FR2751709A1 - Roller bearing unit with conical rollers for circular shaft for machine tools - Google Patents

Abstract

The unit (10) consisting of a bearing of conical rollers (11) provided with an interior conical ring (12) designed to be connected to a fixed or turning shaft (21,61,81), of an exterior conical ring (13) arranged to be coupled to a turning or fixed bearing (22,62,82) and a series of conical rollers (14) fitted between the interior and exterior rings. The rollers are contained by a cage (15). The unit further contains an axial stop (16) on which the rollers act to oppose the reaction force of the axial component of the loads to the rollers by the shaft and/or the bearing. The axial stop (16) is made up of a support element (30,40,50,70,90) independent of the interior (12) and exterior (13) rings, this support element being coupled in rotation with the rollers (14) in a manner to limit the lateral friction of the rollers.

Description

CONDUCTED ROLLER BEARING DEVICE
The present invention relates to a rolling device comprising at least one tapered roller bearing provided with a conical inner ring intended to be coupled to a fixed or rotating shaft, a conical outer ring intended to be coupled to a rotating bearing or to a fixed housing, also called a bearing, and at least one row of tapered rollers provided between the inner and outer rings, said rollers being held by a cage, this device further comprising means of axial abutment of said rollers arranged to oppose a reaction force to the axial component of the loads transmitted to said roller bearing by the shaft and / or the bearing.

The use of tapered roller bearings is well known. These bearings are generally suitable for assemblies in which the radial and axial loads are significant, but in which the rotational speeds are limited. This type of bearing is not suitable for high rotation frequencies, such as for example a spindle of machine tools. Indeed, the rollers are carried by conical rings and when they are subjected to a radial load, they automatically generate an axial load which tends to drive them out of said rings. To avoid this phenomenon, an axial stop is provided and generally consists of a shoulder secured to one of the inner or outer rings, this shoulder being commonly called large shoulder. as a result, at each point in the contact zone of a roller on the large shoulder of the inner ring, for example, friction is created along segments of curves. This friction generates heat production, rolling resistance of the tapered rollers, loss of power and wear. On the other hand, the radial and axial loads generate a force which causes the rolling of the rollers around the axis of this rolling. Consequently, the resistance due to the friction between the rollers and the large shoulder and the force which causes the displacement of the rollers create a torque which tends to disturb the alignment of said rollers. These drawbacks arise from the fact that the angular displacement of the large shoulder integral with the inner ring necessarily depends on the number of turns of the latter. This is also verified in the case where the large shoulder is provided on the outer ring.

The object of the present invention is to overcome the drawbacks mentioned above and to allow the simple and inexpensive production of a self-supporting rolling device, in addition to the significant radial loads, high rotation frequencies for a near minimum operating clearance. from zero.

This object is achieved by a rolling device as defined in the preamble, characterized in that the axial stop means comprise a support element independent of the inner or outer rings and in that this support element is coupled in rotation with said tapered rollers, so as to limit the lateral friction of said tapered rollers.

In this embodiment, the rollers then control the angular displacement of the support element. Only sliding friction results from a difference in speed of the contact points arranged on the same generator between the roller and the element d 'support. The value of this resistance due to sliding is very small since the distance between two contact points is also low.

In a preferred embodiment of the invention, the abutment means comprise a separate bearing bearing disposed adjacent to said roller bearing, this bearing bearing comprising an inner ring secured to Marble, a free outer ring and members of bearing provided between said inner and outer rings, the outer ring of this support bearing being arranged to constitute said support element for said rollers.

Advantageously, the outer ring is extended laterally in the direction of said rollers by a chamfered profile providing said rollers with a bearing surface of limited extent, this bearing surface being arranged optionally near the inner ring or the outer ring of said roller bearing.

The device according to the invention can comprise two inverted roller bearings oriented in an arrangement called "X". In this case, the axial stop means are common to said two bearings and comprise a separate support bearing disposed adjacent to said two bearings, the free outer ring of said support bearing being arranged to constitute said support element for said rollers of each bearing.

The device according to the invention can also include two inverted roller bearings oriented in an arrangement called "O". In this case, the axial stop means associated with each bearing are independent and each comprise a separate support bearing disposed adjacent to the outside of said roller bearings, the free outer ring of each support bearing being arranged to constitute said support element for said rollers of the corresponding roller bearing.

In an alternative embodiment of the invention, the stop means comprise a separate bearing bearing disposed adjacent to said roller bearing, this bearing bearing comprising an outer ring integral with the bearing, a free inner ring and members bearing provided between said inner and outer rings, the inner ring of this support bearing being arranged to constitute said support element for said rollers.

