Bent Introducing Runner for Uniform Preform Thickness
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Solution Overview
Problem
In injection stretch blow molding machines, the advanced timing for releasing preforms leads to reduced cooling time, resulting in uneven thickness of hollow molded bodies due to biased temperature distribution, making it difficult to achieve uniform thickness in the circumferential direction.
Innovation Solution
The hot runner apparatus is modified by bending the introducing runner portion towards the horizontal runner portion and extending it to be continuous with the intermediate portion, allowing the molten resin to branch and distribute evenly, reducing temperature unevenness and ensuring uniform thickness injection into preform molding portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the introducing runner portion is arranged straight from the injection apparatus to the horizontal runner portion, then the structure is simple, but the molten resin creates a higher temperature and lower viscosity portion in a biased manner in the circumferential direction, resulting in uneven thickness of hollow molded bodies
Solution Approach 1:
The introducing runner portion is configured to be bent in plan view, transforming the straight runner path into a curved configuration. This curvature redistributes the molten resin flow pattern, preventing the formation of biased high-temperature low-viscosity regions and ensuring more uniform temperature distribution in the circumferential direction, thereby achieving uniform thickness in hollow molded bodies
Solution Approach 2:
The invention changes the geometric parameter of the introducing runner portion from a straight configuration to a bent configuration in plan view. This parameter change modifies the flow characteristics of the molten resin, eliminating the biased temperature distribution and achieving uniform thickness without increasing structural complexity
2Productivity
If cooling time is reduced by advancing preform release timing, then productivity is improved, but temperature distribution becomes uneven, making it difficult to achieve uniform thickness
Solution Approach 1:
By changing the geometric parameter of the introducing runner portion (from straight to bent), the invention achieves uniform temperature distribution in the preform even with reduced cooling time. This allows advanced preform release timing to be implemented without compromising thickness uniformity, thereby resolving the contradiction between productivity improvement and manufacturing precision
3Manufacturing precision
If the introducing runner portion is bent and extended to be continuous with the intermediate portion, then uniform thickness is achieved, but the runner length increases
Solution Approach 1:
The introducing runner portion is bent in plan view to create a curved path that achieves uniform temperature distribution. While this increases the runner length compared to a straight configuration, the curved design efficiently utilizes the available space and achieves the critical goal of uniform thickness without excessive length increase
Data Source
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AI summary
An aim of the present invention is to enable a molten resin to be fed from a hot runner apparatus into preform molding portions of an injection molding mold without a higher temperature and lower viscosity resin being present in a biased manner and to enable preforms having no biased portion of a higher temperature and lower viscosity resin in their circumferential direction. An introducing runner portion (18) of a hot runner apparatus (9) is bent toward a horizontal runner portion (15) after reaching an elevation plane (A) passing through a position of the horizontal runner portion (15) in an up-and-down direction and continuous with an intermediate portion of the horizontal runner portion (15) in the elevation plane (A).