Ball Screw Stopper Structure for Balanced Axial Load Transfer
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Solution Overview
Problem
The conventional ball screw device experiences a potential unbalanced load or moment load 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 rotationally symmetrical contact surfaces on both sides, allowing axial load transmission without applying a moment to the stopper, thereby ensuring balanced load distribution and preventing screw shaft inclination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stopper has a rotationally asymmetrical contact surface design, then the stroke end regulation function is achieved, but unbalanced load or moment load occurs when transmitting axial loads
Solution Approach 1:
The patent applies asymmetry in reverse - it intentionally creates a rotationally symmetrical contact surface design to eliminate the harmful asymmetry caused by the conventional asymmetrical stopper design. The symmetrical first and second contact surfaces ensure balanced load distribution when axial loads are transmitted between the screw portion and holding member, preventing moment loads and unbalanced forces that would otherwise occur with the asymmetrical conventional design.
2Device complexity
If the stopper contact surface is rotationally asymmetrical, then the structure is simpler, but the load application becomes uneven reducing device lifespan
Solution Approach 1:
The patent uses the asymmetry principle by implementing rotational symmetry - a special case of symmetry that maintains structural simplicity while eliminating the harmful effects of asymmetrical load distribution. The rotationally symmetrical contact surfaces allow the stopper to maintain its simple structure while ensuring even load application, thereby extending device lifespan without increasing complexity.
3Ease of operation
If axial load is transmitted through the stopper with asymmetrical contact surface, then the holding member is connected, but moment load is applied to the stopper
Solution Approach 1:
The patent applies symmetry to counteract the moment load problem. By designing the contact surfaces to be rotationally symmetrical rather than asymmetrical, the axial load is distributed evenly across the contact surfaces, preventing the generation of moment loads that would occur with asymmetrical surfaces. This maintains ease of axial load transmission while eliminating the harmful moment forces.
Data Source
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AI summary
A ball screw device that is capable of transmitting an axial load between the screw portion and the holding member without shortening the life of the ball screw device is provided. The stopper 5 is externally fitted to the fitting shaft portion 10 of the screw shaft 2 having an outer diameter smaller than that of the screw portion 9, which is provided adjacent to one side in the axial direction of the screw portion 9 provided with the shaft-side ball thread groove 12 on the outercircumferential surface, so as not to be able to rotate relative to each other. The driving member 6 which is a holding member is arranged adjacent to the one side in the axial direction of the stopper 5 such that the stopper 5 is held in the axial direction between the driving member 6 and the screw portion 9. An axial load is transmitted between the driving member 6 and the screw portion 9 without applying a moment to the stopper 5.