Anti-loosening Bolt and Nut with Foldable Tip and Odd Grooves
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Solution Overview
Problem
Existing bolt and nut systems with rotation prohibition mechanisms have limited angular resolution, leading to either excessive or insufficient torque management, and are prone to loosening under vibration, particularly in applications like aircraft maintenance where precise torque control and frequent loosening are required.
Innovation Solution
A bolt with a foldable part that can be folded around a perpendicular axis, paired with a nut having an odd number of radially arranged grooves at equal angular intervals, allowing for higher angular resolution of rotation prohibition and incorporating a clutch mechanism to manage excessive torque, enabling precise torque control and secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of grooves is increased to achieve higher angular resolution for torque management, then the precision of rotation prohibition is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies asymmetry by using an odd number of grooves (3, 5, or 7) arranged radially at equal angular intervals, creating an asymmetric configuration that enables higher angular resolution. This asymmetric arrangement allows the foldable part to engage with grooves at multiple discrete angular positions, achieving 120°, 72°, or 51.4° resolution respectively, without requiring a symmetric even-numbered distribution that would limit angular differentiation.
Solution Approach 2:
The solution segments the rotation prohibition function into multiple discrete angular positions defined by the odd-numbered grooves. Instead of continuous rotation control, the system divides the 360° range into specific angular segments where the foldable part can engage with individual grooves, providing precise torque management at each segment while maintaining a relatively simple overall structure.
2Measurement precision
If the number of grooves is increased to achieve higher angular resolution, then the torque management precision is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The asymmetric odd-numbered groove configuration optimizes torque management precision by creating distinct angular engagement positions. The asymmetry ensures that each groove provides a unique angular reference point, enabling precise torque control at 120°, 72°, or 51.4° intervals, while the regular equal-interval spacing maintains manufacturability through predictable tooling paths.
Solution Approach 2:
The patent changes the parameter of groove quantity from conventional even numbers to odd numbers (3, 5, or 7), which fundamentally alters the angular resolution capability. This parameter change enables higher precision torque management without proportionally increasing manufacturing complexity, as the odd-numbered configuration with equal angular intervals can be achieved through standardized machining processes.
3Reliability
If a foldable part is provided at the tip of the bolt to prohibit rotation, then the reliability of fixation is improved, but the ease of operation deteriorates due to limited angular positions
Solution Approach 1:
The rotation prohibition mechanism is segmented into multiple discrete angular positions through the odd-numbered grooves. The foldable part can engage with any of the 3, 5, or 7 grooves arranged at equal angular intervals, providing segmented but flexible angular adjustment options. This segmentation maintains reliable fixation at each position while offering operational flexibility to select from multiple angular configurations.
Solution Approach 2:
The foldable part provides dynamic adjustment capability, allowing the user to selectively engage different grooves at different angular positions. The foldable mechanism enables transition between engaged and disengaged states, providing operational flexibility to achieve reliable fixation at the most appropriate angular position for each application scenario.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A set of a bolt and a nut having a rotation prohibiting mechanism comprises a foldable part (30) at the tip of a bolt (20), that can be folded around an axis perpendicular to a bolt axis. A tip portion (30) can be folded to either sides with the direction extending along the bolt axis as a center. Grooves (18a-18g) for storing the foldable part (30) are formed on a tip surface (a surface from which the tip of the bolt projects out when the bolt and the nut are tightened) of the nut (12) or the knob (18). A number of the grooves is an odd number. The grooves are arranged radially with equal angular intervals with a center at a screw hole of the nut. For example, seven grooves are arranged radially with equal angular intervals. In this case, the angle between adjacent two grooves is about 51.4 degrees, and this angle is to be an expected angular resolution of the rotation prohibition. However, according to the above mentioned set of the bolt and the nut, the expected angular resolution can be halved (i.e. 25.7 degrees).