Eccentric Non-Loosening Bolt Structure to Prevent Base Fracture
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Solution Overview
Problem
Nonloosening bolts with eccentric threaded engagement tend to break at the base due to stress concentration, compromising their antiloosening effectiveness under vibration or impact.
Innovation Solution
Incorporating a frustoconical protrusion between the cutting plane and the eccentric columnar portion of the second bolt, which increases the diameter at the base and reduces stress concentration, preventing the eccentric columnar portion from breaking by distributing stress through an obtuse angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If eccentric threaded engagement is used to achieve antiloosening effect, then the bolt's ability to resist loosening is improved, but stress concentration occurs at the base of the eccentric columnar portion causing it to break
Solution Approach 1:
The bolt is divided into two separate bolts (first bolt with bolt head and second bolt with bolt tip) that are assembled together. This segmentation allows the eccentric columnar portion to be formed on the second bolt while providing a separate base structure, enabling the antiloosening function to be achieved without compromising the overall strength of the bolt assembly.
Solution Approach 2:
The invention introduces a frustoconical protrusion that extends in the radial dimension from the base of the eccentric columnar portion. This dimensional addition increases the effective base diameter and creates a gradual stress transition zone, reducing stress concentration in the critical area where the eccentric columnar portion meets the bolt shaft.
2Reliability
If the diameter of the eccentric columnar portion is reduced to enhance antiloosening effect, then the eccentricity ratio is improved, but the base becomes more prone to breaking due to increased stress concentration
Solution Approach 1:
The frustoconical protrusion adds a radial dimension to the base structure, creating a gradual transition from the smaller eccentric columnar portion diameter to the larger bolt shaft diameter. This dimensional transition reduces the stress concentration factor while preserving the beneficial eccentricity ratio for antiloosening performance.
Solution Approach 2:
The frustoconical protrusion acts as a stress-cushioning element that is built into the structure beforehand. It provides a gradual stress transition zone that cushions the concentration of stresses before they reach the critical breaking point at the base of the eccentric columnar portion.
3Ease of manufacture
If the cutting plane is made perpendicular to the bolt shaft for manufacturing simplicity, then ease of manufacture is improved, but stress concentration occurs at the interface between the cutting plane and eccentric columnar portion
Solution Approach 1:
The frustoconical protrusion introduces a radial dimension that creates a gradual transition zone between the perpendicular cutting plane and the eccentric columnar portion. This dimensional addition allows the cutting plane to remain perpendicular for ease of manufacture while the conical protrusion itself provides the stress-distributing geometry.
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
The solution enhances the robustness and reliability of the antiloosening effect by preventing the eccentric columnar portion from breaking, even under significant stress, while maintaining the bolt's ability to resist loosening.
Implementation Method 1
Inasmuch as there is an obtuse angle at the cutting plane and the eccentric columnar portion, it is possible to relieve stresses that would otherwise be concentrated thereat
Implementation Method 2
when only the second bolt is rotated in a direction such as tends to cause tightening, the bolts will be respectively misaligned in the radial direction relative to the axis of the threaded hole, causing application of a large stress that acts in the radial direction on the threaded shaft
Implementation Method 3
The large stress which acts in the radial direction based on the principle of the lever as determined by the ratio between the eccentricity and the radius of the shaft of the eccentric columnar portion makes it possible to provide extremely superb antiloosening effect
Data Source
AI summary
A nonloosening bolt may comprise a first bolt and a second bolt. The first bolt may have a bolt head, and the second bolt may have a threaded tip. Conversely, the first bolt may have a threaded tip, and the second bolt may have a bolt head. The first bolt may comprise an eccentric columnar portion having a small-diameter male-threaded portion at an outside circumference thereof. The second bolt may comprise a small-diameter female-threaded hole that threadedly engages with the small-diameter threaded portion. Threaded engagement between the small-diameter threaded portion and the small-diameter threaded hole may result in a constitution in which the central axes and pitches of the threaded portions at the outside circumferences of the first bolt and the second bolt are aligned. An eccentric frustoconical protrusion may be provided at the first bolt so as to fit within an eccentric frustoconical hole provided at the second bolt.