Screwless Chair Assembly Using Snap-Fit Geometry for Flat-Pack Storage
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Solution Overview
Problem
Pre-assembled chairs require significant effort and are prone to errors during assembly and disassembly, leading to potential safety concerns due to the repeated stress on components, and they occupy substantial space during storage and transportation.
Innovation Solution
A screwless chair design featuring a seat back, seat base, and armrest pieces connected via metal rivets or hinges, with hook and groove pieces and protrusion and receiving tubes for assembly without tools, allowing for compact packaging and easy setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If chairs are designed as pre-assembled packages to reduce storage and transportation size, then volume efficiency is improved, but assembly complexity and error probability increase
Solution Approach 1:
The chair is divided into modular components (seat back, seat base, armrest pieces) that can be easily separated and reassembled. Each component is designed with specific connection features (protrusion pieces, receiving tubes, hook pieces, groove pieces) that enable simple snap-fit assembly without requiring complex tools or procedures.
Solution Approach 2:
Traditional fastening elements such as screws, screw drivers, and other tools are completely removed from the assembly system. The connection mechanism relies solely on the inherent geometric features of the components themselves, eliminating the need for external fastening tools and reducing assembly complexity.
2Volume of moving object
If chairs are designed as pre-assembled packages for compact storage, then storage efficiency is improved, but assembly time and consumer effort increase
Solution Approach 1:
The connection features (protrusion pieces, receiving tubes, hook pieces, groove pieces) are pre-formed during manufacturing, so that during assembly the consumer only needs to perform simple alignment and insertion actions. The complex geometric features are already prepared, eliminating the need for on-site fabrication or complex manipulation.
Solution Approach 2:
The chair components are designed to assemble themselves through simple user actions. The protrusion pieces naturally guide into the receiving tubes, and the hook pieces slide into the groove pieces, with the geometry of the parts themselves providing the assembly guidance and locking mechanism, requiring minimal user effort and expertise.
3Strength
If traditional screw-based assembly is used to ensure chair sturdiness, then connection strength is improved, but repeated assembly and disassembly cause component deterioration
Solution Approach 1:
The connection features are designed as single-use, non-reusable elements that are discarded after one assembly cycle. The protrusion pieces and receiving tubes are configured so that once inserted and locked, they cannot be removed and re-inserted. This eliminates wear and deterioration from repeated assembly/disassembly, as each connection is designed for one-time use only.
Solution Approach 2:
Instead of designing for reversible assembly (screws that can be tightened and loosened), the invention uses irreversible connection geometry. The protrusion pieces are shaped to fit into receiving tubes in a single direction, and the hook pieces are designed to slide into groove pieces and lock in place, preventing removal and reassembly. This inversion of the traditional reversible fastening approach eliminates cumulative wear.
4Reliability
If screw-based fastening is used to secure chair components, then assembly reliability is improved, but ease of operation deteriorates due to tool requirements
Solution Approach 1:
All fastening tools (screws, screw drivers, hex keys, etc.) are completely removed from the assembly system. The connection mechanism relies solely on the inherent geometric features of the components themselves, eliminating the need for external fastening tools and reducing assembly complexity.
Solution Approach 2:
The chair components are designed to assemble themselves through simple user actions. The protrusion pieces naturally guide into the receiving tubes, and the hook pieces slide into the groove pieces, with the geometry of the parts themselves providing the assembly guidance and locking mechanism, requiring minimal user effort and expertise.
Data Source
AI summary
Present invention teaches a screwless chair where the unassembled product can come in a flat package, reducing the size of storage and adding to the ease of transportation. No screws are needed for the chair of present invention; no tools are needed for the assembly/disassembly when a user unfolds the seat back from the seat base, slides the hook pieces along the groove pieces and set the seat back down by inserting the protrusion pieces to the corresponding receiving tubes; the locking tabs on the protrusion pieces provide the locking function when inserting into the receiving tubes. Errors in setting up the chair can be avoided. The ease of setting up, and thus the sturdiness and the safety of the chair, is not affected by repeated disassembly/re-assembly.