Injection Molding Cavity Volume Control for Cycle Time Reduction
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Solution Overview
Problem
The existing injection molding systems have a significant drawback in terms of cycle time, particularly for manufacturing PET preforms, where the cool cycle contributes substantially to the overall cycle time, and there is a need to reduce this duration to enhance productivity.
Innovation Solution
The proposed solution involves overlaying the functions of the cool cycle with other molding-system operations by managing the internal pressure of the PET preform through physical methods, such as altering the effective volume of the mold cavity, to reduce the cool cycle time and achieve parallel execution of certain operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mold cavity volume is reduced after injection to compress the resin and compensate for cooling-induced shrinkage, then the manufacturing precision is improved, but the cycle time increases due to the additional compression step
Solution Approach 1:
The patent combines the cooling function and compression function into a single integrated process. The mold cavity serves dual purposes: as a cooling chamber and as a compression device. By reducing the mold cavity volume after injection, the system simultaneously cools the resin and compresses it to compensate for shrinkage, eliminating the need for separate cooling and compression steps.
Solution Approach 2:
The mold cavity is designed to perform multiple functions: it acts as both a cooling chamber and a compression device. The movable mold portion can change the cavity volume to provide compression while the cooling system operates, making the mold cavity a multi-functional component that handles both thermal management and dimensional control.
2Manufacturing precision
If the cool cycle time is extended to ensure proper cooling of the resin, then the manufacturing precision is improved, but the productivity decreases
Solution Approach 1:
The patent merges the cooling process with the compression process by reducing the mold cavity volume during cooling. This allows the resin to be cooled and compressed simultaneously, reducing the total time required while maintaining both cooling uniformity and dimensional accuracy.
Solution Approach 2:
The compression action is applied during the cooling process rather than after cooling is complete. By preliminarily compressing the resin while it is still in the mold cavity during cooling, the system prepares the part for ejection without requiring an additional post-cooling compression step.
3Ease of operation
If the mold cavity volume is altered to manage internal pressure of the resin, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The mold cavity volume is made dynamic rather than static. The movable mold portion can change the cavity volume during the molding process to control resin pressure. This dynamic adjustment allows for better pressure management during injection and cooling, improving ease of operation despite the added mechanical complexity.
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 results in a reduction of the overall cycle time of the injection molding system, allowing for faster production and improved efficiency by minimizing the cool cycle duration.
Implementation Method 1
The molding material thus injected is cooled inside the mold cavity
Implementation Method 2
the internal pressure of the molded article is reduced, by altering the effective volume of the mold cavity, to a level that permits opening of the mold
Data Source
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AI summary
According to the present invention, there is provided a molding system (100) configured to manufacture a molded article (103) by using a molding material (101). The molding system (100) comprises a mold-cavity system (200) for forming, in use, the molded article (103). The mold-cavity system (200) includes a primary parting line (224) defined between a cavity portion (210) and a neck portion (206), a secondary parting line (222) defined between the neck portion (206) and a top portion (204), and a controller (160) operatively coupling to a mold-moving actuator. The controller (160) has a controller-usable memory (162) tangibly embodying a set of controller-executable instructions (500). The set of controller-executable instructions (500) are configured to direct the controller (160), and include mold-open instructions (902) configured to cause initial separation of the top portion (204) and the neck portion (206) relative to the secondary parting line (222), while keeping the primary parting (224) line un-opened, while maintaining at least some clamp force.