Asymmetric Injection-Molded Button Resin Weld Line
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Solution Overview
Problem
Conventional injection-molded resin female snap buttons often crack when the pin of a button fastener passes through the through-hole during attachment to fabric due to weak weld lines formed during the molding process.
Innovation Solution
The button body is designed with asymmetric concave or convex portions on its outer surface, creating nonlinear weld lines that increase the joining strength by altering the flow resistance and meeting points of resin flows during molding, thereby reducing the likelihood of cracking when attached to fabric.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resin flows are joined in a conventional linear weld line configuration, then the molding process is simple, but the joining strength at the weld line is low and cracking occurs during attachment
Solution Approach 1:
The mold cavity is designed with asymmetric convex and concave portions that create an asymmetric weld line configuration. The weld line includes a first portion and a second portion with different lengths and orientations, preventing the formation of a straight linear weld line. This asymmetric design increases the joining strength by distributing stress more effectively across the weld line while maintaining manufacturing simplicity.
Solution Approach 2:
The weld line is designed to include curved portions rather than straight lines. The first weld line portion and second weld line portion are configured with different curvatures and orientations, creating a nonlinear weld line path. This curvature increases the weld line length and surface area, enhancing the joining strength between resin flows without significantly complicating the molding process.
2Strength
If the weld line is made nonlinear with asymmetric portions, then the joining strength increases, but the manufacturing precision requirements increase
Solution Approach 1:
The asymmetric convex and concave portions are pre-formed in the mold cavity before the injection molding process. These preliminary structural features guide the resin flow to automatically form the desired nonlinear weld line configuration with asymmetric first and second portions. This preliminary action ensures consistent weld line formation and reduces the need for post-processing adjustments, thereby maintaining manufacturing precision while achieving enhanced joining strength.
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
The nonlinear weld lines enhance the joining strength of the button body, reducing the occurrence of cracking when forces are applied during attachment, as the increased weld line length and area improve the resin flow integration.
Implementation Method 1
The resin material injected through the gate is once divided into left and right flows by the core, and the flows meet and join again behind the core
Implementation Method 2
the button body includes one or more concave portions or one or more convex portions on an outer surface of the button body, the concave portions or the convex portions being provided asymmetrically in the left and right half parts
Data Source
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AI summary
Provided is an injection-molded resin button, which does not crack or is unlikely to crack at attaching the button to a fabric. This invention relates to a button (10) comprising a button body (11) having a through-hole (13) at the center thereof. The button body (11) of the button (10) comprises a left half part (11L) and a right half part (11R), which are segmented left and right by a virtual straight line (L) passing through a gate position (17), on the button body (11), corresponding to a gate of a mold for molding the button (10) and the center (O) of the button body (11). The button body (11) includes one or more concave portions (21, 22) or one or more convex portions (31, 32) on an outer surface (11a) of the button body (11). The button (10) is characterized in that the concave portions (21, 22) or the convex portions (31, 32) are provided asymmetrically in the left and right half parts (11L, 11R). The button body (11) includes a nonlinear weld line (16) at least on the outer surface (11a).