US3860801A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Injection molding control
Assignee: Individual
•
Filing: 1973-06-19
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Granted: 1975-01-14
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Expires: 1993-06-19
Abstract
Abstract An injection molding control to promote uniformity in the mass of the injection charge from cycle to cycle. An injection ram is reciprocated between a fixed forward, or cushion, point coincident with the end of charge injection, and an adjustable rearward, or retraction, point correlated to size of the next charge. The retraction point is corrected at the conclusion of each injection cycle in response to comparing a reference pressure, which is correlated to the mold cavity pressure existing at the conclusion of injecting a charge of the desired mass into the molding cavity, with the pressure of the plasticized material upstream of the orifice through which the material is injected into the mold cavity. The material pressure upstream of the orifice is sampled for comparison against the reference pressure at a point in time following injection when the ram has a predetermined velocity, preferably when it has come to rest, and the injected material in the region of the orifice has not yet solidified, whereby the sampled melt pressure is correlated to the cavity pressure at the conclusion of injection and hence to the mass of the injection charge. Depending upon whether the sampled melt pressure upstream of the orifice is above or below the reference pressure, the retraction point is shifted closer to, or further from, the orifice, respectively, to shorten or extend, respectively, the distance over which plasticized material for the next charge is accumulated forward of the ram tip.
Inventors
- 👤 Denes B Hunkar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:48
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/76
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
402 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, said ram being reciprocated between a variable retracted position and a fixed forward position, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive connected in force-transmitting relationship with said ram for advancing said ram toward said orifice from said retracted position to said fixed forward position to inject plasticized material from said barrel into said cavity via said orifice, and from said forward position to said retracted position, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, a position sensor responsive to the position of said ram for providing a signal correlated to the position of said ram in said barrel, control means connected to said position sensor for generating a control signal when said ram reaches said forward position, said control signal being coupled to said ram drive means for terminating said ram advancing motion when said ram reaches said forward position, ram holding means connected in forcetransmitting relationship with said ram and responsive to said control signal for holding said ram in said forward position during at least a portion of the time plasticized material injected into said cavity solidifies, sample means responsive to said control signal for sampling the output signal of said pressure transducer to produce a sampled pressure signal when said ram advancement has substantially terminated at said fixed forward position and injected plastic material in said orifice has not yet solidified, whereby the sampled pressure signal is correlated to the pressure in said cavity and hence to the mass of injected material, reference signal means for providing a reference signal correlated to a predetermined barrel pressure, correction means including a comparator responsive to said sampled pressure signal and said reference signal for producing a retraction point correction signal, and means responsive to said retraction point correction signal for varying said retracted position from which said ram advances to inject plasticized material into said cavity to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure at the conclusion of injection of the preceding charge.
Claim 2
Dependent Claim
402 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, said ram being reciprocated between a variable retracted position and a fixed forward position, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive connected in force-transmitting relationship with said ram for advancing said ram toward said orifice from said retracted position to said fixed forward position to inject plasticized material from said barrel into said cavity via said orifice, and from said forward position to said retracted position, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, a position sensor responsive to the position of said ram for providing a signal correlated to the position of said ram in said barrel, control means connected to said position sensor for generating a control signal when said ram reaches said forward position, said control signal being coupled to said ram drive means for terminating said ram advancing motion when said ram reaches said forward position, ram holding means connected in forcetransmitting relationship with said ram and responsive to said control signal for holding said ram in said forward position during at least a portion of the time plasticized material injected into said cavity solidifies, sample means responsive to said control signal for sampling the output signal of said pressure transducer to produce a sampled pressure signal when said ram advancement has substantially terminated at said fixed forward position and injected plastic material in said orifice has not yet solidified, whereby the sampled pressure signal is correlated to the pressure in said cavity and hence to the mass of injected material, reference signal means for providing a reference signal correlated to a predetermined barrel pressure, correction means including a comparator responsive to said sampled pressure signal and said reference signal for producing a retraction point correction signal, and means responsive to said retraction point correction signal for varying said retracted position from which said ram advances to inject plasticized material into said cavity to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure at the conclusion of injection of the preceding charge.
Claim 3
Dependent Claim
54 words
The apparatus of claim 1 wherein said control means further include: a reference potential source for providing a reference potential correlated to said fixed forward position, and a comparator connected to said position sensor and said fixed forward position reference source for generating said control signal when said ram reaches said fixed forward position.
Claim 4
Dependent Claim
263 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, said ram being reciprocated between a variable retracted position and a fixed forward position, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: hydraulic pressure means for advancing said ram, electrically responsive valve means for controlling said hydraulic pressure means, a transducer responsive to the pressure of material in said barrel upstream of said orifice, a sensor responsive to the position of said ram, means responsive to said sensor for actuating said valve means to reduce the pressure in said hydraulic pressure means and stop said ram when said ram reaches said fixed forward position, a reference signal source for providing a reference signal correlated to the pressure in said barrel which exists when said cavity has been charged with a predetermined mass of plasticized material, sample means responsive to said position sensor, said reference signal source and said transducer for comparing said reference pressure signal and said barrel pressure transducer signal when said ram has substantially stopped and the plasticized material in said orifice has not yet solidified for producing a sampled barrel pressure signal, and means responsive to said sampled barrel pressure signal provided by said sample means for controlling the retracted position of said ram during the succeeding charge injecting cycle in a manner dependent on the relationship of said barrel pressure and said reference pressure.
Claim 5
Dependent Claim
263 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, said ram being reciprocated between a variable retracted position and a fixed forward position, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: hydraulic pressure means for advancing said ram, electrically responsive valve means for controlling said hydraulic pressure means, a transducer responsive to the pressure of material in said barrel upstream of said orifice, a sensor responsive to the position of said ram, means responsive to said sensor for actuating said valve means to reduce the pressure in said hydraulic pressure means and stop said ram when said ram reaches said fixed forward position, a reference signal source for providing a reference signal correlated to the pressure in said barrel which exists when said cavity has been charged with a predetermined mass of plasticized material, sample means responsive to said position sensor, said reference signal source and said transducer for comparing said reference pressure signal and said barrel pressure transducer signal when said ram has substantially stopped and the plasticized material in said orifice has not yet solidified for producing a sampled barrel pressure signal, and means responsive to said sampled barrel pressure signal provided by said sample means for controlling the retracted position of said ram during the succeeding charge injecting cycle in a manner dependent on the relationship of said barrel pressure and said reference pressure.
Claim 6
Dependent Claim
96 words
The apparatus of claim 3 wherein said sample means includes: velocity means responsive to said position sensor for producing a velocity signal correlated to the velocity of said ram, predetermined velocity detecting means responsive to said velocity means for producing a trigger signal when said ram velocity reaches a predetermined value, means responsive to said ram position sensor for producing an injection-finished signal when said ram reaches said fixed forward position, and means responsive to said trigger signal and said injection finished signal for samplinG said barrel pressure when said ram reaches said fixed forward position.
Claim 7
Dependent Claim
25 words
The apparatus of claim 4 wherein said predetermined velocity detecting means includes a reference potential source for providing a signal correlated to said predetermined velocity.
