Ball Bearing Rivet Hole Geometry for Easier Cage Assembly
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Solution Overview
Problem
The assembly of iron plate rivet crimping cages in ball bearings is challenging due to difficulties in aligning the rivet shafts from the first annular member with the second rivet holes in the second annular member, leading to complex and costly machining processes.
Innovation Solution
The second rivet holes in the second annular member are formed with a cylindrical shear surface and a tapered fracture surface, which acts as a guiding surface for the rivet shafts during assembly, simplifying the insertion process and reducing machining costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional rivet hole formation is used, then manufacturing cost is reduced, but alignment difficulty increases
Solution Approach 1:
The patent applies preliminary action by forming tapered surfaces at the bottom of rivet holes during the initial punching process. These tapered surfaces are created in advance to guide rivet shaft alignment, eliminating the need for separate alignment operations and reducing overall manufacturing complexity while improving assembly ease.
Solution Approach 2:
The tapered surface acts as an intermediary element between the rivet shaft and the rivet hole. This intermediate geometric feature facilitates the transition from misaligned states to properly aligned states, enabling easy insertion and alignment without requiring precise initial positioning or additional alignment machinery.
2Ease of operation
If tapered chamfers are formed at rivet holes to improve alignment, then ease of assembly is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the chamfer formation operation with the rivet hole punching operation. The tapered surface is created as an integrated feature during the single punching step, combining what would traditionally be separate machining operations into one process, thereby reducing manufacturing cost while maintaining the alignment benefits of tapered chamfers.
Solution Approach 2:
The patent changes the geometric parameters of the rivet hole by incorporating a tapered surface with a specific angle (5-15 degrees). This parameter modification enables the hole to serve dual functions: receiving the rivet and providing alignment guidance, thereby achieving improved assembly ease without adding separate alignment features that would increase manufacturing cost.
3Strength
If precise alignment is required for rivet insertion, then connection strength is improved, but assembly time increases
Solution Approach 1:
The patent applies self-service by designing the rivet hole with an integrated tapered surface that automatically performs the alignment function. The tapered geometry causes the rivet shaft to self-align during insertion without requiring external alignment tools or operators to perform precise positioning, thereby maintaining connection strength while dramatically reducing assembly time.
Data Source
AI summary
Each second rivet hole has an inner periphery constituted by a cylindrical shear surface having a constant inner diameter that does not axially change; and a tapered fracture surface gradually radially expanding from the shear surface toward an abutment surface.