Ball Screw Deflector Geometry for Self-Aligning Assembly
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Solution Overview
Problem
The existing ball screw devices require labor-intensive assembly of the deflector, as the circular outer peripheral surface of the deflector needs to be precisely aligned with the recess portion on the screw shaft.
Innovation Solution
The ball screw device design features a recess portion on the screw shaft with a non-circular inner surface, allowing the deflector with an S-shaped groove surface to be easily inserted, eliminating the need for precise alignment and reducing assembly labor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the deflector and recess portion have circular shapes, then the deflector can be freely rotated and assembled, but precise alignment is required between the S-shaped groove surface and outer peripheral raceway surface, increasing assembly labor
Solution Approach 1:
The patent applies asymmetry by making the outer peripheral surface of the deflector and the inner peripheral surface of the recess portion non-circular shapes. This asymmetric design creates a unique fit orientation that eliminates the need for precise alignment during assembly, as the components can only be assembled in one correct orientation, thereby reducing assembly labor and time.
2Manufacturing precision
If the deflector is precisely positioned during assembly, then the S-shaped groove surface and outer peripheral raceway surface are continuous, but the assembly process requires more labor
Solution Approach 1:
The asymmetric non-circular shapes of the deflector and recess portion inherently provide precise positioning without requiring additional alignment operations. The unique geometric fit ensures that when the deflector is inserted into the recess portion, the S-shaped groove surface and outer peripheral raceway surface are automatically continuous, eliminating the need for labor-intensive precise positioning.
Solution Approach 2:
The asymmetric geometry design allows the deflector to self-position correctly during assembly. The non-circular outer peripheral surface of the deflector naturally fits into the corresponding non-circular recess portion only in the correct orientation, making the assembly process self-aligning and reducing the need for external positioning operations.
3Ease of operation
If the outer peripheral surface of the screw shaft is made non-circular to house the deflector, then the deflector aligns automatically, but the screw shaft structure becomes more complex
Solution Approach 1:
The patent introduces asymmetry by modifying the outer peripheral surface of the screw shaft to create a non-circular recess portion that matches the non-circular outer peripheral surface of the deflector. This asymmetric recess portion enables automatic alignment of the deflector during assembly, simplifying the assembly process despite the increased structural complexity of the screw shaft.
Data Source
AI summary
A ball screw device of the present disclosure includes: a screw shaft in which an outer peripheral raceway surface is provided on an outer peripheral surface; a nut into which the screw shaft is inserted and in which an inner peripheral raceway surface is provided on an inner peripheral surface; a plurality of balls arranged on a raceway between the outer peripheral raceway surface and the inner peripheral raceway surface; and at least one deflector provided with an S-shaped groove surface that circulates the balls. The outer peripheral surface of the screw shaft is provided with a recess portion that is recessed to an inner side in a radial direction and that houses the deflector, and an inner peripheral surface of the recess portion and an outer peripheral surface of the deflector are not circular when viewed from an outer side in the radial direction of the screw shaft.