Ball Screw Tunnel Raceway Design for Cycling Stability
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Solution Overview
Problem
Existing ball screw designs face issues with durability and cycling stability due to thin tooth thickness leading to ball impact and spatial arrangement problems, and processing difficulties in stepped designs.
Innovation Solution
A tunnel raceway type ball screw assembly featuring a screw nut with an inner thread groove, a screw shaft with outer grooves and a reflow component forming a spiral channel for ball cycling, eliminating the need for pitch shifting and preventing ball collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cycling channel extends over one single thread lead, then the structure is simple, but ball impact occurs due to thin tooth thickness
Solution Approach 1:
The cycling channel is divided into multiple segments spanning multiple thread leads rather than extending over a single lead. This segmentation allows for adequate tooth thickness in each segment while maintaining the continuous ball circulation path, thereby preventing ball impact without significantly increasing overall structural complexity.
2Reliability
If pitch shifting design is adopted, then ball impact is prevented, but spatial arrangement problems occur
Solution Approach 1:
Instead of pitch shifting in the axial dimension, the invention uses multiple thread leads in the circumferential dimension to achieve ball impact prevention. This dimensional approach allows adequate tooth thickness and proper ball circulation without the spatial arrangement problems associated with pitch shifting designs.
3Reliability
If stepped design is used to guide balls, then ball circulation is improved, but processing difficulties increase
Solution Approach 1:
The invention uses smooth curved transitions and rounded ball guide surfaces instead of stepped geometric features. This curved design provides effective ball circulation guidance while being significantly easier to manufacture using conventional machining processes, avoiding the processing difficulties associated with stepped designs.
4Volume of moving object
If outer diameter of screw nut is reduced, then compactness is improved, but ball cycling space is insufficient
Solution Approach 1:
The invention nests multiple functional elements within the screw nut structure, including multiple thread leads and integrated ball circulation paths that efficiently utilize the available radial and axial space. This nesting approach maintains compact screw nut dimensions while providing sufficient space for reliable ball cycling through optimized spatial arrangement.
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
Enhances structural durability, reliability, and cycling stability by creating an enclosed raceway for ball cycling, reducing the risk of ball impact and improving spatial arrangement without processing complexities.
Implementation Method 1
a plurality of balls, The balls are rotatably accommodated in the reflow channel or spiral channel
Implementation Method 2
The reflow component further comprises of a second reflow groove located in an opposing inner surface thereof. The second reflow groove faces toward the first reflow groove of the screw shaft, thereby defining with the first reflow groove of the screw shaft a reflow channel therebetween. The reflow channel is connected to the spiral channel.
Data Source
AI summary
A tunnel raceway type ball screw assembly includes a screw nut having an inner thread groove, a screw shaft inserted through the screw nut and including outer grooves, a mounting groove extending across the outer grooves and a first reflow groove in radial communication with the mounting groove, and a reflow component mounted in the mounting groove of the screw shaft and including a rolling groove connected with the outer grooves to form an outer thread that defines with the inner thread groove a spiral channel therebetween and a second reflow groove that defines with the first reflow groove a reflow channel therebetween in communication with the spiral channel. Thus, multiple balls can be cycled in the spiral channel and the reflow channel.