US3609624A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Strain gage and method of bonding the gage to a member under test
Assignee: Vishay Intertechnology Inc
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Filing: 1969-02-20
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Granted: 1971-09-28
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Expires: 1989-02-20
Abstract
Abstract A strain gage of the electrical resistance type is disclosed herein which has improved adhesive means to attaching the gage to a member under test. The adhesive is applied to the gage at the time of manufacture and includes a thermosetting adhesive composition which is substantially nontacky at room temperature, and upon heating to a first elevated temperature wets the surface of the test piece in contact therewith and when heated to a second higher temperature, is converted to the infusible, insoluble state.
Inventors
- 👤 Bella Nagy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:25
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/20; G01L1/22; G01L1/2287
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
34 words
The strain gage as defined in claim 1 in which said adhesive composition contains from about four to about 10 parts by weight of boron trifluoride-monoethanol complex per 100 parts of epoxylated cresol-formaldehyde resin.
Claim 2
Dependent Claim
190 words
In a strain gage of the electrical resistance type adapted to be attached to a member under test comprising an electrically conductive filament resistively responsive to strain applied thereto, the improvement of which is comprised of: a film of a thermosetting adhesive composition on the exposed surface of said filament for bonding the filament to the member under test; said film being comprised of a mixture of a first epoxy resin having a melting point at a first elevated temperature and a second epoxy resin having a melting point at a second elevated temperature relatively higher than the melting point of said first epoxy resin and being substantially nontacky and solvent-free at room temperature and a catalyst which is adapted to activate only at said second elevated temperature and convert said film into an infusible, insoluble state whereby said film upon being heated to the first elevated temperature, the low melting point epoxy resin becomes flowable to wet the surface of the member under test in contact therewith and upon being heated to the second elevated temperature the epoxy resins polymerize and become infusible, insoluble and bondable to said member.
Claim 3
Dependent Claim
46 words
The strain gage as defined in claim 3 in which said film of thermosetting adhesive composition is adapted to become fluid at a temperature in a range between 120* F. and 200* F. to wet the test member to which said gage is to be applied.
Claim 4
Dependent Claim
39 words
The strain gage as defined in claim 3 in which said relatively high melting point epoxy resin polymerizes at a temperature approximately 20* F. above the temperature at which the said relatively low melting point epoxy resin becomes fluid.
Claim 5
Independent Claim
149 words
The method of adhering a strain gage of the electrical resistance type of a member under test which includes an electrically conductive filament resistively responsive to strain applied thereto comprising the steps of: disposing a film of thermosetting adhesive composition on the exposed surface of said filament for bonding the filament to the member under test, said film being comprised of a mixture of a relatively high melting point epoxy resin, a relatively low melting point epoxy resin and a catalyst material; heating said film to a first elevated temperature whereby the low melting point epoxy reSin in said mixture becomes flowable to wet the surface of the member under test in contact therewith; and heating said film to a second elevated temperature whereby the relatively high melting point epoxy resin is caused to polymerize by the activation of said catalyst and become infusibly, insolubly bonded to said member.
Claim 6
Dependent Claim
27 words
The method as defined in claim 6 in which said film is heated to the second elevated temperature at a range between 120* F. and 200* F.
Claim 7
Dependent Claim
28 words
The method as defined in claim 6 wherein said second elevated temperature is at a temperature of approximately 20* F. above the temperature of the first elevated temperature.
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) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |