Coil Spring Core Layout With Unknotted End Turns to Prevent Leaning
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Solution Overview
Problem
Existing spring cores with unknotted end turns often experience misalignment and leaning issues due to differences in leg lengths, leading to compression problems during shipping and uneven sleep surfaces, and require more material to achieve similar resiliency, increasing costs.
Innovation Solution
A spring core design using identically configured coil springs with U-shaped end turns and high tensile strength wire, where every other coil spring in the outermost columns is rotated and flipped to secure to a single border wire, reducing material usage and preventing leaning under load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If coil springs with unknotted end turns and different leg lengths are used, then misalignment and leaning problems are corrected, but manufacturing complexity and material usage increase
Solution Approach 1:
The patent uses identically configured coil springs where each spring has the same U-shaped end turns with legs of equal length. This homogeneity simplifies manufacturing while the alternating orientation pattern (every other spring rotated) maintains proper alignment. The lacing wires connect corresponding legs of adjacent springs, creating a uniform repeating pattern that eliminates misalignment without requiring different spring configurations.
Solution Approach 2:
The patent introduces asymmetry in the arrangement pattern by rotating every other coil spring 180 degrees in the outermost columns. This asymmetric positioning of identical springs allows the shorter legs to face inward and longer legs to face outward, enabling proper connection to border wires while maintaining alignment with adjacent springs through the lacing wire pattern.
2Strength
If traditional helical lacing wires are used to connect end turns, then coil springs are secured together, but misalignment occurs causing rhombus shape and compression problems
Solution Approach 1:
The patent incorporates alignment features directly into the spring construction itself - the U-shaped end turns with specific leg orientations are pre-configured on each spring before assembly. This preliminary preparation ensures that when springs are assembled in alternating patterns, the legs automatically align properly with adjacent springs, preventing misalignment before the lacing process begins.
Solution Approach 2:
The lacing wires serve as intermediaries that connect corresponding legs of adjacent coil springs. By lacing corresponding legs together (shorter legs with shorter legs, longer legs with longer legs), the wires maintain proper spacing and alignment between springs, preventing the rhombus distortion that occurs when mismatched legs are connected.
3Strength
If more material is used in coil springs, then resiliency is improved, but cost and weight increase
Solution Approach 1:
The patent changes the tensile strength parameter of the wire used in coil springs to high tensile strength values (at least 290,000 psi). This parameter change allows the use of thinner wire diameters while maintaining the same spring resiliency and load-bearing capacity, thereby reducing material consumption and weight without sacrificing performance.
Data Source
Figure 1
Figure 2~5
Figure 2A~3B
AI summary
Disclosed herein is a bedding or seating product (10) having a spring core (12) comprising coil springs (26) having unknotted end turns (72, 74) made from high tensile strength wire. In each embodiment, the end turns (72, 74) of the coil springs (26) are generally U-shaped having one leg (76) longer than the other (78), the legs (76, 78) being joined by an arcuate connector (80). The springs (26) are oriented in the spring core (12) such that a long leg (76) of one end turn (72) abuts a short leg (78) of the adjacent end turn (72) prior to be wrapped in helical lacing wire (32). The high tensile wire enables the coil springs (26) to be manufactured using less wire than heretofore possible.