Magnetostrictive Torque Sensor Manufacturing with Residual Austenite Control
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Solution Overview
Problem
Conventional methods for manufacturing magnetostrictive torque sensors face challenges due to nonuniformity in residual austenite content of structural steel shafts, leading to variations in magnetic characteristics and sensitivity, which complicates assembly and increases production costs.
Innovation Solution
A method involving measuring the residual austenite content of rotating shafts and adjusting heat treatment conditions to impart magnetic anisotropy, ensuring uniform sensitivity characteristics by ranking shafts based on measured impedance and applying tailored heat treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional heat treatment is applied to steering shafts with varying residual austenite content, then the manufacturing process remains simple, but the magnetic characteristics and sensitivity uniformity deteriorate
Solution Approach 1:
The patent applies parameter changes by adjusting heat treatment conditions (temperature, time, atmosphere) based on the measured residual austenite content of each steering shaft. Shafts with different austenite content receive customized heat treatment parameters to achieve uniform magnetic characteristics and sensitivity across all sensors, resolving the contradiction between manufacturing simplicity and precision.
2Manufacturing precision
If residual austenite content is regulated to reduce nonuniformity, then sensitivity characteristics uniformity improves, but manufacturing cost and complexity increase
Solution Approach 1:
The patent implements preliminary action by measuring the residual austenite content of each steering shaft before heat treatment and ranking them accordingly. This preliminary characterization allows for optimized heat treatment planning that achieves uniform sensitivity characteristics without requiring complex real-time control systems, thus improving precision while limiting complexity increase.
3Manufacturing precision
If residual austenite content is regulated to reduce nonuniformity, then sensitivity characteristics uniformity improves, but production cost increases
Solution Approach 1:
The patent optimizes heat treatment parameters (temperature, time, cooling rate) based on the measured residual austenite content to achieve uniform sensitivity characteristics. By adjusting these parameters rather than strictly controlling austenite content, the patent reduces production costs while maintaining manufacturing precision.
4Manufacturing precision
If shafts are ranked and heat treated according to residual austenite content, then sensitivity uniformity improves, but manufacturing time increases
Solution Approach 1:
The patent performs preliminary measurement and ranking of steering shafts by residual austenite content before heat treatment. This allows for efficient batch processing where shafts with similar austenite content are grouped and treated with optimized parameters, achieving uniform sensitivity while minimizing the time penalty through systematic organization rather than individual processing.
Solution Approach 2:
The patent segments the steering shafts into groups based on their residual austenite content rankings. Each segment receives customized heat treatment parameters optimized for its specific austenite range, achieving uniform sensitivity characteristics across all segments while enabling parallel processing to reduce overall manufacturing cycle time.
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 approach reduces nonuniformity in sensitivity characteristics, simplifies assembly, and lowers production costs by using conventional materials, improving sensor yield and reducing worker burden.
Implementation Method 1
providing the magnetostrictive film with magnetic anisotropy
Implementation Method 2
heat-treating the rotating shaft in a thermostat while the shaft is kept under stress
Implementation Method 3
applying a twisting torque to the rotating shaft to create stress in the circumferential surface of the rotating shaft
Implementation Method 4
magnetostrictive films that are magnetically anisotropic with respect to each other are formed at two specific locations on the surface of the steering shaft
Data Source
AI summary
A method for manufacturing a magnetostrictive torque sensor having low nonuniformity of sensitivity characteristics. The residual austenite content in the rotating shaft of the torque sensor is measured first. A magnetic film is subsequently subjected to a heat treatment under heat treatment conditions that are different for each of the measured residual austenite contents, and magnetic anisotropy is imparted.