Hollow Rack Bar Forming With Precise Angular Rack Alignment
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Solution Overview
Problem
Existing methods for manufacturing rack bars for vehicle steering apparatuses require additional steps for joining and finishing, which can complicate the process and reduce productivity, especially when aiming for a lightweight design with accurate angular positional differences between racks.
Innovation Solution
A method involving a single hollow shaft member where flat surfaces are formed on either end, allowing for precise plastic deformation using a mandrel and teeth die to create racks with an angular positional difference, improving accuracy and reducing the need for joining multiple components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple shaft members are joined to form a rack bar, then the rack bar can achieve desired structural properties and angular positional differences, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent merges multiple shaft members into a single integrated rack bar structure. The rack bar is formed as one piece with multiple hollow shaft portions connected by thick-walled portions, eliminating the need for joining operations while maintaining the angular positional difference between racks through precise forming processes.
Solution Approach 2:
The angular positional difference is predetermined during the forming process of the single rack bar. The thick-walled portions are formed at specific angles relative to each other during manufacturing, so that no additional adjustment or alignment operations are needed during assembly, thereby improving productivity while maintaining precision.
2Adaptability or versatility
If multiple shaft members are joined to form a rack bar, then structural flexibility is achieved, but additional joining steps and finishing operations are required
Solution Approach 1:
Multiple shaft members are merged into a single integrated structure. The rack bar comprises multiple hollow shaft portions that are structurally flexible and can be formed in various configurations, but they are manufactured as one piece rather than being assembled from separate components, thereby reducing device complexity.
Solution Approach 2:
Different portions of the rack bar have different structural properties tailored to their specific functions. The hollow shaft portions provide flexibility and weight reduction, while the thick-walled portions provide strength and rigidity at critical junctions. This local differentiation of material properties allows structural flexibility without requiring multiple separate components.
3Productivity
If a solid shaft member is used, then joining operations are avoided, but the rack bar weight increases
Solution Approach 1:
The rack bar uses hollow shaft portions instead of solid shaft portions to reduce weight. The hollow structure maintains sufficient structural strength while significantly reducing material usage and overall weight, achieving a balance between manufacturing simplicity and weight reduction.
4Ease of manufacture
If joining operations are performed, then modular assembly is achieved, but joining strength and finishing quality must be ensured
Solution Approach 1:
The rack bar is manufactured as a single integrated piece with multiple hollow shaft portions and thick-walled portions, eliminating all joining operations. This merging approach ensures inherent reliability and strength without the need for additional joining processes, while still allowing for modular-like functionality through the multi-section design.
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 enhances productivity by accurately forming racks with angular positional differences from a single hollow shaft member, resulting in a lightweight rack bar with improved manufacturing efficiency and accuracy compared to traditional methods.
Implementation Method 1
press-fitting a mandrel into the hollow shaft member through a first opening of the hollow shaft member on a side of the first end portion of the hollow shaft member in a state in which a teeth die corresponding to the first rack is pressed against the first flat surface to cause a material of the hollow shaft member at the first flat surface to plastically deform toward the teeth die
Data Source
AI summary
A method for manufacturing a rack bar having a first rack and a second rack is provided. The first and second racks have an angular positional difference around an axis of the rack bar. The method includes forming a first flat surface and a second flat surface on an outer circumference of a single hollow shaft member, with the angular positional difference being provided between the first and second flat surfaces, and forming the first rack on the first flat surface and the second rack on the second rack surface by press-fitting one or more mandrels into the hollow shaft member in a state in which one or more teeth dies corresponding to the first rack and the second rack is pressed against the first flat surface and the second flat surface.