Tapered Roller Bearing Retainer Rigidity via Conical Crossbars
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Solution Overview
Problem
Tapered roller bearings with synthetic resin retainers face challenges in maintaining rigidity, preventing premature deterioration, and ensuring stable rotation due to radial outward loads and stress concentration, leading to potential cracks and breakage, especially in large-diameter applications like construction machines.
Innovation Solution
The retainer is designed with arcuately curved side surfaces, conical surfaces extending parallel to each other, and a small-diameter flange with an inclined surface matching the inner ring's central angle, minimizing deformation and stress, and increasing the crossbar thickness, while maintaining a specific diameter ratio to prevent excessive force on the retainer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the retainer is increased radially outwardly to increase its rigidity, then the rigidity of the retainer is improved, but the retainer may interfere with the raceway of the outer ring
Solution Approach 1:
The retainer crossbars are designed with conical surfaces having a specific inclination angle (greater than the bearing central angle) rather than being purely radial. This angular orientation in a different dimensional direction allows the crossbars to achieve necessary rigidity through their geometric configuration while maintaining adequate clearance from the outer ring raceway, resolving the contradiction between thickness increase and interference prevention.
2Ease of manufacture
If the retainer is made of synthetic resin to reduce weight and cost, then manufacturing cost and weight are reduced, but it is difficult to ensure enough rigidity for large-diameter bearings
Solution Approach 1:
The patent changes the geometric parameters of the retainer crossbars by specifying conical surfaces with inclination angles greater than the bearing central angle. This parameter modification allows synthetic resin retainers to achieve sufficient rigidity for large-diameter bearings without requiring material changes or increased thickness, thereby maintaining cost advantages while improving structural performance.
Solution Approach 2:
The retainer is designed as a composite structure combining synthetic resin material with optimized conical geometric features. The specific angular configuration of the crossbars creates a structurally efficient form that compensates for the lower inherent stiffness of synthetic resin, enabling cost-effective manufacturing while achieving required rigidity levels.
3Reliability
If the maximum outer diameter of the small-diameter flange is increased to prevent separation of tapered rollers, then roller retention is improved, but the retainer is subjected to excessive stress during assembly
Solution Approach 1:
The patent optimizes the dimensional parameters by establishing a specific relationship between the maximum outer diameter of the small-diameter flange and the inscribed circle diameter of the tapered rollers. This parameter optimization ensures adequate roller retention while limiting the radial expansion force applied to the retainer during assembly, preventing excessive stress and potential damage.
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4C
AI summary
A plurality of tapered rollers are retained between an outer ring and an inner ring by a retainer so as to be circumferentially spaced apart from each other. The inner ring is formed with a raceway on its outer surface and includes a small-diameter flange and a large-diameter flange at the small- and large-diameter ends of the raceway, respectively. The retainer includes two annular portions and crossbars extending between the annular portions. Its radially inner surface is located radially inwardly of the pitch cone of the tapered rollers (conical surface defined by the axes of the tapered rollers) to increase the thickness of the crossbars as well as the axial thickness of the small-diameter annular portion. The rigidity of the retainer thus increases. The conical surface defined by the outer surfaces of the crossbars has an inclination angle that is greater than the central angle of the bearing to increase the volume of the crossbars, thereby further increasing the rigidity of the retainer, and also to increase the contact length between the tapered rollers and the crossbars, thereby stabilizing the rotation of the tapered rollers about the axis of the bearing.