GB2315103A

GB2315103A - Linear bearing arrangement

Info

Publication number: GB2315103A
Application number: GB9713868A
Authority: GB
Inventors: Rainer Kleber
Original assignee: INA Waelzlager Schaeffler OHG
Current assignee: INA Waelzlager Schaeffler OHG
Priority date: 1996-07-10
Filing date: 1997-06-30
Publication date: 1998-01-21
Anticipated expiration: 2017-06-30
Also published as: IT1292478B1; DE19627765B4; FR2751038A1; DE19627765A1; GB2315103B; ITMI971591A0; ITMI971591A1; FR2751038B1; GB9713868D0

Abstract

A linear bearing arrangement comprises guide rail (1), a carrier body (6) and at least one pair of track rollers (5), each of which is configured as an outer bearing ring of a rolling bearing and supported on one side of the guide rail, the rolling elements (7) of the rolling bearing being disposed between the track rollers and inner bearing rings (8) fixed to the carrier body by screws (9) inserted into threaded bores (10). At least one of the rolling bearings comprises a clamping bush (12) with rubber-like elastic properties arranged in the bore of the inner bearing ring around the screw. The bush is pressed axially by the screw so as to urge the track roller towards the running rail. The bush may comprise a recess (13) on the side remote from the rail.

Description

1 1 1 2315103 LINEAR BEARING ARRANGEMENT The invention concerns a linear

bearing arrangement comprising a guide rail, a carrier body and at least one pair of track rollers each of which is configured as an outer bearing ring of a rolling bearing and supported on one side of the guide rail, the rolling elements of the roller bearing being disposed between the track rollers and inner bearing rings fixed to the carrier body by screws inserted through the inner bearing rings and screwed into threaded bores of the carrier body, at least one of the rolling bearings comprising a clamping bush with rubber-like elastic properties arranged in the bore of the inner bearing ring around the screw.

DE-OS 3829 276 illustrates a known linear bearing arrangement. To have the track rollers which are mounted on the carrier body press against the guide rail with a defined pre-tension, a radially elastic element such as a rubber O-ring is arranged between a screw and the inner bearing ring of the rolling bearing comprising the track roller. However, to be able to insert the elastic element into the gap formed between the inner bearing ring and the screw, it is necessary, in this case, to make a peripheral groove on the screw to serve as a retention means. Therefore, usual types of screws made in series are not suited for fixing such rolling bearings on the carrier body.

2 The same disadvantage is met in a linear bearing arrangement known from the document IDE-GM 89 05 064 because, in this case, excentric shank regions have to be provided on a part of the length of the screws.

In a linear arrangement known from the document IDE-GM 86 01 141, an adjustment of the roller on a guide rail is obtained in that the roller axle is displaced by a surrounding excentric bush. However, the production and the adjustment of such a bush are complicated and expensive. These prior art documents contain no information as to the manner of mounting the roller on the roller axle.

Embodiments of the invention provide a bearing arrangement in which the The object of the invention is to provide a bearing arrangement in which the track rollers can be fixed in a simple manner on the carrier body and be adjusted with a defined pre-tension on the guide rail using inexpensive components.

Embodiments of the invention achieve this object by the fact that the clamping bush is pressed together axially by the screw with which the rolling bearing is screwed on the carrier body, whereby the clamping bush urges the rolling bearing, and with it, the track roller, towards the running rail. In this way, a preadjusted track roller system with a minimum range or scatter of pre-tension values is created without the use of excentric screws. Such track roller systems with their standard dimension guide rails are readily exchangeable. In contrast, the tolerances required in the manufacture of the hitherto used combination of track roller guide carriages and guide rails were too large and resulted in a wide scatter of pre-tension values. improved functioning is obtained with the invention because, by reason of the deformation of the elastic clamping bush, the spacing of the track roller is optimally adjusted to the guide rail. This also eliminates the influence of 3 manufacturing tolerances of the guide carriage. Mounting is considerably facilitated because the track rollers get adjusted in an optimally reproducible manner relative to the rail due to the deformation of the clamping bush during the screwing-in of the fixing screws. The customer thus saves mounting time, and the possibility of using standard cheese head screws results in great cost savings.

The axis of the threaded bore of the carrier body for receiving the screw of the rolling bearing can be offset from the axis of the track roller, which is in contact with the running rail, towards the centre of the linear bearing. In this way, the gap dimension of the gap formed between the screw and the inner bearing ring of the rolling bearing for receiving the clamping bush is larger, as seen in a sectional view, on the side remote from the guide rail than on the side nearer the guide rail. When the elastic clamping bush is pressed completely into the gap by the screw, the radial displacement of the material of the clamping bush in the gap urges the inner bearing ring against the running rail.

In the non-installd state of the screw of the rolling bearing to be fixed on the carrier body, the axial length of the clamping bush is larger than the axial length of the inner bearing ring by a defined measure. This measure depends on the material.

On the outer side of its periphery further away from the running rail, the clamping bush can comprise. a recess. When the fixing screw is screwed in, the corresponding region of the clamping bush nearer the running rail thickens and presses the track roller, through the rolling bearing, against the running rail such that the track roller is then adjusted in place without play.

At least one additional annular metal bush can be arranged axially behind the clamping bush in the gap formed between the screw and the inner bearing ring for receiving the clamping bush. This results in the elastic clamping bush being 4 pressed together when the fixing screw is tightened because the axial force is transmitted through one or two undeformable annular bushes. Due to the resulting deformation of the elastic clamping bush, the track roller is adjusted against the rolling rail. It is also possible to expand the clamping bush from the inside by providing end bevels on the annular bush as is the case with annular spring elements.

Examples of embodiment of the invention are illustrated in the drawings and will be described more closely below. The drawings show:

Fig. 1 a cross-section through a linear bearing arrangement with one pair of track rollers mounted on rolling elements, and clamping bushes, each of which comprises a recess on the outer side of its periphery remote from the running rails. The clamping bush is shown in the left and the right half of the figure in its respective positions before and after the bearing screw has been screwed in completely; Fig. 2 a cross-section through a linear bearing arrangement with one pair of track rollers mounted on rolling elements, wherein at least one additional annular bush is arranged axially behind the clamping bush in the gap formed between the screw and the inner bearing ring of the rolling bearing for receiving the clamping bush. The clamping bush is shown in the left and the right half of the figure in its respective positions before and after the bearing screw has been screwed in completely.

A linear bearing arrangement in accordance to the invention comprises a guide rail 1 which is fixed by screws 2 to a machine stand 3. The guide rail 1 preferably comprises a metal support made, for example, of an aluminium alloy with steel running rails 4 disposed in grooves on the two long ends of the support.

A track roller 5 configured as an outer bearing ring of a rolling bearing is supported on each running rail 4. The rolling bearings are arranged preferably pairwise on the two sides of the guide rail 1 and serve to retain a carrier body 6 which is displaceable on the guide rail 1 in the longitudinal direction thereof. It is also possible, however, to provide two track rollers 5 on one side of the guide rail 1 and only one track roller 5 on the other side. Rolling elements 7 are arranged in each rolling bearing between the track roller 5 and an inner bearing j ring 8. The rolling.elements 7 in the present examples of embodiment are balls but it is also possible to use rolling elements such as rollers or needles.

Each of the inner bearing rings 8 is fixed on the carrier body 6 by means of a screw 9 inserted through the inner bearing ring 8 and screwed into a threaded bore 10 of the carrier body 6. Spacer rings 11 having an inner diameter corresponding to the diameter of the screws 9 are arranged, on the one hand, between the screw head and the inner bearing ring 8, and on the other hand, between the inner bearing ring 8 and the carrier body 6. In the present examples of embodiment, the carrier body 6 is mounted on the guide rail 1 on two pairs of rolling bearings with track rollers 5.

In Fig. 1, a clamping bush 12 with rubber-like elastic properties is arranged in each rolling bearing in the gap formed between the screw 9 and the inner bearing ring 8, the axial length of the clamping bush 12 being larger than that 6 of the inner bearing ring 8 by a difference dimension A h. When the screw 9 is screwed in to fix the inner bearing ring 8 on the carrier body 6, it exerts an axial force on the clamping bush 12 through the spacer rings 11. This causes the clamping bush 12 to be pressed entirely into the bore of the inner bearing ring 8 whereby the material of the clamping bush 12 is displaced not only axially but also radially, which means that the clamping bush 12 becomes shorter and thicker. In the gap between the inner bearing ring 8 and the screw 9, the clamping bush 12 presses radially against the inner bearing ring 8 and through this and the rolling elements 7, against the track roller 5.

When the screw 9 is screwed in completely, a recess 13 provided in a region of the periphery of the clamping bush 12 remote from the running rail 4 effects a thickening of the clamping bush 12 only on its side nearer the running rail 4. As a result of this, the rolling bearing including the track roller 5 is pressed towards the running rail 4 so that the track roller 5 is adjusted in place.

In case a clamping bush without a recess 13 is to be used, the pressing force of the press-fitted clpmping bush in the direction of the running rail 4 can be obtained by arranging the axis of the threaded bore 10 of the carrier body 6, and thus the screw axis, offset towards the centre of the linear bearing with respect to the axis of the track roller 5 and the rolling bearing. The screw 9 and the inner bearing ring 8 which form the receiving gap for the elastic clamping bush are then excentric to each other. As shown in the sectional view in Fig. 1, the gap dimension S, on the outer side of the linear bearing is larger than the gap dimensionS2 situated near the running rail 4, and is large enough to enable a positioning of the track roller 5 on the running rail 4 by a radial displacement of the inner bearing ring 8.

In the embodiment of Fig. 2, a shorter clamping bush 14 with rubber-like elastic properties is arranged between two additional annular bushes 15 which surround the screw 9. The annular bushes 15 are not deformable and can be 7 made, for example, of a metallic material. Before the screw 9 is screwed in, only the lower undeformable annular bush 15 projects out of the inner bearing ring 8. When the screw 9 is tightened, the annular bush 15 is pressed entirely into the rolling bearing and transmits the pressure force through its end to the clamping bush 14 to be deformed which is situated in the inner bearing ring 8.

1.

8 C L A 1 M S:

1. A linear bearing comprising a guide rail, a carrier body and at least one pair of track rollers each of which is configured as an outer bearing ring of a rolling bearing and supported on one side of the guide rail, the rolling elements of the roller bearing being disposed between the track rollers and inner bearing rings fixed to the carrier body by screws inserted through the inner bearing rings and screwed into threaded bores of the carrier body, at least one of the rolling bearings comprising a clamping bus with rubber-like elastic properties arranged in the bore of the inner bearing ring around the screw, wherein the clamping bush is pressed together axially by the screw of the rolling bearing fixed an the carrier body, whereby the clamping bush urges the rolling bearing, and with it, the track roller, towards the running rail.

Claims

2. The linear bearing of Claim 1, wherein the axis of the threaded bore of

the carrier body for receiving the screw of the rolling bearing is offset from the axis of the track roller, which is in contact with the running rail, towards the centre of the linear bearing.

3. The linear bearing of Claim 2, wherein the gap dimensions S, of the gap formed between the screw and the inner bearing ring of the rolling bearing for receiving the clamping bus is larger, as seen in a sectional view, on the side remote from the running rail than the gap dimension S, of said gap on the side nearer the running rail.

9 4. The linear bearing of any preceding Claim, wherein in the noninstalled state of the screw of the rolling bearing to be f ixed on the carrier body, the axial length of the clamping bus is larger than the axial length of the inner bearing ring by a difference dimension (A h).

5. The linear bearing of any preceding Claim, wherein the clamping bush comprises a recess on the outer side of its periphery remote from the running rail.

6. The linear bearing of any preceding Claim, wherein at least one additional annular bush is arranged axially behind the clamping bush in the gap formed between the screw and the inner bearing ring for receiving the clamping bush.

7. A linear bearing substantially as hereinbefore described with reference to Figure 1 or Figure 2.

1.