GB1603190A - Apparatus for detecting faults or defects in moving machine parts - Google Patents

Apparatus for detecting faults or defects in moving machine parts Download PDF

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Publication number
GB1603190A
GB1603190A GB15968/78A GB1596878A GB1603190A GB 1603190 A GB1603190 A GB 1603190A GB 15968/78 A GB15968/78 A GB 15968/78A GB 1596878 A GB1596878 A GB 1596878A GB 1603190 A GB1603190 A GB 1603190A
Authority
GB
United Kingdom
Prior art keywords
frequency
signal
oscillator
pick
defects
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB15968/78A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SKF Industrial Trading and Development Co BV
Original Assignee
SKF Industrial Trading and Development Co BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SKF Industrial Trading and Development Co BV filed Critical SKF Industrial Trading and Development Co BV
Publication of GB1603190A publication Critical patent/GB1603190A/en
Expired legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01MTESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M13/00Testing of machine parts
    • G01M13/04Bearings
    • G01M13/045Acoustic or vibration analysis

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Description

(54) APPARATUS FOR DETECTING FAULTS OR DEFECTS IN MOVING MACHINE PARTS (71) We, SKF INDUSTRIAL TRADING AND DEVELOPMENT COMPANY B.V. a Company organised and existing under the laws of the Kingdom of the Netherlands, of Plattenburgerweg, P.O.
Box 50, Nieuwegein, the Netherlands, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention concerns apparatus for detecting faults or defects in moving machine parts.
The invention provides apparatus for detecting faults or defects in moving machine parts comprising a non-acoustic pick-up for converting mechanical vibrations of a selected part of the machine into an electrical signal at the frequency of vibration, an oscillator for generating a reference signal at a predetermined frequency, a mixing or multiplying device connected to the pick-up and oscillator for combining the said signals to produce signals at the sum and difference frequencies, a low-pass filter connected to the mixing or multiplying device and arranged to discriminate against the signal of the sum frequency and to pass the signal of the difference frequency, and an indicating instrument connected to the lowpass filter to respond to the signal of the difference frequency.
The frequency of the oscillator signal may be higher than the frequency of the pick-up signal.
The indicating instrument may include a peak detector responsive to the signal of the difference frequency.
The oscillator may be tunable to adjust the frequency of the reference signal.
An embodiment of apparatus according to the invention will now be described by way of example and with reference to the accompanying drawings which is a diagram of the embodiment.
A piezo electric pick-up 1 is used to convert the mechanical vibrations of the moving machine part being tested, for example a bearing, into an electrical signal at the frequency fl of the vibration. The signal is then amplified in a pre-amplifier 2 and is then fed to a mixing or multiplying device 3. Also connected to the device 3 is a tunable oscillator 4 which generates a reference signal at a predetermined frequency f2 somewhat higher than the frequency of the pick-up signal.The mixing or multiplying device 3 combines the said signals to produce signals with a difference frequency f2-f1 and with a sum frequency f1+f2. A low-pass filter 5 is connected to the device 3 and is arranged to discriminate against the signal with the sum frequency f1+f2 and to pass the signal with the difference frequency f2-f1 to a peak detector 6 to which the filter 5 is connected.
The output from the detector 6 is then fed to an indicating instrument 7 such as a simple dial from which the magnitude of the fault or defect can be subsequently interpreted or measured.
An advantage of apparatus according to the invention is that the difference frequency f2-f1 is a low frequency making only a small demand of the analysis apparatus comprising peak detector 6 and indicating instrument 7 when compared to the demand when operating in the high frequencies. A non-critical low-pass filter 5 is used to discriminate against the signal with the sum frequency and to pass the signal with the difference frequency from the mixing and multiplying device 3. The magnitude of the difference frequency is thus indicative of the magnitude of the fault in the moving machine part, such as a bearing, under investigation.
A further advantage is that the resonant frequency of the signal from the pick-up 1 is not critical, since the oscillator 4 can be tuned to any desired frequency.
Furthermore the apparatus is, because of its selective nature, insensitive to interference signals picked up by~the pick-up 1 or the pre-amplifier 2. Also the apparatus is quite reliable since a peak detector is employed.
WHAT WE CLAIM IS: 1. Apparatus for detecting faults or defects in moving machine parts comprising a non-acoustic pick-up for converting mechanical vibrations of a selected part of the machine into an electrical signal at the frequency of vibration, an oscillator for generating a reference signal at a predetermined frequency, a mixing or multiplying device connected to the pick-up and oscillator for combining the said signals to produce signals at the sum and difference frequencies, a low-pass filter connected to the mixing or multiplying device and arranged to discriminate against the signal of the sum frequency and to pass the signal of the difference frequency, and an indicating instrument connected to the lowpass filter to respond to the signal of the difference frequency.
2. Apparatus as claimed in claim 1 wherein the frequency of the oscillator signal is higher than the frequency of the pick-up signal.
3. Apparatus as claimed in claim 1 or 2 wherein the indicating instrument includes a peak detector responsive to the signal of the difference frequency.
4. Apparatus as claimed in any preceding claim wherein the oscillator is tunable to adjust the frequency of the reference signal.
5. Apparatus for detecting faults or defects in moving machine parts substantially as herein described with reference to and as shown in the accompanying drawing.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. selective nature, insensitive to interference signals picked up by~the pick-up 1 or the pre-amplifier 2. Also the apparatus is quite reliable since a peak detector is employed. WHAT WE CLAIM IS:
1. Apparatus for detecting faults or defects in moving machine parts comprising a non-acoustic pick-up for converting mechanical vibrations of a selected part of the machine into an electrical signal at the frequency of vibration, an oscillator for generating a reference signal at a predetermined frequency, a mixing or multiplying device connected to the pick-up and oscillator for combining the said signals to produce signals at the sum and difference frequencies, a low-pass filter connected to the mixing or multiplying device and arranged to discriminate against the signal of the sum frequency and to pass the signal of the difference frequency, and an indicating instrument connected to the lowpass filter to respond to the signal of the difference frequency.
2. Apparatus as claimed in claim 1 wherein the frequency of the oscillator signal is higher than the frequency of the pick-up signal.
3. Apparatus as claimed in claim 1 or 2 wherein the indicating instrument includes a peak detector responsive to the signal of the difference frequency.
4. Apparatus as claimed in any preceding claim wherein the oscillator is tunable to adjust the frequency of the reference signal.
5. Apparatus for detecting faults or defects in moving machine parts substantially as herein described with reference to and as shown in the accompanying drawing.
GB15968/78A 1977-04-21 1978-04-21 Apparatus for detecting faults or defects in moving machine parts Expired GB1603190A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7704347A NL7704347A (en) 1977-04-21 1977-04-21 DETECTION SYSTEM AND THE DETECTION DEVICE IN WHICH THE SYSTEM IS INSTALLED.

Publications (1)

Publication Number Publication Date
GB1603190A true GB1603190A (en) 1981-11-18

Family

ID=19828408

Family Applications (1)

Application Number Title Priority Date Filing Date
GB15968/78A Expired GB1603190A (en) 1977-04-21 1978-04-21 Apparatus for detecting faults or defects in moving machine parts

Country Status (7)

Country Link
JP (1) JPS53132394A (en)
DE (1) DE2817625C2 (en)
FR (1) FR2388274A1 (en)
GB (1) GB1603190A (en)
IT (1) IT1112653B (en)
NL (1) NL7704347A (en)
SE (1) SE438047C (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0227138A1 (en) * 1985-11-28 1987-07-01 SKF Industrial Trading & Development Co, B.V. Means for detecting faults or defects in moving machine parts
GB2209397A (en) * 1987-10-02 1989-05-10 Servo Corp Of America Acoustic detection of bearing defects
US5679900A (en) * 1992-12-08 1997-10-21 Skf Condition Monitoring Envelope enhancement system for detecting paper machine press section anomalous vibration measurements

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU949342A1 (en) * 1977-12-05 1982-08-07 Специальное Опытное Проектно-Конструкторско-Технологическое Бюро Сибирского Отделения Всесоюзной Ордена Ленина Академии Сельскохозяйственных Наук Им.В.И.Ленина Method and device for detecting flaws in cyclic action objects
JPS5653422A (en) * 1979-10-08 1981-05-13 Hitachi Ltd Diagnosis device for bearing abnormality
DE3049628C2 (en) * 1980-12-31 1982-10-21 Basf Ag, 6700 Ludwigshafen Method for monitoring the formation and progression of cracks in machine parts and components as well as a device for carrying out the method
RU2495395C1 (en) * 2012-04-27 2013-10-10 Федеральное государственное унитарное предприятие "Научно-производственный центр газотурбостроения "Салют" Method of diagnosing twin-shaft gas turbine engine transmission

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE881836C (en) * 1951-02-09 1953-07-02 Kurt Dr Bruecker-Steinkuhl Frequency analyzer based on the search tone analysis method for coarse and fine analysis
DE1077444B (en) * 1957-04-24 1960-03-10 Rohde & Schwarz Arrangement for the analysis of vibrations
US3393557A (en) * 1967-06-29 1968-07-23 Texaco Inc Apparatus for measuring selected engine vibration characteristics
US3971249A (en) * 1975-03-28 1976-07-27 Sun Oil Company Of Pennsylvania Mechanical testing system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0227138A1 (en) * 1985-11-28 1987-07-01 SKF Industrial Trading & Development Co, B.V. Means for detecting faults or defects in moving machine parts
US4768380A (en) * 1985-11-28 1988-09-06 Skf Engineering & Research Centre, B.V. Method and means for detecting faults or defects in moving machine parts
GB2209397A (en) * 1987-10-02 1989-05-10 Servo Corp Of America Acoustic detection of bearing defects
GB2209397B (en) * 1987-10-02 1991-12-11 Servo Corp Of America On-line acoustic detection of bearing defects
US5679900A (en) * 1992-12-08 1997-10-21 Skf Condition Monitoring Envelope enhancement system for detecting paper machine press section anomalous vibration measurements

Also Published As

Publication number Publication date
DE2817625C2 (en) 1986-03-27
SE7804165L (en) 1978-10-22
JPS53132394A (en) 1978-11-18
DE2817625A1 (en) 1978-10-26
SE438047C (en) 1987-04-05
NL7704347A (en) 1978-10-24
SE438047B (en) 1985-03-25
IT7819760A0 (en) 1978-01-30
IT1112653B (en) 1986-01-20
FR2388274B1 (en) 1984-09-14
FR2388274A1 (en) 1978-11-17

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930421