Patent US3770044A successfully refreshed from Google Patents.
US3770044A
Expired / Lapsed
US
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Method of dewaxing shell molds
Assignee: Motors Liquidation Co
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Filing: 1972-02-07
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Granted: 1973-11-06
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Expires: 1992-02-07
Abstract
Abstract Refractory shell molds are made by a method including the steps of forming a shell investment mold over a wax pattern, freezing the mold and pattern to a temperature in the vicinity of about 100* F. whereby the pattern shrinks more than the mold to provide a slight gap between the pattern and the mold and then immediately placing the mold and pattern in a heated environment whereby the pattern is removed by melting without cracking or otherwise damaging the mold.
Inventors
- 👤 R Heath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:56
CPC Classifications
B; B22; B22C; B22C9/00; B22C9/02; B22C9/04; B22C9/043
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
139 words
The method of removing a wax pattern from a shell investment mold formed thereon, said mold having a wall thin enough to allow rapid transfer of heat therethrough and not sufficiently thick to resist breakage from the force which would result from the expansion of said wax pattern upon slow heating thereof, which comprises freezing said mold and pattern contained therein to a temperature of at lEast -80* F to create a gap between the mold and the pattern, and then immediately heating the mold and pattern in a manner such that the heat rapidly penetrates the mold wall and initially melts a surface layer of the wax pattern which expands into said gap so that the expansion forces are not sufficient to damage the mold and then completely melts the wax pattern to remove it from the mold.
Claim 2
Independent Claim
139 words
The method of removing a wax pattern from a shell investment mold formed thereon, said mold having a wall thin enough to allow rapid transfer of heat therethrough and not sufficiently thick to resist breakage from the force which would result from the expansion of said wax pattern upon slow heating thereof, which comprises freezing said mold and pattern contained therein to a temperature of at lEast -80* F to create a gap between the mold and the pattern, and then immediately heating the mold and pattern in a manner such that the heat rapidly penetrates the mold wall and initially melts a surface layer of the wax pattern which expands into said gap so that the expansion forces are not sufficient to damage the mold and then completely melts the wax pattern to remove it from the mold.
Claim 3
Independent Claim
146 words
The method of removing a wax pattern from a shell investment mold formed thereon, said mold having a wall thin enough to allow rapid transfer of heat therethrough and not sufficiently thick to resist breakage from the force which would result from the expansion of said wax pattern upon slow heating thereof, which comprises freezing said mold and pattern contained therein to a temperature of about -80* F to about -100* F to create a gap between the mold and the pattern of about 0.002 inch and then immediately heating the mold and pattern in a manner such that the heat rapidly penetrates the mold wall and initially melts a surface layer of the wax pattern which expands into said gap so that the expansion forces are not sufficient to damage the mold and then completely melts the wax pattern to remove it from the mold.
Claim 4
Independent Claim
146 words
The method of removing a wax pattern from a shell investment mold formed thereon, said mold having a wall thin enough to allow rapid transfer of heat therethrough and not sufficiently thick to resist breakage from the force which would result from the expansion of said wax pattern upon slow heating thereof, which comprises freezing said mold and pattern contained therein to a temperature of about -80* F to about -100* F to create a gap between the mold and the pattern of about 0.002 inch and then immediately heating the mold and pattern in a manner such that the heat rapidly penetrates the mold wall and initially melts a surface layer of the wax pattern which expands into said gap so that the expansion forces are not sufficient to damage the mold and then completely melts the wax pattern to remove it from the mold.
Claim 5
Independent Claim
157 words
The method of removing a wax pattern from a shell investment mold formed thereon, said mold having a wall thin enough to allow rapid transfer of heat therethrough and not sufficiently thick to resist breakage from the force which would result from the expansion of said wax pattern upon slow heating thereof, which comprises freezing said mold and pattern contained therein to a temperature of about -80* F to about -100* F to create a gap between the mold and the pattern of about 0.002 inch and then immediately heating the mold and pattern in a steam autoclave maintained at about 230* F at about 80 psi gauge so that the heat rapidly penetrates the mold wall and initially melts a surface layer of the wax pattern which expands into said gap so that the expansion forces are not sufficient to damage the mold and then completely melts the wax pattern to remove it from the mold.
Claim 6
Independent Claim
157 words
The method of removing a wax pattern from a shell investment mold formed thereon, said mold having a wall thin enough to allow rapid transfer of heat therethrough and not sufficiently thick to resist breakage from the force which would result from the expansion of said wax pattern upon slow heating thereof, which comprises freezing said mold and pattern contained therein to a temperature of about -80* F to about -100* F to create a gap between the mold and the pattern of about 0.002 inch and then immediately heating the mold and pattern in a steam autoclave maintained at about 230* F at about 80 psi gauge so that the heat rapidly penetrates the mold wall and initially melts a surface layer of the wax pattern which expands into said gap so that the expansion forces are not sufficient to damage the mold and then completely melts the wax pattern to remove it from the mold.
References Cited (Backward Citations)
GB948197A
Cited
US3512571A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |