Vehicle Seat Frame-Foam Gap Layout for Dimensional Accuracy
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Solution Overview
Problem
Vehicle seat members with foamed resin molded bodies and embedded frame members face dimensional accuracy issues due to differing thermal expansion coefficients, leading to deformation and dimensional errors, especially in the width direction, which current methods inadequately address.
Innovation Solution
A method of manufacturing vehicle seat members involves embedding a frame member with a framework extending along the outer shape, forming gaps between the framework and the foamed resin molded body, either on the outer or inner sides, to absorb thermal contraction and expansion differences, thereby reducing deformation and enhancing dimensional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the frame member is integrally molded inside the foamed resin molded body, then the mechanical strength and structural integrity are improved, but the dimensional accuracy deteriorates due to differential thermal contraction and expansion
Solution Approach 1:
The patent introduces gaps that segment the contact interface between the frame member and foamed resin molded body. These gaps divide the continuous thermal stress transmission path into discrete segments, allowing differential thermal contraction and expansion to occur without causing cumulative deformation. The frame member remains integrally molded for strength, while the gaps prevent stress accumulation that would compromise dimensional accuracy.
Solution Approach 2:
The gaps act as intermediary spaces between the frame member and foamed resin molded body. These intermediary regions absorb and isolate the differential thermal movements, preventing direct stress transmission from the expanding/contracting foam to the rigid frame. This mediator approach allows both materials to undergo their natural thermal dimensional changes without mutual interference.
2Ease of manufacture
If the foamed resin molded body is allowed to contract freely after molding, then the ease of manufacture is improved, but the deformation increases leading to poor assembling accuracy
Solution Approach 1:
The gaps are pre-formed in the molding die before the foamed resin is injected. This preliminary action ensures that when the foam contracts after molding, the contraction is accommodated within the pre-defined gap spaces rather than causing unwanted deformation of the seat member. The dimensional accuracy is thus preserved while maintaining free contraction capability.
3Stability of the object's composition
If locking fixtures and connecting members are embedded in the foamed resin molded body, then the structural integration is improved, but the dimensional error increases due to large contraction in the seat longitudinal direction
Solution Approach 1:
The patent applies different local qualities to different regions: gaps are strategically positioned in areas experiencing large thermal contraction (particularly in the longitudinal direction where locking fixtures are located), while other regions maintain direct frame-foam contact for structural integration. This localized gap placement addresses the dimensional error problem in critical areas without compromising overall structural integrity.
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 effectively suppresses deformation of both the foamed resin molded body and the frame member, ensuring excellent dimensional accuracy and mechanical strength of the vehicle seat member.
Implementation Method 1
the foamed resin molded body has a property of slightly contracting after releasing from the mold
Implementation Method 2
individual thermal expansion coefficients are different
Data Source
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AI summary
Provided is a method for suppressing deformation by contraction after molding of a vehicle seat member comprising a foamed resin molded body embedding a frame member. The method manufactures a vehicle seat member (1) including a foamed resin molded body (100) and a frame member (200) at least a part of which is embedded therein in which the frame member (200) includes frameworks (250), (260) extending inside the foamed resin molded body (100) along an outer shape (400) of the vehicle seat member (1) in plan view. The method comprises forming gaps (101), (101), (102), (102) along an extending direction of the frameworks (250), (260) between at least a part of the frameworks (250), (260) and a part of the foamed resin molded body (100) located on an outer side of the at least a part of the frameworks (250), (260).