US3937778A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of vacuum-pressure injection moulding
Assignee: Shibaura Machine Co Ltd
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Filing: 1974-10-24
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Granted: 1976-02-10
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Expires: 1994-10-24
Abstract
Abstract In a method for injection moulding of the type wherein gas or vapor evolved from the resin being moulded is vent through a vent opening provided for a heated cylinder at an intermediate point thereof, the vent opening is maintained at a reduced pressure during metering and a small quantity of vaporizable liquid is admitted into the vent opening during injection for increasing the pressure therein.
Inventors
- 👤 Shoichi Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:57
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/46; B29C45/58; B29C45/63
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
110 words
In a method of injection moulding of the type utilizing an injection moulding machine including a heated cylinder having a vent opening at an intermediate point between the opposite ends thereof and a screw rotatably contained in the cylinder and wherein the screw is rotated during metering but stopped during injection, the improvement which comprises the steps of maintaining a reduced pressure in said vent opening during the rotation of said screw, and introducing into said vent opening a predetermined quantity of vaporizable liquid at the same time when the rotation of said screw is stopped thus causing said liquid to evaporate to increase the pressure in said vent opening.
Claim 2
Dependent Claim
110 words
In a method of injection moulding of the type utilizing an injection moulding machine including a heated cylinder having a vent opening at an intermediate point between the opposite ends thereof and a screw rotatably contained in the cylinder and wherein the screw is rotated during metering but stopped during injection, the improvement which comprises the steps of maintaining a reduced pressure in said vent opening during the rotation of said screw, and introducing into said vent opening a predetermined quantity of vaporizable liquid at the same time when the rotation of said screw is stopped thus causing said liquid to evaporate to increase the pressure in said vent opening.
Claim 3
Dependent Claim
22 words
The method according to claim 1 wherein said vaporizable liquid is supplied into said vent opening as a fine stream or spray.
References Cited (Backward Citations)
US2207426A
Cited
FR1357270A
Cited
US3177272A
Cited
US3253303A
Cited
FR1338703A
Cited
US3488412A
Cited
US3485905A
Cited
US3577360A
Cited
US3822331A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-02-09 | 1979-08-11 | 1980-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-09 | 1983-08-11 | 1984-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-09 | 1987-08-11 | 1988-02-10 | $7700.00 | Window Closed / Lapsed |