Molded Plastic Furniture Foot With Ribbed Anchor Retention
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Solution Overview
Problem
Conventional feet for injection molded plastic furniture lack reliability, grip strength, and ease of installation, often leading to premature detachment and increased manufacturing costs due to the use of semi-flexible materials and complex assembly processes.
Innovation Solution
A foot design featuring a hard plastic anchor and soft plastic pad, co-extruded for a chemical bond, with ribs that deform to create a mechanical interlock within the furniture cavity, allowing for easy insertion and secure retention without requiring excessive force or specialized tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If semi-flexible materials are used for conventional feet, then the feet can be easily inserted into the cavity, but the grip strength decreases over time due to compression set
Solution Approach 1:
The patent changes the material parameter by using a softer, more flexible material (lower durometer) for the foot body compared to conventional semi-flexible materials. This softer material maintains its flexibility without taking compression set as quickly, thereby retaining grip strength over time while still allowing easy insertion into the cavity
Solution Approach 2:
The patent employs a composite structure combining a flexible foot body made of softer material with a hard anchor portion. This composite design allows the foot body to remain compliant for easy insertion and good surface grip, while the hard anchor provides stable, long-term retention in the cavity without deforming
2Reliability
If softer, lower-durometer materials are used for feet, then frictional grip on substrates is improved, but the materials take compression set more quickly
Solution Approach 1:
The patent divides the foot into two distinct segments: a softer foot body for frictional grip and a harder anchor portion for structural durability. The foot body uses softer, lower-durometer material to maximize frictional grip on substrates, while the anchor is made of harder material that resists compression set and deformation, thus solving the contradiction between grip and durability
Solution Approach 2:
The patent uses composite materials with different durometer ratings for different functional portions of the foot. The softer material provides enhanced frictional grip, while the harder anchor material maintains structural integrity and resists compression over time, achieving both improved grip and sustained durability
3Reliability
If the anchor portion is made wider than the cavity for friction fit, then retention is improved, but insertion difficulty increases
Solution Approach 1:
The patent changes the dimensional parameters of the anchor portion to match the cavity dimensions more closely, eliminating the need for a significantly wider anchor. Combined with the use of a softer foot body material, this allows the foot to be inserted more easily while still achieving adequate retention through the interlocking mechanism and friction
Solution Approach 2:
The patent replaces the conventional friction-fit mechanical retention system with a combination of interlocking geometry (ribs fitting into cavity features) and material properties. This substitution allows for better retention without requiring the anchor to be significantly wider than the cavity, thereby facilitating easier insertion
4Ease of manufacture
If conventional friction fit method is used, then assembly is simple, but grip strength is insufficient and feet may detach
Solution Approach 1:
The patent uses composite materials with a hard anchor portion and softer foot body to achieve both simple assembly and strong grip. The hard anchor provides structural integrity for reliable retention, while the softer foot body maintains frictional grip on surfaces. The combination allows the foot to be inserted by hand or with minimal force while achieving superior retention and grip strength
Solution Approach 2:
The patent incorporates preliminary design features in the anchor portion geometry and material selection that enable the foot to achieve adequate retention and grip strength before final installation. The interlocking geometry and material properties are pre-configured to provide reliable attachment, eliminating the need for complex assembly processes or post-installation adjustments
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 provides a cost-effective, reliable, and easy-to-install foot system that maintains grip strength over time, reducing the risk of detachment and improving the stability and performance of injection molded furniture, as demonstrated by increased pull force resistance and compliance with ASTM standards for outdoor furniture.
Implementation Method 1
with ribs that deform to create a mechanical interlock within the furniture cavity
Implementation Method 2
co-extruded for a chemical bond
Data Source
AI summary
A foot for molded plastic furniture has a pad portion made of a first plastic or thermoplastic rubber and an anchor portion made of a second harder plastic or metal. The anchor has a base with a substantially flat surface that is bonded to a substantially flat top surface of the pad. Preferably the anchor portion and pad portion are co-extruded. A projection having at least one rib extends from the base of the anchor and is inserted into a cavity in a furniture leg creating a reliable mechanical fit which resists removal of the foot from the leg.