US4942006A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of and apparatus for injection molding with pressurized-fluid assist
Assignee: Melea Ltd
•
Filing: 1988-12-01
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Granted: 1990-07-17
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Expires: 2008-12-01
Abstract
Abstract An injection molding method and nozzle for use therein wherein first and second variable pressures are applied to a piston of a valve mechanism of the nozzle so that a differential fluid pressure on the piston causes a tip portion of the valve mechanism to alternately open and close. In this way, the tip portion communicates the flow of resin from a nozzle body of the nozzle to an injection aperture of a mold. Differential pressure on the piston prevents a fluid which distributes the molten resin over the interior surfaces of the mold from entering the flow path of the molten resin in the nozzle body. The fluid preferably is a gas, such as nitrogen. Preferably, the piston is mounted for reciprocating movement within the nozzle body and the first pressure is provided by the resin during resin injection and the second pressure is partially applied by the nitrogen gas. Preferably, the valve mechanism includes a counterbalance mechanism which is set to prevent fluid entry into the mold until the tip portion of the valve mechanism is closed. The resulting article is then cooled to a temperature below the softening point of the resin, the pressure is relieved within the article and the mold is opened to remove the article. The nozzle may also be utilized in making structural foam articles from a foamable resin. The pressure within the mold is relieved to permit foaming by the foamable resin after injection of the foamable resin.
Inventors
- 👤 Norman S. Loren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:47
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/26; B29C45/27; B29C45/28; B29C45/2806; B29C44/00; B29C44/02; B29C44/10; B29C44/105; B29C45/1703; B29C45/1734; B29C45/1735; Y; Y10; Y10S; Y10S425/00; Y10S425/812
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
307 words
A method for making an article from at least one plastic resin having a softening point in an injection molding system including a pressurized fluid source, a mold having an injection aperture and interior surfaces, an injection nozzle having a nozzle body for establishing a flow path or molten resin through the injection aperture and valve means including a piston and a tip portion operatively associated with the piston to move therewith, the tip portion having a closed position and an open position to communicate the flow of plastic resin from the nozzle body through the injection aperture, the method including the steps of: (a) injecting an amount of molten resin for the article by applying a first variable pressure to the piston to cause the tip portion to move to its open position to communicate the flow of plastic resin from the injection nozzle through the injection aperture in the mold; (b) communicating pressurized fluid from the fluid source to the mold, to distribute the molten resin over the interior surfaces of the mold whereby a hollow body portion is formed; (c) applying a second variable pressure to the piston to urge the tip portion towards its closed position, a difference in the pressure between the first and second pressures causing the tip portion to move to its closed position, wherein the difference in pressure on the valve means prevents the fluid from entering the flow path of the molten resin in the nozzle body; (d) cooling the article to a temperature beneath the softening point of the resin; (e) relieving the pressure within the hollow body portion; and (f) opening the mold to remove the article wherein the improvement comprises: pressurized fluid from the fluid source applies at least a portion of the second variable pressure to urge the tip portion towards its closed position.
Claim 2
Independent Claim
307 words
A method for making an article from at least one plastic resin having a softening point in an injection molding system including a pressurized fluid source, a mold having an injection aperture and interior surfaces, an injection nozzle having a nozzle body for establishing a flow path or molten resin through the injection aperture and valve means including a piston and a tip portion operatively associated with the piston to move therewith, the tip portion having a closed position and an open position to communicate the flow of plastic resin from the nozzle body through the injection aperture, the method including the steps of: (a) injecting an amount of molten resin for the article by applying a first variable pressure to the piston to cause the tip portion to move to its open position to communicate the flow of plastic resin from the injection nozzle through the injection aperture in the mold; (b) communicating pressurized fluid from the fluid source to the mold, to distribute the molten resin over the interior surfaces of the mold whereby a hollow body portion is formed; (c) applying a second variable pressure to the piston to urge the tip portion towards its closed position, a difference in the pressure between the first and second pressures causing the tip portion to move to its closed position, wherein the difference in pressure on the valve means prevents the fluid from entering the flow path of the molten resin in the nozzle body; (d) cooling the article to a temperature beneath the softening point of the resin; (e) relieving the pressure within the hollow body portion; and (f) opening the mold to remove the article wherein the improvement comprises: pressurized fluid from the fluid source applies at least a portion of the second variable pressure to urge the tip portion towards its closed position.
Claim 3
Dependent Claim
23 words
The method as claimed in claim 1 further comprising the step of injecting an amount of molten resin into the hollow body portion.
Claim 4
Dependent Claim
32 words
The method as claimed in claim 1 wherein the piston is mounted for reciprocating movement within the nozzle body, the first pressure being provided by the resin during the resin injection step.
Claim 5
Dependent Claim
19 words
The method as claimed in claim 1 wherein the piston is mounted for reciprocating movement outside the nozzle body.
Claim 6
Dependent Claim
16 words
The method as claimed in claim 1 wherein the fluid is communicated through the injection aperture.
