested that, on leaving such a rolling machine, the worked annular part can be considered as constituting a finished part, that is to say a part which does not require reworking. subsequent machining, except for a any heat treatment and any necessary rectification after it.

However, the parting plane inevitably intervening between the forming wheel and the forming mandrel necessarily leaves traces on the lateral faces of the annular workpiece.

It has therefore been envisaged, as has already been the case in other fields, for example for the hot manufacture of mechanical rings of large diameter, to make use of these lateral faces, at a distance from the rolling envelope, two face control rollers, one roller per side face to be checked, for surfacing these faces.

The term “face control rollers” is understood to mean rollers which are intended to control a form of annular part already produced.

Such rollers have a completely different function from that of axial forming rollers such as those described in US Pat. No. 3,681,962, in particular in FIGS. 4 to 8 of this document.

In these figures, the forming wheel and the forming mandrel do not define between them a rolling envelope, so that the axial deformation of the material is free between these two tools.

It is then necessary to provide axial forming rollers, at a distance from the forming zone between the wheel and the mandrel, in order to obtain an annular part of desired width.

US-A-3,681,962 does not, moreover, provide for such axial forming rollers in its variants of machines which form the material in a rolling envelope. But, to return to the rolling machines comprising face control rollers, there then arises, in particular, the problem of the installation of these face control rollers, even though, depending on this installation, the conditions d 'intervention of these face control rollers, and therefore their efficiency, that the overall size. The present invention generally relates to a provision which, from this double point of view, is particularly satisfactory.

More specifically, it relates to a rolling machine for annular part to be formed, of the kind comprising, on the one hand, various rotary members, namely, a forming mandrel, which is rotatably mounted about a first axis , a forming wheel, which is rotatably mounted around a second axis parallel to the first, and which is capable of defining, with the forming mandrel, a rolling envelope corresponding to the final shape sought for the cross section of the part annular concerned, and two support rollers, which, rotatably mounted around a third axis parallel to the previous two and located in the same plane as these, are supported on the forming mandrel on either side of the rolling envelope, and, on the other hand, drive means specific to driving in rotation of at least one of these rotary members, this rolling machine being generally characterized in that , two control rollers face being further provided each to intervene respectively on the lateral faces of the annular part at a distance from the rolling envelope, these face control rollers are arranged between the support rollers, in the overall volume enveloping the outer contour of these.

It follows, first of all, that, without the slightest overhang, these two face control rollers can advantageously be held at one and the other of their ends, for the benefit of their efficiency.

It also results therefrom that they do not in any way burden the bulk of the assembly.

Preferably, the axes of the face control rollers extend in the same plane as that, hereinafter said for the sake of convenience, rolling plane, in which the axes of the forming mandrel, of the forming wheel also extend. , and support rollers. Thus, the work of the rolling machine according to the invention is done under conditions of symmetry and stability advantageously favorable to the desired face control.

Preferably, also, the rolling machine according to the invention comprises follower rollers, which, rotatably mounted, frame the rolling envelope for the maintenance, in the rolling plane, of the axis of the annular workpiece.

Thus, the work of this annular part is advantageously done in a perfectly regular manner, for the benefit, again, of the desired face control.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which: FIG. 1 is a perspective view of the initial blank of a simplified form of an annular part likely to be concerned, before the forming thereof; Figure 2 is an axial sectional view of this blank, along line 11-11 of Figure 1; Figures 3 and 4 are views, which each similar to those of Figures 1 and 2, respectively, relate to the simplified shape of the annular part concerned, after the forming thereof; FIG. 4A is, on a different scale, a partial view in axial section, which, corresponding in part to that of FIG. 4, relates to a more constructive annular part, for a first type of defect thereof in its plane seal; Figure 4A 'is a partial view in axial section similar to that of Figure 4A, for a second type of defect in the annular part concerned; FIG. 4B is a partial view in axial section similar to that of FIGS. 4A, 4A ', after correction of the defect by means of the face control according to the invention; Figure 5 is, with local cutaway, a perspective view in principle of the rolling machine according to the invention; Figure 6 is, after elimination of one of the support rollers it comprises, a more constructive perspective view of this rolling machine; Figure 7 is a different scale, a partial view in cross section along the line VII-VII of Figure 6; Figure 8 is a larger scale, a partial view in axial section along the line VIII-VIII of Figure 6; Figure 9 is another partial sectional view along the line IX-IX of Figure 6; Figure 10 is, along the arrow X of Figure 6, a schematic principle view of the structure to which belong the support arms that includes this rolling machine; Figure 1 1 is a schematic view which, similar to that of Figure 10, relates to a first embodiment; Figure 1 2 is a schematic view which, also similar to that of Figure 10, relates to a second alternative embodiment; Figure 1 3 is a partial elevational view of this alternative embodiment, along arrow XIII of Figure 1 2; Figure 1 4 is, on a larger scale, a partial sectional view along the line XIV-XIV of Figure 1 3.

As illustrated in these figures, it is, overall, to ensure, by rolling, the rolling of an annular piece 1 0 from a blank 1 0 '.

For example, and as shown, the annular part 1 0 is intended to form the outer ring of a ball bearing. It comprises, overall, along a substantially rectangular overall cross section, an external face 1 1, an internal face 1 2, and two lateral faces 1 3, with, annularly, recessed on the internal face 1 2, in the median zone thereof, a groove 14, of circular cross section.

In the simplified embodiment shown in Figure 3, the outer face 1 1 and the side faces 1 3 are straight, and, with the exception of the groove 1 4, it is the same for the inner face 1 2.

In practice, and by reason of the forming process used to produce the groove 14, as described below, the lateral faces 1 3 of the annular part 1 0 are not flat, but on the contrary comprise , in clearance, two frustoconical sections which join one another along a joint plane T, FIGS. 4A, 4A '.

In this joint plane T there may be surface irregularities by excess, FIG. 4A, in the form of burrs or other projections, or by default, FIG. 4A ', in the form of cracks or other depressions.

The invention proposes, by a face check, the elimination of these surface irregularities.

In practice, it leads to the formation, in the joint plane T, of a regular flat, as shown in FIG. 4B.

Anyway, the initial blank 10 'is, for example, and as shown, a simple section of tube, the internal face 1 2' is smooth.

It is therefore a question of forming the groove 14 on this internal face 1 2 '.

The rolling used for this purpose is done, in practice, according to methods described in more detail later, on a rolling machine 1 5, and it is necessarily accompanied by an increase in the diameter of the annular part 1 0 worked.

The rolling machine 1 5 according to the invention will not be described in all its details here. In particular, there will be no mention here of its frame, it being the responsibility of the skilled person.

This frame has also not been shown in the figures.

In practice, only the elements of the rolling machine 1 5 according to the invention which are necessary for understanding the invention will be described here.

In a manner known per se, and as shown diagrammatically in broken lines in FIG. 4 and in solid lines in FIG. 5, the rolling machine 1 5 according to the invention generally comprises, on the one hand, various rotary members 1 6 , 1 8, 20, namely, a forming mandrel 1 6, which is rotatably mounted around a first axis A _{1 f} and on which the annular part 10 to be formed, or, more precisely, the blank 1 0 ' of it, must be engaged with play, a forming wheel1 8, which is rotatably mounted around a second axis A ₂ parallel to the first, and which is capable of defining, with the forming mandrel 1 6, an envelope of rolling 1 9, corresponding to the final shape sought for the cross section of this annular part 10, and two support rollers 20, which, rotatably mounted around a third axis A ₃ parallel to the previous two and located in the same plane P that these, here said for the sake of convenience, rolling plane, rest on the mandrel d e forming 1 6 on either side of the rolling envelope 1 9, and, on the other hand, drive means E suitable for driving in rotation of at least one of these rotary members 1 6, 1 8, 20.

In practice, the forming mandrel 1 6 comprises, on the one hand, a median section 21, which is of reduced cross section, and on which protrudes annularly a duly profiled rib 22 for forming the groove 14, and, d on the other hand, two lateral sections 23, which are of larger cross section and on which the support rollers 20 bear.

The forming wheel 1 8 itself comprises a median section 24, which is of reduced cross section, and two lateral sections 25, which are of larger cross section, to contain the axial creep of the annular part 10. As shown in Figure 5, the rolling machine 1 5 according to the invention also comprises, on either side of the forming mandrel 1 6, two follower rollers 26, which, rotatably mounted about axes A ₅ , surround the rolling envelope 1 9. These follower rollers 26 operate on the external face 1 1 of the annular part 1 0, to control the roundness and the symmetry and to take up possible deformations, and it follows that, during forming, the axis A ₄ of this annular part 1 0 remains in the rolling plane P of the axes A-,,, A ₂ ,

A ₃ - The axes A ₅ of the follower rollers 26 are therefore away from this rolling plane P, on either side of it.

These axes A ₅ are substantially parallel to the axes A-,, A ₂ , A _{3 above} , but one of them, at least, can however be advantageously slightly inclined with respect to these, to compensate for possible defects of external taper.

Preferably, the follower rollers 26 are arranged in a perfectly symmetrical manner with respect to the rolling plane P, while being for this purpose duly maintained by support means, known in themselves and not shown. They thus make it possible to maintain in the rolling plane P the axis A ₄ of the annular part 1 0.

The drive means E, which have only been shown diagrammatically in broken lines in FIG. 5, are also of known type.

In practice, these are motorization means using any motor.

As shown diagrammatically in FIG. 5, the drive means E are applied to the forming wheel 18 and to the support rollers 20.

But any other drive configuration is possible, and in any event, the forming mandrel 1 6, the forming wheel 1 8, the support rollers 20 and the follower rollers 26 obviously rotate in synchronism.

The rolling machine 1 5 according to the invention finally comprises a feeler 27 for checking the diameter of the annular part 10. This feeler 27 intervenes between the support rollers 20.

According to the invention, two face control rollers 29 being further provided each to intervene respectively on the side faces 1 3 of the annular part 1 0 at a distance from the rolling envelope 1 9, as shown diagrammatically in the figure 5, these face control rollers 29 are arranged between the support rollers 20, in the overall volume enveloping the outer contour thereof.

Preferably, and this is the case in the embodiments shown, the axes A ₆ of the face control rollers 29 extend in the same plane as that in which the axes A ^ of the forming mandrel 1 also extend. 6, A ₂ of the forming wheel 1 8, and A ₃ of the support rollers 20, that is to say in the rolling plane P.

It follows from the above that the face control rollers 29 intervene by their generatrices on the side faces 1 3 of the annular part 1 0, and that they extend substantially radially with respect thereto.

Extending, in practice, on either side of the worked cross section of the annular part 10, they have a relatively large length I, which allows them, on the one hand, to be satisfied with the increase in diameter of the annular part 1 0 during its forming, and, on the other hand, to advantageously be suitable for annular parts 10 of different diameters.

In the embodiment more particularly shown in Figures 1 to 10, the face control rollers 29 are cylindrical, and, at least at the end of work, their axes A ₆ are parallel to each other. Preferably, and as shown, their diameter d is less than their length I.

For example, this diameter d is less than at least half of the length I. In the embodiment shown in Figures 1 to 1 0, it is substantially equal to one third of this length I.

More generally, the diameter d of the face control rollers 29 is preferably chosen to be as small as possible so that these face control rollers 29 are as penetrating as possible under low effort. Preferably, and this is the case in the embodiments shown, the face control rollers 29 are each respectively at least partially arranged inside the support rollers 20, each of these support rollers 20 comprising , recessed, on its internal face 30, and recessed with respect to its periphery 31, a recess 32 in which the corresponding face control roller 29 is at least partially engaged.

Thus, the support rollers 20 can rest on the forming mandrel 1 6 as close as possible to the rolling envelope 1 9, which allows effective support of this forming mandrel 1 6 by these supporting rollers 20 and therefore limits its bending. For example, and as shown, the recess 32 which each of the support rollers 20 thus comprises extends circularly all around its axis A ₃ .

