Tubular Stabilizer Bar Grain Control for Higher Flexural Strength
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Solution Overview
Problem
Conventional tubular stabilizers for vehicles have limited service life and variability in performance due to restricted geometric dimensions and forming processes, which affect strength and toughness, limiting their dynamic testing results.
Innovation Solution
A tubular stabilizer with a metal tubular body featuring a torsion spring section, bent legs, and a bending section with a specific grain size distribution and tempering ratio, made from manganese-boron steel, and tempered using electrical resistance heating to enhance rigidity and flexural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the diameter-to-wall-thickness ratio is increased to achieve weight savings, then the weight of the tubular stabilizer is reduced, but the flexural strength decreases due to higher internal stresses during forming and operation
Solution Approach 1:
The patent applies different microstructure grain sizes at different locations within the tubular stabilizer. The bending section has a finer mean grain size (0.8-1.5 mm) compared to the torsion spring section (1.0-2.0 mm), creating local property optimization. This allows the bending section to have enhanced strength and toughness where it is most needed, while maintaining overall weight efficiency through the high diameter-to-wall-thickness ratio (18-30).
Solution Approach 2:
The patent changes the microstructural parameters by controlling the mean grain size in different sections through specific forming and tempering processes. By adjusting the grain size ratio between 70-90% (bending section relative to torsion spring section), the patent optimizes the balance between strength, toughness, and formability, enabling weight reduction without sacrificing critical strength properties.
2Ease of manufacture
If conventional forming processes are used to manufacture tubular stabilizers, then manufacturing is simplified, but the service life and dynamic performance are limited due to restricted geometric dimensions and formability
Solution Approach 1:
The patent modifies the microstructural parameters through controlled grain size distribution and tempering processes. By achieving a specific grain size ratio (70-90%) between bending and torsion spring sections, and controlling the absolute grain size in the bending section to 0.8-1.5 mm, the patent significantly improves service life (up to 1.5 million cycles) while maintaining compatibility with conventional forming and tempering manufacturing processes.
3Reliability
If the mean grain size in the bending section is optimized relative to the torsion spring section, then the service life and toughness are improved, but the manufacturing process complexity increases due to required tempering control
Solution Approach 1:
The patent implements local quality optimization by creating distinct microstructural characteristics in different sections of the tubular stabilizer. The bending section is specifically engineered with a finer grain size (0.8-1.5 mm) compared to the torsion spring section (1.0-2.0 mm), achieving localized property enhancement. This local differentiation improves service life while using standard tempering processes rather than requiring entirely new manufacturing equipment.
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 extends the service life of tubular stabilizers and allows for customizable rigidity and flexural strength, improving performance in dynamic testing and reducing variability in service life results.
Implementation Method 1
the microstructure has a ratio between the mean grain size, in particular after tempering in the bending section
Implementation Method 2
tempered using electrical resistance heating
Data Source
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AI summary
The present invention relates to a tubular stabilizer bar (1) for a vehicle chassis, produced from a metal tubular body, the tubular stabilizer bar comprising: - a torsion spring portion (2); - two legs (3, 3') bent from the torsion spring portion (2); and - a bend portion (4, 4') between the torsion spring portion (2) and each bent leg (3, 3'), the bend portion having an inside bending radius (IB) and an outside bending radius (OB). The tubular stabilizer bar (1) has a microstructure having grains with a grain size distribution and with an average grain size, the microstructure having a ratio of the average grain size in the bend portion of the inside bending radius (IB) to the average grain size in the torsion spring portion (2) in the range of 70% to 99% or 70% to 90%, preferably in the range of 71% to 79%, more preferably in the range of 72% to 78%, most preferably in the range of 73% to 77%.