Foldable Chair Leg Reinforcement for Caster-Induced Weak Points
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Solution Overview
Problem
Conventional foldable chairs lack sufficient rigidity in their front legs, particularly at the bottom ends, which can lead to breakage when a heavy person sits on them, and the casters' design weakens the overall rigidity by only partially contacting the supporting surface.
Innovation Solution
The introduction of strengthening structures, including front and rear strengthening ribs inserted into hollow tubes and seated within inclined recesses of leg support elements, which extend beyond the reinforcing plates to uniformly reinforce the entire length of the front legs and casters, enhancing their rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcing plates are attached to inner sides of front legs, then rigidity of front legs is improved, but the bottom ends of reinforcing plates are spaced from leg support elements leaving weak portions
Solution Approach 1:
The strengthening structure is divided into multiple segments: upper strengthening portions that connect to reinforcing plates, middle strengthening portions that bridge the gap, and lower strengthening portions that connect to leg support elements. This segmentation allows comprehensive reinforcement of the entire front leg length without leaving weak portions.
Solution Approach 2:
The strengthening structure extends in multiple spatial dimensions: vertically along the length of the front leg, horizontally to connect opposing front legs, and diagonally to provide triangular bracing. This multi-dimensional approach ensures complete coverage and eliminates weak portions.
2Ease of operation
If casters are attached to bottom ends of front and rear legs, then mobility is improved, but total rigidity is weakened due to partial contact with supporting surface
Solution Approach 1:
The strengthening structure merges the reinforcing plates with the leg support elements through continuous strengthening portions, creating an integrated rigid assembly that compensates for the rigidity reduction caused by caster attachment. The combined structure acts as a unified load-bearing element.
Solution Approach 2:
The strengthening structure is pre-installed on the front legs before caster attachment, establishing a rigid framework that anticipates and compensates for the rigidity reduction that will occur when casters are mounted and only partially contact the supporting surface.
3Ease of manufacture
If reinforcing plates are spaced from leg support elements by predetermined distance, then ease of attachment is improved, but entire length of front leg is not reinforced
Solution Approach 1:
The middle strengthening portions act as intermediaries that bridge the gap between reinforcing plates and leg support elements. These intermediary elements maintain the ease of attachment benefits while ensuring continuous reinforcement coverage across the entire front leg length.
Data Source
AI summary
A foldable chair includes a chair body having two front legs, two rear legs connected pivotally to the two front legs; a seat disposed on the chair body; a backrest disposed on the chair body so as to be located above the seat; four leg support elements attached respectively to bottom ends of the two front legs and the two rear legs; four casters attached respectively to bottom sides of the leg support elements; two reinforcing plates attached respectively to inner sides of the two front legs and spaced at a predetermined distance from the leg support elements; and two strengthening rigs attached respectively to the two front legs and extending into the front and rear legs to an extent beyond bottom ends so as to be located between the reinforcing plates and the leg support elements, thereby strengthening the front and rear legs.