US3600753A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential pressure forming mold assembly for forming plastic articles in a thermoplastic web
Assignee: Leesona Corp
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Filing: 1969-09-29
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Granted: 1971-08-24
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Expires: 1989-09-29
Abstract
Abstract A differential pressure forming mold wherein a sheet of deformable plastic is supported between a mold assembly having a plurality of article forming mold cavities and an opposed mold assembly having a plurality of cavity aligned, projecting plug assists. A plate incorporated with the mold assembly having the plug assists and operative to prevent ballooning of portions of the sheet surrounding those portions which are moved into the mold cavities by the plug assists has openings for passing the plug assists and is mounted for relative movement with the plug assists. The plate is moved toward the mold assembly having the mold cavities and engages the mold assembly having the mold cavities to clamp the edges of the plastic sheet thereto, prior to the time the plug assists are moved into the cavities to stretch the sheet and mechanically move portions of the sheet into the mold cavities. Thereafter a differential pressure condition is created to move the sheet portions finally into intimate engagement with the mold cavities.
Inventors
- 👤 Melvin Otto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:13
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/04; B29C2791/00; B29C2791/004; B29C2791/007; B29C51/08; B29C51/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
218 words
In differential pressure forming apparatus for forming synthetic plastic parts in a plastic sheet: opposed mold assemblies, one mold assembly having a plurality of mold cavities and the other comprising a plug assist support from which a plurality of plug assists, aligned with said cavities, project; means for supporting a deformable sheet of plastic in which parts are to be formed between said mold assemblies; means for relatively moving said mold assemblies from separated to engaged positions to cause said plug assists to enter said cavities and move portions of the plastic sheet into said cavities, and from engaged to separated positions to relatively withdraw said plug assists; plate means mounted for movement independently of said plug assist support for preventing ballooning of portions of the sheet around said first mentioned portions, and having through openings aligned with said cavities for passing said plug assists; means for moving said plate means in a direction toward the said one mold assembly and pressing the sheet against the said one mold assembly so that it also acts as a clamp frame for the sheet at the time said plug assists engage the sheet of plastic; and means for applying a differential pressure to opposite sides of the sheet to move the sheet finally into intimate engagement with the mold cavities.
Claim 2
Dependent Claim
218 words
In differential pressure forming apparatus for forming synthetic plastic parts in a plastic sheet: opposed mold assemblies, one mold assembly having a plurality of mold cavities and the other comprising a plug assist support from which a plurality of plug assists, aligned with said cavities, project; means for supporting a deformable sheet of plastic in which parts are to be formed between said mold assemblies; means for relatively moving said mold assemblies from separated to engaged positions to cause said plug assists to enter said cavities and move portions of the plastic sheet into said cavities, and from engaged to separated positions to relatively withdraw said plug assists; plate means mounted for movement independently of said plug assist support for preventing ballooning of portions of the sheet around said first mentioned portions, and having through openings aligned with said cavities for passing said plug assists; means for moving said plate means in a direction toward the said one mold assembly and pressing the sheet against the said one mold assembly so that it also acts as a clamp frame for the sheet at the time said plug assists engage the sheet of plastic; and means for applying a differential pressure to opposite sides of the sheet to move the sheet finally into intimate engagement with the mold cavities.
Claim 3
Dependent Claim
48 words
The combination defined in claim 1 wherein said means for applying a differential pressure includes means for supplying air under pressure to said mold assembly having plug assists; and sheet engaging projection means is provided on said plate means to act as a seal for the air supplied.
Claim 4
Dependent Claim
23 words
The combination defined in claim 1 in which said plate means comprises a hollow member; and means is provided for circulating coolant therethrough.
Claim 5
Dependent Claim
90 words
The combination defined in claim 1 in which said means for relatively moving said mold assemblies includes means for moving said other mold assembly to and fro; and said means for causing said plate means to move includes a lost motion connection between said means for moving said other mold assembly and said plate means and means for biasing said plate means in a direction to urge it toward said one mold assembly upon further movement of the other mold assembly, when the plate means engages the one mold assembly.
Claim 6
Dependent Claim
77 words
The combination defined in claim 4 in which the means defined by the dependent claim comprises a fluid pressure operated cylinder for moving said other mold assembly to and fro, and biasing cylinder means connecting said mold assembly and plate means and having a fluid chamber with fluid which is compressed when said plate means engages said one mold assembly and said other mold assembly continues its movement to dispose said plug assists in said mold cavities.
Claim 7
Dependent Claim
46 words
The combination defined in claim 1 in which said plug support includes a plug plate from which said plug assists project; and perimetral seal means is mounted to seal the space between said plate means and plug plate when the two are moved substantially into engagement.
Claim 8
Dependent Claim
35 words
The combination defined in claim 6 in which said plug plate has a perimetral groove in its upper surface and said seal means comprises a seal ring disposed therein and projecting out of said groove.
Claim 9
Dependent Claim
30 words
The combination defined in claim 6 in which a dependent guide pin is provided on said plate means and is telescopically received in a casing provided on said plug plate.
Claim 10
Dependent Claim
39 words
The combination defined in claim 5 in which said plate means and said one mold assembly are flush when clamped together and bars connecting said biasing cylinder means and plate means are received in grooves in said plate means.
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) | 1974-08-23 | 1975-02-22 | 1975-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-23 | 1979-02-22 | 1979-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-23 | 1983-02-22 | 1983-08-24 | $7700.00 | Window Closed / Lapsed |