Screw Device Curvature Radius Change Section
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Solution Overview
Problem
Conventional screw devices experience sudden changes in centrifugal force and positional displacement of rolling members at the boundary between the helical loaded rolling path and the linear return path, leading to potential jamming and irregular movement.
Innovation Solution
The screw device incorporates a curvature radius change section in the return path, where the curvature radius of the track centerline increases gradually or in a stepped manner, ensuring that the centrifugal force on rolling members changes smoothly as they transition between paths, preventing sudden positional changes and ensuring continuous alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the return path is designed as a linear track, then the structure is simple, but the rolling members experience sudden changes in centrifugal force and positional displacement at the boundary with the loaded rolling path
Solution Approach 1:
The return path is designed with a curved track instead of a linear one, creating a curvature radius change section that gradually transitions from the loaded rolling path. This curved configuration allows rolling members to experience gradual changes in centrifugal force and maintains continuous contact with the track wall, preventing sudden positional displacements and improving movement stability.
2Reliability
If the curvature radius of the return path is increased, then the centrifugal force on rolling members changes smoothly, but the return path length increases
Solution Approach 1:
The return path incorporates a curvature radius change section where the curvature radius varies along the path length. This dynamic variation allows the path to achieve smooth centrifugal force transitions while controlling the overall path length, as the curvature changes gradually rather than maintaining a constant large radius throughout.
3Ease of operation
If the return path has a larger inner diameter than rolling members, then rolling members can move freely, but this causes play and zigzag movement when jamming occurs
Solution Approach 1:
The curved return path with controlled inner diameter creates a balance between freedom of movement and positional stability. The curvature generates centrifugal force that presses rolling members against the track wall, eliminating play and preventing zigzag movement during jamming, while still allowing smooth circulation.
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
This configuration prevents sudden changes in centrifugal force and positional shifts, allowing for smoother movement of rolling members and reducing the likelihood of jamming by maintaining continuous alignment and applying a pressing force that keeps rolling members aligned in the return path.
Implementation Method 1
Since the rolling members move along the helical track in the loaded rolling-member rolling path, centrifugal force acts on the rolling members. In contrast, when the rolling members move along the linear track in the return path, there is no centrifugal force acting on the rolling members.
Data Source
AI summary
Provided is a screw device in which a sudden change in force on or a sudden change in the positions of the rolling members can be suppressed at the boundary between a helical loaded rolling-member rolling path and a return path of the screw device.A curvature radius change section is provided in the return path of the screw device. When viewed in the axial direction of a nut, the curvature radius change section is configured so that the curvature radius of a track centerline of the rolling members in the return path is equal to or larger than the curvature radius of a track centerline of the rolling members in the loaded rolling-member rolling path, and so that the curvature radius of the track centerline of the rolling members in the return path increases gradually or in a stepped manner with increasing distance from the loaded rolling-member rolling path.