Injection Molding Control Using Mold Opening Feedback
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Solution Overview
Problem
Injection molding machines face challenges in selecting appropriate molding conditions to prevent defects such as burrs and dimensional issues due to difficulties in controlling clamping force and dwell pressure, leading to incomplete mold closure and excessive resin filling.
Innovation Solution
An injection molding machine equipped with a mold opening amount sensor and a controlling unit that adjusts clamping force and dwell pressure based on mold opening amount during the molding cycle, enabling the selection of optimal molding conditions for natural compression to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If clamping force is decreased to enable natural compression, then manufacturing precision is improved through resin compression, but reliability deteriorates due to incomplete mold closure causing burrs and dimensional defects
Solution Approach 1:
The system uses a mold opening amount sensor to detect the actual opening of the mold during the molding cycle, and the control unit adjusts the clamping force based on this feedback. This closed-loop control ensures that even with reduced clamping force for natural compression, the mold remains reliably closed by dynamically compensating for opening tendencies through real-time sensor data.
Solution Approach 2:
The clamping force is transformed from a static fixed value to a dynamic adjustable parameter. The control unit varies the clamping force during the molding cycle based on detected mold opening amounts, allowing the system to adaptively maintain reliable mold closure while enabling natural compression effects.
2Use of energy by moving object
If clamping force is decreased for natural compression, then equipment load is reduced, but manufacturing precision deteriorates due to excessive filling and molding defects
Solution Approach 1:
The mold opening amount sensor provides real-time feedback on mold separation, allowing the control unit to precisely adjust clamping force. This ensures that enough force is applied to prevent excessive filling and molding defects, while still reducing overall equipment load compared to traditional high clamping force methods.
Solution Approach 2:
The system changes the clamping force parameter dynamically during the molding cycle based on detected mold opening amounts. This allows optimization of the balance between equipment load reduction and maintaining sufficient clamping to prevent molding defects, adapting the parameter to actual process conditions.
3Reliability
If clamping force is increased to ensure complete mold closure, then reliability is improved, but manufacturing precision deteriorates due to suppressed natural compression causing sinks and warpage
Solution Approach 1:
The clamping force transitions from a static high constant value to a dynamic time-varying parameter. The control unit reduces clamping force during phases when natural compression is beneficial, while maintaining higher force only when needed for mold closure, thus preventing sinks and warpage while ensuring reliability.
Solution Approach 2:
The system applies periodic modulation to the clamping force during the molding cycle. By rhythmically adjusting force levels based on mold opening detection, it creates periods of reduced clamping that allow natural compression to occur, followed by periods of increased clamping to maintain closure, preventing both defects.
4Manufacturing precision
If high clamping force and dwell pressure are used, then manufacturing precision is maintained, but device complexity increases and mold lifespan decreases
Solution Approach 1:
The system uses the mold's own opening behavior as detected by the sensor to automatically regulate the clamping force. This self-regulating mechanism maintains manufacturing precision through natural compression without requiring complex external control systems or multiple sensors, simplifying overall device complexity.
Solution Approach 2:
A simple feedback loop using a single mold opening amount sensor allows the control unit to automatically maintain optimal clamping force for manufacturing precision. This minimal feedback system achieves precise control without adding significant device complexity compared to traditional open-loop high clamping force methods.
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
The solution allows for the prevention of molding defects like sinks, warpage, internal stress, and dimensional issues by controlling clamping force and dwell pressure, enabling the selection of lower clamping force and dwell pressure settings, which reduces equipment load and extends mold lifespan.
Implementation Method 1
the molds are opened by the internal pressure (mold internal pressure) of resin filling the molds and then is closed by solidification contraction of the resin and elastic recovery of a tie bar so that the resin is compressed
Implementation Method 2
the molds are opened by the internal pressure (mold internal pressure) of resin filling the molds and then is closed by solidification contraction of the resin
Data Source
AI summary
An injection molding machine, and a method of controlling the injection molding machine, can prevent a molding defect. The injection molding machine can mold a product for each execution of a molding cycle through an injecting process of injecting a material into clamped molds, a dwell process of controlling dwell pressure of the material in the molds, and a cooling process of cooling the material in the molds, the injection molding machine including a mold opening amount sensor and a controlling unit, the mold opening amount sensor being configured to detect a mold opening amount of the molds, the controlling unit being configured to control clamping force of the molds and the dwell pressure based on the mold opening amount during the molding cycle.