Rectangular Border Wire for Lower-Cost Spring Cores
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Solution Overview
Problem
The high cost of manufacturing spring cores for mattresses is primarily due to the expensive steel used in coil springs, with standard gauge wire requiring more material and having lower tensile strength than high tensile strength wire, leading to increased material usage and production costs.
Innovation Solution
Shaping the border wire from a smaller diameter, seven-gauge wire into a rectangular cross-section maintains beam strength while reducing material usage, allowing for cost savings by using less steel without compromising the integrity of the spring core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If standard gauge wire is used for border wire, then material usage is higher, but beam strength is maintained
Solution Approach 1:
The patent changes the cross-sectional geometry parameter of the border wire from circular to rectangular. This parameter change allows the use of smaller diameter wire (seven-gauge instead of six-gauge) while maintaining the same beam strength through the rectangular cross-section shape, thereby reducing material usage and cost.
2Quantity of substance
If high tensile strength wire is used for coil springs, then material cost is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent changes the material parameter by switching from standard tensile strength wire (220,000-260,000 psi) to high tensile strength wire (greater than 265,000 psi). This allows coil springs to be made with fewer turns and less material while maintaining the same resiliency, reducing overall material cost despite the higher unit cost of the wire.
Data Source
AI summary
A bedding or seating product comprising a spring core including upper and lower border wires. Each of the border wires is generally rectangular in cross-section to reduce wire costs without compromising beam strength of the border wire. Each row of springs of the spring core may be made of a single piece of wire. The rows of springs may be arranged in side-by-side rows and columns and be connected with each other by helical lacing wires.