Flat Resin Container Blow Molding for Uniform Wall Thickness
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Solution Overview
Problem
Existing methods for manufacturing flat resin containers with non-circular cross-sections, such as elliptical or rectangular shapes, often result in uneven thickness and appearance defects due to varying stretching ratios, and require complex control during blow molding, making it difficult to stabilize the shape and appearance of the container.
Innovation Solution
A method and apparatus that includes a temperature adjustment unit to equalize and adjust the temperature of preforms before blow molding, followed by biaxial stretching to ensure uniform thickness and shape consistency, using a hot-parison type blow-molding apparatus with specific mold configurations to stabilize the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If biaxial stretching blow molding is used to manufacture flat containers with non-circular cross-sections, then aesthetic appearance and dimensional accuracy are improved, but manufacturing complexity and process control difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-blowing the preform in parallel with the mold clamping step. This preliminary blow creates an intermediate shaped body that is then formed into the final flat container shape. By performing this preparatory shaping action before the main molding process, the patent simplifies the overall process control while achieving the desired dimensional accuracy and aesthetic appearance of flat containers with non-circular cross-sections.
2Ease of manufacture
If extrusion blow molding method is used, then manufacturing simplicity is maintained, but aesthetic appearance and dimensional accuracy deteriorate
Solution Approach 1:
The patent segments the manufacturing process into two distinct stages: extrusion blow molding to create a preliminary shaped body, followed by a second forming stage to achieve the final flat container shape with non-circular cross-section. This segmentation allows the first stage to maintain manufacturing simplicity while the second stage achieves the required aesthetic appearance and dimensional accuracy, effectively resolving the contradiction between ease of manufacture and manufacturing precision.
3Manufacturing precision
If post-process cutting and trimming are applied to extrusion blow molded containers, then shape accuracy is improved, but production time and material waste increase
Solution Approach 1:
The patent performs the shaping action preliminarily during the extrusion blow molding stage itself, creating a preliminary shaped body that is already close to the final geometry. This eliminates the need for subsequent cutting and trimming operations to achieve shape accuracy, thereby reducing production time and minimizing material waste while maintaining the required manufacturing precision.
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 method enables the stable production of flat containers with improved appearance by uniformly stretching and cooling the preform, reducing uneven thickness and enhancing shape stability, thereby eliminating elongated thick portions and improving aesthetic quality.
Implementation Method 1
a temperature adjustment unit to equalize and adjust a temperature of the preform
Implementation Method 2
performing cooling blow for cooling the intermediate molded body after the preliminary blow to adjust a temperature
Implementation Method 3
a blow molding unit to bring the temperature-adjusted intermediate molded body into contact with a second mold
Data Source
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AI summary
A method of manufacturing a resin container having a flat cross-sectional shape includes a temperature adjusting step of preliminarily blowing a resin preform in a first mold to mold an intermediate molded body having a diameter larger than a diameter of a container short diameter side and adjusting a temperature of the intermediate molded body in the first mold, and a blow molding step of bringing the temperature-adjusted intermediate molded body into contact with a second mold to compress the intermediate molded body in a container short diameter direction, and then stretching and blow molding the intermediate molded body in the second mold to manufacture the resin container.