KD chair and stool construction
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Solution Overview
Problem
Existing ready-to-assemble furniture technologies face challenges in reducing assembly time, increasing stability, and minimizing transportation and storage costs due to the large number of individual parts and insufficient torque at joints, leading to weak and unstable structures.
Innovation Solution
The use of factory-manufactured sub-assemblies, metal rods, bolts, and removable covers for chairs, which allow for nesting and reduced assembly complexity, resulting in a stronger and more stable unit with fewer joints, and enabling efficient packaging and reduced freight costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual parts are used for assembly, then the furniture can be disassembled for shipping, but the number of joints increases leading to weaker and less stable structures
Solution Approach 1:
The chair is divided into major sub-assemblies (seat, backrest, leg assemblies) that can be independently manufactured and shipped, then connected through a small number of standardized joints using the attaching rod system, reducing total joint count while maintaining disassembly capability
Solution Approach 2:
Sub-assemblies are pre-manufactured and pre-treated (e.g., pre-drilled holes, pre-applied connectors) at the factory, so that final assembly requires only insertion and tightening of the attaching rod, minimizing on-site assembly complexity and joint creation
2Ease of manufacture
If multiple individual parts are connected together, then the furniture can be assembled from components, but assembly time increases significantly
Solution Approach 1:
Multiple connection functions are merged into a single attaching rod system that simultaneously secures multiple sub-assemblies (seat to backrest, legs to frame) through sequential tightening, reducing the number of separate assembly operations required
Solution Approach 2:
The attaching rod serves multiple functions: it acts as a structural connector, a tightening mechanism, and a alignment tool all in one component, eliminating the need for separate fasteners, aligning devices, and locking mechanisms for each joint
3Ease of operation
If traditional wood dowels and rod caps are used, then assembly is simple, but insufficient torque can be applied leading to weaker joints
Solution Approach 1:
The attaching rod system combines metal threading (for torque transmission) with plastic or rubber components (for grip and cushioning), enabling high torque application while maintaining ease of operation through the knurled surface design
Solution Approach 2:
The traditional friction-based wood dowel system is replaced with a threaded mechanical fastening system that converts rotational motion into linear clamping force, allowing precise control and application of high torque to create rigid, stable joints
4Productivity
If factory-manufactured sub-assemblies are used, then fewer parts need to be assembled, but the sub-assemblies occupy more volume requiring larger packaging
Solution Approach 1:
Smaller sub-assemblies (such as leg assemblies or armrests) are designed to nest within larger sub-assemblies (such as the seat or backrest), allowing multiple components to occupy the volume of a single component and significantly reducing overall packaging volume
Data Source
AI summary
A ready-to-assemble upholstered and non-upholstered chair consisting of factory assembled sub-assemblies reducing the number of overall parts and assembly hardware which decreases the packaged cubic measure allowing more units to be loaded into shipping containers and trailers, inventoried in warehouses and distribution centers and displayed in retail outlets thereby reducing transportation and handling costs, while simplifying and expediting the assembly process. The invention includes a seat box sub-assembly so constructed to allow a portion of the chair back leg sub-assembly to nest therein reducing the package profile and cubic measure, as well as a front leg sub-assembly. The front leg and back leg sub-assemblies are assembled utilizing a left and right tenoned side rail which inserts into mortises on the front and back leg assemblies. The leg sub-assemblies are secured with a metal bolt, threaded on each end, housed longitudinally within a routed channel running on the exterior face of each side rail. The bolt is secured by threading one end into the pre-installed knurled nut in the back leg sub-assembly and a hex socket T-nut and washer on the face of the front leg sub-assembly. The seat box sub-assembly is fitted over the front leg sub-assembly and the left and right side rails and secured on the underside with metal bolts. With the factory manufactured pre-assemblies resulting in fewer joints, the assembled chair is stronger eliminating potential racking. On upholstered chairs, the removable outer decorative back and seat cover are positioned over the chair back and chair seat and quickly Velcros into place. Chair covers can be removed for cleaning or retailers can sell additional covers in a variety of materials and designs without needing to stock additional chairs. Once assembled, the invention offers the distinction that no assembly hardware is visible, giving the chair a “factory made” look.