Claim 7
Dependent Claim
16 words
The method as claimed in claim 5 wherein the fluid is communicated through the tip portion.
Claim 8
Dependent Claim
21 words
The method as claimed in claim 1 wherein the pressure within the hollow body portion is relieved through the injection aperture.
Claim 9
Dependent Claim
24 words
The method as claimed in claim 7 wherein the pressure within the hollow body portion is at least partially relieved through the tip portion.
Claim 10
Dependent Claim
34 words
The method as claimed in claim 7 or claim 8 wherein the step of relieving the pressure is at least partially accomplished by separating the nozzle and the mold after the step of cooling.
Claim 11
Dependent Claim
13 words
The method as claimed in claim 1 wherein the fluid is a gas.
Claim 12
Dependent Claim
12 words
The method as claimed in claim 10 wherein the gas is nitrogen.
Claim 13
Dependent Claim
27 words
The method as claimed in claim 1 wherein the valve means includes a biasing means, the biasing means applying at least a portion of the second pressure.
Claim 14
Dependent Claim
22 words
The method as claimed in claim 1 wherein the fluid applies substantially all of the second pressure during said step of communicating.
Claim 15
Dependent Claim
49 words
The method as claimed in claim 1 wherein the hollow body portion is formed within the mold with a fluid entry opening therein, and wherein the method further comprises the step of injecting an amount of resin sufficient to close the fluid entry opening in the hollow body portion.
Claim 16
Dependent Claim
31 words
The method as claimed in claim 14 wherein the step of relieving is accomplished by opening the interior of the hollow body portion to ambient atmosphere after the step of cooling.
Claim 17
Dependent Claim
46 words
The method as in claim 1 or claim 14 wherein the mold defines therein a mold cavity of fixed volume having a form of the article to be formed therein and wherein the molten resin injected into the mold initially only partially fills the mold cavity.
Claim 18
Dependent Claim
53 words
The method as in claim 1 or claim 14 wherein said mold includes a female mold portion and a male mold portion movable within the female mold portion to define therein a mold cavity of variable volume and wherein the molten resin injected into the mold at least partially fills the mold cavity.
Claim 19
Dependent Claim
17 words
The method as in claim 17 wherein the volume is increased on injection thereinto of the fluid.
Claim 20
Dependent Claim
20 words
The method as claimed in claim 1 wherein the pressurized fluid is communicated to the mold downstream from the nozzle.
Claim 21
Dependent Claim
26 words
The method as claimed in claim 1 or claim 19 wherein the pressure within the hollowbody portion is at least partially relieved downstream from the nozzle.
Claim 22
Dependent Claim
222 words
A nozzle for use in a fluidassisted injection molding system including a pressurized fluid source, a mold having an injection aperture and an injection molding machine, the nozzle including a nozzle body having means for establishing a flow path for molten resin, a first end of the nozzle body being adapted for resin connection with the mold and a second end thereof being adapted for resin connection with an end of the injection molding machine; valve means for controlling the flow of resin through the nozzle body, the valve means including a piston and a tip portion operatively associated with the piston to move therewith, the valve means being adapted for reciprocating movement between an open position and a closed position, the tip portion communicating the flow of resin through the nozzle body in he open position, said piston having first and second surfaces, the tip portion moving between the open and closed positions by a pressure difference on the valve means to prevent the fluid from entering the flow path of the molten resin in the nozzle body and wherein the improvement comprises: the second surface of the piston is adapted to be in communication with pressurized fluid from the fluid source to urge the tip portion towards its closed position and to maintain the tip portion in the closed position.
Claim 23
Dependent Claim
222 words
A nozzle for use in a fluidassisted injection molding system including a pressurized fluid source, a mold having an injection aperture and an injection molding machine, the nozzle including a nozzle body having means for establishing a flow path for molten resin, a first end of the nozzle body being adapted for resin connection with the mold and a second end thereof being adapted for resin connection with an end of the injection molding machine; valve means for controlling the flow of resin through the nozzle body, the valve means including a piston and a tip portion operatively associated with the piston to move therewith, the valve means being adapted for reciprocating movement between an open position and a closed position, the tip portion communicating the flow of resin through the nozzle body in he open position, said piston having first and second surfaces, the tip portion moving between the open and closed positions by a pressure difference on the valve means to prevent the fluid from entering the flow path of the molten resin in the nozzle body and wherein the improvement comprises: the second surface of the piston is adapted to be in communication with pressurized fluid from the fluid source to urge the tip portion towards its closed position and to maintain the tip portion in the closed position.
Claim 24
Dependent Claim
30 words
The nozzle as claimed in claim 21 wherein the valve means is housed within the nozzle body and the first surface of the piston is in communication with the resin.
Claim 25
Dependent Claim
36 words
The nozzle as claimed in claim 21 wherein the piston is mounted for reciprocating movement outside of the nozzle body and wherein fluid from the fluid source applies pressure to the first surface of the piston.