Claim 8
Dependent Claim
383 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, said ram being reciprocated between a variable retracted position and a fixed forward position and being rotatable to accumulate a charge forward of the tip of said ram, and a signal-responsive ram drive for reciprocating and rotating said ram, a control system for said ram drive designed to promote uniform charging of said cavity, said control system comprising: a transducer responsive to the pressure of material in said barrel upstream of said orifice for providing a signal correlated to barrel pressure, a sensor responsive to the position of said ram for providing a ram-position signal, first reference signal generating means for establishing first and second reference signals correlated to a specified retracted position for said ram and said fixed forward position, respectively, means including a comparator responsive to said ram position signal and said first reference signal for generating a ram rotation termination signal useful when input to said ram drive for terminating rotation of said ram when said ram position signal and said first reference signal are in a predetermined relation, means including a comparator responsive to said ram position signal and said second reference signal for generating a ram advance termination signal useful when input to said ram drive for terminating advancement of said ram when said ram-position signal and said second reference signal are in a predetermined relation, second reference signal generating means for establishing a third reference signal corresponding to a barrel pressure associated with a specified desired injection charge, and means responsive to said transducer and said second reference signal means for comparing said transducer pressure signal and third reference signal when said ram advancement has substantially terminated and injected material in said orifice has not yet solidified, said comparison means being connected to said first reference signal means for modifying said first reference signal to thereby vary said retracted position from which said ram advances to inject plasticized material into said cavity, and in turn vary the mass of the succeeding charge of injected material, in a manner dependent on barrel pressure existing at the conclusion of the preceding charge injection cycle.
Claim 9
Dependent Claim
383 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, said ram being reciprocated between a variable retracted position and a fixed forward position and being rotatable to accumulate a charge forward of the tip of said ram, and a signal-responsive ram drive for reciprocating and rotating said ram, a control system for said ram drive designed to promote uniform charging of said cavity, said control system comprising: a transducer responsive to the pressure of material in said barrel upstream of said orifice for providing a signal correlated to barrel pressure, a sensor responsive to the position of said ram for providing a ram-position signal, first reference signal generating means for establishing first and second reference signals correlated to a specified retracted position for said ram and said fixed forward position, respectively, means including a comparator responsive to said ram position signal and said first reference signal for generating a ram rotation termination signal useful when input to said ram drive for terminating rotation of said ram when said ram position signal and said first reference signal are in a predetermined relation, means including a comparator responsive to said ram position signal and said second reference signal for generating a ram advance termination signal useful when input to said ram drive for terminating advancement of said ram when said ram-position signal and said second reference signal are in a predetermined relation, second reference signal generating means for establishing a third reference signal corresponding to a barrel pressure associated with a specified desired injection charge, and means responsive to said transducer and said second reference signal means for comparing said transducer pressure signal and third reference signal when said ram advancement has substantially terminated and injected material in said orifice has not yet solidified, said comparison means being connected to said first reference signal means for modifying said first reference signal to thereby vary said retracted position from which said ram advances to inject plasticized material into said cavity, and in turn vary the mass of the succeeding charge of injected material, in a manner dependent on barrel pressure existing at the conclusion of the preceding charge injection cycle.
Claim 10
Dependent Claim
304 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive for cyclically moving said ram toward and away from said orifice between an adjustably variable retracted position and a fixed forward position to inject an adjustably variable charge of material into said cavity dependent upon said retracted position, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, trigger means responsive to the movement of said ram for providing a signal when said ram has substantially terminated its movement toward said orifice, sample means responsive to said trigger means and said pressure transducer for sampling the output signal of said pressure transducer when said ram has substantially terminated its movement toward said orifice and said plastic material in said orifice has not yet solidified, whereby the saMpled signal is correlated to the pressure in said cavity when said ram is substantially motionless and hence to the mass of material injected into said cavity, reference signal generating means for producing a reference signal correlated to a predetermined barrel pressure, and control means responsive to said sampled signal and said reference signal for providing a ram drive correction signal, said correction signal being input to said ram drive for adjustably varying said retracted position from which said ram advances to inject plasticized material into said cavity to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure at the conclusion of the preceding charge injection cycle.
Claim 11
Dependent Claim
304 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrel, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive for cyclically moving said ram toward and away from said orifice between an adjustably variable retracted position and a fixed forward position to inject an adjustably variable charge of material into said cavity dependent upon said retracted position, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, trigger means responsive to the movement of said ram for providing a signal when said ram has substantially terminated its movement toward said orifice, sample means responsive to said trigger means and said pressure transducer for sampling the output signal of said pressure transducer when said ram has substantially terminated its movement toward said orifice and said plastic material in said orifice has not yet solidified, whereby the saMpled signal is correlated to the pressure in said cavity when said ram is substantially motionless and hence to the mass of material injected into said cavity, reference signal generating means for producing a reference signal correlated to a predetermined barrel pressure, and control means responsive to said sampled signal and said reference signal for providing a ram drive correction signal, said correction signal being input to said ram drive for adjustably varying said retracted position from which said ram advances to inject plasticized material into said cavity to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure at the conclusion of the preceding charge injection cycle.
