Rack Bar Heat Treatment via Sequential Quenching
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Solution Overview
Problem
The existing methods for heat-treating rack bars in vehicle steering devices require multiple quenching devices and processes, leading to decreased productivity and potential twisting or warping of the rack teeth portion, which complicates manufacturing precision and efficiency.
Innovation Solution
A method involving continuous conveying and sequential application of quenching treatment to the entire circumferential surfaces of the rack teeth and ball screw portions using a single heat-treatment device, with independently determined quenching conditions for each portion to achieve required surface hardness and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple quenching devices and processes are used for different portions of the rack bar, then the required surface hardness for each portion is achieved, but the productivity decreases and the device complexity increases
Solution Approach 1:
The patent combines multiple quenching devices into a single integrated quenching device that can sequentially apply quenching treatment to different portions of the rack bar. This merging of functions maintains the ability to achieve required surface hardness for each portion while simplifying the overall device structure and improving productivity by eliminating the need for multiple separate devices and processes
Solution Approach 2:
The patent applies different quenching conditions (such as quenching medium temperature, quenching speed, and heating temperature) for different portions of the rack bar using a single device. By dynamically changing quenching parameters during the sequential treatment process, the invention achieves the required surface hardness for each portion while maintaining device simplicity and high productivity
2Manufacturing precision
If special quality controls are implemented to prevent twisting or warping, then manufacturing precision is maintained, but productivity decreases
Solution Approach 1:
The patent incorporates preliminary support measures and optimized quenching parameters into the standard manufacturing process, eliminating the need for special quality control interventions. By preventing deformation through proper process design rather than post-process inspection and correction, the invention maintains both high manufacturing precision and productivity
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 enhances manufacturing precision and productivity by ensuring surface hardness for all portions without multiple devices or processes, reducing the risk of twisting or warping and eliminating the need for special quality controls.
Implementation Method 1
a resistance quenching treatment is applied to the rack teeth portion so as to assure surface hardness for the teeth portion
Implementation Method 2
The ball screw portion is applied with an induction quenching treatment so as to assure surface hardness on an entire surface area thereof
Data Source
AI summary
A method of heat-treating a rack bar includes a step of continuously conveying a rack bar provided with a rack teeth portion and a ball screw portion by a quenching means, and a step of sequentially applying a quenching treatment to each circumferential surface of the rack teeth portion and the ball screw portion. The quenching treatment is preferably and sequentially applied to each entire circumferential surface of the rack teeth portion and the ball screw portion.