Shell-Type Radial Needle Bearing Outer Ring Fatigue Strength
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Solution Overview
Problem
The existing shell-type radial needle bearings for universal joints face challenges in maintaining fatigue strength, preventing outer ring displacement, and resisting corrosion without increasing the outer ring's size or complexity, which complicates manufacturing and increases costs.
Innovation Solution
The outer ring features a cylindrical section with an outer raceway and a bottom plate section, where residual compressive stress is induced in the surface layer, improving fatigue strength and adhesion of anti-corrosion coatings, while shot peening enhances surface roughness to prevent displacement and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the bottom plate section is increased to improve fatigue strength, then the fatigue strength is improved, but the outer ring size increases
Solution Approach 1:
The patent applies shot peening treatment to change the physical state of the surface layer, inducing residual compressive stress without changing the geometric dimensions of the outer ring. This allows fatigue strength to be improved while maintaining the original size constraints.
Solution Approach 2:
The shot peening treatment is applied in advance during manufacturing to pre-induce residual compressive stress in the surface layer before the bearing is assembled and put into service. This preliminary action ensures the fatigue strength is enhanced before the component experiences operational loads.
2Strength
If shot peening is applied to improve fatigue strength, then the fatigue strength is improved, but the manufacturing process complexity increases
Solution Approach 1:
The shot peening process is combined with the existing manufacturing workflow of the outer ring, integrating it as a standard surface treatment step. This merging approach allows the fatigue strength improvement to be achieved without requiring separate, complex manufacturing systems.
3Reliability
If shot peening is applied to enhance surface roughness for anti-corrosion coating adhesion, then the coating adhesion is improved, but the manufacturing process complexity increases
Solution Approach 1:
The shot peening process simultaneously achieves multiple objectives: it induces residual compressive stress for fatigue strength improvement and creates surface roughness for enhanced coating adhesion. This single merged process eliminates the need for separate treatments, reducing manufacturing complexity while improving both fatigue strength and corrosion resistance.
Solution Approach 2:
The shot peening treatment serves multiple functions: it strengthens the surface against fatigue, creates anchorage profiles for coatings, and cleans the surface. This multi-functional approach allows a single process to address multiple requirements without increasing overall manufacturing complexity.
4Strength
If the outer ring size is increased to improve fatigue strength, then the fatigue strength is improved, but the assembly ease deteriorates
Solution Approach 1:
The patent changes the stress state parameter of the surface layer through shot peening, inducing residual compressive stress. This allows fatigue strength to be improved without changing the dimensional parameters of the outer ring, thereby maintaining ease of assembly.
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
This solution enhances the fatigue strength and corrosion resistance of the outer ring without increasing its size or complexity, improving assembly ease and reducing manufacturing costs by inducing residual compressive stress and optimizing surface characteristics.
Implementation Method 1
performing shot peening of the intermediate raw material to thereby obtain the outer ring having: residual compressive stress in a surface layer section on an outer surface side of the cylindrical section and the bottom plate section
Implementation Method 2
the outer ring has: residual compressive stress in a surface layer section on an outer surface side of the cylindrical section and the bottom plate section
Data Source
AI summary
An outer ring 6a for a shell-type radial needle bearing having a cylindrical shape with a bottom is achieved for which fatigue life of the bottom plate section 9a and the continuous section between the bottom plate section 9a and the cylindrical section 8a is improved, as well as the anti-corrosion characteristic of the outer ring 6a is improved and the outer ring 6a can be prevented from coming out of the bearing without an increase in cost. After obtaining an intermediate raw material 35 having a cylindrical section and a bottom plate section from a metal raw material, shot peening is performed on the intermediate material 35 to create residual compressive stress in the surface and surface layer section on the outer surface side of the cylindrical section 8a and the bottom plate section 9a such that the residual compressive stress in the surface layer section on the outer surface side is greater than the in the surface layer section on the inner surface side, and from the surface to a depth of 0.03 mm is 700 MPa to 1600 MPa.