Claim 12
Dependent Claim
149 words
The system of claim 7 wherein: said control means includes a source of reference potential correlated to said retracted ram position, said reference potential source being selectively variable to increase or decrease said reference potential a fixed-size increment once per ram cycle, said reference potential being increased or decreased one fixed-size increment when said sampled barrel pressure is below or above, respectively, a value correlated to the desired cavity injection charge, said trigger means includes a position transducer responsive to the position of said ram, and wherein said control means further includes means responsive to said position transducer and said retracted ram position reference potential source for adjusting said retracted position in a fixed-size increment once per ram cycle, said adjustment being made each cycle subsequent to said ram reaching said forward position in the preceding cycle and prior to said ram reaching said retracted position the succeeding cycle.
Claim 13
Dependent Claim
109 words
The apparatus of claim 8 wherein said control means further includes retraction means responsive to the movement of said ram for providing a retraction-completed signal when said ram has completed retraction, correction means for alternatively increasing and decreasing said retraction reference potential in fixed-size increments, comparison means responsive to said sampled pressure signal and said reference pressure signal for comparing said signals and providing an output correlated thereto, and means connected to said pressure comparison means and said correction means for controlling said correction means to alternatively produce increasing and decreasing retraction reference potential corrections in dependence upon the comparison between said sampled barrel pressure and said predetermined pressure.
Claim 14
Dependent Claim
277 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrle, said ram being reciprocated between a retracted position and a forward position, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive for advancing said ram toward said orifice through an adjustable length stroke, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, trigger means responsive to the movement of said ram for providing a signal when the ram velocity is at a predetermined level correlated to a predetermined dynamic barrel pressure, sample means responsive to said trigger means and said pressure transducer for sampling the output signal of said pressure transducer following charge injection when the dynamic pressure of plasticized material in said barrel is at said predetermined level and said plastic material in said cavity and hence to the mass of injected material, reference signal generating means for producing a reference signal correlated to a predetermined barrel pressure, and control means responsive to said sampled pressure signal and Said reference signal for providing a ram drive correction signal, said correction signal being input to said ram drive for varying the length of the succeeding ram stroke inversely to the magnitude of said sampled pressure to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure existing upon conclusion of the preceding charge injection cycle.
Claim 15
Dependent Claim
277 words
In an injection molding machine having a reciprocating ram for injecting a charge of plasticized material from an injection barrel into a mold cavity via an orifice located at the downstream end of said barrle, said ram being reciprocated between a retracted position and a forward position, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive for advancing said ram toward said orifice through an adjustable length stroke, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, trigger means responsive to the movement of said ram for providing a signal when the ram velocity is at a predetermined level correlated to a predetermined dynamic barrel pressure, sample means responsive to said trigger means and said pressure transducer for sampling the output signal of said pressure transducer following charge injection when the dynamic pressure of plasticized material in said barrel is at said predetermined level and said plastic material in said cavity and hence to the mass of injected material, reference signal generating means for producing a reference signal correlated to a predetermined barrel pressure, and control means responsive to said sampled pressure signal and Said reference signal for providing a ram drive correction signal, said correction signal being input to said ram drive for varying the length of the succeeding ram stroke inversely to the magnitude of said sampled pressure to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure existing upon conclusion of the preceding charge injection cycle.
