Ball Screw Nut Recirculation Insert Orientation
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Solution Overview
Problem
Existing ball screw-nut systems face challenges in recycling ball devices, particularly with complex manufacturing and assembly issues, including difficulty in attaching recirculation inserts due to small diameters and high stress forces, leading to inefficiencies and potential failures.
Innovation Solution
A ball screw-nut mechanism with recirculation inserts positioned externally on the nut, featuring a holding body and orientation lugs for precise positioning and orientation, and a transfer groove design that allows balls to circulate above the screw thread, reducing friction and stress on the inserts, while maintaining efficient stress transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If recirculation inserts are positioned inside the nut, then ball recirculation is achieved, but assembly becomes extremely difficult due to small diameter threaded holes and complex tooling requirements
Solution Approach 1:
The patent inverts the conventional approach by positioning recirculation inserts outside the nut rather than inside. The inserts are mounted on the external cylindrical surface of the nut, completely reversing the traditional internal positioning method. This inversion eliminates the need for complex internal assembly through small threaded holes while maintaining the essential function of ball recirculation.
Solution Approach 2:
The patent transitions the insert positioning from the internal radial dimension (inside the nut) to the external radial dimension (outside the nut). By moving the inserts to the external cylindrical surface of the nut, the design utilizes a different spatial dimension that is accessible during assembly without requiring complex internal tooling operations.
2Ease of operation
If recirculation inserts are positioned outside the nut, then assembly is simplified, but stress forces on inserts may increase
Solution Approach 1:
The patent introduces a holding body as an intermediary component between the nut and the recirculation inserts. This holding body is fixed to the nut's external surface and provides mounting structures (such as recesses or attachment points) for the inserts. The holding body acts as a mediator that distributes and manages the stress forces acting on the inserts, protecting them from excessive loads while maintaining the simplified external positioning arrangement.
3Reliability
If multiple recirculation inserts are used, then ball recirculation efficiency improves, but manufacturing and assembly complexity increases
Solution Approach 1:
The patent designs the external holding body and insert mounting structures as universal components that can accommodate multiple recirculation inserts in a standardized manner. The holding body incorporates multiple identical mounting positions or recesses arranged on the nut's external surface, allowing several inserts to be installed using the same manufacturing processes and assembly methods. This universal design approach enables the system to benefit from multiple inserts for improved ball recirculation without proportionally increasing manufacturing and assembly complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Simplifies machining and assembly, ensures precise and stable orientation of the transfer groove, and maintains efficiency under significant stress without notable degradation, reducing the risk of failure and manufacturing complexity.
Implementation Method 1
a transfer groove (36) modifying locally the path of the balls in order to force them to circulate above the thread of the screw (14) in order to return them upstream of the raceway (26)
Implementation Method 2
the second end of each recirculation insert (32) is provided with an orientation lug (38) having a predetermined angular position relative to the transfer groove (36)
Implementation Method 3
a holding body (40) for the recirculation inserts (32), configured for keeping said recirculation inserts (32) in said housings (30)
Implementation Method 4
by balls (28) of a calibrated diameter circulating in a raceway (26) constituted by the conjunction of the thread of the screw and that of the nut, in which the balls transmit the stress between the screw and the nut, without virtually any friction
Data Source
AI summary
A ball screw and nut mechanism has a screw in cooperation with a nut via balls that can circulate in a raceway formed by the opposing threads of the screw and nut. The nut has a recirculation insert passing therethrough from the outer face to the thread, the recirculation insert having a first end with a ball transfer groove turned towards the screw. The mechanism has a holding body for holding the recirculation insert in the housing, the recirculation insert having a second end with a shoulder bearing on the nut, the second end of the recirculation insert having an orientation lug having an angular position predetermined and fixed relative to the ball transfer groove, the orientation lug cooperating with a guide relief of the holding body to fix an orientation of the recirculation insert such that the transfer groove is adjusted to the raceway.