Inspection Hole Plug Assembly Mechanism for Steam Generators
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Solution Overview
Problem
The existing inspection hole plug designs, such as those described in JPA H06-222189A, face difficulties in assembly due to low workability caused by the need for precise visual alignment of pins and perfect rotational fitting, making it challenging to plug inspection holes efficiently in steam generators.
Innovation Solution
The proposed inspection hole plug incorporates a base with a fitting member that rotates and is guided by a fitting unit, a holding member that abuts on the base, and a fastening member with a stepped portion, allowing for easy assembly by eliminating the need for precise rotational alignment and pin insertion, and ensuring reliable axial movement and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pin is provided at an end of the sleeve for inserting it into the plug, then the plug can be fixed to the plate by inserting the pin through aligned apertures, but visual check is difficult at the time of inserting the pin into the aligned apertures, resulting in low workability
Solution Approach 1:
A guide groove is introduced as an intermediary feature that visually guides the pin insertion process. The guide groove is formed on the sleeve's outer peripheral surface, extending from the open end toward the closed end, providing a visible path that facilitates accurate alignment and insertion of the pin through the apertures while maintaining the fixing reliability of the original pin-sleeve-plate assembly structure
2Reliability
If the connection of the plate and the flange of the plug engage with each other to be perfectly fitted to each other, then the plug can be securely attached, but workability in turning the plug at the time of aligning the respective holes is also low
Solution Approach 1:
The connection between the plate and flange is designed with a dynamic fitting process. The guide groove on the sleeve works in conjunction with the pin to provide both visual guidance and mechanical constraint during the alignment and turning operations. This dynamic system allows for easier alignment while maintaining secure attachment, as the guide groove facilitates the turning motion and hole alignment process
Data Source
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AI summary
[Problem to be Solved] To easily perform assembly at the time of plugging an inspection hole. [Solution] An inspection hole plug 1 that plugs an inspection hole of an outer casing 136 surrounding a tube bundle in a steam generator includes: a base 2 fixed to the outer casing 136 and having an opening 21 that serves as the inspection hole; a fitting member 3 that plugs the opening 21 of the base 2; a fitting unit 4 that guides rotational movement of the fitting member 3 in a circumferential direction along an inner peripheral edge of the opening 21 of the base 2 and restricts the rotational movement by an axial movement of the fitting member 3 parallel to a central axis R of the rotational movement to fit the inner peripheral edge of the opening 21 of the base 2 and an outer peripheral edge of the fitting member 3 to each other; a holding member 5 into which a shaft portion 31 extending from the fitting member 3 along the axial direction is inserted and that is provided to be capable of abutting on the base 2; and a fastening member 6 that is screwed onto the shaft portion 31 of the fitting member 3 and holds the fitting member 3 at a position axially moved by fastening thereof with the holding member 5 abutting on the base 2.