Linear Motion Guide Unit Valley Design for Rolling Element Impact
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Solution Overview
Problem
Conventional linear motion guide units suffer from damage to carriage end surfaces due to collisions from rolling elements during high-speed sliding, and the manufacturing process is labor-intensive and costly due to the need for precise formation of crownings and chamfers.
Innovation Solution
A linear motion guide unit design featuring chamfered portions on the spacers and carriage end surfaces, with R chamfered portions sloped more steeply than crownings, forming a valley portion that allows rolling elements to pass above and reduce impact, and mirror-finished surfaces to minimize friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crownings and chamfers are formed precisely to guide rolling elements smoothly, then rolling element circulation is improved, but manufacturing complexity and cost increase due to labor-intensive processes
Solution Approach 1:
The patent changes the geometric parameters of the crowning and chamfering by defining specific slope ratios (e.g., 45-degree chamfers, 10-degree crownings) and dimensional relationships (e.g., chamfer length equal to 0.5 to 2 times the rolling element diameter). These standardized parameter changes simplify manufacturing while maintaining smooth rolling element circulation and reducing the need for complex precision machining processes.
2Productivity
If high-speed sliding is achieved between slider and guide rail, then productivity is improved, but damage to carriage end surfaces occurs due to rolling element collisions
Solution Approach 1:
The patent applies preliminary action by forming crownings at the ends of the raceway groove before the rolling elements reach the carriage end surfaces. These pre-formed inclined surfaces gradually decelerate the rolling elements as they approach the end of the load-carrying race, preventing high-speed collisions with the carriage end surfaces and eliminating the need for additional protective structures.
3Manufacturing precision
If dimensional tolerance is tightened for precise formation of guide portion and raceway groove, then positioning accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the approach to dimensional control by introducing standardized geometric parameters (e.g., fixed chamfer angles of 45 degrees, crowning slopes of 10 degrees, specific length ratios) that can be manufactured using conventional machining processes. This parameter standardization maintains positioning accuracy while significantly reducing manufacturing costs by eliminating the need for tight dimensional tolerances and specialized machining operations.
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
Prevents damage to carriage end surfaces by allowing rolling elements to glide over the valley portion, reduces manufacturing complexity and cost by allowing for increased dimensional tolerance and smoother rolling element circulation, and enhances durability through reduced impact forces.
Implementation Method 1
When rolling elements roll from a load-carrying race to a turnaround passage, the rolling elements move linearly at high speed in crowning regions by the action of an inertial force
Data Source
AI summary
A linear motion guide unit prevents damage to a corner portion of an end surface of a carriage resulting from high-speed rolling of the rolling elements, and eliminates the need for strict dimensional management of facing end surfaces of the carriage and a spacer. A crowning is formed at an end portion of the carriage, and an R chamfered portion is formed at a corner of an end surface of the carriage. An R chamfered portion is formed at a corner of the end surface of the spacer. The R chamfered portions define a valley portion between the facing surfaces of the carriage and the spacer. The rolling elements roll above the valley portion while striding it to thereby be prevented from colliding against the corner portion of the end surface of the carriage, whereby damage to the corner portion of the end surface of the carriage can be prevented.