Injection Molding Screw Controller Backflow Prevention
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Solution Overview
Problem
Existing injection molding machines face challenges in minimizing cycle time and ensuring accurate, uniform resin measurement due to backflow issues during the injection process, which often result in resin dispersion and quality inconsistencies.
Innovation Solution
A controller for injection molding machines that employs distinct retreating speeds for the screw or plunger before and during reverse rotation, allowing for precise control of the resin's pressure and movement to minimize backflow and optimize the measurement process, thereby reducing cycle time and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the screw or plunger is retreated to a measuring point immediately before injection, then the cycle time is shortened, but the molten resin flows backward changing the measured resin amount
Solution Approach 1:
The patent applies preliminary anti-action by implementing a backflow prevention mechanism (check valve or check ring) that is activated in advance before injection starts. This valve prevents the molten resin from flowing backward during the transition from measurement to injection, thereby maintaining the accuracy of the measured resin amount while allowing for shorter cycle times.
2Manufacturing precision
If a check valve or check ring is attached to prevent backflow, then the measured resin amount accuracy is improved, but the molten resin may still flow backward due to delayed valve operation
Solution Approach 1:
The patent applies preliminary action by positioning the check valve or check ring in advance at the distal end of the screw, ready to prevent backflow before injection begins. This pre-positioning ensures that the backflow prevention mechanism is in place and functional before the injection process starts, eliminating delays and ensuring reliable prevention of resin backflow.
3Manufacturing precision
If the screw is reversely rotated to close the resin passage, then the resin backflow is prevented, but the cycle time is extended
Solution Approach 1:
The patent applies the taking out principle by removing the resin passage closure function from the screw's rotational movement. Instead of requiring the screw to reverse rotate to close the passage, a dedicated check valve or check ring is used to perform this function automatically, thereby eliminating the time-consuming reverse rotation step and reducing cycle time while maintaining effective resin passage closure.
Data Source
AI summary
A controller for an injection molding machine capable of reducing an extension of a cycle time in a screw retreat process after the end of measurement, obtaining a more accurate and uniform measured resin amount, and determining measurement conditions in a short period of time. After the measurement is finished, the screw is stopped from rotating and retreated at a first speed V1. The screw is reversely rotated at a predetermined speed Rv in a set zone. As this is done, the screw is retreated at a second speed V2 lower than the first speed V1. After the reverse rotation zone is terminated, the screw is stopped from rotating and retreated at a third speed V3 to a set retreat stop position. By doing this, the cycle time can be made shorter than in the case where the retreat and reverse rotation of the screw are performed separately. Since the retreating speed of the screw is low while the screw is being reversely rotated, a sudden pressure change can be suppressed, so that precise measurement can be made. Since conditions for the reverse rotation and retreat of the screw can be regulated independently, they can be adjusted to optimum conditions in a short period of time.