Recirculating Ball Nut Hybrid Forging and Cutting Process
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Solution Overview
Problem
Existing manufacturing methods for recirculating ball nuts in ball screw drives, such as forging and milling, fail to achieve sufficient precision and material efficiency, leading to high manufacturing costs and difficulties in accessing internal ball tracks, which affects the accuracy and reliability of steering force transmission in power steering systems.
Innovation Solution
A hybrid manufacturing method combining precision forging for the base body and cutting, specifically milling, to create recirculating ball tracks with high precision, allowing for a one-piece construction without undercuts and reducing material waste, while enabling separate and precise manufacturing of the belt pulley and recirculating ball nut components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If forging methods are used to manufacture recirculating ball nuts, then material usage is efficient and production is faster, but manufacturing precision of ball tracks is insufficient
Solution Approach 1:
The manufacturing process is segmented into two distinct phases: forging for the base body and cutting for the ball tracks. This segmentation allows each process to be optimized independently - forging for speed and material efficiency, cutting for precision
Solution Approach 2:
The base body is pre-formed through forging before the precision cutting of ball tracks. This preliminary action creates a near-net-shape component that reduces subsequent material removal and machining time
2Manufacturing precision
If milling methods are used to manufacture recirculating ball nuts, then manufacturing precision is high, but material waste is very large
Solution Approach 1:
The base body is pre-formed through forging before the precision cutting of ball tracks. This preliminary action creates a near-net-shape component that reduces subsequent material removal and machining time
Solution Approach 2:
The patent changes the manufacturing parameter from complete milling to hybrid forging-cutting, transforming the process from material-removal intensive to a combination of material-forming and selective material-removal
3Ease of manufacture
If recirculating ball nut is divided into multiple segments, then internal ball tracks become accessible for manufacturing, but steps or shoulders are created that hinder smooth operation
Solution Approach 1:
The base body is pre-formed through forging with a smooth internal surface before ball track machining, eliminating the need for segmentation and subsequent joining operations that would create steps or shoulders
4Loss of substance
If precision forging is used for the base body, then material usage is optimized, but subsequent cutting process requires more material removal
Solution Approach 1:
The base body is pre-formed through precision forging with near-net-shape accuracy, minimizing the amount of material that needs to be removed in subsequent cutting operations while maintaining final precision requirements
Data Source
AI summary
A method of manufacturing a recirculating ball nut for a ball screw drive, comprising a base body which includes at least one recirculating ball track, the method comprising the following manufacturing steps: manufacturing the base body by precision forging; and finishing the recirculating ball track by a cutting method subsequent to manufacturing the base body.