Ball Screw Stopper Geometry for Balanced Axial Load Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional ball screw device experiences a potential unbalanced load and moment due to its rotationally asymmetrical contact surface, which can lead to uneven load application and reduced lifespan when transmitting axial loads between the screw portion and a holding member.
Innovation Solution
The ball screw device is designed with a stopper having symmetrical side surfaces in the axial direction, allowing for balanced axial load transmission without applying a moment to the stopper, using a configuration where the side surfaces are connected through arc-shaped stepped portions and having a constant or varying thickness to ensure even contact and prevent stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stopper has a rotationally asymmetrical contact surface configuration, then the stroke end regulation function is achieved, but unbalanced load and moment are applied to the stopper when transmitting axial loads
Solution Approach 1:
The patent applies asymmetry in reverse by creating symmetry where previously there was asymmetry. The stopper's side surfaces are modified to be symmetrical about the axial centerline, with both surfaces having identical inclination angles relative to the axial direction. This symmetrical configuration ensures that when axial loads are transmitted through the stopper, the forces are evenly distributed on both sides, eliminating the unbalanced moment that occurred with the conventional asymmetrical design.
2Strength
If the stopper side surfaces are made symmetrical, then balanced axial load transmission is achieved, but the stroke end regulation function may be compromised
Solution Approach 1:
The patent applies local quality by differentiating the functional characteristics of different regions of the stopper. The side surfaces are designed with specific symmetrical inclination angles optimized for load distribution, while the end surface maintains a configuration optimized for stroke end regulation. This allows each surface to be locally optimized for its specific function without compromising the other, achieving both balanced load transmission and reliable stroke end regulation.
3Device complexity
If the stopper is used for both stroke end regulation and axial load transmission, then device complexity is reduced, but stress concentration occurs on the stopper
Solution Approach 1:
The patent applies universality by designing the stopper to perform multiple functions simultaneously. The symmetrical side surfaces are configured to handle axial load transmission while the end surface maintains stroke end regulation capability. This multi-functional design eliminates the need for separate components for each function, reducing device complexity while the symmetrical geometry ensures stress is evenly distributed throughout the stopper structure.
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameters of the stopper, specifically the inclination angles of the side surfaces. By setting the side surfaces at symmetrical inclination angles relative to the axial direction, the stress distribution parameters are optimized to prevent stress concentration. This parameter optimization allows the stopper to withstand both stroke end regulation forces and axial load transmission without failure.
Data Source
AI summary
A ball screw device comprising: a screw shaft, a nut, balls arranged between the shaft-side ball thread groove and the nut-side ball thread groove, a stopper including: a boss portion fitted to the fitting shaft portion of the screw shaft, and a second engaging portion protruding in the radial direction from the boss portion and engageable with a first engaging portion of the nut in the circumferential direction, and a holding member arranged adjacent to one side in the axial direction of the stopper, such that an axial load can be transmitted between the screw portion of the screw shaft and the holding member through the stopper without applying a moment to the stopper.