Claim 26
Dependent Claim
49 words
The nozzle as claimed in claim 21 or claim 22 or claim 23 wherein the valve means has a fluid passage formed therein and open at one end thereof through the tip portion, the fluid passage and the tip portion communicating the flow of pressurized fluid into the mold.
Claim 27
Dependent Claim
16 words
The nozzle as claimed in claim 22 or claim 23 wherein the fluid is a gas.
Claim 28
Dependent Claim
12 words
The nozzle as claimed in claim 25 wherein the gas is nitrogen.
Claim 29
Dependent Claim
22 words
The nozzle as claimed in claim 22 or claim 23 wherein said valve means further includes biasing means for biasing the piston.
Claim 30
Dependent Claim
27 words
The nozzle as claimed in claim 27 wherein the biasing means includes a spring operatively associated with the second surface of the piston to bias the piston.
Claim 31
Dependent Claim
25 words
The nozzle as claimed in claim 24 further comprising a check valve disposed in the fluid passage for regulating the flow of pressurized fluid therethrough.
Claim 32
Dependent Claim
24 words
The nozzle as claimed in claim 22 or claim 23 wherein the nozzle is adapted for use in a multi-nozzle hot runner manifold system.
Claim 33
Dependent Claim
33 words
The nozzle as claimed in claim 22 or claim 23 wherein said tip portion is operatively associated with the first end of the nozzle body to define a resin orifice of the nozzle.
Claim 34
Dependent Claim
29 words
The nozzle as claimed in claim 31 wherein the nozzle body includes an interchangeable first end and a common tip portion to vary the size of the resin orifice.
Claim 35
Dependent Claim
36 words
The nozzle as claimed in claim 22 or claim 23 further comprising sealing means disposed within the nozzle body or preventing the communication of the fluid and the resin within the nozzle body at the piston.
Claim 36
Dependent Claim
38 words
The nozzle as claimed in claim 21 or claim 22 or claim 23 wherein said valve means includes a counterbalance mechanism to prevent fluid entry into the mold until the tip portion of the valve means is closed.
Claim 37
Dependent Claim
36 words
The nozzle as claimed in claim 34 wherein said counterbalance mechanism includes spring means for applying a spring force, the spring force being larger than that required to move the tip portion to its closed position.
Claim 38
Independent Claim
217 words
A method for making a structural foam article from a foamable resin having a softening point in an injection molding system including a pressurized fluid source, a mold having interior surfaces and an injection nozzle having a nozzle body for establishing a flow path for molten resin and a valve means having a piston and a tip portion operatively associated with the piston to move therewith, the method comprising the steps of: (a) pressurizing the mold to a predetermined pressure; (b) injecting an amount of foamable resin sufficient for at least partial preparation of the article from the injection nozzle through an injection aperture in the mold, the resin being in communication with a first surface of the piston to cause the tip portion to move towards its open position; (c) causing the piston to move by differential pressure at the valve means to thereby move the tip portion to its closed position; (d) relieving the pressure within the mold to permit foaming by the resin; (e) cooling the article to a temperature beneath the softening point of the resin; and (f) opening the mold to remove the article wherein the improvement comprises: pressurized fluid from the fluid source applies at least a portion of the differential pressure to urge the tip portion towards its closed position.
Claim 39
Independent Claim
217 words
A method for making a structural foam article from a foamable resin having a softening point in an injection molding system including a pressurized fluid source, a mold having interior surfaces and an injection nozzle having a nozzle body for establishing a flow path for molten resin and a valve means having a piston and a tip portion operatively associated with the piston to move therewith, the method comprising the steps of: (a) pressurizing the mold to a predetermined pressure; (b) injecting an amount of foamable resin sufficient for at least partial preparation of the article from the injection nozzle through an injection aperture in the mold, the resin being in communication with a first surface of the piston to cause the tip portion to move towards its open position; (c) causing the piston to move by differential pressure at the valve means to thereby move the tip portion to its closed position; (d) relieving the pressure within the mold to permit foaming by the resin; (e) cooling the article to a temperature beneath the softening point of the resin; and (f) opening the mold to remove the article wherein the improvement comprises: pressurized fluid from the fluid source applies at least a portion of the differential pressure to urge the tip portion towards its closed position.
Claim 40
Dependent Claim
32 words
The method as claimed in claim 36 further comprising the step of injecting a fluid into the mold under pressure to distribute the molten resin over the interior surfaces of the mold.
Claim 41
Dependent Claim
26 words
The method as claimed in claim 37 further comprising the step of further relieving the pressure within the article after the step of injecting the fluid.
Claim 42
Dependent Claim
37 words
The method as claimed in claim 38 wherein the valve means has a fluid passage formed therein and wherein the step of further relieving is accomplished by venting the pressure within the mold through the fluid passage.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-16 | 1994-01-15 | 1994-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-16 | 1998-01-15 | 1998-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-16 | 2002-01-15 | 2002-07-17 | $7700.00 | Window Closed / Lapsed |