Claim 16
Dependent Claim
132 words
The system of claim 10 wherein said ram drive moves between a fixed forward position and an adjustable retracted position, and wherein said reference signal means includes a reference signal source for providing a reference signal correlated to the static barrel pressure associated with the desired mold charge, and wherein said control means includes a comparator responsive to said pressure transducer and said trigger means for comparing said sampled barrel pressure signal to said reference pressure signal when said ram velocity is at said predetermined level and in response to said comparison generates a correction signal for application to said ram drive to vary said retracted position in the succeeding cycle dependent on static pressure in said barrel and hence in said cavity at the conclusion of the preceding charge injection cycle.
Claim 17
Dependent Claim
348 words
In an injection molding machine having a rotatable ram screw for accumulating and injecting a charge of plasticized material from an injection barrel into aa mold cavity via an orifice located at the downstream end of said barrel, said ram being rotated to accumulate a charge forward of the tip thereof beteen a fixed forward position and variable retracted position and reciprocated to inject said accumulated charge into said cavity, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive for rotating said ram through an adjustable charge-accumulating distance between a fixed forward position and a variable retracted position and for subsequently advancing said ram through said distance to inject said accumulated charge into said cavity via said orifice, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, trigger means responsive to the movement of said ram for providing a signal when the ram velocity is at a predetermined level correlated to a predetermined dynamic barrel pressure, sample means responsive to said trigger means and said pressure transducer for sampling the output signal of said pressure transducer following charge injection when the dynamic pressure of plasticized material in said barrel at said predetermined level and said plastic material in said orifice has not yet solidified, whereby the sampled pressure signal is correlated to the pressure in said cavity and hence to the mass of injected material, reference signal generating means for generating a reference signal correlated to a predetermined barrel pressure, and control means responsive to said sampled pressure signal and said reference signal for providing a ram drive correction signal, said correction signal being input to a ram drive for varying the distance through which said ram is rotated during the charge-accumulating cycle inversely to the magnitude of the sampled pressure to thereby between the mass of the succeeding charge of injected material in a manner dependent on cavity pressure existing upon conclusion of the preceding charge injection cycle.
Claim 18
Dependent Claim
348 words
In an injection molding machine having a rotatable ram screw for accumulating and injecting a charge of plasticized material from an injection barrel into aa mold cavity via an orifice located at the downstream end of said barrel, said ram being rotated to accumulate a charge forward of the tip thereof beteen a fixed forward position and variable retracted position and reciprocated to inject said accumulated charge into said cavity, a control system for said ram designed to promote uniform charging of said cavity, said control system comprising: a signal-controlled ram drive for rotating said ram through an adjustable charge-accumulating distance between a fixed forward position and a variable retracted position and for subsequently advancing said ram through said distance to inject said accumulated charge into said cavity via said orifice, a pressure transducer communicating with said barrel upstream of said orifice for providing a signal correlated to the pressure of plasticized material in said barrel, trigger means responsive to the movement of said ram for providing a signal when the ram velocity is at a predetermined level correlated to a predetermined dynamic barrel pressure, sample means responsive to said trigger means and said pressure transducer for sampling the output signal of said pressure transducer following charge injection when the dynamic pressure of plasticized material in said barrel at said predetermined level and said plastic material in said orifice has not yet solidified, whereby the sampled pressure signal is correlated to the pressure in said cavity and hence to the mass of injected material, reference signal generating means for generating a reference signal correlated to a predetermined barrel pressure, and control means responsive to said sampled pressure signal and said reference signal for providing a ram drive correction signal, said correction signal being input to a ram drive for varying the distance through which said ram is rotated during the charge-accumulating cycle inversely to the magnitude of the sampled pressure to thereby between the mass of the succeeding charge of injected material in a manner dependent on cavity pressure existing upon conclusion of the preceding charge injection cycle.
