Spindle Nut Imbalance Compensation via Planar Recesses
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Solution Overview
Problem
Ball screw drives suffer from dynamic imbalance due to non-symmetric spindle nut construction, leading to increased stress, wear, and undesirable vibrations, which are costly and difficult to balance effectively without compromising stability or production costs.
Innovation Solution
Designing the spindle nut with planar recesses that are flush or countersunk to accommodate ball deflection units, allowing for self-locking and imbalance compensation through a round sleeve, and strategically placing these recesses to minimize material removal and avoid through holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spindle nut is designed with ball recirculation mechanism, then the ball screw drive achieves reverse-free positioning capability, but the spindle nut becomes dynamically unbalanced during rotation
Solution Approach 1:
The patent applies counterbalancing by drilling balancing holes through the spindle nut body at specific positions and depths. These holes remove material to create counterweights that offset the imbalance caused by the ball recirculation mechanism, thereby reducing vibrations and bearing stresses while maintaining the reverse-free positioning capability
2Object-generated harmful factors
If balancing holes are drilled deep into the spindle nut, then dynamic imbalance is reduced, but structural stability and leak resistance deteriorate
Solution Approach 1:
The patent optimizes the parameters of the balancing holes, specifically controlling their depth to be between 0.5mm and 5mm (preferably 1mm to 3mm) and positioning them at specific radial distances from the center axis. This parameter optimization achieves effective imbalance compensation while maintaining structural integrity and preventing leaks
3Object-generated harmful factors
If multiple balancing holes are drilled, then dynamic imbalance is better compensated, but manufacturing complexity and production time increase
Solution Approach 1:
The patent employs a balanced approach by drilling a limited number of balancing holes (typically 2-4 holes) rather than excessive holes. The holes are strategically positioned and sized to achieve sufficient imbalance compensation without over-complicating the manufacturing process, thus maintaining productivity while effectively reducing dynamic imbalance
Data Source
Figure 1~2
Figure 3~4
AI summary
A ball screw drive comprises at least one threaded spindle and a spindle nut, which has a substantially cylindrical outer contour with recesses for the countersunk installation of the ball deflection and deflection channel. To compensate for the imbalance that occurs during rapid rotation of the nut, at least one flat recess is provided on the outer circumference of the spindle nut. This recess is in the form of a rectangle with rounded corners, a shallow elongated hole, or a groove. The smallest dimension of this recess is greater than its depth.