Sensor Bearing Assembly With Post-Mount Magnetization Accuracy
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Solution Overview
Problem
The classical method of manufacturing sensor bearing units results in a large concentricity defect in the groove of the inner ring, leading to degradation of the total pitch deviation of the magnetic target, which affects the measurement accuracy of the sensor bearing unit.
Innovation Solution
A method involving securing the target holder to the first ring and magnetizing the magnetic target after assembly, which limits the degradation of the total pitch deviation by ensuring accurate positioning and magnetization of the magnetic poles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the groove is soft turned and heat treatment is applied before magnetization, then the manufacturing process is simplified, but the concentricity defect increases and total pitch deviation degrades
Solution Approach 1:
The groove is machined with high precision before assembly, and the target holder is pre-positioned with accurate concentricity. This preliminary precision work is done before the bearing inner ring is subjected to heat treatment and soft turning, so that the magnetic target's concentricity is established before any deformations occur during manufacturing.
Solution Approach 2:
The conventional sequence is inverted: instead of machining the groove first and then assembling the magnetic target, the magnetic target is assembled onto the inner ring first, and only then is the groove machined and heat treatment applied. This inversion ensures that the magnetic target's position is not affected by subsequent manufacturing deformations.
2Ease of manufacture
If the magnetic target is magnetized before assembly, then the magnetization process is easier, but the total pitch deviation degrades due to assembly-induced positioning errors
Solution Approach 1:
The magnetic target is assembled onto the target holder and positioned with high precision before magnetization. This ensures that the magnetic poles are created at the correct positions relative to the bearing's rotation axis, minimizing total pitch deviation. The magnetization is then performed on the already-assembled unit, accepting the slight increase in process complexity to maintain precision.
3Ease of manufacture
If the target holder is secured into the groove after heat treatment, then the groove machining is simpler, but the concentricity defect increases
Solution Approach 1:
The assembly sequence is inverted: the target holder is secured to the inner ring before the groove is machined and heat treatment is applied. This ensures that the concentricity is established before any deformations occur during groove machining and heat treatment, preventing concentricity defects that would otherwise compromise the magnetic target's positioning accuracy.
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 improves the measurement accuracy of the sensor bearing unit by reducing the total pitch deviation, resulting in more precise signal transmission and integration in compact apparatus.
Implementation Method 1
b) magnetizing the magnetic material of the magnetic target after the step of securing the target holder to the first ring
Data Source
AI summary
The method provides for the manufacturing a sensor bearing unit including a bearing having a first ring and a second ring capable of rotating concentrically relative to one another, and an impulse ring provided with a target holder secured to the first ring and with a magnetic target mounted on the target holder. The method further includes securing the target holder to the first ring and magnetizing the magnetic material of the magnetic target after the step of securing the target holder to the first ring.