Ball Screw Nut Groove Alignment via Reference Marking
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Solution Overview
Problem
Existing methods for producing ball screws fail to accurately align and form ball recirculation grooves and rolling grooves on the nut's inner surface, leading to deviations in axial, circumferential, and radial directions, which cause step differences, reduced durability, and operational issues.
Innovation Solution
A method involving a blank forming step, followed by a recirculation groove forming step using plastic working, and a rolling groove forming step, where working references are established to ensure precise alignment and formation of both grooves, using a die with a cam mechanism and holding members to maintain accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a recirculation groove is directly formed in the inner circumferential surface of the nut by plastic working, then the trouble and cost of assembly can be reduced, but the alignment precision between the recirculation groove and rolling groove deteriorates due to deformation
Solution Approach 1:
The patent applies preliminary action by forming reference marks on the nut blank before plastic working, and using these marks to guide the subsequent groove formation process. This ensures that even though deformation occurs during plastic working, the recirculation groove can be accurately positioned relative to the rolling groove by referencing the pre-established marks that account for expected deformation patterns.
Solution Approach 2:
The patent replaces traditional mechanical alignment methods with a marking-based guidance system. Instead of relying on complex mechanical fixtures or precise mechanical positioning during groove formation, the invention uses reference marks that provide a visual and physical guide for tool positioning, simplifying the mechanical system while maintaining precision.
2Device complexity
If working references are not established before groove formation, then the manufacturing process can be simplified, but deviations in axial, circumferential, and radial directions occur leading to step differences
Solution Approach 1:
The patent establishes reference marks on the nut blank before any groove formation operations. These marks serve as preliminary guides that remain visible throughout the manufacturing process, allowing workers to accurately position tools for forming both the recirculation groove and rolling groove without needing complex real-time measurement systems or complicated fixtures.
Solution Approach 2:
The reference marks act as intermediaries between the manufacturing process and the final groove geometry. Rather than directly measuring and adjusting groove positions during formation, the marks serve as intermediate reference points that translate complex alignment requirements into simple visual and physical guides for tool positioning.
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 method prevents deviations in the formation of ball recirculation and rolling grooves, ensuring accurate alignment and reducing operational issues such as step differences, enhancing durability and efficiency of ball screw movement.
Implementation Method 1
a recirculation groove forming step which forms the ball recirculation groove at the inner circumferential surface of the blank
Data Source
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AI summary
There is provided a method enabling the formation of a ball recirculation groove and a ball rolling groove at the inner circumferential surface of a nut for ball screw use in a state free of deviation in an axial direction, circumferential direction, and radial direction of the nut. An end face (111a) of a flange (111) is formed with a concave part (102), then a blank (101) is attached to a chuck (130) and an inner circumferential surface (101a) of the same and an end face (111a) and outer circumferential surface (111b) of the flange (111) are continuously ground. Due to this, the coaxiality of the inner circumferential surface (101a) of the blank (101) and the outer circumferential surface (111b) of the flange (111) and the perpendicularity of the end face (111a) of the flange (111) to the inner circumferential surface (101a) of the blank (101) are made smaller. This blank (101) is plastically worked at its inner circumferential surface (101a) to form the ball recirculation groove and is cut to form the ball rolling groove while using the concave part (102) as a phase reference, the end face (111a) as an axial direction reference, and the outer circumferential surface (111b) as a radial direction reference.