The inner ring is then advantageously extended laterally in the direction of said rollers by a chamfered profile providing said rollers with a bearing surface of limited extent, this bearing surface being arranged as desired near the outer ring or the inner ring of said roller bearing.

In the context of this variant, the device according to the invention may include two inverted roller bearings oriented in an arrangement called "X". The axial stop means are, in this case, common to said two bearings and comprise a separate support bearing disposed adjacent to said two bearings, the free inner ring of said support bearing being arranged to constitute said support element for said rollers of each bearing.

This device can also include two inverted roller bearings oriented in an arrangement called "O". In this case, the axial stop means associated with each bearing are independent and each comprise a separate support bearing disposed adjacent to the outside of said roller bearings, the free inner ring of each support bearing being arranged to constitute said support element for said rollers of the corresponding roller bearing.

The separate support bearing provided in the device according to the invention may consist of a radial contact ball bearing, an angular contact ball bearing, a ball bearing or any other suitable bearing.

The present invention and its advantages will appear better in the following description of several non-exhaustive exemplary embodiments, with reference to the appended drawings, in which: FIGS. 1 to 5 successively show five different embodiments of the rolling device according to the invention.

Referring to Figure 1, the rolling device 10 according to the present invention is provided in an assembly 20 of a shaft 21 guided in bearings 22. Figure 1 shows only a rolling device while this type of assembly requires at least two rolling devices to ensure good guiding in rotation of the shaft or the bearing while ensuring a distribution of the radial loads. The shaft 21 can be rotating and the bearing 22 fixed or vice versa. In this case, we commonly speak of a rotating housing also called in the text "landing". The rolling device 10 comprises a tapered roller bearing 1 1 provided with a conical inner ring 12, called a cone, mounted on the shaft 21, a conical outer ring 13, called a cup, mounted in the bearing 22, at at least one row of conical rollers 14 provided between the two rings 12, 13, the rollers being held by a cage 15.

This bearing 11 is axially prestressed by compression springs 23 acting on the outer ring 13. The bearing device 10 comprises axial stop means 16 formed by a support element independent of the inner 12 and outer 13 rings, free in rotation and against which support the rollers 14 which drive it in rotation.

These stop means 16 comprise a ball bearing 30 mounted adjacent to said roller bearing 11. This ball bearing 30 comprises an inner ring 31 mounted on the shaft 21, a free outer ring 32 and a row of balls 33 provided between the two rings 31, 32, the balls being held by a cage 34. This ball bearing 30 is in oblique contact, that is to say that the balls 33 are guided in off-axis raceways provided respectively on the rings 31 , 32. The outer ring 32 constitutes the support element of these stop means 16. It extends laterally in the direction of the rollers 14 by a chamfered profile to provide a limited support surface 32 '. In the figures, this bearing surface 32 'is positioned near the inner ring 12 of the bearing 11 in order to reduce the circumference of this bearing surface as much as possible.

However, it can advantageously be provided near the outer ring 13 of said bearing 11, if the inner ring 31 has a larger outer diameter. In this position, the bearing surface 32 ′ benefits from automatic lubrication by the grease from the bearing 11 which is discharged upwards by the tapered rollers, the taper producing a pumping effect.

In assembly 20, the inner rings 12, 31 of the corresponding bearings 11, 30 are locked on the shaft 21 between a shoulder 24 provided on this shaft against which the ring 12 rests and a nut 25 screwed into a thread provided on the corresponding end of the shaft, which presses on the ring 31. The rolling device 10 is prestressed by means of compression springs 23 bearing on a flange 26 integral with the bearing 22. These springs 23 act on the outer ring 13 of the bearing with rollers in housings 13 'provided for this purpose and forming guide frits for the springs. The outer ring 13 transmits the axial force of the springs 23 to the rollers 14, which is transformed into an axial component and a radial component. The axial component tends to push the rollers 14 against the free outer ring 32 of the ball bearing 30. The position of this outer ring 32 is balanced by the counter thrust exerted by the nut 25 on the corresponding inner ring 31. The presence of the springs 23 ensures automatic backlash, in particular in the event of wear of the rollers or of the corresponding rings. During the rotation of the shaft 21, the inner rings 12, 31 are driven simultaneously. The rollers 14 then rotate on themselves and around the axis of said bearing 11, driving with them by fiction the free outer ring 32 of the ball bearing 30. Thus, there remains between the rollers 14 and the bearing surface 32 ′ that a slight friction due to the sliding coming from the differences in circumferential speed of the contact points arranged on the same generator.

The other FIGS. 2 to 5 illustrate alternative embodiments of the rolling device 10 according to the present invention, in which the parts similar to those of FIG. 1 have the same reference numbers.

In FIG. 2, there is a substantially identical assembly 20 in which the rolling device 10 comprises axial stop means 16 consisting of a ball bearing 40 with radiaL contact This ball bearing 40 comprises an inner ring 41 secured to the 'shaft 21, a free outer ring 42 and a row of balls 43 provided between the two rings 41, 42, the balls being held by a cage 44. The outer ring 42 constitutes the support element of the stop means and is extends radially towards the rollers 14 of the bearing 11 by a chamfered profile to provide a limited bearing surface 42 ', as in the previous example. In order to position the bearing surface 42 'near the inner ring 12 of the roller bearing 11, the inner ring 41 of the ball bearing 40 is mounted on a shoulder 27 with a diameter smaller than that which carries the inner ring 12. Nevertheless and as explained above, this bearing surface 42 ′ can be arranged near the outer ring 13. In this case, it is no longer necessary to provide the shoulder 27. As in the previous example , the inner rings 12, 41 of the corresponding bearings are locked between the shoulder 24 and the nut 25 and the device 10 is prestressed by the springs 23.

In FIG. 3, the same configuration is found as in FIGS. 1 and 2. The axial stop means 16 comprise a ball stop 50 provided with a stop ring 51 integral with rarbre 21, a free ring 52 and a row of balls 53 disposed between the two rings 51, 52, the balls being held by a cage 54. The free ring 52 is extended laterally in the direction of the rollers 14 by a chamfered profile offering a bearing surface 52 'limited and located close of the inner ring 12 of the bearing 11. The inner rings 12, 51 are locked between the shoulder 24 and the nut 25. A spacer 55 is provided between the two inner rings 12, 51 to ensure the correct positioning of the stopper. balls 50 and its operating clearance.

FIG. 4 illustrates a particular arrangement 60 between a shaft 61 and a bearing 62 in which there are provided two inverted rolling devices 10 arranged at "X". This type of "X" mounting means that the bearings 11 are oriented in such a way that the direction of the loads applied to the rollers 14 of each of the bearings 11 converges. This arrangement is generally used in the case of a rotating shaft. In this configuration, the stop means 16 are advantageously common to the two devices 10 and are provided between the two roller bearings 11. They comprise a ball bearing 70 with radial contact provided with an inner ring 71 integral with the shaft 61 , a free outer ring 72 and a row of balls 73, the balls being held by a cage 74. The free outer ring 72 constitutes the bearing element of the stop means 16 for the rollers 14 of the bearings 11 This outer ring 72 is extended laterally in the direction of these rollers 14 by a chamfered profile, provided on each side of said ring, and offering a bearing surface 72 'limited respectively to each row of rollers 14. The inner rings 12 of roller bearings 1 1 and that 71 of the ball bearing 70 are locked on the shaft 61 between a shoulder 64, a spacer 65 and a nut 66 provided at the corresponding end of the shaft 61. L es devices 10 are prestressed respectively by springs 63 acting between a flange 67, 68 and the corresponding outer ring 13 of the bearings 11. During the rotation of the shaft 61, the inner rings 12, 71 rotate simultaneously, driving with them the conical rollers 14 which simultaneously drive the outer ring 72 of the ball bearing 70.

FIG. 5 illustrates an alternative assembly 80 of FIG. 4 in which the rolling devices 10 are arranged in "O" shape. This type of "O" mounting means that the bearings 1 1 are oriented in such a way that the direction of the loads applied to the tapered rollers 14 of each of the bearings 1 1 diverges. This arrangement is generally used in the case of a rotary bearing 82. In this configuration, each device 10 has its own stop means 16 consequently arranged outside the "O" arrangement. These stop means 16 comprise ball stops 90 provided with a stop ring 91 secured to the shaft 81, a free ring 92 coupled in rotation with the corresponding rollers 14 by a bearing surface 92 'and d 'A row of balls 93 provided between the two rings 91, 92, the balls being held by a cage 94. In this assembly 80, the inner rings 12, 91 are mounted integrally on the shaft 81 and are locked between a shoulder 84 of the shaft and a nut 85 provided at the corresponding end of the shaft 81. A spacer 86 is arranged between the inner rings 12 of the two bearings 11 and as previously a spacer 87 ensures the positioning and the operating clearance between the inner rings 12 and 91 of each device 10. The rolling devices 10 are prestressed by means of compression springs 83 provided between the two outer rings 13 of the roller bearings 11.

 it emerges from this description that the device of the invention achieves the goals set, namely to significantly limit the rolling resistance in tapered roller bearings so that they can be used for high rotation frequencies. The principle used can be extended to other arrangements or configurations. The bearing surface of the stop means on the rollers can be arranged either near the inner ring, or near the outer ring of the tapered roller bearing. Furthermore, the stop means can be associated with the outer ring of the tapered roller bearing. In this case, it is the inner ring of the separate bearing which is free and serves as a support element for the tapered rollers. Likewise, these axial stop means may also include other types of bearings. The definition of the type of bearing depends on the mechanical constraints, the loads, the rotational speeds and the type of assembly. On the other hand, the preload springs can be replaced or combined by any other means, in particular by a variable preload device controlled by hydraulic or pneumatic pressure.

The present invention is therefore not limited to the embodiments described, but extends to any modification and variant obvious to a person skilled in the art, while remaining within the protective field defined by the appended claims.

Claims (14)

Claims 1. Rolling device (10) comprising at least one tapered roller bearing (11), provided * a conical inner ring (12) intended to be coupled to a fixed or rotating shaft (21,61,81), * a ring conical outer (13) arranged to be coupled to a rotating or fixed bearing (22,62,82) and at least one row of conical rollers (14) provided between the inner and outer rings, said rollers being held by a cage (15), this device comprising in addition axial stop means (16) of said rollers arranged to oppose a reaction force to the axial component of the loads transmitted to said bearing by the shaft and / or the bearing, characterized in that the axial stop means (16) comprise a support element (30,40,50,70,90) independent of the inner (12) and outer (13) rings and in that this support element is coupled in rotation with said rollers (14), so as to limit the lateral fiction of said rollers ux. 2. Device according to claim 1, characterized in that the stop means (16) comprise a separate bearing bearing (30,40,50,70,90) disposed adjacent to said roller bearing (11), this support bearing comprising an inner ring (31,41,51,71,91) integral with the shaft (21,61,81), a free outer ring (32,42,52,72,92) and organs bearing (33,43,53,73,93) provided between said inner and outer rings, the outer ring of this support bearing being arranged to constitute said support element for said rollers (14). 3. Device according to claim 2, characterized in that the outer ring (32,42,52,72,92) is extended laterally towards said rollers (14) by a chamfered profile providing said rollers (14) with a surface of support (32 ', 42', 52 ', 72', 92 ') of limited extent. 4. Device according to claim 3, characterized in that said bearing surface (32 ', 42', 52 ', 72', 92 ') is optionally arranged near the inner ring (12) or the ring outside (13) of said roller bearing (11). 5. Device according to claim 4, characterized in that it comprises two roller bearings (11) reversed and oriented in an arrangement called in that the axial stop means (16) are common to said two bearings and in that these axial stop means comprise a separate bearing bearing (70) disposed adjacent to said two bearings (11), the free outer ring (72) of said bearing bearing being arranged to constitute said bearing element for said rollers (14) of each bearing. 6. Device according to claim 4, characterized in that it comprises two roller bearings (11) inverted and oriented in an arrangement called "O", in that the axial stop means (16) associated with each bearing are independent and in that these axial stop means each comprise a separate support bearing (90) disposed adjacent to the outside of said roller bearings, the free outer ring (92) of each support bearing being arranged to constitute said support element for said rollers (14) of the corresponding roller bearing (11). 7. Device according to claim 1, characterized in that the stop means (16) comprise a separate bearing bearing disposed adjacent to said roller bearing (11), this bearing bearing comprising an outer ring integral with the bearing (22), a free inner ring and rolling members provided between said inner and outer rings, the inner ring of this support bearing being arranged to constitute said support element for said rollers (14). 8. Device according to claim 7, characterized in that the inner ring is extended laterally towards said rollers (14) by a chamfered profile offering said rollers (14) a bearing surface of limited extent. 9. Device according to claim 8, characterized in that said bearing surface is arranged as desired near the outer ring (13) or the inner ring (12) of said roller bearing (11). 10. Device according to claim 9, characterized in that it comprises two roller bearings (11) reversed and oriented in an arrangement called in that the axial stop means (16) are common to said two bearings and in that these axial stop means (16) comprise a separate bearing bearing disposed adjacent to said two bearings (11), the free inner ring of said bearing bearing being arranged to constitute said bearing element for said rollers (14 ) of each bearing (11). 11. Device according to claim 9, characterized in that it comprises two roller bearings (11) inverted and oriented in an arrangement called "O", in that the axial stop means (16) associated with each bearing are independent and in that these axial stop means each comprise a separate support bearing disposed adjacent to the outside of said roller bearings (11), the free inner ring of each support bearing being arranged to constitute said element support for said rollers (14) of the corresponding roller bearing (11). 12. Device according to any one of claims 2 to 11, characterized in that the separate support bearing consists of a radial contact ball bearing (40,70). 13. Device according to any one of claims 2 to 11, characterized in that the bearing * separate support consists of a ball bearing with oblique contact (30). 14. Device according to any one of claims 2 to 4, 6 to 9 and 11, characterized in that the separate bearing support consists of a ball bearing (50.90).