Ball Screw Ball Guide Path Design
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Solution Overview
Problem
Existing ball screw apparatuses face issues with vibration and noise due to ball collisions and require a reduced ball diameter or increased number of parts when dealing with narrow groove intervals or multistreak screw grooves, as the ball guide path is solely formed by the circulating member and requires a circular arc spring ring for fixation.
Innovation Solution
A ball screw apparatus with a nut having a recess portion and a ball circulating member that includes a scoop-up portion and a guide path, where the ball guide path is formed between the nut and the circulating member, allowing the ball to be scooped up in a tangential direction without reducing the ball diameter, and featuring a spring ring for axial fixation, with the circulating member and spring ring formed integrally from synthetic resin, and a resin ball retainer between balls to alleviate friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ball guide path is formed only by the ball circulating member, then the structure is simplified, but the ball diameter must be reduced to prevent interference with the ball screw groove
Solution Approach 1:
The ball guide path is divided into two parts: the ball circulating member provides the scooping function, while the nut provides the guiding function through its inner peripheral face. This segmentation allows the ball diameter to be maintained without interference, as the guiding path is formed by the combination of both components rather than relying solely on the circulating member's size
Solution Approach 2:
The nut acts as an intermediary component that forms part of the ball guide path. By utilizing the nut's inner peripheral face to define the guide path, the system avoids the need to reduce ball diameter, as the guiding function is mediated through the nut's geometry rather than being constrained by the circulating member's dimensions alone
2Reliability
If a circular arc spring ring is used to fix the ball circulating member, then the fixation is secure, but the number of parts increases
Solution Approach 1:
The ball circulating member and the spring ring are merged into a single integral component made of synthetic resin. This combining eliminates the need for separate fixation of the spring ring, reducing the number of parts while maintaining secure fixation through the integrated elastic structure that engages with the nut's recess portion
Solution Approach 2:
The integrated ball circulating member and spring ring are formed from synthetic resin material, which provides both the structural integrity needed for secure fixation and the elastic properties required for the spring ring function. This composite material approach allows a single part to fulfill multiple functions that previously required separate metal components
3Productivity
If the ball is scooped up by the tongue portion of the circulating tube, then the ball circulation is achieved, but vibration and noise occur due to ball collision
Solution Approach 1:
The ball scoop up portion is designed with a curved surface that matches the spherical shape of the ball, allowing smooth contact and scooping action. This curved geometry enables the ball to be lifted gently without sharp impacts or collisions, reducing vibration and noise while maintaining effective ball circulation
Solution Approach 2:
The design converts the potential harmful collision between ball and circulating tube into a beneficial gentle scooping action. By using a curved scoop up portion that contacts the ball tangentially, the system transforms what would be an impact event into a smooth lifting motion, eliminating noise and vibration while achieving the desired ball circulation
Data Source
AI summary
In a ball screw apparatus according to the present invention, a ball guide path 19 for guiding a ball 15 scooped up in a tangential direction of a ball center track circle to a ball return path 17 is formed between a ball guide face 182 of a ball circulating member 18 and a ball guide path forming face 20 that is provided at a nut 12. Accordingly, it is possible to provide a ball screw apparatus capable of scooping up a ball in a tangential direction of a ball center track circle to circulate without reducing a diameter of the ball even when a groove interval of a ball screw groove is narrow or when the ball screw groove is a multistreak screw groove.