Spiral Ridges on Container Inner Surface
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Solution Overview
Problem
Conventional direct blow molding machines are unable to form spiral ridges on the inner surface of containers without the shape collapsing due to the parison's weight, as the ridges stretch in the axial direction during extrusion.
Innovation Solution
A process involving the extrusion of a tubular parison with raised ridges, followed by twisting the parison while it is still hanging from the die, and then inflating it to form spiral ridges on the inner surface, which prevents shape collapse and allows for the creation of desired spiral ridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional direct blow molding is used to form raised ridges on the inner surface of containers, then linear ridges extending along the axial direction can be formed, but spiral ridges cannot be formed without shape collapse due to parison weight
Solution Approach 1:
The invention applies preliminary cooling to the parison immediately after extrusion, before the spiral ridges are formed. By cooling the parison while it is still hanging from the die, the resin becomes sufficiently rigid to maintain the spiral ridge shape during the subsequent twisting and molding operations, preventing shape collapse that would otherwise occur due to the parison's weight
Solution Approach 2:
The invention introduces a dynamic twisting motion to the parison during the molding process. The parison is rotated around its axial direction while being inflated in the mold, transforming the raised ridges into spiral ridges. This dynamic approach allows the formation of complex spiral geometries that cannot be achieved with static conventional molding methods
2Adaptability or versatility
If the parison is extruded with raised ridges and then inflated to form spiral ridges, then spiral ridge formation is achieved, but the process complexity increases
Solution Approach 1:
The invention merges multiple operations into a integrated sequence: the parison is extruded with raised ridges, cooled in place while hanging from the die, then twisted and inflated within the same molding cycle. This combination of cooling, twisting, and inflating operations allows spiral ridge formation without requiring separate processing steps, thereby managing process complexity while achieving the desired adaptability
Solution Approach 2:
The invention utilizes parameter changes in the resin's physical state during processing. The parison is extruded in a molten state, then cooled to a semi-solid state where it has sufficient rigidity to maintain shape, and finally reheated or kept pliable during inflation to allow the spiral ridge formation. These controlled parameter changes enable the complex spiral geometry to be formed without proportionally increasing process complexity
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 the formation of spiral ridges with a desired shape on the inner surface of containers without sagging or collapse, enhancing the container's appearance and structural reinforcement.
Implementation Method 1
a parison-forming die (hereinafter simply called a die) for extruding a molten thermoplastic resin into a tubular parison
Implementation Method 2
while cooling the inner surface of the parison
Implementation Method 3
twisting the parison hanging from the die and the raised ridges on the parison
Implementation Method 4
introducing gas pressure into the preform to stretch a blow molding portion into a final bottle shape
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
Provided is a process for producing a container having spiral ridges on an inner surface thereof, the process comprising a parison forming step of forming a hollow cylindrical parison having raised ridges on an inner surface thereof, a spiral ridge forming step of converting the raised ridges on the parison obtained in the parison forming step into spiral ridges, and a container forming step of inflating the parison obtained in the spiral ridge forming step from the inside thereof to form a container, the spiral ridge forming step comprising a clamping step of clamping the parison hanging from a die by gripping an outer surface of the parison after extrusion of the parison from the die in the parison forming step, and a rotating step of rotating the parison around the axis thereof while the parison clamped in the clamping step being kept clamped.