Fire-Resistant Cable Opposing Tape Wrapping
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Solution Overview
Problem
Existing fire-resistant cables face issues with inhomogeneous surfaces and inconsistent performance during flexing due to large overlaps in mica wrappings, which also slow down production, and low overlap designs are prone to errors and rapid failure during fire exposure.
Innovation Solution
A fire-resistant cable design featuring tightly wrapped tape turns of mica tape in opposing directions with controlled overlaps between 5% and 20% to reduce roughness and ensure reliable performance, combined with a method of wrapping both fire-protection layers on a single machine for efficient manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large overlap (50% or more) is used in mica tape wrapping to maintain protection during flexing, then reliability is improved, but production speed deteriorates and surface homogeneity worsens
Solution Approach 1:
The patent changes the wrapping parameters by reducing the overlap from conventional 50% or more to a specific range of 10-30mm, and introduces alternating wrapping directions (first layer in one direction, second layer in opposite direction) to achieve both adequate protection and improved production efficiency
Solution Approach 2:
The patent applies asymmetry by wrapping the first fire-protection layer and second fire-protection layer in opposing directions relative to the cable longitudinal axis, creating a balanced structure that reduces surface roughness while maintaining protection during flexing
2Reliability
If large overlap (50% or more) is used in mica tape wrapping to maintain protection during flexing, then reliability is improved, but surface homogeneity worsens due to wrinkles
Solution Approach 1:
The patent changes the overlap parameter from conventional 50% or more to a controlled range of 10-30mm, and introduces alternating wrapping directions to achieve a smoother, more homogeneous surface while maintaining adequate protection during flexing
Solution Approach 2:
By wrapping layers in opposing directions, the patent creates a balanced structure where the asymmetry of individual wraps is compensated, resulting in a more homogeneous overall surface appearance
3Productivity
If low overlap (less than 5%) is used in tape wrapping to reduce material cost, then productivity is improved, but reliability deteriorates due to gap opening during bending
Solution Approach 1:
The patent optimizes the overlap parameter to a specific range of 10-30mm (neither too large nor too small), and introduces alternating wrapping directions to ensure gaps remain closed during bending while maintaining fast production speed
Solution Approach 2:
The alternating wrapping directions create a interlocking effect that prevents gap opening during cable bending, ensuring reliability even with reduced overlap percentages
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
The invention relates to a fire-resistant cable (10) with a cable longitudinal axis (LA), comprising a conductor (1), a first fire-protection layer (3A) formed by tightly wrapped tape turns (3A1, 3A2, 3A3,...) around said conductor (1) and enclosing said conductor (1), a second fire-protection layer (3B) formed by tightly wrapped tape turns (3B1, 3B2, 3B3,...) around said first fire-protection tape (3A) and enclosing said first fire-protection tape (3A) a conductor insulation layer (2) enclosing said second fire-protection layer (3B), and an outer jacket (4) surrounding said conductor insulation layer (3B). According to the invention, the first fire-protection layer (3A) and the second fire-protection layer (3B) are formed from tape turns (3A1, 3A2, 3A3,...; 3B1, 3B2, 3B3, ...) wrapped in opposing directions with respect to the cable longitudinal axis (LA). The invention also concerns a method for producing a fire-resistant cable.