Ball Screw Nut Engagement Structure for Secure Ball Circulation
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Solution Overview
Problem
Conventional ball screw devices require high positional accuracy for forming through holes in the nut, which can lead to deformation and clogging of the circulation passage, and have insufficient fixing force for the circulation part, causing issues with ball circulation and early damage.
Innovation Solution
A ball screw device design featuring a housing concave groove on the nut with engaging recess portions and fixing portions that include engaging convex portions, allowing the circulation part to be securely attached without relying on precise positioning of through holes, enhancing the fixing force and reducing the risk of deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If through holes are formed with high positional accuracy in the nut, then the circulation part can be properly positioned, but the manufacturing complexity and cost increase
Solution Approach 1:
The circulation part itself serves as the positioning element through its engagement structure. The engaging convex portions on the circulation part directly engage with the engaging recess portions formed on the nut's outer circumferential surface, eliminating the need for separate positioning features like precisely formed through holes. This self-positioning mechanism reduces manufacturing complexity while maintaining proper positioning.
Solution Approach 2:
Instead of forming precise through holes in the nut to position the circulation part, the invention inverts the approach by forming engaging recess portions on the nut and having the circulation part provide the engaging convex portions. This reverses which component carries the positioning feature, simplifying nut manufacturing while achieving the same positioning function.
2Device complexity
If only through holes are used for fixing the circulation part, then the structure is simple, but the fixing force is insufficient causing early damage
Solution Approach 1:
The fixing function is segmented into multiple engagement points. Instead of relying on a single through-hole fixation method, the invention provides multiple engaging convex portions that engage with corresponding recess portions at different locations on the nut. This distributes the fixing force across multiple points, significantly enhancing overall fixing strength and reliability while maintaining structural simplicity.
Solution Approach 2:
The engaging convex portions are formed with curved surfaces that match the curvature of the nut's outer circumferential surface. This curved engagement geometry provides larger contact area and better force distribution compared to flat or sharp-edged engagement features, enhancing the fixing force while preventing stress concentration that could lead to early damage.
3Ease of manufacture
If through holes are formed at positions with deviations, then manufacturing is easier, but stress is applied to the circulation part causing deformation and clogging
Solution Approach 1:
The engagement structure is designed with built-in tolerance compensation. The engaging recess portions on the nut and corresponding convex portions on the circulation part are shaped to accommodate positional deviations without transmitting excessive stress. This beforehand cushioning design prevents deformation and clogging even when manufacturing deviations occur, eliminating the need for extremely precise hole positioning.
4Ease of operation
If the circulation part is not securely fixed, then assembly is simpler, but ball circulation is disrupted and damage occurs early
Solution Approach 1:
The circulation part's engagement structure serves dual functions: it positions the circulation part correctly and simultaneously provides secure fixation. The engaging convex portions fitting into recess portions creates both positioning and locking actions in one feature, ensuring reliable ball circulation while maintaining assembly simplicity. No separate fixation components or complex assembly steps are required.
Data Source
AI summary
A ball screw device has a screw shaft; a nut; a circulation part; and balls; a housing concave groove provided on the outer circumferential surface of the nut and linearly extending in the axial direction and opening to end surfaces on both outer sides in the axial direction of the nut, a circulation part arranged inside the housing concave groove, and the circulation part being prevented from displacing toward the outer side in the radial direction and displacing in the circumferential direction with respect to the nut by engaging an engaging convex portion of a fixing portion provided in the end portion on each of both outer sides in the axial direction of the circulation part with an engaging recess portion provided in the end portion of each of both outer sides in the axial direction of the housing concave groove.