Rolling Mill Bushing Geometry for Inboard Bearing Heat Reduction
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Solution Overview
Problem
The temperature profile within rolling mill oil film bearings, particularly at the inboard side, is uneven due to thinner oil film thickness leading to higher shear rates and increased temperatures, which can cause bearing failure.
Innovation Solution
The bushing design incorporates features such as undercut and ramp portions on its outer surface to allow deflection under load, controlling the maximum radial deflection based on bearing load rating and hydrodynamic length, reducing temperature buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bushing is made rigid to maintain structural stability, then the bearing can support higher loads, but the temperature on the inboard side increases due to thinner oil film and higher shear rates
Solution Approach 1:
The bushing transitions from a rigid structure to a dynamic structure that can deflect under load. The reduced wall thickness in the inboard region allows the bushing to bend and conform to the journal surface, maintaining optimal oil film thickness and reducing shear heating while still supporting heavy loads through the overall bushing structure.
Solution Approach 2:
The bushing wall thickness is varied along its length, with the inboard side having reduced thickness compared to the outboard side. This local modification allows the inboard region to deflect and maintain proper oil film clearance under load, reducing temperature, while the thicker outboard region provides structural support for load bearing.
2Stability of the object's composition
If the bushing wall thickness is increased to reduce deflection, then structural stability improves, but the oil film thickness decreases leading to higher shear rates and temperatures
Solution Approach 1:
The bushing is designed with non-uniform wall thickness, where the inboard side has reduced thickness to allow controlled deflection and maintain oil film clearance, while the outboard side maintains sufficient thickness for structural stability. This local differentiation resolves the contradiction between stability and temperature control.
Solution Approach 2:
The bushing is designed to deflect dynamically under operating conditions. The reduced wall thickness enables the bushing to bend and conform to the journal surface, maintaining adequate oil film thickness and reducing shear heating, while still providing structural support.
3Ease of manufacture
If the bushing is designed with uniform wall thickness, then manufacturing is simplified, but the temperature distribution becomes uneven under load
Solution Approach 1:
The bushing features variable wall thickness with the inboard side having reduced thickness compared to the outboard side. This local modification creates non-uniform thermal characteristics that compensate for the uneven temperature distribution caused by operational conditions, while remaining manufacturable using standard processes.
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 design effectively reduces temperature on the inboard side of the bearing, preventing failure and improving operational efficiency.
Implementation Method 1
the second portion allows the bushing to deflect as load increases at a maximum radial deflection of δ mm
Implementation Method 2
a continuous flow of oil is fed through one of the sets of passageways 29 in the chock, feed openings 30 in the bushing, and rebores 32 in the bearing surface 20. From here, the oil enters between the bearing surface 20 and the rotating journal surface 16 to form a hydrodynamically maintained somewhat wedge-shaped oil film 34
Implementation Method 3
the oil enters between the bearing surface 20 and the rotating journal surface 16 to form a hydrodynamically maintained somewhat wedge-shaped oil film 34 by the bearing load zone 'Z' and the hydrodynamic length 'LH'
Data Source
AI summary
A novel bushing (300) is disclosed as used in a bearing in a rolling mill, where a feature of length l is introduced on the inboard portion (301) of an outer surface (303) of the bushing (300), where the introduced feature allows the bushing (300) to deflect as load increases at a maximum radial deflection of δ mm. The introduced feature deals with elevated temperatures on the inboard side of the bushing (300) by allowing the bushing to deflect as the load increases.