US4127788A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Piezoelectric stress indicator for mine roofs
Assignee: Individual
•
Filing: 1977-07-08
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Granted: 1978-11-28
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Expires: 1997-07-08
Abstract
Abstract A device for detecting deformations in mine roofs wherein an open cylindrical casing having inner and outer threaded surfaces is threaded into the mine roof. A piezoelectric crystal is mounted within the casing to sense the deformations and stresses in the mine roof. Provision is made for mounting a plurality of piezoelectric crystals within the casing whereby stresses at varying locations are sensible.
Inventors
- 👤 Ralph N. Daugherty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:22
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/06; B06B1/0644; G; G01; G01L; G01L1/00; G01L1/16; G01L5/00; G01L5/24; G01V; G01V1/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
141 words
A device for detecting deformation in rock strata comprising: an open cylindrical casing having an inner threaded surface and an outer surface insertable in the strata; external screw threads on said outer surface to rigidly couple said outer surface to the strata in which said casing is inserted; a piezoelectric crystal stress sensor; a block of resinous material in which said sensor is embedded, said block having external threads to rigidly couple said stress sensor to the inner surface of said casing to transmit deformation of said strata to said stress sensing means and to permit said stress sensor to be coupled to said casing after insertion of said casing in said solid; and spacer means to axially locate said stress sensor within said casing, said spacer means comprising a solid cylinder threadedly engaged with said inner surface of said casing.
Claim 2
Independent Claim
141 words
A device for detecting deformation in rock strata comprising: an open cylindrical casing having an inner threaded surface and an outer surface insertable in the strata; external screw threads on said outer surface to rigidly couple said outer surface to the strata in which said casing is inserted; a piezoelectric crystal stress sensor; a block of resinous material in which said sensor is embedded, said block having external threads to rigidly couple said stress sensor to the inner surface of said casing to transmit deformation of said strata to said stress sensing means and to permit said stress sensor to be coupled to said casing after insertion of said casing in said solid; and spacer means to axially locate said stress sensor within said casing, said spacer means comprising a solid cylinder threadedly engaged with said inner surface of said casing.
Claim 3
Dependent Claim
54 words
The device of claim 1 further comprising a second stress sensor and a second block of resinous material in which said second stress sensor is embedded, said second block having external threads to rigidly couple said second stress sensor to said casing in a position spaced from said first sensor by said spacer means.
Claim 4
Dependent Claim
24 words
The device of claim 2 wherein said spacer means includes an axial channel to provide a passage for electrical connections to said stress sensor.
Claim 5
Dependent Claim
31 words
The device of claim 1 wherein said block of resinous material further comprises a head portion for covering one end of said casing, said head portion consisting of said resinous material.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-11-27 | 1982-05-29 | 1982-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-27 | 1986-05-29 | 1986-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-27 | 1990-05-29 | 1990-11-28 | $7700.00 | Window Closed / Lapsed |