Ball Screw Preload Sensing via Nut-Mounted Force Sensor
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Solution Overview
Problem
Existing ball screws face decreasing rigidity, positioning precision, and stability due to wear and tear, leading to loss of preload, and existing diagnostic methods are inaccurate and susceptible to environmental factors.
Innovation Solution
A ball screw design incorporating a force sensor mounted on a mounting surface perpendicular to the central axis within the nut, allowing direct sensing of preload, enabling real-time monitoring and accurate adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing diagnostic methods using voiceprint signal filtering and Hilbert-Huang transform are employed, then preload status can be diagnosed, but measurement accuracy is adversely affected by environmental factors such as vibration, noise, or frequency
Solution Approach 1:
The patent replaces the complex signal processing method (voiceprint filtering, EMD, HHT) with a direct force sensor measurement system. The force sensor directly measures the preload force without requiring signal processing, thereby eliminating the adverse effects of environmental factors like vibration and noise that affect signal-based diagnostic methods.
2Reliability
If ball screw is used for a while without preload sensing, then wear and tear occurs among screw, nut, and balls, but preload loss cannot be detected timely, leading to decreasing rigidity and positioning precision
Solution Approach 1:
The patent implements a feedback mechanism by mounting a force sensor on the nut that continuously monitors the preload force. The sensor outputs a signal proportional to the preload, providing real-time feedback on the ball screw's condition. This allows timely detection of preload loss due to wear and tear, enabling maintenance before rigidity and positioning precision deteriorate.
3Measurement precision
If a force sensor is mounted on the nut with mounting surface perpendicular to central axis, then direct preload sensing is achieved, but device complexity increases
Solution Approach 1:
The patent integrates the force sensor mounting function into the existing nut structure by providing a mounting surface on the nut body. This allows the force sensor to be mounted directly on the nut without requiring additional separate components or complex installation structures, achieving direct preload sensing while minimizing added complexity.
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
Enables real-time monitoring and accurate assessment of preload status, reducing the impact of environmental factors and ensuring timely adjustments for maintaining optimal performance.
Implementation Method 1
a force sensor is mounted to the mounting surface. The force sensor can directly sense a preload applied to the nut from the balls, so an output signal of the force sensor can enable a user to monitor the status that the preload of the ball screw is maintained
Data Source
AI summary
A ball screw capable of sensing a preload is formed of a nut having an internal thread surrounding an imaginary central axis, a screw inserted into the nut and having an external thread surrounding the imaginary central axis, and a plurality of balls are mounted between the internal and external threads in a way that the balls roll therebetween. A mounting hole having a mounting surface therein is formed in the nut. The mounting surface corresponds to the internal thread in a way that it is substantially perpendicular to the imaginary central axis. A force sensor is mounted to the mounting surface. The force sensor can directly sense the preload in real time, so it is uneasily adversely affected by any environmental factor to have more accurate sensing result relatively.