Curved Thread Flank Fastener for Loosening Inhibition
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Solution Overview
Problem
Conventional fastening members with thread structures face issues such as loosening due to stress concentration, inadequate frictional force, and difficulty in applying thick plating while maintaining loosening-inhibition effects, leading to potential bolt breakage and laborious resin coating requirements for reuse.
Innovation Solution
The fastening member features a pressure-side flank surface and play-side flank surface with a specific curved shape that disperses force across multiple threads, reducing stress concentration and enhancing elastic deformation, thereby increasing frictional force and allowing for thicker plating without compromising loosening-inhibition effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat flank portion and pressure-contact flank portion are formed on the thread, then loosening inhibition is improved, but stress concentration occurs at the connection between these portions causing plastic deformation or cracks
Solution Approach 1:
The patent applies curvature by forming a rounded connection portion between the flat flank portion and pressure-contact flank portion, replacing the sharp angular connection with a curved transition. This rounded structure distributes stress more evenly across the connection zone, preventing stress concentration that would otherwise cause plastic deformation or cracks, while maintaining the loosening inhibition function.
2Reliability
If the flank angle of the pressure-contact flank is different from the counterpart fastening member, then loosening inhibition is improved, but the contact area becomes small reducing frictional force
Solution Approach 1:
The patent applies local quality by creating a flat flank portion with a specific width in the radial direction, establishing a localized contact zone with optimized geometry. This flat portion provides a sufficient contact area for generating frictional force, while the pressure-contact flank portion maintains its larger flank angle for loosening inhibition. The combination ensures both friction and loosening prevention.
3Ease of operation
If dimensional tolerance is provided in the bolt and nut diameters to enable fastening, then ease of assembly is improved, but loosening occurs due to the tolerance
Solution Approach 1:
The patent applies curvature through the rounded connection portion between the flat flank and pressure-contact flank, creating a stress-distributing geometry that prevents deformation even with dimensional tolerances. This rounded structure maintains consistent contact characteristics across tolerance ranges, enabling both easy assembly and reliable loosening prevention without requiring tight tolerances.
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
This design effectively inhibits loosening, improves fatigue strength, and enables easy reuse of fastening members while maintaining the loosening-inhibition effect even with thick plating, reducing the risk of bolt breakage and simplifying the reuse process.
Implementation Method 1
the thread causes elastic deformation and contacts a root of the internal screw, whereby the contact portion enlarges in series
Implementation Method 2
a large frictional force cannot be obtained because plastic deformation occurs
Data Source
AI summary
A fastening member that exerts a high loosening-inhibition effect is provided.A fastening member 1 has an upper portion 11 on a thread top portion side and a lower portion 12 on a thread root side in at least a part of a thread 10. The upper portion 11 and the lower portion 12 have following constructions. A pressure-side flank surface 13 and a play-side flank surface 14 are formed on the upper portion 11. A pressure-side side surface 15 and a play-side side surface 16 are formed on the lower portion 12. The pressure-side side surface 15 is formed to be continuous from a lower end of the pressure-side flank surface 13. In a cross-section including an axial line of the fastening member 1, a shape of the pressure-side side surface 15 is a curve line shape that curves inward from an extended line of the pressure-side flank surface 13 or a shape provided by combining a straight line shape positioned inside the extended line of the pressure-side flank surface 13 and a curve line shape that curves inward from the extended line.