Blow-Molded Plastic Container With Welded Bung Connectors
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Solution Overview
Problem
Plastic containers with bung fittings face issues such as material distortion and geometric deviations due to uneven cooling, leading to sealing leaks and automation failures in filling installations, particularly during high-pressure filling.
Innovation Solution
The solution involves prefabricating bung connectors with internal threads in an injection molding process and using a mirror welding process to bond them to the container, ensuring precise geometric alignment and sealing through annular welding surfaces with controlled overlap and dome-like configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bung connectors are formed directly in the blow molding process using blowing mandrels, then the container can be produced in one step, but material distortion and geometric deviations occur due to uneven cooling
Solution Approach 1:
The container production is divided into two separate processes: blow molding the container body without integrated bung connectors, and a subsequent injection molding process to add the bung connectors. This segmentation allows each component to be optimized independently, preventing the material distortion that occurs when bung connectors are formed directly in the blow molding process.
Solution Approach 2:
The container body is first blow-molded with pre-formedbung hollows positioned and sized correctly, then the bung connectors are injected into these hollows in a second process. This preliminary preparation of the container body allows the bung connectors to be formed under optimal cooling conditions separate from the main container, eliminating geometric deviations.
2Reliability
If bung connectors are formed with increased material thickness, then sealing reliability improves, but cooling time increases and material distortion occurs
Solution Approach 1:
The bung connectors are separated from the main container body and produced in a distinct injection molding process. This allows the thick-walled bung connectors to be cooled independently and more efficiently, reducing overall cooling time while maintaining the material thickness needed for reliable sealing.
Solution Approach 2:
The bung connectors are produced with optimized material thickness parameters through injection molding, allowing sufficient wall thickness for sealing reliability while controlling cooling time through process parameter optimization in the injection molding stage, separate from the container blow molding process.
3Ease of operation
If the container top is formed with convex shape and handling ring, then handling and stacking improve, but the configuration becomes considerably more difficult
Solution Approach 1:
The complex container top features (convex shape, handling ring, bung hollows) are formed in the blow molding process, while the bung connectors themselves are added in a separate injection molding process. This segmentation simplifies the blow mold design by removing the complex threaded connector geometry, reducing device complexity while preserving handling advantages.
4Productivity
If automatic filling installations are used, then filling speed increases, but precise orientation of bung connectors is required
Solution Approach 1:
The bung hollows are pre-formed in the container body during blow molding with precise positioning and orientation, and the bung connectors are subsequently injected with correct alignment. This preliminary preparation ensures that the bung connectors are precisely oriented before the container reaches the automatic filling installation, enabling high-speed automated operation without compromising orientation precision.
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 minimizes material distortion, ensures precise sealing and automation compatibility, reducing production faults and increasing efficiency in filling operations.
Implementation Method 1
The use of a solid threaded welding head with annular welding surfaces, prefabricated in an injection molding process, is bonded to the container using a mirror welding process
Data Source
AI summary
A method for creating a container is disclosed. The method can include creating a container body from a thermoplastic material via a blow molding process to thereby form a first opening extending through a top of the container body, creating a bung attachment part via an injection molding process to thereby form a second opening extending through the bung attachment part and an internally threaded surface located within the second opening, and attaching the bung attachment part to the top of the container body such that the second opening is at least partially aligned with the first opening.