Linear Motion Guide Unit Oblique Return Passages
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Solution Overview
Problem
Existing linear motion guide units face challenges in maintaining lubrication without maintenance, especially when miniaturized for high load capacity applications, as they struggle to effectively supply lubricant to rolling elements while preventing leakage.
Innovation Solution
A linear motion guide unit design featuring obliquely positioned return passages within the carriage, end caps with spigots and lubricating ports, and tubular members of porous structure to retain and distribute lubricant, ensuring positive lubrication without leakage, even when the slider is compact in width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the return passages are made horizontally in parallel with load-carrying races at sidewise faraway areas, then the rolling elements can transfer smoothly, but the slider becomes larger in widthwise measurement
Solution Approach 1:
The return passages are repositioned from horizontal parallel arrangement to an oblique upward arrangement relative to the load-carrying races. This dimensional change in passage orientation allows the passages to be closer to the races (distance ≤ 2× rolling element diameter) while maintaining smooth rolling element transfer, thereby reducing the slider's width without compromising operational smoothness
2Force
If the slider is miniaturized with larger rolling elements for high load capacity, then the load capacity increases, but it becomes challenging to supply lubricant continuously without maintenance
Solution Approach 1:
The end caps are constructed from sintered resinous material with cellular texture, creating a porous structure that absorbs and retains lubricant within its matrix. This porous material allows continuous lubricant supply to the rolling elements through capillary action and controlled release, ensuring maintenance-free operation even in miniaturized high-load applications
Solution Approach 2:
The end caps are pre-filled with lubricant during manufacturing, storing an adequate amount of lubricant within the porous cellular structure before the slider begins operation. This preliminary lubricant loading ensures continuous lubrication is available from the start without requiring external maintenance or replenishment
3Reliability
If tubular connectors are used to communicate turnaround passages with return passage, then the recirculating circuit is completed with no gap, but the structure becomes complex and difficult to manufacture
Solution Approach 1:
The turnaround passages and return passages are merged into a single integrated porous end cap structure rather than being separate components. The porous material itself forms the continuous recirculating circuit, eliminating the need for separate tubular connectors and their associated assembly steps, thereby simplifying manufacturing while maintaining gapless lubricant flow
Solution Approach 2:
The end cap utilizes composite construction combining sintered resinous material with integrated passage structures. This composite approach allows the lubricant passages to be formed directly within the material matrix during sintering, creating a monolithic structure that combines structural support with fluid communication functions, reducing part count and assembly complexity
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
The design achieves maintenance-free lubrication with high-speed sliding and high load capacity, maintaining effective lubrication and preventing lubricant leakage, even when the slider is reduced in width, ensuring long service life and smooth operation.
Implementation Method 1
the return passages are each made up of a tubular member of porous structure adapted to be impregnated with lubricant... capable of retaining lubricant therein and getting the lubricant oozing to facilitate high-speed sliding motion with high tact
Implementation Method 2
the tubular member of porous structure adapted to be impregnated with lubricant... continuing to apply any adequate lubricant around the rolling elements
Data Source
AI summary
A linear motion guide unit permitted to operate for long service life with substantial maintenance-free for lubrication. The linear motion guide unit has heavy load capacity even with shrinking in construction. The linear motion guide unit is allowed to work with high-speed sliding operation and high tact. To this end, return passages are made inside a carriage of a slider in a geometry lying obliquely upwards of load-carrying races. The return passages are apart away from their associated load-carrying races by a distance less or equal to twice a diametral dimension of a rolling element. End caps are integrally made with spigots each of which is raised above a surface of the associated end cap facing on the carriage, thereby providing any one of forward and aft ends of the return passage. The spigots communicate with lubricant paths extending from lubricating ports made in the end caps.