Resin Liner Neck Molding for Parting-Line-Free Pressure Sealing
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Solution Overview
Problem
Existing pressure vessels with resin liners face issues of degraded sealing properties due to parting lines and increased workload and cost in manufacturing, particularly when using blow molding processes.
Innovation Solution
A blow molding device with a blow pin featuring an annular recess portion and a ring portion that forms a smooth outer surface on the neck portion of the resin liner, preventing parting lines and enhancing sealing properties by using a self-sealing function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blow molding is used to manufacture the resin liner, then productivity is improved, but parting lines appear on the neck portion outer surface degrading sealing property
Solution Approach 1:
The invention applies local quality by creating a smooth surface treatment specifically on the sealing surface of the neck portion outer circumferential surface, while the rest of the bottle body maintains the standard blow-molded parting line structure. This localized smoothing eliminates the harmful effect of parting lines only where they contact the sealing member, preserving both productivity and sealing property.
2Reliability
If the neck portion outer surface is smoothed to eliminate parting lines, then sealing property is improved, but manufacturing workload and cost increase
Solution Approach 1:
The invention applies preliminary action by incorporating the smooth surface formation directly into the blow molding process itself, rather than adding a separate post-processing step. The blow pin with its specific surface structure creates the smooth sealing surface during the initial forming operation, eliminating the need for additional machining or finishing operations.
3Reliability
If O ring is interposed between neck portion and valve, then sealing is enhanced, but self-sealing function cannot be fulfilled and sealing property degrades
Solution Approach 1:
The invention applies self-service by designing the neck portion outer circumferential surface with inherent self-sealing properties through its smooth surface structure. This allows the sealing member to maintain effective sealing through the pressure-induced self-sealing mechanism of the resin material itself, eliminating the need for additional O rings or complex sealing structures.
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
The solution effectively prevents degradation of sealing properties and reduces manufacturing workload and cost by forming a smooth surface on the neck portion, thereby improving the self-sealing function and maintaining the integrity of the sealing member.
Implementation Method 1
a blow pin (53) configured to form the neck portion together with the molds and having an air supply opening (58) to be arranged inside the parison
Data Source
AI summary
To suppress the degradation of sealing property of a pressure vessel and the deterioration of a sealing member, and to reduce the workload and cost of manufacture, a blow molding device includes a pair of molds configured to be clamped to sandwich a parison from both lateral sides, and a blow pin configured to form a neck portion together with the molds. The blow pin includes a blow pin body portion having an outer circumferential surface of a shape corresponding to an inner circumferential surface of the neck portion, and a ring portion forming an annular recess portion between the blow pin body portion and the ring portion to form an outer circumferential surface of a tip portion of the neck portion, which is a smooth surface without any parting line.