Linear Motion Guide Roller Joint Staggered Protrusions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing linear motion guide units face challenges in ensuring smooth rolling of small rollers across joints between turnaround passages and return passages, particularly under high velocity and high acceleration/deceleration conditions, due to potential gaps and discrepancies in mating constructions, which can lead to stumbling or toppling of rollers.
Innovation Solution
The design features protrusions extending from the end of the turnaround passage that form complementary fit joints with a tubular member defining the return passage, with these joints being staggered and separated along the rolling direction to guide axially opposite ends of the roller, ensuring smooth passage over joints without gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complementary mating construction is used between sleeve and end cap to ensure precise alignment, then manufacturing precision is improved, but device complexity increases due to multiple raised and recessed portions
Solution Approach 1:
The complementary mating construction is segmented into multiple raised portions and recessed portions distributed around the circumference. This segmentation allows precise alignment in multiple directions simultaneously, improving manufacturing precision while distributing the complexity across multiple simple features rather than one complex feature
Solution Approach 2:
The raised and recessed portions are pre-formed during manufacturing to establish precise alignment relationships before final assembly. This preliminary action ensures accurate positioning of the sleeve relative to end caps, improving manufacturing precision while the modular nature keeps device complexity manageable
2Manufacturing precision
If high-precision assembly is used to reduce discrepancy between sleeve and end cap, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The alignment feature is divided into multiple discrete raised and recessed portions around the circumference. This segmentation creates self-aligning interfaces that guide assembly, improving manufacturing precision while reducing assembly difficulty through inherent mechanical guidance
Solution Approach 2:
The complementary raised and recessed portions create a self-aligning mechanism where the parts guide themselves into correct positioning during assembly. This self-service feature improves manufacturing precision without requiring high-precision assembly operations, as the geometry itself ensures proper alignment
3Adaptability or versatility
If sleeve is made circular to conform to ball rolling elements, then adaptability is improved, but manufacturing precision deteriorates due to difficulty in preventing sleeve turning
Solution Approach 1:
While the sleeve maintains a circular cross-section for compatibility with ball rolling elements, asymmetric features (raised and recessed portions) are added at specific angular positions. This asymmetry prevents unwanted rotation and ensures precise angular positioning, resolving the conflict between circular geometry and angular accuracy
Solution Approach 2:
The circular sleeve is segmented with discrete raised and recessed portions at specific locations. These segmented features break the rotational symmetry, preventing sleeve turning while maintaining the overall circular shape needed for ball rolling element compatibility, thus improving manufacturing precision without sacrificing adaptability
Data Source
AI summary
A linear motion guide unit is envisaged smooth transfer of a roller from a turnaround passage to a return passage and vice versa across a joint between the turnaround passage and the associated return passage. Protrusions extending stepwise from an end of the turnaround passage come into complementary fit joints with an associated end of a tubular member defining the return passage to make wall surfaces to guide axially opposite ends of the roller, in which the joints are staggered or different in their locations between wall surfaces. The return passage is defined with a fore-and-aft hole of rectangular shape in transverse section inside a tubular member that fits into a bore made in the carriage. The tubular member is joined at lengthwise opposite ends thereof together to the protrusions that are raised above end surfaces of the end caps to extend the turnaround passage into the bore. Edges of the protrusions come into complementary fit joints with the associated ends of the tubular member to provide wall surfaces to guide axially opposite ends of the roller.