Office Chair Column Socket Structure With Molded Metal-Plastic Joint
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Solution Overview
Problem
Existing office chair connecting structures between the column and seating portion are costly due to material and manufacturing processes, and lack sufficient structural integrity for intensive use, requiring expensive self-lubricating sockets and restrictive shape limitations.
Innovation Solution
A connecting structure formed by injection molding plastic with glass fiber reinforcement and a pressed sheet metal frusto-conical socket, eliminating the need for additional components and providing structural reinforcement through internal ribs and flanges, allowing direct load transfer and simplified orientation during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If die-casting aluminum is used for box support, then structural strength is improved, but manufacturing cost increases due to material cost, die-casting operations, and metal finishing operations
Solution Approach 1:
The patent uses a composite structure combining plastic material for the box support with an inserted metal frusto-conical socket. This allows the main body to be made from cost-effective plastic while the critical load-bearing connection point uses metal, achieving both cost reduction and structural integrity.
Solution Approach 2:
The box support is divided into separate components: the main plastic body and the metal frusto-conical socket inserted into it. This segmentation allows each component to be manufactured independently using optimal processes (injection molding for plastic, pressing for metal) and then assembled, reducing overall manufacturing cost and complexity.
2Reliability
If self-lubricating sockets are used to prevent seizure, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the surface parameters of the frusto-conical socket by providing external transverse ribs that increase surface area and improve grip. This geometric modification reduces friction and prevents seizure without requiring expensive self-lubricating materials, achieving reliability through form rather than material composition.
3Strength
If traditional metal structures with conical insertion-fitting are used, then connection strength is improved, but device complexity increases due to multiple components and assembly steps
Solution Approach 1:
The patent merges the box support body and the frusto-conical socket into a single integrated component where the metal socket is inserted and fixed within the plastic body. This combination reduces the number of separate parts and simplifies assembly while maintaining the strength benefits of the conical insertion-fitting connection.
4Ease of manufacture
If plastic material is used for box support, then manufacturing cost is reduced, but structural strength decreases
Solution Approach 1:
The patent creates a composite structure where plastic material forms the main box support body (providing cost-effectiveness) while a metal frusto-conical socket is inserted into it (providing structural strength). This composite approach allows the inexpensive plastic to be used where full strength is not required, while metal is concentrated only at the critical connection point.
Solution Approach 2:
The patent applies local quality by using metal material specifically at the frusto-conical socket location where high strength is needed for the column connection, while the rest of the box support body uses plastic material. This localized material selection optimizes both cost and strength by placing expensive material only where absolutely necessary.
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 solution reduces production costs, enhances structural integrity, and simplifies the manufacturing process while maintaining the necessary strength to pass regulatory tests, offering a cost-effective and versatile design.
Implementation Method 1
a first box support 4 is formed by injection molding plastic material
Implementation Method 2
the connection between the column and the structure is obtained by a male conical part provided in the head of the column and insertion-fitted into a corresponding female conical part obtained in the structure
Data Source
AI summary
A method of forming a connecting structure between column and seating portion of an office chair includes the steps of forming a frusto-conical portion having a flange by cold-pressing a portion of sheet metal, inserting the flanged portion into a mold reproducing the shape of the structure, injecting plastic material into the mold and incorporating the flanged portion of the frusto-conical portion into the plastic material.