Process and apparatus for determining damage to cyclically moving machine components

• US 6,526,829 B1
• Filed: 08/14/2000
• Issued: 03/04/2003
• Est. Priority Date: 08/16/1999
• Status: Expired due to Term

• Current Assignee: PRÜFTECHNIK Dieter Busch AG (Fortive Corp.)
• Original Assignee: PRÜFTECHNIK Dieter Busch AG (Fortive Corp.)
• Inventors: Franke, Dieter, Lysen, Heinrich
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/637,583
• Time in Patent Office: 932 Days
• Field of Search: 735/93, 736/59, 736/60
• US Class Current: 73/593
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01M 13/021 Gearings
• CPC Class Codes: G01M 13/028 Acoustic or vibration analysis
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

A process and apparatus for determining the damage on at least one cyclically moving machine component, whereby a signal caused by the motion of the component is picked up by a sensor. At least one portion of the signal with an adjustable period is separated, and the remaining or separated part of the signal is subjected to damage analysis. In addition, a process and apparatus for separating periodic signal portions from a signal is provided, whereby the signal is supplied as an input signal to a rotating ring storage which is formed by cyclically arranged storage elements which are supplied in succession with the input signal currently at the input of the ring storage. A rotation frequency is synchronized with the period duration of the desired signal portions, and the desired signal portions are obtained as the output signal of the ring storage.

Claims

1. A process for separating periodic time signal portions from a signal, said process comprising the steps of:

providing a rotating ring storage having a plurality of cyclically arranged storage elements being connected in succession to an input device, said ring storage having a controllable rotational frequency;

supplying an input signal to said ring storage;

obtaining at least one desired signal portion as an output signal from said at least one rotating ring storage

synchronizing a rotation frequency of said ring storage with a period duration of said desired signal portion.

2. The process as claimed in claim 1, wherein said plurality of storage elements acts as a lowpass filter for said input signal.

3. The process as claimed in claim 2, wherein a lowpass filtering action of the lowpass filter of said plurality of storage elements is digitally simulated.

4. The process as claimed in claim 3, wherein said ring storage is digital and said plurality of storage elements are cyclically-addressed accumulators.

5. The process as claimed in claim 4, wherein said plurality of storage elements are provided in a number which corresponds to a product of the rotational frequency and a sampling rate with which said input signal is digitized.

6. The process as claimed in claim 4, wherein an average value of said input signal occurring during an interval in which said plurality of storage elements is supplied with the input signal is accumulated for each plurality of storage elements during said interval.

7. The process as claimed in claim 1, wherein a frequency matching of said ring storage occurs by a period duration of a desired signal portion determined from said signal and said ring storage is rotated with said rotational frequency determined in this way.

8. The process as claimed in claim 7, wherein a period duration is determined by at least one of search tone analysis, Fourier transform and cepstrun analysis.

9. The process as claimed in claim 1, wherein the rotation of said ring storage is synchronized directly with said input signal.

10. The process as claimed in claim 9, wherein said synchronization occurs using a phase shifter.

11. The process as claimed in claim 10, wherein contents of said plurality of storage elements are multiplied by a derivative of said input signal with a resultant value being accumulated.

12. The process as claimed in claim 11, wherein said rotational frequency of said ring storage is changed according to said accumulated value.

13. The process as claimed in claim 10, wherein a shape of said input signal is processed for synchronization.

14. The process as claimed in claim 13, wherein said input signal is low-pass filtered for synchronization.

15. The process as claimed in claim 13, wherein for synchronization at least a portion of said input signal which does not have a period duration of said desired signal portions is removed from said input signal using a second rotating ring storage.

16. The process as claimed in claim 9, wherein said ring storage comprises at least three ring storages for receiving an input signal, said at least three ring storages rotating with a different period duration.

17. The process as claimed in claim 16, wherein an instantaneously largest output signal is determined during operation of one of said at least three ring storages.

18. The process as claimed in claim 17, wherein said instantaneously largest output signal is output as a valid output signal and said period duration of said at least three ring storages is changed depending upon which one of said at least three ring storages instantaneously has the largest output signal.

19. The process as claimed in claim 18, wherein the period duration of said at least three ring storages is changed in a same direction.

20. The process as claimed in claim 19, wherein said period duration is lengthened when one of said at least three ring storages with a period duration longer than an average period duration of said at least three ring storage has the instantaneously largest output signal.

21. The process as claimed in claim 19, wherein said period duration is shortened when one of said at least three ring storages with a period duration shorter than an average period duration of said at least three ring storages has the instantaneously largest output signal.

22. The process as claimed in claim 19, wherein said period duration is not changed when one of said at least three ring storages with a period duration equal to an average period duration has the instantaneously largest output signal.

23. The process as claimed in claim 1, wherein the contents of said plurality of storage elements are mapped into in a steady-state storage once said output signal exceeds a predetermined threshold value.

24. The process as claimed in claim 1, wherein a difference between said input signal and said output signal of said ring storage is formed to eliminate said desired signal portions from said output signal.

