PET Bottle Trunk Deformation Control via Liquid Blow Molding
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Solution Overview
Problem
Conventional synthetic resin containers formed by air blow molding and liquid blow molding exhibit different deformation behaviors during cooling, leading to insufficient reduction of trunk deformation even with reduced pressure absorbing panels in liquid blow molding.
Innovation Solution
A synthetic resin container with a substantially circular trunk section and six reduced pressure absorbing panels arranged circumferentially, made of polyethylene terephthalate, is manufactured using liquid blow molding, where the panels are designed to deform and absorb pressure without bulging outward, and the container's density and crystal orientation are optimized to minimize deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reduced pressure absorbing panels are provided in the trunk of a container formed by liquid blow molding, then the reduced pressure generated during cooling can be absorbed, but the trunk deformation cannot be sufficiently reduced and remains non-uniform in the circumferential direction
Solution Approach 1:
The trunk is divided into multiple segments by providing a plurality of reduced pressure absorbing panels arranged at equal intervals in the circumferential direction. Each panel independently absorbs reduced pressure through deformation, ensuring uniform distribution of stress and consistent deformation behavior across the entire trunk circumference, thereby resolving the non-uniform deformation problem.
Solution Approach 2:
The reduced pressure absorbing panels are designed with specific local structural characteristics (such as predetermined deformation regions with controlled thickness or material properties) that enable them to deform in a controlled manner. This local structural optimization ensures that each panel absorbs reduced pressure uniformly, preventing non-uniform trunk deformation while maintaining overall structural integrity.
2Temperature
If the container is cooled after hot filling to room temperature, then the content liquid and air volumes decrease generating reduced pressure, but the trunk undergoes depression and deformation
Solution Approach 1:
The reduced pressure absorbing panels are pre-designed with predetermined deformation regions that are prepared in advance to absorb the reduced pressure that will be generated during cooling. These panels act as cushioning elements that anticipate and mitigate the trunk deformation caused by volume contraction of the content liquid and air during the cooling process from filling temperature to room temperature.
Solution Approach 2:
The panels are designed to change their physical state or structural parameters during cooling - specifically, they undergo controlled deformation in predetermined regions where the resin thickness or material properties are optimized. This parameter change allows the panels to absorb the reduced pressure generated during cooling without causing trunk depression or deformation.
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
The solution effectively reduces trunk deformation under reduced pressure during hot filling, ensuring uniformity and stability of the container's shape by using the described configuration and manufacturing method.
Implementation Method 1
the container used for a purpose involving hot filling is provided, in the trunk thereof, with reduced pressure absorbing panels that are configured to be deformed to absorb the reduced pressure generated within the container
Implementation Method 2
the method (which is called a liquid blow molding method) of blow molding the container by using a liquid. In a case where the content liquid is filled into the container while the container is molded according to the liquid blow molding method, the liquid heated to a predetermined temperature is supplied to a preform at a predetermined temperature
Data Source
Figure 1
AI summary
Provided is a synthetic resin container (1) that is formed in a bottle shape having a mouth (2) and a trunk (4) and that is provided in the trunk (4) with at least one reduced pressure absorbing panel (6). The trunk (4) has a density of 1.3695 g/cm3 or more, and a ratio of a crystal orientation in a transverse direction with respect to a total value of a crystal orientation in a machine direction and the crystal orientation in the transverse direction in the trunk (4) is less than 44%.