Figure-of-Eight Cable Manufacturing via Parallel Extrusion and Twisting
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Solution Overview
Problem
Existing processes for manufacturing figure-of-eight cables face issues such as sheath deformations and nonconcentric extrusions due to the structural weakness of the web connecting cable elements and the limitation of using a single extrusion technique for all cable elements, which affects the cable's structural integrity and concentricity.
Innovation Solution
A process where at least two transmission cores are fed and separately extruded with coaxial sheaths, then twisted together before cooling to form a figure-of-eight cable, allowing for the use of the most suitable extrusion technique for each element and minimizing deformations by merging the sheath materials before they harden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single extrusion technique is used for all cable elements, then the extrusion process is simplified, but the structural integrity and concentricity of the figure-of-eight cable deteriorates
Solution Approach 1:
The patent divides the cable into separate cable elements (first cable element with electrical conductors, second cable element with optical conductors and strength members) that are extruded independently using potentially different techniques, then joined together. This segmentation allows each element to be optimized separately while maintaining overall cable quality.
2Volume of moving object
If the web connecting cable elements is made thin to reduce cable size, then the cable compactness is improved, but the web structural strength deteriorates causing deformations
Solution Approach 1:
The patent changes the physical state parameter of the sheath material during the joining process. The sheath material is extruded in a softened state, allowing the web to be formed with minimal thickness while maintaining flexibility. As the material cools and hardens after extrusion, the web gains sufficient structural strength to prevent deformations despite its thin cross-section.
3Stability of the object's composition
If the sheath material is allowed to cool and harden before joining cable elements, then the individual cable elements gain structural stability, but the ability to merge sheath materials smoothly deteriorates
Solution Approach 1:
The patent performs the joining operation at an optimal moment during the cooling process. The cable elements are joined while the sheath material is still in a softened state, before complete hardening occurs. This timing allows the sheath materials to merge smoothly and form a continuous web, while still providing sufficient stability to maintain the figure-of-eight configuration during the joining process.
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 method ensures minimal deformations and allows for the use of different extrusion techniques for each cable element, resulting in a stable, concentric figure-of-eight cable with improved structural integrity and ease of splitting without ripcords.
Implementation Method 1
part of the sheath extruded around one core merges with part of the sheath extruded around the other core, thereby causing the cohesion of the two sheath materials
Implementation Method 2
After being extruded, the cable is cooled while it passes through a plurality of guide wheels
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3b
AI summary
It is disclosed a process and an apparatus (7) for manufacturing a figure of eight cable. An extrusion head (70) has separate extrusion dies (737a, 737b) extruding in parallel a first (12a) and second (12b) outer sheath around a first (11a) and second (11b) core, respectively, so as to provide two separate cable elements (10a, 10b) having respective longitudinal axes (X1,X2) laying in a first plane. While the outer sheaths (12a, 12b) are in a softened state, the cable elements are passed in parallel through a twisting die (77) which causes their longitudinal axes (X1,X2) to lay in a second plane forming a predetermined twisting angle with respect to the first plane. This twisting causes the outer sheaths (12a, 12b) to join together, thereby forming a figure of eight cable.