Single-Nut Screw Structure for Accurate Preload Detection
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Solution Overview
Problem
Screw devices that apply preload with a single nut face challenges in detecting preload due to minimal strain on the outer surface of the nut, making it harder compared to double nut systems.
Innovation Solution
A preload detectable screw device design featuring a screw shaft with an outer helical groove, a nut with an inner helical groove and a return path, and a strain sensor attached to the nut's outer surface, with holes provided between the attachment surface and the inner surface to increase strain detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain sensor is attached to the outer surface of the nut in a single nut preload system, then preload detection is enabled, but the strain signal is too weak for accurate detection
Solution Approach 1:
The patent introduces holes at specific locations on the nut body to create localized stress concentration zones. This modifies the local quality of the nut structure, causing strain to concentrate at specific boundaries rather than being uniformly distributed, thereby amplifying the strain signal at the measurement location for better detection accuracy
2Measurement precision
If holes are provided in the nut to increase strain concentration, then strain detection sensitivity increases, but the nut structure becomes more complex
Solution Approach 1:
The patent segments the nut structure by introducing holes that divide the solid nut body into regions with different stress characteristics. This segmentation creates distinct deformation zones and stress concentration boundaries, enabling enhanced strain detection while maintaining a relatively simple overall nut geometry
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 holes on the nut enhance strain detection by creating stress concentration at deformation boundaries, increasing strain sensitivity up to 3.5 times, facilitating accurate preload monitoring and reducing noise interference.
Implementation Method 1
a strain sensor attached to an outer surface of the nut
Implementation Method 2
A stress concentration occurs at the boundary between a portion that deforms and a portion that resists deformation on the outer surface of the nut
Data Source
AI summary
A screw device is provided which applies preload with a single nut and can easily detect preload. The screw device of includes: a screw shaft having an outer helical groove; a nut fitted on the screw shaft, the nut having an inner helical groove, and a return path to which a passage formed between the outer groove and the inner groove is connected; a plurality of rolling elements placed between the passage and the return path; and a strain sensor attached to an outer surface of the nut. At least one hole is provided between an attachment surface, to which the strain sensor is attached, of the nut and/or a vicinity thereof and an inner surface of the nut.