Ball Screw Nut with Integrated Circulation Grooves
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Solution Overview
Problem
Conventional ball screw devices with large leads face challenges in downsizing, weight-saving, and high production costs due to the end cap method, which requires multiple components and complex assembly, making it difficult to achieve reliability and compact design, especially in rotary applications.
Innovation Solution
A ball screw device with a novel ball circulation structure featuring a no-load ball groove and direction change grooves formed directly in the nut member's inner peripheral surface, creating a closed loop circulation path that eliminates the need for additional components and allows for compact design and low-cost manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end cap method is used for ball circulation in large lead screw shafts, then the ball circulation path can be formed, but the nut member outer diameter becomes excessively larger and the structure becomes complex
Solution Approach 1:
The invention merges the ball circulation path directly into the nut member body by forming the no-load ball groove and direction change grooves as integral parts of the nut member. This eliminates the need for separate end caps and external circulation components, thereby reducing the nut member outer diameter while maintaining reliable ball circulation functionality.
Solution Approach 2:
The invention utilizes the axial dimension of the nut member by forming the no-load ball groove extending axially and using direction change grooves at the axial ends to redirect balls. This three-dimensional groove configuration enables compact ball circulation within the nut member volume without requiring excessive outer diameter.
2Reliability
If the end cap method is used for ball circulation, then the circulation path is established, but the number of components and assembly complexity increases
Solution Approach 1:
The invention combines multiple functions (ball circulation path, direction change, and structural support) into a single integrated nut member component. The no-load ball groove and direction change grooves are formed directly in the nut member, eliminating the need for separate end caps, return tubes, or deflector components, thereby reducing component count and assembly complexity.
Solution Approach 2:
The nut member is designed to perform multiple functions simultaneously: it provides the load bearing surface, forms the ball circulation path, incorporates direction change mechanisms, and supports the screw shaft. This multi-functional design eliminates the need for dedicated separate components for each function.
3Reliability
If the end cap method is used, then ball circulation is achieved, but manufacturing cost and assembly time increase
Solution Approach 1:
The invention integrates the ball circulation path formation into the nut member manufacturing process itself. By forming the no-load ball groove and direction change grooves as integral features during nut member production (via machining or molding), the need for separate manufacturing and assembly of end caps and circulation components is eliminated, reducing both production cost and assembly time.
4Adaptability or versatility
If a gear is integrated at the nut member end portion, then rotary motion can be input, but the nut member size and weight increase with conventional methods
Solution Approach 1:
The invention merges the gear integration with the compacted nut member design. Since the ball circulation path is integrated into the nut member body without requiring end caps or external components, the gear can be directly mounted or integrated at the nut member end portion without increasing overall size or weight. The compact structure provides space efficiency for adding rotary input functionality.
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 solution enables a compact, lightweight, and cost-effective ball screw device suitable for large lead applications, with improved reliability and ease of manufacturing, allowing for integration of a gear at the nut member's end portion without increasing size or weight, and facilitating conversion to rotary ball screw devices.
Implementation Method 1
a nut member and a screw shaft are rotatably engaged with each other through an intermediation of a large number of balls arranged therebetween
Data Source
AI summary
A ball screw device having a novel ball circulation structure suitable for a screw shaft with a large lead, optimum for downsizing and weight saving of a nut member, capable of being manufactured at low cost, and capable of exhibiting high reliability even under severe use conditions. In a ball screw device where a screw shaft and a nut member are screwed to each other through an intermediation of a large number of balls, a no-load ball path which forms an infinite circulation path for the balls is constituted by a no-load ball groove spirally formed in an inner peripheral surface of a through-hole of the nut member and by a pair of direction change grooves which communicatively couple a load rolling groove and the no-load ball groove to each other so as to complete the infinite circulation path as a closed loop.