Tubular Anti-Roll Bar Grain Structure for Higher Service Life
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Solution Overview
Problem
Conventional tubular anti-roll bars have limited service life and stiffness due to internal stresses during forming, restricting their geometrical dimensions and formability, which affects their strength and durability.
Innovation Solution
A tubular anti-roll bar with a metal tubular body featuring a torsion spring portion, two bent limbs, and a bending portion with a specific grain size distribution, where the average grain size in the bending portion is 70% to 99% of that in the torsion spring portion, made from manganese-boron-steel composite, and tempered to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the diameter-wall thickness ratio is increased to reduce weight, then weight is reduced, but internal stresses increase during forming and operation, limiting the ratio to a narrow range
Solution Approach 1:
The patent applies heat treatment parameters (tempering at specific temperatures) to change the material properties of the steel tube, enabling it to withstand higher internal stresses with thinner walls. This allows increasing the diameter-wall thickness ratio while maintaining structural integrity and reducing weight.
Solution Approach 2:
The patent uses a composite microstructure approach, creating a specific grain size distribution (70%-90% of the grain size in the torsion spring portion) through controlled forming and heat treatment. This composite structural approach enhances strength-to-weight ratio, enabling weight reduction without compromising stress resistance.
2Ease of manufacture
If conventional forming procedures are used, then manufacturing is straightforward, but the parameters strength and durability are limited due to internal stresses
Solution Approach 1:
The patent introduces preliminary heat treatment (tempering) before final forming operations. This preliminary action prepares the material by reducing internal stresses and optimizing microstructure, enabling subsequent forming to achieve both high strength and good formability without compromising durability.
Solution Approach 2:
The patent changes the thermal parameters by applying specific tempering temperatures and holding times, which fundamentally alter the material's stress-state and microstructure. This parameter change enables the steel tube to achieve both ease of manufacture through forming and high reliability in service.
3Strength
If the grain size in the bending portion is reduced to increase strength, then strength improves, but the ratio becomes outside the optimal range affecting service life
Solution Approach 1:
The patent applies local quality control by specifying that the grain size in the bending portion should be 70%-90% of the grain size in the torsion spring portion. This local optimization ensures adequate strength in the bending portion while maintaining overall component reliability and service life through balanced microstructure distribution.
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 results in a tubular anti-roll bar with improved service life and adjustable stiffness and flexural strength, enabling better performance in dynamic tests and reducing variability in service life results.
Implementation Method 1
the steel tube or the steel wire may undergo various preparatory steps, which influence the spring properties and strength properties
Implementation Method 2
the average grain size, in particular after tempering, in the bending portion
Implementation Method 3
Forming the steel tube or steel wire into springs and torsion bars may take place according to forming procedures known in the prior art
Data Source
AI summary
The present invention relates to a tubular anti-roll bar for a vehicle chassis, produced from a metal tubular body, comprising a torsion spring portion, two limbs bent off from the torsion spring portion and a bending portion, arranged between the torsion spring portion and the respective bent limb and having an inside bending radius (IB) and an outside bending radius (OB), wherein the tubular anti-roll bar has a structure with grains with a grain size distribution and an average grain size, wherein the structure has a ratio between the average grain size in the bending portion of the inside bending radius (IB) in relation to the average grain size in the torsion spring portion in the range of 73% to 77%.