Steering Rack Threaded Segment Assembly for Faster Precision Machining
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Solution Overview
Problem
The production of steering gear racks is complex due to the need for precise machining of threaded portions, requiring time-intensive and costly processes for each individual shaft segment, which complicates the manufacturing process.
Innovation Solution
A method where a continuous thread is machined on a longer shaft raw material piece, allowing for the production of threaded semi-finished products that can be cut to length, and then joined with toothed segments using friction welding, optimizing the production process by reducing re-clamping and aligning requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual shaft segments are machined separately with threaded portions, then precise machining of threads can be achieved, but production time and costs increase due to repeated re-clamping and tooling for each segment
Solution Approach 1:
The patent combines multiple shaft segments into a single continuous shaft structure, allowing the thread to be machined continuously across the entire length without re-clamping. This merging approach maintains thread precision while eliminating the productivity loss from repeated setup operations.
Solution Approach 2:
The patent performs preliminary alignment and fixation of multiple shaft segments before thread machining, creating a pre-assembled continuous shaft structure. This preliminary action ensures that the thread can be machined continuously across segment boundaries without requiring re-clamping during the actual threading operation.
2Adaptability or versatility
If multiple shaft segments are assembled separately, then flexibility in material selection and heat treatment can be achieved, but device complexity increases due to alignment and connection requirements
Solution Approach 1:
The patent divides the shaft into multiple segments that can be manufactured separately with different materials and heat treatments, then connects them through friction welding. This segmentation maintains the flexibility to optimize each segment's material properties while the standardized connection process controls the overall assembly complexity.
Solution Approach 2:
The patent replaces traditional mechanical connection methods (such as keyways, keys, or interference fits) with friction welding, which creates a more reliable and simpler connection. The friction welding process eliminates the need for complex alignment features and mechanical fasteners, reducing assembly complexity while maintaining segment flexibility.
3Ease of manufacture
If traditional individual segment processing is used, then each segment can be optimized for its specific function, but loss of time occurs due to repeated re-clamping and tooling changes
Solution Approach 1:
The patent enables continuous thread machining across the entire shaft length by pre-assembling segments with accurate alignment fixtures. This continuity eliminates the interruptions caused by re-clamping and tooling changes, maintaining the process optimization benefits while dramatically reducing production cycle time.
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 approach simplifies the production of steering gear racks by enabling efficient continuous machining of threads across the entire length of the shaft raw material, reducing production time and costs, and ensuring high precision and reliability of the ball screw drive components.
Implementation Method 1
heating the shaft raw material in a continuous hardening installation to an austenite temperature and subsequent rapid cooling
Implementation Method 2
the threaded segment and the toothed segment, by way of their joining faces, are connected to one another by friction welding in a joint
Data Source
AI summary
A rack may include a toothed portion having a toothing, and a shaft portion having a threaded portion with a coaxial thread that has a thread length in an axial direction of a longitudinal axis. Separate segments comprising at least one in each case bar-shaped toothed segment and one shaft segment are provided, are aligned on the longitudinal axis, and are connected to one another at a joint. A method for producing the rack may involve providing a shaft raw material piece having a piece length that is a multiple of a shaft segment length, generating a thread that is continuous in a longitudinal direction on the shaft raw material piece across a multiple of the thread length to produce a threaded semi-finished product, cutting to length a threaded segment from the threaded semi-finished product, providing a toothed segment, and joining the threaded segment to the toothed segment.