Axial-radial rolling bearing

Abstract

The invention relates to an axial-radial rolling bearing (1), comprising an outer ring (2) and an inner ring (4), which is rotatably mounted on the outer ring via a radial bearing (6) and a first axial bearing (7), and comprising a shaft disc (5), which is rigidly connected to the inner ring and is mounted on the outer ring via a second axial bearing (8), wherein the radial bearing has a cage (18) and rolling elements (19) guided therein, which are axially supported on the inner ring by means of the cage in the operating state of the axial-radial rolling bearing. The cage is intended to have, on each of its axial sides, a side band with a radially inwardly projecting projection (21), wherein the projections engage in circumferential grooves (17) of the inner ring and run against groove walls (22) of the circumferential grooves in the operating state of the axial-radial rolling bearing.

Description

[0001] Axial-radial rolling bearings

[0002] The invention relates to an axial-radial rolling bearing, comprising an outer ring and an inner ring rotatably mounted on the outer ring via a radial bearing and a first axial bearing, and a shaft disk that is fixedly connected to the inner ring and mounted on the outer ring via a second axial bearing, wherein the radial bearing has a cage and rolling elements guided therein, which are axially supported on the inner ring by means of the cage in the operating state of the axial-radial rolling bearing.

[0003] Axial-radial rolling bearings of this type for machine tools are already known in the art, such as the rotary table bearings designated by the abbreviations RTC and YRT. Rotary table bearings are ready-to-install precision bearings for high-precision applications with combined loads. They accommodate radial and bilateral axial loads as well as tilting moments without backlash and are suitable for bearing arrangements with high requirements for running accuracy.

[0004] However, the current state of the art has the disadvantage that manufacturing axial-radial rolling bearings is cost-intensive, particularly because the production of the inner ring contour is complex in conventional axial-radial rolling bearings. The inner ring contour typically has an internal recess with a radial raceway and a side flange arranged axially on both sides of the radial raceway to hold the rolling elements in their axial position. This necessitates the manufacturing steps of soft turning, plunge grinding (oscillating in a separate operation), and flange grinding. Furthermore, hard turning requires a tool change, leading to a reduction in quality and increased costs.

[0005] An axial-radial rolling bearing of the type mentioned above is known from DE 10 2020 211 040 A1. In the operating condition of the axial-radial rolling bearing, the rolling elements of the radial bearing are axially supported on the inner ring by means of the cage. "Operating condition" refers to the condition in which the fully assembled bearing is installed in its intended environment and is loaded and moved according to its functional purpose.

[0006] The invention is based on the objective of avoiding or at least mitigating the disadvantages of the prior art. In particular, the geometry of the axial-radial rolling bearing is to be modified so that the manufacturing, especially of the inner ring, can be carried out precisely and cost-effectively. This objective is achieved by an axial-radial rolling bearing with the features of claim 1. Accordingly, the cage is to have a side band on each of its axial sides with a radially inwardly projecting projection, wherein the projections engage in circumferential grooves of the inner ring and, in the operating state of the axial-radial rolling bearing, abut the groove walls of the circumferential grooves. In this way, an axially fixed and rotatable connection between the cage of the radial bearing and the inner ring can be easily established.

[0007] In operating conditions, the rolling elements of the radial bearing are not guided and positioned axially directly by ground side flanges of the inner ring, but indirectly by the projections of the cage. This has the advantage that the contour of the inner ring can be simplified, particularly by omitting the side flanges, and the number of required manufacturing steps can be reduced without compromising functionality.

[0008] According to an alternative embodiment, the side bands can each have a radially outwardly projecting projection that engages radially in circumferential grooves of the outer ring. This allows for a simple axially fixed and rotatable connection between the cage of the radial bearing and the outer ring.

[0009] Advantageous further training is the subject of the sub-claims.

[0010] The inner ring can have an L-shaped cross-section, comprising a cylindrical section on whose outer surface a radial raceway of the radial bearing runs, and an annular section on whose end face an axial raceway of the first axial bearing runs.

[0011] The L-shaped inner ring has a particularly favorable geometry from a manufacturing perspective, with regard to machining and tool change effort, because the radial raceway forms the largest diameter of the outer surface and is therefore radially raised on both sides of the circumferential grooves compared to the remaining outer surface, which does not necessarily need to be machined.

[0012] The radial bearing and the axial bearings are typically roller bearings, with the roller diameter of the radial bearing being smaller than that of the axial bearings to minimize radial space requirements. In this respect, the diameter ratio dR / dA can be defined as: dR / dA < 0.5, where dR is the roller diameter of the radial bearing and dA is the roller diameter of the axial bearings.

[0013] The axial bearings can each have a cage with an axially inwardly projecting projection that axially overlaps an inner surface of the outer ring in order to contact the inner surface for radial positioning in the operating state of the axial-radial rolling bearing.

[0014] The cage of the radial bearing is designed to be in permanent sliding contact with an inner surface of the outer ring for the purpose of its radial positioning.

[0015] The present invention relates to a radial cage segment for rotary table bearings for the axial positioning of the rolling elements. In known rotary table bearings, the rollers in the radial row are guided axially by a flange, which prevents operational displacement and reduces jamming. Manufacturing the radial raceway in known rotary table bearings is complex, as the production of the flange, in particular, must be carried out in several work steps and is therefore time-consuming and expensive. In the bearing according to the invention, the rollers of the radial rows are guided axially by means of the cage, so that the flange for guidance can be dispensed with. The radial cage is designed with a side band that enables the axial fixation and operational support of the rolling elements on the axial contact surfaces of the inner ring. Furthermore, the cage can be installed in bearings with different pitch circles in the radial raceway.This is made possible in particular by the cage geometry being realized through a combination of a narrow overall height, segment opening angle, and partial recesses that increase flexibility. The present invention also relates to an axial-radial rolling bearing with an increased radial raceway. Thus, in contrast to the prior art, the radial raceway is not extended inwards, and the axial guidance of the rolling elements is not achieved via ground flanges on the inner ring, but rather via a segmented cage, which is held in the axial position by means of circumferential grooves in the inner or outer ring. The circumferential grooves can be produced in the soft or hardened state of the respective ring. The use of segmented cages also simplifies the assembly of the bearings.

[0016] The invention is explained below with the aid of the drawing. Figure 1 shows a longitudinal section of an axial-radial rolling bearing according to the invention;

[0017] Figure 2 shows an enlarged section of Fig. 1.

[0018] The depicted axial-radial rolling bearing 1 is used particularly in machine tools and is, in this case, a rotary table bearing. The axial-radial rolling bearing 1 has an outer ring 2, which is designed as an annular disk with (continuous) threaded holes 3 for screw fastening. The axial-radial rolling bearing 1 has an inner ring 4 and a shaft disk 5 rigidly connected to it by means of a screw connection. These are arranged coaxially with the outer ring 2 and are rotatably mounted relative to the outer ring 2 about the axis R. The rotational support is provided by a radial bearing 6 arranged radially between the inner ring 4 and the outer ring 2 and by two axial bearings 7 and 8 arranged axially on either side of the outer ring 2. The first axial bearing 7 is arranged axially between the inner ring 4 and the outer ring 2, and the second axial bearing 8 is arranged axially between the shaft disk 5 and the outer ring 2. The axial bearings 7, 8 are identical parts.

[0019] The wave disk 5 is annular. The inner ring 4 has an L-shaped cross-section, comprising a cylindrical section 9 on whose outer surface 10 an inner radial raceway 11 of the radial bearing 6 runs, and an annular section 12 that projects radially beyond the outer surface 10 and on whose inner end face 13 an outer axial raceway 14 of the first axial bearing 7 runs. An end face 15 of the wave disk 5 facing the end face 13 forms the outer axial raceway 16 of the second axial bearing 8. The ground radial raceway 11 forms the largest diameter of the outer surface 10 and is therefore radially raised compared to the remaining outer surface 10, which is unmachined on both sides of the circumferential grooves 17 running therein. Alternatively, the outer surface 10 can have a uniform diameter, apart from the circumferential grooves 17.

[0020] The radial bearing 6 has a cage 18 and rolling elements 19 in the form of needle rollers guided therein. The cage 18, which is preferably a (comprehensively multi-part) segmented cage, is in permanent sliding contact with an inner surface 20 of the outer ring 2. In the operating state of the axial-radial rolling bearing 1, the cage 18 guides and positions the rolling elements 19 relative to the inner ring 4 in the axial direction. For this purpose, the cage 18 has a side band on each of its axial sides with a radially inwardly projecting projection 21, wherein the projections 21 engage in the circumferential grooves 17 (radially) and abut the groove walls of the circumferential grooves 17 (axially). In the present embodiment, the projections 21 abut the (relatively closely spaced) inner groove walls 22. The axial bearings 7, 8 are – like the radial bearing 6 – each roller bearings and are identical components in this case.The roller diameter dR of the radial bearing 6 is smaller than the roller diameter dA of the axial bearings 7, 8, according to the operating load conditions at the axial-radial rolling bearing 1. In this case, their diameter ratio is: dR / dA < 0.5. The axial bearings 7, 8 each have a cage 23 with an axially inwardly projecting projection 24, which axially overlaps the inner surface 20 of the outer ring 2 in order to contact the inner surface 20 of the axial-radial rolling bearing 1 during operation and to guide the respective axial bearing 7, 8 radially.

Claims

Patent claims 1. An axial-radial rolling bearing (1) comprising an outer ring (2) and an inner ring (4) rotatably mounted on the outer ring (2) via a radial bearing (6) and a first axial bearing (7), and a shaft washer (5) fixedly connected to the inner ring (4) and mounted on the outer ring (2) via a second axial bearing (8), wherein the radial bearing (6) has a cage (18) and rolling elements (19) guided therein, which, in the operating state of the axial-radial rolling bearing (1), are axially supported on the inner ring (4) by means of the cage (18), characterized in that the cage (18) has on each of its axial sides a side band with a radially inwardly projecting projection (21), wherein the projections (21) engage in circumferential grooves (17) of the inner ring (4) and, in the operating state of the axial-radial rolling bearing (1), bear against groove walls (22) the circumferential grooves (17) begin.

2. Axial-radial rolling bearing (1) according to claim 1 , characterized in that the inner ring (4) has an L-shaped cross-section with a cylindrical section (9) on whose outer surface (10) a radial raceway (11) of the radial bearing (6) runs, and an annular section (12) on whose end face (13) an axial raceway (14) of the first axial bearing (7) runs.

3. Axial-radial rolling bearing (1) according to claim 2, characterized in that the radial raceway (11) forms the largest diameter of the outer shell surface (10).

4. Axial-radial rolling bearing (1) according to one of the preceding claims, characterized in that the radial bearing (6) and the axial bearings (7, 8) are designed as roller bearings, wherein the roller diameter dR of the radial bearing (6) is smaller than the roller diameter dA of the axial bearings (7, 8).

5. Axial-radial rolling bearing (1) according to claim 4, characterized by the diameter ratio dR / dA < 0.

5.

6. Axial-radial rolling bearing (1) according to one of the preceding claims, characterized in that the cage (18) of the radial bearing (6) is in permanent sliding contact with an inner surface (20) of the outer ring (2).

7. Axial-radial rolling bearing (1) according to one of the preceding claims, characterized in that the axial bearings (7, 8) each have a cage (23) with an axially oriented have an internally projecting projection (24) which axially overlaps an inner surface (20) of the outer ring (2) in order to run up against the inner surface (20) in the operating state of the axial-radial rolling bearing (1).

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