Segmented Nut Anti-Backlash Mechanism for Precision Lead Screws
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Solution Overview
Problem
Current anti-backlash solutions for motor-driven components in precision applications, such as semiconductor manufacturing and fluid flow control systems, are limited by factors like manufacturing tolerance, space constraints, and heat generation, making them unsuitable for applications requiring minimal or zero backlash.
Innovation Solution
An anti-backlash device comprising a first nut with engagement features and a rotation locking mechanism, coupled with a second nut and a spring force biasing member, which maintains engagement with the lead screw to prevent relative rotation and reduce or eliminate backlash, allowing for precise control without increasing motor size or heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If motor power is increased to eliminate backlash, then backlash is reduced, but heat generation increases and motor size increases
Solution Approach 1:
The nut is divided into two separate nut segments that can move independently relative to each other along the lead screw. Each nut segment engages with the lead screw threads, allowing them to flex and maintain contact without requiring increased motor power, thus eliminating backlash while avoiding heat generation from oversized motors
Solution Approach 2:
The two nut segments are designed to move dynamically relative to each other along the lead screw axis. This dynamic adjustment allows the nut assembly to compensate for thermal expansion and maintain optimal engagement with the lead screw threads, eliminating backlash without requiring a larger motor
2Manufacturing precision
If motor power is increased to eliminate backlash, then backlash is reduced, but motor size increases
Solution Approach 1:
The nut is segmented into two independent parts that can move relative to each other, allowing the system to eliminate backlash through the relative motion of the segments rather than through increased motor size. This keeps the motor compact while achieving precision
3Manufacturing precision
If anti-backlash device is added, then backlash is reduced, but device complexity increases
Solution Approach 1:
The anti-backlash mechanism is merged into the nut itself by dividing it into two segments. This integration eliminates the need for separate external anti-backlash devices, reducing overall system complexity while achieving backlash reduction
Solution Approach 2:
One nut segment is positioned within or adjacent to the other segment, creating a nested arrangement. This compact configuration achieves backlash elimination without adding significant space or complexity to the overall device
4Manufacturing precision
If anti-backlash device is added, then backlash is reduced, but available space is consumed
Solution Approach 1:
The anti-backlash mechanism is combined with the existing nut structure, eliminating the need for separate external components. This integration achieves backlash reduction without consuming additional space in the system
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 enables the use of smaller motors, reducing heat generation and increasing the accuracy and reliability of motor-driven piston assemblies, while allowing for lower ready pressure settings without backlash events, thus enhancing the precision and reliability of fluid dispensing and flow control systems.
Implementation Method 1
a spring force biasing member for maintaining a spaced relationship between the first nut and the second nut along the lead screw
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
Backlash in a precision system such as a pumping system can be reduced or eliminated with an anti-backlash device that has a first nut coupled to and fixed in relation to a piston. The first nut and a second nut may engage with a lead screw of a motor driving the piston. Relative rotation between the first and second nuts are limited or prevented. A biasing member maintains a spaced relationship between the first and second nuts along the lead screw such that the first nut remains in engagement with the lead screw to thereby reduce or eliminate backlash when the lead screw is rotated by the motor.