Floating Seal Bearing Assembly for Welded Bracket Tolerance
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Solution Overview
Problem
In construction machines, especially front working machines with welded structures, achieving precise dimensional accuracy for mounting surfaces is challenging due to thermal distortion, leading to inadequate sealing performance of floating seals, which requires additional lubrication and maintenance.
Innovation Solution
A bearing device design that includes a shaft body, cylindrical parts, and holding members with a pin to apply a predetermined axial load to a seal member, ensuring sealing performance without the need for long-term lubrication, featuring a sandwiched seal member between cylinder and holding parts, and reinforced structures to prevent contamination and maintain axial load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a floating seal is used to encapsulate grease in a lubricating part, then the sealing performance is improved, but the dimensional precision between brackets must be high to ensure the initial axial compressive load is applied correctly
Solution Approach 1:
A positioning member (dowel pin) is introduced as an intermediary element between the first and second brackets to establish precise relative positioning. This mediator component ensures the correct initial axial compressive load is applied to the floating seal without requiring high dimensional precision in the brackets themselves, resolving the contradiction between sealing performance and manufacturing precision
Solution Approach 2:
The floating seal structure is designed to automatically generate the necessary initial axial compressive load through its own weight and elastic deformation when installed. The seal member's flexibility allows it to self-adjust and apply the required preload without external intervention, maintaining sealing performance while reducing requirements for precise bracket dimensions
2Ease of manufacture
If the dimension between brackets is wider than supposed, then the assembly is easier to manufacture, but the compressive load on the floating seal is insufficient and sealing performance deteriorates
Solution Approach 1:
The positioning member acts as a mediator that compensates for dimensional variations in the brackets. By providing a fixed reference dimension through the positioning member itself rather than relying on bracket dimensions, the system maintains consistent compressive load on the seal while allowing broader manufacturing tolerances for the brackets
Solution Approach 2:
The design changes the critical dimension from the bracket-to-bracket distance to the positioning member length. This parameter substitution allows the critical dimensional control to be concentrated in a single, easily manufactured component (the positioning member) rather than being distributed across multiple brackets with cumulative tolerances
3Ease of manufacture
If welding is used to create the front working machine structure, then the manufacturing process is simplified, but thermal distortion occurs making it difficult to obtain correct finished dimensions
Solution Approach 1:
The structure is divided into separate components (first bracket, second bracket, positioning member) that can be manufactured and heat-treated independently before final assembly. This segmentation allows each component to be processed without the thermal distortion problems of large-scale welding, while the final assembly uses the positioning member to ensure precise relative positioning
Solution Approach 2:
The positioning member serves as a mediator that decouples the dimensional accuracy requirement from the welded structure. By providing a separate, precisely manufactured reference element, the system achieves correct finished dimensions without requiring the welded brackets themselves to have high dimensional accuracy
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
Ensures reliable sealing performance and eliminates the need for periodic lubrication, maintaining the bearing's functionality over a long term while maintaining dimensional precision and preventing contamination, thus reducing maintenance costs.
Implementation Method 1
a pin being inserted into insertion holes provided in the shaft body and holding member and integrally fixing the holding member and shaft body at a position where a predetermined axial load is applied to the seal member
Data Source
AI summary
To provide a bearing device which can ensure the sealing performance by using floating seal to eliminate the need of adding lubricant over a long term and a construction machine comprising the bearing device. The bearing device comprises a shaft. The bearing device comprises a boss portion having a bearing rotatably holding the shaft. The bearing device comprises a cylindrical collar mounted on an end part side of the shaft rather than the boss portion. The bearing device comprises a floating seal for sealing lubricant sandwiched between the boss portion and collar. The bearing device comprises a pin being inserted into the insertion holes provided in the shaft and collar and integrally fixing the shaft and collar at a position where a predetermined axial load is applied to the floating seal between the collar and boss portion. The bearing device comprises a bracket having an opening for mounting the collar.