Inner Bearing Ring Geometry for Uniform Shoulder Grinding
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Solution Overview
Problem
The existing bearing units with clamping elements for locking the radially inner ring onto a rotating shaft face issues with non-uniform grinding due to the presence of threaded holes for grub screws, leading to asymmetric force distribution and material removal, resulting in parts rejection during quality control.
Innovation Solution
Designing a radially inner ring with two different diameters for the shoulder, where the portion with threaded holes has a smaller diameter to avoid grinding and the remainder has a uniform diameter for precise grinding, ensuring consistent material removal and reducing part rejections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded holes for grub screws are present in the radially inner ring, then the ring can be locked onto the rotating shaft, but non-uniform grinding occurs due to asymmetric force distribution
Solution Approach 1:
The radially inner ring is segmented into two distinct portions: a first portion containing threaded holes for locking capability, and a second portion with uniform geometry for precise grinding. This segmentation allows each portion to fulfill its specific function without compromising the other, resolving the contradiction between locking reliability and grinding uniformity
Solution Approach 2:
Different portions of the radially inner ring are assigned different geometric properties: the first portion has a specific diameter adapted for grub screw locking, while the second portion has a uniform diameter optimized for grinding. This local differentiation enables simultaneous achievement of reliable locking and precise manufacturing
2Productivity
If solid profile grinding is used on the shoulder diameter, then efficient material removal is achieved, but non-uniform surface finish results due to holes modifying ring rigidity
Solution Approach 1:
The problematic threaded holes are extracted from the grinding zone by placing them exclusively in the first portion of the ring. This separation removes the source of asymmetric force distribution from the grinding process, allowing solid profile grinding to achieve uniform surface finish on the second portion without the detrimental effects of hole-induced rigidity variations
3Ease of manufacture
If headless screws are used for clamping, then simpler and more economical locking is achieved, but non-uniform grinding of the shoulder diameter occurs
Solution Approach 1:
The ring is divided into a first portion for simplified headless screw locking and a second portion for precise uniform grinding. This spatial segmentation allows the economical locking solution to coexist with high-precision manufacturing requirements by ensuring the screws only engage with the first portion during the grinding process
Data Source
AI summary
A bearing unit having a stationary radially outer ring; a radially inner ring rotatable around a central rotation axis (X) of the bearing unit and provided with at least one raceway and, in a terminal portion thereof, with at least one through hole; at least one row of rolling elements interposed between the radially outer ring and the radially inner ring; and at least one clamping element, which is accommodated in the through hole, to lock the radially inner ring on to a rotating shaft. A first radially outer cylindrical surface of the terminal portion of the radially inner ring has a diameter smaller than the diameter of a second radially outer cylindrical surface of a second terminal portion of the radially inner ring.