US3737978A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brazing method
Assignee: Aeronca Inc
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Filing: 1971-05-05
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Granted: 1973-06-12
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Expires: 1991-05-05
Abstract
Abstract A method and apparatus are disclosed for brazing articles such as honeycomb sandwich structures. The apparatus includes a cold wall box-like housing separable into upper and lower sections. Each section carries a ceramic die member provided with passageways terminating in small ports for conducting a cooling fluid adjacent to the work. The workpiece is heated by electrical resistance heater strips passing above and below the workpiece. Means are provided for evacuating the housing and back-filling it with argon. When the workpiece is brought to brazing temperature, two expandable bags are inflated. One bag raises the lower die section to form a general fit with the upper one. The second bag is in direct contact with the upper face of the workpiece and exerts a uniform pressure normal to its surface. After brazing, the bags are deflated and chilled argon is introduced through the die passages to cool the work. Other features include localized temperature control by electron emission or cooling tubes and vapor removal by means of a cold trap.
Inventors
- 👤 R Rathbun
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:54
CPC Classifications
B; B23; B23K; B23K1/00; B23K1/0008; B23K1/0014
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
190 words
The method of brazing a honeycomb core sandwich member comprising the steps of, disposing a sandwich member to be brazed on a lower die member, disposing an upper die member above said sandwich member, interposing resistance heating elements intermediate said sandwich member and said die members, enclosing the die members and said sandwich member in an airtight enclosure the die members and Sandwich member being exposed to the same enveronmental conditions within said enclosure, heating said sandwich member by means of said resistance heaters to an elevated temperature below brazing temperature, evacuating said enclosure, back-filling said enclosure with an inert gas at a pressure less than atmospheric while said sandwich is at said elevated temperature, thereafter raising the temperature of said sandwich member to brazing temperature by means of said resistance heating elements, shifting said first die member toward said second die member, applying a compressive force normal to the surface of said sandwich member, and thereafter cooling said sandwich member by flowing a cooling gas through passageways in each of said die members and flowing said cooling gas outwardly through openings in the working faces of said die members.
Claim 2
Independent Claim
190 words
The method of brazing a honeycomb core sandwich member comprising the steps of, disposing a sandwich member to be brazed on a lower die member, disposing an upper die member above said sandwich member, interposing resistance heating elements intermediate said sandwich member and said die members, enclosing the die members and said sandwich member in an airtight enclosure the die members and Sandwich member being exposed to the same enveronmental conditions within said enclosure, heating said sandwich member by means of said resistance heaters to an elevated temperature below brazing temperature, evacuating said enclosure, back-filling said enclosure with an inert gas at a pressure less than atmospheric while said sandwich is at said elevated temperature, thereafter raising the temperature of said sandwich member to brazing temperature by means of said resistance heating elements, shifting said first die member toward said second die member, applying a compressive force normal to the surface of said sandwich member, and thereafter cooling said sandwich member by flowing a cooling gas through passageways in each of said die members and flowing said cooling gas outwardly through openings in the working faces of said die members.
Claim 3
Dependent Claim
29 words
The method of claim 1 in which said compressive force is applied by inflating an expandable bag member interposed between said sandwich structure and one of said die members.
Claim 4
Dependent Claim
35 words
The method of claim 1 comprising the further step of maintaining a substantially uniform temperature in said brazing structure by effecting localized cooling of the resistance heating means at one end of said sandwich structure.
Claim 5
Dependent Claim
30 words
The method of claim 3 in which the localized cooling is effected by creating a flow of cooling water adjacent to the resistance heating means, whereby heat is radiated therefrom.
Claim 6
Dependent Claim
40 words
The method of claim 1 in which said die members are separated during the introduction of said cooling gas and said sandwich structure is forced from said lower die by said cooling gas and is surrounded by said cooling gas.
Claim 7
Dependent Claim
47 words
The method of claim 1 in which vapor is removed from said brazing environment by exposing the gas forming said environment to a cold surface remote from said sandwich structure, whereby said vapor is condensed on said cold surface and is held remote from said sandwich structure.
Claim 8
Independent Claim
176 words
The method of brazing a honeycomb core sandwich member comprising the steps of, disposing a sandwich member to be brazed on a lower die member, disposing an upper die member above said sandwich member, interposing resistance heating elements intermediate said sandwich member and said die members, enclosing the die members and said sandwich member In an airtight enclosure the die members and Sandwich member being exposed to the same enveronmental conditions within said enclosure, heating said sandwich member by means of said resistance heaters to an elevated temperature below brazing temperature, evacuating said enclosure, back-filling said enclosure with an inert gas at a pressure less than atmospheric while said sandwich is at said elevated temperature, thereafter raising the temperature of said sandwich member to brazing temperature by means of said resistance heating elements, applying a compressive force to said sandwich member, and thereafter cooling said sandwich member by flowing a cooling gas through passageways in each of said die members and flowing said cooling gas outwardly through openings in the working faces of said die members.
Claim 9
Independent Claim
176 words
The method of brazing a honeycomb core sandwich member comprising the steps of, disposing a sandwich member to be brazed on a lower die member, disposing an upper die member above said sandwich member, interposing resistance heating elements intermediate said sandwich member and said die members, enclosing the die members and said sandwich member In an airtight enclosure the die members and Sandwich member being exposed to the same enveronmental conditions within said enclosure, heating said sandwich member by means of said resistance heaters to an elevated temperature below brazing temperature, evacuating said enclosure, back-filling said enclosure with an inert gas at a pressure less than atmospheric while said sandwich is at said elevated temperature, thereafter raising the temperature of said sandwich member to brazing temperature by means of said resistance heating elements, applying a compressive force to said sandwich member, and thereafter cooling said sandwich member by flowing a cooling gas through passageways in each of said die members and flowing said cooling gas outwardly through openings in the working faces of said die members.
Claim 10
Independent Claim
220 words
The method of brazing a honeycomb core sandwich member and shaping said core to a final configuration comprising the steps of, disposing a sandwich member to be brazed on a lower die member, the sandwich member being of a configuration other than the final configuration, disposing an upper die member above said sandwich member, interposing resistance heating elements intermediate said sandwich member and said die members, enclosing the die members and said sandwich member in an airtight enclosure the die members and Sandwich member being exposed to the same enveronmental conditions within said enclosure, heating said sandwich member by means of said resistance heaters to an elevated temperature below brazing temperature, evacuating said enclosure, back-filling said enclosure with an inert gas at a pressure less than atmospheric while said sandwich is at said elevated temperature, thereafter raising the temperature of said sandwich member to brazing temperature by means of said resistance heating elements, shifting said first die member toward said second die member, applying a compressive force normal to the surface of said sandwich member to creep form the sandwich member to its final configuration, and thereafter cooling said sandwich member by flowing a cooling gas through passageways in each of said die members and flowing said cooling gas outwardly through openings in the working faces of said die members.
Claim 11
Independent Claim
220 words
The method of brazing a honeycomb core sandwich member and shaping said core to a final configuration comprising the steps of, disposing a sandwich member to be brazed on a lower die member, the sandwich member being of a configuration other than the final configuration, disposing an upper die member above said sandwich member, interposing resistance heating elements intermediate said sandwich member and said die members, enclosing the die members and said sandwich member in an airtight enclosure the die members and Sandwich member being exposed to the same enveronmental conditions within said enclosure, heating said sandwich member by means of said resistance heaters to an elevated temperature below brazing temperature, evacuating said enclosure, back-filling said enclosure with an inert gas at a pressure less than atmospheric while said sandwich is at said elevated temperature, thereafter raising the temperature of said sandwich member to brazing temperature by means of said resistance heating elements, shifting said first die member toward said second die member, applying a compressive force normal to the surface of said sandwich member to creep form the sandwich member to its final configuration, and thereafter cooling said sandwich member by flowing a cooling gas through passageways in each of said die members and flowing said cooling gas outwardly through openings in the working faces of said die members.
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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) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |