Weather Strip Extrusion Die with Movable Core
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Solution Overview
Problem
Existing weather strip manufacturing methods result in non-uniform extrusion of rubber material, leading to corrugation and deterioration of the external appearance when bending is required to fit corner portions, compromising sealing performance.
Innovation Solution
An extrusion method using a die with a movable core that changes cross-sectional shape along the extrusion direction, allowing for varying wall thickness in the hollow sealing portion without compromising the external appearance, by adjusting the supply amount of rubber material per unit area to maintain uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wall thickness of the hollow sealing portion is increased to prevent crushing at corner portions, then the sealing performance is improved, but the extrusion amount becomes non-uniform causing corrugation and deterioration of external appearance
Solution Approach 1:
The patent employs a movable core that can dynamically change its position along the extrusion direction to adjust the cross-sectional shape of the hollow sealing portion. By moving the core between a first position (for side portions) and a second position (for corner portions), the system dynamically adapts the wall thickness distribution to match the structural requirements of different locations, preventing both crushing at corners and corrugation from non-uniform extrusion.
Solution Approach 2:
The patent applies local quality by creating different wall thickness characteristics at different locations of the hollow sealing portion. The movable core enables the side portions to have one wall thickness configuration optimized for uniform extrusion, while corner portions have increased wall thickness for enhanced crushing resistance, with each location having locally optimized properties suitable for its specific functional requirements.
2Reliability
If multiple dies with different discharge port diameters are used to create varying wall thickness, then the sealing performance at corner portions is improved, but the device complexity and manufacturing process become more complicated
Solution Approach 1:
Instead of using multiple static dies with different discharge port diameters, the patent employs a single die with a movable core that dynamically adjusts the internal cavity shape. This dynamic approach replaces the need for multiple specialized dies, simplifying the overall device structure while achieving the same functional outcome of variable wall thickness for different sealing requirements.
Solution Approach 2:
The movable core structure serves multiple functions: it acts as the internal support for the hollow sealing portion, defines the cavity shape, and enables variable wall thickness configuration. This single multi-functional component replaces what would otherwise require multiple specialized dies, reducing device complexity while maintaining the ability to produce different wall thickness profiles as needed.
Data Source
AI summary
An extrusion die includes a die and a core, and the core includes a movable core portion that is movable along an extrusion direction and a fixed core portion. The movable core portion has non-similar cross-sectional shapes at front and rear two positions along the extrusion direction. A first portion of the elongated weather strip is molded in a state where the movable core portion is disposed at an advance position, and a second portion of the elongated weather strip is molded in a state where the movable core portion is disposed at a retreat position. During the molding of the second portion, a supply amount per unit time of a material for the sealing portion to a molding space for the hollow sealing portion that is secured between the core and the die is set to be larger than that during the molding of the first portion.