Claim 19
Independent Claim
320 words
A method of charging, with a uniform mass of injected plasticized material, a molding cavity having an orifice which communicates with an injection barrel in which a ram reciprocates under control of a signal-controlled drive means between a fixed forward position and a variable retracted position, said method comprising: generating a signal correlated to the barrel pressure with a pressure transducer connected to be responsive to barrel pressure, generating a Signal correlated to the position of said ram with a position transducer responsive to ram position, generating first and second reference signals with a voltage source correlated to a selected retracted position and said fixed forward position, respectively, electrically comparing said ram position and first reference signals in a comparator and providing a retraction termination signal when said ram position and first reference signals are in a predetermined position, automatically terminating retraction of said ram and initiating ram advance under control of said retraction termination signal when said ram position signal and said first reference signal are in a predetermined relation, electrically comparing said ram position and second reference signals in a comparator and providing an advancement termination signal when said ram position signal and said second reference signals are in a predetermined relation, automatically terminating advancement of said ram under control of said advancement termination signal when said ram position signal and said second reference signal are in a predetermined relation, establishing a third reference signal with a voltage source corresponding to a barrel pressure associated with a specified desired injection charge, electrically comparing said barrel pressure signal and said third reference signal at the conclusion of charge injection when said ram advancement toward said orifice has substantially terminated and producing a correction signal in response thereto, and automatically modifying said first reference signal with said correction signal to thereby vary the position to which said ram subsequently retracts, and hence to vary the size of the succeeding charge.
Claim 20
Independent Claim
320 words
A method of charging, with a uniform mass of injected plasticized material, a molding cavity having an orifice which communicates with an injection barrel in which a ram reciprocates under control of a signal-controlled drive means between a fixed forward position and a variable retracted position, said method comprising: generating a signal correlated to the barrel pressure with a pressure transducer connected to be responsive to barrel pressure, generating a Signal correlated to the position of said ram with a position transducer responsive to ram position, generating first and second reference signals with a voltage source correlated to a selected retracted position and said fixed forward position, respectively, electrically comparing said ram position and first reference signals in a comparator and providing a retraction termination signal when said ram position and first reference signals are in a predetermined position, automatically terminating retraction of said ram and initiating ram advance under control of said retraction termination signal when said ram position signal and said first reference signal are in a predetermined relation, electrically comparing said ram position and second reference signals in a comparator and providing an advancement termination signal when said ram position signal and said second reference signals are in a predetermined relation, automatically terminating advancement of said ram under control of said advancement termination signal when said ram position signal and said second reference signal are in a predetermined relation, establishing a third reference signal with a voltage source corresponding to a barrel pressure associated with a specified desired injection charge, electrically comparing said barrel pressure signal and said third reference signal at the conclusion of charge injection when said ram advancement toward said orifice has substantially terminated and producing a correction signal in response thereto, and automatically modifying said first reference signal with said correction signal to thereby vary the position to which said ram subsequently retracts, and hence to vary the size of the succeeding charge.
Claim 21
Independent Claim
215 words
A method of charging, with a uniform mass of injected plasticized material, a molding cavity having an orifice which communicates with an injection barrel in which a ram reciprocates through a stroke length between forward and retracted positions, said method comprising: generating a signal correlated to the barrel pressure with a pressure transducer responsive to barrel pressure, generating a signal correlated to the desired stroke length of said ram with a variable magnitude voltage source, driving said ram through said desired stroke in response to said stroke length signal to inject a charge into said cavity via said orifice, monitoring ram movement, automatically sampling said barrel pressure signal upon conclusion of charge injection when the ram has completed said desired stroke as determined by monitoring its movement and the dynamic pressure of plasticized material in said barrel is approximately zero and said injected plastic material in said orifice has not yet solidified, whereby the sampled pressure signal is correlated to the pressure in said cavity and hence to the mass of injected material, and correcting said stroke length signal with said sampled pressure signal, the correction being made inversely to the magnitude of said sampled pressure to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure.
