FR3069294B1 - METHOD FOR MANUFACTURING A MONOBLOC MONOBLOC METAL RING OF SMOOTH OR BEARING BEARING, AND BEARING COMPRISING AT LEAST ONE RING OBTAINED BY THE PROCESS - Google Patents

Abstract

To manufacture a one-piece (12, 14, 14.1, 14.2) plain bearing or rolling bearing metal ring (10) having at least one open-pore structural metal foam zone (12B, 14B, 14.1B, 14.2B) and a peripheral solid area (12A, 14A, 14.1A, 14.2A) at least partially covering the metal foam area (12B, 14B, 14.1B, 14.2B), at least a portion of the peripheral solid area (12A, 14A, 14.1A, 14.2A) constituting an annular guide track (18, 18.1, 18.2, 20, 20.1, 20.2), a manufacturing step is carried out by casting of a blank comprising the metal foam zone with a regular structure (12B , 14B, 14.1B, 14.2B) and an unfinished peripheral full area, followed by a finishing step of the full peripheral area (12A, 14A, 14.1A, 14.2A), the finishing step of the solid area device having at least one finishing step of the annular guide track (18, 18.1, 18.2, 20, 20.1, 20.2). For the casting step, a destructible core (58) having open pores is inserted into a casting mold (52), a void volume (60) being preserved between the destructible core (58) and at least one wall of the mold and casting a molten metal material into the casting mold (52) so that the molten metal material fills the void volume (60) and the open pores of the destructible core (58), and destroys the destructible core. (58) after solidification of the metallic material.

Description

METHOD FOR MANUFACTURING A LAMINATED OR BEARING BEARING SMOOTH MONOBLOC METAL RING, AND BEARING COMPRISING AT LEAST ONE RING OBTAINED BY THE PROCESS

TECHNICAL FIELD OF THE INVENTION

The invention relates to the manufacture of a lightened guide ring for a plain or rolling bearing, this ring comprising an annular guide track, which may be a sliding track for a plain bearing or a bearing track. bearing for a rolling bearing.

STATE OF THE PRIOR ART

The bearings used to guide the rotation of the robot arms are generally very rigid, because they are subject to high accelerations and forces in variable directions, and must guarantee high performance in terms of accuracy. It follows massive steel constructions, which have a mass and a high moment of inertia. There is however a class of applications less demanding in terms of rigidity, and which would benefit from less massive bearings. This class of applications includes, for example, personal assistance robots or collaborative robots.

In the document US2002174545 is disclosed a lightened bearing module adapted to this class of applications, which comprises composite bearing rings, consisting of diffusion welded steel raceways on light alloy bushing bodies. The ring bodies perform the functions of interfacing the module to the outer elements of the robot arm and are for this purpose provided with fixing holes. The steel tracks ensure the rotation guiding function. But the relief is obtained at the cost of a particularly complex and expensive manufacturing process.

In FR3032017 is proposed a bearing module comprising: an outer race of steel bearing defining a reference axis and forming an annular outer race turned radially inwardly, a first inner race of steel bearing forming a first annular inner race turned radially outward facing the outer raceway, an outer alloy interface ring of light alloy, integral with the outer race ring, an inner interface ring of light alloy, integral with the first inner race, and first rolling bodies traveling on the outer raceway and on the first inner raceway for guiding a relative rotational movement between the outer interface ring and the inner interface ring around the reference axis. Remarkably, the outer interface ring is a one-piece piece forming a radially inwardly facing shrink fit extending axially from a transverse bearing shoulder of the outer interface ring to a flap of the outer interface ring projecting radially inwardly from the frettage bearing surface of the outer interface ring, the outer race being shrunk into the shrink fit of the outer interface ring; in direct or indirect support against the transverse support shoulder of the outer interface ring and against the material flap of the outer interface ring. Similarly, the inner interface ring is a one-piece piece forming a radially outwardly facing shrink-fit extending from a bearing shoulder of the inner interface ring to a material flap of the an inner interface ring projecting radially outwardly from the shrink fit of the inner interface ring, the first inner race being shrunk onto the shrink fit of the inner interface ring, in abutment directly or indirectly against the transverse support shoulder of the inner interface ring and against the material flap of the inner interface ring. The term "light alloy" here in particular means a less dense alloy than the steel of the rolling rings, in particular an alloy of aluminum or titanium, having a ductility sufficient for the formation of a flap of material. The light alloy may be different for the inner interface ring and the outer interface ring.

This solution, however, requires consideration of the differential thermal expansion between the steel bearing rings and the light alloy interface rings, which induces stresses at the hooping. This thermal behavior can be accentuated especially if the geared motor that drives the robot arm has a poor performance and causes overheating. In addition, the dimensional tolerances requirements may be difficult to meet with a light alloy and a fretted assembly.

In the document W02014166486 is described a guide ring for a rolling or plain bearing, this ring comprising a load zone, a fixing zone, and an intermediate damping zone between the load zone and the zone of fixation. The load zone forms an annular guide track, which may be a sliding track for a plain bearing or a raceway for a rolling bearing. The attachment area can form a hooping range. The intermediate damping zone consists of one or more cavities, filled with a filling material which may be a metal foam. It is envisaged to manufacture these three zones separately before assembling them, or to manufacture them in one piece. But the filling material is in any case independently constituted by the charging, fixing and damping zones and is assembled so as to fill the cavities. The cavities of the intermediate damping zone are separated from each other by bridges of materials which connect the fastening zone to the load zone, these material bridges ensuring the structural rigidity of the ring. Thus, the filler plays no role in the transmission of static charges and does not respond to a problem of lightening the ring. It essentially contributes to imparting to the guide ring the desired acoustic damping properties.

In DE 10 2016 123 017 is described a bearing ring on which is formed a guide track, and which comprises one or more cavities, which may in particular form a honeycomb structure. This ring can be in one piece, if necessary in metal. It is proposed to manufacture this ring by an additive manufacturing process or by sintering. Such methods, however, appear to be incompatible with a high production rate.

In FR 2 921 281 is described a method of manufacturing a casting part combining solid areas and metal foam zones, using a preform consisting of aggregated elements defining between them interstices. This preform is placed in a mold leaving an empty volume between the preform and a wall of the mold, and molten metal is poured into the mold, so that the latter infiltrates on the one hand into the interstices of the preform where it constitutes a metal foam zone, and fills the other empty volume where it constitutes a solid area of the room. After solidification of the metal, the preform is destroyed and evacuated. The document FR 2 927 269 specifies a possible structure of the preform, which facilitates its destruction and evacuation by vibration and / or dissolution.

STATEMENT OF THE INVENTION

The invention aims to overcome the disadvantages of the state of the art and to provide a lighter guide ring, compatible with a simple industrial manufacturing process.

To do this is proposed, according to a first aspect of the invention, a method of manufacturing a one-piece bearing or plain bearing metal ring, the one-piece metal ring comprising at least one metal foam zone with a regular structure with open pores and a full peripheral zone at least partially covering the metal foam zone, at least a portion of the full peripheral zone constituting an annular guide track. This method comprises a step of manufacturing by casting a blank comprising the metal foam zone and an unfinished peripheral full zone, followed by a finishing step of the full peripheral zone, the finishing step of the full peripheral zone. comprising at least one finishing step of the annular guide track.

By monoblock metal ring means here a metal ring in one piece, with a structural continuity including between the full peripheral zone and the metal foam zone. In particular, the different zones of the one-piece metal ring consist of the same metallic material, so that the thermal expansions of the ring are homogeneous and that, in particular, there are no stresses or gaps induced by expansion. differential.

By metal foam is meant here a honeycomb structure of a metal material (metal or alloy), having a high porosity, greater than 50%. The metal foam has a regular structure when the pore geometry is ordered and predetermined, as opposed to so-called stochastic metal foams.

The pores obtained by the casting process are preferably open, which offers, when the ring is in use, a large heat exchange area, which can be used to cool the ring and the bearing which incorporates it, placing the ring in a natural or forced flow of a coolant, which can be gaseous or liquid.

The annular guide track, where the load is concentrated, is formed by the full peripheral zone, while the parts of the metal ring least exposed to stress peaks are constituted by the metal foam zone, promoting lightening of the ring and the bearing which incorporates it, without harming the mechanical resistance. If necessary, more than one annular guide track can be formed on the full peripheral area. The ring may optionally be constituted by the full peripheral zone and the metal foam zone. Alternatively, the ring may comprise, in addition to the full peripheral zone and the metal foam zone, one or more interior solid zones, surrounded by the metal foam zone.

The foundry process achieves higher industrial rates than other processes, including additive manufacturing.

According to one embodiment, during the casting step, a destructible core having open pores in a casting mold is inserted, a peripheral empty volume being preserved between the destructible core and at least one wall of the casting mold. mold, then casting a molten metal material inside the casting mold so that the molten metal material fills on the one hand the void volume device where it constitutes the unfinished peripheral full area and on the other hand the open pores the destructible core where it constitutes the metal foam zone, then destroys and destroys the destructible core after solidification of the metal material. By this process, the metal foam is open-pore. The solidified metal material is, in its part filling the space between the core and the wall of the mold, the unfinished peripheral full area, and in its part filling the open pores of the destructible core, the metal foam. The destructible nucleus may have no contact with the walls of the mold except for a few point areas of contact, so that the empty volume completely surrounds the destructible nucleus. Alternatively, the destructible core may be in surface support on one or more of the walls of the mold. The destructible core may itself surround an empty interior volume which, after filling with the molten metal material, constitutes a solid interior zone.

The cavity of the casting mold defines a reference axis which is also the axis of revolution of the annular guide track, and which may be an axis of symmetry of revolution of the mold cavity. The introduction of the molten metal material into the mold is through one or more tapholes in the walls of the mold. These casting holes may include in particular: one or more tapholes oriented parallel to the reference axis and opening on a transverse wall of the mold cavity; and / or one or more casting holes oriented radially with respect to the reference axis and opening onto an axisymmetric wall of the mold cavity.

According to one embodiment, all the casting holes open into the empty volume.

According to another embodiment, only some of the tapping holes open into the empty volume, others opening on a wall of the mold in direct contact with the destructible core.

The core may in particular be destroyed by vibration and / or dissolution.

Preferably, the method comprises a step of manufacturing the destructible core comprising a step of aggregating elements using a binder, leaving between the aggregated elements interstices constituting the open pores.

Alternatively, the method comprises a step of manufacturing the destructible core having an outer shell enclosing elements, interstices constituting the open pores being preserved between the elements. The nucleus is then destroyed in two stages, first of all by destroying the hull and then dissolving the elements it contained.

These techniques make it possible, if necessary, to produce pores having a truncated Kelvin octahedron shape, which makes it possible to obtain a metal foam zone that complies with the Plateau conditions. In particular, documents FR 2 921 281 or FR 2 927 269 may be referred to for a description of the foundry molding step.

According to an alternative embodiment, it is conceivable that the foundry manufacturing step comprises several successive sub-steps, namely a substep of manufacturing a closed-pore metal foam zone, and then a remoulding of the metal foam zone in a mold, so as to define a peripheral empty volume between the metal foam zone and at least one wall of the mold, then filling the mold so that the molten metal material merges with the periphery adjacent to the foamed metal zone and define the unfinished full peripheral area. The manufacture of the closed-pore metal foam zone may be effected by injection of a gas or a mixture of a foaming agent into a liquid metal.

The thickness of the full peripheral zone must be adapted to the intended application. Preferably, the finished full peripheral zone has, at the level of the annular guide track, a thickness greater than 1 mm, preferably greater than 2 mm. Preferably, the finished full peripheral zone has, at the level of the annular guide track, a thickness of less than 5 mm, preferably less than 3 mm. These dimensions are particularly adapted to the application of the invention to the guidance of a robot arm, in particular a personal assistance robot or collaborative robot.

Preferably, the finished peripheral solid zone has, at the level of the annular guide track, a thickness of less than 20%, preferably less than 10% of the thickness of the ring. The lightening effect is then particularly sensitive.

In practice, the guide track is a rolling track or sliding, which must undergo finishing operations. Thus, according to one embodiment, the finishing step of the full peripheral zone comprises a grinding and / or superfinishing at least of the annular guide track. According to one embodiment, the finishing step of the full peripheral zone comprises a heat treatment step.

According to one embodiment, the finishing step of the full peripheral zone comprises a step of deformation, in particular of pegging, punching or crimping.

Preferably, the metal foam zone is axisymmetric. The axis of revolution defined by the annular guide track being taken as the reference axis of the ring, the annular zone of metal foam may be radially outside the guide track, assuming that the track of guiding is an outer sliding or rolling track, turned radially inwards. Alternatively, the annular zone of metal foam may be located radially inside the guide track, assuming that the guide track is an inner sliding or rolling track, turned radially outwards. According to another embodiment, the guide track can be turned in the axial direction and be positioned on a transverse face of the ring, at least a portion of the annular region of metal foam being positioned axially recessed with respect to this transverse face. .

[0030] Preferably, the metal foam zone has a volume average porosity level greater than 60%, preferably greater than 70%, preferably greater than 75%, preferably greater than 80%, and preferably less than 80%. 90%. The relief obtained is particularly important. The porosity rate can be constant throughout the metal foam zone, or variable. In particular, it is possible to envisage a density that varies monotonically with the distance to the reference axis, or with the distance to the full peripheral zone. It is also possible to envisage a zone of metal foam whose porosity rate is lower in a restricted angular zone around the reference axis, corresponding to a main load zone under the operating conditions of the plain or rolling bearing whose ring is part.

In practice, the full peripheral zone may be unitary or subdivided into several sub-zones. The one-piece metal ring may further comprise a solid inner zone, where appropriate subdivided into several sub-zones. The metal foam zone can also be subdivided into several sub-zones. Thus, for example, the solid peripheral zone may cover two opposite faces of the ring, and the latter may comprise a solid internal zone consisting of walls or partitions which connect the two opposite faces, the zone of metallic foam being subdivided into sub-zones. separated by each other by the partitions. The opposite faces may for example be two transverse faces of the ring, perpendicular to the axis of revolution of the ring. Alternatively, the opposite faces may consist of a face turned radially inwardly and a face turned radially outwardly. The partitions preferably extend in planes passing through the axis of revolution of the ring.

Where appropriate, the full peripheral zone may completely cover the metal foam.

According to one embodiment, the finished peripheral full zone comprises a shrinking seat, preferably cylindrical, preferably facing away from the annular guide track, respectively. This hooping range allows the attachment of the ring to a rotating member.

According to one embodiment, the finished full peripheral zone comprises an annular groove for fixing a seal.

In a particularly advantageous manner, the one-piece metal ring comprises cylindrical fixing holes. These fixing holes can be threaded or not, blind or through. They can be oriented parallel to the axis of revolution of the metal ring, and distributed around the axis of revolution. Alternatively, they can be oriented in a direction perpendicular to a plane containing the axis of revolution. They can also be oriented radially, or at a solid angle whose apex passes through the axis of revolution of the bearing.

According to one embodiment, at least one of the cylindrical fixing holes is formed in the full peripheral zone.

According to one embodiment, at least one of the cylindrical fixing holes is formed within the metal foam zone and constitutes a housing of a fixing insert, in particular a fixing sleeve. The insert may in particular take the form of a metal sleeve, threaded or not.

Preferably, the one-piece metal ring is made of steel, preferably in a rolling steel grade, in particular a grade 100 Cr 6.

The guide track may in particular be a raceway. The shape of the raceway will be adapted to the type of rolling bodies used, which may be cylindrical or frustoconical rollers, barrels or balls, or more generally solid revolution. If necessary, several coaxial raceways can be formed on the full peripheral zone.

According to another aspect of the invention, it relates to a guide ring, in particular a bearing ring or plain bearing, obtained by the method described above.

According to another aspect of the invention, it relates to a rolling bearing comprising at least a first race, a second race and rolling bodies capable of rolling on a first raceway. of the first race and a second raceway of the second race when the first race rotates relative to the second race about an axis of revolution of the rolling bearing, characterized in that at least one of the first and second bearing rings is a one-piece metal ring obtained by the method described above.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent on reading the description which follows, with reference to the appended figures, which illustrate: FIG. 1, an axial sectional view of a bearing comprising two bearing rings according to one embodiment of the invention; Figure 2 is a front view, with a sectional detail, of a wheel bearing comprising three bearing rings according to a second embodiment of the invention; Figure 3 is an axial sectional view of the wheel bearing of Figure 2; FIG. 4 is an axial sectional view of a rolling thrust bearing comprising two bearing rings according to a third embodiment of the invention; Figure 5 is an axial sectional view of an angular contact bearing comprising two bearing rings according to a third embodiment of the invention; Figure 6 is an axial sectional view of a rolling bearing with two rows of rolling bodies comprising three bearing rings according to a fourth embodiment of the invention; FIG. 7 is a view in axial section of a step of manufacturing by casting of a blank of a guide ring, according to a manufacturing method according to one embodiment of the invention.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

In Figure 1 is illustrated a bearing 10 of the robot arm, comprising an outer race 12 of rolling steel, a bearing inner ring 14 of steel, and a row of rolling bodies 16.1, 16.2 circulating on paths of annular bearings 18.1, 18.2, 20.1, 20.2 formed on the outer ring 12 and the inner ring 14 for rotating the outer ring 12 and the inner ring 14 about an axis of revolution in rotation relative to each other; 100 common defined by the tracks.

More specifically, each ring 12, respectively 14, comprises two raceways 18.1, 18.2, respectively 20.1, 20.2 forming an axial section at a right angle, and the rolling bodies 16.1, 16.2 are rollers arranged to form a row of crossed rollers, alternately including first rollers 16.1 oriented to roll on a first race 18.1 of the outer race 12 and a first race 20.1 of the inner race 14, and second rollers 16.2 rolling on a second path 18.2 of the outer ring 12 and a second race 20.2 of the inner ring 14.

The outer ring 12 further comprises a radial insertion well 22 passing radially closed by a plug 24 whose end facing the inner race ring 14 is shaped to be in continuity with the raceways 18.1, 18.2. of the outer bearing ring 12. An axial pin 26 passing through a bore 28 formed in the outer ring 12 makes it possible to secure the positioning of the plug 24 in the well 22.

The outer ring 12 has threaded fixing holes 30 parallel to the reference axis. These fixing holes 30 are distributed around the circumference of the ring 12 and open onto an annular flat face of interfacing 32 of the outer ring 12. They are intended to allow the attachment of the outer ring 12 to a robot arm member. .

The inner ring 14 also comprises a circular row of threaded blind mounting holes 34 parallel to the reference axis 100 and opening on a flat interfacing face 36. The inner ring 14 forms a hooping surface 38 to allow interfacing with robot arm member.

The bearing 10 is optionally provided with a sealing device 40, in this case in the present case a seal 42 made of elastomer molded on a rigid frame 44, for example metal. The seal 42 is mounted on a bearing surface 46 of the outer ring 12 and slidingly bears on a sliding track 48 constituted by a ground surface of the inner ring 14. The support of the seal 42 on the sliding track 48 is provided by a spring 50.

Remarkably, each of the rings 12,14 consists of a single piece and comprises a full peripheral zone 12A, 14A, that is to say without porosity, also called "skin", and an area of metal foam 12B, 14B. In this embodiment, the solid peripheral zone 12A, 14A completely covers the metal foam zone 12B, 14B. It forms in particular the areas under load, in particular the raceways 18.1, 18.2, 20.1, 20.2, as well as the interfacing walls 32 and the walls of the fixing holes 30, 34, of the bore 28 and the well. 22 as well as the hooping surface 38. It also constitutes the attachment surface 46 of the seal and the opposite sliding track 48.

In known manner, the assembly of the bearing comprises a step of insertion of the rolling bodies 16.1,16.2 between the bearing rings 12,14 through the well 22 after the races 18.1,18.2 of the outer ring 12 have been positioned opposite the races 20.1, 20.2 of the inner ring 14.

It should be noted that the rolling bodies 16.1,16.2 are shown in the form of rollers 26.1 of a row of crossed rollers, but that we can alternatively provide other types of rolling bodies, including balls, the raceways may be optionally shaped warhead, so as to achieve three or four points of contact per ball.

Figures 2 and 3 is illustrated a rolling bearing wheel 10 having an outer race 12, two inner race rings 14.1, 14.2 and rolling bodies 16.1, 16.2, in this case balls, arranged in two rows so as to run on raceways 18.1, 18.2, 20.1, 20.2 formed on the outer ring 12 and on the inner rings 14.1, 14.2. The outer ring 12 further includes threaded bores 30 parallel to the axis of revolution 100 of the bearing 10, for securing the outer ring 12 to a strut. Remarkably, each of rings has a one-piece structure and consists of an inner zone of metal foam, and a full peripheral zone which completely covers the inner zone.

In Figure 4 is illustrated a thrust ball bearing 10, comprising two metal rings monobloc rolling 12,14 on which are formed raceways 18, 20 guiding the circulation of rolling bodies 16 consist of balls. Remarkably, each ring 12, 14 consists of a peripheral solid zone 12A, 14A on which is formed the raceway 18,20, and a metal foam zone 12B, 14B forming the portion of the ring 12 , 14 farthest from the raceway 18, 20. In contrast to the previous embodiments, the full peripheral zone 12A, 14A does not cover the faces of the ring farthest from the raceway 18, 20. The foam zone metal 12B, 14B preferably has an open or semi-open porosity, which makes it possible to consider cooling the ring by natural or forced convection, taking advantage of the large exchange surface of the metal foam zone 12B, 14B.

FIG. 5 illustrates an angular contact rolling bearing 10, whose rings 12, 14, as in the previous embodiment, each consist of a full peripheral zone 12A, 14A on which is formed a raceway 18, 20, and a metal foam zone 12B, 14B forming the portion of the ring farthest from the raceway.

In Figure 6 is shown a rolling bearing with two rows of rolling bodies, comprising an outer race 12, two inner race rings 14.1,14.2 and rolling bodies 16.1, 16.2, in this case balls. , arranged in two rows so as to circulate on raceways 18.1.18.2, 20.1, 20.2 formed on the outer ring 12 and on the inner rings 14.1, 14.2. Remarkably, each ring 12, 14.1, 14.2 consists of a peripheral solid zone 12A, 14.1A, 14.2A on which the one or more raceways are formed, and a metal foam zone 12B, 14.IB , 14.2B forming the part of the ring 12,14.1,14.2 furthest from the raceways 18.1, 18.2, 20.1, 20.2. Similar to the embodiments of FIGS. 4 and 5, and unlike the embodiments of FIGS. 1 to 3, the peripheral solid zone 12A, 14A, 14.2A does not cover the furthest faces of the ring. of the race 18.1.18.2.20.1.20.2.

In all embodiments, the raceways 18, 18.1, 18.2, 20, 20.1, 20.2 are preferably rectified, and more optimally superfinished, and have optionally undergone local heat treatment.

Naturally, the examples shown in the figures and discussed above are given for illustrative and not limiting.

FIG. 7 illustrates a step of manufacturing a guide ring according to the invention, in this case one of the inner rings 14.1 or 14.2 of FIG. 6. The step illustrated in FIG. 7 is a step of manufacturing a blank by casting in a mold 52 comprising two annular pieces 54, 56 defining a reference axis 200 of the mold 52, which is intended to coincide with an axis of symmetry of the blank and with the axis of revolution 100 of the finished inner ring. The parts 54, 56 of the mold are preferably metallic, the mold being permanent. However, a sand mold is also possible. At least one of the two mold parts, here the upper part 56, is movable in translation relative to the other part, here the lower part 54, parallel to the reference axis 200. Inside the mold has been arranged a destructible core 58 consisting of elements aggregated to each other by a binder, which preserves between the elements interstices forming open pores. The destructible core 58 is constituted according to the teaching of documents FR 2 921 281 or FR 2 927 269. The core does not occupy the entire cavity defined by the mold parts, and a volume 60 remains empty before the casting of the metallic material .

At least one of the two parts of the mold, here the fixed lower part 56, is provided with one or more tap holes 62, 64, for the introduction of a molten metal material. More specifically, there is shown here a radially oriented taphole 62 (i.e. opening into a sidewall of the cavity) and an axially oriented taphole 64 (i.e. ie opening on a wall of the cavity perpendicular to the reference axis). The radially oriented taphole 62 opens into the empty volume. The axially oriented taphole 64 opens onto a wall of the destructible core. It should be noted that this is only one of the possible provisions. It can be envisaged that no hole will open onto a wall of the destructible core. We can also consider that the holes are all of radial orientation, or all of axial orientation. The mold also has one or more vents 66.

After carrying out the remoulding operation, positioning the destructible core 58 precisely in the lower part 54 of the mold, then closing the upper piece 60 of the mold, it proceeds to the actual casting, preferably under pressure, by the tapping holes 62, 64, simultaneously or sequentially. Where appropriate, the casting may be accompanied by centrifugation around the reference axis 200, especially if the casting hole or holes open on a wall of the cavity turned radially outwardly, or a wall perpendicular to the reference axis. The casting invades the empty volume 60 and the open pores of the core 58.

Once the metal material cooled in the mold, eject the metal blank obtained (or destroys the mold if it is sand). The blank can then be immersed in a solvent to dissolve the binder and evacuate the disintegrated elements from the core.

The cooled metal material which occupied the pores of the destructible core 58 constitutes the metal foam zone 14.1B, 14.2B of the finished part. The metallic material which occupied the empty volume 60 of the cavity is intended to constitute the peripheral full zone 14.IA, 14.2A of the finished ring 14.1, 14.2. However, it remains to complete the work, carrying out various operations that may include including cutting the feed system, grinding, deburring. The completion also includes the finishing of the guide track 20.1, 20.2, here a raceway, by grinding or superfinishing. The finish of the guide track may also include a heat treatment. Other forming operations, in particular by pegging, punching or crimping can be performed.

Naturally, the foundry manufacturing process of Figure 7, described in connection with the inner rings of Figure 6, is immediately transposable to the inner and outer rings 12,14,14.1,14.2 of Figures 1 to 6.

For each of the rolling bearings of Figures 1 to 6, there is illustrated two bearing rings comprising a metal foam. But it is also conceivable that only one of the bearing rings comprises a metal foam, the other being of conventional solid structure. For a bearing whose bearing ring is "fixed" in rotation in a Galilean frame, one can for example choose to lighten only the rotating ring to minimize the moment of inertia of the rotating crew comprising the ring. For a bearing comprising an inner ring and an outer ring, it is possible for example to provide metal foam only on the outer ring, potentially more massive than the inner ring.

If the ring has inner zones subjected to high stresses in the conditions of use, it is possible to provide interior solid zones corresponding to these zones of high stresses.

The rolling bodies can be of any type. What has been shown for rolling bearings can be transposed to plain bearings.

It is explicitly provided that one can combine the different embodiments illustrated to propose others.

It is emphasized that all the features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if concretely they have been described in connection with other specified characteristics, both individually and in any combination, may be combined with other characteristics or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or meaningless.

Claims (18)

1. A method of manufacturing a one-piece (12, 14, 14.1, 14.2) bearing or rolling bearing metal ring (10), the one-piece metal ring (12, 14, 14, 14, 14) having at least one foam zone metal structure having a regular open pore structure (12B, 14B, 14.1B, 14.2B) and a peripheral solid zone (12A, 14A, 14.IA, 14.2A) at least partially covering the metal foam zone (12B, 14B, 14.1) B, 14.2B), at least a portion of the peripheral full area (12A, 14A, 14.1A, 14.2A) forming an annular guide track (18, 18.1, 18.2, 20, 20.1, 20.2), characterized in that it comprises a casting step of a blank comprising the metal foam zone (12B, 14B, 14.1B, 14.2B) and an unfinished peripheral full zone, followed by a finishing step of the full peripheral zone (12A, 14A, 14.1A, 14.2A), the step of finishing the full peripheral area (12A, 14A, 14.1A, 14.2A) having at least one step of f inition of the annular guide track (18,18.1,18.2,20, 20.1,20.2). 2. Manufacturing method according to claim 1, characterized in that during the casting step, a destructible core (58) having open pores in a casting mold (52) is inserted, a peripheral empty volume (60) being preserved between the destructible core (58) and at least one wall of the mold, and molten metal material is cast inside the casting mold (52) so that the molten metal material fills on the one hand the peripheral empty volume (60) where it constitutes the unfinished full peripheral zone and on the other hand the open pores of the destructible nucleus (58) where it constitutes the metal foam zone, then the destructible nucleus (58) is destroyed and discharged after solidification of the metallic material. 3. Manufacturing process according to claim 2, characterized in that it comprises a step of manufacturing the destructible core (58) comprising a step of aggregating elements using a binder, leaving between the elements aggregates of the interstices constituting the open pores. 4. Manufacturing method according to claim 2, characterized in that it comprises a step of manufacturing the destructible core (58) having an outer shell enclosing elements, interstices constituting the open pores being preserved between the elements. 5. Manufacturing process according to any one of the preceding claims, characterized in that the finite peripheral complete area (12A, 14A, 14.1A, 14.2A) has, at the level of the annular guide track, a thickness greater than 1mm. , preferably greater than 2mm. 6. The manufacturing method according to any one of the preceding claims, characterized in that the finite peripheral full area (12A, 14A, 14.1A, 14.2A) has, at the level of the annular guide track, a thickness less than 5. mm, preferably less than 3 mm. 7. Manufacturing method according to any one of the preceding claims, characterized in that the finite peripheral full area (12A, 14A, 14.1A, 14.2A) has, at the level of the annular guide track, a thickness of less than 20. %, preferably less than 10% of the thickness of the ring. 8. Manufacturing method according to any one of the preceding claims, characterized in that the finishing step of the full peripheral zone (12A, 14A, 14.1A, 14.2A) comprises a rectification and / or superfinishing at least of the annular guide track (18,18.1,18.2, 20, 20.1, 20.2). 9. Manufacturing process according to any one of the preceding claims, characterized in that the finishing step of the full peripheral zone (12A, 14A, 14.1A, 14.2A) comprises a heat treatment step. 10. The manufacturing method according to any one of the preceding claims, characterized in that the step of finishing the full peripheral zone (12A, 14A, 14.1A, 14.2A) comprises a step of deformation, including bouterollage, punching or crimping. 11. Manufacturing method according to any one of the preceding claims, characterized in that the metal foam zone (12B, 14B, 14.1B, 14.2B) is axisymmetric. 12. Manufacturing method according to any one of the preceding claims, characterized in that the metal foam zone (12B, 14B, 14.1B, 14.2B) has an average volume porosity greater than 60%, preferably greater than 60%. at 70%, preferably greater than 75%, preferably greater than 80%, and preferably less than 90%. 13. Manufacturing method according to any one of the preceding claims, characterized in that the finite peripheral complete area (12A, 14A, 14.1A, 14.2A) comprises a hooping surface (38, 46), preferably cylindrical, of preferably facing away from the annular guide track (20, 20.1, 20.2), respectively (18.18.1.18.2). 14. The manufacturing method according to any one of the preceding claims, characterized in that the one-piece metal ring (12,14,14.1,14.2) comprises cylindrical fixing holes (30, 34). 15. The manufacturing method according to claim 14, characterized in that at least one of the cylindrical fixing holes (30, 34) is formed in the full peripheral zone (12A, 14A, 14.1A, 14.2A). 16. Manufacturing method according to any one of claims 14 to 15, characterized in that at least one of the cylindrical fixing holes is formed within the metal foam zone (12B, 14B, 14.1B, 14.2B) and constitutes a housing of a fixing insert, in particular a fixing sleeve. 17. The manufacturing method according to any one of the preceding claims, characterized in that the one-piece metal ring (12,14,14.1,14.2) is made of steel, preferably in a steel grade, especially a 100 Cr grade. 6. 18. Roller bearing (10), comprising at least a first race (12), a second race (14,14,14,14.2) and rolling bodies (16, 16.1, 16.2) capable of rolling on a first race (18,18.1, 18.2) of the first race (12) and a second race (20, 20.1, 20.2) of the second race (14, 14.1, 14.2) when the first race ring bearing (12) rotates relative to the second race (14, 14.1, 14.2) about an axis of revolution (100) of the rolling bearing (10), characterized in that at least one of the first and second bearing rings (12, 14, 14.1, 14.2) is a one-piece metal ring obtained by the manufacturing method according to any one of the preceding claims.