GB2054767A

GB2054767A - A radial-axial rolling bearing assembly

Info

Publication number: GB2054767A
Application number: GB8013953A
Authority: GB
Original assignee: Industriewerk Schaeffler OHG
Current assignee: IHO Holding GmbH and Co KG
Priority date: 1979-04-28
Filing date: 1980-04-28
Publication date: 1981-02-18
Also published as: IT8020522A0; DE2917425A1; GB2054767B; FR2455208A1; FR2455208B1; IT1129625B

Abstract

A radial-axial roller bearing assembly suitable especially for mounting a machine tool spindle 5, 6 formed with a helical ball track is of the kind having a set of radial load- supporting rollers 3 between radially outer and inner races 2 and 4 and two sets of axial load-supporting rollers 7 between race rings 8, 9 and corresponding ends of the outer race 2. In order to seal such a bearing assembly against leakage of lubricant therefrom, there is secured to one end of the outer race 2, in axial alignment with the latter, a carrier ring 13 which extends axially over the race ring 9 and carries a sealing ring 17 slidably engaging the outer circumference of the said race ring 9. <IMAGE>

Description

SPECIFICATION A radial-axial rolling bearing assembly This invention relates to a radial-axial rolling bearing assembly, particularly, but not exclusively, for mounting a ball screw in a machine tool, the said rolling bearing assembly being of the kind comprising an annular arrangement of radial loadsupporting cylindrical rollers; two annular arrangements of axial load-supporting cylindrical rollers; a radially outer race having, on its radially inner circumference, a radially outer race track for the radial load-supporting rollers and, on its two axially outer ends, axially inner race tracks for the axial load-supporting rollers of the two annular arrangements respectively of such rollers; a radially inner race having, on its radially outer circumference, a radially inner race tracks for the radial load-supporting rollers; and two race rings lying against the two axially outer ends respectively of the radially inner race and having, on their mutually confronting sides, axially outer race tracks for the axial load-supporting rollers of the two annular arrangements respectively of such rollers.

Sealing such bearing assemblies frequently represents a special problem when installing radial-axial rolling bearing assemblies of this kind.

Often, such bearings are provided with recirculating oil lubrication, in which case particular sealing problems occur because of the relatively large amounts of oil involved. Hitherto, the user of bearing assemblies of this kind was obliged to take special steps to provide a satisfactory sealing means. For this purpose, he generally had to provide suitable seating surfaces for a seal on the housing which carried the bearing assembly and in addition had to mount on the shaft separate members with which the sealing means could co-operate. The manufacturing cost of, and not least the amount of space required by, such sealing means was considerabie and was unacceptable in many cases.

It is accordingly an object of the present invention to provide a bearing assembly of the kind jnitially referred to, using very simple structural means, with a seal which is connected to the bearing assembly to form a structural unit therewith and which therefore will, in practice, be supplied together with the bearing.

With this object in view, the present invention provides a bearing assembly of the kind referred to in which a carrier ring is secured to one of the axially outer end faces of the outer race so that it is axially aligned with the latter, the said carrier ring extending axially over the race ring which is located at the corresponding end of the bearing assembly and carrying a sealing ring which is in sliding engagement with the outer circumference of the iast-mentioned race ring.

With such an arrangement it is only necessary to provide, apart from the sealing ring itself, a single additional component, namely the carrier ring which carries the sealing ring. The carrier ring can be a simple component symmetrical about its axis of rotation, and, in order to provide for centering thereof on the outer race, it is only necessary to provide coaxial cylindrical interengaging surfaces on the carrier ring and on the outer race. In relation to the extremely accurate machining of the outer race of the bearing assembly, which is required in any case, the provision of a precise centering surface of this kind represents only a slight increase in cost.

Because the sealing ring slidably engages against the outer circumference of one of the race rings, it is not necessary to provide a separate component therefor. The race ring at the corresponding end of the assembly which is required in any case is used, on the contrary, to perform the second function of co-operating with the seal. A bearing assembly embodying the invention is shown in longitudinal section in the accompanying drawing.

Disposed in a bore in a housing 1 is the outer race 2 of a radial-axial rolling bearing assembly.

Cylindrical rollers 3 are arranged to roll in the bore of the outer race 2, the inner track for the rollers 3 being formed by an inner race 4 which is carried on a cylindrical journal portion 5 of a ball screw 6.

Two rings 7 of rollers are arranged to roll against the two end faces respectively of the outer race 2, the second tracks for these rings 7 of rollers being formed on race rings 8 and 9. The race ring 8 which is shown on the right in the drawing bears by way of a spacer ring 10 against a shoulder of the spindle 6. A clamping nut 11 which co-operates with a screw-threaded portion 12 of the spindle bears against the race ring 9 which is shown on the left in the drawing. By rotating the nut 1 , the assembly of components comprising the spacer ring 10, the two race rings 8 and 9 and the inner race 4 can be firmly clamped between the nut 11 and the shoulder on the spindle 6.

A carrier ring 1 3 is fitted against the left-hand end face of the outer race 2 and is secured in position by screws 14. A sealing ring 1 5 is provided between the outer race 2 and the carrier ring 13. In order to ensure that the carrier ring 1 3 will occupy a precisely concentric position with respect to the outer race 2, it is supported on a centering shoulder 1 6 on the outer race 2.

A seal 17, which is fitted into the carrier ring 13, slidably engages the outside surface of the race ring 9.

In the embodiment illustrated, the outer race 2, and thus the entire bearing unit, is fixedly connected to the housing 1 by a plurality of circumferentially distributed screws 18, only one of which is visible in the drawing.

In the embodiment illustrated, the bearing assembly is lubricated by circulating oil. For this purpose an oil feed bore 1 9 and an oil discharge bore 20 are provided in the housing 1. The bores 19 and 20 are connected to an oil circuit (not shown). The oil feed bore 1 9 opens into an axial bore 21 in the outer race 2, which is crossed by a radial bore 22. The two bores 21 and 22 are closed at their outer ends by inserted plugs 23.

The oil supplied to the bearing passes through the radial bore 22 to reach the cylindrical rollers 3 which carry the radial load, and from there is conveyed outwardly by centrifugal force to the annular arrangements 7 of rollers which carry the axial load. From there the oil is passed by way of an axial bore 24 in the outer race 2 to the oil discharge bore 20. For this purpose, the latter has a transverse bore 25 which opens into the region of the second ring 7 of rollers. The carrier ring 13 has a plurality of oil inlet and oil outlet openings 26 distributed circumferentially thereof.

Claims

1. A radial-axial bearing assembly of the kind comprising an annular arrangement of radial loadsupporting cyclindrical rollers; two annular arrangements of axial load-supporting cyclindrical rollers; a radially outer race having, on its radially inner circumference, a radially outer race track for the radial load-supporting rollers and, on its two axially outer ends, axially inner race tracks for the axial load-supporting rollers of the two rings respectively of such rollers; a radially inner race having, on its radially outer circumference, a radially inner race track for the radial loadsupporting rollers; and two race rings lying against the two axially outer ends respectively of the radially inner race and having, on their muturally confronting sides, axially outer race tracks for the axial load-supporting rollers of the two rings respectively of such rollers, characterised in that a carrier ring is secured to one of the axially outer end faces of the outer race so that it is axially aligned with the latter, the said carrier ring extending axially over the race ring which is located at the corresponding end of the bearing assembly and carrying a sealing ring which is in sliding engagement with the outer circumference of the last-mentioned race ring.

2. A radial-axial bearing assembly according to claim 1, characterised in that the outer race is formed with a plurality of circumferentially distributed axial bores for the admission and/or discharge of a lubricant for lubricating the rollers and the carrier ring is formed, in the region thereof adjacent said axial bores, with openings for the passage of the lubricant.

3. A radial-axial bearing assembly substantially as described with reference to and as shown in the accompanying drawing.