Container Manufacturing with Die-Formed Inner-Surface Unevenness

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Solution Overview

Problem

Conventional direct blow molding technologies cannot produce containers with continuous unevenness on the inner surface or different thicknesses in the peripheral direction, limiting design flexibility and functionality.

Innovation Solution

A method and apparatus that form a parison with unevenness on the outer surface by using a die with a specific opening shape, allowing the parison to be expanded to create a container with alternating concave and convex portions on the inner surface, and adjustable thicknesses through controlled movement of the core and die.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a groove is formed in a core to create thickness variation in the peripheral direction, then containers with different thicknesses can be molded, but containers with continuous unevenness on the inner surface cannot be manufactured

Engineering Contradiction:

Improvethickness variation controlVSAvoidinner surface unevenness design

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

Instead of forming unevenness on the inner surface of the die (which would create outer surface unevenness), the invention forms unevenness on the outer surface of the die. This inverted approach creates corresponding unevenness on the inner surface of the extruded parison, which then transfers to the inner surface of the final container when expanded. This resolves the contradiction by achieving inner surface unevenness while maintaining precise thickness control.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The unevenness is pre-formed on the outer surface of the die before the extrusion process begins. This preliminary shaping of the die surface ensures that the parison acquires the desired thickness variation pattern during extrusion, enabling subsequent formation of containers with continuous inner surface unevenness without requiring complex post-processing or specialized core configurations.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If the die opening has a shape with unevenness on the outer periphery to form parison unevenness, then continuous unevenness can be achieved on the inner surface, but the manufacturing complexity increases

Engineering Contradiction:

Improvecontinuous unevenness formationVSAvoiddie opening shape complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The die opening is designed with localized unevenness features (convex and concave portions) distributed around its periphery. Each local region of the die opening has a specific shape that corresponds to the desired thickness variation at that position. This local quality approach allows continuous unevenness to be formed throughout the parison circumference while keeping the overall die structure relatively simple and manufacturable.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If unevenness is formed on the outer surface side of the container by shaping the container mold, then it can be easily formed, but containers with unevenness on the inner surface side or different thicknesses cannot be formed

Engineering Contradiction:

Improveouter surface unevenness formationVSAvoidinner surface thickness control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention inverts the conventional approach by forming unevenness on the outer surface of the die rather than the inner surface of the container mold. This causes the parison to be extruded with corresponding unevenness on its outer surface, which then transfers to the inner surface of the final container. This resolves the contradiction by achieving inner surface unevenness and thickness control through a method that is as easy to manufacture as conventional outer surface forming.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Enables the production of containers with continuous unevenness and varying thicknesses on the inner surface, enhancing design possibilities and functionality, such as improved appearance and ease of labeling.

Implementation Method 1

a parison forming die that extrudes a thermoplastic resin in a molten state into a tube shape to form a parison

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 2

a container mold that sandwiches the parison in a state where one end portion of the formed parison is sealed and expands it from the inner side to form a container shape

Methodology Applied

Scientific EffectGas pressure expansion: Pressure Increase

Data Source

PatentEP4644088A1Method for manufacturing container, apparatus for manufacturing container, and container

Publication Date: 2025.11.05 GIVER LIFE CO LTD

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AI summary

A container having unevenness on an inner surface is manufactured. A container manufacturing method includes step A of forming a tube-shaped parison having unevenness on an outer surface, a step B of sandwiching the parison with a mold, and a step C of expanding the parison from an inner side to form a container, in which in the step A, a parison having unevenness on the outer surface is formed by extruding a resin from a die, in which an opening portion of the die from which the resin is extruded has a shape with unevenness on an outer periphery, and unevenness are formed on an inner surface of the formed container.