RECIRCULATING THREADED PART AND BALL SCREW MECHANISM

Abstract

A recirculating threaded member (12) for a ball screw mechanism (10) comprises a thread (18), a housing cavity (24) in which is housed a recirculation element (22) forming a recirculation path (34) having an end zone (38) opening into the thread groove (18) and a transition zone (46) immediately adjacent to the end zone (38), the recirculation path (34) and the thread groove (18) forming a curvilinear path for a string of balls (16) of the mechanism.Viewed in cross-section perpendicular to the curvilinear trajectory, the profile of the thread groove (18) is constant, that of the end zone (38) is identical and without radial offset relative to the profile of the thread groove (18), and that of the transition zone (46) is offset in a radial direction opposite to the reference radial direction (200) relative to the profile of the end zone (38), by an offset value that varies according to a continuously increasing and differentiable function of the distance from the point of the curvilinear trajectory to the end zone (38). (Abstract figure: Figure 3).

Description

Title of the invention: RECIRCULATING THREADED MEMBER AND BALL SCREW MECHANISM TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a ball screw mechanism, and more specifically to a ball screw mechanism provided with recirculating elements intended to guide balls of the ball screw mechanism to make them leave or join a groove constituted by a thread of a recirculating threaded member or to extract them from such a groove. It relates in particular to a recirculating threaded member, which may be a screw or a nut, incorporating such a recirculating element. STATE OF THE PRIOR ART

[0002] A recirculating threaded nut for a ball screw mechanism of this type is described in DE 199 44 875 A1 and comprises a radially inwardly facing thread, at least two housing cavities each passing through a thread of the thread, and at least two recirculating elements, each associated with one of the two housing cavities and housed in the associated housing cavity.Each of the recirculation elements forms a recirculation path facing radially inwards, the recirculation path connecting together two areas of a groove in the thread of the recirculating threaded member, the two areas of the groove in the thread of the recirculating threaded member being located on either side of the thread crossed by the associated housing cavity, the recirculation path and the two areas of the thread groove forming a curvilinear path for an associated line of balls of the ball screw mechanism, the two areas of the thread groove having a constant profile, seen in section perpendicular to the curvilinear path.In this type of recirculating threaded member, the junction between the recirculating elements and the thread groove forms a discontinuity in the guidance of the balls, a discontinuity which can cause local overloading of the balls or the edge of the thread groove at the junction with the housing of the recirculating element. Each ball passage causes stresses at the edge of the thread groove, which in the long term induce premature wear of the thread groove or the balls.

[0003] In document EP 1 559 929 A2 a ball screw mechanism is described, the nut of which has a thread for guiding the balls, and is equipped with recirculation elements each housed in a housing cavity of the nut, passing through a thread of the thread, to define an S-shaped recirculation path connecting two zones of the thread groove on either side of the thread. The recirculation element has guide faces intended to deflect the balls along the S-shaped path. Each of the two The thread groove areas include a junction area with the housing cavity and with the recirculation element, which is not covered by the recirculation element. These junction areas are recessed relative to the part of the thread groove whose profile is constant, so as to increase the clearance of the balls before they come into contact with the recirculation element. The recirculation path has a profile which is identical to that of the groove junction areas. The objective is to reduce the load on the balls before they reach the recirculation element, in order to reduce the shocks induced by the passage of the balls from the recirculation element to the groove, and to increase the service life of the ball screw mechanism. This document also proposes a method for mechanized manufacturing of the nut, and in particular of the junction areas, which makes it possible to avoid a manual operation of finishing their surface condition.However, it turns out that the junction zones have an edge with the part of the thread groove whose profile is constant, which constitutes a risk of stress peaks when the balls pass. Eliminating this edge to achieve a ramp without a break in slope requires precise machining, which is all the more difficult to obtain as the junction zone is difficult to access. Statement of the invention

[0004] The invention aims to remedy the drawbacks of the state of the art and to propose a recirculation member which limits the shocks at the outlet of the recirculation elements.

[0005] To this end, according to a first aspect of the invention, a recirculating threaded member for a ball screw mechanism is provided, the recirculating threaded member defining a reference axis comprising: a thread rotated in a reference radial direction, at least one housing cavity opening into at least one groove in the thread, and at least one recirculating element housed in the housing cavity. The recirculating element forms a recirculating path having at least one end zone opening into the groove in the thread of the recirculating threaded member and a transition zone immediately adjacent to the end zone. The recirculating path and the thread groove form a curvilinear path for a line of balls of the ball screw mechanism, the thread groove having a constant profile, seen in section perpendicular to the curvilinear path.The end zone has a profile, seen in section perpendicular to the curvilinear path, identical and without radial offset relative to the profile of the thread groove, the transition zone, having a profile which, seen in section perpendicular to the curvilinear path at any point of the curvilinear path, is offset in a radial direction opposite to the reference radial direction relative to the profile of the end zone, by an offset value which varies as a function of the distance from the point of the curvilinear path to the end zone, following a continuously increasing and derivable offset function. from the end zone to one end of the transition zone opposite the end zone.

[0006] The loading and unloading of the balls is then carried out entirely at the level of the recirculation element. In the transition zone, and depending on the direction of operation of the ball screw mechanism, there is observed either a progressive decrease in the load of the balls which move away from the thread groove, or a progressive increase in the load of the balls which move closer to the thread groove. Any ball which is in the end zone of the recirculation path is subjected to the same loads as the adjacent ball situated in the adjacent zone of the thread groove of the recirculating threaded member. This absence of variation in the ball load makes it possible to limit the risk of a point overload at the place and at the time when a ball leaves the recirculation path and comes into contact with the thread groove, and conversely, at the place and at the time when a ball joins the recirculation path and leaves the thread groove.This results in a seamless transition between the recirculation path and the thread groove of the recirculating threaded member, without having to carry out any special machining of the thread groove in the vicinity of the recirculation element.

[0007] In practice, the thread groove has a ogive profile, seen in section perpendicular to the curvilinear path. Preferably, the profile seen in section perpendicular to the curvilinear path at any point of the curvilinear path in the transition zone, is ogive. This type of profile offers the advantage of allowing precise guidance of the balls in both directions of rotation of the mechanism, and in both directions of application of axial forces on the mechanism. Naturally, the profile of the recirculation path at the end zones is then also ogive. Alternatively, an arcuate profile is also conceivable for the thread groove, and in this case also for the end zone of the recirculation path and the transition zone.

[0008] Where appropriate, it can be provided that the profile, seen in section perpendicular to the curvilinear trajectory, is identical at every point of the curvilinear trajectory in the transition zone, apart from the offset.

[0009] According to one embodiment, the recirculation element is made of a part made of a material more ductile than the thread, having a matting zone forming a continuity between the groove of the thread and the end zone of the recirculation element. This may be, for example, a metallic material such as zinc. The thread of the recirculation threaded member is made of steel, preferably having undergone at least in a surface layer a hardening treatment, for example a case hardening treatment. The matting of the end zone is obtained, for example, during a lapping of the recirculation threaded member, after its integration into a ball screw mechanism, by rolling the balls of the mechanism back and forth along the curvilinear path. The end zone caulking has the effect of filling the gap existing between the recirculating element and the housing cavity during initial assembly, made necessary by manufacturing tolerances.

[0010]

[0011]

[0012] According to one embodiment, the housing comprises two opposite walls spaced apart from each other by a distance D, measured parallel to the reference axis, such that: ^p < / ) and, preferably, lp < [), where P is the helix pitch of the thread. It is then possible to produce the housing cavity with a machining tool, for example a milling cutter, of relatively large dimensions, which reduces the machining time. Preferably, the two opposite walls are parallel and form with a plane perpendicular to the reference axis an angle equal to the helix angle of the thread. It is thus possible to maximize the width of the housing cavities while preserving the adjacent threads of the thread and their strength. According to one embodiment, the recirculation element comprises a projecting tongue forming the end zone and the transition zone, the housing cavity comprising a junction zone located in the extension of the groove of the thread, and forming a bottom turned radially in the reference direction, on which the projecting tongue bears. Thus the bearing forces of the balls on the end and transition zones of the recirculation path are directly transmitted to the zones of junctions. Where appropriate, the bottom may be flat. However, to facilitate their machining with a tool passing through the housing cavity, the bottom of the junction zone may form a concave bowl positioned in the extension of a zone of the thread groove, the depth of which, preferably, can evolve progressively from the thread groove to the corresponding housing cavity.

[0013] According to one embodiment, the recirculating threaded member is a ball screw mechanism screw, the reference radial direction being rotated radially opposite the reference axis.

