Rolling Element Screw Circulation Path Design
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Solution Overview
Problem
Conventional rolling element screw devices face challenges in forming an endless circulation path with large rolling elements and small lead lengths, leading to increased component sizes and potential interference between the pipe mounting hole and the loaded rolling element raceway groove, as well as processing errors causing steps that hinder smooth circulation.
Innovation Solution
A rolling element screw device design featuring a nut member with perpendicular circulation component mounting holes and first circulating portions with inclined rolling element introducing holes, allowing for a smaller pipe mounting hole diameter and reducing the likelihood of interference and processing errors, enabling smooth circulation even with large rolling elements and small lead lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ball introducing hole is inclined along the lead angle of the loaded rolling element raceway groove, then the rolling elements can be properly introduced into the raceway groove, but the first circulating portion increases in size
Solution Approach 1:
The ball introducing hole is formed to extend in a tangent direction along the lead angle of the loaded rolling element raceway groove, utilizing the tangential dimension to guide balls smoothly into the raceway groove without requiring a larger circulating portion size
Solution Approach 2:
The first circulating portion is configured with a specific local structure where the ball introducing hole is positioned and oriented to match the lead angle of the raceway groove, creating a localized solution that does not increase the overall size of the circulating portion
2Ease of manufacture
If the pipe mounting hole diameter is increased to accommodate the first circulating portions, then the circulation component can be mounted, but the pipe mounting hole may interfere with the adjacent loaded rolling element raceway groove
Solution Approach 1:
The pipe mounting holes are formed in a direction perpendicular to the center axis of the nut member, utilizing the radial dimension to mount the circulation component without interfering with the axial raceway groove geometry
Solution Approach 2:
The first circulating portions are configured with asymmetric positioning relative to the pipe mounting holes, allowing optimal fit and mounting while maintaining clearance from the raceway groove
3Reliability
If the first circulating portions and second circulating portion are joined together, then the circulation path is completed, but processing errors may cause steps that hinder smooth circulation of balls
Solution Approach 1:
The joint between the first circulating portions and second circulating portion is designed to create an equipotential surface for ball circulation, ensuring that balls experience no abrupt changes in elevation or resistance at the joint interface
Solution Approach 2:
The first circulating portions and second circulating portion are joined with precision matching of their mating surfaces, merging them into a continuous, smooth circulation path that eliminates steps and facilitates smooth ball flow
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
The design allows for the formation of an endless circulation path without interference and ensures smooth rolling element circulation by maintaining a small pipe mounting hole diameter and minimizing processing errors at the joint between circulating portions, enhancing the device's operational efficiency.
Implementation Method 1
a screw shaft, which has an outer peripheral surface in which a rolling element raceway groove having a spiral shape is formed at a predetermined lead angle; a nut member, which includes a through-hole through which the screw shaft passes, the through-hole having an inner peripheral surface in which a loaded rolling element raceway groove having a spiral shape and opposed to the rolling element raceway groove is formed, the nut member being threadingly engaged with the screw shaft through intermediation of a large number of rolling elements that roll on the rolling element raceway groove and the loaded rolling element raceway groove
Data Source
AI summary
The rolling element screw device includes: a screw shaft having a rolling element raceway groove; a nut member, which has a loaded rolling element raceway groove opposed to the rolling element raceway groove and is threadingly engaged with the screw shaft through intermediation of the rolling elements; and the circulation component, which includes a pair of the first circulating portions passing through a peripheral wall of the nut member, and the second circulating portion coupling the pair of first circulating portions together, to thereby form the endless circulation path for the rolling elements. Each of the first circulating portions includes a first cylindrical portion fitted into a circulation component mounting hole of the nut member, and a second cylindrical portion which has an outer diameter larger than an outer diameter of the first cylindrical portion. The first cylindrical portion includes a rolling element introducing hole.