Vehicle Seat Core Member Shrinkage Compensation

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Solution Overview

Problem

The dimensional accuracy of vehicle seat core members is compromised due to shrinkage of molded articles made from thermoplastic resin, leading to misalignment of securing attachments and difficulties in securing the seat to a vehicle.

Innovation Solution

Creating a space or notch outside the molded article during or after molding, where the securing attachments are embedded, to prevent warping and deformation caused by shrinkage, and using a connecting member with a tension strength of 200 N/mm² or higher to maintain dimensional accuracy and resist impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If securing attachments and connecting members are embedded in a molded article of expanded beads that shrinks during molding, then the molded article can be formed with integrated securing attachments, but the connecting members may be bent by shrinkage or dimensional errors occur in the molded article after curing

Engineering Contradiction:

Improveintegral molding capabilityVSAvoiddimensional accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by creating spaces or notches in the mold before molding the expanded beads. These spaces are positioned at locations where shrinkage is expected to occur, allowing the mold to compensate for shrinkage and maintain dimensional accuracy of the securing attachments and connecting members during the molding process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical parameters of the mold by creating spaces or notches with specific dimensions and positions. These parameter changes allow the mold to accommodate shrinkage of the thermoplastic resin while maintaining the dimensional accuracy of embedded components, resolving the contradiction between integral molding capability and manufacturing precision

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the molded article shrinks by a large degree in the longitudinal direction, then the molded article can be formed, but the dimensional error of securing attachments disposed near both ends becomes large, causing misalignment

Engineering Contradiction:

Improvemolding efficiencyVSAvoiddimensional accuracy of securing attachments

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the mold into sections with spaces or notches at strategic locations, particularly near the securing attachments at both ends. This segmentation allows different parts of the mold to shrink independently, preventing cumulative dimensional errors and maintaining alignment of securing attachments with vehicle mounting points

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating spaces or notches with specific dimensions and positions tailored to the local shrinkage characteristics of different mold sections. The spaces are strategically positioned near securing attachments to provide localized compensation for shrinkage, ensuring dimensional accuracy where it is most critical for alignment with vehicle attachments

Inventive Principle:

Principle #3Local quality

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 ensures excellent dimensional accuracy and enhanced resistance to pull-loads, reducing dimensional errors and improving the structural integrity of the vehicle seat core member.

Implementation Method 1

Since a molded article of expanded beads made of thermoplastic resin shrinks after molding, the dimension of the molded article of expanded beads needs to be recovered by a curing step after molding

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP3196069B1Method for manufacturing vehicle seat core member and vehicle seat core member

Publication Date: 2019.10.30 JSP CORP

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AI summary

The present invention provides a method for manufacturing a vehicle seat core member integrally molded to include a securing attachment embedded in a molded article of expanded beads made of thermoplastic resin, the method being used to manufacture a vehicle seat core member having an excellent dimensional accuracy. A method for manufacturing a vehicle seat core member according to the present invention is for manufacturing a vehicle seat core member including securing attachments disposed near both ends in a front portion of the seat core member made of a molded article of expanded beads, the securing attachments being connected by an embedded connecting member extending in the longitudinal direction of the seat core member. The securing attachment includes a base embedded in the molded article of expanded beads, an upright frame joined to the base to extend out of the molded article of expanded beads, and a securing portion extending from the upright frame to project away from the molded article of expanded beads. The method includes creating, during or after molding the molded article of expanded beads, a space or a notch in an outer side of the upright frame of the securing attachment of the molded article of expanded beads in the longitudinal direction of the seat core member, the notch extending toward an outer side in the longitudinal direction of the seat core member.