[0014] According to an alternative and preferred embodiment, the recirculating threaded member is a ball screw mechanism nut, the reference radial direction being turned radially towards the reference axis. In this case, it can be provided that the housing cavity is through, which facilitates the machining of the surfaces of the cavity turned radially in the reference radial direction, namely radially inwards.

[0015] According to another aspect of the invention, it relates to a ball screw mechanism comprising two threaded members, namely a screw and a nut, one of the two threaded members being a recirculating threaded member according to one of the preceding claims, the ball screw mechanism further comprising balls forming at least one thread of balls associated with the recirculation element, and arranged along a curvilinear path passing through the recirculation path of the recirculation element and through the groove of the thread. BRIEF DESCRIPTION OF THE FIGURES

[0016] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures.

[0017] [Fig.l] [Fig.l] illustrates in isometric perspective a ball screw mechanism according to an embodiment of the invention.

[0018] [Fig.2] [Fig.2] illustrates in isometric perspective certain parts of the mechanism of ball screw of [Fig.l], namely a screw, balls and recirculating elements.

[0019] [Fig.3] [Fig.3] illustrates in exploded isometric perspective a detail of an organ recirculating threaded part of the ball screw mechanism of [Fig.l], in this case a nut, and more particularly a housing cavity and a recirculating element aligned with this housing cavity in which it is housed.

[0020] [Fig.4] [Fig.4] illustrates the recirculation element alone, in isometric view under a another angle of view.

[0021] [Fig.5] [Fig.5] illustrates a top view of a part of the nut, in line with the housing cavity of [Fig.3].

[0022] [Fig.6] [Fig.6] illustrates in axial section a part of the nut, at the right of the cavity housing of [Fig.3].

[0023] [Fig.7] [Fig.7] illustrates the recirculation element alone, in the same view plane than [Fig.6].

[0024] [Fig.8] [Fig.8] illustrates in isometric perspective, in section along a plane of section (Bl) and in section along a plane tangent to a curvilinear trajectory of recirculation of the balls, the positioning of a ball in an area of ​​a groove of a thread of the threaded recirculation member, directly near a recirculation element.

[0025] [Fig.9] [Fig.9] illustrates in isometric perspective, in section along a plane of section (B2) and in section along a plane tangent to a curvilinear trajectory of recirculation of the balls, the positioning of a ball in an end zone of a recirculation path of the recirculation element.

[0026] [Fig. 10] [Fig. 10] illustrates in isometric perspective, in section along a plane of section (B3) and in section along a plane tangent to a curvilinear recirculation trajectory of the balls, the positioning of a ball in a transition zone of the recirculation path of the recirculation element, near the end zone.

[0027] [Fig. 11] [Fig. 11] illustrates in isometric perspective, in section along a plane of section (B4) and in section following a plane tangent to a curvilinear trajectory of recir ball movement, positioning a ball in the transition zone of the recirculation path of the recirculation element, near a middle zone of the recirculation path.

[0028] [Fig. 12] [Fig. 12] illustrates in isometric perspective, in section along a plane of section (B5) and in section along a plane tangent to a curvilinear trajectory of recirculation of the balls, the positioning of a ball in the middle zone of the recirculation path.

[0029] [Fig. 13] [Fig. 13] illustrates in section along a plane tangent to a trajectory curvilinear recirculating ball mechanism, positioning a recirculating element in a housing cavity of the recirculating threaded member of the ball screw mechanism of [Fig.l], at the time of assembly, before running-in of the ball screw mechanism.

[0030] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of an embodiment

[0031] The figures illustrate a ball screw mechanism 10 comprising two threaded members, namely a nut 12 and a screw 14 aligned on a common reference axis 100, and balls 16, arranged between a thread 18 of the nut 12 and a thread 20 of the screw 14, to guide the relative helical movement between the nut 12 and the screw 14. Each thread 18, 20 comprises a helical groove whose flanks form a helical thread, following a profile which is constant in any cutting plane perpendicular to the helical thread.

[0032] One of the two threaded members, in this embodiment the nut 12, will be referred to hereinafter as a recirculating threaded member, because it is equipped with recirculating elements 22. Each of the recirculating elements 22 is housed in an associated housing cavity 24, formed in the recirculating threaded member 12, and which passes through a thread 26 of the thread 18 of the recirculating threaded member 12, to open onto two zones 28 of the groove of the thread 18 on either side of the thread 26. The housing cavities 24 are here oriented radially and are through-holes. Each housing cavity 24 has side walls 242 parallel to a radial direction of the housing cavity 24, and two junction zones 244 with the two zones 28 of the groove of the thread.These junction zones 244 here have a concave bottom, turned radially in a radial direction of reference 200 of the recirculating threaded member 12, towards the other threaded member 14, and in this case, in the case of a nut, radially towards the reference axis 100.

