Rivet Geometry for Ribbon Cage Joint Strength
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Solution Overview
Problem
The existing manufacturing methods for ribbon cages in ball bearings face challenges in maintaining joint section characteristics between cage elements due to volume variations in rivets, leading to issues like gaps, insufficient strength, and burrs, which affect the performance and durability of the ball bearing, while strict manufacturing tolerances increase production costs.
Innovation Solution
A manufacturing method for ribbon cages that involves a pair of circular-ring shaped cage elements with flat and semi-circular sections, using rivets with specific flange and convex sections that are plastically deformed to ensure proper contact and strength, regardless of rivet volume variations, by adjusting the crimping dies' stroke to maintain optimal thickness and prevent burr formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strict manufacturing tolerances are applied to rivets to ensure good joint characteristics, then joint strength and precision are improved, but manufacturing cost increases
Solution Approach 1:
The invention changes the geometric parameters of the rivet by adding a tapered section with a specific angle (α) between 15-45 degrees. This parameter change allows the rivet to accommodate volume variations while maintaining joint characteristics, resolving the contradiction between precision and manufacturing cost.
Solution Approach 2:
The tapered section is pre-formed on the rivet before assembly. This preliminary action ensures that when the rivet is inserted into the hole, the tapered geometry automatically compensates for volume variations, eliminating the need for strict tolerance control during manufacturing.
2Ease of manufacture
If rivet volume varies due to loose tolerances to reduce cost, then manufacturing cost decreases, but joint characteristics deteriorate with gaps and insufficient strength
Solution Approach 1:
The tapered section geometry (with angle α between 15-45 degrees) transforms the effect of volume variations. Instead of causing gaps or insufficient strength, the tapered shape ensures proper contact between the rivet head and the workpiece even when rivet volumes vary, maintaining joint strength without increasing cost.
3Ease of manufacture
If rivet volume varies to reduce manufacturing cost, then production cost decreases, but harmful factors increase with burr formation
Solution Approach 1:
The tapered section angle (α between 15-45 degrees) is specifically designed to control the deformation behavior during crimping. This parameter change ensures that material flow is controlled smoothly, preventing burr formation even when rivet volumes vary, thus eliminating harmful factors while maintaining low manufacturing cost.
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 method ensures good joint characteristics and maintains strength and rigidity, preventing gaps and burrs, even with varying rivet volumes, thus enhancing the durability and performance of the ball bearing without increasing manufacturing costs.
Implementation Method 1
the tip-end sections of the rod sections are pressed in the axial direction by the other crimping die to plastically deform the tip-end sections of the rod sections and the head sections of the rivets
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3~4
AI summary
Characteristics of joint sections using rivets 11a that join flat sections 12a, 12b of a pair of cage elements are improved regardless of differences in the volumes of the rivets 11a. A head section 16a and a crimped section 19a of a rivet 11a comprise flange sections 23a, 23b and convex sections 24a, 24b The inside surfaces of the flange sections 23a, 23b press against the outside surfaces of the flat sections 12a, 12b. The convex sections 24a, 24b have a truncated cone shape with the maximum diameter being on the flange section 23a, 23b side. The diameter d24 of the apex of the convex sections 24a, 24b is equal to or less than the inner diameter R15 of circular holes 15, and the outer diameter D23 of the flange sections 23a, 23b is equal to or greater than the outer diameter D24 of the bottom section of the convex sections 24a, 24b Furthermore, the amount of protrusion L23 that the flange sections 23a, 23b protrude from the convex sections 24a, 24b is equal to or less than two times the thickness T23 in the axial direction of the flange sections 23a, 23b.