Vehicle Trim Element Molding Without Pre-Punched Injection Holes
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Solution Overview
Problem
Existing methods for manufacturing vehicle trim elements require additional operations such as punching or cutting holes in fiber-reinforced mats and result in protrusions or depressions from injection nozzles, complicating the process and increasing costs.
Innovation Solution
A method involving blending a mixture of wood fibers, polyacrylic binder, and polyester fibers, needling to create a mat, and performing hot shaping and back-injection in the same mold, eliminating the need for pre-punching and enhancing moldability and tensile properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If holes are punched or cut-off from the mat before injection, then the plastic can be injected through the mat, but this requires additional operations and leaves protruding or depression from the injection nozzle
Solution Approach 1:
The mat is pre-shaped through hot shaping to create a cavity-receiving surface before injection. This preliminary action prepares the mat structure to receive the injected plastic without requiring pre-punched holes, eliminating the need for additional operations and avoiding nozzle protrusions or depressions
Solution Approach 2:
Instead of creating holes in the mat and injecting through it, the invention inverts the approach by shaping the mat to have a recessed area that receives the injected plastic. The injection occurs into a cavity formed by the shaped mat surface rather than through the mat material itself
2Adaptability or versatility
If traditional injection through mat is used, then plastic parts can be attached, but additional operations for punching holes are required
Solution Approach 1:
The invention merges the mat shaping operation with the injection molding operation into a single integrated process. The hot shaping step creates the cavity-receiving surface, and the subsequent back-injection fills this cavity, combining two operations that would otherwise require separate tooling and sequential steps, thereby improving manufacturing efficiency
3Strength
If more polyester fibres are added to increase tensile properties, then moldability improves, but the cost and processing time may increase
Solution Approach 1:
The invention changes the processing parameters by applying hot shaping at elevated temperatures (typically 100-200°C) to the mat containing polyester fibers. This thermal parameter change enhances the moldability of the fiber mixture, allowing adequate tensile properties to be achieved with optimized fiber content and distribution without excessive processing time
Solution Approach 2:
The invention uses a composite material system combining natural fibers (wood, cotton, hemp) with synthetic polyester fibers and binders. This composite approach leverages the complementary properties of different materials: natural fibers provide bulk and sustainability, while polyester fibers contribute tensile strength and moldability, achieving balanced performance without excessive fiber content
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 simplifies the manufacturing process by eliminating the need for pre-punching, improving moldability and tensile properties, and reducing tooling and energy costs while ensuring effective adhesion and air permeability for subsequent processes.
Implementation Method 1
The polyacrylic binder is, for example, a polyacrylic thermosetting resin. The polyacrylic thermosetting resin, for example, has a temperature of setting comprised between 135°C and 160°C. When cured, said resin is more resistant to higher temperature.
Implementation Method 2
needling of the mixture to obtain a mat. The needling step allows entangling the fibres, adding moldability and tensile properties for subsequent moulding.
Data Source
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AI summary
The invention relates to a method for manufacturing a trim element of a vehicle, comprising the steps of: • blending (100) of a mixture comprising wood fibres, polyacrylic binder and polyester, preferably PET, fibres; • needling (110) of the mixture to obtain a mat; • hot shaping (120) of the mat into a trim part; and • back-injection (130) of additional elements on the trim part to form the trim element, The hot shaping and back-injection steps (120, 130) are performed in the same mould. The invention further relates to an associated trim element.