Roller Circle Assembly Tapered Roller Inversion
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Solution Overview
Problem
Heavy earth-moving equipment experiences highly concentrated stresses and costly failures due to misalignment and non-uniform loading in roller circle assemblies, which are exacerbated by the use of tapered rollers and inclined surfaces that lead to twisting and distortion under dynamic loads.
Innovation Solution
A roller-circle assembly design featuring a lower rail with an inclined surface and an upper rail with a substantially planar surface perpendicular to the axis, supported by tapered rollers that engage both surfaces, reducing the overturning moment and distributing loads more uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tapered rollers with inclined surfaces are used in the roller circle assembly, then the rollers can support heavy loads and facilitate rotation, but the rollers twist and distort under dynamic non-uniform loading, concentrating stresses on small contact areas and causing costly failures
Solution Approach 1:
The patent inverts the conventional tapered roller configuration by using a cylindrical roller with a flat top surface instead of a tapered roller with an inclined surface. This inversion changes the contact mechanics from point/line contact on inclined surfaces to face contact on a flat surface, eliminating the twisting and distorting forces that cause roller failure under dynamic loading while maintaining the ability to support heavy radial loads.
2Ease of manufacture
If a gap around the lifting pin is created for built-in tolerance, then the upper structure can be assembled, but misalignment between the upper and lower structures occurs, contributing to highly concentrated stresses on the bearing assembly
Solution Approach 1:
The cylindrical roller with a flat top surface acts as an intermediary element between the upper and lower structures. This intermediary design provides a stable, non-twisting contact surface that maintains alignment even with the presence of gaps for tolerance, distributing the alignment errors uniformly across the roller circumference rather than concentrating stresses at point contacts on inclined surfaces.
3Force
If conventional tapered rollers are used in the roller circle assembly, then the structure can support very heavy loads of several hundred metric tons, but the loading along the arc length becomes non-uniform during operations, causing rollers to twist and distort relative to the rails
Solution Approach 1:
The patent changes the geometric parameters of the roller from a tapered shape with an inclined surface to a cylindrical shape with a flat top surface. This parameter change transforms the contact characteristics from line contact on an angle to face contact on a plane, enabling the roller to withstand non-uniform dynamic loading without twisting or distorting while maintaining the capacity to support very heavy loads of several hundred metric tons.
Data Source
AI summary
A heavy earth-moving machine having a lower structure and an upper structure rotatably supported by the lower structure for rotation about an axis. A substantially circular lower rail is mounted on the lower structure and includes an inclined lower surface. A substantially circular upper rail is mounted on the upper structure and includes a substantially planar upper surface that is oriented substantially perpendicular to the axis. Tapered rollers support the upper rail above the lower rail for rotation of the upper rail about the axis. Each roller engages both the upper surface and the lower surface and defines and rotates about a roller axis that intersects the axis at a non-perpendicular angle.