Threaded Connector Anti-Loosening Cam-Lock Design
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Solution Overview
Problem
Conventional threaded connections for cleaning tools, such as those using the ACME ¾-5 thread system, are prone to loosening due to coarseness and lack of sufficient frictional engagement, leading to unintended disengagement when bumped or rotated counter-clockwise.
Innovation Solution
A threaded connector with a helical thread comprising a lead-in section, a transitional cam-locking section, and a friction-locking section, where the friction-locking section is adjacent to the base, and the transitional cam-locking section smoothly transitions between the lead-in and friction-locking sections, providing increased frictional engagement to prevent loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ACME threads are used for connecting cleaning tools to handles, then the connection is simple and easy to manufacture, but the connection loosens when bumped or rotated counter-clockwise due to insufficient frictional engagement
Solution Approach 1:
The thread structure is segmented into three distinct sections: a lead-in section with standard ACME threads for easy engagement, a transitional cam-locking section with increasing major diameter to create locking action, and a friction-locking section with maximum major diameter for preventing loosening. This segmentation allows each section to perform its specific function while maintaining overall simplicity
Solution Approach 2:
Different sections of the thread have different local qualities - the lead-in section has standard thread dimensions for ease of engagement, the transitional section has progressively increasing dimensions to create cam-locking action, and the friction-locking section has maximum dimensions for friction prevention. This local differentiation resolves the contradiction by providing appropriate properties in each location
2Strength
If the thread depth is increased to aid in forming threads in wooden handles, then thread engagement is improved, but the manufacturing complexity and difficulty increase
Solution Approach 1:
The thread structure is divided into sections with progressively increasing major diameters. The lead-in section uses standard dimensions that are easy to form, while the transitional and friction-locking sections gradually increase the diameter to achieve deeper effective engagement without requiring uniformly deep threads throughout the entire length
Solution Approach 2:
The major diameter parameter is changed progressively along the thread length rather than being constant. This allows the thread to achieve strong engagement in the friction-locking section while the lead-in section maintains ease of manufacture with standard dimensions
3Reliability
If mating conical faces with serrations are added to prevent unintended loosening, then friction is increased, but the device complexity increases
Solution Approach 1:
The anti-loosening function is merged into the thread structure itself rather than being a separate feature. The friction-locking section of the thread provides the anti-loosening capability through its geometry and frictional engagement, eliminating the need for separate conical faces with serrations
Solution Approach 2:
The anti-loosening function is extracted from the conventional approach of using separate conical locking faces and is instead achieved through the modified helical thread geometry itself, simplifying the overall structure
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 effectively prevents unintended loosening of the threaded connection by ensuring a tight frictional lock between the male and female threads, enhancing the stability and reliability of cleaning tools attached to handles or poles.
Implementation Method 1
The tip and root of the first helical thread of the friction-locking section are frictionally engaged with the root and tip of the second helical thread of the socket, respectively
Data Source
AI summary
A threaded connector includes a base and a threaded male portion projecting axially outward from the base. The threaded male portion is adapted to mate with an associated threaded female socket. The threaded male portion includes a helical thread comprising three sections: (i) a lead-in section; (ii) a transitional cam-locking section; and, (iii) a friction-locking section. The friction-locking section is located adjacent the base, the lead-in section is spaced from the base, and the transitional cam-locking section connects the lead-in section to the friction-locking section. The helical thread includes a tip and a root. The lead-in section is defined by a first major diameter at the tip of said thread and the friction-locking section is defined by a second major diameter at the tip of the thread. The second major diameter is greater than the first major diameter. The transitional cam-locking section includes a locking cam defined by a varying magnitude major diameter at the tip of the thread that increases from the first major diameter to the second major diameter in a smooth, continuous transition without interrupting the helical thread.