Anti-Backlash Device with Cylindrical Pressure Actuator
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Solution Overview
Problem
Existing screw and nut mechanisms, such as Acme lead screws and ball screws, suffer from inefficiencies due to backlash, which is exacerbated by temperature sensitivity and thread profile deviations, leading to low efficiency and bulkiness in anti-backlash devices.
Innovation Solution
An anti-backlash device with a cylindrical pressure actuator and cradle having helical threads, where only one face of each component needs to be accurately machined, providing a full 360-degree active circle for rollers to apply balanced forces and prevent backlash, while being compact and low-friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Acme lead screw and nut devices are used, then the structure is simpler, but the efficiency is very low (around 50%) due to backlash
Solution Approach 1:
The nut is divided into two separate nuts that can be adjusted relative to each other. Each nut engages with the screw threads independently, allowing separate adjustment to eliminate backlash while maintaining the simple Acme screw structure. This segmentation enables the system to achieve high efficiency without complicating the fundamental screw mechanism.
2Reliability
If prior art anti-backlash screw and nut devices are used, then backlash is reduced, but the device becomes very bulky and large in volume
Solution Approach 1:
One nut is positioned inside or adjacent to the other nut, with both nuts sharing the same space around the screw. The nested arrangement allows the anti-backlash mechanism to be compact, eliminating the need for bulky external structures while effectively reducing backlash through the adjustable dual-nut configuration.
3Loss of energy
If ball screws with multiple rolling balls and complex return systems are used, then efficiency and accuracy are improved, but the device complexity increases
Solution Approach 1:
The invention extracts and eliminates the complex ball return systems, multiple rolling balls, and intricate helical grooves from the design. Instead, it uses a simpler adjustable dual-nut mechanism that achieves comparable or superior efficiency without the complicating factors of ball screw systems, thereby reducing device complexity while maintaining high performance.
4Ease of manufacture
If Acme lead screw is used, then the structure is easier to manufacture, but it has difficulty maintaining efficient rotation without pitch deviation and backlash
Solution Approach 1:
The nut assembly is made dynamically adjustable, allowing the position of each nut to be modified to compensate for manufacturing variations in the screw threads. This dynamic adjustment capability enables the system to maintain precise engagement and eliminate backlash even when the screw has pitch deviations, thereby achieving high manufacturing precision without sacrificing ease of manufacture.
Data Source
AI summary
An anti-backlash device for preventing backlash derived from a moving load on a screw used in converting rotary motion into linear motion, the anti-backlash device comprising: a cylindrical pressure actuator integrally formed with a helical thread and axially mounted on the screw; a cradle integrally formed with a helical thread and internal cradle threads, the cradle being mounted exterior to and in mechanical contact with both the cylindrical pressure actuator and the screw, and a preloading means comprising a wave spring and a retainer mounted in the cradle.