[0033] In this embodiment, the housing cavities 24 and the recirculation elements 22 are six in number (four of which are visible in FIG. 1 and five in FIG. 2), and each of the recirculation elements 22 defines, with the zones 28 of the thread groove on either side of the thread 26, a curvilinear trajectory over one revolution. for a line of balls 16. The six housing cavities 24 are arranged at a distance from the from each other along the axis 100 of the recirculating threaded member 12, distant axially by a distance greater than one helix pitch P of the thread of the threaded member to recirculation, and angularly offset at 90° from each other. We will understand however, in other embodiments, the number N of housing cavities 24 can be any. For a balanced and compact layout, we can choose an angular offset of and an axial distance equal to p between two cavities of adjacent housing 24, where K is a non-zero integer less than or equal to N. In the case of [Fig.l], N=6 and K=4. What applies to the housing cavities 24 naturally applies to the associated recirculation elements 22. This arrangement is not, however, imperative. For example, it may be chosen to align the housing cavities 24, to facilitate the assembly of the recirculation elements 22.

[0034] The housing cavities 24 are relatively wide in the sense that the opposite side walls 242 of a housing cavity 24 are spaced apart from each other by a distance D, measured parallel to the reference axis 100, such that ■ ~P < [) < 2P eF preferably, lp < £) < 2P- These opposite side walls 242 are preferably parallel to the helical thread 26 of the thread 18.

[0035] Each recirculation element 22 has lateral faces 222 shaped to come into adjusted contact with the lateral faces 242 of the associated housing cavity 24, and two projecting tabs 224, shaped to come and be housed in the junction zones 244 of the associated housing cavity 24, in contact with the bottom of these junction zones 244. Each recirculation element 22 has a functional face 228 which, when the recirculation element is housed in the housing cavity 24, is turned in the reference direction 200 of the threaded recirculation member 12. On the functional face 228 is formed a recirculation path 34. The recirculation path culation 34 has two end zones 38 formed at the projecting tabs 224. When the recirculation element 22 is housed in the associated housing cavity 24 of the recirculating threaded member 12, the end zones 38 of the recirculation path 34 are arranged in alignment with the zones 28 of the groove of the thread 18 on either side of the thread 26 of the recirculating threaded member 12.

[0036] The recirculation path 34 defines a recirculation trajectory, preferably in an S shape, with a middle zone 44 connected to the end zones 38 by two curved transition zones 46 ensuring two changes of direction.

[0037] Each recirculation element 22 is preferably in the form of a metal part, or alternatively in resin or plastic, preferably in one piece, and at least one demolding direction can be defined, in which this one-piece part does not have an undercut, so that it is possible to manufacturing the single-piece part by molding in a mold with axial movement in the demolding direction. In this case, the demolding direction coincides with the radial direction when the single-piece part is positioned in the housing cavity 24. This arrangement is not, however, imperative, and a more complex part can be provided, with undercuts, which can be manufactured by additive manufacturing, for example.

[0038] The groove of the thread 18 of the recirculating threaded member 12 has a constant profile, preferably a ogive profile, as does the groove of the thread 20 of the other threaded member 14.

[0039] The evolution of the profile of the recirculation path 34, seen in section perpendicular to the direction of the recirculation trajectory, at different points of the recirculation trajectory, will now be discussed with the support of figures 8 to 12.

[0040] [Fig. 8] illustrates a ball 16 located in a section plane B1, at the level of a zone 28 of the groove of the thread 18 adjacent to an end zone 38 of the recirculation path 34. This ball 16 transmits to the zone 28 of the groove of the thread a force whose radial component F1 has been represented.

[0041] Remarkably, and as illustrated in [Fig. 9], each end zone 38 of the recirculation path is formed in the continuity of the associated zone 28 of the groove of the thread 18 of the recirculating threaded member 12, with a profile, seen in section perpendicular to the curvilinear path, identical and without radial offset relative to the constant profile of the two zones 28 of the groove of the thread illustrated in [Fig. 8]. It follows that the ball 16 located in the section plane B2 of [Fig. 9] is subjected, in a load case identical to that of [Fig. 8], to a force whose radial component F2 has the same amplitude as that of F1.

