CONNECTION ELEMENT, AND METHOD FOR PRODUCING A RING FOR SUCH A CONNECTION ELEMENT

Abstract

A connection element providing a first ring and a second ring, the two rings rotating relative to one another about a central axis, the first ring having a contact portion with a contact surface interacting with the second ring for the relative rotation, and a fastening portion configured to be rigidly secured to a support. The contact portion is made of a first material and the fastening portion is made of a second material, different to the first material, the first material having a hardness strictly greater than that of the second material, and the second material having a structural fatigue strength strictly greater than that of the first material.

Claims

1. A connection element comprising: a first ring, and a second ring, the two rings rotating relative to one another about a central axis, the first ring comprising a contact portion with a contact surface interacting with the second ring for the relative rotation, and a fastening portion intended to be rigidly secured to a support, wherein the contact portion is made of a first material and the fastening portion is made of a second material, different to the first material, the first material having a hardness strictly greater than that of the second material, and the second material having a structural fatigue strength strictly greater than that of the first material.

2. The connection element according to claim 1, further comprises the connection element consisting of an articulated connection, wherein the contact surface of the contact portion of the first ring is in direct sliding contact against a contact surface of the second ring.

3. The connection element according to claim 2, wherein the first material is one out of the following list: bronze, steel, cobalt alloy, titanium alloy, nickel alloy.

4. The connection element according to claim 2, wherein the second material is one out of the following list: titanium alloy, aluminium alloy, nickel alloy.

5. The connection element according to claim 2, wherein the fastening portion of the first ring consists of an annular flange extending radially.

6. The connection element according to claim 1, further comprises a bearing with roller elements, wherein at least one row of roller elements is inserted between the contact surface of the contact portion of the first ring and a contact surface of the second ring.

7. The connection element according to claim 6, wherein the first material is one out of the following list: 100C6, high speed steel M50, ASP 2060 or M62.

8. The connection element according to claim 6, wherein the second material is one out of the following list: low carbon steel, medium carbon steel, titanium alloy, aluminium alloy, M50NiL, 32CVD13, INCONEL718.

9. The connection element according to claim 1, wherein the fastening portion of the first ring is a squirrel cage comprising a radial fastening rim and an essentially axial portion with a plurality of windows distributed circumferentially.

10. A method for producing a first ring of a connection element having a first ring, and a second ring, the two rings rotating relative to one another about a central axis, the first ring comprising a contact portion with a contact surface interacting with the second ring for the relative rotation, and a fastening portion intended to be rigidly secured to a support, wherein the contact portion is made of a first material and the fastening portion is made of a second material, different to the first material, the first material having a hardness strictly greater than that of the second material, and the second material having a structural fatigue strength strictly greater than that of the first material, and comprising the following steps: (a) machining the contact portion from a bar or by additive manufacturing from the first material, the contact portion having a contact surface; (b) mounting the contact portion in a fixed support, in such a way that part of its outer surface is free; (c) storing the second material in powder form, the fastening portion being produced on the free part of the contact portion with the powder; and (d) machining the fastening portion to its final dimensions.

11. The method according to claim 10, wherein step (c) of the method is performed by 3D printing.

12. The method according to claim 10, wherein a mould having the shape of the fastening portion is mounted on the contact portion in such a way that only the surface on which the fastening portion will be formed is free inside the mould, the fastening portion being formed in step (c) by injecting the powder into the mould, which is closed, under vacuum, the shape thus obtained being consolidated by hot isostatic pressing.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] The invention will become clearer on reading the following description, provided purely by way of non-limiting example.

[0045] The description refers to the attached drawings, in which:

[0046] [FIG. 1] is a schematic view in cross section of a ball joint according to one embodiment of the invention, mounted on a shaft; and

[0047] [FIG. 2] is a schematic view in partial cross section of a bearing element with a squirrel cage according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1 shows a ball joint connection element, indicated in general with the reference sign 1, with a central axis X1.

[0049] The ball joint 1 comprises an inner ring 2 and an outer ring 3.

[0050] The inner ring 2 comprises a substantially cylindrical internal surface 4, intended to be positioned against the external periphery of a corresponding cylindrical shaft 5. The inner ring 2 further comprises an external surface 6 with the profile of a sphere, more specifically as sections of a sphere. The internal surface 4 and external surface 6 of the inner ring 2 are connected to one another by side walls 7. According to an embodiment not shown, the inner ring 2 may also have a cylindrical sleeve inserted between its internal surface 4 and the external periphery of the shaft 5. This sleeve may be made of bronze, for example.

[0051] The inner ring 2 consists of a titanium alloy, for example TA6V. Alternatively, this ring is consists of a nickel alloy, or steel.

[0052] The outer ring 3 comprises a substantially cylindrical external surface 8. The outer ring 3 further comprises an internal surface 9 which is spherical, more specifically as sections of a sphere, corresponding to that of the external surface 6 of the inner ring 2. The inner ring 2 and the outer ring 3 thus have, with respect to one another, three degrees of freedom in rotation. The internal surface 9 is connected to the external surface 8 by side walls 10. The side walls 7 of the inner ring 2 project, in axial section, on either side of the side walls 10 of the outer ring 3 in the position of FIG. 1, in which the cylindrical surface 4 is coaxial with the shaft 5.

[0053] The outer ring 3 further comprises an annular flange 11 projecting from the outer surface 8 and extending in a radial direction away from the central axis X1. The annular flange has at least one through-opening 12 provided to receive a fastening screw for rigidly securing the outer ring 3 to a support.

[0054] According to the invention, the outer ring 3 is made of two different materials. The outer ring 3 comprises a contact portion 3-1 designed to come into sliding contact against the inner ring 2 and made of a first material. The outer ring further comprises a fastening portion 3-2 made of a second material, different to the first material.

[0055] The contact portion 3-1 comprises the external surface 8 and internal surface 9, and the side walls 10. The contact portion 3-1 is made of a material having a hardness strictly greater than that of the second material. Thus, the contact portion 3-1 is made of a specific material for fulfilling the function of swiveling by direct sliding against the inner ring 2. The first material is one out of the following list: bronze, steel, cobalt alloy.

[0056] The fastening portion 3-2 consists of the flange 11 and is made of a material having an elasticity strictly greater than that of the first material. Thus, the fastening portion 3-2 is made of a specific material for withstanding loads and vibration. The second material is one out of the following list: titanium, titanium alloy, aluminium alloy, nickel alloy.

[0057] A further advantage of the present invention is that the material used for the fastening portion 3-2 is less expensive than that used for the contact portion 3-1, or indeed for an outer ring produced as a single piece and made of a material representing a compromise with respect to the requirements. The material used for the fastening portion 3-2 is also more lightweight than that used for the contact portion 3-1, or indeed for an outer ring produced as a single piece and made of a material representing a compromise with respect to the requirements. This gives a ball joint ring that can perform each of the two functions, swiveling and fastening, optimally, at lower cost and lower weight.

[0058] A second embodiment of the invention is shown in FIG. 2, in which the connection element consists of a bearing element with roller elements, indicated in general with the reference sign 20, with a central axis X20.

[0059] The bearing 20 comprises an inner ring 21, an outer ring 22, and a plurality of roller elements 23.

[0060] The inner ring 21 has a substantially cylindrical internal surface 24, a cylindrical external surface 25 forming an internal raceway for the roller elements 23, and side walls 26 connecting the internal surface 24 and external surface 25.

[0061] The inner ring 21 is made of steel, for example M50.

[0062] The outer ring 22 has a substantially cylindrical external surface 27, a cylindrical internal surface 28 forming an external raceway for the roller elements 23, and side walls 29 connecting the external surface 27 and internal surface 28.

[0063] Advantageously, the external surface 27 comprises two circumferential grooves 30, 31 that can each receive an O-ring seal (not shown), a film of fluid being provided axially between the two seals housed in the grooves 30, 31, the film being trapped radially between the external surface 27 and a surface of a fixed support (not shown) so as to form a means for attenuating vibration.

[0064] The roller elements 23 are housed between the internal raceway 25 and external raceway 28. In the example shown in FIG. 2, the roller elements 23 are cylindrical rollers of axis parallel to the central axis X1. Alternatively, the roller elements may take another form, for example balls or conical rollers.

[0065] According to the embodiment shown in FIG. 2, the outer ring 22 also has a squirrel cage 32 extending axially from a side wall 29 of the outer ring 22.

[0066] The squirrel cage 32 has a fastening rim 33 extending essentially radially and intended to be rigidly secured to a fixed support (not shown), for example by means of threaded screws passing through through-openings 34 and being received in corresponding tapped holes in the support. The squirrel cage 32 further comprises an intermediate portion 35 that is essentially axial with a plurality of windows 36 distributed circumferentially so as to give the cage 32 a degree of flexibility so as to withstand various types of vibration of the assembly. According to the embodiment shown in FIG. 2, the intermediate portion 35 comprises two axial portions 35-1, 35-2, each with windows 36, the axial portion 35-2 having a diameter greater than the diameter of the axial portion 35-1. The two axial portions 35-1, 35-2 are connected by a bent portion 35-3. The fastening rim 33 extends radially from a free end of the axial portion 35-2 of greater diameter.

[0067] According to the invention, the outer ring 22 is made of two different materials. The outer ring 22 comprises a contact portion 22-1 designed to come into bearing contact against the roller elements 23 and made of a first material. The outer ring 22 further comprises the squirrel cage 32 made of a second material, different to the first material.

[0068] The contact portion 22-1 comprises the external surface 27 and internal surface 28, and the side walls 29. The contact portion 22-1 is made of a material having a hardness strictly greater than that of the second material. Thus, the contact portion 22-1 is made of a specific material for fulfilling the function of direct bearing support for the roller elements 23. The first material is a steel from the following list: 100C6, ASP 2060, M50, M62.

[0069] The squirrel cage 32 is made of a material having an elasticity strictly greater than that of the first material. Thus, the squirrel cage 32 is made of a specific material for withstanding loads and vibration. The second material is one out of the following list: low carbon steel, medium carbon steel, titanium alloy, aluminium alloy, M50NiL, 32CVD13, INCONEL718.

[0070] The rings 3 and 22 of the two embodiments shown in FIG. 1 are both made of two different materials. According to the invention, the rings 3 and 22 are produced by a method comprising the following steps.

[0071] The contact portion 3-1, 22-1 is machined from a bar of the first material, and has a contact surface 9, 28, respectively. The definitive dimensions and shape of the contact portion 3-1, 22-1 may be produced starting from this step.

[0072] Next, the contact portion 3-1, 22-1 thus obtained is mounted in a fixed support, in such a way that part of its outer surface is free. This outer surface part corresponds to the surface on which the fastening portion will be formed and attached in subsequent steps. Thus, the outer surface of the side wall 10 of the contact portion 3-1 is left free, and the outer surface of the side wall 29 of the contact portion 22-1 is left free. According to a particular embodiment of this method, the contact portion is mounted in a fixed support in such a way that only the surface of the side wall 10, 29 is flush with a mounting surface of the support. To this end, the contact portion 3-1, 22-1 may be housed in a recess of the support. According to a particularly advantageous embodiment, the outer surface part 10, 29 may be ground so as to be perfectly flush with the mounting surface of the support.

[0073] According to a first embodiment of the method, the contact portion 3-1, 22-1 and the support are fitted in a 3D printer. The second material is stored in powder form, and the shape of the fastening portion 3-2, 32 is printed on the contact portion 3-1, 22-1, respectively. More specifically, successive layers of the second material are deposited on the free surface of the side wall 10, 29 of the contact portion 3-1, 22-1, until the fastening portion 3-2, 22 is formed.

[0074] According to a second embodiment, a mould having the shape of the fastening portion is mounted on the contact portion 3-1, 22, in such a way that only the surface of the side wall 10, 29 on which the fastening portion will be formed is free inside the mould.

[0075] The fastening portion 3-2, 32 is formed by injecting powder into the mould, which is closed, under vacuum. The shape thus obtained is consolidated by hot isostatic pressing (HIP).

[0076] According to further embodiments, the powder of the second material may be fused by electron beam melting, selective laser melting, or by direct metal deposition.

[0077] Lastly, the dimensions of the fastening portion 3-2, 22 are finalized by machining. The method for producing the ring 3, 22 may also include a step of deposition of a surface coating, in particular on the raceways 9, 28.

[0078] Furthermore, the technical features of the different embodiments may, as a whole and only in the case of some, be combined. Thus, the ball joint may be adapted in terms of cost, performance and user-friendliness.

[0079] The present invention has been described for an articulated part in the form of a ball joint and for a bearing element, as examples of embodiments. The present invention may be used for any kind of connection element.