Hollow Article Molding with Integrated Heating and Bonding
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Solution Overview
Problem
Existing methods for manufacturing hollow molded articles face challenges such as complex injection processes, weak joint strength, and the need for additional equipment like pressing members or heaters, which can lead to precision issues and increased costs.
Innovation Solution
A method involving primary molding of semi-finished articles with joint faces using a fixed and movable die, followed by secondary molding where a heating module with surfaces similar to the joint faces is used to melt and then retract, allowing contact bonding within the same molding device without the need for external pressing members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary injection molding is used to join semi-finished hollow articles, then the hollow product can be completely sealed and have uniform thickness, but the injecting machine structure becomes long or molding time increases, and the molding device structure becomes complex
Solution Approach 1:
The patent combines the primary molding and secondary joining operations into a single integrated molding device. The movable die serves dual purposes: first for primary molding of semi-finished articles, then for secondary molding to join them. This eliminates the need for separate injecting machines and complex transfer mechanisms, reducing overall device complexity while maintaining sealing quality through continuous operation within the same device.
Solution Approach 2:
The molding device is designed with multi-functionality, where the same fixed die and movable die are used for both primary molding and secondary joining operations. The movable die can perform both initial cavity closure and subsequent joining by superposing semi-finished articles, eliminating the need for specialized equipment and reducing structural complexity.
2Strength
If secondary injection pressure is increased to improve joining force, then the joining strength increases, but molten resin may leak from the joint space to the interior of the hollow product
Solution Approach 1:
The patent applies preliminary action by first superposing the semi-finished hollow articles with their joint surfaces aligned before applying injection pressure. The articles are positioned and held in place with the joint spaces properly aligned, ensuring that when molten resin is injected, it fills the joint space uniformly without leaking into the hollow interior. This preliminary positioning prevents resin leakage while achieving strong joining.
3Device complexity
If the molding device structure is simplified to reduce complexity, then manufacturing cost decreases, but the ability to maintain precision and uniformity in joining may be compromised
Solution Approach 1:
The patent employs self-service mechanisms where the molding device uses its own structural elements for both molding and joining operations. The fixed die and movable die, already present for primary molding, are utilized for secondary joining without requiring additional specialized components. The device's inherent clamping and positioning capabilities ensure precise alignment and uniform joining, maintaining manufacturing precision while simplifying the overall structure.
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 results in hollow molded articles with strong, uniformly bonded joints, high precision, and reduced manufacturing complexity and cost, while avoiding the limitations of external heating and pressing, ensuring accurate bonding before the articles solidify.
Implementation Method 1
a heating module having heating surfaces similar to the joint faces is inserted between the joint faces, and the joint faces are melted
Implementation Method 2
the joint faces are melted and contact bonded in the secondary molding
Implementation Method 3
the joint faces are melted and contact bonded by the closing of the same molding device or by pressing the semi-finished molded articles inside the molding device
Data Source
AI summary
First and second semi-finished molded articles and a third semi-finished molded article are molded simultaneously so as to have joint end faces by using a slide die, a fixed die, and first and second slide cores fitted to the fixed die. The slide die with the third semi-finished molded article remaining thereon is moved toward the first and second slide cores, and their respective joint end faces are registered. Heating surfaces are inserted between the joint end faces. After melting the joint end faces, the heating surfaces are retracted, and the molding device is closed to weld the joint end faces.