Ball-Guided Cage Manufacturing for High-Speed Bearings
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Solution Overview
Problem
Shoulder-guided snap cages in radial ball bearings experience high dynamic frictional torque and temperature increase due to sliding contact with inner and outer ring shoulders, leading to reduced service life, especially in high-speed applications like dental turbines where lubrication issues exacerbate abrasive wear.
Innovation Solution
A method for manufacturing ball-guided snap cages using a cutting tool to create cylindrical spherical caps with snap edges, allowing the cage to be guided closely over the balls, reducing friction torque and heat generation, and enabling the use of high-performance materials previously difficult to injection mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If shoulder-guided cage design is used, then the cage can be manufactured by machining, but the dynamic frictional torque increases significantly due to sliding contact with inner and outer ring shoulders
Solution Approach 1:
The invention extracts the harmful sliding contact function from the cage design by removing the shoulder guidance feature. The cage is designed to be guided solely by the balls, eliminating the counterbore and shoulder contact surfaces that cause high friction. This separates the guidance function (performed by balls) from the cage structure, allowing the cage to float without contacting the ring shoulders.
2Ease of manufacture
If shoulder-guided cage design is used, then the cage can be manufactured by machining, but the temperature inside the bearing increases due to friction
Solution Approach 1:
The harmful heat-generating sliding contact is extracted from the system by eliminating the shoulder guidance feature. The cage design removes the counterbore and any surfaces that would contact the inner and outer ring shoulders, thereby eliminating the source of frictional heating while maintaining manufacturability through machining.
3Reliability
If injection molding is used for ball-guided cages, then ball guidance is achieved, but shape tolerances are many times higher than in machining
Solution Approach 1:
The invention replaces the injection molding process with a mechanical machining process (CNC turning). This substitution allows the use of conventional machining methods to create the spherical caps with high precision, eliminating the tolerance issues inherent in injection molding while maintaining the ball-guided design features.
4Reliability
If injection molding is used for ball-guided cages, then ball guidance is achieved, but injection points cause unacceptable imbalance properties in high-speed applications
Solution Approach 1:
The invention replaces the injection molding process with mechanical machining, thereby eliminating the injection points and associated imbalance issues. The machining process allows for symmetric tool path generation that creates balanced spherical caps without the material accumulation and voids characteristic of injection molding, making the cage suitable for high-speed applications.
5Strength
If cotton fabric-reinforced phenolic resin is used, then high-performance material properties are achieved, but the material cannot be injection molded
Solution Approach 1:
The invention replaces the injection molding manufacturing method with mechanical machining (CNC turning). This substitution enables the use of cotton fabric-reinforced phenolic resin and other high-performance materials that cannot be injection molded, while still achieving the required spherical cap geometry and ball-guided functionality through precise machining operations.
6Strength
If polyamidimide is injection molded, then material properties are achieved, but dimensional and shape tolerances cannot be controlled due to shrinkage from tempering
Solution Approach 1:
The invention replaces injection molding with mechanical machining, thereby eliminating the uncontrolled shrinkage and tolerance issues associated with polyamidimide tempering. The machining process allows for precise control of dimensional and shape tolerances in the spherical caps, while still enabling the use of polyamidimide and other high-performance materials that require post-molding heat treatment.
Data Source
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AI summary
The present invention relates to a method for producing a ball-guided snap-action cage (16, 30, 32) for ball bearings having the following steps: - provision of a semi-finished product with a circularly annular end section or of an annular blank; - provision of a cutting tool (34) which has a continuous blade (35), comprising a part (36) which projects at the free end (38) of the cutting tool (34) and a shank (37) which is set back with respect to the former; - production of at least one ball pocket (18) by means of the cutting tool (34), comprising a substantially cylindrical spherical cap (20) and at least one snap-action edge (22) which covers the spherical cap (20) partially, wherein the production of the ball pocket (18) comprises the following steps: - lowering of the rotating cutting tool (34) in the axial direction of the circularly annular end section or of the annular blank as far as a dimension b below the upper edge of the circularly annular end section or of the annular blank, wherein the rotation centre point of the cutting tool (34) is offset by a dimension a from a predefinable spherical-cap centre point transversely with respect to the axial direction of the circularly annular end section or of the annular blank; - moving of the rotating cutting tool (34) transversely with respect to the axial direction of the circularly annular end section or of the annular blank by the dimension a, in such a way that the rotation centre point of the cutting tool (34) and the predefinable spherical-cap centre point coincide; - further lowering of the rotating cutting tool (34) in the axial direction of the circularly annular end section or the annular blank by a dimension c with the formation of the spherical cap (20).