Claim 22
Independent Claim
215 words
A method of charging, with a uniform mass of injected plasticized material, a molding cavity having an orifice which communicates with an injection barrel in which a ram reciprocates through a stroke length between forward and retracted positions, said method comprising: generating a signal correlated to the barrel pressure with a pressure transducer responsive to barrel pressure, generating a signal correlated to the desired stroke length of said ram with a variable magnitude voltage source, driving said ram through said desired stroke in response to said stroke length signal to inject a charge into said cavity via said orifice, monitoring ram movement, automatically sampling said barrel pressure signal upon conclusion of charge injection when the ram has completed said desired stroke as determined by monitoring its movement and the dynamic pressure of plasticized material in said barrel is approximately zero and said injected plastic material in said orifice has not yet solidified, whereby the sampled pressure signal is correlated to the pressure in said cavity and hence to the mass of injected material, and correcting said stroke length signal with said sampled pressure signal, the correction being made inversely to the magnitude of said sampled pressure to thereby vary the mass of the succeeding charge of injected material in a manner dependent on cavity pressure.
Claim 23
Independent Claim
345 words
A method of charging, with a uniform mass of injected plasticized material, a molding cavity having an orifice which communicates with an injection barrel in which a rotatable ram screw rotates under control of a signal-controlled drive means to accumulate a charge forward of the tip thereof and where said ram reciprocates toward said orifice to inject said accumulated charge into said cavity, said method comprising: generating a signal correlated to the barrel pressure with a pressure transducer connected to be responsive to barrel pressure, generating a signal correlated to the position of said ram screw with a position transducer responsive to ram position, generating first and second reference signals with a voltage source correlated to a correctible retracted position and a fixed forward position, electRically comparing ram screw position signal and said first reference signal and providing a rotation termination signal when said ram screw position signal and said first reference signal are in a predetermined relation, automatically terminating rotation of said ram screw under control of said rotation termination signal when said ram screw position signal and said first reference signal are in said predetermined relation, electrically comparing said ram screw position signal and said second reference signal and providing a ram screw reciprocation termination signal when said position signal and said second reference signal are in a predetermined relationship, automatically terminating reciprocation of said ram screw toward said orifice under control of said reciprocation termination signal when said ram screw position signal and said second reference signal are in a predetermined relation, establishing a third reference signal with a voltage source corresponding to a barrel pressure associated with a specified desired injection charge, electrically comparing said barrel pressure signal and said third reference signal at the conclusion of charge injection when said ram reciprocation toward said orifice has substantially terminated and producing a correction signal in response thereto, and automatically modifying said first reference signal with said correction signal to thereby vary the position at which said ram screw subsequently stops rotating, and hence to vary the size of the succeeding charge.
Claim 24
Independent Claim
345 words
A method of charging, with a uniform mass of injected plasticized material, a molding cavity having an orifice which communicates with an injection barrel in which a rotatable ram screw rotates under control of a signal-controlled drive means to accumulate a charge forward of the tip thereof and where said ram reciprocates toward said orifice to inject said accumulated charge into said cavity, said method comprising: generating a signal correlated to the barrel pressure with a pressure transducer connected to be responsive to barrel pressure, generating a signal correlated to the position of said ram screw with a position transducer responsive to ram position, generating first and second reference signals with a voltage source correlated to a correctible retracted position and a fixed forward position, electRically comparing ram screw position signal and said first reference signal and providing a rotation termination signal when said ram screw position signal and said first reference signal are in a predetermined relation, automatically terminating rotation of said ram screw under control of said rotation termination signal when said ram screw position signal and said first reference signal are in said predetermined relation, electrically comparing said ram screw position signal and said second reference signal and providing a ram screw reciprocation termination signal when said position signal and said second reference signal are in a predetermined relationship, automatically terminating reciprocation of said ram screw toward said orifice under control of said reciprocation termination signal when said ram screw position signal and said second reference signal are in a predetermined relation, establishing a third reference signal with a voltage source corresponding to a barrel pressure associated with a specified desired injection charge, electrically comparing said barrel pressure signal and said third reference signal at the conclusion of charge injection when said ram reciprocation toward said orifice has substantially terminated and producing a correction signal in response thereto, and automatically modifying said first reference signal with said correction signal to thereby vary the position at which said ram screw subsequently stops rotating, and hence to vary the size of the succeeding charge.
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) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |