Ball Screw Nut Outer Geometry Freedom via Inner Circulating Passage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ball screws face challenges in designing the outer circumferential surface of the nut due to restrictions imposed by the ball circulating passage systems, limiting the geometry and freedom to attach additional members.
Innovation Solution
A manufacturing method for a ball screw nut that forms a concaved groove on the inner circumferential surface for the ball circulating passage, allowing for integrally formed outer circumferential features such as flanges, gears, and other structures, enabling arbitrary shape design and increased freedom in geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tube system or deflector system is used for the ball circulating passage, then the ball circulation function is achieved, but the outer circumferential surface geometry is restricted and freedom to attach additional members is limited
Solution Approach 1:
The ball circulating passage is moved from the outer circumferential surface to the inner circumferential surface of the nut. By forming the concaved groove on the inner circumferential surface, the patent relocates the ball circulation path to a different spatial dimension (inside vs. outside), thereby freeing the outer circumferential surface for arbitrary geometry design and attachment of additional members while maintaining reliable ball circulation.
2Reliability
If the ball circulating passage is formed on the outer circumferential surface, then ball circulation is enabled, but the outer diameter portion geometry freedom is restricted
Solution Approach 1:
The patent relocates the ball circulating passage from the outer circumferential surface to the inner circumferential surface by forming a concaved groove. This dimensional relocation allows the outer diameter portion to achieve arbitrary geometry without being constrained by the ball circulation path, while the inner surface modification maintains effective ball circulation.
3Reliability
If conventional ball circulating passage systems are used, then ball return function is achieved, but additional members cannot be freely attached to the outer circumferential surface
Solution Approach 1:
By forming the concaved groove on the inner circumferential surface, the patent moves the ball return path to the inside of the nut. This creates the outer circumferential surface as a free space that can accommodate various additional members (flanges, gears, encoders, etc.) without interfering with the ball return function, thereby enabling both reliable ball circulation and versatile attachment options.
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
Provided is a ball screw in which an outer circumferential formation such as a flange is formed at a portion facing a ball circulating passage out of outer circumferential surface of a nut. The ball screw (1) includes: a screw shaft (3) having on its outer circumferential surface a screw groove (3a) ; a nut (5) having on its inner circumferential surface a screw groove (5a) facing the screw groove (3a); a plurality of balls (9) rollably loaded in a spiral ball rolling passage (7) formed by the both screw grooves (3a,5a); and a ball circulating passage (11) to return the balls (9) from a start point to an end point of the ball rolling passage (7) for recirculation of the balls. The ball circulating passage (11) is a concaved groove formed by concaving a groove on a part of the cylindrical inner circumferential surface of the nut (5) by plastic working. Then, a flange (13) is integrally provided at a portion facing the ball circulating passage (11) and the screw groove (5a).