Preform Air Evacuation via Steam Injection in Hydraulic Container Forming
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Solution Overview
Problem
In hydraulic forming of plastic containers, the rapid high-pressure process makes it difficult to control air evacuation from preforms, leading to issues like changes in dissolved gas composition, foaming, and reduced shelf life, especially at high speeds where traditional venting methods are inefficient.
Innovation Solution
A method involving the injection of a gaseous product, such as steam, into the preform before forming, where the injection conditions are optimized to expel at least 90% of the air, with the gaseous product being absorbed by the forming liquid, ensuring minimal air remains when the forming step begins, and the steam is injected in a direction parallel and radially offset to the preform's axis to enhance air removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional venting methods are used during hydraulic forming, then air can be evacuated from the preform, but at high speeds the venting time is insufficient and product is lost
Solution Approach 1:
The patent applies preliminary action by injecting a gaseous product into the preform before the hydraulic forming step to pre-expel air from the preform. This preliminary air removal ensures that when high-speed forming occurs, there is minimal air to cause problems, thus maintaining both high productivity and reliability without requiring extended venting time during the forming process itself.
2Productivity
If high liquid pressure is used in hydraulic forming, then forming speed and container quality are improved, but air dissolves in the filled product causing foaming and reduced shelf life
Solution Approach 1:
The patent uses preliminary action by injecting a gaseous product before forming to expel air from the preform in advance. This ensures that when high liquid pressure is applied during forming, there is minimal air present to dissolve in the filled product, thereby preventing foaming and shelf life reduction while maintaining high forming speed and container quality.
3Reliability
If steam is injected for sterilization before forming, then product sterility is improved, but the heat profile of the preform may be affected
Solution Approach 1:
The patent applies universality by using a gaseous product that serves multiple functions simultaneously: it expels air from the preform and provides sterilization. This multi-functional approach eliminates the need for separate sterilization heating, thereby maintaining product sterility while avoiding adverse effects on the preform's heat profile that would occur with traditional pre-form sterilization methods.
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 effectively removes air from the preform, preventing re-entry and maintaining product quality, while allowing for high-speed forming without significant impact on sterility or heat profile, ensuring improved shelf life and operational efficiency.
Implementation Method 1
a gaseous product is injected into the preform containing air, the injection conditions being determined such that the injected gaseous product expels air from the preform
Implementation Method 2
said gaseous product being absorbable by said forming liquid
Data Source
AI summary
A method for manufacturing plastic containers in which, for each container, a plastic preform containing air is supplied; the preform is heated at a preform temperature over the glass temperature of the preform material, the preform is inserted in a mold having a mold cavity; and the preform is expanded to a container having the shape of a mold cavity by a forming liquid. The method also includes, between steps (b) and (d), the injecting of a gaseous product into the preform containing air, wherein the gaseous product is absorbable by the forming liquid. The injection conditions of the gaseous product are selected such that the injected gaseous product expels the air out of the preform.