Blow Molding Device Suckback Mechanism Headspace Control
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Solution Overview
Problem
The existing blow molding methods using pressurized liquids face challenges in accurately adjusting the headspace of containers, leading to variations that affect the merchantability of products like beverages and cosmetics, as the liquid used for molding can scatter during the process, making it difficult to maintain a constant headspace.
Innovation Solution
A blow molding device and method that utilize a suckback mechanism to draw back the liquid inside the container, followed by the introduction of a gas to restore the volume, allowing precise adjustment of the headspace by controlling the volume reduction deformation caused by the suckback process, using a plunger pump with a servo mechanism for precise control and a valve mechanism to manage the gas introduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pressurized liquid is used for blow molding to eliminate the filling process, then productivity is improved, but the liquid scatters from the mouth tube portion to the peripheral outside when disengaging the blow nozzle, making it difficult to adjust the headspace to a constant value
Solution Approach 1:
The blow nozzle is designed with a liquid retaining structure (liquid retaining portion) that preliminarily captures and holds the liquid after the molding process. This preliminary action prevents the liquid from scattering outside the mouth tube portion, enabling subsequent precise control of the headspace volume through the retained liquid amount.
2Ease of manufacture
If the liquid is used as pressurized fluid for blow molding, then the filling process is simplified, but the headspace varies depending on the product, leading to problems in merchantability
Solution Approach 1:
The system incorporates a feedback mechanism where the liquid retaining structure captures the liquid that would otherwise scatter, and the headspace is adjusted based on the retained liquid amount. This feedback loop ensures that the headspace remains consistent across different products, maintaining reliability and merchantability while preserving the ease of manufacture benefit.
3Manufacturing precision
If a suckback mechanism is introduced to draw back the liquid, then headspace adjustment precision is improved, but the device complexity increases
Solution Approach 1:
The liquid retaining structure is merged with the blow nozzle assembly, integrating the headspace adjustment function into the existing molding device. By combining the liquid retention and headspace adjustment functions in a unified structure, the device complexity is minimized while achieving precise headspace control through the suckback mechanism.
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
Enables high-precision and productive adjustment of the headspace within the container, ensuring consistent product quality and merchantability by accurately restoring the container's original shape and volume, even after volume reduction deformation.
Implementation Method 1
drawing back the liquid inside the container to a pressurized liquid feeding unit side by means of a suckback mechanism
Implementation Method 2
introducing a gas into the container so as to restore, to its original shape, the volume reduction deformation of the container
Implementation Method 3
feeding a liquid into the preform from a pressurized liquid feeding unit through the blow nozzle
Data Source
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AI summary
Provided is a method for manufacturing a synthetic resin container, comprising: after the shaping of a container (41), drawing back a liquid (L) inside the container (41) to a pressurized liquid feeding unit (21) side by means of a suckback mechanism (SB) disposed at a predetermined position in a feeding channel (F) of the liquid (L) from the pressurized liquid feeding unit (21) to a mouth tube portion (32) of a preform (31); closing the feeding channel (F) by means of a valve mechanism (Vm) disposed on the downstream side of the suckback mechanism; introducing a gas into the container (41) so that the volume reduction deformation of the container (41) resulting from the drawing back of the liquid (L) is restored to its original shape; and adjusting a headspace (HS) inside the container (41) with the amount of volume change associated with the volume reduction deformation.