Molded Plastic Seat Core for Uniform Chair Frame Strength
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Solution Overview
Problem
Knock-down chairs with wooden frames face issues such as hidden weaknesses in wood, leading to strength variations and wobbling, and the use of hardwoods is costly due to tracing regulations, while softwoods are prone to imperfections.
Innovation Solution
A seat core with a unitary body made of plastics via injection moulding, featuring a peripheral wall with recesses and reinforcing means, providing uniform strength and reducing regulatory costs by eliminating the need for hardwood traceability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If wooden frames are used for knock-down chairs, then the chairs can be flat packed and take less space during transportation, but the wooden frames have hidden weaknesses due to faults like knots that lead to strength variations and wobbling
Solution Approach 1:
The patent replaces traditional wooden frames with a moulded plastics seat core that has integrated recesses and strengthening members. This single-piece construction eliminates the need for separate wooden frame components that are prone to knots and weaknesses, providing consistent strength without the reliability issues of natural wood variations.
2Strength
If hardwoods are used to avoid drying and age imperfections, then the frame strength is improved, but the cost increases due to tracing regulations
Solution Approach 1:
The patent changes the material parameter from natural wood (hardwood or softwood) to moulded plastics. This material substitution eliminates the need for hardwood traceability regulations while maintaining frame strength through the integrated design of strengthening members within the plastics seat core structure.
3Ease of manufacture
If softwoods are used to reduce cost, then the manufacturing cost is reduced, but the frames are prone to drying and age imperfections that affect reliability
Solution Approach 1:
The patent uses moulded plastics as a cost-effective alternative to softwood, eliminating drying and age imperfections while maintaining affordability. The plastics material provides consistent durability without the reliability issues associated with natural wood degradation.
4Reliability
If a unitary plastics body is used instead of wooden frames, then uniform strength and reduced costs are achieved, but the complexity of moulding the unitary body with integrated recesses and strengthening members increases
Solution Approach 1:
The patent merges the seat core structure with integrated recesses and strengthening members into a single moulded plastics unitary body. This consolidation eliminates the need for separate wooden frame components and fasteners, achieving uniform strength while the moulding process efficiently creates the integrated complex geometry in one manufacturing step.
Data Source
AI summary
A seat core comprising a unitary body (1) including a peripheral wall (4, 5, 7) provided with a plurality of recesses (2), each recess being provided with at least one aperture (8) adapted to receive securing means for securing a chair component within the recess.