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US5059370A
Expired / Lapsed
US
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Injection molding method using surge pressure
Assignee: SMT Inc
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Filing: 1989-06-20
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Granted: 1991-10-22
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Expires: 2009-06-20
Abstract
Abstract A surge of high pressure is momentarily applied to a plasticized molding material injected in a mold cavity immediately after the completion of an injection process so that molding shrinkage and orientation which are caused in the material in the mold cavity in the course of solidification of the material on cooling can be substantially eliminated to thereby enable super-precision injection molding.
Inventors
- 👤 Hisashi Kojima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:39
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/26; B29C45/34; B29C45/263; B29C45/46; B29C45/56; B29C45/561; B29C45/57; B29L; B29L2011/00; B29L2011/0016
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
102 words
An injection molding method comprising evacuating a mold cavity in an injection mold to a high vacuum of 10 -1 Torr to 10 -7 Torr, injecting a plasticized molding material into said mold cavity, momentarily applying a surge pressure of 1.2 to 1.5 times an injection pressure at which the molding material is injected into said mold cavity to the molding material injected in said mold cavity simultaneously with or within 0.01 to 0.05 second immediately after the completion of the injection of the molding material into said mold cavity, and effecting gate cutting immediately after the application of the surge pressure.
Claim 2
Dependent Claim
102 words
An injection molding method comprising evacuating a mold cavity in an injection mold to a high vacuum of 10 -1 Torr to 10 -7 Torr, injecting a plasticized molding material into said mold cavity, momentarily applying a surge pressure of 1.2 to 1.5 times an injection pressure at which the molding material is injected into said mold cavity to the molding material injected in said mold cavity simultaneously with or within 0.01 to 0.05 second immediately after the completion of the injection of the molding material into said mold cavity, and effecting gate cutting immediately after the application of the surge pressure.
Claim 3
Dependent Claim
27 words
An injection molding method according to claim 1 wherein a compression pressure is applied to the molding material in said mold cavity immediately after the gate cutting.
Claim 4
Dependent Claim
34 words
An injection molding method according to claim 1 wherein a compression pressure is applied to the molding material in said mold cavity immediately after the gate cutting and thereafter maintained in a dwelling process.
Claim 5
Dependent Claim
19 words
An injection molding method according to claim 1, wherein the surge pressure is applied for 0.01 to 0.10 second.
Claim 6
Dependent Claim
143 words
An injection molding method comprising evacuating a mold cavity inside an injection mold to a high vacuum of 10 -1 Torr to 10 -7 Torr, injecting a plasticized molding material into said mold cavity in accordance with a predetermined internal die pressure given in a waveform pattern, momentarily applying a surge pressure of 1.2 to 1.5 times an injection pressure at which the molding material is injected into said mold cavity to the molding material injected in said mold cavity simultaneously with or within 0.01 to 0.05 second immediately after the completion of the injection of the molding material into said mold cavity so as to prevent the molding material in said mold cavity from solidifying except for a skin layer in touch with an inner surface of said mold cavity, and effecting gate cutting immediately after the application of the surge pressure.
Claim 7
Dependent Claim
143 words
An injection molding method comprising evacuating a mold cavity inside an injection mold to a high vacuum of 10 -1 Torr to 10 -7 Torr, injecting a plasticized molding material into said mold cavity in accordance with a predetermined internal die pressure given in a waveform pattern, momentarily applying a surge pressure of 1.2 to 1.5 times an injection pressure at which the molding material is injected into said mold cavity to the molding material injected in said mold cavity simultaneously with or within 0.01 to 0.05 second immediately after the completion of the injection of the molding material into said mold cavity so as to prevent the molding material in said mold cavity from solidifying except for a skin layer in touch with an inner surface of said mold cavity, and effecting gate cutting immediately after the application of the surge pressure.
Claim 8
Dependent Claim
19 words
An injection molding method according to claim 5, wherein the surge pressure is applied for 0.01 to 0.10 second.
References Cited (Backward Citations)
US3989436A
Cited
US4879082A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-10-21 | 1995-04-22 | 1995-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-21 | 1999-04-22 | 1999-10-22 | $3760.00 | Window Closed / Lapsed |
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