US3987219A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for impregnation of wood by pressure surges during immersion
Assignee: Individual
•
Filing: 1973-09-20
•
Granted: 1976-10-19
•
Expires: 1993-09-20
Abstract
Abstract Unit loads of wood, surrounded by a small quantity of liquid, are impregnated in sturdy vessels provided with a cover. After or during an impregnation period under vacuum, the impregnation is completed by subjecting the liquid and the wood to pressure surges or impacts of such an intensity that the wood is deformed in the direction of length of the fibers or in the radial or tangential direction thereof within a range between the average pressure causing breakdown of the wood material and one-third of that average pressure. Intensity of pressure surges increases as the vessels are filled with impregnation liquid. Pressure waves may be produced by means of either compressed air, steam or explosive gas. A connecting chamber is provided for preparation and storage of the impregnation liquid.
Inventors
- 👤 Ewald Arvidsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 09:23
CPC Classifications
B; B27; B27K; B27K3/00; B27K3/02; B27K3/08; B27K3/083
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
121 words
A method for impregnation of wood in which wood immersed in an impregnation liquid is subjected to pressure steps starting with atmospheric pressure after vacuum treatment evacuating air from the wood cells, the impregnating liquid being absorbed by the wood upon an increase in pressure, characterized in that the wood immersed in said liquid is subjected to short increasing pressure surges of a duration substantially less than one second, the maximum intensity of said pressure surges being such that the wood is compressed to a pressure in the range from one third of the breakdown pressure of the wood to the breakdown pressure of the wood, each such pressure surge being followed by a recovery to equilibrium at substantially atmospheric pressure.
Claim 2
Independent Claim
121 words
A method for impregnation of wood in which wood immersed in an impregnation liquid is subjected to pressure steps starting with atmospheric pressure after vacuum treatment evacuating air from the wood cells, the impregnating liquid being absorbed by the wood upon an increase in pressure, characterized in that the wood immersed in said liquid is subjected to short increasing pressure surges of a duration substantially less than one second, the maximum intensity of said pressure surges being such that the wood is compressed to a pressure in the range from one third of the breakdown pressure of the wood to the breakdown pressure of the wood, each such pressure surge being followed by a recovery to equilibrium at substantially atmospheric pressure.
Claim 3
Dependent Claim
19 words
A method as defined in claim 1, in which the duration of said pressure surges is about 0.001 second.
Claim 4
Dependent Claim
82 words
A method as defined in claim 1, in which the wood immersed in said liquid is subjected to said short pressure surges while said wood and said liquid are contained in a massive container and said pressure surges are initiated at one wall of said container so as to propagate towards and be reflected from an opposite wall thereof, and in which recovery to equilibrium as aforesaid is initiated by the pressure surge reaching a release valving device provided on said container.
Claim 5
Dependent Claim
27 words
A method according to claim 1, characterized in that the pressure surges are oriented so as to propagate along the direction of the fibers of the wood.
Claim 6
Dependent Claim
30 words
A method according to claim 1, characterized in that the pressure surges are oriented so as to propagate at right angles to the direction of the fibers of the wood.
Claim 7
Dependent Claim
36 words
A method according to claim 1, characterized in that the pressure surges are oriented so as to propagate both along the direction of the fibers of the wood and at right angles to said fiber direction.
Claim 8
Dependent Claim
36 words
A method according to claim 6, characterized in that the wood is subjected simultaneously to pressure surges in the direction of the fibers of the wood and pressure surges at right angles to said fiber direction.
Claim 9
Dependent Claim
21 words
A method according to claim 7, characterized in that the intensity of the pressure surges is the same in both directions.
Claim 10
Dependent Claim
20 words
A method according to claim 6, characterized in that the wood is subjected to alternate pressure surges in different directions.
Claim 11
Dependent Claim
23 words
A method according to claim 1, characterized in that the pressure surges are generated by pressurized air suddenly introduced into the impregnation liquid.
Claim 12
Dependent Claim
22 words
A method according to claim 1, characterized in that the pressure surges are generated by steam suddenly introduced into the impregnation liquid.
Claim 13
Dependent Claim
20 words
A method according to claim 1, characterized in that the pressure surges are generated by detonation of an explosive gas.
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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) | 1979-10-19 | 1980-04-19 | 1980-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-19 | 1984-04-19 | 1984-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-19 | 1988-04-19 | 1988-10-19 | $7700.00 | Window Closed / Lapsed |