Weather Strip Core Mold Withdrawal Design
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Solution Overview
Problem
Conventional weather strips face challenges in maintaining appearance quality and sealing capability due to issues with core mold withdrawal, increased load differences, and productivity costs, particularly when forming hollow sealing portions and connecting injection molded portions.
Innovation Solution
A weather strip design with an injection molded portion having a core withdrawing hole that is 0.5 mm to 3.0 mm wide and 25% to 45% of the hollow sealing portion's circumferential length, allowing for easy core mold withdrawal without the need for preforming the core withdrawing hole or using sheet materials, and made from soft olefin-based thermoplastic elastomer to equalize repulsive forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a core withdrawing hole is provided in the hollow sealing portion to enable core mold withdrawal, then the core mold can be withdrawn after injection molding, but the appearance quality deteriorates due to the visible hole and the sealing capability may be compromised
Solution Approach 1:
The core withdrawing hole is extracted from the hollow sealing portion and relocated to the injection molded portion, separating the withdrawal function from the appearance-critical sealing portion. This allows the core mold to be withdrawn while the hollow sealing portion maintains its intact appearance and sealing capability.
Solution Approach 2:
The injection molded portion serves as an intermediary structure that facilitates core mold withdrawal. By providing the core withdrawing hole in this non-critical portion, the system enables mold removal without directly compromising the appearance or sealing function of the hollow sealing portion.
2Ease of operation
If the core body is formed in a taper shape to ease insertion, then insertion becomes easier, but the insertion margin and width of the injection molded portion are widened thereby lowering productivity
Solution Approach 1:
The core body is preliminarily formed with a substantially cylindrical shape rather than a taper shape, eliminating the need for gradual insertion. The core withdrawing hole provides sufficient clearance for direct insertion and withdrawal, preventing material adhesion issues while maintaining tight connection without requiring widened dimensions.
3Shape
If sheet material is used to connect extrusion molded portions, then the width dimension of connecting portion is reduced, but the hollow portion becomes clogged causing localized load increase and requiring additional cutting processes
Solution Approach 1:
The sheet material connecting method is replaced by direct injection molding that forms the connecting portion as an integral part of the weather strip. This extracts the intermediate connecting element and creates a seamless structure where the injection molded portion directly connects the extrusion molded portions, eliminating hollow portion clogging and additional cutting processes.
4Ease of manufacture
If a large opening area is provided for the core withdrawing hole, then core mold withdrawal becomes easier, but the air discharging function is compromised and appearance quality deteriorates
Solution Approach 1:
The core withdrawing hole is designed with specific dimensional characteristics tailored to its location in the injection molded portion. The hole dimensions are optimized to provide sufficient clearance for core mold withdrawal while maintaining an acceptable appearance in the non-critical injection molded portion, rather than using a uniformly large opening that would compromise overall appearance.
Data Source
AI summary
A method for producing a weather strip including an extrusion molded extrusion molded portion, an injection molded portion which is formed by a molding device having a plurality of mold members and connects both ends of the extrusion molded portions in a straight line shape, a mounting base portion which is mounted on a circumferential edge of an opening of a body or a circumferential edge of an opening/closing member for opening and closing the opening, and a hollow sealing portion which protrudes from the mounting base portion, and is pressed against an opposite member when the opening/closing member for opening and closing the opening is closed.