Thin-Ring Bearing Raceway Cladding for Cost-Accurate CT Rotation
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Solution Overview
Problem
Existing thin-section bearings for computed tomography scanners are costly due to the use of high-purity steel grades, necessitating expensive materials and heat treatments for high running accuracy and smooth operation.
Innovation Solution
A thin-section bearing with an inner diameter greater than 700 mm, comprising an unhardened metallic base material with a hardness of less than 60 HRC, partially covered by a functional layer of high hardness (60 HRC) applied via laser cladding, where the functional layer thickness varies and is minimized to cover only raceway contact areas, using materials like steel grade 1.3344 or tungsten carbide in a nickel binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-purity steel grades are used for bearing rings, then high running accuracy and smooth operation are achieved, but manufacturing costs increase significantly
Solution Approach 1:
The patent applies different material qualities to different regions of the bearing ring. The functional layer (0.5-3 mm thick) made of high-purity, high-hardness material (60 HRC or higher) is applied only to the raceway receiving surfaces where rolling elements contact, while the base material can be lower purity and hardness. This localized application of high-quality material achieves the required running accuracy and smooth operation only where needed, significantly reducing overall material costs compared to using high-purity steel throughout the entire bearing ring.
Solution Approach 2:
The patent creates a composite structure consisting of a base material (unalloyed steel or cast iron) combined with a functional layer (alloy steel or hard metal coating). This composite construction allows the bearing to achieve high running accuracy through the hard, smooth functional layer while the base material provides structural support at lower cost. The functional layer is applied via welding, brazing, or bonding processes, creating a durable composite component that resolves the contradiction between performance and manufacturing cost.
2Reliability
If the entire bearing ring is heat treated to high hardness, then roll resistance is improved, but stresses and distortion increase
Solution Approach 1:
The patent applies heat treatment or hardening only to the functional layer on the raceway surfaces, not to the entire bearing ring. The functional layer is hardened to high hardness (60 HRC or higher) to provide excellent roll resistance where the rolling elements contact, while the base material remains in a more ductile state with lower hardness. This localized hardening achieves the required roll resistance without subjecting the entire bearing ring to heat treatment, thereby minimizing induced stresses and distortion.
3Reliability
If functional layer thickness is increased to ensure durability, then roll resistance improves, but manufacturing cost increases
Solution Approach 1:
The patent applies the functional layer with a thickness of 0.5 to 3 mm, which is sufficient to provide the required durability and roll resistance for the bearing application. This thickness is optimized to be thick enough to ensure the functional layer can withstand the contact stresses and provide long service life, but not excessively thick to avoid unnecessary material costs. The functional layer completely covers the raceway receiving surfaces at this optimized thickness, providing adequate protection and performance without over-engineering the material usage.
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
Significantly reduces manufacturing costs by utilizing less expensive base materials and minimizing heat treatment, while maintaining high performance through a durable, roll-resistant functional layer, ensuring smooth operation and cost savings.
Implementation Method 1
a functional layer with a functional layer thickness in the range of 0.5 to 3 mm, wherein the functional layer is formed from a metallic functional layer material with a hardness of at least 60 HRC
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a thin-ring bearing (1), in particular for a computed tomography unit, comprising at least one outer ring (2a, 2b), at least one inner ring (3a, 3b) and a plurality of spherical rolling bodies (4), wherein the at least one inner ring (3a, 3b) is formed with an inside diameter (Di) of greater than 700 mm, wherein the at least one inner ring (3a, 3b) and the at least one outer ring (2a, 2b) are formed from an unhardened metallic base material (6) with a hardness of less than 60 HRC, and wherein the at least one inner ring (3a, 3b) and the at least one outer ring (2a, 2b) each form a raceway receiving surface (5), wherein the base material (6) is at least partially covered with a functional layer (7) of a functional layer thickness in the range from 0.5 to 3 mm in the region of the raceway receiving surfaces (5), wherein the functional layer (7) is formed from a metallic functional layer material with a hardness of at least 60 HRC.