Bearing Cage Inserts to Prevent Deformation at High Speed
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Solution Overview
Problem
Conventional bearing unit cages made of polymer materials fail to retain rolling bodies effectively at high speeds and high temperatures, leading to deformation, potential expulsion, and loss of function due to centrifugal forces and thermal expansion.
Innovation Solution
A polymer-based retention device with inserts that snap-fit into the cage fingers, providing oblique surfaces to absorb stresses and prevent deformation, ensuring the cage maintains its shape and retention capability at high speeds and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer cages are used, then the bearing unit can operate at low speeds and temperatures, but the cage deforms and loses retention capability at high speeds and temperatures
Solution Approach 1:
The invention combines polymer material with metallic inserts to create a composite cage structure. The polymer provides lightweight, low-noise operation while the metallic inserts provide high strength and dimensional stability at high speeds and temperatures, resolving the contradiction between retention reliability and operational speed
Solution Approach 2:
The cage is segmented into multiple components: the polymer cage body and separate metallic inserts that are coupled together. This segmentation allows each component to perform its optimal function - the polymer cage maintains low noise and light weight, while the metallic inserts provide the necessary structural rigidity to prevent deformation at high speeds
2Object-generated harmful factors
If conventional polymer cages are used, then the bearing unit can operate quietly, but the cage becomes noisy when made of metallic materials
Solution Approach 1:
The invention applies local quality by using polymer material for the main cage body where quiet operation is needed, and selectively adding metallic inserts only in critical areas where high strength and thermal stability are required for retention capability, thus achieving both low noise and high reliability
3Reliability
If metallic materials are used for the cage, then retention capability improves, but the cost increases significantly
Solution Approach 1:
The composite structure uses inexpensive polymer material as the base and adds small, strategically placed metallic inserts. This approach achieves the retention capability of metallic cages while keeping the overall material cost much lower than a fully metallic cage, resolving the contradiction between reliability and manufacturing cost
4Speed
If the cage fingers are allowed to open under centrifugal force, then the cage can accommodate high speed, but the retention of rolling bodies is reduced
Solution Approach 1:
The metallic inserts are pre-installed in the cage fingers to provide counteracting force against centrifugal forces before the bearing operates at high speed. This preliminary reinforcement prevents the fingers from opening under operational centrifugal load, maintaining both high speed capability and rolling body retention
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 retention device effectively maintains the cage's structural integrity and retention of rolling bodies at high speeds and temperatures, preventing deformation and noise issues associated with metal cages, allowing for reliable operation up to 30000 rev/min and 150°C without dislodging or rubbing against the outer ring.
Implementation Method 1
at high speeds (for example, for rotary speeds close to 20000 rev/min), owing to the centrifugal force, the fingers forming the cavities for housing the balls tend to 'open up' which lessens the retention of the balls
Implementation Method 2
A similar problem arises due to high operating temperatures, or through the combined effect of high speed and high temperature. For example, in conditions with a rotary speed close to 20000 rev/min and temperatures around 150° C., the radial deformation of the cage is of such an extent that the cage will rub against the radially outer ring of the bearing unit
Data Source
AI summary
A bearing unit includes a radially outer ring, a radially inner ring, a row of rolling bodies interposed between the radially outer ring and the radially inner ring and a cage for retaining the rolling bodies, where the cage includes a rib with a circular base and a plurality of circumferentially spaced fingers defining a plurality of pockets for holding the respective rolling bodies of the row of rolling bodies. Also, a plurality of inserts formed separately from the cage, each of the plurality of inserts being inserted inside seats of corresponding adjacent pairs of fingers of the plurality of fingers to limit circumferential deformation of the fingers.