Blow-Molded Parison With Segmented Bottom Thickness
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Solution Overview
Problem
Blow molding methods struggle to create plastic containers with a squeezable body section and a bottom section having a desired wall thickness greater than the body section, as existing techniques either limit wall thickness variations or fail to maintain the desired thickness during the molding process.
Innovation Solution
A parison with a neck, shoulder, body, and bottom forming portion, where the bottom portion has increased sidewall and bottom wall thicknesses, is used in a blow molding method where compressed air is blown into the parison to stretch the body portion while restricting the bottom portion's movement, ensuring the bottom section maintains its desired thickness and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the bottom section wall thickness is increased to improve stability, then the container stability and luxury feel are improved, but the blow molding process becomes difficult to control and the body section may become too thin
Solution Approach 1:
The parison is divided into distinct sections with different wall thicknesses: a first parison section for the body portion with standard wall thickness, and a second parison section for the bottom portion with increased wall thickness. This segmentation allows each section to be optimized independently for its specific function while maintaining overall process control.
Solution Approach 2:
The parison is designed with non-uniform wall thickness distribution, where the bottom section has locally increased thickness compared to the body section. This local quality variation enables the bottom to provide enhanced stability and luxury feel while the body maintains appropriate thinness for squeezability and material efficiency.
2Shape
If the parison is stretched in both axial and radial directions during blow molding, then the container shape is formed, but the bottom section wall thickness cannot be maintained at the desired level
Solution Approach 1:
The parison is segmented into a first section and second section with different thicknesses, where the second section forms the bottom. This segmentation allows the bottom portion to maintain its thicker wall structure during the stretching process, as the increased initial thickness compensates for the radial and axial deformation that occurs during blow molding.
Solution Approach 2:
The parison is pre-formed with a non-uniform thickness distribution before blow molding, with the bottom section already having greater thickness. This preliminary action ensures that even after stretching during molding, the bottom section retains sufficient wall thickness to meet stability and luxury feel requirements.
3Ease of operation
If the container body is made with thin wall thickness for squeezability, then the container can be easily deformed by fingers, but the bottom section becomes slimmer and the container loses stability
Solution Approach 1:
The container is designed with spatially varying wall thickness: the body portion has thin walls for ease of squeezing and deformation, while the bottom portion has thick walls for stability and luxury feel. This local quality differentiation allows both contradictory requirements to be satisfied in their respective locations.
Solution Approach 2:
The container structure is segmented into functional zones with different thickness characteristics. The parison segmentation enables the body section to be thin-walled for user interaction while the bottom section is thick-walled for structural support, resolving the contradiction between squeezability and stability.
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 allows for the production of plastic containers with a squeezable body section and a stably thick bottom section, enhancing the container's stability and luxury feel, especially when empty, while maintaining the desired wall thickness and shape.
Implementation Method 1
blowing an air under pressure into the parison from the other end thereof so as to stretch the parison along the inner surface of the mold
Implementation Method 2
the body forming portion is stretched when a compressed air under pressure is blown into the parison in blow molding mold
Implementation Method 3
preparing blow molding mold which has such internal shape that is greater than external shapes of the shoulder forming portion and the body forming portion and is substantially same as an external shape of the bottom forming portion
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(b)
AI summary
[Object] To provide a parison for forming a container that includes a bottom of a thickness greater than that of a storage portion which has a squeezable property and to provide a blow-molding method using the parison. [Solution] A parison 50 is provided by injection molding in which external shapes of a neck forming portion 51 and a bottom forming portion 52 have the same external shapes as a neck section 20 and a bottom section 15 of a container 1 to be blow molded, respectively, and a body forming portion between the both forming portions has a thickness smaller than that of the bottom forming portion. A blow-molding method is provided which includes steps of supplying compressed air under pressure into the parison, thereby extending the body forming portion of the parison in an axial direction and moving the bottom forming portion of the parison toward the bottom inner surface of the mold, causing the outer bottom surface of the bottom forming portion to abut on the inner bottom surface of the molds and causing an outer periphery of the bottom forming portion to abut on the bottom inner periphery of the molds, and restricting the movement of the bottom portion by such abutments, and thereafter, stretching the body forming portion in a lateral direction, and bringing the shoulder forming portion and the body forming portion into contact with inner surfaces of the molds.