Ball Screw Recirculating Part Asymmetric Division
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Solution Overview
Problem
Conventional ball screw devices with small lead angles and a small number of circulation rolls face challenges in maintaining equal division of tongue portions and legs, leading to reduced strength and potential loss of ball recirculating paths, making it difficult to fabricate functional recirculating parts.
Innovation Solution
A ball screw device design featuring a recirculating part with a pair of legs and a main body, where the legs are fitted to recirculation holes orthogonal to the nut's centerline, and the main body is divided to form an intersecting second divided face, ensuring even division and strengthening the recirculating path, allowing for smooth ball circulation even with low lead angles and few circulation rolls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the recirculating part is divided into two parts radially along the centerlines of the ball recirculating paths, then the ball recirculating path can be maintained, but the strength of the tongue portion is reduced
Solution Approach 1:
The recirculating part is divided into two divided bodies that are fitted together along the ball recirculating path. This segmentation allows the recirculating part to be assembled while maintaining the continuity of the ball recirculating path, and the division line is positioned to avoid cutting through the tongue portion, thus preserving its strength.
2Strength
If the recirculating part is not divided, then the tongue portion strength is maintained, but unequal division becomes inevitable when applied to ball screw devices with small lead angles and small number of circulation rolls
Solution Approach 1:
The invention positions the division line of the recirculating part asymmetrically relative to the legs, specifically arranging it along the ball recirculating path rather than radially along the leg centerlines. This asymmetric division allows the legs to be divided equally while maintaining tongue portion strength and ensuring proper ball circulation even in devices with small lead angles and few circulation rolls.
3Ease of manufacture
If the division line is positioned radially along leg centerlines, then manufacturing is simplified, but the ball recirculating path is lost in devices with small lead angles
Solution Approach 1:
Instead of dividing the recirculating part along the radial direction (leg centerlines), the invention positions the division line along the axial direction following the ball recirculating path. This dimensional change in the division orientation allows the ball recirculating path to be maintained while still enabling manufacturing through fitted assembly of divided bodies.
Data Source
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AI summary
There is provided a ball screw device even with a small lead angle and a small number of circulation rolls, including a rotational part, which keeps unequal division of tongue portions and legs connected to the tongue portions to a minimum and ensures the strength of the tongue portions. A recirculating part 40 of the ball screw device thus includes a pair of legs 41, each having a tongue portion 44 for scooping up balls in a direction approximately tangential to a spiral raceway, and a main body 42 connecting the pair of legs 41. First divided faces A and C for dividing the pair of legs 41 along a ball recirculating path R, and a second divided face B for dividing the main body 42 along the ball recirculating path R are also included. The second divided face B is formed by an upper divided face B1 and a lower divided face B2 of the ball recirculating path R so that the upper divided face B1 and the lower divided face B2 intersect with each other when viewed from a flat surface 20a of the nut 20.