Lock Ring for Threaded Stud Rotation Prevention
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Solution Overview
Problem
The existing methods for connecting members using threaded studs often result in undesired rotation of the stud due to friction, leading to microcracks and corrosion, and require complex tools for removal.
Innovation Solution
A lock ring made of the same material as the housing, with a tapered toothed portion and a truncated-cone-shaped surface, is used to secure the threaded stud, preventing rotation and eliminating the need for cadmium-plated lock washers by providing frictional engagement without material damage or corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a toothed lock washer is used to prevent stud rotation, then the stud is secured against rotation, but microcracks form on the housing and corrosion is initiated
Solution Approach 1:
The lock ring is made of the same material (aluminium or magnesium) as the housing, eliminating material incompatibility. This homogeneity prevents galvanic corrosion and avoids the hardness mismatch that causes microcracks when steel washers engage with aluminium/magnesium housing
Solution Approach 2:
The lock ring acts as an intermediary element between the stud and housing. It provides the necessary frictional engagement to prevent rotation while being made of compatible material, thus mediating between the need for rotation prevention and the need to avoid damage to the housing
2Reliability
If a toothed lock washer is used to prevent stud rotation, then the stud is secured against rotation, but complex tools are required for removal
Solution Approach 1:
The lock ring is designed to be extracted or removed easily from the housing seat. The tapered configuration allows it to be pushed out axially without requiring milling machines or special cutters, thus extracting the complexity of the removal process while maintaining the rotation prevention function during operation
3Reliability
If a steel lock washer is used to prevent stud rotation, then friction engagement is achieved, but the harder material damages the softer housing
Solution Approach 1:
The lock ring is made of the same material (aluminium or magnesium) as the housing, eliminating material incompatibility. This homogeneity prevents galvanic corrosion and avoids the hardness mismatch that causes microcracks when steel washers engage with aluminium/magnesium housing
Solution Approach 2:
The material hardness parameter of the lock ring is changed to match the housing material, rather than using a harder material like steel. This parameter change ensures that the frictional engagement does not cause microcracks or damage to the housing while still providing sufficient friction to prevent rotation
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 lock ring effectively prevents stud rotation and microcrack formation, reduces corrosion risk, and allows for easy removal without complex tools, enhancing reliability and cost-effectiveness in applications like aircraft components.
Implementation Method 1
The radially outer second surface of the washer forms teeth on the inner surface of the seat on the housing. The stud is thus prevented from rotating with respect to the housing by the friction produced between the second surface of the washer and the seat on the housing, and between the first surface of the washer and the stud teeth.
Implementation Method 2
When screwing and unscrewing the nut, friction between the nut thread and the second thread may also result in undesired rotation of the stud with respect to the housing.
Data Source
AI summary
A lock ring for securing a threaded stud to a first member, the ring having a first surface defining the ring on the side facing a first axis of symmetry of the ring, and in which a toothed impression is formed when it is forced onto a toothed portion of the threaded stud; and a conical second surface defining the ring on the opposite side to the first axis, and which is forced inside the first member.