Reverse Self-Tapping Fastener With Spiral Anti-Loosening Nut
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Solution Overview
Problem
Conventional fastening devices with screws or bolts tend to loosen in vibrational environments, necessitating improved anti-loosening solutions that allow for easier assembly and secure fastening from either end.
Innovation Solution
A fastening device comprising a reverse self-tapping screw with a tapered section and a threaded shank, combined with an anti-loosening assembly featuring an internally threaded fastening element and a retaining ring with spiral constriction grooves at a 30°-60° angle, allowing for secure assembly from either end and enhanced anti-loosening capabilities through heat treatment and forging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screw or bolt and nut combination is used, then the work piece can be fastened in a static state, but the work piece will loosen in a vibrational environment
Solution Approach 1:
The fastening device is divided into multiple functional segments: a reverse self-tapping screw portion for initial insertion and anchoring, a forward threaded screw portion for nut engagement, and a separate anti-loosening assembly with spiral constriction grooves. This segmentation allows each component to perform its specific function optimally while maintaining ease of assembly from either end.
Solution Approach 2:
The screw features a reverse self-tapping portion at one end and a forward threaded portion at the other end. This inverted dual-threading approach allows the fastening element to be inserted and secured from either direction, simplifying assembly operations while the spiral constriction grooves provide the anti-loosening effect through a different mechanical mechanism than conventional locknuts.
2Ease of operation
If a reverse self-tapping screw with tapered section is used, then assembly can be performed from either end, but the threading complexity increases
Solution Approach 1:
The screw is segmented into distinct functional portions: a reverse self-tapping portion with tapered external threads for initial insertion, and a forward threaded portion with standard right-hand threads for nut engagement. This clear segmentation manages complexity by giving each section a specific, simple function rather than attempting a single complex threading pattern.
Solution Approach 2:
The dual-threaded screw design provides multi-functionality: the reverse self-tapping portion enables insertion from either end of the workpiece, while the forward threaded portion provides standard nut engagement. This universal design approach allows the same fastener to perform multiple functions that would otherwise require different fastening components.
3Reliability
If spiral constriction grooves are added to the anti-loosening member, then anti-loosening effect is improved, but the manufacturing complexity increases
Solution Approach 1:
The spiral constriction grooves are defined by specific geometric parameters: an included angle between 30°-60° and a depth of d/32 where d is the nominal diameter. By standardizing these parameters, the manufacturing process becomes more controlled and repeatable, reducing complexity while ensuring consistent anti-loosening performance across production batches.
Solution Approach 2:
The constriction grooves are formed on the anti-loosening member before final assembly, typically through forging or heat treatment processes. This preliminary formation of the spiral grooves integrates the anti-loosening feature into the base component rather than requiring separate machining operations or additional parts, thereby reducing overall manufacturing complexity.
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 enables easy assembly and secure fastening of work pieces from either end, effectively preventing loosening in vibrational conditions, while the heat-treated and forged components ensure a strong fit between the fastening element and reverse self-tapping screw.
Implementation Method 1
The anti-loosening member of the fastening element is subjected to a heat treatment method in which the constriction grooves are constricted by forging
Implementation Method 2
The anti-loosening member includes the plurality of spiral constriction grooves having an inclined angle of 30°-60° with respect to an axis thereof
Data Source
AI summary
A fastening device includes a reverse self-tapping screw including a nut and a threaded shank having a tapered section and a threaded section wherein the tapered section is a reverse self-tapping screw formed on the threaded shank adjacent to the nut and has a length of d/4 to d/3; the reverse self-tapping screw is a screw having a tapered surface of 1.5×d/16; and the threaded section is a forward threaded screw; and an anti-loosening assembly including an internally threaded fastening element and a retaining ring. The internally threaded fastening element includes a nut member and an anti-loosening member having a plurality of spiral constriction grooves. The spiral constriction grooves have an inclined angle of 30°-60° with respect to an axis thereof, and an annular groove for securely receiving the retaining ring.