Vehicle Interior Part Molding with Elastomeric Padding
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Solution Overview
Problem
Existing methods for molding vehicle interior parts, such as dashboards, face challenges in achieving a balance between cost-effectiveness, resistance to scratching and chemical agents, and softness to the touch, with prior solutions either being costly or resulting in a rigid and low-quality finish.
Innovation Solution
A molding method using a cube mold with two injection chambers to create a sandwich structure comprising a thermoplastic base, a thermoplastic elastomer intermediate layer, and a lining film that adheres to the mold through vacuum, compressed air, and heating, ensuring precise adhesion and a soft, durable finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If leather or imitation leather coverings are used, then softness and comfort are improved, but cost increases significantly
Solution Approach 1:
The part is divided into two functional zones: a rigid plastic base providing structural support and an intermediate elastomeric layer providing softness. This segmentation allows each material to perform its optimal function without requiring expensive leather coverings.
Solution Approach 2:
The invention uses a composite structure combining thermoplastic material for the base with a thermoplastic elastomer intermediate layer. This composite approach achieves both structural integrity and tactile softness while remaining cost-effective compared to leather solutions.
2Ease of manufacture
If photoengraved or embossed thermoplastic material is used, then cost is reduced, but resistance to scratching and chemical agents deteriorates
Solution Approach 1:
A lining film is applied to the elastomeric intermediate layer to provide protective functionality. This film barrier protects against scratching and chemical agents while the underlying elastomeric layer maintains cost-effectiveness compared to leather.
3Reliability
If thin pressed films creating leather effect are applied to plastic base, then resistance to abrasion and scratching is improved, but softness deteriorates due to extreme rigidity
Solution Approach 1:
Different layers are assigned different mechanical properties: the plastic base provides rigidity where structural support is needed, while the elastomeric intermediate layer provides softness where tactile comfort is required. This local differentiation resolves the contradiction between protection and comfort.
Solution Approach 2:
The three-layer composite structure (plastic base + elastomeric intermediate layer + lining film) combines materials with different properties to simultaneously achieve structural integrity, tactile softness, and surface protection.
4Ease of operation
If foam with built-in sponge is used in injection process, then softness is improved, but reliability deteriorates as foam is damaged upon contact with injected plastic material
Solution Approach 1:
The elastomeric intermediate layer is injected and allowed to cool and stabilize before the lining film is applied. This preliminary action ensures the foam structure is fully formed and stable, preventing damage during subsequent processing steps.
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
The method produces a cost-effective, abrasion-resistant, and chemically durable part with a soft touch, similar to leather-lined interiors, while maintaining high quality and customization options, and ensures reliable and precise molding with the lining film acting as both an aesthetic and protective element.
Implementation Method 1
a lining film (48), said lining film (48) having been deformed so as to adhere to said second injection chamber (12) by its external side (52) to an esthetic side (56) of said second injection chamber (12), opposite said functional wall (44)
Implementation Method 2
said lining film (48) having been deformed so as to adhere to said second injection chamber (12) by its external side (52) to an esthetic side (56) of said second injection chamber (12), opposite said functional wall (44)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Injection molding method of a part (6) for vehicle interiors, comprising the steps of: - arranging a mold (4) having a first injection chamber (8) shaped so as to define in negative a base (36) of said part (6), - injecting thermoplastic material, such as polypropylene, into said first injection chamber (8), - extracting the base (36) from the first injection chamber (8) and placing it in a second injection chamber (12) on the side of a functional wall (44) of said second injection chamber (12), - inserting a lining film (48) in said second injection chamber (12) and deforming it so as to arrange it, on the side of an outer surface (52) thereof, adhering to an esthetic wall (56) of the second injection chamber (12) opposite the functional wall (44), - injecting an intermediate layer (80) of plastic material, such as a thermoplastic elastomer (TPE), in a gap (84) between an inner wall (88) of the base (36) facing the lining film (48), and an inner surface (92) of the lining film (48) opposite said outer surface (52) so as to create a single sandwich structure, wherein said intermediate layer (80) is present between the lining film (48) and the base (36), - the intermediate layer (80) having lower hardness than the base (36) and forming a yielding padding for the lining film (48).