US3636441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of measuring crack depths in electrically conductive metal workpieces using current probes with voltage probes located between current probes by measuring the minimum potential difference between the voltage and current probes
Assignee: Mitsubishi Heavy Industries Ltd
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Filing: 1970-02-19
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Granted: 1972-01-18
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Expires: 1990-02-19
Abstract
Abstract A method for determining in a nondestructive manner the existence, the depth and the length of cracks in an electrically conductive metal workpiece such as a steel plate or a steel pipe, by means of an electric resistance measurement which is carried out by using a pair of current probes and a pair of voltage probes located between the current probes, and, if a defect is located between the current probes and the voltage probes, the measurement is made on the basis of the minimum potential difference detected by the voltage probes rather than by the maximum value in the measured voltage distribution.
Inventors
- 👤 Tsutomu Fujimura
- 👤 Hiroshi Kamata
- 👤 Tomio Yamaguchi
- 👤 Hisanobu Fukue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:10
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/14; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/20
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
93 words
A method for measuring defects in an electrically conductive workpiece using an electrical resistance measurement wherein a pair of voltage probes are employed between a pair of current probes which are connected to a source of direct current and applied to the workpiece to be measured, comprising applying the current through the current probes to the workpiece to be measured and, when a defect is located by the current probes and the voltage probes, making a measurement of the voltage on the basis of the minimum potential difference detected by the voltage probes.
Claim 2
Independent Claim
93 words
A method for measuring defects in an electrically conductive workpiece using an electrical resistance measurement wherein a pair of voltage probes are employed between a pair of current probes which are connected to a source of direct current and applied to the workpiece to be measured, comprising applying the current through the current probes to the workpiece to be measured and, when a defect is located by the current probes and the voltage probes, making a measurement of the voltage on the basis of the minimum potential difference detected by the voltage probes.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |