Pocketed Spring Unit Welding to Eliminate Adhesive and Reduce Cost
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Solution Overview
Problem
The extensive use of glue in manufacturing pocketed spring units increases production costs and hinders recycling due to the presence of adhesive in the product.
Innovation Solution
A method and apparatus for forming pocketed spring units using welding instead of glue, where sheets of material are welded to the ends of coil springs using heat or electric current, allowing for the use of springs of different shapes and geometries without the need for center-to-center adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glue is used to attach strings of pocketed springs to form a unit, then the strings can be held together to form the unit, but the manufacturing cost increases and recycling becomes difficult
Solution Approach 1:
The patent replaces the chemical bonding system (adhesive/glue) with a mechanical bonding system (welding). The welding device applies heat and pressure to fuse the fabric sheets directly to the spring coils, eliminating the need for adhesive materials. This substitution reduces manufacturing costs by removing adhesive material costs and simplifies recycling by eliminating chemical contaminants from the product structure.
2Strength
If glue is used to attach strings of pocketed springs to form a unit, then the strings can be held together to form the unit, but the presence of adhesive hinders recycling
Solution Approach 1:
The patent replaces chemical bonding (adhesive) with mechanical bonding (welding). The welding process fuses the fabric to the spring coils through heat and pressure, creating a strong bond without introducing chemical substances. This eliminates harmful adhesive residues that would contaminate recycling streams, making the pocketed spring unit easier to recycle while maintaining the required bonding strength.
3Ease of manufacture
If welding is used to attach sheets to springs, then adhesive is eliminated and recycling is facilitated, but new manufacturing equipment and processes are required
Solution Approach 1:
The patent extracts the welding functionality from conventional textile joining methods. By introducing a dedicated welding device with heating elements and pressure application mechanisms, the system separates the bonding function from traditional adhesive application. While this adds equipment complexity, it eliminates the need for adhesive materials and simplifies recycling, representing a strategic trade-off that benefits environmental sustainability.
4Manufacturing precision
If springs are compressed axially prior to welding, then welding quality is improved, but additional compression equipment and process steps are required
Solution Approach 1:
The patent applies preliminary compression to the springs before the welding operation. By compressing the springs axially prior to welding, the coils are brought into closer proximity and the fabric sheets are positioned more uniformly against the spring ends. This preliminary action improves welding quality by ensuring consistent contact and heat distribution during the welding process, justifying the addition of compression capability to the manufacturing system.
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
This approach reduces manufacturing costs and facilitates recycling by eliminating adhesive, enabling the use of varied spring shapes and geometries while maintaining structural integrity through end-to-end welding.
Implementation Method 1
welding the material by the application of heat
Implementation Method 2
welding the material by the application of heat
Implementation Method 3
the springs may be of conductive metal and where an electric current is used to weld the material the springs may be arranged to conduct the applied welding current
Data Source
AI summary
A method of forming a pocketed spring unit for an upholstered article comprises taking successive strings of pocketed springs and welding at least one sheet of material to at least a first end of the pocketed springs. Anvils 46 are moved from a non-operative position to an operative position, in which they are located between adjacent pockets at upper and lower ends of the springs. This embodiment makes use of the surplus material that is formed at the ends of the pockets in the form of flaps or “ears” of material. These flaps protrude upwardly initially, and then become folded flat as the spring unit advances between the rolls 48 of material.The external anvils are then made to apply heat and pressure to the material flaps trapped between them and the internal anvils at the sides of the pockets, between the springs to weld them to the material from the rolls 48.