Linear Motion Guide Race Geometry to Prevent Ball Clogging
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Solution Overview
Problem
Linear motion guide units experience clogging of rolling elements due to improper movement when installed sideways, leading to competition and loss of spacing between elements, resulting in improper movement of the slider.
Innovation Solution
Incorporating a load-carrying race with a varying contact angle, specifically increasing the contact angle at the boundary with the second circulation passage to create a speed difference between rolling elements, and using a spacer with a resin molded member to facilitate maintainability and production rationality, ensuring proper spacing and smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the linear motion guide unit is installed sideways, then it can be used in various installation configurations, but the rolling elements may clog due to improper movement
Solution Approach 1:
The load-carrying race first portion is designed with a different contact angle (greater than 45 degrees) compared to other portions (40-45 degrees). This local variation in geometric parameters creates a speed difference for rolling elements entering the load-carrying race, preventing clogging while maintaining versatility in installation configurations
Solution Approach 2:
The contact angle parameter is changed in the load-carrying race first portion to be greater than 45 degrees, while other portions maintain 40-45 degrees. This parameter change creates differential rolling speeds that prevent rolling element clogging regardless of installation orientation
2Reliability
If the contact angle is increased at the boundary with the second circulation passage, then the speed difference between rolling elements is created to suppress clogging, but the structural complexity increases
Solution Approach 1:
Only the load-carrying race first portion at the boundary with the second circulation passage is designed with a different contact angle. This localized structural modification creates the necessary speed difference without significantly increasing overall device complexity
Solution Approach 2:
The contact angle in the load-carrying race first portion is set to be greater than 45 degrees (excessive action), which is sufficient to create the needed speed difference and prevent clogging, without modifying the entire load-carrying race structure
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 solution effectively suppresses clogging and improper movement of rolling elements, ensuring smooth operation of the linear motion guide unit regardless of installation orientation, while maintaining design simplicity and reducing defects.
Implementation Method 1
a plurality of spheres as rolling elements that roll while contacting the first and second rolling surfaces
Implementation Method 2
a contact angle θ1 of the rolling element with the second rolling surface in the load-carrying race first portion being greater than a contact angle θ2
Data Source
AI summary
A linear motion guide unit includes a rail having first rolling surfaces extending longitudinally parallel to each other, a movable slider fitting over the rail, second rolling surfaces opposing the first rolling surfaces, respectively, rolling elements that roll while contacting the first and second rolling surfaces, a loop path through which the rolling elements circulate composed of a load-carrying race formed with the first and second rolling surfaces, a first circulation passage formed in the slider parallel to the load-carrying race, and two second circulation passages connecting the load-carrying race and the first circulation passage. The load-carrying race has a first portion at a boundary with the second circulation passage, and a contact angle of the rolling element with the second rolling surface in the first portion is greater than a contact angle of the rolling element with the second rolling surface in a remaining portion of the load-carrying race.