Each of the support rollers 20 thus comprises a flange 20a, which, at its periphery 31, has annularly, projecting towards the other, a flange 20b, and which, in its central zone, has, axially, projecting in the opposite direction to the previous one, a thick part 20c forming a hub.

In practice, the face control rollers 29 are free to rotate.

In the embodiments shown, each of these face control rollers 29 is rotatably mounted on a support arm 34 mounted pivoting about a main pivot axis A ₇ orthogonal to the axis A ₃ of the support rollers 20.

Preferably, and this is the case in these embodiments, each of the support arms 34 which thus comprises the rolling machine 1 5 according to the invention extends generally diametrically relative to the support rollers 20 and has a central recess 35, of circular outline, for the passage, in particular, of the support shaft 36 of these support rollers 20.

This support shaft 36 has been shown diagrammatically in broken lines in FIG. 8. Preferably also, and this is also the case in the embodiments shown, the main pivot axis A ₇ of each of the support arms 34 intersects the axis A ₃ of the support rollers 20, as shown diagrammatically in broken lines in FIG. 7.

Overall, the two support arms 34, which are of similar configuration, are each in the form of a flange, with an annular median part 37, around their central recess 35, and, in diametrically opposite positions, one by relative to each other, two radial extensions

38 by means of one of which intervenes the corresponding face control roller 29. At their main pivot axis A ₇ , the support arms 34 are connected to each other, in an articulated manner, by at least one flange 39, here called for simple convenience central flange.

In the embodiments shown, two central flanges

39 are provided, which, parallel to each other, each extend respectively in diametrically opposite positions relative to each other and both intersect the main pivot axis A ₇ of each of the support arms 34.

In the embodiments shown, the main pivot axis A ₇ of each of the support arms 34 is materialized by two pins 40, which are directed, radially, towards the axis A ₃ of the support rollers 20, and which, directly or indirectly, bear radially in diametrically opposite positions with respect to each other, on a sleeve 41 centered on the axis A ₃ of the support rollers 20.

For example, and as shown, this sleeve 41 is in two parts, namely, an internal part 41 A, which, engaged on the support shaft

36 of the support rollers 20, and therefore integral in rotation with the latter, is in axial contact with the corresponding support roller 20, and an external part 41 B, which, forming a bearing, surrounds the internal part 41 A, with the interposition of rolling means 42, and on which the pins 40 bear. Anyway, there is, annularly, a radial clearance J between the support arms 34 and the sleeve 41 which they surround, and, more precisely, between the central recess 35 of these support arms 34 and the external part 41 B of this sleeve 41.

In the embodiments shown, the pins 40 bear on the sleeve 41 by means of bearings 43, FIG. 7, and, for the support of these, the external part 41 B of this sleeve 41 has, in positions diametrically opposite to each other, two flats 44.

The embodiment more particularly shown in FIGS. 1 to 1 0 relates to the case where the face control to be carried out must take place in a symmetrical and balanced manner on both of the side faces 1 3 of the annular part 10 , none of these lateral faces 1 3 can be taken as the reference face for the assembly.

In this case, the support arms 34 constitute, with the central flanges 39 which connect them, a structure in the form of a clamp, and, at their end opposite to the face control rollers 29, they are jointly subjected to a device for spacing 45.

In practice, this spacing device 45 intervenes between the support arms 34, and, more precisely, between the corresponding radial extensions 38 thereof. In the embodiment shown, this spacer device

45 implements a wedge 46, which, under the control of a control device 47, and as shown diagrammatically by the double arrow F-, in FIG. 7, is mounted movable in a plane perpendicular to the axis A ₃ support rollers 20, and therefore perpendicular to the rolling plane P, preferably micrometrically.

More specifically, in the embodiment shown, the corner

46 intervenes between two blocks 48, the opposite surface of which is semi-cylindrical, with generators parallel to the main pivot axis A ₇ of the support arms 34, and on which these support arms 34 are each articulated respectively.

Two return springs 49, which bear on the same tie rod

50 passing right through the support arms 34, permanently maintain elastically these support arms 34 in contact with the blocks 48, FIG. 8.

