Pin-Cavity Adhesive Joint with Rigid Spacer 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 position of light sources or optical components, thereby deteriorating the lighting effect.
Innovation Solution
A method involving the use of a rigid spacer, equal in thickness to the distance between the cavity bottom and the pin end in the target position, is applied to prevent the pin from repositioning during adhesive curing. This spacer eliminates adhesive from the volume below the pin, allowing only horizontal shrinkage effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to join pin to cavity, then components are fastened together, but volumetric shrinkage during curing causes position alteration
Solution Approach 1:
The adhesive joint is segmented into two functional zones: a lower support zone filled with adhesive for strength, and an upper precision zone above the pin tip where no adhesive exists to prevent shrinkage-induced position errors. This segmentation resolves the contradiction by separating the load-bearing function from the positioning function.
Solution Approach 2:
The harmful adhesive material is extracted from the critical upper zone above the pin tip, eliminating the source of shrinkage that causes position precision deterioration while preserving adhesive in the lower zone to maintain joint strength.
2Stability of the object's composition
If cavity depth is increased to accommodate pin displacement, then position stability is improved, but component size increases
Solution Approach 1:
Adhesive is extracted from the upper portion of the cavity above the pin tip, eliminating the source of shrinkage-induced displacement. This allows the cavity to be shallower while maintaining position stability, as the adhesive-free zone prevents volumetric changes that would otherwise require additional cavity depth to compensate.
3Reliability
If adhesive volume is increased to ensure complete filling, then joint reliability is improved, but shrinkage effect is amplified
Solution Approach 1:
The adhesive volume is segmented and restricted to the lower support zone only, excluding the upper precision zone. This segmentation ensures reliable adhesive bonding for joint strength while limiting the total adhesive volume to minimize shrinkage effects that would otherwise amplify position errors.
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 ensures that the pin remains precisely positioned in the target location, minimizing vertical displacement and maintaining the desired lighting effect, which is critical for compliance with regulations and customer specifications.
Implementation Method 1
A method involving the use of a rigid spacer, equal in thickness to the distance between the cavity bottom and the pin end in the target position, is applied to prevent the pin from repositioning during adhesive curing.
Implementation Method 2
joining a pin member of a first component to a second component with a cavity by means of an adhesive
Implementation Method 3
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 crosslinking reaction.
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
The invention relates to a method of joining a pin (1) member of a first component (1a) to a second component (2a) with a cavity (2) by means of an adhesive (3) in order to fasten the pin (1) in a target position extending at least partially into the cavity (2) with a distance (D) between the bottom surface (20) of the cavity (2) and the facing end (10) of the pin (1), wherein the method comprises at least the following steps: - positioning (100) the pin (1) to the target position, - determining (200) the distance (D) between the bottom surface (20) of the cavity (2) and the facing end (10) of the pin (1) in the target position, - removing (300) the pin (1) out of the cavity (2), - applying (400) a rigid spacer (4) on the bottom surface (20) of the cavity (2), wherein the thickness (40) of the rigid spacer (4) equals the distance (D) between the bottom surface (20) of the cavity (2) and the facing end (10) of the pin (1) in the target position, - filling (500) the adhesive (3) into the cavity (2) onto the rigid spacer (4), - repositioning (600) the pin (1) to the target position, - curing (700) the adhesive (3) and obtaining a joint between the pin (1) and the second component (2a).