Nested Sheet-Metal Ball Screw Nut for Hardness and Weldability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ball screw threaded nuts face challenges in material selection due to conflicting requirements for weldability and hardness, leading to complex production processes.
Innovation Solution
A threaded nut design comprising an inner and outer sleeve made of sheet metal, nested axially, with a helically formed thread creating a ball groove and outer ridge, allowing for a function-specific selection of steels for each sleeve, enabling easy weldability and hardness, and a non-rotatable connection through thread engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single material is used for the threaded nut to ensure sufficient hardness for the ball groove, then weldability deteriorates
Solution Approach 1:
The threaded nut is divided into two separate sleeves: an inner sleeve that contacts the balls and requires high hardness, and an outer sleeve that provides weldability for mounting. This segmentation allows each component to be made from material optimized for its specific function, resolving the contradiction between hardness and weldability.
Solution Approach 2:
Different material properties are applied to different regions of the threaded nut. The inner sleeve is made from hardenable sheet steel (e.g., with higher carbon content) to provide sufficient hardness for ball groove contact, while the outer sleeve is made from easily weldable sheet steel (e.g., with lower carbon content) to facilitate welding to machine parts. This local differentiation of material properties resolves the contradiction.
2Ease of manufacture
If different materials are selected for weldability and hardness, then production complexity increases
Solution Approach 1:
The inner sleeve is nested within the outer sleeve to form a compact threaded nut assembly. This nesting arrangement allows two different materials to be used without significantly increasing overall complexity, as the components fit within each other's spatial envelope. The nested structure simplifies assembly and maintains a compact form factor while enabling differentiated material selection.
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 design facilitates economical production with improved material selection flexibility, ensuring effective weldability and hardness, while maintaining a stable connection between the sleeves.
Implementation Method 1
a forming tool (16) moves into the nut sleeve (3) and forms a thread (4) wound helically about a longitudinal axis, which forms a ball groove (5) wound helically about the longitudinal axis of the threaded nut on an inner circumference of the nut sleeve (3)
Implementation Method 2
The thread formed in the nut sleeve causes a positive engagement of the inner sleeve and the outer sleeve with one another with regard to an axial load on the threaded nut
Data Source
AI summary
The disclosure relates to a threaded nut of a ball screw, the threaded nut having an inner sleeve made of sheet metal and an outer sleeve made of sheet metal, which are nested axially in one another to form a nut sleeve. The nut sleeve is provided with a thread, which is formed helically about a longitudinal axis of the threaded nut and which forms, on the inner circumference of the nut sleeve, a ball groove wound helically about the longitudinal axis of the threaded nut and, and on the outer circumference of the nut sleeve, a helically wound outer ridge.