Injection Mold Ejection Ribs for Thin-Walled Article Accuracy
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Solution Overview
Problem
Molded articles with thin-walled or complex geometries are prone to deformation during ejection due to insufficient cooling and require extended cooling times or complex ejection systems, leading to potential defects.
Innovation Solution
Incorporation of ejection-assist features such as helical ejection-assist ribs and retaining features in the mold core design to facilitate controlled ejection by exerting axial forces during unscrewing, reducing deformation and cooling time requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ejection methods are used for thin-walled or complex geometry articles, then the articles can be ejected from the mold, but the articles suffer from deformation during ejection
Solution Approach 1:
The ejection function is segmented into multiple independent ejection pins distributed across the mold core, allowing localized and controlled ejection forces to be applied to different regions of the thin-walled article, preventing deformation that would occur with conventional single-point or uniform ejection methods
Solution Approach 2:
The mold design incorporates preliminary cooling channels and ejection positioning features that prepare the thin-walled article for ejection before the actual ejection process begins, ensuring the article is sufficiently cooled and positioned to resist deformation during ejection
2Manufacturing precision
If extended cooling times are used to prevent deformation, then article quality improves, but production productivity decreases
Solution Approach 1:
The cooling system is segmented into multiple independent cooling zones with separately controllable cooling rates, allowing different regions of the thin-walled article to be cooled at optimized rates that prevent deformation while minimizing total cooling time and maximizing production productivity
Solution Approach 2:
The mold design incorporates variable cooling parameters including adjustable cooling fluid temperature, flow rate, and pressure that can be dynamically changed during the cooling process to optimize both article quality and cooling time for different production requirements
3Manufacturing precision
If complex ejection systems are used to handle thin-walled articles, then ejection accuracy improves, but device complexity increases
Solution Approach 1:
The ejection system is segmented into multiple simple ejection pins rather than one complex ejection mechanism, distributing the ejection function across multiple identical simple components that collectively achieve high ejection accuracy for thin-walled articles while keeping individual component complexity low
Solution Approach 2:
The ejection pins are designed with universal features that allow them to perform multiple functions including ejection, positioning, and support of the thin-walled article, reducing the need for additional specialized components and simplifying the overall ejection system while maintaining high accuracy
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 ejection-assist features help minimize deformation and ejection defects while potentially reducing cooling time and system complexity, enhancing the efficiency and cost-effectiveness of the ejection process.
Implementation Method 1
The ejection-assist rib defines a helical slide surface extending helically about the article axis. During an initial unscrewing rotation of the molded article relative to the mold core, the rib mold feature of the mold core bears against the helical slide surface of the ejection-assist rib to urge the article second portion axially away from the mold core during ejection of the molded article from the mold core.
Data Source
AI summary
An injection molded article includes: (a) an article first portion having internal threading extending helically about an article axis, the threading configured to be formed by a thread mold in a mold core; and (b) an article second portion spaced radially apart from the article first portion and connected to the article first portion by a connection portion. The article second portion has at least one ejection-assist rib configured to be formed by at least one rib mold feature in the mold core. The ejection-assist rib defines a helical slide surface extending helically about the article axis. During an initial unscrewing rotation of the molded article relative to the mold core, the rib mold feature of the mold core bears against the slide surface of the ejection-assist rib to urge the article second portion axially away from the mold core during ejection of the molded article from the mold core.