US3655313A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plastic injection molding apparatus
Assignee: MEIKI SEISGKUSHO Ltd
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Filing: 1970-06-03
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Granted: 1972-04-11
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Expires: 1990-06-03
Abstract
Abstract An injection molding apparatus is provided characterized by having an injection screw rod rotatably and reciprocably mounted in a heating cylinder, there being a channel between the thread convolutions on the screw rod, and a portion of that channel correspondingly in the metering zone of the screw rod being shallow in depth within limits prescribed by empirical formula so as to have the screw rod efficiently constrain against backflow of molten plastic material on injection stroke, and there further being drive means and feed means interrelated in the apparatus for the feed means to supply raw plastic material to the screw rod in a feed zone of the latter at a rate commensurate with power demanded of the drive means for rotating the screw rod to feed raw plastic material forwardly from the feed zone being within practical limits.
Inventors
- 👤 Mahito Kunogi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:32
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/46; B29C45/47; B29C45/50; B29C45/18; B29C45/1866; B29C2045/1875
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
335 words
In an injection molding apparatus for plastics, the combination comprising, an injection screw rod rotatably and reciprocably mounted in a heating cylinder and provided with a screw thread and a convoluted channel intermediate said thread for feeding plastic material through said cylinder in a generally forward direction on forward-feed rotation of said screw rod, portions of said thread and channel extending on a forward portion of said screw rod to define a metering zone on forwardfeed rotation of said screw rod with depth of said channel in said channel portion being within the range represented in millimeters by h in the empirical formula: h 0.2 square root 3 LD Eta D being the outside diameter of said screw thread portion, L being the length of said forward portion of said screw rod, both L and D being in millimeters, and Eta being a value in the range of about 0.01 to 0.1, for said forward portion of said screw rod to arrest backflow of plastic material in said cylinder during an injection stroke of said screw rod, and said screw thread and channel leading backwardly on said screw rod along intermediate and rearward portions of said screw rod from said screw rod forward portion for said screw thread and channel intermediately to be in a compression zone and rearwardly in a feed zone on forward-feed rotation of said screw rod, drive means for rotating said screw rod at a speed and in a direction for feeding raw plastic material forwardly from said feed zone in quantities to be plasticized commensurate with achieving a useful rate of metering of plasticized material from said metering zone, and feed means for supplying raw plastic material to said screw thread in said feed zone at a rate commensurate with power demand on said drive means being within practical limits while said screw rod is driven at said speed of rotation on operation of said drive means and is issuing plasticized material from said metering zone at said metering rate.
Claim 2
Dependent Claim
335 words
In an injection molding apparatus for plastics, the combination comprising, an injection screw rod rotatably and reciprocably mounted in a heating cylinder and provided with a screw thread and a convoluted channel intermediate said thread for feeding plastic material through said cylinder in a generally forward direction on forward-feed rotation of said screw rod, portions of said thread and channel extending on a forward portion of said screw rod to define a metering zone on forwardfeed rotation of said screw rod with depth of said channel in said channel portion being within the range represented in millimeters by h in the empirical formula: h 0.2 square root 3 LD Eta D being the outside diameter of said screw thread portion, L being the length of said forward portion of said screw rod, both L and D being in millimeters, and Eta being a value in the range of about 0.01 to 0.1, for said forward portion of said screw rod to arrest backflow of plastic material in said cylinder during an injection stroke of said screw rod, and said screw thread and channel leading backwardly on said screw rod along intermediate and rearward portions of said screw rod from said screw rod forward portion for said screw thread and channel intermediately to be in a compression zone and rearwardly in a feed zone on forward-feed rotation of said screw rod, drive means for rotating said screw rod at a speed and in a direction for feeding raw plastic material forwardly from said feed zone in quantities to be plasticized commensurate with achieving a useful rate of metering of plasticized material from said metering zone, and feed means for supplying raw plastic material to said screw thread in said feed zone at a rate commensurate with power demand on said drive means being within practical limits while said screw rod is driven at said speed of rotation on operation of said drive means and is issuing plasticized material from said metering zone at said metering rate.
Claim 3
Dependent Claim
62 words
An injection molding apparatus for plastics as set forth in claim 1 wherein said feed means includes feed screw means communicating with said feed zone and driven for metering raw plastic material to said thread of said screw rod while said screw rod is rotating in response to said drive means and is feeding raw plastic material forwardly from said feed zone.
Claim 4
Dependent Claim
89 words
An injection molding apparatus for plastics as set forth in claim 2 wherein said feed screw means includes a feed screw having a first thread portion disposed beneath supply hopper means so as to receive and feed raw plastic material from said hopper means into an opening communicating in said heating cylinder with said feed zone, and said feed screw having a second thread portion communicating with said opening, and the lead direction of said second thread portion being opposite to the lead direction of saiD first thread portion.
Claim 5
Dependent Claim
43 words
An injection molding apparatus for plastics as set forth in claim 1 wherein cooling means is provided for reducing temperatures of said forward portion of said screw rod which tend to rise during forward-feed rotation of said screw rod in said heating cylinder.
Claim 6
Dependent Claim
61 words
An injection molding apparatus for plastics as set forth in claim 2 wherein hopper means is provided having a plurality of supply compartments communicating with said feed screw means and thence with said feed zone for said feed screw means to receive and feed a plurality of different kinds of raw plastic material from said compartments to said screw rod thread.
Claim 7
Dependent Claim
47 words
An injection molding apparatus for plastics as set forth in claim 2 wherein a variable speed transmission is interposed between said screw rod and said feed screw means for the ratio between the feed rates of said screw rod and said feed screw means to be varied.
Claim 8
Dependent Claim
114 words
An injection molding apparatus for plastics as set forth in claim 5 wherein said feed screw means includes a rotatably mounted first screw portion disposed beneath one of said plurality of supply compartments and operatively connected for rotating with said screw rod, and a second screw portion relatively rotatably mounted with reference to said first screw portion and disposed beneath another of said plurality of supply compartments, said second screw portion being operatively connected through a variable speed transmission with said screw rod for rotating with said screw rod and for speed of rotation of said second screw portion to be varied with reference to said speed of rotation of said first screw portion.
Claim 9
Dependent Claim
60 words
An injection molding apparatus for plastics as set forth in claim 1 wherein said rate of feed of said feed means and said speed of rotation of said screw rod are interrelated for said screw rod rotating in response to said drive means and on feed of said feed means to have in effect a compression ratio less than maximum.
Claim 10
Dependent Claim
61 words
An injection molding apparatus for plastics as set forth in claim 1 wherein said rate of feed of said feed means and said speed of rotation of said screw rod are variably interrelated for controlling said screw rod rotating in response to said drive means and on feed of said feed means to have in effect a selectively different compression ratio.
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) | 1975-04-11 | 1975-10-11 | 1976-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-11 | 1979-10-11 | 1980-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-11 | 1983-10-11 | 1984-04-11 | $7700.00 | Window Closed / Lapsed |