US3642402A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Injection molding process control
Assignee: Pennwalt Corp
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Filing: 1970-03-10
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Granted: 1972-02-15
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Expires: 1990-03-10
Abstract
Abstract Process control for an injection molding machine measures the viscosity characteristics of the plasticized material by monitoring pressure in the melt stream being injected at a predetermined position of the forward stroke of the ram during flow of the material into the mold. If the pressure-viscosity exceeds or falls below the previously determined band limits set, the heat input to subsequent shots being prepared is respectively raised or lowered by (1) increasing or decreasing barrel temperature, (2) increasing or decreasing speed of screw rotation, or (3) increasing or decreasing back pressure on the screw during rotation thereof.
Inventors
- 👤 Herman R Hutchinson
- 👤 Vasken F Arpajian
- 👤 Robert S Malcomson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:44
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/76; B29C45/7646
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
144 words
Automatic control apparatus for a molding machine having a ram for injecting hot plasticized material into a mold comprising: means for heating the plasticized material prior to injection into the mold, measuring means in the melt stream for monitoring the viscosity characteristics of the plasticized material in each shot being injected during the forward stroke of the ram at the time of flow of the material into the mold, and first actuating means responsive to said measuring means when the viscosity of the melt stream exceeds a predetermined level and operatively associated with said means for heating to increase the temperature of the melt stream in subsequent shots, and second actuating means responsive to said measuring means when the viscosity falls below a predetermined level and operatively associated with said means for heating to decrease the temperature of the melt stream in subsequent shots.
Claim 2
Dependent Claim
144 words
Automatic control apparatus for a molding machine having a ram for injecting hot plasticized material into a mold comprising: means for heating the plasticized material prior to injection into the mold, measuring means in the melt stream for monitoring the viscosity characteristics of the plasticized material in each shot being injected during the forward stroke of the ram at the time of flow of the material into the mold, and first actuating means responsive to said measuring means when the viscosity of the melt stream exceeds a predetermined level and operatively associated with said means for heating to increase the temperature of the melt stream in subsequent shots, and second actuating means responsive to said measuring means when the viscosity falls below a predetermined level and operatively associated with said means for heating to decrease the temperature of the melt stream in subsequent shots.
Claim 3
Dependent Claim
21 words
The invention of claim 1 wherein said means for monitoring comprises a transducer which measures pressure as a function of viscosity.
Claim 4
Dependent Claim
22 words
The invention of claim 1 wherein the respective increase and decrease in temperature of the melt stream is effected in predetermined increments.
Claim 5
Dependent Claim
36 words
The invention of claim 1 wherein the respective increase and decrease in temperature of the melt stream is effected by respectively raising and lowering the temperature of said means for heating during generation of subsequent shots.
Claim 6
Dependent Claim
41 words
The invention of claim 1 wherein said ram constitutes a rotatable screw, and the respective increase and decrease in temperature of the melt stream is effected by respectively increasing and decreasing the speed of screw rotation during generation of subsequent shots.
Claim 7
Dependent Claim
47 words
The invention of claim 1 wherein said ram is hydraulically operated and comprises a rotatable screw, and the respective increase and decrease in temperature of the melt stream is effected by respectively increasing and decreasing the hydraulic back pressure on said screw during generation of subsequent shots.
Claim 8
Dependent Claim
24 words
The invention of claim 2 wherein said molding machine is an injection-type apparatus having a nozzle and said transducer is located in the nozzle.
Claim 9
Dependent Claim
36 words
The invention of claim 1 including means to disarm each of said actuating means a predetermined number of injection shots after temperature correction has been made whereby the viscosity level may be allowed to reach equilibrium.
Claim 10
Dependent Claim
28 words
The invention of claim 8 wherein the first and second actuating means are adapted to be reactivated respectively after a predetermined number of injection shots have been made.
Claim 11
Dependent Claim
26 words
The invention of claim 8 wherein each of said actuating means is adapted to be activated for at least two temperature increments in the same direction.
Claim 12
Dependent Claim
26 words
The invention of claim 10 including an alarm which is energized after a predetermined number of successive temperature corrections have been made in the same direction.
