Blow Molding Die Segmented Core Prevents Neck Burrs
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Solution Overview
Problem
The formation of vertical burrs on the neck portion of resin containers during blow molding, which can lead to decreased airtightness and increased outer diameter of the blow core mold, resulting in fluid escape.
Innovation Solution
A blow molding mold with a blow core mold unit comprising a first core member with a smaller outer diameter than the neck portion, a second core member in contact with the neck mold, and a third core member that is slidable and pressurized by high-pressure fluid to seal the neck portion, preventing fluid escape and burr formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blow core mold outer diameter is increased to prevent fluid escape, then airtightness is improved, but vertical burrs are formed on the neck portion
Solution Approach 1:
The blow core mold is divided into multiple segments: a core member with smaller diameter for insertion, a sealing member with larger diameter for airtight sealing, and a burr prevention member. This segmentation allows each component to perform its specific function without compromising the neck portion dimensions.
Solution Approach 2:
Different portions of the blow core mold have different diameters tailored to specific functions. The core member has a smaller diameter matching the neck opening for insertion, while the sealing member has a larger diameter for airtight sealing, and the burr prevention member has controlled contact to prevent burrs. This local differentiation resolves the contradiction between airtightness and precision.
2Reliability
If the blow core mold outer diameter is increased to prevent fluid escape, then fluid containment is improved, but the neck portion outer diameter increases
Solution Approach 1:
The blow core mold is segmented into a core member for insertion, a sealing member for fluid containment, and a burr prevention member for dimensional control. The sealing member provides the necessary larger diameter for airtight sealing without transferring that expansion to the neck portion itself.
Solution Approach 2:
The sealing member acts as an intermediary between the core member and the neck portion. It provides the necessary sealing surface with larger diameter while the core member maintains the original neck portion dimensions, preventing fluid escape without increasing neck diameter.
3Reliability
If press-fitting is used to airtightly close the preform, then sealing is improved, but vertical burrs are formed on the neck portion
Solution Approach 1:
The sealing function is separated from the insertion function. The core member handles insertion with smaller diameter, while the sealing member provides airtight sealing with larger diameter. The burr prevention member specifically addresses surface quality, preventing burrs during the sealing process.
Solution Approach 2:
The sealing member has a localized larger diameter specifically at the sealing surface to provide airtight closure, while the core member maintains smaller diameter for insertion. The burr prevention member provides localized control at the neck portion contact area to prevent surface defects.
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
Prevents the escape of high-pressure fluid and formation of vertical burrs on the neck portion, ensuring airtightness and maintaining the original diameter of the neck portion during the blow molding process.
Implementation Method 1
a third core member provided in a space portion formed between an outer peripheral surface of the main body and an inner peripheral surface of the second core member so as to be slidable with respect to the outer peripheral surface of the first core member and the inner peripheral surface of the second core member and to contact with a top surface of the neck portion of the preform, and wherein the blow core mold unit has a second supply flow path for supplying the high-pressure fluid into the space portion
Data Source
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AI summary
A blow core mold unit 504 includes a first core member 506 configured to be loosely fitted to a neck portion 11 of a preform 10, a second core member 507 provided around the first core member 506 and in contact with a neck mold 501, and a third core member 508 provided in a space portion 521 formed between the first core member 506 and the second core member 507, and the blow core mold unit 504 has a second supply flow path 526, 514 for supplying a high-pressure fluid into the space portion 521.