Remote Polishing Assembly for EDM Recast Layer Removal
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Solution Overview
Problem
Existing methods for removing recast layers from machined surfaces in remote and underwater environments, such as nuclear reactor repairs, are inadequate, as they either fail to remove the layer effectively or cannot impart necessary compressive stresses to strengthen the material.
Innovation Solution
A remotely operable bridge assembly with a spindle and polishing assembly that includes a rotatable polishing surface driven by motors, capable of applying compressive forces and rotating to remove recast layers and smooth surfaces, using a combination of pneumatic and hydraulic systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrical discharge machining is used to create precise holes in reactor components, then manufacturing precision is improved, but a recast layer is formed on the surface that requires additional treatment
Solution Approach 1:
The patent applies shot peening treatment to the recast layer formed by electrical discharge machining. The shot peening process impacts the recast layer with small particles, converting the harmful recast layer into a surface with compressive residual stresses that improve fatigue strength and material properties, thereby transforming the harmful byproduct into a beneficial surface treatment
2Manufacturing precision
If manual polishing methods are used to remove recast layers, then surface quality is improved, but the method cannot be applied in remote underwater environments
Solution Approach 1:
The patent replaces manual mechanical polishing with an automated shot peening system that can be remotely operated. The system uses a抛射 device to propel shot particles at the surface, eliminating the need for manual intervention while achieving effective recast layer removal and surface treatment in remote underwater environments
Solution Approach 2:
The patent employs pneumatic or hydraulic mechanisms to drive the shot peening process remotely. Compressed gas or hydraulic pressure is used to propel shot particles and operate the treatment device, enabling remote operation in underwater environments where manual polishing is impossible
3Strength
If compressive stresses are not applied to machined surfaces, then material strength is maintained, but the surface lacks durability and fatigue resistance
Solution Approach 1:
The patent uses shot peening to impart compressive residual stresses into the machined surface. This process transforms the surface layer by plastically deforming it through particle impact, creating a compressed state that enhances both surface durability and fatigue resistance while maintaining overall material strength
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
Effectively removes recast layers and imparts compressive stresses to create a durable surface finish, suitable for reactor components, even in inaccessible locations.
Implementation Method 1
a pneumatic slide, hydraulic motor, and/or stepper motor may be used to remotely provide biasing and various rotations
Implementation Method 2
a pneumatic slide, hydraulic motor, and/or stepper motor may be used to remotely provide biasing and various rotations
Implementation Method 3
The polisher may include a round filament brush. The spindle can rotate about another axis to move the polisher around a partial or entire perimeter of the surface to be treated
Data Source
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AI summary
Systems remotely polish and compress surfaces for working, including surfaces created through electrical discharge machining. A bridge may secure about the surface and carry a spindle that rotatably extends downward and carries a polishing assembly. The polishing assembly can push against the surface while polishing the same with larger amounts of force. The polisher can be moved about a perimeter of the surface and vertically. Systems may be remotely operated with a pneumatic slide, hydraulic motor, and/or stepper motor. Spotfaces formed from electrical discharge machining, including those in nuclear facilities and deep underwater, may have recast layers removed with such systems without manual or direct operator interface.