Double-Wall Container Crease Structure for Stronger Opening Edges
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Solution Overview
Problem
Existing double-wall resin containers manufactured by folding an inner wall forming part toward an outer wall forming part face issues with insufficient strength at the opening edge, deformation when lifted with contents, and difficulty in shaping the opening edge accurately, especially when a lid member is mounted.
Innovation Solution
A method involving blow molding, inverting, and collapsing processes to form a crease at the boundary portion between inner and outer wall parts, using an inversion device with temperature-controlled molds to create a collapsed portion and reinforcing structures for enhanced strength and shape accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inner wall forming part is inverted and folded toward the inner side of the outer wall forming part to form a double-wall container, then the manufacturing process is simplified and manufacturing efficiency is improved, but sufficient strength cannot be ensured at the opening edge and the container deforms when lifted with contents
Solution Approach 1:
The invention applies preliminary action by forming a projection part at the boundary portion between the inner wall forming part and outer wall forming part before the inverting process. This projection part serves as a pre-positioned reinforcing structure that will become the collapsed portion after inverting, providing strength at the opening edge before the actual folding occurs
Solution Approach 2:
The invention applies local quality by creating a collapsed portion specifically at the boundary portion (opening edge) through the projection part structure, while the rest of the container walls maintain their original double-wall configuration. This localized reinforcement at the critical opening edge area provides strength where needed without compromising the overall manufacturing efficiency
2Productivity
If the inner wall forming part is inverted and folded toward the inner side of the outer wall forming part, then the manufacturing process is simplified, but the opening edge shape accuracy deteriorates and becomes difficult to shape accurately
Solution Approach 1:
The projection part is formed in advance during the blow molding process to define the precise geometry of the collapsed portion. This preliminary structuring ensures that when the inverting and collapsing occur, the opening edge achieves accurate shaping with a flat top surface, rather than an undulating shape
Solution Approach 2:
The invention utilizes controlled curvature and folding geometry in the collapsed portion to achieve accurate shaping. The projection part's specific geometric configuration ensures that when collapsed, it forms a precise flat top surface at the opening edge, transforming the folding process into a precision shaping operation
3Adaptability or versatility
If a groove portion is provided in the container to mount a lid member, then the container can be closed, but the strength at the opening edge becomes further insufficient
Solution Approach 1:
The invention segments the boundary portion structure by providing both the groove portion for lid mounting and the projection part for reinforcement as distinct but integrated features. The projection part is positioned at the boundary portion while the groove portion is provided in the container wall, allowing both functions to coexist without compromising strength
Solution Approach 2:
The invention applies local quality by concentrating the reinforcement function at the boundary portion through the projection part, while the groove portion for lid mounting is provided in the container wall. This localized reinforcement strategy ensures that the critical opening edge maintains sufficient strength even with the groove portion present
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 simplifies manufacturing, improves strength at the opening edge, and ensures accurate shaping, preventing deformation even when containing beverages and allowing secure mounting of a lid member.
Implementation Method 1
a blow molding process of forming an intermediate molded body by blow molding
Implementation Method 2
an inverting process of pushing the inner wall forming part inside the outer wall forming part and inverting the inner wall forming part
Implementation Method 3
a collapsing process of collapsing the projection part in a depth direction of the intermediate molded body to form a crease at the boundary portion between the inner wall forming part and the outer wall forming part
Data Source
AI summary
A method for manufacturing a double-wall container includes a blow molding process of forming an intermediate molded body by blow molding, the intermediate molded body including a projection part that is provided at a boundary portion between an inner wall forming part and an outer wall forming part and projects outward in a radial direction of the outer wall forming part; an inverting process of pushing the inner wall forming part inside the outer wall forming part and inverting the inner wall forming part, thereby forming the intermediate molded body into the double-wall container; and a collapsing process of collapsing the projection part in a depth direction of the intermediate molded body to form a crease at the boundary portion between the inner wall forming part and the outer wall forming part, the collapsing process being performed before the inverting process.