Intermittent Screw Thread Geometry for Rapid Axial Advancement
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Solution Overview
Problem
Existing threaded fasteners lack efficient mechanisms for rapid axial advancement and retraction, universal assembly methods, and reduced thread stripping capacity, particularly in applications requiring quick assembly and disassembly, space-constrained environments, and controlled linear or rotational displacements.
Innovation Solution
The implementation of intermittent screw thread geometry with alternating thread and gap segments along a helical path, allowing for step-wise axial movement and mode switching between rapid lead and continuous threading, enabled by odd-numbered thread/gap features per revolution, and reduced axial load-bearing capacity through specific thread geometry configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous helical thread geometry is used, then thread strength and load-bearing capacity are improved, but axial advancement speed and assembly time deteriorate
Solution Approach 1:
The continuous helical thread is segmented into discrete thread segments separated by gaps along the helical path. This segmentation allows the thread to advance axially in discrete steps rather than continuously, enabling rapid positioning at multiple locations along the fastener axis while maintaining thread strength through proper segment design and distribution.
Solution Approach 2:
The thread geometry transitions from a static continuous form to a dynamic segmented form that can selectively engage and disengage from the mating thread. This dynamic characteristic enables the thread to rapidly advance to different axial positions by rotating the fastener, providing controlled linear displacement while maintaining structural integrity when engaged.
2Strength
If single-start thread form is used, then thread strength is improved, but axial advancement per revolution deteriorates
Solution Approach 1:
The invention introduces a temporal dimension to the thread advancement process by using segmented threads that engage at different axial positions during rotation. Instead of advancing continuously along a single helical path, the segmented thread engages multiple discrete axial positions, effectively adding a dimensional aspect to the advancement mechanism that increases total axial coverage while maintaining single-start strength characteristics.
3Productivity
If intermittent thread segments with gaps are used, then rapid axial positioning is improved, but thread stripping capacity deteriorates
Solution Approach 1:
Different regions of the thread structure are assigned different functions: thread segments provide localized engagement points for rapid axial positioning, while the gaps provide clearance for rapid repositioning. The overall thread assembly maintains adequate stripping capacity through the cumulative effect of multiple segments engaging the mating thread, with each segment contributing to the total load-bearing capability while enabling rapid positioning between engagements.
4Speed
If multiple thread starts are used, then axial advancement speed is improved, but thread complexity and manufacturing difficulty worsen
Solution Approach 1:
Instead of creating multiple simultaneous helical paths as in multi-start threads, the invention segments a single helical path into discrete sections. This approach achieves similar rapid advancement functionality by engaging different axial positions sequentially during rotation, while avoiding the manufacturing complexity of forming multiple precise helical paths simultaneously.
Data Source
AI summary
Intermittent screw thread geometry with a rapid step-wise lead feature when external threads are engaged with internal threads of reflective geometry. In an embodiment, thread segments are alternated with unthreaded segments of equal arc length along a helical path of a single-start thread form which results in an odd number of alternating thread/gap features along the helical path per revolution of the thread body. When such external intermittent threads engage internal intermittent threads of reflective geometry, an external thread body can be axially advanced or retracted through an internal thread body in a rapid step-wise fashion by turning the external thread body in either the clockwise or counterclockwise direction, or in both directions alternately, with respect to the internal thread body when a net axial force is applied to the external threaded body with respect to the internal thread body in the desired linear direction of travel.