DIAGNOSTIC METHOD FOR A BALL BEARING, IN PARTICULAR FOR AN ANGULAR-CONTACT BALL BEARING, A CORRESPONDING DIAGNOSTIC SYSTEM, AND USE OF THE DIAGNOSTIC SYSTEM

• US 20090299663A1
• Filed: 06/01/2009
• Published: 12/03/2009
• Est. Priority Date: 06/02/2008
• Status: Active Grant

• Current Assignee: Weiss Spindeltechnologie GmbH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: BUTZ, FELIX, Gebert, Karl
• Granted Patent: US 8,315,826 B2
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

In a diagnostic method for at least one ball bearing, in particular for an angular-contact ball bearing for bearing a rapidly rotating spindle, mechanical vibration caused by the respective angular-contact ball bearing is acquired by at least one vibration sensor and outputted as a corresponding vibration signal. At least one bearing characteristic, fundamental kinematic frequency dependent on a current bearing rotational frequency is determined by computation. A corresponding bearing frequency in a measurement frequency spectrum of the respective vibration signal is determined by measurement. A first diagnostic message is output when at least one of the determined bearing frequencies deviates by a respective prescribed frequency deviation from the corresponding computational fundamental kinematic frequency.

Claims

1. A diagnostic method for a ball bearing, comprising the steps of:

measuring mechanical vibrations produced by the ball bearing with a vibration sensor and generating a corresponding vibration signal having a frequency spectrum;

computing at least one fundamental kinematic frequency, with the fundamental frequency depending on a current rotation frequency of the ball bearing;

determining from the measured frequency spectrum at least one bearing frequency; and

outputting a first diagnostic message when the at least one bearing frequency deviates from the at least one fundamental kinematic frequency by a predefined frequency deviation.

2. The diagnostic method of claim 1, wherein the at least one bearing frequency is determined as a frequency having a maximum amplitude at its respective frequency position in the measured frequency spectrum.

3. The diagnostic method of claim 1, further comprising the step of outputting a second diagnostic message when a maximum amplitude of the at least one bearing frequency exceeds of a predefined limit amplitude.

4. The diagnostic method of claim 1, wherein the at least one fundamental kinematic frequency is selected from the group consisting of a rollover frequency of a bearing outer race, a rollover frequency of a bearing inner race, a rotation frequency of a bearing cage, and a rollover frequency of a roll body region of the ball bearing.

5. The diagnostic method of claim 1, wherein the at least one fundamental kinematic frequency depends on a nominal pressure angle between a bearing inner race and a bearing outer race of the ball bearing.

6. The diagnostic method of claim 5, wherein the at least one bearing frequency is computationally mapped to a current operating pressure angle.

7. The diagnostic method of claim 6, further comprising the step of outputting a third diagnostic message when the current operating pressure angle deviates from the nominal pressure angle by a predefined maximum pressure angle deviation.

8. The diagnostic method of claim 1, wherein the ball bearing is an angular-contact ball bearing.

9. A diagnostic system for a ball bearing, comprising:

at least one vibration sensor for measuring a mechanical vibration produced by the ball bearing and for outputting a vibration signal representative of the mechanical vibration; and

a measurement evaluation unit operatively connected to the at least one vibration sensor, said measurement evaluation unit having

computation means for determining at least one fundamental kinematic frequency that is characteristic for the bearing and depends on a current rotation frequency of the bearing,

frequency measuring means for determining at least one bearing frequency from a measured frequency spectrum of the vibration signal, and

comparison means for outputting a first diagnostic message when at least one measured bearing frequency deviates from the at least one fundamental kinematic frequency by a predefined frequency deviation.

10. The diagnostic system of claim 9, wherein the ball bearing is an angular-contact ball bearing.

11. The diagnostic system of claim 9, wherein the frequency measuring means comprises an amplitude meter for measuring a maximum amplitude, with a frequency position of the maximum amplitude in the measured frequency spectrum determining the at least one bearing frequency.

12. The diagnostic system of claim 9, wherein the frequency measuring means comprises an amplitude meter for measuring a maximum amplitude of the at least one bearing frequency and means for outputting a second diagnostic message when the maximum amplitude exceeds a predefined limit amplitude.

13. The diagnostic system of claim 9, wherein the at least one fundamental kinematic frequency is a frequency selected from the group consisting of a rollover frequency of a bearing outer race, a rollover frequency of a bearing inner race, a rotational frequency of a bearing cage, and a rollover frequency of a rolling body region of the ball bearing.

14. The diagnostic system of claim 9, wherein the at least one fundamental kinematic frequency depends on a nominal pressure angle between a bearing inner race and a bearing outer race of the ball bearing.

15. The diagnostic system of claim 9, wherein the measurement evaluation unit comprises mapping means for mapping the at least one bearing frequency to an operating pressure angle based on a computational model.

16. The diagnostic system of claim 15, wherein the measurement evaluation unit comprises means for outputting a third diagnostic message when the operating pressure angle deviates from a nominal pressure angle by a predefined maximum pressure angle deviation.

17. The diagnostic system of claim 9, for use in the diagnosis of the ball bearing supporting a spindle of a spindle system.

18. The diagnostic system of claim 17, wherein spindle system is part of a machine tool.