25. The process as claimed in claim 1, wherein said ring storage comprises a plurality of ring storages having different rotation frequencies for extracting signal portions with different period durations.

26. The process as claimed in claim 25, wherein said plurality of ring storages being interconnected such that an output signal from a respective one of plurality of ring storages is subtracted from an input signal from the remaining said plurality of ring storages.

27. The process as claimed in claim 1, wherein said ring storage comprises plurality of ring storages for acquiring an identical input signal and which rotate with different period durations.

28. The process as claimed in claim 27, wherein at least one of an output signal of each of said plurality of ring storages being output for at least one of evaluation and the output signal of one of said plurality of ring storages with the largest output signal being automatically selected for further evaluation.

29. A period form filter for separating periodic signal portions from a signal, said period form filter comprising:

a rotating ring storage having a plurality of cyclically arranged storage elements connected in succession to an input device which sends a signal of a rotation frequency of said rotating ring storage to said storage elements; and

a synchronization means for synchronizing said rotational frequency with a period duration of a desired signal portion.

30. The period form filter as claimed in claim 29, further comprising a plurality of output devices respectively connected in succession to said plurality of storage elements according to the rotation frequency.

31. A process for determining damage on at least one cyclically moving machine component comprising the steps of:

providing a sensor;

sensing a signal caused by a movement of said at least one cyclically moving machine component using said sensor;

separating from said signal at least one signal portion with an adjustable period; and

analyzing a remaining portion of said signal to determine if damage has occurred to said at least one cyclically moving machine component.

32. The process as claimed in claim 31, wherein said adjustable period is a period of revolution of a shaft for driving said at least one cyclically moving machine component.

33. The process as claimed in claim 31, wherein said at least one cyclically moving machine component rotates and said signal is a vibration signal.

34. The process as claimed in claim 31, wherein said analyzing step is performed in a time domain of said separated signal portion.

35. The process as claimed in claim 31, wherein said at least one cyclically moving machine component is at least one of an outer ring, a rolling element and an inner ring of a roller bearing, the signal is an amplitude modulated noise signal and the adjustable period is a modulation period of the noise signal.

36. The process as claimed in claim 31, wherein said at least one cyclically moving machine component is a roller bearing, and wherein at least one of an amplitude modulated noise signal portion of the outer ring rollover frequency and a period of cage revolution signal portion is separated from said signal in order to derive information regarding bearing play.

37. The process as claimed in claim 36, wherein a modulation depth is used to evaluate bearing play.

38. The process as claimed in claim 31, wherein said at least one cyclically moving machine component is at least one of an outer ring, a rolling element and an inner ring of a roller bearing.

39. The process as claimed in claim 38, wherein a plurality of period form filters are assigned to at least one of said outer ring, said inner ring and said rolling element, and wherein at least one ring storage is provided, each of which has a respective specific rotational frequency of completed storage access that corresponds to a respective rotational frequency of said outer ring, said inner ring and said rolling element.

40. The process as claimed in claim 39, wherein said at least one rotating ring storage has a plurality of cyclically arranged storage elements that are connected in succession to an input device.

41. The process as claimed in claim 40, wherein the rotation frequencies of said at least one ring storage corresponds to at least one of a rollover frequency of said outer ring, a rollover frequency of said inner ring and a rollover frequency of said rolling element.

42. The process as claimed in claim 41, wherein said plurality of period form filters sends an output signal which is subtracted from a preceding output signal and is supplied to a respective at least one first period form filter as an input signal.

43. The process as claimed in claim 39, wherein a respective one of said plurality of period form filters being connected to a shaft for driving said at least one cyclically moving machine component, said respective one of said plurality of period form filters producing an output signal which is subtracted from a preceding output signal and is supplied to those remaining said plurality of period form filters as an input signal.

44. The process as claimed in claim 43, wherein said input signal is conditioned before it is supplied to said remaining plurality of period form filters.

45. The process as claimed in claim 44, further comprising a bandpass filter for filtering said input signal, said bandpass filter being set such that the output signal of said plurality of period form filters is at a maximum level for said inner ring.

46. The process as claimed in claim 45, wherein from a dynamic model, a transfer function is determined between a deflection of said rolling element caused by damage and a corresponding sensor signal.

47. The process as claimed in claim 46, wherein said sensor signal is corrected by a bandpass filter with respect to said transfer function before said sensor signal is supplied to said plurality of first period form filters.

48. The process as claimed in claim 47, wherein a bandpass filter is connected to a respective one of said plurality of first period form filters for said outer ring and a respective one of said plurality of period form filters for said inner ring.

49. The process as claimed in claim 48, wherein said corresponding bandpass filter corrects at least one of a transfer function for a damage signal originating from contact between said outer ring and said rolling element and a transfer function for a damage signal originating from contact between said inner ring and said rolling element.

50. The process as claimed in claim 49, wherein two of said plurality of period form filters are associated with said rolling element.

51. The process as claimed in claim 50, wherein one of said two of said plurality of period form filters being connected to said bandpass filters, said one of said two of said plurality of period form filters having a different transfer function from the second of said plurality of period form filters.

