DE102007001919A1 - Rolling bearing device for spindles, in particular motor spindles - Google Patents

Abstract

Rolling bearing device for spindles, in particular motor spindles, comprising a tandem bearing with a, seen in Spindelachsrichtung, inner and outer bearings in the form of angular contact ball bearings, which are operated under radial bias, wherein at least the inner roller bearing has an outer ring, wherein both rolling bearings (3a, 3b ) in a common sleeve (7) o. The like. Incorporated and a means (15) for compensating thermally induced changes in the radial bias, comprising on the in an axial sliding fit in the sleeve (7) o. The like. 6a) of the inner roller bearing (3a) axially acting clamping element (10) is provided.

Description

Field of the invention

The The invention relates to a rolling bearing device for Spindles, in particular motor spindles, comprising a tandem bearing with a seen in Spindelachsrichtung inner and an outer Rolling bearings in the form of angular contact ball bearings under radial bias can be operated.

Background of the invention

at many spindles, especially in motor spindles, forms in the Operation, for example, by the heat input of the engine a temperature gradient in the axial direction of the shaft center to out of the shaft ends. After such spindles usually over a tandem bearing, so two axially behind each other connected bearings are mounted on a housing or other component, Consequently, the rolling bearings also experience the temperature gradient. where it adjusts there both axially and radially. The temperature gradient can sometimes be increased in the axial and radial directions be that the housing or the component to which the rolling bearings are arranged, is additionally cooled. therefore Consequently, there is a considerable axial temperature gradient a, wherein the inner, closer engine closer bearings warmer is as the outer, as well as a radial Temperature gradient sets in each roller bearing, wherein The inner bearing ring is warmer than the outer one. In the high precision angular contact ball bearings commonly used in motor spindles This ultimately leads to different changes of the axial supernatant within a tandem pair.

One Another effect is due to the different temperatures conditional different thermal elongation of Shaft and housing, whereby naturally the warmer wave stretches harder than the cooled one Casing. As a result, the inner rings of the tandem hair migrate farther apart than the housing side fixed outer rings.

At long last lead the different temperature gradients to different Loads on the individual rolling bearings of a tandem pair, where the inner, that is closer to the engine or more heated Warehouse is loaded more heavily, so therefore a bias there is significantly more increased than in the outer Bearing, where it may also lead to a bias loss can come with corresponding slippage damage.

Out DE 10 2004 048 720 A1 is a ball bearing, which is particularly suitable for supporting the main spindle of a machine tool, known in which to compensate for the temperature-induced radial stress increase, which leads to increasing friction between the bearing rings and the rolling elements, whereby too much frictional heat is generated, the permissible operating temperature of the bearing exceeds and optionally burns the lubricating film, the outer bearing ring is formed in the form of two separate bearing rings, both of which are accommodated in a sliding sleeve. The one bearing ring is rigidly received in the sliding sleeve, currency rend the other is arranged axially displaceable against the restoring force of a spring. The bearing is thus formed within this sliding sleeve both as the temperature-related difference in length of the main spindle relative to the fixed bearing seat compensating floating bearing and as the temperature-induced radial stresses between the inner bearing ring and the outer bearing rings compensating, self-biased three-point bearing. This embodiment is very complex, since it requires separate outer bearing rings, as ultimately results in a disassembly movement of these two bearing rings only a three-point support.

Summary of the invention

Of the The invention is thus based on the problem of a rolling bearing device specify that simply run and for tandem bearings suitable is.

to The solution to this problem is in a rolling bearing device of the type mentioned above provided according to the invention, that both bearings in a common sleeve or the like, and that means for Compensation of thermally induced changes in the radial preload comprising one in an axial sliding fit in the sleeve or the like supported outer ring of the inner rolling bearing axially acting clamping element is provided.

In the rolling bearing device according to the invention, a voltage compensation device is provided only on the inner rolling bearing, that is to say the thermally more heavily loaded roller bearing on which a stronger temperature gradient is to be expected. It has proved to be sufficient only to make the compensation there. According to the invention now has the higher-loaded inner bearing on the outer ring a sliding seat, so is received with its outer ring axially displaceable in the sleeve or the like holding element. In addition, it is clamped over an axially acting Spannele element. After it is angular contact ball bearings in both bearings, arises in the case of a given temperature gradient due to expansion on the outer bearing ring axially acting force vector, which moves the received in the sliding seat outer bearing ring in the event of temperature-induced expansion axially against the spring element. In this embodiment of the invention, therefore, only an outer bearing ring, which is directly axially biased, is provided, wherein the axial movement is made possible due to the use of an angular contact ball bearing.

The Rolling device according to the invention is thus very simple, special components such as special on each other tuned double bearing rings, etc. are not required, rather the voltage compensation takes place directly over the one-piece outer Bearing ring alone of the inner bearing, after a Increase in preload in the outer race and so that when exceeding the spring force of the outer ring is moved axially, resulting in a more uniform Stress on the entire tandem pair as a result of the bearing ring movement results.

The Clamping element itself is preferably a spring element, which serves as a plate spring, can be designed as a spiral spring or a leaf spring. Alternatively, the clamping element may also be a piezoelectric Actuator, so an electrically controlled clamping element, be conceivable are also hydraulically or pneumatically actuated actuators, wherein in these cases always a corresponding control line must be provided to the actuator. The use is also conceivable one of a shape memory alloy, then preferably also annular clamping element. As a shape memory alloy For example, a NiTi or CuZnAl alloy material may be used become. Such alloys are characterized by a shape transformation after reaching a certain transformation temperature, resulting from a structural change taking place at this temperature, out.

Of the Outer ring is suitably over a Secured against rotation, so he is not stuck with the Spindle connected inner ring rotates and makes it an unnecessary Friction load of the sliding seat comes.

at the rolling bearing device according to the invention It is imperative that the inner rolling bearing having an outer bearing ring. Also the outer one Rolling bearings can have such a separate outer Have bearing ring. It is also conceivable that the outer ring of the outer bearing of the sleeve or the like is formed directly, that is, that there is no separate bearing ring provided at all. This is easily possible, as a possible bias overshoot degraded according to the invention at the more heavily loaded inner roller bearing can be and therefore always a consistently good, slip-free Wälzkörperlauf at the sleeve side Career is given.

Brief description of the drawings

Further Advantages, features and details of the invention will become apparent below based on embodiments with reference to the Figures described. The figures are schematic representations and show:

1 a schematic representation, partially in section, of a rolling bearing device according to the invention of a first embodiment,

2 a schematic representation, partially in section, of a rolling bearing device according to the invention a second embodiment, and

3 a schematic representation, partially in section, of a rolling bearing device according to the invention a third embodiment.

Detailed description the drawings

1 shows a rolling bearing device according to the invention 1 comprising a tandem warehouse 2 consisting of two rolling bearings 3a . 3b , where the rolling bearing 3a the inner bearing and the rolling bearing 3b the outer rolling bearing, based on the arrangement of a spindle 4 For example, a motor spindle. The inner rolling bearing 3a becomes more thermally stressed during operation because it is closer to the engine than the outer bearing 3b ,

Every rolling bearing 3a . 3b includes an inner ring 5a . 5b , each on the spindle 4 is arranged, and in the example shown an outer ring 6a . 6b , The tandem camp 2 is inside a sleeve 7 arranged the two outer rings 6a . 6b overlaps. The two bearings are on the spindle side via a spacer ring 8th on which the two inner rings 5a . 5b abut, spaced from each other. In the area of the bearing outer rings is on the sleeve a radial web 9 provided, the two outer rings 6a . 6b spaced apart. Here is the outer ring 6b in the sleeve 7 Stable, while the outer ring 6a in a sliding seat on the sleeve 7 is arranged. This axially displaceable bearing ring 6a is also about a clamping element 10 , here a spring, axially biased, with the clamping element 10 on a stop flange 11 is counter-stored.

The two rolling bearings 3a . 3b are both designed as angular contact ball bearings, see the corresponding training of the running surfaces on the two bearing outer rings 6a . 6b , This angular contact ball bearing design now makes it possible to compensate for thermally induced changes in preload in the region of the more heavily loaded inner roller bearing and so overall for a more uniform bearing load of the entire tandem bearing 2 to sor gene.

The inner rolling bearing 3a is the more thermally loaded bearing during operation. It forms a radial temperature gradient after the spindle 4 warms up during operation, with it also the inner ring 5a , The outer ring 6a is colder, in contrast, especially when the sleeve 7 on a motor housing or the like which is actively cooled. So it turns out a considerable temperature gradient of the inner ring 5a to the outer ring 6a one. Due to the heating, the inner ring expands 5a something that raises something about the bullets 12a on the bearing ring 6a transmitted increase in the inherent bias results. The over the balls 12a however, due to the angular contact ball bearing design, an axial force vector transmitted due to the expansion force component has an axial force vector. This causes the outer bearing ring received in the sliding seat 6a against the clamping element 10 is moved, which in turn this is slightly compressed. Over this, the excessive bearing preload can be reduced and passed into the clamping element. It thus results on the inner roller bearing 3a no overload resulting from a corresponding preload loss on the outer roller bearing 3b would result. Rather, the preload can be kept largely constant at the inner bearing, so that also on the outer roller bearing 3a maintains a substantially constant bias voltage. Although a temperature gradient can also occur at this bearing, it is smaller than that at the inner rolling bearing since this rolling bearing is somewhat remote from the motor 3a occurring temperature gradient, so that there the voltage ratios do not change to such an extent as in the region of the inner bearing. Also, a bearing slip can be avoided.

The outer ring 6a is further about a rotation 17 secured so that it turns on a spindle 4 in which the two inner rings 5a . 5b and with them the rolling elements 12a . 12b be moved, not moving.

2 shows a further variant of a rolling bearing according to the invention. This also includes a tandem camp 2 with the inner bearing 3a and the outer rolling bearing 3b , The inner bearing rings 5a . 5b are in turn at the shaft 4 arranged, here are both rolling bearings 3a . 3b with their balls 12a . 12b designed as angular contact ball bearings. The inner rolling bearing 3a also here has an outer bearing ring 6a on top of a tensioning element 10 is biased and axially displaceable in the sleeve 7 is arranged. In this embodiment, the clamping element 10 against a disposed in the sleeve bearing ring 13 braced.

Unlike the design after 1 has the outer rolling bearing 3b no separate bearing ring. Rather, here is the sleeve 7 even with a tread 14 provided, the sleeve 7 So even forms the outer ring of the bearing 3b , The shape of the tread 14 corresponds to the required shape for the formation of an angular contact ball bearing.

Again, after the inventive balancing device 15 to compensate for the thermally induced change in the radial preload on the inner roller bearing 3a is provided, a corresponding Vorspannungsüberhöhung resulting from a thermally induced strain, be easily compensated and provided for a uniform bearing load.

A third embodiment of the invention is in 3 shown. The rolling bearing device 1 also has a tandem bearing comprising the two rolling bearings 3a and 3b on. The embodiment corresponds essentially to the embodiment according to FIG 1 However, there is no the two outer bearing rings 6a . 6b spaced annular collar on the sleeve 7 intended. Rather, the bearing ring 6b with a radially extending approach 16 provided, the side of the sleeve 7 embraces. He is also able to stand here while the bearing ring 6a is received in the sliding seat in the sleeve and also here via a balancing device 15 comprising the tensioning element 10 biased.

1

roller bearing device

2

tandem bearings

3a

roller bearing

3b

roller bearing

4

spindle

5a

inner ring

5b

inner ring

6a

outer ring

6b

outer ring

7

shell

8th

spacer

9

radial web

10

clamping element (Feather

11

clamping element (Stop flange)

12a

roll

12b

roll

13

Against bearing ring

14

tread

15

balancer

17

twist

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004048720 A1 [0005]

Claims (5)

Rolling bearing device for spindles, in particular motor spindles, comprising a tandem bearing with a seen in Spindelachsrichtung inner and outer bearings in the form of angular contact ball bearings, which are operated under radial bias, wherein at least the inner roller bearing has an outer ring, characterized in that both rolling bearings ( 3a . 3b ) in a common sleeve ( 7 ) or the like, and that a device ( 15 ) for compensating for thermally induced changes in the radial prestressing including in an axial sliding fit in the sleeve ( 7 ) o. The like salaried outer ring ( 6a ) of the inner bearing ( 3a ) axially acting clamping element ( 10 ) is provided. Rolling bearing device according to claim 1, characterized in that the clamping element ( 10 ) is a spring element. Rolling bearing device according to claim 1, characterized in that the clamping element ( 10 ) is a piezoelectric actuator or a shape memory alloy consisting of a clamping element or a hydraulic or pneumatic actuator. Rolling bearing device according to one of the preceding claims, characterized in that the outer ring ( 3a ) via an anti-twist device ( 17 ) is secured. Rolling bearing device according to one of the preceding claims, characterized in that the outer ring ( 6a ) of the outer rolling bearing ( 3b ) of the sleeve ( 7 ) o. The like. Is formed.