Vehicle Belt Molding End Cap Locking Without Ultrasonic Welding
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Solution Overview
Problem
Existing methods for attaching a molding end cap to a vehicle body restrict material selection due to the need for materials with close melting points and can cause breakage with brittle resins like PBT.
Innovation Solution
A method involving a thermoplastic resin molding body and an end cap, where a protruding portion is formed on the molding body to prevent movement of the end cap by mechanical interference, allowing for diverse material selection and avoiding welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic welding is used to attach the end cap to the molding body, then the attachment strength is improved, but the material selection is restricted to materials with close melting points
Solution Approach 1:
The patent replaces the ultrasonic welding process (thermal-mechanical system) with a mechanical interference fit system consisting of a protruding portion on the molding body and a catch surface on the end cap. This mechanical substitution eliminates the need for thermal bonding, allowing materials with different melting points to be used while maintaining attachment strength.
Solution Approach 2:
The attachment mechanism is segmented into two independent components: a protruding portion formed on the molding body and a catch surface formed on the end cap. This segmentation allows each component to be manufactured from different materials independently, providing material selection flexibility while ensuring proper attachment through their interlocking geometry.
2Reliability
If pressure is applied by ultrasonic horn to weld the end cap, then the attachment is secured, but brittle resin end caps may be broken or cracked
Solution Approach 1:
The protruding portion is pre-formed on the molding body before the end cap is attached. This preliminary formation of the mechanical feature allows the end cap to be simply fitted onto the protrusion without requiring high-pressure application that could crack brittle materials, thus preserving end cap integrity while ensuring reliable attachment.
Solution Approach 2:
The patent replaces the high-pressure ultrasonic horn application system with a low-pressure mechanical interference fit system. The attachment is achieved through the geometric interlocking of the protruding portion and catch surface, eliminating the need for high-pressure application that could damage brittle end cap materials.
3Device complexity
If the end cap is inserted between the side wall portions, then the attachment structure is simplified, but material selection is further constrained
Solution Approach 1:
The patent replaces thermal welding systems with a mechanical interference fit system that utilizes the insertion space between side wall portions. This mechanical approach maintains the simplified attachment structure while eliminating material compatibility constraints, as no thermal bonding is required.
Solution Approach 2:
The attachment structure is segmented into the protruding portion on the molding body and the catch surface on the end cap, allowing each to be optimized for its specific function. This segmentation enables the use of different materials for the molding body and end cap without requiring thermal compatibility, while maintaining structural simplicity through the insertion-based assembly.
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 method allows for flexible material choice without welding, prevents end cap detachment, and controls rattling through controlled deformation and resin filling gaps, ensuring stable attachment.
Implementation Method 1
a protruding portion forming step of forming a protruding portion in the molding body, the protruding portion protruding on a vehicle exterior side relative to the vehicle interior side surface of the insertion portion of the end cap, by deforming a portion of the facing portion of the molding body
Implementation Method 2
movement of the end cap in a direction opposite to the insertion direction can be prevented based on engagement between the protruding portion of the molding body and the catch surface of the end cap
Data Source
AI summary
A method for producing a belt molding includes: inserting an insertion portion of an end cap into a molding body such that the insertion portion faces a facing portion of the molding body while the facing portion is positioned on a vehicle interior side relative to the insertion portion; and forming a protruding portion in the molding body. The protruding portion protrudes on a vehicle exterior side relative to a vehicle interior side surface of the insertion portion. The protruding portion is formed by deforming a portion of the facing portion which is closer to the lid portion of the end cap relative to the catch surface.