Shaft Circulation Ball Screw Stop Portion Height Optimization
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Solution Overview
Problem
Ball screws face manufacturing difficulties and reduced structural strength due to thin circulation members when the stop portion is either too high or too low, leading to potential damage and reduced life from rolling element collisions and rubbing.
Innovation Solution
A shaft circulation ball screw design with a stop portion height (H) between Hmax-0.5xBD and Hmax, where Hmax is defined by the relation Hmax = R1 + 0.5 × PCD - R1 × sin α, and a guide portion in the return passage to facilitate smooth rolling element circulation, ensuring adequate thickness and structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stop portion is positioned too high (H > Hmax), then the circulation member can be contained, but the circulation member thickness becomes too thin and may be damaged
Solution Approach 1:
The patent applies parameter changes by establishing a specific height range for the stop portion (Hmax-0.5xBD ≤ H ≤ Hmax) rather than using a fixed position. This parameter optimization ensures the circulation member has adequate thickness while being properly contained, resolving the contradiction between containment reliability and member strength.
2Device complexity
If the circulation path spans a single pitch, then the structure is simple, but manufacturing difficulties increase when low lead is close to rolling element diameter
Solution Approach 1:
The patent extends the circulation path from a single-pitch configuration to a multi-pitch configuration. This dimensional change in the circulation path layout allows the ball screw to accommodate low lead conditions without increasing device complexity significantly, while substantially improving ease of manufacture by providing adequate space for rolling element circulation.
3Device complexity
If there is no guiding structure at the return passage entrance, then the structure is simple, but rolling elements have difficulty entering the return passage
Solution Approach 1:
The patent introduces a guiding structure at the return passage entrance as an intermediary element. This guide smoothly directs rolling elements from the helical groove into the return passage, facilitating easy entry without significantly increasing overall device complexity. The guide acts as a mediator that resolves the conflict between structural simplicity and operational ease.
Data Source
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AI summary
A shaft circulation ball screw includes: a screw (10), a nut (20), a circulation member, and two fixing rings. The screw is provided with a stop portion for the two ends of the circulation member (50) to rest against, a distance from the stop portion to a central axis of the screw is defined as a first height H, a distance from a highest point of the rolling elements (40) which are located in the return passage to the central axis of the screw is defined as a second height Hmax, and Hmax satisfies the following relation: Hmax-0.5xBD≤H≤ Hmax.