Rolling Mill Bearing Sleeve Geometry for Inboard Temperature Reduction
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Solution Overview
Problem
Conventional rolling mill bearings experience elevated temperatures and potential failure due to thinner oil film thickness and higher shear rates at the inboard side, leading to increased bearing temperatures and potential edge wipe.
Innovation Solution
The sleeve in the rolling mill bearing is modified with a conically shaped first portion and a second portion featuring an undercut or ramp structure to allow deflection under load, controlling the maximum radial deflection based on bearing load rating and hydrodynamic length ratios, thereby adjusting film thickness dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the sleeve has a standard cylindrical inner surface, then the manufacturing is simple and consistent, but the temperature buildup on the inboard side increases due to thinner oil film thickness
Solution Approach 1:
The sleeve inner surface is modified with a non-uniform geometry featuring an undercut region at the inboard end, creating locally varying film thickness. This allows the oil film to be thicker at the inboard side where temperature buildup occurs, while maintaining standard geometry elsewhere, thus reducing temperature without requiring complete redesign of the entire sleeve
Solution Approach 2:
The sleeve inner surface is divided into distinct zones: a first region with standard taper, a second region with undercut geometry, and a third region with modified taper. This segmentation allows each zone to serve specific functions - the undercut zone specifically addresses the temperature problem at the inboard end while other zones maintain standard loading characteristics
2Temperature
If the oil film thickness is increased at the inboard side to reduce temperature, then the temperature buildup decreases, but the shear rate increases leading to potential edge wipe
Solution Approach 1:
The sleeve geometry is designed to deflect dynamically under load, with the undercut region allowing controlled radial deflection of the sleeve. This dynamic adjustment optimizes the oil film thickness during operation - maintaining thicker film at the inboard side for temperature reduction while preventing excessive film thickness that would cause edge wipe, thus balancing temperature control with bearing reliability
Solution Approach 2:
The sleeve inner diameter geometry is modified by introducing an undercut dimension and varying taper angles in different zones. These parameter changes create a non-uniform film thickness distribution that reduces the minimum film thickness at the inboard side under load, thereby reducing temperature buildup while maintaining sufficient film thickness to prevent metal-to-metal contact and edge wipe
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 modification reduces temperature buildup on the inboard side, enhancing bearing performance and reducing the risk of failure by managing deflection and film thickness, thus improving operational efficiency.
Implementation Method 1
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 by the bearing load zone 'Z' and the hydrodynamic length 'LH'
Data Source
AI summary
A novel sleeve is disclosed as used in a roll in a rolling mill, where a feature of length l is introduced on the tapered end of the inboard portion of an inner surface of the sleeve, where the introduced feature allows the sleeve to deflect as load increases at a maximum radial deflection of δ. The introduced feature deals with elevated temperatures on the inboard side of the sleeve by allowing the sleeve to deflect as the load increases.