Movable Insert Cooling in Thermoplastic Molding
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Solution Overview
Problem
Existing mold designs for thermoplastic container production, particularly those of the portfolio type, face challenges in effectively cooling movable inserts used to form recesses like handles, leading to material overheating and shape inconsistencies due to inadequate thermal regulation.
Innovation Solution
A molding unit with a movable insert pierced with channels, where the insert is fixed on a piston with a screw, and the channels are in fluid communication through a primary and secondary chamber system, allowing for efficient thermal regulation using a pressurized fluid for cooling, eliminating the need for complex external cooling circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a movable insert is used to form recesses like handles in containers, then the container can have functional features such as integrated handles, but the insert heats up to temperatures around 100°C during repeated contact with the blank material, causing the material to remain above the glass transition temperature and deform after degassing
Solution Approach 1:
The cooling system is segmented into multiple independent channels drilled directly into the insert, allowing targeted cooling of specific hot zones without requiring a complex external cooling circuit. This segmentation enables efficient heat removal from the insert while maintaining the ability to form complex container shapes.
Solution Approach 2:
A cooling fluid acts as an intermediary medium, circulating through channels in the insert to transfer heat from the hot insert surface to the cooling fluid, thereby maintaining the insert temperature below the glass transition temperature of the blank material and preventing deformation.
2Temperature
If a cooling circuit with channels is made in the insert with flexible hoses and solenoid valves, then the insert can be cooled, but the design becomes cumbersome and is unsuitable for clamshell molds where space is limited
Solution Approach 1:
The cooling channels are merged directly into the insert structure itself, eliminating the need for separate flexible hoses and external cooling circuits. This integration simplifies the overall design, reduces the number of components, and makes the system suitable for compact clamshell mold configurations.
Solution Approach 2:
The insert serves its own cooling needs through internally drilled channels that are self-contained within the insert structure, eliminating the requirement for complex external cooling systems with multiple valves and flexible connections.
3Manufacturing precision
If the blank material contacts the hot insert, then the material remains malleable and can be shaped, but it does not have enough time to cool and solidify before degassing, causing shape inconsistencies
Solution Approach 1:
The cooling channels are pre-configured within the insert structure, and cooling fluid is continuously circulated to maintain the insert temperature below the glass transition temperature of the blank material. This preliminary cooling action ensures that the material solidifies quickly upon contact with the insert, preventing deformation during the brief degassing period.
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 solution enables effective cooling of the inserts, ensuring the material freezes properly before degassing, reducing shape inconsistencies and allowing for the production of containers with precise, desired shapes, even in compact mold designs.
Implementation Method 1
the insert being pierced with channels; a piston on which the insert is fixed and which ensures the mobility of the latter between its retracted position and its deployed position, this piston being itself mounted in translation in a recess cut in the side wall, the piston defining a primary fluidic chamber located on the side of the piston opposite the insert and into which opens at least one conduit for supplying a pressurized fluid, made in the side wall
Implementation Method 2
At least one screw by which the insert is fixed on the piston. The insert channels are in fluidic communication with the primary chamber via a fluidic circuit which includes at least a first section formed in the screw and which communicates with the insert channels, and a second section formed in the piston, which communicates with the first section
Data Source
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AI summary
Molding unit (1) for forming a container (2), this forming unit (1) comprising: - A mold (5) having a lateral wall (6) defining a cavity (7) in the shape of a part of the container (2); - An insert (12) having a front face (13) in the shape of a local part of the container (2), movable between a retracted position and a deployed position, this insert (12) being pierced with channels (52); - A drilled piston (17) on which the insert (12) is fixed and which ensures the mobility of the latter between its retracted position and its deployed position; - At least one drilled screw (31) by which the insert (12) is fixed on the piston (17).