Heating Element Resistivity Uniformity via Asymmetric Fiber Cutting
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Solution Overview
Problem
Conventional sheet-shaped heaters with metal fibers exhibit non-uniform electrical conductivity due to fiber orientation during manufacturing, leading to non-uniform heat generation when current is applied.
Innovation Solution
A belt-shaped heater wire configuration where short metal fibers are partially bonded, with resistivity ratios measured along different directions within specific ranges to inhibit non-uniform electrical conductivity and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal fibers are oriented in the longitudinal direction during sheetmaking, then the manufacturing process is simplified, but non-uniform electrical conductivity occurs leading to non-uniform heat generation
Solution Approach 1:
The patent applies asymmetry by cutting the metal fiber sheet at an angle (30-60 degrees) relative to the longitudinal direction, creating a quadrangular shape rather than a standard rectangle. This asymmetric cutting approach disrupts the fiber orientation pattern established during sheetmaking, ensuring that fibers are not aligned uniformly in the longitudinal direction. As a result, the electrical conductivity becomes more uniform across different directions, preventing non-uniform heat generation while maintaining the simplicity of the sheetmaking process itself.
2Productivity
If metal fibers are oriented in the conveyance direction, then the sheetmaking process is straightforward, but heat generation becomes non-uniform when current is applied
Solution Approach 1:
The patent employs asymmetric cutting at 30-60 degrees to the longitudinal direction, which disrupts the fiber orientation created during efficient sheetmaking. This angular cutting ensures that no single direction of fiber alignment dominates, thereby maintaining high productivity during sheetmaking while ensuring uniform heat generation throughout the heating element when current is applied.
Solution Approach 2:
The patent applies local quality by creating different fiber orientation characteristics in different regions of the heating element through the angled cutting approach. The quadrangular shape with sides at specific angles (30-60 degrees and 80-100 degrees) ensures that local fiber arrangements vary appropriately, optimizing heat generation uniformity in each region while maintaining overall manufacturing efficiency.
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 effectively prevents non-uniform heat generation, ensuring consistent heating across the heating element, which is crucial for applications like heating molds or extruders.
Implementation Method 1
when a current is applied to the high heat-transfer sheet, heat generation is non-uniform on a part of the sheet
Implementation Method 2
a magnitude of a ratio of resistivity of the heating element measured along a second direction orthogonal to a longitudinal direction of the heating element, to resistivity of the heating element measured along a first direction which is the longitudinal direction of the heating element
Data Source
AI summary
In a heating element (46) constituting a belt-shaped heater wire, the heater wire is configured such that short metal fibers are at least partially bonded to each other. A magnitude of a ratio of resistivity of the heating element (46) measured along a second direction orthogonal to a longitudinal direction of the heating element (46), to resistivity of the heating element (46) measured along a first direction which is the longitudinal direction of the heating element (46), is within a range of 0.9 to 1.1, and a magnitude of a ratio of the resistivity of the heating element (46) measured along the first direction, to resistivity of the heating element (46) measured along a third direction making an angle of 45° with respect to the first direction at a surface of the heating element (46), is not greater than 0.8 or not less than 1.2.