Ball Guide Turn-Around Geometry to Prevent Groove Edge Contact
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Solution Overview
Problem
The existing motion guide apparatus experiences high stress and potential indentation at the contact point between balls and the edge of the ball rolling groove when used at high speeds, as balls transfer from the inner peripheral side turn-around path to the track member.
Innovation Solution
The motion guide apparatus design ensures that the radius of curvature of the ball rolling groove (R) is greater than the distance from the ball center to the rolling surface of the inner peripheral side turn-around path (r), preventing balls from contacting the edge of the ball rolling groove by positioning the rolling surface inward of the groove's extension line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ball rolling groove edge is positioned at the standard location, then the structure is simple and easy to manufacture, but high stress and indentation occur at the contact portion when used at high speeds
Solution Approach 1:
The rolling surface is preliminarily positioned inward of the extension line of the ball rolling groove before ball contact occurs. This preliminary positioning prevents the ball from contacting the groove edge during high-speed operation, eliminating the harmful impact before it can cause indentation or damage.
Solution Approach 2:
The rolling surface acts as an intermediary element between the ball and the ball rolling groove. By positioning the rolling surface inward, it serves as a mediator that guides the ball onto the groove at an optimal angle, preventing direct contact between the ball and the groove edge.
2Reliability
If the rolling surface is positioned inward of the ball rolling groove extension line, then ball contact with groove edge is prevented, but the structural configuration becomes more complex
Solution Approach 1:
The rolling surface is merged with the inner peripheral-side component structure, integrating the protective function into the existing component rather than adding a separate element. This merging approach prevents groove edge contact while minimizing additional structural complexity.
Solution Approach 2:
The rolling surface is positioned at a specific local region (inward of the extension line) of the inner peripheral-side component. This localized positioning provides the necessary protection against groove edge contact only where needed, without requiring complex modifications throughout the entire 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
This configuration effectively prevents balls from contacting the edge of the ball rolling groove, reducing stress and potential indentation, ensuring smooth operation even at high speeds.
Implementation Method 1
A plurality of balls is disposed between the track member and the moving member in such a manner as to be capable of rolling motion. The motion of the movable body is guided by use of the rolling motion of the balls
Data Source
AI summary
A motion guide apparatus is provided which can prevent a ball from contacting an edge of a ball rolling groove of a track member when the ball transfers from a rolling surface of the inner peripheral side of a turn-around path (an inner peripheral-side component) to the track member. The motion guide apparatus includes: a track member (2) including a ball rolling groove (2a); and a moving member assembled to the track member (2) in such a manner as to be movable relative to the track member (2). The moving member includes: a moving member body having a loaded ball rolling groove facing the ball rolling groove (2a), and a return path substantially parallel to the loaded ball rolling groove; and a lid member having a turn-around path. In cross section of the motion guide apparatus perpendicular to a length direction of the track member (2), letting the radius of curvature of the ball rolling groove (2a) be R, and letting the distance from a ball center (O) to a rolling surface (21) of the inner peripheral side of the turn-around path (an inner peripheral-side component (9a)) be r, R>r is set.