Hollow Body Insert Fixation via Differential Pressure Molding
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Solution Overview
Problem
Existing methods for manufacturing hollow bodies, such as fuel tanks, face challenges in ensuring a good fixation and tight welding of inserts while avoiding damage or collapse, particularly due to differential pressures during molding processes.
Innovation Solution
A method involving molding a preform into shells, joining an insert to the inner surface, and applying a controlled pressure difference between the main and sub volumes to achieve adherence and prevent damage, with pressures ranging from 0.20 to 3.00 bar, optimized based on insert type and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high pressure is applied during molding to ensure good fixation and tight welding of insert to inner wall, then welding quality is improved, but insert may collapse or be damaged
Solution Approach 1:
The patent applies different pressures to different regions: a first pressure to the main volume and a second (lower) pressure to the sub volume enclosed by the insert. This local pressure differentiation allows the insert region to be protected from excessive pressure that would cause collapse, while still achieving adequate welding quality at the insert-to-wall interface through controlled pressure application during the molding process
Solution Approach 2:
The patent dynamically adjusts pressure conditions during the molding process by applying different pressures at different stages and regions. The pressure application is optimized based on the specific moment in the molding cycle and the specific region being formed, allowing adaptation between the need for strong welding and the need to protect the insert from damage
2Stability of the object's composition
If differential pressure is applied to ensure insert fixation, then welding adherence is improved, but insert collapse risk increases
Solution Approach 1:
The patent implements local quality control by applying a first pressure to the main volume and a second, lower pressure to the sub volume enclosed by the insert. This localized pressure management ensures that the insert maintains its structural integrity while still achieving stable fixation to the inner wall through the controlled pressure differential in the surrounding main volume
3Reliability
If high pressure is used to ensure tight welding, then sealing effectiveness is improved, but insert damage occurs
Solution Approach 1:
The patent applies local quality control by differentiating pressure between the main volume and the sub volume enclosed by the insert. The lower pressure in the sub volume protects the insert from damage while the pressure control in the main volume ensures adequate sealing effectiveness at the insert-to-wall interface, achieving reliable sealing without compromising insert integrity
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 ensures a secure fixation and tight welding of inserts within hollow bodies, preventing damage and collapse, while maintaining structural integrity and sealing effectiveness.
Implementation Method 1
Another known technique for manufacturing hollow bodies is Twin Sheet Thermoforming
Implementation Method 2
PCT application with publication number WO 2010/006900 in the name of the applicant discloses a process for manufacturing a plastic fuel tank by molding a parison using a mold comprising two cavities and a core
Implementation Method 3
The main and sub pressure are chosen such that a pressure difference between the main volume and the sub volume is bigger than 0.20 bar (P1'-P2'>0.20 bar) and smaller than 3.00 bar
Implementation Method 4
ensuring a good fixation, an in particular a tight welding, of an insert to an inner wall of a hollow body
Data Source
AI summary
A method for manufacturing a hollow body, typically a tank, from a plastic material. The method includes molding a preform into shells in a molding tool; joining an insert to an inner surface of a shell of said shells, the insert defining a sub volume within the hollow body to be made; joining together the shells to form the hollow body by closing the molding tool and applying a main pressure to a main volume enclosed by the shells. It is proposed to apply a sub pressure to the sub volume while applying the main pressure to the main volume, such that a pressure difference between the main volume and the sub volume is bigger than 0.20 bar (P1′−P2′>0.20 bar) and smaller than 3.00 bar (P1′−P2′<3.00 bar).