Motor Vehicle Trim Panel Foam Degradation Prevention
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Solution Overview
Problem
The existing method for producing motor vehicle interior trim panels using reaction injection molding (RIM) faces challenges with the degradation of coating layers during foam expansion, leading to increased manufacturing costs and reduced panel resistance due to the separate bonding step of these layers.
Innovation Solution
The method involves creating face and back stacks with impermeable reinforcing layers and fibrous layers bonded by thermoplastic resin, coated with protective layers, which are thermoformed together to prevent foam degradation and integrated into the RIM process, eliminating the need for a separate bonding step and enhancing panel resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coating layers are fixed on shells during blank conformation using thermoplastic material, then the bonding step is eliminated, but the foam expansion degrades the coating layers
Solution Approach 1:
The coating layers are applied to the shells during the blank conformation step, before the foam expansion occurs. This preliminary action integrates the coating application into the existing manufacturing process, eliminating the need for a separate bonding step while positioning the coating layers to withstand the subsequent foam expansion without degradation.
Solution Approach 2:
The invention utilizes the temperature parameter during blank conformation to activate the thermoplastic material, which bonds the coating layers to the shells. The temperature is controlled to be sufficient for bonding but managed to prevent degradation during the subsequent foam expansion process, thereby maintaining coating layer integrity while achieving process integration.
2Reliability
If coating layers are bonded in a subsequent manufacturing step, then the foam expansion does not degrade the layers, but the manufacturing cost increases
Solution Approach 1:
The invention merges the coating layer application step with the blank conformation step by applying the coating layers to the shells during conformation. This integration eliminates the need for a separate subsequent bonding step, thereby reducing manufacturing cost while the controlled process parameters ensure the coating layers remain protected from foam expansion degradation.
3Strength
If foam penetrates into the thickness of porous fibrous material, then bending resistance is improved, but coating layer degradation occurs
Solution Approach 1:
The coating layers are applied to the shells during the blank conformation step, before foam expansion occurs. This timing allows the foam to penetrate the porous fibrous material and achieve bending resistance without coming into contact with and degrading the coating layers, as the coating is already in its final position on the shell surface.
Solution Approach 2:
The invention applies coating layers specifically to the shell surfaces where they are needed for protection and aesthetics, while allowing the foam to penetrate the porous fibrous material in the core regions to achieve bending resistance. This localized application ensures coating layer integrity in areas subject to foam expansion while maintaining structural strength where foam penetration is beneficial.
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 manufacturing costs and maintains high bending resistance by preventing foam degradation of the coating layers and providing localized reinforcement, resulting in a robust and cost-effective panel structure.
Implementation Method 1
compressing each of said stacks between two plates brought to the melting temperature of said material
Implementation Method 2
injecting into said volume a precursor mixture of rigid polyurethane foam so as to form a cellular core, after expansion and cross-linking of the foam
Implementation Method 3
providing in particular the presence of a component for binding the fibers based on thermoplastic material fusible at the forming temperature of said blanks
Data Source
Figure 1
AI summary
The present application relates to a method comprising the following steps: producing an obverse stack (A) and a reverse stack (B), each comprising a reinforcement layer (2a, 2b) and a fibrous layer (3a, 3b), the outer faces of said reinforcement and porous layers being coated with a porous protective layer (41a, 42a, 41b, 42b), respectively; compressing each of said stacks, wherein the protective layer of the reinforcement layer in the obverse stack is either coated with an obverse coating layer (5a) or left uncoated such that it forms, by itself, the obverse coating layer, in order to obtain an obverse shell (8a) and a reverse shell (8b) defining, by an overlapping of their respective edges, a closed volume; disposing said shells opposite each other in a reaction injection mould and injecting into said volume a precursor mixture of rigid polyurethane foam to form a cellular core (6).