Steering Rack Dummy Tooth Plastic Working
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Solution Overview
Problem
The manufacturing of steering racks for automobiles is challenged by high costs and difficulty in securing strength and rigidity, particularly in forming rack teeth, which affects form accuracy and dimensional precision.
Innovation Solution
A steering rack design featuring rack teeth inclined perpendicular to the axial direction and dummy teeth formed in conjunction with the rack teeth through plastic working, such as forging, to enhance form accuracy and reduce manufacturing costs by controlling metal flow resistance during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rack teeth are formed by cutting of metal material, then manufacturing precision can be improved, but manufacturing costs increase and strength and rigidity of rack teeth deteriorate
Solution Approach 1:
The invention uses a dummy tooth as a copy or model to guide the plastic deformation process. The dummy tooth provides a template for forming the actual rack teeth through plastic working, ensuring accurate tooth geometry is replicated without requiring expensive cutting tools or fixtures.
Solution Approach 2:
The invention changes the manufacturing approach from cutting (subtractive) to plastic deformation (formative). This parameter change in the manufacturing process enables cost reduction while maintaining or improving tooth strength, as plastic deformation creates a denser metal structure compared to cutting.
2Manufacturing precision
If rack teeth are formed by cutting of metal material, then manufacturing precision can be improved, but strength and rigidity of rack teeth deteriorate
Solution Approach 1:
The invention changes the manufacturing approach from cutting (subtractive) to plastic deformation (formative). This parameter change in the manufacturing process enables cost reduction while maintaining or improving tooth strength, as plastic deformation creates a denser metal structure compared to cutting.
Solution Approach 2:
The dummy tooth serves as a physical template that ensures accurate replication of tooth geometry during plastic deformation. This copying mechanism guarantees form accuracy is achieved through the forming process itself, eliminating the need for subsequent precision cutting operations.
3Device complexity
If dummy tooth is formed uniformly, then manufacturing process is simplified, but form accuracy of rack teeth deteriorates due to uneven metal flow resistance
Solution Approach 1:
The invention introduces asymmetry in the dummy tooth design, specifically making it inclined relative to the rack teeth. This asymmetric configuration compensates for uneven metal flow resistance during plastic deformation, ensuring uniform material distribution and accurate tooth formation despite the complexity introduced by the inclined dummy tooth.
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 effectively secures form accuracy and strength of rack teeth while reducing manufacturing costs by optimizing the formation process, ensuring proper meshing with the pinion and maintaining structural integrity.
Implementation Method 1
when the plurality of rack teeth are formed by plastically deforming the material, the time consumed in processing the rack teeth can be decreased to reduce manufacturing costs, and further, it is easy to secure strength and rigidity for the rack teeth because a metal structure of the obtained rack teeth becomes precise
Data Source
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AI summary
A steering rack includes a rack shaft (10), a plurality of rack teeth (11a) formed on the rack shaft and each having a tooth trace inclined with respect to a first direction perpendicular to an axial direction of the rack shaft, and a dummy tooth (33a) aligned with the rack teeth and formed on the rack shaft. The dummy tooth (33a) is non-uniformly formed in a second direction parallel to the tooth trace of the rack tooth (11a).