Thermoplastic Fuel Tank Shells with Pre-Installed Interlocking Inserts
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Solution Overview
Problem
Existing methods for producing thermoplastic hollow bodies, such as fuel tanks, face challenges in integrating complex internal components across the entire cross-section during extrusion blow molding, particularly in avoiding leaks and simplifying the assembly process for spatially complex shapes.
Innovation Solution
The method involves forming preforms into complementary shell-shaped intermediate products within a multi-part tool, allowing built-in parts to be integrated during shaping, which interlock and connect operatively when the shells are joined, enabling a spatially complex arrangement of internals without the need for extensive welding or additional equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If built-in parts are inserted later into the finished tank through assembly openings, then the installation process is simpler, but emissions increase and manual assembly work increases
Solution Approach 1:
The built-in parts are pre-installed on the inner sides of the shell halves during the molding process itself, before the shells are joined together. This preliminary action eliminates the need for separate assembly openings in the finished tank, thereby preventing emissions while maintaining installation simplicity.
2Adaptability or versatility
If built-in parts are blown around during production of the hollow body, then integration is achieved, but the arrangement is limited to specific positions
Solution Approach 1:
The molding process is segmented into two independent stages: first forming the shell halves, then separately forming and attaching the built-in parts to the inner sides. This segmentation allows built-in parts to be placed in any position on the inner surface without complicating the overall manufacturing process, as each part can be independently positioned and attached.
3Ease of manufacture
If containers are assembled from two half-shells with built-in parts, then internals can be installed in opened half-shells, but weld seams create leak points
Solution Approach 1:
Built-in parts are pre-installed on the inner sides of the shell halves during the molding process, before the shells are joined. This preliminary installation eliminates the need for separate assembly openings in the finished tank, thereby preventing emissions while maintaining installation simplicity.
4Ease of manufacture
If web-shaped or strip-shaped preforms are used to form shells, then the container can be produced in a technically simple manner, but integrating complex internals across the entire cross-section becomes difficult
Solution Approach 1:
The molding process is segmented into two independent stages: first forming the shell halves, then separately forming and attaching the built-in parts to the inner sides. This segmentation allows built-in parts to be placed in any position on the inner surface without complicating the overall manufacturing process, as each part can be independently positioned and attached.
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 simplifies the integration of internal components like struts and fluid lines across the entire cross-section, reduces manual assembly complexity, and minimizes leak points by allowing components to engage and connect seamlessly during the forming process, enhancing the production efficiency and integrity of thermoplastic containers.
Implementation Method 1
The preform is expanded by applying gas pressure within the closed blow mold.
Data Source
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AI summary
The invention relates to a method for producing hollow bodies (12) from thermoplastic plastic, in particular to a method for producing plastic fuel tanks. According to said method, web- or strip-type preforms (8) consisting of plasticised material are shaped in a multi-part (2a, 2b, 3) mould that forms a mould cavity, by the expansion of the preform and the application of the latter to the inner contours of the mould cavity. Two complementary intermediate products in the form of shells (10a, 10b) are formed in a first step. Inserts (7) are then fixed to the inner faces of the shells that lie opposite one another when installed. At least some of the inserts of complementary shells are complementary with respect to one another, in such a way that they can be interconnected to form a composite component or a functional unit. The shells are joined in such a way that the complementary inserts engage with one another and/or are operatively interconnected.