US3612813A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming a lightweight metal sandwich having a honeycomb core
Assignee: RTX Corp
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Filing: 1970-04-29
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Granted: 1971-10-12
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Expires: 1990-04-29
Abstract
Abstract A sheet of honeycomb sandwich structure having flat exterior surfaces and internal cooling passages is constructed by the electric-resistance welding of outer sheets of flat metal to a center core of corrugated metal. The resistance welds are accomplished using electrically conductive shunt bars which have a contact area proportioned to provide a current density of sufficient intensity to cause a local heating and fusion between the corrugated metal and the flat metal sheet.
Inventors
- 👤 Francis C Gerath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:53
CPC Classifications
B; B23; B23K; B23K11/00; B23K11/002; B23K11/0093; B21; B21D; B21D47/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
321 words
A method of welding flat sheets of metal to corrugated sheet metal by continuous-weld seams to form rigid lightweight structures having smooth exterior surfaces and a honeycomb core wherein shunt bars are located between the flat and the corrugated sheets to provide paths for electric current through the core and to resist crushing of the core during welding comprising: placing a corrugated core sheet in juxtaposition with a first flat outer sheet to form a subunit; inserting into each enclosure formed between said corrugated sheet and said first flat sheet a trapezoidal-shaped bar which acts as an electrical shunt and also resists crushing of the surrounding enclosure curing welding, with the smaller of the parallel surfaces of said trapezoid adjacent to said corrugated sheet; moving thE subunit between a pair of first electrodes which applies a compressive force to the subunit, one of said pair of electrodes having a smooth surface and contacting said flat over a span of several adjacent weld seams, the other of said pair of electrodes having ridges along the surface thereof, said ridges being tapered and aligned to fit into accessible depressions in said corrugated sheet; passing a first electric current between said first electrodes sufficient to cause continuous-weld seams between said corrugated sheet and said flat sheet in regions adjacent to said ridges; placing a second flat outer sheet over the exposed side of the corrugated sheet of the subunit to form a unit; moving said unit between a pair of second electrodes, which span several adjacent weld seams and applies a compressive force to the unit, each one of said pair of second electrodes having a smooth surface and contacting said upper and lower flat sheets respectively; passing a second electric current between said second electrodes sufficient to cause continuous-weld seams between said corrugated and said flat sheets in a region adjacent to said shunt bars; and removing said shunt bars from said structure.
Claim 2
Independent Claim
321 words
A method of welding flat sheets of metal to corrugated sheet metal by continuous-weld seams to form rigid lightweight structures having smooth exterior surfaces and a honeycomb core wherein shunt bars are located between the flat and the corrugated sheets to provide paths for electric current through the core and to resist crushing of the core during welding comprising: placing a corrugated core sheet in juxtaposition with a first flat outer sheet to form a subunit; inserting into each enclosure formed between said corrugated sheet and said first flat sheet a trapezoidal-shaped bar which acts as an electrical shunt and also resists crushing of the surrounding enclosure curing welding, with the smaller of the parallel surfaces of said trapezoid adjacent to said corrugated sheet; moving thE subunit between a pair of first electrodes which applies a compressive force to the subunit, one of said pair of electrodes having a smooth surface and contacting said flat over a span of several adjacent weld seams, the other of said pair of electrodes having ridges along the surface thereof, said ridges being tapered and aligned to fit into accessible depressions in said corrugated sheet; passing a first electric current between said first electrodes sufficient to cause continuous-weld seams between said corrugated sheet and said flat sheet in regions adjacent to said ridges; placing a second flat outer sheet over the exposed side of the corrugated sheet of the subunit to form a unit; moving said unit between a pair of second electrodes, which span several adjacent weld seams and applies a compressive force to the unit, each one of said pair of second electrodes having a smooth surface and contacting said upper and lower flat sheets respectively; passing a second electric current between said second electrodes sufficient to cause continuous-weld seams between said corrugated and said flat sheets in a region adjacent to said shunt bars; and removing said shunt bars from said structure.
Claim 3
Dependent Claim
89 words
The method according to claim 1 in which said pair of first electrodes is maintained at an electrical potential difference of approximately 3 volts, apply a compressive force of 200 pounds on said subunit moving therebetween and pass a welding current of 8, 200 amperes through said subunit, and said pair of second electrodes is maintained at an electrical potential difference of approximately 3 volts, apply a compressive force of 225 pounds on said unit passing therebetween and pass a welding current of 10, 200 amperes through said unit.
Claim 4
Dependent Claim
65 words
The method according to claim 1 including, before the step of moving the unit between a pair of second electrodes, placing a current-carrier bar between said unit and the electrode adjacent therewith to more uniformly distribute the second electric current throughout the unit assembly as electric current passes between the electrodes thereby improving the weld and avoiding sticking of the shunt to the adjacent sheets.
Claim 5
Dependent Claim
21 words
The method according to claim 1 wherein at least one of the welds is made up of discrete individual overlapping welds.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |