Three-Strand Hammered Draw Tape for Cable Installation
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Solution Overview
Problem
Existing draw tapes face difficulties in inserting cables into tubular sheaths with small radii or obstacles, requiring excessive pushing force and often leading to installation challenges and material weaknesses, especially in masonry-embedded sheaths.
Innovation Solution
A draw tape with a flexible helical multifilament rope, externally coated with lubricating materials, featuring a reduced number of strands and a hammered assembly to enhance stiffness and flexibility, allowing for efficient pushing and pulling forces while minimizing friction and material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of strands in the rope is increased to enhance strength, then the pushing and pulling force transmission is improved, but the friction with the tube walls increases and flexibility is reduced
Solution Approach 1:
The patent changes the structural parameters of the rope by reducing the number of strands from the conventional high number to exactly three strands. This parameter change optimizes the balance between strength and flexibility, allowing the draw tape to transmit sufficient pushing and pulling forces while maintaining the ability to navigate bends and obstacles in cable ducts with reduced friction.
2Ease of operation
If the sheath section is increased to facilitate cable insertion, then the passage of cables is improved, but the masonry structure is weakened and installation complexity increases
Solution Approach 1:
The invention changes the physical parameters of the draw tape by using a three-strand helical construction with lubricating coating, which reduces the friction coefficient between the draw tape and the sheath walls. This allows cables to be inserted into smaller-diameter sheaths without requiring excessive force, thereby maintaining masonry structure integrity while facilitating cable installation.
3Force
If the rope diameter is increased to enhance force transmission, then the pushing and pulling capability is improved, but the flexibility and ability to pass through narrow passages is reduced
Solution Approach 1:
The patent employs a composite structure consisting of three strands made from high-strength materials (such as steel or synthetic fibers) helically wound together and coated with a lubricating material. This composite construction provides high force transmission capability through the strong core strands while the lubricating coating reduces friction, and the helical geometry with only three strands maintains flexibility for navigating narrow passages and bends.
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 draw tape effectively transmits higher forces with reduced friction and material usage, facilitating easier cable installation and maintaining smaller sheath sections, thus simplifying the installation process and reducing material costs.
Implementation Method 1
The small number of strands, particularly the number of three filaments or strands guarantees many advantages. Several laboratory tests have shown how the reduced number of strands results in a smaller number of contact points of the rope with the elements it is in contact with. Thus the contact points, or better the helical areas in contact with the rope are limited as regards extension, and therefore generate a smaller friction force.
Data Source
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AI summary
Draw tape for cables comprising an elongated flexible element composed of a helical multifilament rope (1) composed of three filaments or strands helically wound about a common longitudinal axis. According to a further characteristic said rope is hammered. Still according to an improvement said rope is externally covered by a jacket (2).