Hub Unit Bearing Assembly for Accurate Rolling Preload Control
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Solution Overview
Problem
The existing methods for manufacturing hub unit bearings fail to accurately control the preload applied to the rolling bodies, as they do not account for the expansion of the inner ring during press fitting with the hub spindle, leading to potential issues with bearing life, dynamic torque, and drivability.
Innovation Solution
A method that involves measuring the outer-diameter dimension of the inner ring before and after swaging, calculating the decrease in axial clearance, and using this information to control the preload, ensuring it falls within a proper range by considering the expansion during both swaging and press fitting processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inner ring is externally fitted with the hub spindle by press fitting, then the inner ring expands and the rolling bodies are press fitted toward the axially outboard side, but the amount of expansion during press fitting is not accounted for in existing methods, leading to inaccurate preload control
Solution Approach 1:
The method measures the outer-diameter dimension of the inner ring before press fitting with the hub spindle, and calculates the expected expansion amount based on this preliminary measurement. This preliminary action allows the preload control to account for the expansion that will occur during press fitting, rather than discovering it too late in the process.
Solution Approach 2:
The method uses feedback by measuring the actual outer-diameter dimension of the inner ring before press fitting, calculating the expected expansion, and then using this information to adjust and control the final preload applied to the rolling bodies. This closed-loop feedback approach ensures accurate preload control despite the expansion that occurs during assembly.
2Reliability
If the preload applied to the rolling bodies is too large, then the life of the hub unit bearing is reduced and dynamic torque increases, but if the preload is too small, then moment rigidity is insufficient
Solution Approach 1:
The method precisely controls the preload parameter by measuring the inner ring's outer-diameter dimension before press fitting, calculating the expansion amount, and adjusting the preload application accordingly. This parameter control ensures the preload falls within the optimal range that simultaneously ensures bearing life and moment rigidity.
Solution Approach 2:
The method replaces purely mechanical trial-and-error preload adjustment with a calculated approach based on measured dimensions and expansion calculations. By substituting the mechanical intuition-based method with a measurement-and-calculation-based method, the preload can be precisely controlled to achieve both reliability and strength requirements.
3Measurement precision
If the inner ring expands during press fitting, then the rolling bodies are press fitted and preload increases, but existing methods only measure expansion after swaging, not during press fitting
Solution Approach 1:
The method performs a preliminary measurement of the inner ring's outer-diameter dimension before press fitting with the hub spindle. This preliminary measurement captures the starting dimension, allowing the expansion during press fitting to be calculated and accounted for in the preload control process.
Solution Approach 2:
The outer-diameter dimension measurement serves as an intermediary parameter that links the press fitting process to the final preload control. By measuring this intermediate dimension before press fitting and calculating the expected expansion, the method creates a bridge between the assembly process and the final preload application.
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 allows for more precise control of the preload, enhancing the accuracy and effectiveness in maintaining optimal bearing performance by accounting for the expansion effects during the manufacturing process.
Implementation Method 1
a swaged portion that is formed by plastically deforming a tubular portion of a tubular fitting portion
Implementation Method 2
when the inner ring expands (outer-diameter dimension of the inner ring increases) as the inner ring is externally fitted with the hub spindle by press fitting
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3
AI summary
To achieve a method that is capable of more accurately controlling a preload applied to rolling bodies. An amount of decrease ΔC in an axial clearance of a hub unit bearing 1 is found based on an amount of expansion ΔD of an inner ring, which is the difference between the outer-diameter dimension D1 of the inner ring 13 after the inner ring 13 is externally fitted with a tubular fitting portion 17 of a hub spindle 14 and after formation of a swaged portion 19, and an outer-diameter dimension Do of the inner ring 13 before the inner ring 13 is externally fitted with the tubular fitting portion 17.