Locking Bolt With Catenary Skirt Resists Vibration Loosening
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Solution Overview
Problem
Conventional bolts and nuts loosen when subjected to repeated vibrations, and existing solutions require skilled cutting work for manufacturing, leading to high costs and inefficiencies.
Innovation Solution
A locking bolt design featuring a shank section with a hexagonal head and a cylindrical skirt portion formed using a catenary curve surface, where the inner surface is hollowed into an inverted catenary curve shape with a flat bottom rim, and the intersection with the shank is approximately round, combined with a manufacturing method using a header that eliminates the need for cutting work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bolts and nuts are used for fixing members, then the fixing process is simple, but the bolts loosen when vibrations are repeatedly applied
Solution Approach 1:
The patent applies curvature by forming the inner surface of the skirt portion into a catenary curve shape. This curved surface allows the bolt to better conform to the hole surface, distributing stress more evenly and preventing loosening under vibration. The catenary curve specifically provides optimal stress distribution while maintaining manufacturing feasibility through stamping processes.
2Manufacturing precision
If cutting work using a lathe is used to manufacture special shaped fastening members, then the manufacturing precision can be achieved, but the production cost increases and special skill is required
Solution Approach 1:
The patent replaces the mechanical cutting system (lathe) with a stamping/forming system. The head section is formed by stamping a blank material, and the skirt portion is created through forming processes that shape the material plastically. This substitution eliminates the need for skilled cutting operations while achieving the required geometric precision through die design.
Solution Approach 2:
The patent changes the manufacturing approach from subtractive (cutting) to formative (stamping and forming). By controlling parameters such as stamping force, forming temperature, and die geometry, the complex catenary curve shape and integrated head section can be produced efficiently without requiring skilled manual cutting operations.
3Reliability
If a tapered section with conical and concave curve surfaces is used to absorb vibrations, then the locking action is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the head section and skirt portion into a single integrated component formed in one stamping operation. The head section provides the fastening interface while the skirt portion with its catenary curve inner surface provides vibration absorption and locking. This integration eliminates the need for separate tapered sections or multiple assembly steps, reducing complexity while maintaining the vibration-absorbing functionality.
Data Source
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AI summary
It is an object to provide a locking bolt, which is capable of tightly fixing a member or the like at an extremely high degree of firmness without being loosened even when vibrations are repeatedly applied thereto, and is manufactured in an extremely facililated manner. The locking bolt includes: a shank section (1) threaded on an outer circumference thereof; and a head section (2) provided at one end of the shank section (1). The head section (2) includes: a main body portion (201) having a hexagonal cross-sectional shape; and a cylindrical skirt portion (202) provided continuously with the main body portion (201) and formed so as to be spaced radially outward from the main body portion (201) in an expanding manner along a concave surface using a catenary curve surface. The locking bolt has a structure in which: a lower edge surface (203) of an outer surface of the cylindrical skirt portion (202) is parallel to an axis (X-X) of the main body portion (201); and an inner surface of the cylindrical skirt portion (202) is hollowed into an inverted catenary curve surface-like shape with a flat portion left on a bottom rim (204).