52. The process as claimed in claim 51, wherein a time change of the contents of said at least one ring storage of said plurality of period form filters for said outer ring, said inner ring and said rolling element is analyzed in order to determine at least one of an unbalanced load and balanced load acting upon said roller bearing.

53. The process as claimed in claim 52, wherein a sum of the balanced load and the unbalance load is determined by forming a ratio between amplitudes of said signal portions which originate from said inner ring contact and said outer ring contact for said output signal of the period form filter for said rolling element.

54. The process as claimed in claim 53, wherein a contact angle of said roller bearing is determined from the rotation frequency of said plurality of period form filters for said outer ring, said inner ring and said rolling element.

55. The process as claimed in claim 39, wherein a quality of said period form filter for said rolling element is set such that it transiently oscillates within one roller bearing revolution.

56. The process as claimed in claim 55, wherein a time constant of said period form filter for said rolling element is chosen as a product of a roller bearing period and a load angle divided by 360°

.

57. The process as claimed in claim 56, wherein with each revolution of the roller bearing a map of the ring storage is produced when the output is maximum.

58. The process as claimed in claim 57, wherein the ring storage is reset after each revolution and from the comparison of different maps a phase shift between the different maps and thus the slip angle of said rolling element is determined.

59. The process as claimed in claim 58, wherein the phase shift is determined from a maximum of a ring storage correlation between the individual maps.

60. The process as claimed in claim 58, wherein individual maps are corrected with respect to their phase shift and then added to form the output of said at least one period form filters.

61. The process as claimed in claim 55, wherein a phase of rotation of the ring storage of a period form filter corresponding to said rolling element is controlled according to the determined slip angle of said rolling element in order to compensate for rolling element slip.

62. The process as claimed in claim 39, wherein the output signal of each said at least one period form filters is sorted by its amplitude.

63. The process as claimed in claim 62, wherein a damage length for said outer ring, said inner ring and said rolling elements is determined from the amplitude-sorted signal.

64. An apparatus for determining damage on at least one cyclically moving machine component, said apparatus comprising:

a sensor for sensing an input signal produced by a movement of said at least one cyclically moving machine component;

separating means for separating said input signal into at least one portion with an adjustable period from a remaining portion of said input signal; and

,

analyzing means for analyzing at least one of said at least one portion with an adjustable period and said remaining portion.

65. The apparatus as claimed in claim 64, wherein said at least one cyclically moving machine component is a plurality of rotating gear components, each of which rotate with a different rpm.

66. The apparatus as claimed in claim 65, wherein at least one period form filter is assigned to each of said plurality of rotating gear components, with a ring storage which rotates with a frequency of rotation of each of said plurality of rotating gear components.

67. The apparatus as claimed in claim 64, wherein said at least one cyclically moving machine component is a plurality of rotating rollers used for stamping a surface of a continuous product.

68. The apparatus as claimed in claim 67, wherein at least one period form filter is assigned to each of said plurality of rotating rollers such that a signal is obtained from a profile of said continuous product in a feed direction.

69. The apparatus as claimed in claim 68, wherein a feed rate of said continuous product is acquired and used to synchronize said at least one period form filter.

70. A process for separating signal portions with a certain period from a signal, the process comprising the steps of:

dividing the signal into sections with a certain duration which corresponds approximately to a desired period duration;

storing the signal sections;

determining at least one of a phase shift and a direction of the phase shift of the signal sections;

correcting the signal sections with respect to the phase shift;

adding the signal sections which are phase-corrected to obtain a sum of the signal sections with a period duration to be determined.

71. The process as claimed in claim 70, wherein the signal sections are adjacent portions of said signal.

72. The process as claimed in claim 70, wherein the phase shift between a first of said signal sections and a second of said signal sections is determined.

73. The process as claimed in claim 71, wherein the first of said signal sections and the second of said signal sections are added phase-corrected and the resulting summation signal is stored, this procedure being iteratively repeated for other signal sections provided that each respective summation signal assumes the role of the first signal section and a signal section currently processed at the time assumes the role of the second signal section.

74. The process as claimed in claim 70, wherein the phase shift is determined by determining a maximum correlation between two different signal sections.

75. The process as claimed in claim 74, wherein the correlation is a ring correlation.

76. The process as claimed in claim 75, wherein a weighting of a signal section during addition is proportionate to the maximum correlation determined at the time.

77. The process as claimed in claim 70, wherein the desired period duration is verified and the signal section durations are matched to changes of the desired period duration.

78. The process as claimed in claim 70, wherein the signal is supplied as an input signal to a rotating ring storage which is formed by a plurality of cyclically arranged storage elements which are supplied in succession with the input signal supplied to an input port of the ring storage and said input signal having a rotation period which corresponds to the signal section duration.

79. The process as claimed in claim 78, wherein after a certain number of revolutions of the ring storage, storage contents are read out and stored as a map and the ring storage is reset.

80. The process as claimed in claim 79, wherein each map is added phase-corrected.