Deflector Ball Screw Groove Layout for Radial Load Durability
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Solution Overview
Problem
Deflector-type ball screws face durability issues due to excessive bearing stress from radial and moment loads, limiting their effectiveness without increasing the overall form or adding multiple deflector members.
Innovation Solution
The ball screw design positions the center of the circulation grooves at a predetermined angle relative to the shaft center, allowing adjacent raceways to share loads and distribute them evenly, thereby enhancing durability against radial and moment loads without enlarging the form or adding multiple deflector members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single deflector member with multiple circling paths is used to reduce the number of parts and axial dimension, then the number of parts and axial dimension are reduced, but the area incapable of receiving radial loads and moment loads is increased, limiting durability
Solution Approach 1:
The invention changes the arrangement dimension of circulation grooves from axial direction to oblique direction relative to the shaft center. This dimensional change allows circulation grooves to be distributed more effectively in the circumferential direction, reducing the circumferential width of deflector-only support areas while maintaining compact axial dimensions.
Solution Approach 2:
The invention creates non-uniform distribution of circulation grooves by positioning their centers on an oblique line rather than symmetrically. This local quality variation optimizes load distribution across different circumferential positions, ensuring that raceways and deflector members share loads more evenly.
2Length of moving object
If circulation grooves are arranged in the axial direction of the threaded shaft, then the axial dimension is reduced, but the circumferential width of the deflector member's support area is increased, causing uneven load distribution
Solution Approach 1:
The invention transitions the circulation groove arrangement from purely axial alignment to oblique alignment relative to the shaft center. This introduces a circumferential component to the groove distribution, reducing the circumferential width of deflector-only support areas while preserving compact axial dimensions.
Solution Approach 2:
The invention changes the angular parameter of circulation groove positioning from axial (0 degrees) to oblique (20-60 degrees relative to shaft center). This parameter change optimizes the spatial distribution of grooves, achieving better load sharing between raceways and deflector members.
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
The present invention addresses the problem of providing a deflector-type ball screw capable of improving durability with respect to radial loads and moment loads without enlarging the overall shape or providing multiple deflector members. The present invention is a ball screw nut (3) in which a threaded shaft (4) is inserted in a nut (6), multiple balls (7) are disposed in rolling tracks configured from shaft-side thread grooves (4A) of the threaded shaft (4) and nut-side thread grooves (6A) of the nut (6), and the threaded shaft (4) or the nut (6) is provided with a deflector member (15) in which multiple circulation grooves that make the rolling tracks into circling paths are formed. In the ball screw nut: one circumferential direction end of at least one of the multiple circulation grooves is disposed at a position that is shifted in one circumferential direction or the other with respect to the one circumferential direction ends of the other multiple circulation grooves.