Segmented Spindle Nut Thread for Nanometer Position Stability
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Solution Overview
Problem
Conventional spindle nuts in high-precision adjustment devices experience radial clearance and parasitic movements due to continuous thread engagement, leading to reduced positional stability and repeatability under load fluctuations.
Innovation Solution
A spindle nut with an internal thread interrupted by three equally spaced longitudinal grooves, providing discrete contact points and preventing continuous movement, enhances positional stability and repeatability by binding contact areas to specific locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a continuous thread engagement is used in spindle nuts, then the thread engagement is simple and continuous, but radial clearance and parasitic movements occur leading to reduced positional stability
Solution Approach 1:
The internal thread of the spindle nut is divided into multiple discrete thread segments by introducing longitudinal grooves. This segmentation creates distinct contact zones between the spindle and spindle nut, preventing continuous parasitic movements while maintaining engagement stability. The grooves effectively partition the thread engagement into separable zones that reduce radial clearance effects.
Solution Approach 2:
The longitudinal grooves create localized contact zones within the thread engagement. Instead of uniform continuous contact, the contact is concentrated in specific local regions defined by the groove positions. This local concentration of contact areas improves positional stability by reducing the influence of radial clearance while maintaining reliable engagement.
2Stability of the object's composition
If longitudinal grooves are introduced to interrupt the internal thread, then positional stability improves, but the manufacturing complexity increases
Solution Approach 1:
The internal thread is segmented into discrete sections by longitudinal grooves, which can be manufactured using standard CNC machining operations. The segmentation approach allows for systematic fabrication where grooves are positioned at regular intervals, simplifying the manufacturing process while achieving the desired positional stability.
Solution Approach 2:
The longitudinal grooves introduce an asymmetric feature into the otherwise symmetric threaded structure. This asymmetry is deliberately designed to create discrete contact zones that improve positional stability. The groove geometry and positioning are optimized to balance manufacturing ease with performance requirements.
3Reliability
If the internal thread is divided into multiple segments by longitudinal grooves, then parasitic movements are prevented, but the device complexity increases
Solution Approach 1:
The thread structure is divided into multiple segments separated by longitudinal grooves. This segmentation prevents continuous parasitic movements by creating discrete engagement zones. The segmented design maintains reliability through controlled contact points while the regular spacing of grooves keeps the overall structure relatively simple.
Solution Approach 2:
The longitudinal grooves are positioned at regular periodic intervals around the spindle nut circumference. This periodic arrangement creates a repeating pattern of contact zones that effectively prevents parasitic movements. The periodic structure simplifies manufacturing and analysis compared to irregular segmentation patterns.
Data Source
AI summary
Spindle nut which can be brought into engagement with or engages with a corresponding spindle, wherein the spindle nut comprises an internal thread which is defined by three longitudinal grooves, which run in a direction parallel to a central thread axis A of the spindle nut, which is interrupted, as a result of which three spaced-apart internal thread segments are formed in the spindle nut, and, in case the spindle nut is in engagement with the spindle, the external thread of the spindle is in contact only with the internal thread segments, wherein the spindle nut, with respect to a cross section arranged perpendicular to its central thread axis A, comprises a cross section geometry with an inner cross-section curve K facing the central thread axis, wherein at least the inner thread segments each form a partial circle shaped section of the cross section curve K, wherein the diameter of each partial circle shaped section corresponds to the core diameter of the internal thread, and the partial circle shaped sections of the cross-section curve K are connected via transition sections to longitudinal groove sections of the cross section curve K which are formed by the longitudinal grooves, wherein a distance a between the two transition sections adjoining a longitudinal groove section is smaller than a distance b between the two transition sections which adjoin a partial circle shaped section.