Ball Screw Circulating Part Stress Reduction
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Solution Overview
Problem
Conventional ball screw devices face strength deterioration due to division in the radial direction of the circulating part, leading to potential damage during high-speed operations due to lack of backup from the nut in the ball circulation route.
Innovation Solution
The ball screw device is designed with a circulating part composed of two symmetrically divided bodies, where the internal diameter of the nut and the circular groove's inner surface are optimized to reduce stress concentration and prevent damage, ensuring appropriate projection and alignment to support the ball circulation route effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the circulating part is divided into two along a centerline of the ball circulation route, then the tang for scooping up the ball can be positioned to match the tangential direction of the spiral path, but the strength of the tang deteriorates due to the division
Solution Approach 1:
The circulating part is divided into two divided bodies that are coupled together, allowing the tang to be positioned optimally for ball scooping while maintaining structural integrity through the coupling mechanism at the divided surfaces
2Reliability
If the circulating part projects too much from the nut, then ball holding and protection from collision is improved, but damage occurs during high speed operation due to repeated load without nut backup
Solution Approach 1:
The invention optimizes the projection amount of the circulating part from the nut by establishing specific dimensional relationships (Rt ≥ Rb + Rball and Ra ≤ Rt - Rb - Rball), balancing ball protection needs with durability under high-speed operational loads
3Device complexity
If the circulating part is divided at a surface orthogonal to the ball circulation route, then the structure is simplified, but a divided surface projects from the nut causing potential damage
Solution Approach 1:
The divided surfaces are positioned asymmetrically relative to the ball circulation route, specifically away from the tang and at angles that prevent projection from the nut, optimizing both structural simplicity and strength
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A ball screw device for reducing damage to a circulating part even during a high speed operation is provided. To this end, the circulating part (40) includes a pair of legs (41,41) having a tang (44) to scoop up a ball (30) in a direction substantially match with a tangential direction of a spiral path, and a body (42) to connect the pair of legs (41,41), wherein a center path diameter Rb of the ball (30), an internal diameter Rn of the nut (20), and an internal diameter Rt opposite to the tang (44) satisfy a relationship of Rb ≦ Rt ≦ Rn.