Polymeric Cable Liner With Transverse Cavities for Lubricant Retention
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Solution Overview
Problem
Current control cable liners face issues with sliding resistance and durability due to attrition and lubricant migration, leading to increased friction and reduced service life, especially under high load and frequency conditions.
Innovation Solution
A polymeric control cable liner with transverse annular cavities on its internal surface to retain lubricant and reduce contact area, combined with a non-linear wall thickness for minimized sliding resistance, fabricated using a specially designed extrusion die-head that ensures consistent cavity formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a smooth internal surface is used to minimize sliding resistance, then sliding resistance is reduced, but lubricant retention is poor leading to increased wear over time
Solution Approach 1:
The liner combines smooth regions (for low friction) with cavitated regions (for lubricant retention) in different locations. The internal surface has transverse cavities that create local zones of high lubricant concentration while maintaining smooth contact areas, resolving the contradiction between sliding resistance and lubricant retention.
Solution Approach 2:
The liner incorporates transverse cavities (porous structure) within the wall thickness that trap and retain lubricant. This porous-like structure allows the liner to hold lubricant reserves that can be released during operation, maintaining durability without compromising smooth operation.
2Ease of operation
If lubricant is applied to reduce friction, then sliding resistance is reduced, but lubricant migrates to cable ends leading to loss of lubricity
Solution Approach 1:
The cavities are pre-filled with lubricant during the extrusion process, creating a lubricant reservoir before the cable is assembled. This preliminary action ensures lubricant is available at the correct location from the start, preventing migration issues.
Solution Approach 2:
The cavitated structure acts as an intermediary between the liner material and the cable surface, providing a controlled release mechanism for lubricant. Instead of direct application that allows migration, the cavities mediate lubricant delivery to maintain consistent lubrication.
3Reliability
If the liner wall thickness is increased to improve durability, then wear resistance is improved, but sliding resistance increases due to greater contact area
Solution Approach 1:
The liner uses variable wall thickness with cavitated regions that create local thickness variations. These variations reduce the effective contact area with the cable while maintaining overall structural durability, resolving the contradiction between durability and sliding resistance.
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 significantly reduces sliding resistance and enhances the service life of control cables by maintaining lubricant retention and minimizing wear, while allowing for customizable properties through co-extruded layers for specific applications.
Implementation Method 1
a plurality of separated, substantially transverse, annular cavities projects outwardly from the internal surface... the cavities being configured for lubricant retention
Implementation Method 2
A polymeric liner (illustrated at A in Figure 1) is designed to minimize friction and promote smooth operation of the actuating cable
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A new type of polymeric tubular control cable liner formed by extrusion whereby transverse lubricant retention cavities A project outwardly from its internal bearing surface with a force transmitting core and which thereby facilitate improved lubrication and a reduction in sliding resistance.