Roller bearing with modular shoulders

A rolling bearing is provided that includes an outer ring, an inner ring, and a plurality of rollers disposed between the outer and inner rings to engage a radially outer lateral surface of the inner ring and a radially inner lateral surface of the outer ring and being laterally held, in a direction parallel to a relative rotation axis (A) between the rings, by respective axial shoulders. The axial shoulders each consist of an annular element made of synthetic plastic material as an independent element from the rings that engages in a snapping manner either the inner ring or the outer ring; the inner and outer rings being provided, at their respective radially outer and inner lateral surfaces and at opposite axial ends thereof, with snapping locking seats for the annular elements made of synthetic plastic material each including a continuous annular groove.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a rolling bearing of the roller type, which is cost-effective to be manufactured and which allows to reduce the friction between the revolving bodies, defined by rollers, generally of the cylindrical type, and the radially inner and outer rings of the bearing.

TECHNICAL BACKGROUND

In rolling bearings of the roller type, the revolving bodies, generally consisting of cylindrical rollers, are laterally held in axial direction and towards opposite frontal ends of the inner and outer rings of the bearing, by respective shoulders obtained by mechanical machining directly on the radially inner and radially outer surfaces of the rings, on which the rollers roll in use.

Therefore, according to this solution, the lateral axial holding shoulders of the rollers form an integral part of the rolling tracks of the rollers.

This solution has the drawback of requiring high-precision mechanical machining with narrow tolerances, which are therefore very costly, in order to obtain the shoulders.

Furthermore, the rollers touch the shoulders because of possible axial movements of the rollers themselves, thus producing a relatively high increase of the friction between rollers and rings, with a consequent undesired heating of the bearing and undesired energy losses.

It is the object of the present invention to provide a rolling bearing of the roller type, which is simple and cost-effective to be constructed while ensuring a perfect lateral guiding of the rollers and which simultaneously has lower friction levels than those of the roller bearings currently in use.

SUMMARY OF THE INVENTION

According to the invention, a rolling bearing of the roller type is thus provided, having the features set forth in the appended claims.

By virtue of the invention, the rollers may be guided in axial direction, both mono- and bilaterally, and both on the inner ring and on the outer ring of the bearing, regardless of the presence of a revolving body cage, which must be absent in the bearings of the full-complement roller type.

Moreover, the same inner and outer rings may be used for bearings having different shoulder configurations according to the various operative needs, thus allowing considerable economies of scale.

Finally, the contact friction between revolving bodies and lateral shoulders of the bearing rings is considerably reduced due to both the type of materials used and because pockets for containing lubricating fluids may be provided on the side of the shoulders facing the inner bearing.

DETAILED DESCRIPTION

With reference toFIGS. 1 and 3 to 7, reference numeral1indicates as a whole a rolling bearing of the roller type, comprising a radially outer ring2, a radially inner ring3and a plurality of revolving bodies defined by rollers4interposed between the radially outer ring2and the radially inner ring3and grouped, in the non-limiting example shown, into a crown of revolving bodies. Obviously, the following description may also apply to bearings with two crowns of rollers.

Rollers4engage a radially outer lateral surface5of the inner ring3and a radially inner lateral surface6of the outer ring2facing each other and laterally held, in a direction parallel to a relative rotation axis A (shown not in scale in the accompanying figures for simplicity) between the inner3and outer4rings, by respective axial shoulders7integrally carried by either one or both the inner and outer rings3and2; in the example shown, there are four shoulders7, two being integrally carried by the outer ring2and two being integrally carried by the inner ring3.

According to an aspect of the invention, the axial shoulders7each consist of an annular element8or9made of synthetic plastic material as an independent element from the outer2and inner3rings and which engages in a snapping manner either the inner ring3or the outer ring2so as to be axially integral with such a ring2,3.

In combination, the inner3and outer2rings are each provided, at the respective radially outer5and inner6lateral surfaces and at least at respective opposite axial ends10,11of the outer ring2and12,13of the inner ring3, with respective locking seats14b,c, each adapted to receive in a snapping manner a respective annular element8or9made of synthetic plastic material.

According to an aspect of the invention, each seat14b,ccomprises at least one continuous annular groove15. Two grooves15are obtained on the outer ring2, facing the inner ring3, and two grooves15are obtained on the inner ring3, facing the outer ring2.

In particular, the radially outer ring2is indeed provided with at least two opposite first locking seats14bobtained at the opposite axial ends10,11and each comprising an annular end portion16of the radially inner lateral surface6of the outer ring2, in addition to a respective annular groove15. The annular end portions16are thus arranged at the ends10,11and are flared so as to make the outer ring2thinner (i.e. to reduce its radial thickness) towards the axial ends10,11thereof.

The respective continuous annular groove15of each first seat14bis further obtained on the corresponding flared, annular end portion16of the seat14bitself, substantially on the middle line. The flared end surface16delimiting each seat14bis defined by an oblique surface with respect to axis A, in particular is defined by a stretch of a rounded conical surface, having its conicity (i.e. the opening angle) facing the rollers4.

The radially inner ring3is instead provided with at least two opposite second locking seats14cobtained at the opposite axial ends12,13of the inner ring3and each comprising an annular end portion17of the radially outer lateral surface5of the inner ring3, in addition to a respective annular groove15. The annular end portions17are thus arranged at the ends12,13and are flared so as to make the inner ring3thinner (i.e. to reduce its radial thickness) towards the axial ends12,13thereof.

The respective continuous annular groove15of each second seat14cis further obtained on the corresponding flared annular end portion17of the seat14citself, substantially on the middle line. The flared surface end portion17delimiting each seat14cis defined by an oblique surface with respect to axis A, in particular is defined by a stretch of a rounded conical surface having its conicity facing the side opposite to that of the corresponding surface portion16of the seat14b, which it faces.

Finally, the continuous annular groove15of each locking seat14b,cis made so as to have a rounded saw-tooth profile in radial section such that groove15has a maximum radial depth in a vicinal position with respect to the respective axial ring end10,11,12,13adjacent thereto, and thus on the side opposite to the conicity of the surface portion16or17on which groove15is obtained.

According to a feature of the invention, bearing1comprises at least a first annular element8made of synthetic plastic material which couples to the radially outer ring2and at least a second annular element9made of synthetic plastic material, which couples to the radially inner ring3, on the side opposite to the annular element8, for example, the annular element8being in a corresponding seat14band the annular element9being in a corresponding seat14c, respectively.

In the non-limiting example shown, bearing1is provided with two annular elements8band8cwhich couple to the outer ring2, at the opposite ends10,11and in seats14b, and with two annular elements9band9c, which couple to the inner ring3, at the opposite ends12,13and in seats14c.

The annular elements8b,care shaped so as to be mirror-wise symmetric to each other; similarly, the annular elements9b,care shaped so as to be mirror-wise symmetric to each other.

Each annular element8b,cand9b,c(only the annular element9bis shown in detail inFIGS. 4 and 5for simplicity, while only the annular element8bis shown in detail inFIGS. 6,7for simplicity) is formed by molding in a single piece and comprises first circumferential sectors18and second circumferential sectors19, arranged mutually alternating and integrally obtained in one piece with one another.

The first circumferential sectors18of the annular elements8b,care solid radial sectors, stiffer than the second sectors19of the annular elements8b,c, and are radially delimited on the outside by a radially outer lateral surface20of the annular element8b,cwhich mimics an axial annular profile of the locking seat14bof end10for the annular element8band of the locking seat14bof end11for the annular element8c, so that the surface20of each annular element is also flared and defined by a stretch of a rounded conical surface having its conicity facing rollers4, so as to couple in contact with the annular profile of the first seat14bof the outer ring2which receives each element8b,c.

The second circumferential sectors19of the annular elements8b,care instead each provided with a circumferential indentation21having a depth directed in axial direction and obtained on an axially outer front surface22of the annular element8b,c, facing the opposite side of rollers4. Each indentation is U-shaped on the axially outer front surface22(i.e. when observed looking towards the front surface22) and detaches on the annular element8b,8ca circumferential wing23, elastically deformable in radial direction and which overhangingly extends radially on the outside of the annular element8b,c.

Each wing23is delimited radially on the outside by the radially outer lateral surface20of the annular element8b,c(which therefore couples to the corresponding seat14b); the side surface20is however partially interrupted by indentation21at each sector19and towards the opposite ends of each second sector19.

Furthermore, according to an aspect of the invention, each wing23is provided at the radially outer lateral surface20of the annular element8b,cwith a radial tooth24which couples within the continuous annular groove15of the locking seat14bof the end10or11engaged by the respective annular element8bor8c; indeed, each tooth24has a circumferential, axial profile which mimics that of the continuous annular groove15and radially overhangingly protrudes from the lateral surface20(FIG. 7), so as to engage groove15in a snapping manner when the annular element8b,cis pushed into the respective seat14b, while the lateral surface20couples fit to the annular surface portion16.

The first circumferential sectors18of the annular elements9b,care also solid radial sectors, stiffer than the second sectors19, of the annular elements9b,cand are radially delimited on the inside by a radially inner lateral surface25of the annular element9b,cwhich mimics an axial annular profile of the locking seat14cof end12for the annular element9band of the locking seat14cof end13for the annular element9c, so that the surface25of each annular element9b,cis also flared and defined by a stretch of a rounded conical surface having its conicity facing the opposite side of rollers4, so as to couple in contact with the axial annular profile of the second seat14cof the inner ring3which receives each element9b,c.

The second circumferential sectors19of the annular elements9b,care each provided, as their corresponding annular elements8b,c, with a circumferential indentation26having a depth directed in axial direction and obtained on an axially outer front surface27of the annular element9b,c, facing the opposite side of rollers4. Each indentation26is U-shaped on the axially outer front surface27(i.e. when observed looking towards the front surface27) and detaches on the annular element9b,9ca circumferential wing28, elastically deformable in radial direction and which radially overhangingly extends radially on the inside of the annular element9b,c.

Each wing28is delimited radially on the inside by the radially inner lateral surface25of the annular element9b,c(which therefore couples to the corresponding seat14c); the lateral surface25is however partially interrupted by indentation26at each sector19and towards the opposite ends of each second sector19.

Moreover, according to an aspect of the invention, each wing28is provided at the radially inner lateral surface25of the annular element9b,cwith a radial tooth29which couples within the continuous annular groove15of the locking seat14cof end12or13engaged by the respective annular element9bor9c; indeed, each tooth29has a circumferential axial profile which mimics that of the continuous annular groove15and radially overhangingly protrudes from the lateral surface25(FIG. 5), so as to engage groove15in a snapping manner when the annular element9b,cis pushed into the respective seat14b, while the lateral surface25couples fit to the annular surface portion16of such a seat.

In particular, the radial teeth24and29have the same circumferential extension as the corresponding elastically deformable wings23,28, so as to ensure a firm hold of the annular elements8b,cand8b,c, in the respective seats14b,cand within the continuous annular grooves15.

Thereby, the annular elements8b,cand9b,cmade of plastic material and defining the axial shoulders7of bearing1are firmly constrained to the rings2,3in axial direction, also by virtue of the different stiffness of sectors18and19, but are not constrained in an angularly integral manner in the respective seats14b,cexcept due to the friction between each annular element8b,cor9b,cand the respective seat14b,c.

In the example shown, the first sectors18of each first8b,cand second9b,cannular element made of synthetic plastic material are provided, on a frontal face30thereof facing rollers4, with respective pockets31filled, in use, with a lubricating fluid, e.g. oil or grease. Pockets31are preferably obtained at the sectors18to prevent the elasticity of wings23,28from being disturbed and to not weaken the sectors19excessively. In all cases, pockets31may be obtained in any angular position on the faces30of the annular elements8and9.

In the example shown, the pockets consist of radially through, radial cuttings31, obtained on the faces30so as to interrupt both the respective radially outer20and inner32lateral surfaces of the annular element8b,cmade of synthetic plastic material and both the respective radially outer33and inner25lateral surfaces of the annular element9b,cmade of synthetic plastic material.

With reference now toFIG. 2, in which details either similar or equal to those described above are indicated by the same numerals for simplicity, reference numeral1bindicates a rolling bearing with cylindrical rollers4comprising an outer ring2and an inner ring3and annular elements8b,cand9cwhich are identical to those already described.

The only differences with bearing1consist in that an annular element9cis missing, so that the seat14cof end12is left empty, three shoulders7being sufficient to axially block the rollers4, and in that bearing1bhas a small number of rollers4(while bearing1is of the full-complement roller type) which are held by a cage34, which is missing in bearing1.

It is apparent that only two shoulders7could be sufficient to ensure the axial blocking of rollers4, provided that they are mounted on opposite sides, whereby the annular element8cfitted in the seat14bof end11could also be missing.

Various bearing configurations can be obtained, simply and rapidly, using the same rings2,3by virtue of the construction of shoulders7by means of independent annular elements made of synthetic plastic material. Furthermore, the rollers4axially touch the faces30made of synthetic plastic material, which may be selected so as to have low friction, e.g. containing polytetrafluoroethylene or other material having similar creep properties, which are however lubricated with the lubricating fluid which is collected in pockets31.

The shape of the annular elements8,9and of seats14b,cthen allows to ensure an optimal axial blocking and simultaneously an easy snap-insertion of the elements8,9in seats14b c.

All the objects of the invention are thus achieved.