Cross Roller Bearing Plug Geometry to Prevent Bolt Loosening
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Solution Overview
Problem
Cross roller bearings used in devices experience instability due to repeated loading on the blocking plug, leading to rattling and loosening of the bolt, which affects the stable operation of the bearing.
Innovation Solution
The bearing design includes a blocking plug with a plug body having a bolt insertion hole and a mating surface that overlaps the bottom surface of the insertion groove, where the shortest lengths between the bolt insertion hole and the raceway surfaces satisfy the formula La/Lb > 0.65, ensuring tight contact and minimizing rattling and bolt loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the blocking plug is secured with a bolt in the insertion groove, then the rolling elements can be inserted and the bearing can operate, but the repeated loading causes rattling of the blocking plug and loosening of the bolt
Solution Approach 1:
The patent applies local quality by creating an asymmetric geometry in the blocking plug where the distance from the bolt insertion hole to the inner raceway surface (La) is made significantly larger than the distance to the outer raceway surface (Lb), with La/Lb > 0.65. This local geometric modification ensures that the contact surface between the blocking plug and insertion groove bottom is positioned optimally to resist repeated loading forces, preventing rattling and bolt loosening while maintaining ease of assembly
2Reliability
If the blocking plug is tightly contacted with the bottom surface of the insertion groove, then rattling is minimized, but the bolt insertion hole position must be precisely controlled
Solution Approach 1:
The patent employs parameter changes by establishing a specific geometric relationship La/Lb > 0.65 for the blocking plug dimensions. This parameter specification allows the contact surface to be optimally positioned to minimize rattling under repeated loading. The asymmetric design with clearly defined dimensional relationships simplifies manufacturing control compared to requiring precise positioning of the bolt insertion hole alone, as the La and Lb dimensions can be controlled independently during manufacturing
Data Source
AI summary
One aspect of the present disclosure provides a first bearing including an inner ring, an outer ring, and cylindrical rollers. The inner ring includes: an insertion groove formed in a lower surface for inserting the cylindrical rollers between an inner raceway surface and an outer raceway surface; a blocking plug configured to block the insertion groove, the blocking plug having a part of the inner raceway surface formed thereon; and a bolt for securing the blocking plug in the insertion groove. In the mating surface of the blocking plug contacted with the bottom surface of the insertion groove, when the shortest length between the bolt insertion hole and the inner raceway surface is shown as La, and the shortest length between the bolt insertion hole and the inner peripheral surface is shown as Lb, the shortest lengths La and Lb satisfy the following formula: La/Lb>0.65.