Assembly Injection Molding for Optical Light Guides
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Solution Overview
Problem
Conventional multi-component injection molding processes for producing composite components with light guides result in light absorption at the material transition interface, leading to non-uniform illumination along the length of elongated light guides due to material bonding, which reduces the amount of light reflected to the exit surface.
Innovation Solution
The method involves an assembly injection molding process where the carrier and light guide are connected in a form-fitting, non-detachable manner without a material connection, using separate injection steps and materials that do not adhere to each other, such as polar and non-polar plastics, to minimize light absorption and ensure uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multi-component injection molding process is used to produce composite component with carrier and light guide, then integral component connection is achieved, but light absorption occurs at material transition interface leading to non-uniform illumination
Solution Approach 1:
The patent extracts the harmful material transition interface by separating the light guide and carrier into distinct components connected via snap-fit mechanism. The light guide is removed from direct material bonding with the carrier, eliminating the source of light absorption while maintaining structural connection through the retention mechanism.
Solution Approach 2:
The composite component is segmented into separate carrier and light guide components that are assembled rather than molded as one piece. This segmentation prevents the creation of a material transition interface, allowing each component to be optimized independently while maintaining their functional relationship through mechanical connection.
2Strength
If conventional fastening elements are used to attach light guide to carrier, then secure connection is achieved, but assembly complexity and component count increase
Solution Approach 1:
The fastening function is merged into the carrier structure itself through integrated retention elements (springs and lugs). Instead of separate fastening components, the carrier incorporates the retention mechanism directly, reducing part count while maintaining secure connection of the light guide.
Solution Approach 2:
The retention elements automatically engage and secure the light guide to the carrier through spring-loaded lugs that snap into corresponding recesses. The system is self-securing without requiring additional fastening operations or components, as the carrier's own structure provides the retention mechanism.
3Stability of the object's composition
If material connection is created between carrier and light guide, then integral component is achieved, but light absorption at interface reduces reflectivity
Solution Approach 1:
The harmful material transition interface is extracted and replaced with a mechanical snap-fit connection. The light guide and carrier remain as distinct materials without creating a bonded interface, eliminating the light absorption problem while maintaining stable component integration through the retention mechanism.
Solution Approach 2:
The snap-fit retention elements act as intermediaries between the light guide and carrier, providing mechanical connection without creating a material bond. This intermediary mechanism allows the two components to remain materially separate, preventing light absorption at the interface while maintaining stable integration.
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 approach reduces light absorption at the interface, allowing for consistent illumination along the length of the light guide, as there is no material transfer or adhesion between the carrier and light guide, maintaining reflectivity and ensuring even illumination of the interior trim component.
Implementation Method 1
The light guide (11) has a light coupling point at which a light source is arranged and a light exit point. The light guide (11) extends from the light coupling point to the light exit point... a certain proportion of light is absorbed at the contact surface between the light guide and the carrier due to the material transition
Implementation Method 2
The two plastic materials used in the injection molding process are chosen such that the second plastic material has a lower melting temperature and higher shrinkage than the first plastic material, creating a gap between the two components
Data Source
Figure 1~2
Figure 3~5
AI summary
A method for producing a component assembly (3) consisting of a carrier (9), e.g., an aperture, and an optical fiber (11), comprising a first process step (I) in which a carrier-plastic component is injected into a main chamber (31) that replicates the negative shape of the carrier (9), leaving a sub-chamber (33) that replicates the negative shape of the optical fiber (11), and a second process step (II) in which the optical fiber-plastic component is injected into the sub-chamber (33). It is essential that the component assembly (3) is produced in an assembly injection molding process in which the carrier (9) and the optical fiber (11) are positively and permanently joined without a material bond.