Counter-Threaded Bolt Fastener for Vibration-Resistant Joints
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Solution Overview
Problem
Existing bolted joints are prone to loosening due to vibration and prevailing torque, as existing locking methods such as locknuts, jam nuts, and thread-locking fluids are not entirely satisfactory and often unreliable.
Innovation Solution
A bolt design featuring counter-threads with different pitches and diameters, where one external thread twists in one direction and the other in the opposite direction, combined with a nut having an internal thread that matches one of the external threads, allowing for secure assembly and disassembly without loosening, using a combination of a standard left-handed and right-handed thread configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard locking methods (locknuts, jam nuts, thread-locking fluids) are used, then bolted joints can be assembled and disassembled, but they are prone to loosening due to vibration and prevailing torque
Solution Approach 1:
The bolt is divided into two distinct threaded sections: a first external thread with left-handed twist and a second external thread with right-handed twist. Each thread engages with a corresponding internal thread in a separate component (nut and anchor, respectively). This segmentation allows each thread to independently resist loosening forces in opposite directions, providing comprehensive vibration and torque resistance without requiring additional locking mechanisms.
Solution Approach 2:
The invention employs asymmetric thread configurations with different hand orientations (left-handed vs. right-handed) and different pitches. The first external thread has a first pitch while the second external thread has a second pitch different from the first. This asymmetry creates differential engagement characteristics that prevent simultaneous loosening of both threads under vibration and prevailing torque, significantly improving joint reliability.
2Reliability
If counter-threads with different pitches and diameters are used, then resistance to loosening is improved, but device complexity increases
Solution Approach 1:
The invention merges the functions of multiple locking mechanisms into a single integrated bolt design. The counter-threads with different pitches and hand orientations are combined in one bolt shaft, eliminating the need for separate locknuts, jam nuts, or thread-locking fluids. This consolidation maintains reliability while reducing overall assembly complexity by replacing multiple components with one multifunctional fastener.
Solution Approach 2:
The bolt serves multiple functions simultaneously: the first external thread provides locking engagement with the nut, the second external thread provides locking engagement with the anchor, and the unthreaded body portion provides structural connection between them. This multi-functionality allows a single component to replace what would traditionally require multiple separate locking elements, reducing device complexity while maintaining high reliability.
3Reliability
If a bolt with two external threads of different pitches is used, then loosening resistance is improved, but manufacturing precision requirements increase
Solution Approach 1:
Different sections of the bolt shaft have different thread properties optimized for their specific functions. The first external thread has a first pitch and diameter suited for engagement with the nut, while the second external thread has a different pitch and diameter optimized for engagement with the anchor. The unthreaded body portion provides a transition zone. This local differentiation allows each thread to be manufactured with appropriate tolerances for its specific application, balancing reliability requirements with manufacturing feasibility.
Data Source
AI summary
A bolt includes a shank having a first end, a second end, a first external thread proximate to the first end, and a second external thread proximate to the second end. The first external thread twists in a first direction, the second external thread twists in a second direction, and the first direction is different from the second direction. The first external thread includes a minor diameter, the second external thread includes a major diameter, and the minor diameter of the first external thread is greater than the major diameter of the second external thread.