US4430896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for detecting crack produced in workpiece in distortion removal processing
Assignee: Toyota Motor Corp
•
Filing: 1982-03-24
•
Granted: 1984-02-14
•
Expires: 2002-03-24
Abstract
Abstract An apparatus for detecting cracks possibly produced in a workpiece whose distortion is being removed under pressure exerted by a pressing rod of a distortion removing machine. A detection signal produced by a sensor embedded in the pressing rod during a first predetermined period is compared with a first predetermined signal level for determining whether or not the cracking occurs in the workpiece. A detection signal produced by the acoustic emission sensor during a second predetermined period in which the workpiece is subjected to the pressure of the pressing rod without involving cracks is compared with a second predetermined signal level to determine whether or not the detecting apparatus itself operates normally.
Inventors
- 👤 Kazuo Fujimori
- 👤 Akira Banno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:04
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/22; G01N29/30; G01N29/14
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
151 words
A method of detecting cracks produced in a workpiece when the workpiece is processed so that the distortion thereof is mechanically removed comprising steps of: setting a first period in which an acoustic emission signal is produced due to cracks possibly produced in the workpiece in the course of processing for mechanically removing the distortion and a second period in which an acoustic emission signal is produced due to causes other than said cracks; determining occurrence or non-occurrence of said cracks by comparing an acoustic emission signal produced during said first period with a first predetermined value, said acoustic emission signal being contained in an output signal produced by an acoustic emission signal detecting sensor embedded in a portion of a distortion removing machine; and diagnosing whether or not the crack detecting system operates properly by comparing the acoustic emission signal produced during said second period with a second predetermined value.
Claim 2
Independent Claim
151 words
A method of detecting cracks produced in a workpiece when the workpiece is processed so that the distortion thereof is mechanically removed comprising steps of: setting a first period in which an acoustic emission signal is produced due to cracks possibly produced in the workpiece in the course of processing for mechanically removing the distortion and a second period in which an acoustic emission signal is produced due to causes other than said cracks; determining occurrence or non-occurrence of said cracks by comparing an acoustic emission signal produced during said first period with a first predetermined value, said acoustic emission signal being contained in an output signal produced by an acoustic emission signal detecting sensor embedded in a portion of a distortion removing machine; and diagnosing whether or not the crack detecting system operates properly by comparing the acoustic emission signal produced during said second period with a second predetermined value.
Claim 3
Independent Claim
126 words
An apparatus for detecting cracks produced in a workpiece when the workpiece is processed so that the distortion thereof is mechanically removed, which comprises: a sensor receiving an acoustic emission signal from the workpiece and embedded in a particular portion of a distortion removing machine; and a detector circuit responsive to the output of said sensor to compare the output of said sensor with a first and second reference value, representative, respectively, of non-occurrence of cracking, and acoustic emission signals due to causes other than cracking of the workpiece, to provide a detection signal indicative of occurrence of the cracks when the output of said sensor exceeds both of said first and second reference values and the distortion removing machine exerts a pressure to the workpiece.
Claim 4
Independent Claim
126 words
An apparatus for detecting cracks produced in a workpiece when the workpiece is processed so that the distortion thereof is mechanically removed, which comprises: a sensor receiving an acoustic emission signal from the workpiece and embedded in a particular portion of a distortion removing machine; and a detector circuit responsive to the output of said sensor to compare the output of said sensor with a first and second reference value, representative, respectively, of non-occurrence of cracking, and acoustic emission signals due to causes other than cracking of the workpiece, to provide a detection signal indicative of occurrence of the cracks when the output of said sensor exceeds both of said first and second reference values and the distortion removing machine exerts a pressure to the workpiece.
Claim 5
Dependent Claim
38 words
An apparatus according to claim 2 wherein said sensor is inserted in a hole formed in a pressing rod of the distortion removing machine and applied with a constant pressure from a spring supported by a sensor holder.
Claim 6
Dependent Claim
38 words
An apparatus according to claim 2 wherein said sensor is inserted in a hole formed in a support table of the distortion removing machine and applied with a constant pressure from a spring supported by a sensor holder.
Claim 7
Dependent Claim
260 words
An apparatus according to claim 2 wherein said detector circuit includes: a first comparator comparing the output of said sensor with a first reference value to produce a first comparison signal when the sensor output exceeds the first reference value; a second comparator comparing the output of said sensor with a second reference value to produce a second comparison signal when the sensor output exceeds the second reference value; a limit switch operable to be closed during the time when said distortion removing machine continues to exert a pressure to the workpiece; a first gate circuit passing the output of said first comparator when said limit switch is maintained to be closed; a second gate circuit passing the output of said second comparator when said limit switch is maintained to be closed; a first counter receiving the output pulse signal of said first comparator through said first gate circuit to provide a first count signal; a second counter receiving the output pulse signal of said second comparator through said second gate circuit to provide a second count signal; a third gate circuit passing the first count signal when said limit switch is maintained to be closed; a fourth gate circuit passing the second count signal when said limit switch is maintained to be closed; a first display responsive to the output of said third gate circuit to selectively display the absence of cracks and the failure of the detector itself; and a second display responsive to the output signal of said fourth gate circuit to display the occurrence of cracks.
References Cited (Backward Citations)
US4036057A
Cited
US4344326A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-13 | 1987-08-15 | 1988-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-13 | 1991-08-15 | 1992-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-13 | 1995-08-15 | 1996-02-14 | $7700.00 | Window Closed / Lapsed |