Mold Apparatus for Wrinkle-Free Thick Bottom Preforms
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Solution Overview
Problem
The existing injection molding methods for forming preforms with thickened bottoms often result in wrinkles on the surface, which persist after blow molding, making it difficult to achieve an aesthetic appearance comparable to glass containers.
Innovation Solution
A mold apparatus comprising a neck mold, an injection cavity mold, and an injection core mold, where the inside core mold is movable and regulated by an urging member to adjust its position based on pressure changes within the injection space, allowing for controlled injection and solidification of the resin material to prevent wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a wide spacing between the injection cavity mold and the injection core mold is set to form a thick-walled bottom, then the bottom wall thickness is increased, but wrinkles form on the surface of the bottom
Solution Approach 1:
The inside core mold is made movable rather than fixed, allowing it to slide in the axial direction in response to pressure changes during injection molding. This dynamic adjustment enables the mold to adapt to the injection process, preventing wrinkle formation while maintaining thick bottom walls
Solution Approach 2:
The invention changes the pressure parameter response by allowing the inside core mold to move in accordance with pressure variations within the injection space. This parameter-based control mechanism prevents surface defects while achieving the desired wall thickness
2Manufacturing precision
If the inside core mold is made movable to prevent wrinkles, then surface quality is improved, but the device complexity increases
Solution Approach 1:
The inside core mold serves itself by automatically moving in response to pressure changes within the injection space. The mold structure utilizes the injection pressure itself to drive the movement, eliminating the need for external actuators or complex control systems
Solution Approach 2:
The outside core mold acts as an intermediary that holds and guides the inside core mold, providing a simple mechanical constraint system that enables controlled movement without requiring complex actuation mechanisms
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 method enables the formation of preforms with thicker bottoms without surface wrinkles, reducing manufacturing time and costs while maintaining a high aesthetic quality, even at higher injection speeds.
Implementation Method 1
holding the inside core mold slidably in accordance with a change in a pressure within an injection space
Implementation Method 2
regulation means for regulating movement of the inside core mold toward an outside of the injection cavity mold
Implementation Method 3
injection molding a bottomed tubular preform having a neck with an opening portion at an upper end thereof, a body continuous with the neck, and a bottom continuous with the body
Data Source
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AI summary
A mold apparatus, an injection molding apparatus, and an injection molding method, which can satisfactorily form a preform having a bottom thicker than a body, are provided. The mold apparatus (30) comprises a neck mold (32), an injection cavity mold (33), and an injection core mold (34) having an inside core mold (37) and an outside core mold (38), and further comprises a regulation means, such as an urging member (41), for regulating the movement of the inside core mold (37) toward the outside of the injection cavity mold (33).