Continuous Blow Molding Device 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 energy efficiency and sufficient heat resistance, with the 2-stage method being energy-inefficient due to natural cooling and reheating, and the 1-stage method lacking sufficient heat resistance.
Innovation Solution
A blow molding device and method that includes an injection molding unit, a blow molding unit with separate molds for heat-set blowing and final blowing, and a conveyance system allowing continuous processing without cooling, enabling higher heat-set temperatures for improved heat resistance and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the 2-stage method is used to manufacture PET bottles with high heat resistance, then heat resistance is improved, but energy efficiency deteriorates due to natural cooling and reheating
Solution Approach 1:
The patent implements continuous blow molding where the blowing process proceeds uninterrupted from the first mold to the second mold without cooling the preform in between. The preform is continuously conveyed through the heating zone and into the second mold, maintaining thermal energy and eliminating the energy-wasting cool-down and reheat cycle of the 2-stage method.
Solution Approach 2:
The patent combines the heat-set blowing and final blowing operations into a single continuous process within one blow molding device. Both molds are positioned along the conveyance path, allowing the preform to undergo sequential molding operations without leaving the heated state, thereby merging what were traditionally separate thermal processing stages.
2Use of energy by moving object
If the 1-stage method is used to improve energy efficiency, then energy efficiency is improved, but heat resistance deteriorates due to insufficient crystallization
Solution Approach 1:
The patent divides the single blowing operation into two sequential stages occurring in different molds: first mold performs heat-set blowing at higher temperature to promote crystallization, second mold performs final shaping at lower temperature. This segmentation allows each stage to be optimized for its specific function while maintaining continuous thermal processing.
Solution Approach 2:
The patent changes the temperature parameter between molding stages by using a heating part that maintains high temperature for the first mold (promoting crystallization) and allows cooling for the second mold (final shaping). This parameter variation enables sufficient heat resistance development while maintaining continuous operation and energy efficiency.
3Reliability
If separate first mold and second mold are provided for sequential processing, then heat resistance is improved through independent temperature control, but device complexity increases
Solution Approach 1:
The conveyance unit serves multiple functions: it transports the preform from injection molding to the first mold, conveys the intermediate product to the second mold, and maintains thermal conditions throughout the process. This multi-functional design reduces the need for separate handling systems and minimizes overall device complexity despite having multiple molds.
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 enhances energy efficiency by eliminating the need for reheating and achieves sufficient heat resistance by promoting resin crystallization, while reducing residual stress and maintaining production quantity.
Implementation Method 1
subjecting the preform to heat treatment blowing at a first temperature... 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... to a temperature at which crystallization of resin is promoted
Implementation Method 2
heat the same to a temperature suitable for blowing in a heating part
Data Source
AI summary
A blow molding device includes: a base; an injection molding unit manufacturing a bottomed preform made of resin; a blow molding unit; a support part supporting the preform; and a conveying unit conveying the support part to the blow molding unit. The blow molding unit includes: a blow mold; a movement unit capable of moving the blow mold relative to the support part; one mold opening and closing mechanism; and a pair of mold opening and closing plates connected to the mold opening and closing mechanism. The moving unit is configured to move the blow mold in a non-coupling state to a position between the pair of mold opening and closing plates, the blow mold in the non-coupling state being not coupled to the pair of mold opening and closing plates and not located between the pair of mold opening and closing plates.