Patent US3728053A successfully refreshed from Google Patents.
US3728053A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for the injection molding of plastic objects
Assignee: Individual
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Filing: 1970-08-26
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Granted: 1973-04-17
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Expires: 1990-08-26
Abstract
Abstract In the formation of plastic objects having an imporous dense film-like surface enclosing a foam-like porous core, the plastic material and an expanding agent are mixed, heated to a hot plastic compound, and transported through an enclosed axially elongated passageway by a threaded screw member. The threaded screw member is shaped to provide a flow path of variable transverse cross sectional area along its length. By axially displacing the screw member, dosed amounts of hot plastic compound, collected at the outlet end of the passageway, can be extruded for injection into a mold.
Inventors
- 👤 B Stillhard
- 👤 F Scheifele
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:07
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/3442; B29C44/3446; B29C44/3449; B29C44/02; B29C44/04; B29C44/0492; B29C45/00; B29C45/17; B29C45/46; B29C45/47; B29C45/50; Y; Y10; Y10S; Y10S264/00; Y10S264/83
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
369 words
Apparatus for intermittent fabrication of objects of limited volume, having an imporous dense film surface enclosing a foamlike porous core, by injection molding of plastic material being accumulated in a chamber and intermittently forced through a nozzle into a cavity, having a limited and wholly enclosed filling volume, of a split mold which can be opened in cadence with the intermittent fabrication of the objects, said apparatus comprising in combination, an elongated plasticization and injection cylinder extending from a material inlet to a material injection outlet communicating with said nozzle; and a plasticization and injection screw mounted in said cylinder for rotation and axial displacement therein and extending therethrough; said cylinder including a first elongated section, of substantially uniform diameter, extending from said material inlet, and a second section extending from said first section to said material injection outlet, and including an intermediate portion having a substantially uniform diameter larger than that of said first section, a frusto-conical transition portion diverging from said first section to said intermediate portion, and a further portion extending from said intermediate portion to said outlet; said further portion and at least a part of said intermediate portion constituting said chamber; said screw having a first threaded section with an outer diameter substantially equal to the inner diameter of said first cylinder section and extending through said first cylinder section, and a second section in said second cylinder section including an intermediate portion having an outer diameter substantially equal to the inner diameter of said second cylinder section intermediate portion, a transition-threaded section having an outer surface conforming to the inner surface of said transition portion of said cylinder second section, and further portion extending from said screw intermediate portion into said further portion of said second cylinder section; the axial length of said screw intermediate portion being less than the axial length of the intermediate portion of said second cylinder section; said screw being axially displaceable rearwardly in said cylinder, to obtain plasticization of the material, during accumulation of the material in said chamber and, after completion of plasticization of the material, being axially displaceable forwardly in said cylinder, to inject plasticized material, accumulated in said chamber, into said limited volume mold cavity.
Claim 2
Dependent Claim
369 words
Apparatus for intermittent fabrication of objects of limited volume, having an imporous dense film surface enclosing a foamlike porous core, by injection molding of plastic material being accumulated in a chamber and intermittently forced through a nozzle into a cavity, having a limited and wholly enclosed filling volume, of a split mold which can be opened in cadence with the intermittent fabrication of the objects, said apparatus comprising in combination, an elongated plasticization and injection cylinder extending from a material inlet to a material injection outlet communicating with said nozzle; and a plasticization and injection screw mounted in said cylinder for rotation and axial displacement therein and extending therethrough; said cylinder including a first elongated section, of substantially uniform diameter, extending from said material inlet, and a second section extending from said first section to said material injection outlet, and including an intermediate portion having a substantially uniform diameter larger than that of said first section, a frusto-conical transition portion diverging from said first section to said intermediate portion, and a further portion extending from said intermediate portion to said outlet; said further portion and at least a part of said intermediate portion constituting said chamber; said screw having a first threaded section with an outer diameter substantially equal to the inner diameter of said first cylinder section and extending through said first cylinder section, and a second section in said second cylinder section including an intermediate portion having an outer diameter substantially equal to the inner diameter of said second cylinder section intermediate portion, a transition-threaded section having an outer surface conforming to the inner surface of said transition portion of said cylinder second section, and further portion extending from said screw intermediate portion into said further portion of said second cylinder section; the axial length of said screw intermediate portion being less than the axial length of the intermediate portion of said second cylinder section; said screw being axially displaceable rearwardly in said cylinder, to obtain plasticization of the material, during accumulation of the material in said chamber and, after completion of plasticization of the material, being axially displaceable forwardly in said cylinder, to inject plasticized material, accumulated in said chamber, into said limited volume mold cavity.
Claim 3
Dependent Claim
82 words
Apparatus for injection molding plastic objects, as set forth in claim 1, wherein said screw intermediate portion has an annular groove therein; and an annular return flow block member positioned in said groove for limited axial displacement relative thereto; said return flow block member preventing return flow of the plastic material in the direction of the threaded portion of said screw when the material is being extruded from the outlet of said cylinder by axial displacement of said screw toward said outlet.
Claim 4
Dependent Claim
49 words
Apparatus for injection molding of plastic objects, as set forth in claim 1, wherein the threaded portion of said screw located within the frusto-conical portion of said second cylinder section has threads thereon for the extent of the axial dimension of the frusto-conical portion of said second cylinder section.
Claim 5
Dependent Claim
69 words
Apparatus for injection molding of plastic objects, as set forth in claim 2, wherein said return flow block member is spaced, in the direction of the outlet opening, from the end of the threaded portion of said screw within the frusto-conical portion of said second cylinder section, and said block member has an outside diameter corresponding to the inside diameter of said intermediate portion of said second cylinder section.
Claim 6
Dependent Claim
28 words
Apparatus for injection molding of plastic objects, as set forth in claim 1, wherein said second screw section is removable from and replaceable on said first screw section.
Claim 7
Dependent Claim
64 words
Apparatus for injection molding plastic objects, as set forth in claim 1, including a displacement member secured to said screw at its end adjacent said material inlet for axially displacing said screw both toward and away from said material injection outlet; and means operable to move said displacement member axially through selected axial distances in accordance with the parameters of the injection molding operation.
Claim 8
Dependent Claim
52 words
Apparatus for injection molding of plastic objects, as set forth in claim 6, wherein means are arranged for rotating said screw about its longitudinal axis and said displacement member is operative during the operation of said rotating means to inhibit axial displacement of said screw away from said material injection outlet way.
Claim 9
Dependent Claim
39 words
Apparatus for injection molding of plastic objects, as set forth in claim 1, wherein said first cylinder section has a first inlet opening spaced longitudinally from said second cylinder section for charging at least plastic material into said cylinder.
Claim 10
Dependent Claim
41 words
Apparatus for injection molding of plastic objects, as set forth in claim 8, wherein said first cylinder section has a second inlet opening spaced longitudinally from said first inlet opening toward said outlet for charging the expanding agent into said cylinder.
Claim 11
Dependent Claim
36 words
Apparatus for injection molding of plastic objects, as set forth in claim 9, wherein the second inlet opening within said firsT cylinder section is positioned adjacent to the junction of said first and second cylinder sections.
Claim 12
Dependent Claim
79 words
Apparatus for injection molding of plastic objects, as set forth in claim 1, wherein said screw member comprises a core and a continuous thread projecting outwardly from said core, said core having a variable diameter for at least a portion of its length increasing in the direction of the outlet, whereby the spaces defined between said core and the opposed surfaces of said thread and the inside surface of said cylinder vary along the axial direction of said screw.
Claim 13
Dependent Claim
45 words
Apparatus for injection molding plastic objects, as set forth in claim 1, wherein said further portion of said screw is frusto-conical and tapers toward said material injection outlet; said further portion of said second cylinder section being frusto-conical and converging toward said material injection outlet.
Claim 14
Dependent Claim
45 words
Apparatus for injection molding of plastic objects, as set forth in claim 1, wherein at least one heater sleeve is located on each of said first cylinder section and second cylinder section for supplying heat to the materials con-veyed through said cylinder by said screw.
Claim 15
Dependent Claim
51 words
Apparatus for injection molding plastic objects, as set forth in claim 1, wherein the axial length of said screw intermediate portion is less than the axial length of the intermediate portion of said second cylinder section by an amount equal to the maximum axial displacement of said screw in said cylinder.
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) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |