Outer Ring Track Surface Precision for Needle Roller Bearing Stability
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Solution Overview
Problem
Drawn cup needle roller bearings used in engine applications experience instability and seizing due to inadequate precision in the outer ring's track surface, leading to suboptimal roller guidance and contact, which affects the anti-seizing properties of piston pin and crankshaft supporting structures in 2-cycle engines.
Innovation Solution
The outer ring is press-fitted with a straightness of no more than 0.008mm and parallelism of no more than 0.015mm, combined with a retainer featuring a sheared surface for guiding rollers, ensuring stable roller contact and reduced seizing risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for the outer ring track surface, then manufacturing cost and time are reduced, but the straightness and parallelism precision are insufficient leading to roller instability
Solution Approach 1:
The patent applies preliminary action by pre-establishing a highly precise reference ring with predetermined straightness (0.008mm or less) and parallelism (0.015mm or less) before manufacturing the outer ring. This reference ring serves as a master template that guides the subsequent outer ring fabrication, ensuring the track surface achieves the required precision without requiring complex manufacturing processes for each individual outer ring.
Solution Approach 2:
The reference ring acts as an intermediary element between the manufacturing process and the final outer ring product. It mediates the transfer of precision requirements by providing a physical reference surface that the outer ring is manufactured against, thereby indirectly achieving high precision track surfaces while simplifying the direct manufacturing complexity.
2Reliability
If the outer ring track surface precision is increased to 0.008mm straightness and 0.015mm parallelism, then roller stability and anti-seizing properties are improved, but manufacturing difficulty and cost increase
Solution Approach 1:
The reference ring is manufactured in advance with the extreme precision requirements (0.008mm straightness, 0.015mm parallelism) so that these difficult-to-achieve tolerances are established once in a master component rather than repeatedly in each outer ring. This preliminary creation of the precision standard reduces the overall manufacturing difficulty.
Solution Approach 2:
The reference ring serves as an intermediary that absorbs the manufacturing difficulty of achieving high precision. By manufacturing the precision reference once and using it as a template for multiple outer rings, the patent transforms a repeatedly difficult task into a single difficult task followed by easier replication processes.
3Productivity
If the track surface precision is insufficient, then manufacturing is easier and faster, but roller guidance becomes unstable causing seizing
Solution Approach 1:
The precise reference ring is prepared in advance to establish the quality standard before production begins. This preliminary precision foundation enables rapid outer ring manufacturing while ensuring that even quickly produced components meet the reliability requirements for roller stability.
Solution Approach 2:
The reference ring acts as a mediating quality assurance tool that allows fast manufacturing processes to still produce reliable results. By providing a physical precision template, it mediates between the speed of production and the quality of the output, enabling both high productivity and roller stability.
Data Source
Figure 1
Figure 2
Figure 3A~3E
AI summary
The straightness and parallelism of a track surface on which rollers (23) roll are measured within a range "L2" as a range for measuring the straightness and parallelism. The range"L2" is a range such that L2 . 0.8 × L when a roller length is "L". When the dimension from the corner P of the flange (29) on the inner diameter side to the starting point of the range "L2" is "L1", the dimension "L1" is ranged such that 0.8mm . L1 . 2mm. In this range, the straightness of the track surface of the outer ring (22) in the axial direction is not more than 0.008mm and the parallelism thereof is not more than 0.015mm.