Rotating Scraper Tool for Polyethylene Conduit Surface Preparation
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Solution Overview
Problem
Existing methods for preparing polyethylene conduits for electrofusion in keyhole excavation operations are inefficient due to the need for significant excavation and the challenge of correcting out-of-roundness and oxidation on the conduit surface, which can lead to incomplete fusion and leakage.
Innovation Solution
A scraper tool assembly with a stationary frame and rotatable housing that includes a scraper tool with a cutting edge, which rotates around the conduit to remove a uniform layer of material and correct out-of-roundness, using split clamps to compress the conduit into a concentric configuration before scraping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional joining methods are used for metal conduits, then the conduits can be connected together, but machining, cutting, polishing, grinding, scraping, or cleaning operations are required which increase complexity and time
Solution Approach 1:
The invention changes the material parameter from metal to polyethylene, which fundamentally alters the joining method from mechanical (welding requiring machining) to thermal (electrofusion requiring surface preparation only). This parameter change eliminates the need for complex machining operations while maintaining joint reliability.
2Reliability
If polyethylene conduits are used instead of metal conduits, then corrosion resistance and durability are improved, but the conduit surface may become out-of-round and oxidized requiring complex preparation operations
Solution Approach 1:
The split clamp assembly performs preliminary action by compressing the conduit to restore roundness before the scraping operation. This preliminary correction of out-of-roundness ensures that the subsequent scraping blade can uniformly remove oxidation without encountering surface irregularities that would compromise electrofusion quality.
Solution Approach 2:
The device segments the surface preparation function into two distinct components: the split clamp assembly for correcting out-of-roundness and the scraping blade for removing oxidation. This segmentation allows each component to specialize in one aspect of surface preparation, improving overall effectiveness.
3Object-affected harmful factors
If keyhole excavation operations are performed, then disruption is minimized, but significant excavation is still required and conduit surface preparation becomes more difficult
Solution Approach 1:
The invention merges the clamp assembly and scraping blade into a single integrated tool that performs both functions at the conduit location. This combination eliminates the need for separate operations and equipment, making the entire surface preparation process achievable through the limited access provided by keyhole excavation.
Solution Approach 2:
The scraping blade is designed to be self-contained with its own drive mechanism and positioning system, allowing it to perform the scraping operation autonomously once positioned on the conduit. This self-service capability eliminates the need for external machining equipment that would be impossible to access through a keyhole excavation.
4Manufacturing precision
If a scraping tool rotates around the conduit to remove material, then a uniform layer can be removed, but the tool structure becomes complex requiring precise positioning and control
Solution Approach 1:
The scraping blade is positioned radially outward from the conduit surface at a constant distance, creating an equipotential cutting path around the conduit. This radial positioning ensures that the blade removes a uniform layer of material regardless of the conduit's initial out-of-round condition, as the blade follows the conduit's contour while maintaining constant radial offset.
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 tool effectively prepares the conduit surface for electrofusion by restoring roundness and removing oxidation, ensuring a leak-free fusion process through minimal excavation, reducing disruption and improving the reliability of underground pipe repairs.
Implementation Method 1
The scraper tool assembly includes a blade having a cutting edge extending longitudinally a preselected length on the conduit. An adjustment mechanism on the scraper tool assembly moves the cutting edge into and out of contact with the surface of the conduit to remove a uniform layer of material from the outer surface of the conduit.
Implementation Method 2
A split clamp assembly receives the conduit and compresses the conduit into a concentric configuration. The cylindrical housing members are connected to apply a radial compressive force on the first and second semicylindrical shaped portions of the pair of split clamps to compress the polyethylene conduit within the cylindrical opening to restore the surface of the conduit to a round configuration.
Data Source
AI summary
A stationary frame is positioned in surrounding relation with the surface of a polyethylene conduit to be prepared for scraping preliminary to performing electrofusion on the conduit by a keyhole operation in an excavated underground location. A scraper tool is mounted on the frame in a fixed longitudinal position to rotate around the surface of the conduit. A cutting blade of the scraping tool extends longitudinally a preselected length on the conduit into contact with the surface of the conduit. Rotation of the scraper tool carries the cutting blade completely around the surface of the conduit to remove a uniform layer of material from the surface of the conduit. Any out of roundness existing in the conduit is removed before the scraping operation is commenced. Uniform compression is applied by split clamps surrounding the conduit. Compression of the clamps restores the conduit to a concentric configuration preliminary to the electrofusion operation.