Anti-Cross Thread Fastener with Local Thread Height Transition
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Solution Overview
Problem
Current anti-cross thread fasteners have a fixed and longer transitional thread contour length due to manufacturing limitations, leading to unnecessary extra length and reduced functionality, as the thread rolling die's tolerances and height variations result in a longer helical transition than needed, causing wasted space and non-functional thread sections.
Innovation Solution
The transitional thread contour length is reduced by reconfiguring the helix sections to maintain full anti-cross thread functionality, allowing for a shorter fastener with a novel contour that eliminates unnecessary length, maintaining the desired height transition and thread engagement without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transitional thread contour length is increased to accommodate manufacturing tolerances and height variations in the thread rolling die, then the manufacturing reliability is improved, but the fastener length increases and functionality is reduced
Solution Approach 1:
The patent applies local quality by varying the thread height along the transitional thread contour. The thread height transitions from full height at the standard thread section to reduced height at the anti-cross thread section, with intermediate heights distributed non-uniformly along the transition. This localized variation in thread geometry allows the transition to occur over a shorter axial distance while still accommodating manufacturing tolerances, thereby reducing the overall fastener length without compromising manufacturing reliability.
2Length of moving object
If the transitional thread contour length is reduced to shorten the fastener, then the fastener compactness is improved, but the manufacturing precision requirements increase due to tighter tolerances on the thread rolling die
Solution Approach 1:
The patent applies dynamics by making the thread height a variable parameter along the transitional thread contour rather than a fixed dimension. The thread height dynamically transitions from the full height of the standard thread to the reduced height of the anti-cross thread, with the rate of change optimized to balance compactness and manufacturability. This dynamic approach allows the transition to be completed in fewer helical turns while distributing the dimensional changes in a manner that reduces the stringency of manufacturing precision requirements.
3Length of moving object
If the transitional thread contour is optimized to reduce the number of helical turns, then the fastener length is reduced, but the thread engagement functionality may be compromised
Solution Approach 1:
The patent applies parameter changes by modifying the thread height parameter along the transitional thread contour. Instead of maintaining a constant thread height, the height parameter varies continuously from the standard thread height to the anti-cross thread height over a reduced number of helical turns. This parameter optimization ensures that the transitional thread provides sufficient engagement length and surface area for reliable thread engagement, while still achieving the overall goal of fastener length reduction. The specific distribution of thread heights is designed to maintain adequate bearing area and load distribution.
Data Source
AI summary
A male anti-cross threading fastener comprising: a substantially round shank having a lead end, a torque end, and a plurality of male threads around a circumference of the shank, the plurality of male threads comprising: a standard thread around at least a portion of the circumference of the shank and having a standard thread contour, wherein a width and a thread angle of the standard thread enables engagement with corresponding female threads, wherein the major diameter of the standard thread is between a lower major diameter limit and a higher major diameter limit; a transitional thread around at least a portion of the circumference of the shank and having a transitional thread contour with a width and a thread angle similar to the width and thread angle of the standard thread that enables engagement with corresponding female threads; an anti-cross thread around at least a portion of the circumference of the shank and having an anti-cross thread contour and an outside diameter configured to promote alignment of the male anti-cross thread fastener with a female fastener; and a lead thread around at least a portion of the circumference of the shank and having a lead thread contour, and wherein the transitional thread contour has a height that transitions from the lower major diameter limit of the standard thread to the outside diameter of the anti-cross thread.