Light-Transmissive Trim Part Co-Injection Molding

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Solution Overview

Problem

The automotive industry faces challenges in producing cost-effective and easily manufacturable light and trim parts for vehicle interiors with limited installation space, requiring a method to reduce the number of individual parts while maintaining functionality and aesthetic appeal.

Innovation Solution

A method involving thermoforming of distinct decorative films within separate tools, followed by their integration in an injection molding system with a transparent material for back-injection, forming a light-pervious panel with a diffusing screen, which reduces the number of components and simplifies production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If multiple separate components (decorative panels, light guides, partitioning elements) are used to create light-transmissive trim parts, then the functionality and aesthetic appeal are maintained, but the number of individual parts increases and manufacturing complexity increases

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidnumber of individual parts
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent combines multiple separate components (first decorative film, second decorative film, light-guiding elements, and transparent base part) into a single integrated paneling part through co-injection molding. The transparent base part is molded in the first injection process, and the decorative films are molded in a second co-injection process, creating one unified component that performs multiple functions (decoration, light guidance, and light transmission) without requiring separate assembly of multiple parts.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated paneling part serves multiple functions simultaneously: the first and second decorative films provide aesthetic appearance, the transparent base part enables light transmission, and the embedded light-guiding elements distribute ambient lighting. This multi-functional design eliminates the need for separate components for each function, reducing part count while maintaining full functionality.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Area of stationary object

If multiple separate components are assembled to form light-transmissive trim parts, then functional requirements are met, but installation space and assembly complexity increase

Engineering Contradiction:
Improveinstallation spaceVSAvoidnumber of individual parts
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent merges multiple functional elements into a single integrated paneling part through co-injection molding. The transparent base part with embedded light-guiding elements and decorative films is created as one unified component, eliminating the need for separate assembly of multiple parts and reducing the space required for installation and assembly operations.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If decorative films are thermoformed in separate tools and then assembled, then aesthetic quality is maintained, but production time and manufacturing complexity increase

Engineering Contradiction:
Improveaesthetic qualityVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs preliminary thermoforming of the decorative films within the injection molding tools themselves before the final molding process. The films are pre-shaped and positioned in the molds, then the transparent base part is injected and bonded to the pre-formed decorative films in a co-injection process. This preliminary action ensures aesthetic quality while integrating the process into a single production step, improving efficiency.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent combines the thermoforming and molding operations into a single integrated process. The decorative films are thermoformed and molded simultaneously with the transparent base part in a co-injection molding process, eliminating separate assembly steps and improving production efficiency while maintaining aesthetic quality through precise integral forming.

Inventive Principle:
Principle #5Merging (Combining)

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 allows for the cost-effective and efficient manufacture of integrative decorative panels with ambient lighting, reducing the number of individual parts and enhancing manufacturing simplicity, while providing a visually appealing and functional lighting and trim part for vehicle interiors.

Implementation Method 1

back-injecting the first and second decorative foil together with a transparent material in exactly one injection process

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

thermoforming the first and second decorative foil within the respective tools included

Methodology Applied
Scientific EffectThermoforming:

Implementation Method 3

forming a light-pervious panel with a diffusing screen

Methodology Applied
Scientific EffectLight diffusion: Scattering

Data Source

PatentEP3107760B1Method for producing a light-transmissive trim part and lighting and trim part
Publication Date: 2018.03.14 VOLKSWAGEN AG
  • EP3107760B1 patent drawingFigure 1
  • EP3107760B1 patent drawingFigure 2
  • EP3107760B1 patent drawingFigure 3

AI summary

Method for producing a light-transmissive panelling part (10) for the passenger compartment (20) of a motor vehicle (100), which comprises the following method steps: • - providing a first decorative film (1) and a second decorative film (2) that is different from the first decorative film (1), in each case in a mould (S1); • - thermoforming (S2) the first and second decorative films (1, 2) within the respective moulds; • - placing (S3) the first and second decorative films (1, 2) in an injection-moulding system, wherein the first and second decorative films (1, 2) are positioned in a predetermined arrangement in relation to one another; a step of joint in-mould lamination (S4) of the first and second decorative films (1, 2) with a transparent material in just one injection-moulding operation is provided for this purpose. Furthermore, a lighting and panelling part (40) for the passenger compartment (20) of a motor vehicle (100) is explained. A motor vehicle (100) that comprises a lighting and panelling part (40) is also described.