Plastic Container Edge Gating for Warping Prevention
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Solution Overview
Problem
Existing methods for producing plastic containers via injection molding often result in hot-spot areas on the side surfaces, leading to warping, sinking, and poor surface quality, which hinders sticker attachment, printing, and visual appearance.
Innovation Solution
The method involves injecting plastic material onto the edges or in the vicinity of the edges of the container, rather than centrally on the side surfaces, using a gating system that positions injection points at the beginning of the radius end of rounded container edges or along container edges, thereby avoiding hot-spot issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gating takes place centrally on the side surfaces of the plastic container, then the container can be efficiently produced by injection molding, but hot-spot areas occur causing warping, sinking, and poor surface quality
Solution Approach 1:
The patent transitions the gating location from the two-dimensional surface center to the three-dimensional edge region of the container. By positioning gating points at the edges where side walls meet the base or other side walls, the injection process utilizes the edge geometry to distribute material flow more evenly, avoiding the hot-spot problems associated with central surface gating while maintaining production efficiency.
2Productivity
If injection points are located on the side surfaces, then material can be injected efficiently, but the injection points create visible bumps that prevent sticker attachment and printing
Solution Approach 1:
The patent extracts the gating function from the visible side surfaces and relocates it to the edge regions. By positioning gating points where side walls adjoin other side walls or the base, the injection points are effectively removed from the visible surface area, eliminating the bumps that would interfere with labeling and printing operations.
3Weight of moving object
If wall thicknesses are reduced to meet design requirements, then the container becomes lighter and more efficient, but the pressure requirement in the injection mold increases
Solution Approach 1:
The patent utilizes the edge dimension for gating, allowing material to flow into thin-walled sections from a strategic location rather than forcing material through long path lengths from central surface gating. This edge-based gating reduces the effective flow path length and pressure requirements, enabling successful injection molding of containers with reduced wall thicknesses.
Data Source
AI summary
The method involves molding a rounded container edge (14) of a plastic container (10) by an injection molding process through two molding points (30), where the plastic container comprises a container bottom (12) and a container wall with two container wall segments (13) that are joined together and form the edge in a joining region. A surface of the bottom is centrally molded, and the plastic container is manufactured by an injection molding device (20) using a sequential injection molding process, where the molding device comprises a tool (21) with a contour of the plastic container. An independent claim is also included for a plastic container.