Two-Step Blow Molding Unit for PET Bottle Heat Resistance
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Solution Overview
Problem
Current blow molding methods for PET bottles face challenges in achieving both high heat resistance and energy efficiency, with the 2-stage method providing high heat resistance but low energy efficiency due to the need for reheating preforms, and the 1-stage method offering better energy efficiency but insufficient heat resistance.
Innovation Solution
A mold unit and blow molding apparatus that includes a first mold part for heat-set blowing at a high temperature and a second mold part for blow molding at a lower temperature, allowing for sequential processing without the need for intermediate temperature adjustments, thereby improving both energy efficiency and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the 2-stage method is adopted with offline connection between injection molding apparatus and blow molding apparatus, then heat resistance of PET bottle is improved, but energy efficiency deteriorates due to natural cooling and reheating of preform
Solution Approach 1:
The patent combines the injection molding apparatus and blow molding apparatus into an integrated online system, eliminating the offline storage and natural cooling step. The preform is directly transferred from injection molding to blow molding without leaving the system, thereby maintaining heat and eliminating the need for reheating, which resolves the contradiction between heat resistance and energy efficiency.
Solution Approach 2:
The patent establishes a continuous production process where the preform moves directly from injection molding to blow molding without interruption or cooling. This continuous action maintains the thermal state of the preform, allowing heat resistance to be achieved without energy-intensive reheating, thus resolving the energy efficiency contradiction.
2Use of energy by moving object
If the 1-stage method is adopted, then energy efficiency is improved by avoiding natural cooling, but heat resistance of PET bottle deteriorates
Solution Approach 1:
The patent segments the blow molding process into two distinct stages: heat-set blowing at high temperature for achieving heat resistance, and final blowing at lower temperature for shaping. This segmentation allows each stage to be optimized independently, maintaining energy efficiency by avoiding cooling while ensuring heat resistance through controlled high-temperature processing.
Solution Approach 2:
The patent changes the temperature parameter dynamically during the blow molding process. The first blow is performed at high temperature (80-120°C) to achieve heat resistance, then the temperature is reduced for the second blow to achieve final shaping. This parameter change enables simultaneous achievement of energy efficiency and heat resistance.
3Temperature
If separate heating part and blow molding part are used, then heat resistance is improved, but equipment complexity and size increase
Solution Approach 1:
The patent designs the blow molding apparatus to perform multiple functions: it serves as both the heating part and the blow molding part. The same mold and apparatus structure accomplish both heat-set blowing and final blowing, eliminating the need for separate heating equipment and reducing overall system complexity while maintaining heat resistance.
Solution Approach 2:
The patent merges the heating function and blow molding function into a single integrated apparatus. The mold structure incorporates heating elements and performs both heat-set blowing and final blowing operations, thereby reducing equipment complexity and size while achieving the required heat resistance.
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 configuration enables the production of PET bottles with sufficient heat resistance while enhancing energy efficiency by eliminating the need for reheating preforms and reducing equipment size and costs.
Implementation Method 1
it is possible to set the first temperature, which is to be used in the heat-set blowing of the first step, to a temperature higher than the second temperature, which is to be used in the second step, for example, to a temperature at which crystallization of resin is promoted
Implementation Method 2
a first mold part for performing a first step of subjecting a preform to heat-set blowing at a first temperature, and a second mold part for performing a second step of blow molding an intermediate molded article
Data Source
AI summary
One purpose of the present invention is to provide a mold unit which is capable of achieving improvements in both energy efficiency and heat resistance performance; a blow molding apparatus; and a blow molding method. The present invention is provided with: a first mold part for performing a first step in which a preform is subjected to heat-set blowing at a first temperature; and a second metal mold part for performing a second step in which an intermediate molded body blow molded as a result of the heat-set blowing is blow molded at a second temperature lower than the first temperature, to produce a container. The first mold part and the second mold part are disposed adjacently to each other.