Tapered Roller Bearing Assembly With Straight Rollers to Reduce End Loading
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Solution Overview
Problem
Tapered roller bearing assemblies are difficult and expensive to manufacture due to their complex geometry, and straight roller bearing assemblies experience undesirable end loading and stress profiles leading to premature failure when subjected to rotation.
Innovation Solution
A roller bearing assembly utilizing a tapered inner and outer cup with a convex outer raceway and straight rollers, where each straight roller is disposed between the cups and has a cylindrical body, allowing for rolling contact along the entire length and limited rotation to reduce end loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tapered rollers are used in the bearing assembly, then the bearing can handle both axial and radial loads effectively, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
Instead of using tapered rollers to achieve the desired load handling, the patent inverts the approach by using straight cylindrical rollers with tapered raceways. This inversion maintains the functional equivalence of handling axial and radial loads while dramatically simplifying the roller geometry to a basic cylindrical shape that is much easier and cheaper to manufacture.
Solution Approach 2:
The patent applies local quality by concentrating the complexity in the raceway geometry rather than the roller geometry. The tapered raceways on the inner and outer rings provide the necessary load distribution characteristics, while the rollers remain simple cylindrical shapes. This localized complexity approach separates the functional requirements from the manufacturing complexity.
2Ease of manufacture
If straight rollers are used in the bearing assembly, then the manufacturing cost and complexity are reduced, but the rollers experience undesirable end loading and stress profiles leading to premature failure
Solution Approach 1:
The patent uses tapered raceways on the inner and outer rings to create a localized stress distribution pattern that directs loads through the midsection of the straight rollers rather than their ends. This localized geometric modification of the raceways protects the simple cylindrical rollers from end loading stresses that would otherwise cause premature failure.
Solution Approach 2:
The patent introduces the taper angle as an additional geometric dimension in the raceway design. This taper dimension transforms the load distribution from a radial-only pattern to a combined radial-axial pattern, redirecting stresses away from the roller ends and through the stronger midsection of the rollers.
3Ease of operation
If straight rollers rotate about their pivot axis during operation, then rolling contact is maintained, but end loading occurs causing spalling and bearing failure
Solution Approach 1:
The tapered raceway geometry introduces an angular dimension to the contact interface. As rollers rotate, the taper angle ensures that the contact point moves along the tapered surface in a way that maintains rolling contact while directing forces through the roller's stronger midsection, preventing the end loading that causes spalling.
Solution Approach 2:
The tapered raceway surfaces provide a curved contact path that guides the rollers through their rotation. This curvature in the raceway geometry ensures smooth rolling contact while the taper directs the contact forces away from the roller ends, eliminating the harmful end loading effect.
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
The design reduces end loading on straight rollers, minimizing spalling and extending the bearing's lifespan by maintaining contact with the outer raceway as the rollers rotate, thus improving the manufacturing efficiency and performance of the bearing assembly.
Implementation Method 1
each straight roller is in rolling contact with the inner raceway and the outer raceway
Data Source
AI summary
A roller bearing assembly including an tapered inner cup defining an inner raceway, an tapered outer cup defining an outer raceway, the outer raceway having a convex profile, the convex profile being defined by an intersection of the outer raceway and a central plane in which a longitudinal center axis of the roller bearing assembly lies, and a plurality of straight rollers disposed between the tapered inner cup and the tapered outer cup so that each straight roller is in rolling contact with the inner raceway and the outer raceway, each straight roller having a first end face, a second end face and a cylindrical body extending therebetween.