Pin-Cavity Adhesive Joint Assembly for Precise Positioning
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Solution Overview
Problem
Adhesive joints in lighting devices for motor vehicles face challenges due to volumetric shrinkage of adhesives during curing, which can alter the precise positioning of light sources and optical components, leading to a deterioration of the lighting effect.
Innovation Solution
A method involving the use of a rigid spacer positioned between the bottom surface of a cavity and the facing end of a pin, ensuring that the pin remains in its target position during adhesive curing by preventing repositioning towards the cavity bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is filled into the cavity to join the pin to the second component, then the pin is fastened in the target position, but the adhesive shrinkage during curing causes the pin to reposition towards the bottom surface of the cavity
Solution Approach 1:
A rigid spacer is applied to the bottom surface of the cavity before filling the adhesive. This spacer pre-establishes the correct distance between the bottom surface and the pin's facing end, preventing the pin from repositioning during adhesive curing. The spacer is removed after the adhesive cures, leaving the pin precisely positioned at the target distance.
Solution Approach 2:
The rigid spacer acts as an intermediary element during the joining process. It temporarily occupies the space between the bottom surface and the pin, controlling the adhesive distribution and preventing excessive adhesive from causing pin subsidence. The spacer mediates between the conflicting requirements of adequate adhesive coverage and precise position maintenance.
2Manufacturing precision
If the cavity depth is increased to accommodate pin displacement during curing, then the pin can maintain its position, but the overall device size increases
Solution Approach 1:
The rigid spacer is applied in advance to define the exact target position of the pin. This preliminary action eliminates the need for excessive cavity depth, as the spacer ensures the pin starts at the correct position and prevents any subsidence during curing. The cavity can therefore be optimized to the minimum required depth.
3Manufacturing precision
If the pin length is increased to extend beyond the cavity bottom surface, then the pin can maintain position, but the manufacturing complexity and adjustment difficulty increase
Solution Approach 1:
The mechanical solution of using an excessively long pin to prevent subsidence is replaced by a chemical-adhesive solution controlled by a rigid spacer. The spacer controls the adhesive distribution and pin position, allowing the pin length to be optimized for its functional requirements rather than being excessively long for positioning stability.
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
This method effectively maintains the precise positioning of the pin within the cavity, minimizing the impact of adhesive shrinkage on the vertical position of the pin, thus maintaining the desired lighting effect.
Implementation Method 1
A major issue concerning such adhesive joints is the effect of volumetric shrinkage of the adhesive during curing, caused e.g. by the evaporation of a solvent or by a cross-linking reaction.
Implementation Method 2
A major issue concerning such adhesive joints is the effect of volumetric shrinkage of the adhesive during curing, caused e.g. by the evaporation of a solvent or by a cross-linking reaction.
Data Source
AI summary
A method is provided to fasten a pin in a target position extending at least partially into a cavity with a distance (D) between a bottom surface of the cavity and a facing end of the pin. The pin is positioned at the target position, and the distance (D) is determined between the bottom surface of the cavity and the facing end of the pin in the target position. The pin is removed from the cavity, and a rigid spacer is applied on the bottom surface. A thickness of the rigid spacer equals the distance (D) between the bottom surface and the facing end of the pin in the target position. The adhesive is filled into the cavity onto the rigid spacer, and the pin is repositioned at the target position. The adhesive is then cured to obtain a joint between the pin and the second component.