Preferably, and this is the case in the embodiments shown, the two support arms 34 are also jointly coupled to an anchoring device 52 capable of blocking them in rotation relative to the axis A ₃ of the rollers of support 20, FIG. 7. Finally, in the embodiment more particularly shown in FIGS. 1 to 10, each of the face control rollers 29 is directly rotatably mounted on its support arm 34.

More specifically, in this embodiment, each of the face control rollers 29 extends in a recess 53 of its support arm 34 which passes right through it.

More precisely, again, this recess 53 affects, in the manner of a slot, the corresponding radial extension 38 of this support arm 34, and, at the end of this radial extension 38, it is closed by a flange of centering 55. Thus, the shaft 56 of such a face control roller 29 can be advantageously supported at one and the other of its ends, as shown diagrammatically in broken lines in FIG. 7, and as shown in solid lines in FIG. 8. Preferably, stop means are moreover provided for ensuring a rotation stop of the support arms 34 of the face control rollers 29 relative to their axis A ₃ , and thus allowing the axes A _{6 to be} maintained. face control rollers 29 in the rolling plane P.

Reporting to the skilled person, these stop means have not been shown, and they will not be described here.

In practice, these abutment means result from the very implementation of the control device 47 and therefore belong to it.

In service, the face control rollers 29 are only actuated in a timely manner during forming, depending on the diameter of the annular part 1 0 to be worked.

To do this, the wedge 46 is then pressed between the extensions 38 of the support arms 34 opposite the face control rollers 29.

This results in a relative spacing, at this level, of these support arms 34, according to the double arrow F ₂ of FIG. 10, and, therefore, according to arrows F ₃ of this FIG. 10, a pivoting of these support arms 34 around their main pivot axis A ₇ which leads the face control rollers 29 which they carry to approach each other.

In view of the significant efforts then developed, the bending of the support arms 34 is most often sufficient to compensate for the inclination which is then theirs.

If desired, this inclination can also be compensated for by using conical face control rollers 29, as shown diagrammatically in FIG. 11. In this figure 1 1, the taper of these face control rollers 29 has been deliberately exaggerated, to make it visible and to facilitate understanding.

Anyway, the central flanges 39 connecting to one another the two support arms 34 advantageously serve to resume at this level the radial rolling reactions and thus advantageously relieve the rolling means 42 internal to the sleeve 41 .

Consequently, these rolling means 42 only support tangential rolling reactions, which themselves remain weak. Because the axes A ₆ of the face control rollers 29 extend in the rolling plane P, they permanently intersect the axis A ₄ of the annular part 1 0 during forming, despite the change in diameter of the latter, which, as a corollary with the action of the follower rollers 26, is advantageously a guarantee of maintaining the circular configuration of this annular part 10.

Although akin to surface rolling, the face control provided according to the invention does not in practice cause any appreciable creep of material.

The embodiment more particularly shown in FIGS. 1 2 to 14 relates to the case where, the face check to be carried out having to take place asymmetrically on the lateral faces 1 3 of the annular part 10, it is possible to choose one of these lateral faces 1 3 as a reference face for the assembly.

In this case, and as shown diagrammatically in FIG. 12, the support arms 34 are connected to each other, at a distance from their main pivot axis A ₇ , and in an articulated manner, each along an axis. secondary pivot A ' ₇ parallel to the main pivot axis A _{7 above} , by at least one flange 57, hereinafter called for simple convenience end flange, which is parallel to the central flanges 39, and which is likewise length than these. For example, only such an end flange 57 is provided.

Anyway, it acts on the support arms 34 on the side of the central flanges 39 opposite the face control rollers 29.

Anyway, also, the support arms 34 then constitute, with the flanges 39 and 57 which connect them, a structure in the form of a deformable parallelogram, and, as shown diagrammatically by a double arrow F ₄ in the figure. 1 2, the assembly is subjected to a control device 58 capable of allowing its position control with respect to the annular part 1 0 to be worked, by rotation about the pivot axes A ₇ , A ' ₇ , which, one of the support arms 34 being for example taken as a reference, makes it possible to work preferentially one of the lateral faces 1 3 of this annular part 10 rather than the other of these.

In the embodiment shown, FIG. 14, each of the face control rollers 29 is rotatably mounted on its support arm 34 by means of a roller support 59 pivotally mounted on this support arm 34 around a tilting axis A ₈ , which, parallel to that A ₆ of this face control roller 29, extends at a distance therefrom.

In addition, in this embodiment, the roller support 59 is subjected to two jacks 60, 61, which each extend respectively on either side of its pivot axis A ₈ , and which bear on the arm support 34.

Preferably, and this is the case in the embodiment shown, these jacks 60, 61 are integrated into this support arm 34.

For the rest, the provisions are of the same type as the previous ones.

In service, the relative approximation of the face control rollers 29 can be ensured by acting accordingly on the control device 58 and / or on the jacks 60, 61.

Different pressures in each of the cylinders 60 make it possible to obtain, for one of the face control rollers 29, a pressure level higher than that of the other, and thereby respect the asymmetry relationship to be satisfied.

Of course, the present invention is not limited to the embodiments described and shown, but encompasses any variant and / or combination of their various elements.

In particular, instead of being made perpendicular to the axis of the annular workpiece, the surface rolling of the lateral faces of the latter can be done at an angle to this axis, whatever the nature, cylindrical or conical , face control rollers used. In addition, instead of being cylindrical or conical, these face control rollers may possibly have a scalable outer surface if desired.

Furthermore, if the present invention has been more particularly described with reference to the outer ring of a bearing, it goes without saying that it applies equally well to the inner ring of such a bearing.

It is, in this case, the outer face of this ring which has a groove, and the forming wheel and the forming mandrel in turn have inverted conjugate shapes.

Claims

CLAIMS 1. Rolling machine for an annular part to be formed, of the type comprising, on the one hand, various rotary members (1 6, 1 8, 20), namely, a forming mandrel (1 6), which is rotatably mounted around a first axis (A-,), a forming wheel (1 8), which is rotatably mounted around a second axis (A ₂ ) parallel to the first, and which is capable of defining, with the forming mandrel (1 6), a rolling envelope (1 9) corresponding to the final shape sought for the cross section of the annular part (10) concerned, and two support rollers (20), which, rotatably mounted about a third axis (A ₃ ) parallel to the two preceding ones and situated in the same plane (P) as these, hereinafter called the rolling plane, rest on the forming mandrel (1 6) on either side of the rolling envelope (1 9) and, on the other hand, drive means (E) suitable for driving in rotation one at least of the rotary members (1 6, 1 8, 20), characterized in that, from ux face control rollers (29) being further provided to each intervene respectively on the lateral faces (1 3) of the annular piece (10) at a distance from the rolling envelope (1 9), these control rollers face (29) are arranged between the support rollers (20), in the overall volume enveloping the outer contour thereof.

2. Rolling machine according to claim 1, characterized in that it comprises two follower rollers (26), which, rotatably mounted, frame the rolling envelope (1 9) and operate on the external face (1 1) of the annular part (1 0).

3. Rolling machine according to claim 2, characterized in that the follower rollers (26) are arranged symmetrically with respect to the rolling plane (P).

4. Rolling machine according to any one of claims 2, 3, characterized in that the axes (A ₅ ) of the follower rollers (26) are substantially parallel to the axes (A _u A ₂ , A ₃ ) above, the at least one of them, however, being able to be slightly inclined with respect to these.

5. Rolling machine according to any one of claims 1 to 4, characterized in that the axes (A ₆ ) of the face control rollers (29) extend in the rolling plane (P).

6. Rolling machine according to any one of claims 1 to 5, characterized in that the face control rollers (29) are cylindrical and their axes (A ₆ ) are parallel to each other.

7. Rolling machine according to claim 6, characterized in that the diameter (d) of the face control rollers (29) is less than their length (I).

8. Rolling machine according to claim 7, characterized in that the diameter (d) of the face control rollers (29) is less than at least half of their length (I).

9. Rolling machine according to any one of claims 1 to 5, characterized in that the face control rollers (29) are conical.

10. Rolling machine according to any one of claims 1 to 9, characterized in that the face control rollers (29) are each respectively at least partially arranged inside the support rollers (20) , each of these support rollers (20) comprising, recessed, on its internal surface (30), and recessed with respect to its periphery (31), a recess (32) in which the face control roller ( 29) correspondent is at least partially engaged.

1 1. Rolling machine according to claim 10, characterized in that the recess (32) that each of the support rollers (20) comprises extends circularly all around its axis (A ₃ ).

1 2. Rolling machine according to any one of claims 1 to 1 1, characterized in that the face control rollers (29) are free to rotate.

1 3. Rolling machine according to any one of claims 1 to 1 2, characterized in that each of the face control rollers (29) is rotatably mounted on a support arm (34) around a main pivot axis (A ₇ ) orthogonal to the axis (A ₃ ) of the support rollers (20).

1 4. Rolling machine according to claim 1 3, characterized in that each of the support arms (34) which it comprises extends generally diametrically relative to the support rollers (20) and has a central recess (35 ) for the passage of the support shaft (36) of these support rollers (20).

1 5. Rolling machine according to claim 14, characterized in that the main pivot axis (A ₇ ) of each of the support arms (34) intersects the axis (A ₃ ) of the support rollers (20) .

1 6. Rolling machine according to claim 1 5, characterized in that, at their main pivot axis (A ₇ ), the support arms (34) are connected to each other, in an articulated manner , by at least one flange (39), here called central flange.

1 7. Rolling machine according to any one of claims

1 5, 1 6, characterized in that the main pivot axis (A ₇ ) of each of the support arms (34) is materialized by two pins (40), which, directly or indirectly, bear radially, in diametrically opposite positions relative to each other, on a sleeve (41) centered on the axis (A ₃ ) of the support rollers (20).

1 8. Rolling machine according to claim 1 7, characterized in that there is annularly a radial clearance (J) between the support arms (34) and the sleeve (41).

1 9. Rolling machine according to any one of claims 1 6 to 1 8, characterized in that, at their end opposite to the face control rollers (29), the support arms (34) are jointly subjected to a spacer (45), and they constitute, with the central flange or flanges (39) which connect them, a structure in the form of a clamp.

20. Rolling machine according to claim 1 9, characterized in that the spacer device (45) intervenes between the support arms (34) and implements a wedge (46) mounted movable in a plane perpendicular to the axis (A ₃ ) of the support rollers (20).

21. Rolling machine according to any one of Claims 1 6 to 1 8, characterized in that, at a distance from their main pivot axis (A ₇ ), the support arms (34) are connected to each other , in an articulated manner, by at least one flange (57), here called the end flange, which is parallel to the central flange or flanges (39), and which, of the same length as the latter, constitutes with the assembly a structure in the form of a deformable parallelogram, and at least one of the flanges (39, 57) is subjected to a control device (58) suitable for allowing a control of the position of the assembly relative to the annular part (10) to work.

22. Rolling machine according to any one of claims 1 3 to 21, characterized in that each of the face control rollers (29) is directly rotatably mounted on its support arm (34).

23. Rolling machine according to claim 22, characterized in that each of the face control rollers (29) extends in a recess (53) of its support arm (34) which passes right through it. .

24. Rolling machine according to any one of claims 1 9 to 21, characterized in that each of the face control rollers (29) is rotatably mounted on its support arm (34) by means of a support roller (59) pivotally mounted on the support arm (34) around a pivot axis (A ₈ ), which, parallel to that (A ₆ ) of the face control roller (29), extends to distance from it.

25. Rolling machine according to claim 24, characterized in that the roller support (59) is subjected to two jacks (60, 61), which each extend respectively on either side of its tilting axis ( A ₈ ), and which bear on the support arm (34).

26. Rolling machine according to claim 25, characterized in that the jacks (60, 61) are integrated into the support arm (34).

27. Rolling machine according to any one of claims 1 3 to 26, characterized in that stop means are provided to ensure a rotation stop of the support arms (32) of the face control rollers (29).