Rotational Force Detection for Check Ring Closing in Injection Molding
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Solution Overview
Problem
Existing injection molding machines face challenges in precisely detecting the closing point of the check ring, leading to variations in injection capacity and molded article quality due to backflow issues, which are not effectively addressed by existing pressure sensors or complex mechanisms.
Innovation Solution
An injection molding machine with rotational force detecting means to identify the peak rotational force time as the closing point of the check ring, allowing for precise detection and adjustment of molding conditions without requiring special mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is provided rearward from the check ring to detect resin pressure, then the closing motion of the check ring can be detected, but the detection precision deteriorates due to indirect detection without direct contact with resin, and the sensor requires complex positioning and maintenance
Solution Approach 1:
The patent replaces the mechanical pressure sensor system with a rotational force detection system. Instead of using a pressure sensor that indirectly detects resin pressure through mechanical coupling, the invention directly detects the rotational force acting on the screw during injection, which provides a more direct and precise measurement of the check ring closing moment without complex positioning requirements
Solution Approach 2:
The patent introduces rotational force as an intermediary parameter to detect check ring closing. Rather than directly measuring pressure (which requires complex sensor positioning) or directly observing the check ring (which is mechanically complex), the invention uses rotational force as a measurable intermediary that reflects the closing state without requiring direct contact or complex instrumentation
2Reliability
If the check ring closing timing is varied due to remaining pressure in the groove, then the injection capacity varies between cycles, but adding complex detection mechanisms increases device complexity and cost
Solution Approach 1:
The patent implements feedback control by detecting the actual check ring closing timing through rotational force measurement and using this information to adjust molding parameters. The system continuously monitors rotational force during injection, identifies the peak moment corresponding to check ring closing, and uses this feedback to ensure consistent injection capacity across cycles
Solution Approach 2:
The patent changes the detection parameter from indirect pressure measurement to direct rotational force measurement. By monitoring rotational force rather than pressure, the system can accurately detect the check ring closing moment without being affected by remaining pressure in the groove, thereby stabilizing injection capacity without adding complex detection mechanisms
3Measurement precision
If pressure sensors are used to detect check ring closing, then closing motion can be monitored, but the sensors require periodic maintenance and calibration, increasing operational complexity
Solution Approach 1:
The patent applies self-service by using the screw's own rotational motion to generate the detection signal. The rotational force detecting means measures the rotational force already acting on the screw during normal injection operation, eliminating the need for separate pressure sensors that would require maintenance and calibration. The system uses the existing mechanical energy of the screw rotation itself as the detection basis
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise detection of the check ring closing point, improving the consistency of injection molding by accurately determining the quality of molded articles and adjusting molding conditions, thereby enhancing the reliability and quality of the molding process.
Implementation Method 1
The resin pellet is melted by shearing heat generated when the screw 1 rotates
Implementation Method 2
The molten resin increases a resin pressure behind the check ring 3 and generates a force for pushing the check ring 3 forward
Implementation Method 3
rotational force detecting means for detecting a rotational force acting on the screw
Data Source
AI summary
If a screw is moved forward after a metering step is completed, the screw moves in a state where a check ring on a tip end of the screw is in open state. Resin flows in a direction opposite to the injection direction. A rotational force is applied to the screw due to the backflow of the resin. If the check ring closes a resin passage, the rotational force acting on the screw is reduced. A peak time of the screw rotational force is detected as closing point in time of the check ring. Physical amounts such as a screw rotational force and a screw position at that timing are detected. Since the closing point in time of the check ring is precisely detected, correction of the injection/hold pressure switching position and the injection speed switching position can be adjusted more precisely. It is possible to precisely determine whether a molded article is non-defective or defective based on the detected physical amount.