Microduct Sheath Cooling Rate Control to Prevent Thermal Welding
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Solution Overview
Problem
The unintentional welding of the outer sheath to the microducts during the manufacturing of bundled microducts within an outer sheath is a recurring issue, caused by unbalanced cooling leading to shrinkage and permanent bonding.
Innovation Solution
The introduction of an air gap between the die and a cooling tank, along with a cooling tank divided into sections, allows for extended air cooling of the sheath, reducing the cooling rate and preventing unwanted welding by ensuring the inner surface of the sheath hardens before coming into contact with the microducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cooling water temperature is increased to reduce the temperature difference and prevent welding, then the welding issue is resolved, but the production rate slows down because the extruded sheath material takes longer to cool and harden
Solution Approach 1:
The cooling tank is divided into multiple sections with different cooling intensities. The first section uses cooling water at a higher temperature to prevent welding, while subsequent sections use cooler water to achieve rapid hardening and maintain high production rates. This segmentation allows different cooling zones to perform different functions sequentially.
Solution Approach 2:
Different sections of the cooling tank provide different cooling conditions tailored to specific needs. The first section provides gentle cooling to prevent welding where the temperature difference is most critical, while later sections provide aggressive cooling to harden the sheath quickly for production efficiency.
2Productivity
If the cooling rate is increased to maintain high production speed, then productivity is improved, but the inner surface of the sheath remains molten too long causing welding to microducts
Solution Approach 1:
The cooling process is segmented into stages: initial gentle cooling in the first section prevents welding, followed by rapid cooling in subsequent sections that hardens the sheath quickly. This staged approach allows the inner surface to cool gradually enough to prevent welding while still achieving high production speeds.
Solution Approach 2:
The first cooling section performs the preliminary action of preventing welding by using warmer water before the sheath enters the rapid cooling sections. This preliminary gentle cooling prevents the temperature difference that causes welding, while subsequent sections complete the hardening process quickly.
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 inhibits thermal welding between the sheath and microducts while maintaining high production speeds, achieving a production speed increase of up to 70% without any welding in the resulting product.
Implementation Method 1
an air gap between the die and a cooling tank... a first section of the cooling tank contains only air at a temperature lower than the temperature of the air gap... allows the sheath to be air cooled for an extended time period
Implementation Method 2
the cause of the unwanted welding is from shrinkage of the sheath polymer material due to unbalanced cooling of the inside surface versus outside surface of the sheathing material
Data Source
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AI summary
An apparatus for making a product comprising a plurality of microducts bundled within a protective outer sheath, wherein the apparatus functions to inhibit thermal welding of the sheath and the microducts, and a corresponding method of making the bundled microducts.