Double-Wall Blow Molding Inversion Method
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Solution Overview
Problem
The production of double-wall containers, such as those used for hot coffee, is complicated due to the need for multiple parts and increased steps in the manufacturing process, particularly when attempting to mold a container with a heat-insulating double-wall structure from a single part using existing blow molding methods.
Innovation Solution
A blow molding method and apparatus that involves stretch-blowing a resin-made preform to create an intermediate molded product with bulging inner and outer walls, where the inner wall and bottom portions are pressed and inverted to form a double-wall container, simplifying the production process by maintaining residual heat to facilitate the inversion and integration of these components within the same mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double-wall container is produced by combining separately produced inner and outer containers, then the heat insulating effect is achieved, but the number of parts increases and the production process becomes complicated
Solution Approach 1:
The invention merges the production of inner and outer containers into a single blow molding process. The mold includes a cavity mold for forming the outer container and a bottom portion that forms the inner bottom, both integrated in one apparatus. The process combines stretching, blowing, and pressing operations to produce the double-wall container as a single integrated component, eliminating the need for separate production and assembly steps while maintaining the heat insulating double-wall structure
2Ease of manufacture
If an intermediate molded product is prepared in a blow molding apparatus and then pressed and inverted in another apparatus, then the double-wall container is formed, but the number of steps increases and apparatus cost increases
Solution Approach 1:
The invention combines multiple production steps (stretching, blowing, pressing, and inverting) into a single integrated blow molding apparatus. The mold includes both the cavity mold for the outer container and the bottom portion for the inner bottom, allowing all operations to be performed in one continuous process without transferring to another apparatus, thereby reducing the number of steps and apparatus cost
Solution Approach 2:
The invention performs preliminary actions within the same apparatus by maintaining residual heat of the intermediate molded product after blowing, which facilitates the subsequent pressing and inverting operations. The bottom portion is designed to press the inner bottom portion while the material is still sufficiently pliable, enabling the inversion process to occur in the same apparatus without requiring additional heating or preparation steps
3Ease of manufacture
If the inner wall portion and bottom portion are pressed and inverted in another apparatus, then the double-wall structure is achieved, but production time increases
Solution Approach 1:
The invention merges the pressing and inverting operations with the blowing operation in a single continuous process within one apparatus. The bottom portion presses the inner bottom portion during or immediately after the blowing step, and the inversion occurs continuously without interruption, eliminating the time required for transferring and repositioning the intermediate molded product in separate apparatus
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 simplifies the production process, reduces apparatus costs, and efficiently produces double-wall containers with a heat-insulating structure by integrating the inner and outer wall formation steps within the same blow molding apparatus, thereby reducing production time and complexity.
Implementation Method 1
a blowing step of stretch-blowing a resin-made bottomed preform accommodated in a mold to mold an intermediate molded product
Implementation Method 2
in a state where residual heat of the corresponding inner wall portion and the corresponding inner bottom portion is maintained such that the corresponding inner wall portion is capable of being inverted
Implementation Method 3
the double-wall container is molded by pressing the corresponding inner bottom portion such that the corresponding inner wall portion formed to bulge out from the corresponding outer wall portion is inverted
Data Source
AI summary
A blow mold method for a double-walled container, including: blowing in which an intermediate molded article is molded by stretch blowing a preform housed in a die; and pressing in which the intermediate molded article is pressed inside the die and a double-walled container is molded. During the pressing, an internal floor-corresponding section is pressed such that internal wall-corresponding section is inverted as far as the inside of an outer wall-corresponding section, in a state in which heat retention is maintained such that the internal wall-corresponding section can be inverted as far as the inside of the outer wall-corresponding section.