US3696499A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making a composite tube
Assignee: Texas Instruments Inc
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Filing: 1970-12-21
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Granted: 1972-10-10
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Expires: 1990-12-21
Abstract
Abstract A strip of composite metal laminate material embodying a thin inner layer of stainless steel sandwiched between and metallurgically bonded to two relatively thicker outer layers of low carbon steel is subjected to a brief, high temperature heat treatment followed by a relatively much longer heat treatment at much lower temperature for substantially eliminating the yield point in the laminate and for maximizing formability of the laminate while permitting some reduction in the corrosion resistance properties of the stainless steel layer of the laminate. The composite strip material is then readily formed into two, concentrically disposed convolutions of the strip material while the laminate material is in this highly formable condition. The convolutions of the strip material are then brazed together to provide a double-walled tubing, the brazing procedure being regulated to effect selected heat treatment of the formed composite material for substantially restoring the corrosion resistance properties of the stainless steel layer of the laminate within the finished tubing.
Inventors
- 👤 John A Dromsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:45
CPC Classifications
B; B32; B32B; B32B15/00; B32B15/01; B32B15/011
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
156 words
A method for making a double-walled tubing comprising the steps of heating a composite metal laminate material embodying a thin inner layer of austenitic stainless steel sandwiched between and metallurgically bonded to two relatively thicker outer layers of low carbon steel to a temperature in the range from about 1850*F. to about 2050* F. for a period of time in the range from about one-half to 2 minutes, heating said laminate material to a temperature in the range from about 1050*F. to about 1100*F. for a period of time in the range from about 3 to 6 hours, forming said laminate material into a double-walled tubing configuration, and brazing portions of said formed laminate material together for securing said laminate material in said tubing configuration, said formed laminate material being subjected to a temperature in the range from about 1980*F. to about 2070*F. for period of time from about one-half to 2 minutes during said brazing.
Claim 2
Dependent Claim
28 words
A method as set forth in claim 2 wherein said stainless steel layer comprises from about 2 to 25 percent of the total thickness of said laminate material.
Claim 3
Dependent Claim
30 words
A method as set forth in claim 2 wherein said stainless steel material is selected from the group consisting of Type 201, 202, 301, 302, 304 and 321 Stainless Steels.
Claim 4
Dependent Claim
34 words
A method as set forth in claim 2 wherein said low carbon steel material is selected from the group of low carbon steel materials having a maximum carbon content, by weight, of 0.13 percent.
Claim 5
Dependent Claim
55 words
A method as set forth in claim 2 wherein said laminate material is plated with coppEr prior to said forming, and wherein said formed laminate material is heated to said temperature in the range from about 1,980*F. to about 2,070*F. for melting said copper to braze said portions of said for formed laminate material together.
Claim 6
Independent Claim
166 words
A method for making a double-walled tubing comprising the steps of heating a strip of composite metal laminate material embodying a thin inner layer of Type 304 austenitic stainless steel which is sandwiched between and metallurgically bonded to two relatively thicker outer layers of Type 1008 aluminum-killed low carbon steel to a temperature in the range from about 1850*F. to about 2,005*F. for a period of time in the range from about one-half to 2 minutes, heating said laminate material to a temperature in the range from about 1,050*F. to about 1,100*F. for a period of time in the range from about 3 to 6 hours, forming said laminate material into a double-walled tubing configuration and brazing portions of said formed laminate material together for securing said laminate material in said tubing configuration, said formed laminate material being subjected to a temperature in the range from about 1,980*F. to about 2070*F. for a period of time from about one-half to 2 minutes during said brazing period.
Claim 7
Dependent Claim
76 words
A method as set forth in claim 7 wherein said laminate material is first heated to a temperature of 1,950*F. for a period of about one minute and is then heated to a temperature of about 1,100*F. for a period of about 4 hours, and wherein said formed laminate material is heated to a temperature in the range from about 2,050*F. to about 2,070*F. for a period of about 1 and 1/8 minutes during said brazing.
Claim 8
Dependent Claim
44 words
A method as set forth in claim 8 wherein said laminate material has a thickness of about 0.014 inches and wherein said stainless steel layer of said laminate material has a thickness comprising about 10 percent of the total thickness of said laminate material.
Claim 9
Dependent Claim
53 words
A method as set forth in claim 9 wherein said laminate material is plated with outer layers of copper having a thickness of about 0.00015 inches prior to said forming of said laminate material, said copper being melted during said brazing for brazing said portions of said formed laminate material to each other.
Claim 10
Dependent Claim
76 words
A method as set forth in claim 7 wherein said strip of composite metal laminate material is formed into two concentrically disposed convolutions of said strip material which are interconnected by an integral crossover portion of said strip material, and wherein said concentrically disposed convolutions of said strip material are brazed to each other with edges of said strip of laminate material being brazed to respective opposite sides of said crossover portion of said strip 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) | 1975-10-10 | 1976-04-10 | 1976-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-10 | 1980-04-10 | 1980-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-10 | 1984-04-10 | 1984-10-10 | $7700.00 | Window Closed / Lapsed |