Liquid Blow Molding Preform Rupture Prevention
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Solution Overview
Problem
Conventional liquid blow molding devices risk preform rupture due to sudden pressurization during biaxial stretch blow molding, leading to potential failures in shaping resin containers.
Innovation Solution
A liquid blow molding device that limits the initial volume of pressurized liquid supplied to the preform to less than 50% of the final container volume, ensuring controlled stretching and preventing preform rupture by adjusting the liquid supply in conjunction with the stretch rod's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressurized liquid is suddenly supplied into the preform during stretching, then the preform is stretched in the radial direction, but the preform may rupture
Solution Approach 1:
The stretch rod performs preliminary stretching of the preform in the axial direction before the pressurized liquid is supplied. This preliminary mechanical deformation prepares the preform structure to withstand subsequent radial expansion from liquid pressure, preventing rupture during the blow molding process
Solution Approach 2:
The invention dynamically coordinates the timing and rate of liquid supply with the stretching process. The pressurized liquid is supplied at a controlled rate that matches the preform's deformation capacity, allowing the preform to progressively expand without exceeding its structural limits
2Reliability
If the volume of liquid supplied until stretching completion is limited to less than 50% of final container volume, then preform rupture is prevented, but the stretching process takes longer
Solution Approach 1:
The stretch rod and pressurized liquid supply operate simultaneously and continuously throughout the blow molding process. The stretch rod maintains continuous axial stretching while pressurized liquid continuously expands the preform radially, ensuring both actions complete together without idle time, thus preventing rupture while maintaining efficient cycle time
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
Enables confident biaxial stretch blow molding without preform rupture, ensuring the preform is reasonably stretched and molded into a predetermined shape, with specific guidelines for polypropylene and polyethylene terephthalate preforms.
Implementation Method 1
a pressurized liquid supply for supplying pressurized liquid to the preform disposed in the mold
Implementation Method 2
a stretch rod that stretches the preform disposed in the mold in the axial direction
Data Source
AI summary
A liquid blow molding device for liquid blow molding a resin preform into a container having a predetermined shape. The liquid blow molding device includes a mold in which the preform is disposed; a stretch rod that axially stretches the preform disposed in the mold (; and a pressurized liquid supply that supplies a pressurized liquid to the preform. The liquid blow molding device operates such that the amount of the liquid supplied from the pressurized liquid supply to the inside of the preform before completing the stretching of the preform by the stretch rod (22) is 50% or less of the amount of the liquid to be filled in the container after the completion of the liquid blow molding.