Binderless Mineral Wool Needle Felt Thermal Gradient
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Solution Overview
Problem
Conventional binderless mineral wool needle felts face challenges in achieving improved insulating properties while maintaining handling stability and avoiding electrical conductivity issues, particularly in high-temperature applications like electric ovens, due to the need for expensive and conductive aluminum linings.
Innovation Solution
The needling process is adapted to control the number of fibers arranged transversely across the thickness of the needle felt, decreasing from one side to the other to create a thermal insulation gradient, with increased needling density and varying fiber fineness, allowing for better insulating performance without compromising handling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the needle felt is needled with high density to improve handling stability, then the structural integrity is improved, but the insulating properties deteriorate due to increased thermal bridges
Solution Approach 1:
The patent applies local quality by creating zones with different needling densities within the needle felt. The first zone has a first needling density while the second zone has a second needling density that is lower than the first. This allows different regions to have different properties: the first zone provides structural integrity and handling stability, while the second zone maintains better insulating properties by having fewer thermal bridges.
2Strength
If aluminum lining is added to improve handling ability of low bulk density needle felts, then the mechanical properties are improved, but electrical conductivity issues arise interfering with control systems
Solution Approach 1:
The patent extracts or removes the aluminum lining component from the needle felt structure. Instead of using aluminum foil lining that provides mechanical strength but causes electrical conductivity problems, the invention achieves handling ability through controlled needling density zones within the mineral wool itself, eliminating the harmful electrical conductivity while maintaining the necessary mechanical properties.
3Stability of the object's composition
If the number of transverse fibers is increased to improve structural coherence, then the handling stability is improved, but the thermal insulation performance deteriorates
Solution Approach 1:
The patent applies local quality by spatially differentiating the density of transverse fibers through controlled needling. The first zone contains a higher density of transverse fibers formed by needling to provide structural coherence, while the second zone contains fewer transverse fibers to maintain thermal insulation performance. This local differentiation allows each zone to optimize for its specific function.
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 results in enhanced insulating properties with reduced energy consumption and improved handling ability, as demonstrated by increased temperature retention and reduced energy usage in tests, while avoiding the drawbacks of conventional linings.
Implementation Method 1
These needles comprise barbed hooks by which individual fibers are seized and taken along. The fibers pulled more deeply into the needle felt in this manner produce a fiber mingling of the fleece and arrange themselves predominantly transversely to the large areas.
Implementation Method 2
such needle felts are frequently used in systems or devices in which they are subject to substantial thermal strain. Heating systems, electric ovens or the like have to be mentioned as examples.
Data Source
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AI summary
The invention relates to a binderless needle felt (1) of mineral wool, comprising a plurality of fibers arranged predominantly in parallel to the large areas of the needle felt (1), and individual fibers at needling points which arranged predominantly transversely to the large areas by a needling process and by which the fibers of the needle felt (1) are felted such that the needle felt (1) is adapted to be handled as one element. This needle felt (1) is characterized in that the density of the needling points at a first large area (2) is at least 15 needling points/cm2, that the number of the fibers arranged transversely to the large areas decreases from the first large area (2) toward an opposite second large area (3) of the needle felt (1), and that a near-surface region at the second large area (3) is substantially free from fibers arranged transversely to the large areas. Thus, an improved needle felt is achieved which avoids the drawbacks in prior art and comprises an improved insulating effect with at least equivalent handling properties.