Sensor Bearing Groove Machining for Magnetic Target Concentricity

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Solution Overview

Problem

Conventional methods for manufacturing sensor bearing units result in significant concentricity defects in the mounting groove of the inner ring, leading to increased total pitch deviation errors in the magnetic target, which degrades the accuracy of signal transmission.

Innovation Solution

A method involving hard machining of the groove in the first ring after heat-treatment, followed by securing the target holder inside the groove, minimizes concentricity defects and reduces total pitch deviation variations by removing geometrical defects caused during heat treatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If soft turning is used to machine the groove in the inner ring before heat treatment, then the manufacturing process is simpler and easier to perform, but the groove develops large concentricity defects with the inner ring bore diameter, degrading the total pitch deviation of the magnetic target

Engineering Contradiction:

Improveease of groove machiningVSAvoidconcentricity of groove with inner ring bore

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The groove is hard machined in the hardened first ring blank after heat treatment, which removes the geometrical defects (concentricity errors) that occur during heat treatment. By performing the precision machining operation after the heat treatment process, the groove achieves high concentricity with the inner ring bore diameter, eliminating the need for complex preliminary positioning arrangements.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If the groove is hard machined after heat treatment, then the concentricity defect is minimized and manufacturing precision is improved, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:

Improveconcentricity of groove with inner ring boreVSAvoidcomplexity of manufacturing process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

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 enhances the measurement accuracy of the sensor bearing unit by reducing total pitch deviation errors and improving the concentricity of the groove with respect to the inner ring bore diameter.

Implementation Method 1

applying on a first ring blank a heat-treatment in which the metal is hardened

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS11313415B2Method for manufacturing a sensor bearing unit, and associated sensor bearing unit

Publication Date: 2022.04.26 AB SKF SKF PATENT DEPARTMENT

AI summary

A method for manufacturing a sensor bearing unit includes providing 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 into a groove made in a cylindrical surface of the first ring, and with a magnetic target mounted on the target holder. The method including applying on a first ring blank a heat-treatment in which the metal is hardened, hard machining the groove in the cylindrical surface of the first ring blank after the step of heat treating, and introducing and securing the target holder of the impulse ring inside the groove of the machined first ring. Also a sensor bearing unit.