Ball Screw Return Path Twist for Stable Ball Positioning
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Solution Overview
Problem
In ball screws, the centrifugal force acting on balls in the return path of the circulating component causes instability, leading to uneven movement as the balls contact the arc portion at only one point, resulting in snaking and inefficient travel.
Innovation Solution
The circulating component's return path is designed with a contact portion that contacts the ball at two or more points, and this contact portion is twisted to accommodate changes in the centrifugal force direction, ensuring the ball's position remains stable throughout the curved path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the return path uses a simple arc portion with larger circle diameter than ball, then the ball can pass through the curved path, but the ball contacts at only one point causing position instability and snaking motion
Solution Approach 1:
The patent applies local quality by creating a contact portion with a specific cross-sectional shape (where the diameter is smaller than the ball diameter) at the critical location where the ball changes direction. This localized structural modification ensures that the ball contacts the arc portion at two or more points rather than one point, thereby stabilizing the ball's position in the cross-section while maintaining the overall curved path functionality.
2Volume of moving object
If the arc portion has a larger circle diameter than the ball, then the ball can fit through the return path, but the ball contacts at only one point leading to unstable position and snaking
Solution Approach 1:
The patent applies local quality by creating a contact portion with a specific cross-sectional shape (where the diameter is smaller than the ball diameter) at the critical location where the ball changes direction. This localized structural modification ensures that the ball contacts the arc portion at two or more points rather than one point, thereby stabilizing the ball's position in the cross-section while maintaining the overall curved path functionality.
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 design stabilizes the ball's position in the cross-section of the return path, reducing unnecessary movement and ensuring smooth travel even when the centrifugal force direction changes, thereby enhancing the ball's movement through the curved path.
Implementation Method 1
When the ball moves along the helical loaded ball rolling groove, the centrifugal force acts on the ball in the radial direction of the nut.
Data Source
AI summary
A bass screw can move balls smoothly in a return path of a circulating component. The ball screw includes: a screw shaft having a helical ball rolling groove on an outer peripheral surface thereof; a nut having a helical loaded ball rolling groove facing the ball rolling groove, on an inner peripheral surface thereof; a circulating component where at least part of a return path connecting one end and the other end of the loaded ball rolling groove of the nut is formed; and a plurality of balls that can circulate. A contact portion that contacts the ball at two or more points is formed on an outer peripheral side of the return path of the circulating component. The contact portion of the circulating component is twisted in accordance with a change in the direction of a centrifugal force that acts on the ball.