Rack Manufacturing Using Stepped Punch for Tooth Depth Control
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Solution Overview
Problem
Conventional methods for manufacturing steering gear racks face challenges in maintaining consistent tooth depth along the axial direction, leading to potential engagement issues with the pinion and increased manufacturing costs due to the need for dummy teeth and longer processing tools.
Innovation Solution
A manufacturing method and device that form rack teeth by pressing a teeth-forming punch with a stepped or inclined surface against a metal raw material, preventing metal material movement and ensuring consistent tooth depth through controlled axial pressure, eliminating the need for dummy teeth and optimizing tool length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rack teeth are formed by cutting process, then manufacturing precision can be maintained, but manufacturing cost increases and strength and rigidity of rack teeth deteriorate
Solution Approach 1:
The patent replaces the traditional cutting process with a plastic deformation process using a grooved punch. Instead of removing material through cutting, the punch presses into the rack blank to form teeth through plastic flow, substituting a mechanical cutting system with a forming system that achieves both cost reduction and improved mechanical properties.
Solution Approach 2:
The patent changes the fundamental manufacturing parameter from material removal (cutting) to material redistribution (plastic deformation). By controlling the groove geometry and pressing force, the process achieves precise tooth depth control while reducing manufacturing cost and improving tooth strength through dense metal structure.
2Ease of manufacture
If rack teeth are formed by plastic deformation, then manufacturing cost is reduced and strength and rigidity are improved, but tooth depth consistency along axial direction deteriorates
Solution Approach 1:
The patent applies local quality by designing the punch with specific groove geometry concentrated at the pressing surface. The groove shape and depth are optimized locally to control metal flow precisely where needed, ensuring consistent tooth depth across the axial direction while maintaining the benefits of plastic deformation.
Solution Approach 2:
The patent incorporates preliminary action by designing the grooved punch to pre-control the plastic deformation pattern. The groove geometry is predetermined to guide metal flow and ensure uniform tooth depth formation across the entire axial length of the rack, preventing the inconsistency problem that occurs in conventional plastic deformation methods.
3Reliability
If dummy teeth are provided to maintain engagement, then reliability of tooth engagement is improved, but device complexity and processing tool length increase
Solution Approach 1:
The patent replaces the mechanical solution of adding dummy teeth with a controlled plastic deformation process. The grooved punch design ensures proper tooth formation and engagement without requiring additional dummy teeth, thereby reducing device complexity and tool length while maintaining engagement reliability.
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 method maintains proper tooth engagement between the rack and pinion, reduces manufacturing costs by minimizing dummy teeth, and enhances the structural integrity of the rack teeth, ensuring consistent performance and assembly accuracy.
Implementation Method 1
forming rack teeth on a surface on one side in the radial direction by pressing a teeth-forming punch that is provided with rack-shaped uneven processing teeth against a surface on one side in the radial direction of part in the axial direction of a raw material made of metal, and causing the surface of the one side in the radial direction to plastically deform
Data Source
AI summary
Provided are a manufacturing method and manufacturing device that allow the depth of rack teeth to be adequately maintained across the axial direction. A stepped surface (47) is provided on one surface in the axial direction of a pressure punch (46) that moves together with a teeth-forming punch (32). The teeth-forming punch (32) is displaced downward and rack teeth are formed on the upper surface of an intermediate material (23). At the same time, the surface on the end in the axial direction of the intermediate material (23) is pressed in the axial direction by a movable die (41a) due to the engagement between the stepped surface (47) and the surface on the other side in the axial direction of the movable die (41a).