Radially Offset Thrust Bearing Rollers to Limit Edge Spalling
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Solution Overview
Problem
Cylindrical roller thrust bearings experience uneven wear due to sliding phenomena, leading to increased contact pressure and material spalling, particularly at the roller extremities, resulting in peak material wear and reduced service life.
Innovation Solution
The arrangement of cylindrical rollers in a thrust bearing with radially offset second rollers between pairs of first rollers, where the contact surfaces are aligned to distribute wear evenly, reducing peak material stress and spalling by bridging high wear areas with radially offset second rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cylindrical rollers are arranged in a single row circumferentially extending around a bearing race, then the bearing structure is simple, but uneven wear occurs at roller extremities leading to material spalling
Solution Approach 1:
The bearing is divided into multiple roller rows (first row and second row) with different radial positions. Each row segment handles different portions of the load, distributing wear more evenly across all rollers rather than concentrating it at extremities of a single row.
Solution Approach 2:
The solution transitions from a single-row configuration to a multi-row configuration arranged in the radial dimension. The second row of rollers is positioned at a different radial distance from the bearing center than the first row, creating a two-dimensional radial arrangement that eliminates the sliding phenomenon at roller extremities.
2Force
If rollers are positioned at larger diameters to increase load capacity, then the bearing can handle higher loads, but sliding phenomenon increases causing greater material wear
Solution Approach 1:
The load-carrying function is segmented across multiple roller rows at different radial positions. The second row of rollers at a smaller radial diameter handles portion of the load, reducing the sliding velocity and wear rate for those rollers while maintaining overall high load capacity through the combined capability of both rows.
3Reliability
If a peak shape is adopted by the race and/or roller to concentrate contact pressure in the middle area, then local material spalling is prevented, but contact pressure increases leading to accelerated wear
Solution Approach 1:
The contact pressure distribution is segmented across multiple roller rows. Instead of concentrating pressure in a peak shape at the middle of single-row rollers, the pressure is distributed across both rows, with the second row experiencing lower sliding velocities and thus lower wear rates, eliminating the need for peak shaping while maintaining reliability.
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 configuration reduces overall wear, minimizes load concentration, and extends the service life of the bearing by evenly distributing axial loads and reducing the tendency for spalling, while allowing for relative rotation and axial load transmission.
Implementation Method 1
cylindrical rollers arranged circumferentially in a bearing race with their rotational axes pointing radially to the central axis of the thrust bearing
Implementation Method 2
relative speed in the contact areas of the roller and the bearing race generates a sliding phenomenon
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A thrust bearing (10) comprising cylindrical rollers arranged circumferentially in a bearing race with their rotational axes pointing radially to the central axis (A) of the thrust bearing and each having a contact surface extending around and lengthwise of the cylindrical roller, the cylindrical rollers comprising at least pairs of radially adjacent first rollers (1) with a radially inner first roller (1A) of each pair arranged with its rotational axis in alignment with the rotational axis of a radially outer first roller (1B) of the pair, and the cylindrical rollers comprising second rollers (2) with at least one such second roller (2) being arranged between adjacent pairs of first rollers (1) in the circumferential direction, the at least one second roller (2) being offset in the radial direction relative to the radially outer first rollers (1B) between which it is circumferentially arranged, wherein the radial offset is such that a halfway line located halfway along the length of the contact surface of each radially outer first roller (1B) is in circumferential alignment with a quarter-way line located one quarter along the length of the contact surface of the at least one second roller (2) from a lengthwise end of the contact surface thereof, within plus or minus 5% of the length of the contact surfaces of the radially outer first roller (1B).