Radial Anti-Backlash Nut With Adjustable Collet Preload
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional linear actuators face challenges with high spring force variability due to manufacturing tolerances and limited critical speed, leading to reduced thrust performance and increased vibration, especially when operating at high speeds.
Innovation Solution
An improved radial-type anti-backlash mechanism with a multi-finger collet and spring setup integrated within a separate housing, featuring adjustable spring load controlled by three tolerances: taper angle of collet fingers, spring compression, and collet finger mismatch, allowing for consistent preload adjustment and increased axial stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spring-type anti-backlash mechanisms are used, then backlash is eliminated, but spring force variability due to manufacturing tolerances reduces thrust performance
Solution Approach 1:
The patent changes the parameter of force application from spring-based to friction-based. The friction-based mechanism uses a coefficient of friction between 0.15 and 0.35 to maintain constant axial load, eliminating the variability inherent in spring mechanisms while maintaining reliable backlash elimination.
Solution Approach 2:
The patent replaces the spring-based mechanical system with a friction-based mechanical system. Instead of relying on elastic deformation and spring force, the invention uses friction between contacting surfaces to generate the necessary axial load, fundamentally changing the mechanical principle while achieving better force consistency.
2Stability of the object's composition
If high spring force is used to maintain preload, then axial stiffness increases, but critical speed decreases leading to increased vibration
Solution Approach 1:
The patent changes the parameter of force generation from elastic spring force to friction-based force. This allows maintaining the necessary axial stiffness through friction coefficient control while avoiding the excessive spring forces that would reduce critical speed and increase vibration.
3Manufacturing precision
If multiple tolerance parameters are controlled for adjustable load, then load consistency improves, but device complexity increases
Solution Approach 1:
The patent extracts the complexity of adjustable load mechanisms by using a fixed friction coefficient design. Instead of requiring adjustable components and multiple tolerance controls, the invention achieves load consistency through the inherent properties of friction between standardized surfaces, simplifying the overall device.
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
This solution reduces radial play, enhances critical speeds, and provides superior heat dissipation, while allowing for easier assembly and consistent load setting, thereby improving thrust capability and operational stability.
Implementation Method 1
a spring between the two components that force each part against opposing flanks of the screw thread. This spring biasing takes up the clearance between all the components to get rid of the backlash
Implementation Method 2
Radial anti backlash nuts have a nut body with flexible collet fingers that close to squeeze the threads of the nut into the flank angle of the lead screw, removing the backlash
Implementation Method 3
In a torsional anti-backlash nut, a spacer that separates the two nut halves automatically adjusts with the use of a torsion spring to lengthen and take up the gap, so the nut maintains zero backlash
Data Source
AI summary
A radial-type anti-backlash nut for use upon linear actuator leadscrews uses a separate housing resting upon the actuator's main nut. The anti-backlash action is a multi-finger collet and spring setup located inside the housing. The collet tapers radially inward toward tips of the fingers at a specified taper angle. The whole interior length of an internal thread of the collet engages an external thread of the leadscrew. The housing is a pre-load nut with an internal tapered surface that mates with the collet fingers with substantially the same taper angle. The pre-load nut, when screwed onto external threads of the adjustment nut, both compresses a load spring and applies radially inward adjustable load force to the collet fingers against the leadscrew. Three tolerances adjust load: the taper angle of the main nut's collet fingers, the spring load's compression, and the collet finger mismatch with respect to the lead screw.