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EP0461627A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Injection molding controller with controlled variable learning

Assignee: Allen Bradley Co LLC
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Filing: 1991-06-12
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Granted: —
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Expires: 2011-06-12
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Abstract

Abstract A controller for an injection molding machine controls the injection ram by means of profiles (350) having segments with programmable setpoints. The injection molding machine is initially controlled during each segment in an open-loop manner (354). Closed-loop control (352) is then adopted. The difference between the open-loop (OLCV) and the closed-loop (CLCV) output to the injection molding machine valves (36, 38) is used to change the setpoints with each cycle to improve the open-loop accuracy over time. The learning (353) rate of change of the open-loop setpoints decreases after the initial correction. During the open-loop control (354), the closed-loop control (352) is deactivated to prevent it from being affected by the previous open-loop error.

Inventors

  • 👤 James William Stroud Iii
  • 👤 John Frank Dodds

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 13:19
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/39; B; B29; B29C; B29C45/00; B29C45/17; B29C45/76

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 265 words
A controller for use with an injection molding machine having a ram to inject plastic material into a mold cavity during at least one stage of an injection molding cycle, the injection molding machine having a valve for receiving a control signal and controlling the ram and a transducer for producing a process signal related to the response of the ram to the control signal, the controller comprising: a memory (350) for storing a profile for a stage comprised of a plurality of segments each associated with a setpoint; a segment pointer (360) for addressing the memory and identifying a current segment and its setpoint and for producing a transition signal at the end of a segment; an open-loop control means (354) for receiving the current setpoint determined by the segment pointer and converting it to a first control signal (OLCV) for controlling the valve (36, 38) during a first period during the current segment; a closed-loop control means (352) for receiving the process signal (15, 17, 33) from the injection molding machine and the current setpoint determined by the segment pointer to produce a second control signal (CLCV) for controlling the valve (36, 38) during a second period during the current segment and after the first period; and a setpoint correcting means (353) responsive to the transition signal to compare the first control signal (OLCV) to the second control signal (CLCV) and to correct the current setpoint in the memory (350) to reduce the difference between the first control signal and the second control signal for that segment during the next injection molding cycle.
Claim 2
Dependent Claim 15 words
The controller of claim 1 wherein the process signal is the mold cavity pressure (33).
Claim 3
Dependent Claim 14 words
The controller of claim 1 wherein the process signal is the ram pressure (17).
Claim 4
Dependent Claim 56 words
The controller of claim 1, 2 or 3, wherein the setpoint correcting means (353) reduces the difference between the first control signal (OLCV) and the second control signal (CLCV) by adding a correction amount to the current setpoint equal to a learning factor times the difference between the second control signal and the first control signal.
Claim 5
Dependent Claim 17 words
The controller of claim 4 wherein the learning factor is reduced for subsequent repetitions of the stage,
Claim 6
Dependent Claim 21 words
The controller of claim 4 or 5 wherein the learning factor has a maximum of 100% and a minimum of 25%.
Claim 7
Dependent Claim 42 words
The controller of any one of the claims 1 to 6 wherein the closed-loop control means (352) includes an integrator responsive to the difference between the current setpoint and the injection pressure and wherein the integrator is disabled during the first period.

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