WO2007071099A1

WO2007071099A1 - Method of assembling a rolling bearing and rolling bearing manufactured using this method

Info

Publication number: WO2007071099A1
Application number: PCT/CH2006/000729
Authority: WO
Inventors: François HUGUELET
Original assignee: Mps Micro Precision System Ag
Priority date: 2005-12-23
Filing date: 2006-12-20
Publication date: 2007-06-28

Abstract

The invention relates to a method of assembling a ball rolling bearing and to such a ball bearing with three or four points of contact, which is characterized by the use of the extreme precision on the geometry of the ball for positioning the other constituent parts of the bearing, and to such a bearing (20), the four points of contact of which consist of four tapering surfaces (21a, 22a, 22b, 24a) bearing against pairs of opposed sides of the balls (23; 33; 43). This bearing comprises a central core (21) exhibiting one (21a) of the four tapering surfaces, an outer ring (22) exhibiting another two (22a, 22b) of the four tapering surfaces, and a clamping cone (24) exhibiting the fourth tapering surface (24). The clamping cone (24) is fixed to the core (21) by rigid means of connection such as bonding or welding when it is in the position in which the bearing runs freely without any stress and without any binding.

Description

METHOD OF ASSEMBLING A BEARING AND BEARING PRODUCED ACCORDING TO THIS METHOD

TECHNICAL FIELD The present invention relates to a method of assembling a ball bearing and more particularly to a ball bearing with three or four points of contact, these contact points being constituted by the support of conical surfaces on the sides. opposing said balls, this ball bearing having a central core, an outer ring and at least one clamping cone.

It also relates to a ball bearing and more particularly to a ball bearing with three or four contact points, these contact points being constituted by the support of conical surfaces on opposite sides of said balls, this ball bearing comprising a central core. , an outer ring and at least one clamping cone assembled according to this method.

Prior art

Ball bearings are already known, in particular of the type with four contact points frequently used in mechanical parts of small dimensions, in particular in timepieces or in medical equipment to replace the double bearings commonly used to axially position an axis. . These are miniaturized bearings, typically having diameters of the order of 0.8 to 1.6 mm, without lubrication, which do not support any blockage or even a constraint capable of slowing down or braking the rotation.

Usually, in these ball bearings, the components comprising the conical surfaces are machined with great precision, but must be assembled with play to allow free rotation, without excessive stress or blockage.

It is relatively easy to machine conical surfaces that rely on balls with a very good form accuracy and we know how to make the balls with an extremely tight tolerance of shape. Nevertheless, the addition of all these tolerances forces the ball bearing manufacturer to assemble the components with play to prevent blockage or rolling irregularities and requires a pairing of the components preceded by a tri-dimensional.

As a result, bearings of this type are assembled and tested before being put on the market and it is found that it requires a complex and meticulous assembly process.

French Patent No. 1,161,833 discloses a bearing intended for a thrust bearing which is assembled with a prestress. This type of assembly is not suitable for miniaturized bearings in general, when the assembly is conventional.

US 2002/0037123 A1 discloses a ball bearing of very large diameter used in medical equipment of the scanner type. This type of bearing having a diameter of about one meter has the same characteristics as miniaturized bearings of the order of one millimeter.

The Swiss patent CH 160 513 relates to a ball bearing in which the balls are positioned from the nut, which does not guarantee a ride without constraints and without play.

The international publication WO 03/098063 A of the same applicant relates to a ball bearing which is characterized by the nature of its balls made of zirconium oxide. The mounting mode is traditional and does not guarantee a ride without constraints and without play.

Presentation of the invention

The object of the present invention is to propose a method of assembling a ball bearing, so that the components have no play, using the very high geometric precision, that is to say, both the shape and the dimensions of the balls, to optimally position the other components of the bearing.

This object is achieved by the method as defined in the preamble and characterized in that the following successive operations are carried out: the outer ring is positioned with respect to the central core while leaving a space for the path of the balls; the balls are placed in said space of the ball path; - Provisionally places the at least one clamping cone with clearance relative to the core, so that it is supported on the balls previously placed in said space of the ball path; said clamping cone is positioned by searching for the position in which the bearing rotates freely without constraint and without blocking, and - it permanently fixes said clamping cone in this position by rigid connection means.

According to a variant, the balls are placed in said space of the ball path after the establishment of a ball cage on said core.

According to a first advantageous embodiment, said rigid connection means used to fix the cone to the core may comprise a weld. This weld is preferably a laser weld.

According to a second advantageous embodiment, said rigid connection means used to fix the cone to the core may comprise a bonding.

This object is also achieved by the bearing according to the invention as defined in the preamble and characterized in that said at least one clamping cone is fixed to the core by rigid connection means when said cone is in the position in which the bearing rotates. freely without constraint and without blocking. In a first embodiment, the central core has one of the conical surfaces, the outer ring has two other conical surfaces, and the clamping cone has a fourth conical surface.

In a second embodiment, the ball bearing according to the invention comprises a second clamping cone secured to the central core and symmetrical to the first clamping cone relative to the horizontal median plane of said bearing, said second cone having said fourth surface, conical .

In an inverted bearing variant, if said bearing is at four points of contact, the central core has two conical surfaces, the outer ring has another of the conical surfaces, and said at least one clamping cone has a fourth conical surface. If the bearing is at three points of contact, the central core has a conical surface, the outer ring has another of the conical surfaces, and the at least one clamping cone has a third conical surface.

According to a first embodiment, said cone may be fixed to said core by a weld. This weld is preferably a laser weld.

According to a second embodiment, said cone may be fixed to said core by gluing.

Brief Description of the Drawings The present invention will be better understood and its advantages will become more apparent from the following description of various embodiments illustrated by the appended drawings in which:

FIG. 1 is a view in axial section illustrating a mechanical assembly with two juxtaposed bearings arranged to stabilize the angular positioning of an axis, FIG. 2 is a view in partial axial section of a first embodiment of a bearing according to the invention,

FIG. 3A is a view in partial axial section of a second embodiment of a bearing according to the invention comprising a ball cage,

FIG. 3B is a view similar to that of FIG. 3A, but which represents an inverted bearing,

FIG. 3C is an alternative embodiment of the inverted bearing of FIG. 3B,

FIG. 4 is a view in partial axial section of a third embodiment of a bearing according to the invention, comprising a ball cage;

FIG. 5 is a partial sectional view illustrating the fixing means by welding the core and the cone, and

Figure 6 is a partial sectional view illustrating the fixing means by bonding the core and the cone.

Way (s) to realize the invention

FIG. 1 represents a miniaturized ball bearing 10 consisting essentially of an axle 11 mounted on a support 12 via two ball bearings 13 and 14 juxtaposed. This arrangement with two ball bearings 13 and 14 juxtaposed is used to ensure the axial stability of the assembly 10. The two ball bearings 13 and 14 respectively comprise an inner ring 13a and 14a, an outer ring 13b and 14b and balls. 13c and 14c. The inner rings 13a and 14a as well as the outer rings 13b and 14b comprise precisely ground raceways which define the bearing surfaces of the balls 13c and 14c.

The invention relates to a ball bearing, in particular of the four-point type contact, these four contact points being constituted by the support of four conical surfaces on two sides opposite sides of said balls. This type of ball bearing makes it possible to guarantee, alone and not in combination with another juxtaposed ball bearing, the axial stability of a mechanical assembly. Therefore, it allows a reduction in size and is particularly well suited, but not exclusively, to miniaturization, for example in the field of watchmaking or medical equipment.

FIG. 2 shows a miniaturized ball bearing, also at four points of contact, which typically has a diameter of the order of one millimeter and which is particularly intended for a watch application. This ball bearing 20 comprises a central core 21, an outer ring 22, a ring of balls 23 and a clamping cone 24. The central core 21 is machined to comprise a conical surface 21a, defining one of the four points of contact of the balls. 23. This conical surface 21a is disposed at an angle of 45 ^e relative to the axis of the ball bearing 20. The outer ring 22 is machined to comprise two conical surfaces 22a and 22b respectively which define two other points of contact of the balls. 23. These two conical surfaces 22a and 22b are arranged at a certain angle, preferably an angle of 45 °, with respect to the axis of the ball bearing 20 and form between them a substantially straight angle. The clamping cone 24 is machined to have a conical surface 24a, defining the last of the four points of contact of the balls 23. This conical surface 24a is disposed at an angle of 45 ° with respect to the axis of the ball bearing 20. Note that the balls are preferably ceramic balls

The manner of assembly of this bearing 20 as well as that of the other embodiments illustrated in FIGS. 3A, 3B and 4 will be described in detail below.

Figure 3A shows a ball bearing 30 with four contact points according to the invention. This ball bearing 30 comprises, like the bearing 20 of the previous figure, a central core 31, an outer ring 32, a ring of balls 33 and a clamping cone 34. It further comprises a ball cage 35 which is mounted on the central core 31. The conical surfaces 31a, 32a, 32b and 34a are similar to the respective conical surfaces 21a, 22a, 22b and 24a of the ball bearing shown in Figure 2. The balls 33 spaced apart in the ball cage 35 serve to support the four abovementioned contact surfaces.

FIG. 3B shows an inverted four-contact ball bearing 130, which has the same components as the bearing 30, but where these components are arranged in a reverse manner. In this bearing 130, the outer ring 132 has the shape and the central core position 31 of the bearing 30 and defines a point of contact 132a. The central core 131 has the shape and the position of the outer ring 32 of the bearing 30 and defines two points of contact 131a and 131b, symmetrical with respect to the transverse median plane of the balls, for said balls 133. The cone 134 is outer relative 133, which may optionally be housed in a cage 135, and cooperates with the outer ring 132 to define the fourth point of contact 134a.

FIG. 3C illustrates a variant of the ball bearing 130 of FIG. 3B in which the balls 133 'have only three points of contact. In this bearing 130 'the central core 131 of the bearing 130 defining two points of contact for the balls 133' is replaced by a core 131 'provided with a semicylindrical groove whose radius of curvature is greater than that of the balls 133' so as to define only a single point of contact 131'c of said beads. This point of contact 131 'c is thus disposed in the horizontal median plane of the balls 133'. The other components of this bearing 130 'are identical to those of the bearing 130 and define the other two points of contact 132'a and 134'a of the balls 133'.

FIG. 4 represents a ball bearing 40 with four contact points according to the invention. This ball bearing 40 comprises, like the bearing 30 of the previous figure, a central core 41, an outer ring 42, a ring of balls 43 but two clamping cones 44a and 44b integral with the core 41 and arranged symmetrically with respect to the horizontal median plane of said bearing 40. These cones are respectively provided with recesses 45a and 45b opposite in which is housed a ball cage 45c. The two clamping cones 44a and 44b are in a way an inner ring opposite the outer ring 42 and cooperating with the latter to trap the balls 43 in the space that these two rings delimit. As before, the balls bear on two-by-two orthogonal contact surfaces 42a, 42b, 44aa and 44bb, the conical surface formed on the central core being in this case replaced by the conical surface 44bb formed on the second clamping cone 44b. .

According to the assembly method of the invention, the operations for mounting the ball bearings described above, in particular the ball bearing 20 illustrated in FIG. 2, are as follows. Positioning, for example on a mounting template, not shown, the outer ring 22 relative to the central core 21 by leaving the space of the ball path in which the beads 23 are placed in place. It will be noted that the bounded space between the outer ring 22 and the central core 21 allows the insertion of the balls 23 so that they are supported on the three contact surfaces 21a, 22a and 22b. Since the manufacture of the balls can be extremely precise, in principle much more precise than that of the conical contact surfaces, when all the balls are in place, it is possible to position the clamping cone 24 with reference to the support on the balls. 23. The cone 24 is provided to have clearance with respect to the central core 21 so that its final position is not imposed by the geometry of the central bore of the outer ring 22 nor by that of the corresponding surface of the central core 21, but by that of the series of balls 23. In practice, the operator rotates the clamping cone 24 on the balls until it finds the right position, that is to say that in which the outer ring 22 rotates freely without mechanical stress. When the free rolling position is identified, regardless of the degree of "centering" or "off-centering" between the central core 21 and the outer race 22, the operator remains free to freeze this position by appropriate means. . By way of example, FIG. 5 shows a ball bearing according to the invention, such as the ball bearing 20 in which the clamping cone 24 is locked in its proper position relative to the central core 21 by a weld bead. 51. This weld is preferably made by laser. It can in fact be any suitable weld, especially a spot weld performed at different points of the periphery of the central bore of the clamping cone 24.

By way of example also, Figure 6 shows a ball bearing according to the invention, such as the ball bearing 20 in which the clamping cone 24 is locked in its proper position relative to the central core 21 by gluing. A net of glue 61, preferably fast setting, is applied in the space between the core 21 and the clamping cone 24. This glue net 61 can fill the space partially or completely. Its purpose is to freeze the relative position of the cone 24 and the central core 21 when the correct positioning, that is to say that which allows an unrestrained operation of the ball bearing 20, is achieved.

It is obvious that the two modes of attachment as described with reference to Figures 5 and 6 also apply to other ball bearings according to the invention, including ball bearings 30 and 40.

The present invention fulfills its purpose and makes it possible to manufacture in a simple manner bearings with three or four contact points without clearance. Although the machining of the clamping cone is initially done with play, the selective positioning of this cone of tightening and its final fixing in the selected position, makes it possible to obtain a ball bearing without play.

Claims

1. A method of assembling a ball bearing and more particularly a ball bearing with three or four contact points, these contact points being constituted by the support of conical surfaces on opposite sides of said balls, this ball bearing comprising a central core, an outer ring and at least one clamping cone, characterized in that the following successive operations are carried out: the outer ring is positioned with respect to the central core while leaving space for the path of the beads; the balls are placed in said space of the ball path; provisionally places the at least one clamping cone with play relative to the core, so that it is supported on the balls previously placed in said space of the ball path; said clamping cone is positioned by searching for the position in which the bearing rotates freely without constraint and without locking, and the clamping cone is permanently fixed in this position by rigid connection means.

2. A method of assembling a ball bearing according to claim 1, characterized in that said beads are put in place after the prior establishment of a ball cage.

3. A method of assembling a ball bearing according to claim 1, characterized in that said rigid connecting means used for fixing the cone to the core comprise a weld.

4. A method of assembling a ball bearing according to claim 3, characterized in that said weld is a laser weld.

5. A method of assembling a ball bearing according to claim 1, characterized in that said rigid connection means used to fix the cone at the core include a collage.

6. Ball bearing with three or four points of contact (20; 30; 130; 130 '; 40), these contact points being constituted by the support of conical surfaces on opposite sides of said balls (23; 33; 133 ; 133 ': 43), this ball bearing comprising a central core (21; 31; 131; 131'; 41), an outer ring (22; 32; 132; 132 '; 42), and at least one cone of clamping device (24; 34; 134; 134 '; 44a) assembled according to the method of any one of claims 1 to 5, characterized in that said at least one clamping cone (24; 34; 134; 134'; 44a); ) is fixed to the core (21; 31; 131; 131 '; 41) by rigid connection means when said cone is in the position in which the bearing rotates freely without constraint and without locking on the balls.

7. Ball bearing according to claim 6, characterized in that the central core (21; 31) has one of the conical surfaces (21a; 31a), the outer ring (22; 32) has two others (22a, 22b; 32a). , 32b) conical surfaces, and said at least one clamping cone (24; 34) has a fourth conical surface (44a).

Ball bearing according to Claim 6, characterized in that the central core (131) has two conical surfaces (131a, 131b), the outer ring (132) has another (132a) conical surfaces, and the at least one a clamping cone (134) has a fourth conical surface (134a).

9. A ball bearing according to claim 6, characterized in that the central core (131 ') has a conical surface (131' c), the outer ring (132 ') has another (132'a) conical surfaces, and said at least one clamping cone (134 ') has a third conical surface (134'a).

Ball bearing according to Claim 7, characterized in that comprises a second clamping cone (44b) integral with the central core (41) and symmetrical with the first clamping cone (44a) with respect to the horizontal median plane of said bearing (40), said second cone (44b) having the fourth conical surface ( 44b).

11. Ball bearing according to claim 6, characterized in that said clamping cone (24) is fixed to said core by a weld (51).

12. Ball bearing according to claim 11, characterized in that said weld (51) is a laser weld.

13. Ball bearing according to claim 6, characterized in that said clamping cone (24) is fixed to said core by gluing (61).