Nuclear Pipe Repair Device Helical Cutting Mechanism

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Solution Overview

Problem

Current repair methods for welded parts between nozzles and pipes in nuclear reactors are inefficient, requiring multiple devices and extensive aftertreatment due to non-uniform shapes and alignment issues.

Innovation Solution

A repair device with a casing, slide shaft, turntable, cutting mechanism, and advancing/retracting mechanism that allows the cutting tool to helically move along the inner pipe surface, combined with a buff mechanism, enabling precise cutting and buffing without separate device installations, and a clamp mechanism for self-standing operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple separate devices are used for cutting and buffing operations, then each operation can be performed with dedicated equipment, but the complexity of the repair process increases and more devices need to be transported and installed

Engineering Contradiction:
Improvecutting accuracyVSAvoidnumber of separate devices
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the cutting mechanism and buff mechanism into a single integrated repair device. The cutting mechanism includes a cutting tool for cutting operations, while the buff mechanism includes a buff for surface finishing. Both mechanisms are mounted on the same turn table and share common support structures, allowing them to be transported and installed as one unit rather than separate devices.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The repair device is designed with multi-functionality, where a single device can perform both cutting and buffing operations. The turn table can rotate to position either the cutting mechanism or the buff mechanism for their respective operations, making the device universal for multiple repair tasks that previously required separate specialized equipment.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Manufacturing precision

If separate cutting and buffing devices are used, then each operation can be optimized independently, but the time required for transporting and installing multiple devices increases

Engineering Contradiction:
Improvecutting precisionVSAvoidtransport and installation time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The cutting mechanism and buff mechanism are merged into a single integrated device that can be transported and installed as one unit. This eliminates the need to separately transport and install multiple devices, reducing the time loss associated with device setup while maintaining the precision capabilities of both cutting and buffing operations.

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If the cutting tool follows a simple rotational path, then the mechanism is simpler, but it cannot accurately follow the inner peripheral shape of the pipe

Engineering Contradiction:
Improvetrajectory control mechanismVSAvoidcutting accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The repair device employs dynamic trajectory control where the cutting tool's path is not fixed but can be adjusted to follow the inner peripheral shape of the pipe. The turn table rotates while the cutting mechanism can radially displace, creating a dynamic helical motion pattern that adapts to the pipe's geometry. This dynamic adjustment allows the cutting tool to accurately follow non-circular pipe profiles.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cutting tool motion is extended from simple two-dimensional rotation to three-dimensional helical motion by adding radial displacement capability. The cutting mechanism can move radially inward and outward while the turn table rotates, creating a helical trajectory that follows the pipe's inner peripheral shape. This dimensional addition enables accurate cutting of pipes with varying profiles.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Ease of manufacture

If multiple devices are used for repair operations, then each device can be optimized for its specific function, but the overall repair process becomes more complex and less efficient

Engineering Contradiction:
Improvedevice specializationVSAvoidrepair efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The cutting mechanism and buff mechanism are combined in a single integrated device that can perform both operations sequentially on the same pipe. The turn table rotates to position the appropriate mechanism for each operation, allowing the repair process to be completed with one device rather than requiring transportation and installation of multiple separate devices, thereby improving repair efficiency.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2524753B1Repair device and repair method
Publication Date: 2016.11.02 MITSUBISHI HEAVY IND LTD
  • EP2524753B1 patent drawingFigure 1
  • EP2524753B1 patent drawingFigure 2
  • EP2524753B1 patent drawingFigure 3~4

AI summary

This repair device includes a casing, a slide shaft slidably arranged with respect to the casing, a turn table rotatably arranged with respect to the slide shaft, a cutting mechanism installed on the turn table and including a cutting tool, and an advancing and retracting mechanism that displaces a radius of rotation of the cutting mechanism with respect to rotations of the turn table forward and backward. In a state where the casing is centered and positioned with respect to the pipe, the turn table is rotationally displaced while the slide shaft slides in an axial direction, and the advancing and retracting mechanism displaces the cutting mechanism forward and backward. Accordingly, the cutting tool helically turns along an inner peripheral shape of the pipe to cut an inner periphery of the pipe.