Variable Thickness Steel Strip Continuous Annealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Batch annealing of steel strips with variable thickness is costly and deteriorates the strength of steel, especially for high-strength types, due to its slow heating and cooling rates and inability to provide uniform mechanical properties across sections.
Innovation Solution
Continuous annealing of steel strips with variable thickness, allowing different temperature and heating rates for thicker and thinner sections, which enhances mechanical properties and reduces the need for high alloying elements, thereby producing tailor rolled blanks with improved strength and cost-efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If batch annealing is used for steel strips with variable thickness, then uniform temperature can be provided to both thicker and thinner sections, but the process is expensive and deteriorates the strength of steel due to slow heating and cooling rates
Solution Approach 1:
The patent applies local quality by providing different heating rates and temperatures to different sections of the strip. Thinner sections receive higher heating rates and temperatures while thicker sections receive lower heating rates and temperatures, optimizing the mechanical properties of each section individually rather than treating the entire strip uniformly
Solution Approach 2:
The patent implements dynamics by using a continuous annealing process with variable heating rates that can be dynamically adjusted along the length of the strip. The heating rate varies continuously to account for thickness variations, allowing the process to adapt to local conditions rather than maintaining a static uniform temperature profile
2Ease of manufacture
If batch annealing is used for steel strips with variable thickness, then both thicker and thinner sections can be annealed, but the process is more expensive than continuous annealing
Solution Approach 1:
The patent employs continuous annealing where the strip passes continuously through the annealing furnace, eliminating the batch-by-batch processing of traditional methods. This continuous operation improves productivity and reduces manufacturing costs while maintaining the capability to handle variable thickness strips through controlled variable heating rates
3Productivity
If continuous annealing is used for steel strips with variable thickness, then faster processing and better mechanical properties are achieved, but different temperatures must be provided to thicker and thinner sections
Solution Approach 1:
The patent addresses temperature control complexity by implementing local quality control - different heating rates and temperature profiles are applied to different sections of the strip based on their thickness. This allows faster processing while maintaining appropriate temperature conditions for each local section, transforming the complexity into a controlled advantage
4Shape
If cold rolling is used to form thicker and thinner sections, then the desired thickness variation is achieved, but the steel hardens and cannot be used directly requiring annealing
Solution Approach 1:
The patent applies parameter changes by systematically varying the heating rate and temperature parameters during annealing based on the thickness profile. Thinner sections that experienced greater cold rolling reduction receive higher heating rates and temperatures to restore ductility, while thicker sections receive milder treatment, thereby recovering the steel's workability while preserving the desired thickness variation
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
Continuous annealing results in tailor rolled blanks with higher mechanical strength and reduced alloying element requirements, achieving better mechanical properties and cost-effectiveness compared to batch annealing, with yield strengths closer between thicker and thinner sections.
Implementation Method 1
Annealing of a steel strip without thickness variations can be performed either by batch annealing or by continuous annealing. Annealing of steel strip having a variable thickness in its length direction, however, is performed only by batch annealing
Implementation Method 2
The steel strip has to be annealed to release the stresses in the strip and/or to recrystallise the strip
Implementation Method 3
the strip having been cold rolled to form the thicker and thinner sections
Implementation Method 4
During the rolling of the strip of steel the thickness is considerably reduced in the thinner portions. This results in a hardening of the steel
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a strip of steel having a variable thickness in its length direction with at least thicker sections and thinner sections, the strip having been cold rolled to form the thicker and thinner sections, one thicker and one thinner section having a length of at most a few meter, which strip has been annealed. According to the invention, the annealing has been performed by continuous annealing.