DE9005398U1 - Machine tool spindle bearing - Google Patents

Description

I)IPL-INQ. DIETER JANDER DR-INQ. MANFRED BÖNINQ

PATENT ATTORNEYS

European Patent Attorneys

KU(IH)RSt ENDAMM 66 1000 EiERLIN 15 Telephone 030/883 5071/72 Fax 030/8 83 86 25 Telegrams Consideration Berlin

PATMARK·

1170/21 306 EN 10 May 1990

Registration

the company

Universal Ball Bearing Factory GmbH

Kienhorststrasse 53

1000 Berlin 51

Machine tool spindle bearing

The invention relates to a bearing for the spindle of a machine tool with a grease-lubricated rolling bearing arranged in a housing on the spindle head side, which is protected against the ingress of coolant and/or dirt particles by an annular air outlet gap for a sealing air flow.

Bearings of the aforementioned type with grease-lubricated rolling bearings must be designed in such a way that they can be used over a wide speed range, i.e. a speed range

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Postgiroamt Berlin, Account 1743 84-100, Bank Code 10010010 Berliner Bank AG. Account 0110921900, Bank Code 100 20000

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from 1 to 10,000 revolutions per minute and more, ensure a high degree of machining accuracy. The fulfillment of this requirement causes problems, especially at high cutting speeds and cutting forces, since in these cases undesirable changes to the rolling bearings and their surroundings cannot be ruled out due to thermal influences. In order to keep such changes within limits, good heat dissipation from the bearing area must be ensured. In keeping with this objective, the invention is based on the task of showing a simple way of air cooling the rolling bearing in a generic bearing. This object is achieved according to the invention in that at least one further annular gap is provided between the air outlet gap and the rolling bearing, that cooling air originating from the sealing air source can be guided through the rolling bearing to a cooling air outlet from the side of the rolling bearing facing away from the further annular gap, and that the further annular gap forms a barrier that counteracts a mixing of the sealing air and cooling air flow.

Since the sealing air source is also used as a cooling air source in the bearing according to the invention, the effort required for air cooling of the rolling bearing remains within reasonable limits. In practice, only a few additional air ducts and a barrier, preferably designed as a labyrinth seal, are required to prevent the cooling air flow from being impaired by the sealing air flow. By choosing a suitable pressure for the compressed air and designing the line systems for the sealing air and the cooling air

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This ensures that, on the one hand, coolant and dirt particles do not penetrate into the rolling bearing and, on the other hand, that lubricating grease is not carried away from the rolling bearing.

Further details and features of the invention emerge from the subclaims and the following description of the particularly advantageously designed bearing shown in the attached drawing.

In the drawing, 1 is the spindle of a machine tool, which is mounted in a housing 2 by means of two roller bearings 3 and 4. The bearing 3 facing the spindle head 5 is held by a bearing cover 6, which protrudes with a web 7 into a groove 8 of a splash ring 9. The inner surface of a recess 10 of the bearing cover 6 and the outer surface of the splash ring 9 delimit an annular air outlet gap 11, from which sealing air can flow, which prevents the penetration of coolant and/or dirt particles into the roller bearing 3. The sealing air is supplied to the recess 10 via a sealing air channel 12, which, together with a cooling air channel 13, merges into a compressed air inlet channel 14, which is connected to a compressed air source (not shown) via the interposition of a throttle valve 15. The throttle valve is designed in such a way that it limits the overpressure of the air in the compressed air inlet channel 14 to a value of the order of 0.5 bar. The cooling air channel 13 is connected to the side of the rolling bearing 3 facing away from the spindle head 5 via an annular space 16 between a spacer sleeve 17 for the rolling bearings 3 and 4 and the housing 2. The pressure generated by the rolling bearing 3

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-Cooling air to be flowed can flow out via a cooling air outlet 18, which is formed by at least one downwardly open bore in the bearing cover 6.

The side walls of the web 7 of the bearing cover 6, together with the side walls of the groove 8 of the splash ring 9, delimit two annular gaps 19 and 20, which form parts of a labyrinth seal, which practically exclude any influence on the cooling air flow by the sealing air flow and vice versa. For this purpose, the annular gaps 19 and 20 are dimensioned such that their cross-section is smaller than half the cross-section of the air outlet gap 11, the cross-section of which in turn is essentially equal to the cross-section of the cooling air outlet 18.

It can be seen from the drawing that not only the roller bearing 3 facing the spindle head 5, but also the roller bearing 4 located near the drive pulley 21 for the spindle 9 is cooled. Since the roller bearing 4 does not require protection against penetrating coolant and dirt particles, it does not need to be protected by a sealing air seal; the problem of separating sealing air from cooling air therefore does not arise here. Of course, the proportion of cooling air allocated to the roller bearing 4 must be taken into account when dimensioning the line system for the compressed air.

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Claims (1)

Expectations : 1. Bearing for the spindle of a machine tool with a grease-lubricated roller bearing arranged in a housing on the spindle head side, which is protected against the ingress of coolant and/or dirt particles by an annular air outlet gap for a sealing air flow, characterized in that at least one further annular gap (19, 20) is provided between the air outlet gap (11) and the roller bearing (3), that cooling air originating from the sealing air source can be guided through the roller bearing (3) to a cooling air outlet (18) from the side of the roller bearing (3) facing away from the further annular gap (19, 20), and that the further annular gap (19, 20) forms a barrier which counteracts a mixing of the sealing air and cooling air flows. 2. Bearing according to claim 1, characterized in that between the air outlet gap (11) and the rolling bearing (3) at least two annular gaps (19, 20) are arranged, which form parts of a labyrinth seal. 3. Bearing according to claim 1 or 2, characterized in that the cross section of the air outlet gap (11) for the sealing air is substantially equal to the cross section of the cooling air outlet (18). k. Bearing according to one of claims 1 to 3, characterized in that the cross section of the further annular gap or the further annular gaps (19, 20) is smaller than or equal to half the cross section of the air outlet gap (11). «f. DIPL.-INO. DItTtR IANDtR I)R.-INQ. MANtRtD BÖNINQ ['Al [ N I ANUAI I I 5. Bearing according to one of claims 1 to 4, characterized in that the housing (2) for the spindle (1) is provided with a compressed air inlet channel (14) from which a sealing air channel (12) and a cooling air channel (13) branch off. 6. Bearing according to one of claims 1 to 5, characterized in that a throttle valve (16) serving to keep the pressure prevailing in it constant is connected upstream of the compressed air inlet channel (14). 7. Bearing according to claim 5 or 6, characterized in that the excess pressure of the air in the pressure inlet channel (14) is approximately 0.4 to 0.6 bar. 8. Bearing according to one of claims 1 to 7, characterized in that the flow resistances of the channels (12, 13) for the sealing air flow and the cooling air flow are essentially the same. ⁰ ^ Quo .< O ₀