Multi-Layer Injection Molded Headlight Lens
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Solution Overview
Problem
Current methods for producing optical lens elements, such as headlight lenses, face challenges in reducing production costs and cycle time while maintaining high quality and optical properties, particularly in achieving low reject rates and precise geometric and optical tolerances for industrial-scale production.
Innovation Solution
The method involves injection molding transparent plastic using a first injection mold to form a pre-molded part, which is then cooled and overmolded in a second injection mold to create an optical lens element with a specific layer thickness distribution and sprue/runner/gate configuration, allowing for efficient production of multiple lens elements with improved process stability and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-layer injection molding is used to compensate sink marks and reduce mold opening pressure, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The lens element is divided into multiple injection-molded layers with different wall thicknesses. The inner layer has greater wall thickness than the outer layers, creating a specific layer thickness distribution (s2=1/4 s, s1=1/2 s, s3=1/4 s) that compensates for sink marks and reduces mold opening pressure while maintaining contour accuracy.
Solution Approach 2:
Different regions of the lens element have different wall thicknesses tailored to their specific requirements. The inner layer has greater thickness where structural support is needed, while outer layers have reduced thickness to minimize cooling time and compensate for sink marks in previously molded regions.
2Productivity
If wall thickness is reduced in outer layers to decrease cooling time, then productivity is improved, but manufacturing precision may deteriorate
Solution Approach 1:
The wall thickness parameter is optimized differently for inner and outer layers. Outer layers have reduced wall thickness (1/4 of total thickness each) to minimize cooling time, while the inner layer maintains greater thickness (1/2 of total thickness) to provide structural support and ensure contour accuracy through sink mark compensation.
3Productivity
If industrial-scale production is implemented to reduce costs, then productivity is improved, but maintaining quality standards becomes more difficult
Solution Approach 1:
The multi-layer injection molding process with optimized wall thickness distribution is designed to preemptively compensate for sink marks and reduce mold opening pressure before production issues arise. This preliminary structural design ensures consistent quality outcomes across large production volumes by built-in process 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 approach enables the production of high-quality optical lens elements with reduced cycle time and costs, achieving a low reject rate and maintaining stringent optical and geometric tolerances, making the process suitable for industrial-scale production of vehicle headlight lenses.
Implementation Method 1
an injection-molding material is injection molded using a first injection mold to form a pre-molded part
Implementation Method 2
the pre-molded part is then cooled outside the first injection mold
Data Source
AI summary
The invention relates to a method for producing a lens element (2), in particular for illumination purposes, in particular for producing a headlight lens (2) for a vehicle headlight, in particular for a motor vehicle headlight (1).