Stretch Rod Isolation for Liquid Forming Preforms
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Solution Overview
Problem
In the process of forming final-shaped containers using liquids, the gate portions of preforms tend to cool too quickly, leading to incomplete formation or defects in the bottom portions of the containers, as the liquid expansion initiates from the neck and moves towards the bottom, potentially causing malformations or crystallization defects.
Innovation Solution
A method and apparatus that involve forming a preform by injection molding, then stretching it into conformity with a mold cavity using a liquid, where a stretch rod with a deformable or heatable tip is used to isolate the gate portion from the liquid, allowing controlled expansion and heating to prevent premature cooling, ensuring the preform fully forms into the desired shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid is used to stretch the preform during forming, then the container can be filled and formed simultaneously improving productivity, but the gate portion of the preform cools too quickly causing malformations or crystallization defects
Solution Approach 1:
The preform is divided into two zones: the gate portion (lower end) and the body portion. The stretching process is segmented so that the body portion is stretched by liquid pressure while the gate portion is isolated from the liquid and stretched mechanically by the stretch rod, preventing premature cooling and crystallization in the gate area.
Solution Approach 2:
The gate portion is extracted from the liquid stretching environment by introducing a stretch rod that creates a barrier. The liquid is directed to expand the body portion while the stretch rod mechanically stretches the gate portion in isolation, removing it from the harmful cooling effect of the liquid.
Solution Approach 3:
Different stretching mechanisms are applied to different parts of the preform: the body portion undergoes liquid pressure expansion while the gate portion undergoes mechanical stretching by the stretch rod. This local differentiation allows each region to be stretched under appropriate conditions, preventing defects in the gate area while maintaining high productivity.
2Productivity
If the preform is stretched quickly using liquid expansion, then the forming process is faster improving productivity, but the gate portion does not have time to form properly reducing manufacturing precision
Solution Approach 1:
The stretching process is segmented into two independent actions: rapid liquid expansion of the body portion and controlled mechanical stretching of the gate portion by the stretch rod. This allows the body to form quickly while the gate portion receives precise mechanical stretching to achieve proper shape conformity.
Solution Approach 2:
The stretching parameters are changed by introducing the stretch rod that provides mechanical stretching force to the gate portion while the liquid provides pressure to the body portion. This parameter differentiation enables simultaneous rapid forming of the body and precise shaping of the gate area.
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 prevents malformations and defects by maintaining the preform's temperature during the stretching process, ensuring the final-shaped container is fully formed and free of defects, with improved thermal management using thermally isolating or heat-absorbing materials.
Implementation Method 1
pressure of the liquid entering the prepared preform causing the prepared preform to expand
Implementation Method 2
a stretch rod with a deformable or heatable tip is used to isolate the gate portion from the liquid, allowing controlled expansion and heating to prevent premature cooling
Implementation Method 3
improved thermal management using thermally isolating or heat-absorbing materials
Data Source
AI summary
There is provided a system, a method and preform suitable for executing liquid forming of the preform into a final-shaped container. The present technology includes various improvements to methods, apparatuses, and systems for forming final-shaped containers from preforms using a liquid destined to be contained in the final-shaped container.