[0042] The two transition zones 46, each connecting an end zone 38 to the middle zone 44, each have a profile which progressively shifts in a radial direction opposite to the reference radial direction 200, relative to the profile of the associated end zone 38, by an offset value which varies as a function of the distance from the point of the curvilinear trajectory to the end zone 38, according to a continuously increasing offset function derivable from the associated end zone 38 to the middle zone 44, to connect without discontinuity on the one hand to the profile of the middle zone 44 and on the other hand to the profile of the associated end zone 38. This is what is illustrated in Figures 10 and 11, [Fig. 10] illustrating a reduction in the radial component of the load transmitted by the ball to the transition zone 46 of the recirculation path 34 in a plane B3, and [Fig.11] a cancellation of the radial component of the load in a plane B4 closer to the middle zone 44. The middle zone 44 of the recirculation path 34 has a profile which is radially offset from the profile of the two end zones 38, in one direction. radial opposite to the reference radial direction 200, such that there is a constructive clearance between the ball 16 and the recirculation path 34, as illustrated in [Fig. 12].

[0043] Guided along a curvilinear path defined by two adjacent zones 28 of the thread groove, on either side of a thread 26 of the recirculating threaded member 12, and by an associated recirculating element 22, as well as by the thread 20 of the other threaded member 14 of the ball screw mechanism 10, the balls 16 form a continuous line, the clearance existing between two adjacent balls being less than the radius of the balls 16, and preferably less than 1 / 10th of the radius of the balls.

[0044] To the extent that there is no radial offset between the profile of the end zones 38 of the recirculation path 34 and the adjacent zones 28 of the thread groove of the recirculating threaded member 12, the ball or balls 16 penetrating at a given instant at a first of the end zones 38 in a direction of rotation of the ball screw mechanism 10, are subjected to the same loads as the balls located in the adjacent zone 28 of the thread groove.It is only when they approach the first transition zone in the direction of rotation of the mechanism that the balls 16 are progressively unloaded and lifted by the neighboring balls and by the thread of the other threaded member 14 at the central zone, before entering the second transition zone, then the second end zone 38, thus progressively returning to a load level identical to the load level in the adjacent zone 28 of the thread groove, before leaving the recirculation path 34 and continuing their advance on the adjacent zone 28 of the thread groove. Thus the load variations of the balls 16 take place in a controlled manner in the recirculation element 22 and no longer in a zone of the thread groove 18 of the recirculating threaded member 12.

[0045] The radial load exerted by the balls 16 on the recirculation element 22, essentially at the end zones 38 of the recirculation path, is transmitted to the walls of the junction zones 244 of the housing cavity 24, which ensure the radial retention of the recirculation element 22.

[0046] In the description which has just been given in support of Figures 8 to 12, the end zone 38 of the recirculation element 22 is positioned in the complete continuity of the groove of the thread 18, under operating conditions after running-in of the ball screw mechanism 10. At the time of assembly of the recirculation element 22 in the housing cavity 24, the constructive clearances and manufacturing tolerances do not allow such continuity to be ensured. On the contrary, and as illustrated in [Fig. 13], there exists at the time of assembly a discontinuity, and more specifically a gap 50, between the groove of the thread 18 and the end zone 38 of the recirculation element. The objective of running-in is to fill this gap 50 by matting the ductile material constituting the recirculation element 22. This is in provision of this matting that an excess thickness of material is deliberately formed in the end zone 38, and where appropriate in the transition zone 46 of the recirculation element 22. The matting has the effect of spreading the excess material from the end zone 38, and where appropriate in the transition zone 46 of the recirculation element 22, into the gap 50, to form a matting zone 48 there. The volume of excess material must preferably be equal or substantially equal to the volume of the gap. Where appropriate, leakage zones for the excess material may be provided, outside the rolling zone, so that if the volume of excess material is greater than the volume of the gap, material can spread into the leakage zones once the gap is filled.

[0047] Naturally, the example shown in the figures and discussed above is given for illustrative purposes only. The preceding description is transposable to a recirculating threaded member constituted by a ball screw mechanism screw. The profile of the groove of the thread 18 of the recirculating threaded member 12, in a plane perpendicular to the path of the balls 16, is preferably ogival, but may be arcuate, or V-shaped.Furthermore, the preceding description is also transposable to a recirculating threaded member whose recirculating elements span several threads of the thread, or to a recirculating threaded member comprising a recirculating channel opening into two separate housing cavities located axially at a distance from each other and separated by several threads of the thread, each housing cavity being occupied by a recirculating element comprising an end zone, a transition zone, then a connection zone with the recirculating channel.

Claims

Claims

1. A recirculating threaded member (12) for a ball screw mechanism (10), the recirculating threaded member (12) defining a reference axis (100) comprising: - a thread (18) rotated in a reference radial direction (200), - at least one housing cavity (24) opening into at least one groove of the thread (18), and - at least one recirculating element (22) housed in the housing cavity (24), the recirculating element (22) forming a recirculating path (34) having at least one end zone (38) opening into the groove of the thread (18) of the recirculating threaded member (12) and a transition zone (46) immediately adjacent to the end zone (38), the recirculating path (34) and the thread groove (18) forming a curvilinear path for a line of balls (16) of the mechanism ball screw (10), the thread groove (18) having a constant profile, seen in section perpendicular to the curvilinear path,characterized in that the end zone (38) has a profile, seen in section perpendicular to the curvilinear path, identical and without radial offset relative to the profile of the groove of the thread (18), the transition zone (46), having a profile which, seen in section perpendicular to the curvilinear path at any point of the curvilinear path, is offset in a radial direction opposite to the reference radial direction (200) relative to the profile of the end zone (38), by an offset value which varies as a function of the distance from the point of the curvilinear path to the end zone (38), according to a continuously increasing offset function and derivable from the end zone (38) to an end of the transition zone (46) opposite the end zone (38).,

2. Recirculating threaded member (12) according to claim 1, characterized in that the thread groove (18) has an ogive profile, seen in section perpendicular to the curvilinear path.

3. A recirculating threaded member (12) according to any preceding claim, characterized in that in the transition zone (46), the profile seen in section perpendicular to the curvilinear path in any point of the curvilinear trajectory is ogive.

4. Recirculating threaded member (12) according to any one of the preceding claims, characterized in that the profile, seen in section perpendicular to the curvilinear path, is identical at any point of the curvilinear path in the transition zone, apart from the offset.

5. A recirculating threaded member (12) according to any one of the preceding claims, characterized in that the recirculating element is made of a part made of a material more ductile than the thread, having a matting zone (48) forming a continuity between the groove of the thread and the end zone of the recirculating element.

6. Recirculating threaded member (12) according to any one of the preceding claims, characterized in that the housing cavity (24) comprises two opposite walls (242) spaced from each other by a distance D, measured parallel to the reference axis (100), such that: jP <D et, de préférence,}P<D 4 où P est le pas d’hélice du filetage.

7. Recirculating threaded member (12) according to claim 6, characterized in that the two opposite walls (242) are parallel and make with a plane perpendicular to the reference axis (100) an angle equal to the helix angle of the thread.

8. Recirculating threaded member (12) according to any one of the preceding claims, characterized in that the recirculation element comprises a projecting tongue (224) forming the end zone (38) and the transition zone (46), the housing cavity (24) comprising a junction zone (244) located in the extension of the thread groove, and forming a bottom turned radially in the reference direction (200), on which the projecting tongue (224) bears.

9. Recirculating threaded member (12) according to claim 8, characterized in that the bottom of the junction zone (244) forms a concave bowl positioned in the extension of a zone of the thread groove.

10. A recirculating threaded member (12) according to any one of claims 1 to 9, characterized in that the recirculating threaded member (12) is a ball screw mechanism screw, the reference radial direction (200) being rotated radially away from the reference axis (100).

11. A recirculating threaded member according to any one of claims

12.

13. 1 to 9, characterized in that the recirculating threaded member (12) is a ball screw mechanism nut (10), the reference radial direction (200) being turned radially towards the reference axis (100). Recirculating threaded member (12) according to claim 11, characterized in that the housing cavity (24) is through. A ball screw mechanism (10) comprising two threaded members, namely a screw and a nut, one of the two threaded members being a recirculating threaded member (12) according to one of the preceding claims, the ball screw mechanism (10) further comprising balls (16) forming at least one line of balls associated with the recirculating element (22), and arranged along a curvilinear path passing through the recirculating path (34) of the recirculating element (22) and through the thread groove (18).