Laser-Welded Optical Cable Jacket for Shrinkage Control
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Solution Overview
Problem
The challenge in manufacturing optical cables lies in managing thermal shrinkage of the polymer jacket during and after the extrusion process, which can result in excessive fiber length and optical bending losses, especially as manufacturing speeds increase.
Innovation Solution
The process involves pre-extruding a thermoplastic sheet around optical fibers, followed by annealing to relieve internal stress, and then welding the sheet's edges using a laser to form a seam that maintains the jacket's configuration and provides easy access to the fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the extrusion speed is increased to improve productivity, then the thermal shrinkage of the polymer jacket becomes more severe, resulting in excessive fiber length and optical bending losses
Solution Approach 1:
The cable jacket is formed by wrapping a pre-extruded flat sheet around the fiber assembly and welding the edges, rather than extruding a tubular jacket directly. This segmentation of the extrusion process into sheet formation followed by wrapping and welding allows better control of thermal shrinkage and fiber length.
Solution Approach 2:
The polymer sheet is extruded and cooled to a stable temperature before being wrapped around the fiber assembly. This preliminary action ensures that the sheet has minimal thermal shrinkage potential before contact with the fibers, preventing excessive fiber length even at high assembly speeds.
2Strength
If a welded seam is formed by melting thermoplastic material to join opposing edges, then the jacket strength is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The welding process uses a laser beam to melt and join the thermoplastic edges, replacing traditional mechanical fastening methods. This provides strong joints while maintaining a relatively simple process setup.
Solution Approach 2:
The thermoplastic material at the edges is heated to melt and then cooled to solidify, creating a strong welded seam. This phase transition approach ensures adequate molecular entanglement for desired joint strength without complex mechanical systems.
3Manufacturing precision
If the extrusion and assembly processes are separated to manage thermal shrinkage, then the fiber length control is improved, but the manufacturing time increases
Solution Approach 1:
The polymer sheet is extruded and allowed to cool to a stable temperature before being wrapped around the fiber assembly. This preliminary cooling action eliminates thermal shrinkage issues during assembly, enabling high-speed manufacturing with precise fiber length control.
Solution Approach 2:
The separated extrusion and assembly processes are performed continuously without interruption. The pre-cooled sheet is immediately wrapped and welded in sequence, maintaining high throughput while achieving precise fiber length control through the temperature separation.
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 allows for higher throughput in cable assembly, reduces shrinkage, and enhances the strength of the cable jacket while enabling easy opening features without additional structures, thus addressing the issues of excessive fiber length and optical bending losses.
Implementation Method 1
The welding of the profile would be accomplished by heating just the joining region of the profile with a laser
Implementation Method 2
The welded seam is formed from portions of the wrapped sheet of thermoplastic material at the opposing longitudinal edges melted together
Implementation Method 3
The finished polymer profiles may first be extruded and then annealed to relieve and internal stress within the profile
Data Source
AI summary
An optical cable and method for forming an optical cable is provided. The cable includes a cable jacket including an inner surface defining a channel and an outer surface and also includes a plurality of optical fibers located within the channel. The cable includes a seam within the cable jacket that couples together opposing longitudinal edges of a wrapped thermoplastic sheet which forms the cable jacket and maintains the cable jacket in the wrapped configuration around the plurality of optical fibers. The method includes forming an outer cable jacket by wrapping a sheet of thermoplastic material around a plurality of optical core elements. The method includes melting together portions of thermoplastic material of opposing longitudinal edges of the wrapped sheet such that a seam is formed holding the sheet of thermoplastic material in the wrapped configuration around the core elements.