Claim 13
Dependent Claim
136 words
Automatic control apparatus for a molding machine having a ram for injecting hot plasticized material into a mold comprising: means for heating the plasticized material prior to injection into the mold, measuring means for monitoring the viscosity characteristics of the plasticized material in the melt stream during a predetermined portion of the forward stroke of the ram at the time a shot is being injected and material flows into the mold, and first and second actuating means responsive to said measuring means and respectively activated when the viscosity exceeds and falls below a predetermined level, said first actuating means operating said means for heating to increase the temperature of the melt stream in subsequent shots and said second actuating means operating said means for heating to decrease the temperature of the melt stream in subsequent shots.
Claim 14
Dependent Claim
136 words
Automatic control apparatus for a molding machine having a ram for injecting hot plasticized material into a mold comprising: means for heating the plasticized material prior to injection into the mold, measuring means for monitoring the viscosity characteristics of the plasticized material in the melt stream during a predetermined portion of the forward stroke of the ram at the time a shot is being injected and material flows into the mold, and first and second actuating means responsive to said measuring means and respectively activated when the viscosity exceeds and falls below a predetermined level, said first actuating means operating said means for heating to increase the temperature of the melt stream in subsequent shots and said second actuating means operating said means for heating to decrease the temperature of the melt stream in subsequent shots.
Claim 15
Dependent Claim
17 words
The invention of claim 12 wherein said means for monitoring measures pressure as a function of viscosity.
Claim 16
Dependent Claim
22 words
The invention of claim 12 wherein the respective increase and decrease in temperature of the melt stream is effected in predetermined increments.
Claim 17
Dependent Claim
36 words
The invention of claim 12 wherein the respective increase and decrease in temperature of the melt stream is effected by respectively raising and lowering the temperature of said means for heating during generation of subsequent shots.
Claim 18
Dependent Claim
41 words
The invention of claim 12 wherein said ram constitutes a rotatable screw, and the respective increase and decrease in temperature of the melt stream is effected by respectively increasing and decreasing the speed of screw rotation during generation of subsequent shots.
Claim 19
Dependent Claim
47 words
The invention of claim 12 wherein said ram is hydraulically operated and comprises a rotatable screw, and the respective increase and decrease in temperature of the melt stream is effected by respectivelY increasing and decreasing the hydraulic back pressure on said screw during generation of subsequent shots.
Claim 20
Dependent Claim
136 words
Automatic control apparatus for an injection molding machine comprising: means for injecting plasticized material into a mold, means for heating the plasticized material prior to injection into the mold, measuring means in the melt stream for monitoring the viscosity characteristics of the plasticized material at the time a shot is being injected and material flows into the mold, and actuating means activated by said measuring means when the viscosity of the melt stream is outside a predetermined band, said actuating means operating said means for heating to increase the temperature of the melt stream in subsequent shots when the monitored viscosity is above the band range, and said actuating means operating upon said means for heating to decrease the temperature of the melt stream in subsequent shots when the monitored viscosity is below the band range.
Claim 21
Dependent Claim
136 words
Automatic control apparatus for an injection molding machine comprising: means for injecting plasticized material into a mold, means for heating the plasticized material prior to injection into the mold, measuring means in the melt stream for monitoring the viscosity characteristics of the plasticized material at the time a shot is being injected and material flows into the mold, and actuating means activated by said measuring means when the viscosity of the melt stream is outside a predetermined band, said actuating means operating said means for heating to increase the temperature of the melt stream in subsequent shots when the monitored viscosity is above the band range, and said actuating means operating upon said means for heating to decrease the temperature of the melt stream in subsequent shots when the monitored viscosity is below the band range.
Claim 22
Dependent Claim
32 words
The apparatus of claim 18 wherein said actuating means includes high-level set points triggered at the upper end of the band and low-level set points at the bottom end of the band.
Claim 23
Dependent Claim
41 words
The apparatus of claim 19 wherein said high-level set points control an electronic circuit for raising the temperature of said means for heating and said low-level set points control an electronic circuit for lowering the temperature of said means for heating.
Claim 24
Dependent Claim
30 words
The apparatus of claim 18 wherein said means for injecting comprises a reciprocable ram, said measuring means being tripped at a predetermined position of the ram during the advancement thereof.
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) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |