US4942387A
Expired / Lapsed
US
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Apparatus and method for tool break and wear detection
Assignee: General Electric Co
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Filing: 1989-09-05
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Granted: 1990-07-17
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Expires: 2009-09-05
Abstract
Abstract A device for determining cutting tool wear and breakage has an accelerometer for sensing tool vibrations. Functions of the AC and DC power of the vibration signal, such as the powers themselves or the square root of the powers, are computed and compared. If the relationship between the AC and DC power changes beyond selected limits, an alarm is sounded or flashed. A method for determining cutting tool wear and breakage provides a tool vibration signal, computes functions of the AC and DC power of the vibration signal, and compares the AC and DC power signals.
Inventors
- 👤 Charles E. Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:02
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/406; G05B19/4065; B; B23; B23Q; B23Q17/00; B23Q17/09; B23Q17/0952; B23Q17/0957; B23Q17/0971
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
77 words
Apparatus for determining the condition of a tool, said apparatus comprising: means for sensing the vibration of the tool to provide a vibration signal having AC and DC power components; means for computing a first signal that is a function of said DC power component of said vibration signal; means for computing a second signal that is a function of said AC power component of said vibration signal; and means for comparing said first and second signals.
Claim 2
Dependent Claim
77 words
Apparatus for determining the condition of a tool, said apparatus comprising: means for sensing the vibration of the tool to provide a vibration signal having AC and DC power components; means for computing a first signal that is a function of said DC power component of said vibration signal; means for computing a second signal that is a function of said AC power component of said vibration signal; and means for comparing said first and second signals.
Claim 3
Dependent Claim
12 words
The apparatus of claim 1 wherein said sensing means comprises an accelerometer.
Claim 4
Dependent Claim
15 words
The apparatus of claim 1 wherein said first signal is proportional to said DC power.
Claim 5
Dependent Claim
19 words
The apparatus of claim 1 wherein said first signal is proportional to the square root of said DC power.
Claim 6
Dependent Claim
15 words
The apparatus of claim 1 wherein said second signal is proportional to said AC power.
Claim 7
Dependent Claim
19 words
The apparatus of claim 1 wherein said second signal is proportional to the square root of said AC power.
Claim 8
Dependent Claim
54 words
The apparatus of claim 1 wherein said comparison means comprises means for forming a ratio of said first and second signals, means for forming an average value of said ratio, means for comparing said ratio to said average value of said ratio, and means for comparing said average value to a selected threshold value.
Claim 9
Dependent Claim
45 words
The apparatus of claim 1 further comprising a band pass filter coupled to said sensing means, an energy detector coupled to said filter, and an analog-to-digital converter having an input coupled to said energy detector and an output coupled to both of said computing means.
Claim 10
Dependent Claim
19 words
The apparatus of claim 8 wherein said band pass filter has a passband between about 30 to 70 KHz.
Claim 11
Dependent Claim
23 words
The apparatus of claim 8 wherein said energy detector comprises a full wave rectifier and a low pass filter coupled to said rectifier.
Claim 12
Dependent Claim
18 words
The apparatus of claim 10 wherein said low pass filter has a cut-off frequency of about 500 Hz.
Claim 13
Dependent Claim
14 words
The apparatus of claim 1 further comprising an alarm coupled to said comparison means.
Claim 14
Dependent Claim
37 words
The apparatus of claim 1 wherein said first signal computing means comprises means for forming a sum of a selected number of samples of said vibration signal, and means for dividing said sum by said selected number.
Claim 15
Dependent Claim
53 words
The apparatus of claim 1 wherein said first signal computing means comprises means for forming a first product of a first selected constant and a current sample value, means for forming a second product of a second selected constant and a prior sample average, and means for summing said first and second products.
Claim 16
Dependent Claim
17 words
The apparatus of claim 14 wherein said first and second constants are about 0.2 and 0.8, respectively.
Claim 17
Independent Claim
60 words
A method for determining the condition of a tool, said method comprising: providing a vibration signal by sensing the tool vibration; computing a first signal that is a function of the DC power of said vibration signal; computing a second signal that is a function of the AC power of said vibration signal; and comparing said first and second signals.
Claim 18
Independent Claim
60 words
A method for determining the condition of a tool, said method comprising: providing a vibration signal by sensing the tool vibration; computing a first signal that is a function of the DC power of said vibration signal; computing a second signal that is a function of the AC power of said vibration signal; and comparing said first and second signals.
Claim 19
Dependent Claim
15 words
The method of claim 16 wherein said first signal is proportional to said DC power.
Claim 20
Dependent Claim
19 words
The method of claim 16 wherein said first signal is proportional to the square root of said DC power.
Claim 21
Dependent Claim
15 words
The method of claim 16 wherein said second signal is proportional to said AC power.
Claim 22
Dependent Claim
19 words
The method of claim 16 wherein said second signal is proportional to the square root of said AC power.
Claim 23
Dependent Claim
46 words
The method of claim 16 wherein said comparing step comprises forming a ratio of said first and second signals, forming an average value of said ratio, comparing said ratio to said average value of said ratio, and comparing said average value to a selected threshold value.
Claim 24
Dependent Claim
10 words
The method of claim 16 further comprising actuating an alarm.
Claim 25
Dependent Claim
33 words
The method of claim 16 wherein said first signal computing step comprises forming a sum of a selected number of samples of said vibration signal, and dividing said sum by said selected number.
Claim 26
Dependent Claim
47 words
The method of claim 16 wherein said first signal computing step comprises forming a first product of a first selected constant and a current sample value, forming a second product of a second selected constant and a prior sample average, and summing the first and second products.
References Cited (Backward Citations)
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