Modeling and exploiting the strip tension influence on surface imprinting during temper rolling of cold-rolled steel
01 Nov 2021-Vol. 3, pp 100045
TL;DR: In this paper, the influence of strip tension on the imprinting of surface roughness during temper rolling is analyzed based on a multi-scale FE modeling concept to explore new ways for surface Roughness control.
Abstract: To produce cold-rolled steel strips with specific mechanical properties and surface roughness typically temper rolling is adopted. In most cases, a uniform roughness pattern on the strip surface is mandatory. Due to the wear of the textured work rolls, their surface roughness ( R a ) continuously reduces during the process, which should be accounted for process control. However, conventional temper rolling systems fail to guarantee a uniform surface roughness. In this work, the influence of strip tension on the imprinting of surface roughness during temper rolling is analyzed based on a multi-scale FE modeling concept to explore new ways for surface roughness control. This is done in simulation where, a macroscopic rolling model incorporating strip tension is coupled to a mesoscopic imprinting model and both models are validated using copper rolling trials. The influence of different thickness reductions, strip tensions and incoming strip's surface roughness on imprinting is modeled and compared. The numerical results reveal that a higher strip tension decreases the roughness transfer, which presents potential to control the roughness transfer ratio without changing other process parameters like the prescribed thickness reduction in the future.
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01 Jan 1997
TL;DR: In this paper, the functional behavior of the surface texture according to paint appearance was investigated. And the results showed that Fourier analysis might be the best approach to predict the appearance after painting, and this independently of the texturing process.
Abstract: Paint appearance is an important factor in the overall product quality of steel sheet, especially in the automotive industry. The present paper deals with the functional behaviour of the surface texture according to paint appearance. The main results on the improvement of paint appearance of outer car body panels, obtained with coated and uncoated cold rolled steel, textured with EBT-rolls, is reviewed. There are different methods to relate steel sheet surface texture to the appearance after painting. From the literature it is found that waviness has a detrimental effect on the surface appearance after painting. Different roughness and waviness parameters are compared in order to find a good relation with paint appearance. The following surface texture parameters are evaluated in this study: roughness parameters Ra, peak count Pc, waviness parameters Wca and amplitude between 0.5 – 5mm (Fourier analysis) and envelope parameters motif W and Ra-macro, measured with a spherical stylus of radius 1.5mm. Classical parameters such as Ra and Pc are only able to evaluate paint appearance for one single texturing process, and within very limited range. The ability to predict paint appearance by Ra-macro and Wca also seems to be limited, because of their dependency on the roll texturing technique. Based on extensive testing, it is suggested that Fourier analysis might be the best approach to predict the appearance after painting, and this independently of the texturing process. The results clearly show the improved appearance of Sibetex textured sheets compared to conventional textured sheets. This is due to the fact that, with Sibetex sheet, a reduction in waviness can be achieved.
40 citations
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23 Dec 2022TL;DR: In this article , a multi-task attention convolutional long short-term memory (MACL) neural network model was proposed to predict hydrogen ion and ferrous ion concentrations simultaneously.
Abstract: Abstract The accurate measurement of acid concentration, including hydrogen chloride (HCl) and ferrous chloride concentrations (FeCl 2 ), is a critical part of ensuring the quality of strip steel pickling. In this study, a multi-task attention convolutional long short-term memory (MACL) neural network model was proposed to predict hydrogen ion and ferrous ion concentrations simultaneously. Firstly, in order to extract significant information from the input sequence, an attention mechanism was added to the model to calculate the correlation between the input features and the acid concentration at each time step. Next, multi-task learning explores the connections between the two tasks and exploits hidden constraints to improve prediction accuracy. Finally, deep features were extracted through convolutional long short-term memory (CLSTM) neural network, and the acid concentration was predicted. The proposed MACL model was compared with other popular prediction models. The experimental results show that proposed MACL model generally outperforms other models, indicating that proposed model has excellent predictive performance and effectiveness.
References
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TL;DR: In this paper, conditions for instability of plastic strain under plane stress for a material conforming to the Mises-Hencky yield condition and strain-hardening according to a unique relationship between root-mean-square values of shear stress (q) and incremental strain (δψ).
Abstract: This paper examines the conditions for instability of plastic strain under plane stress for a material conforming to the Mises-Hencky yield condition and strain-hardening according to a unique relationship between root-mean-square values of shear stress (q) and incremental strain (δψ).
If, under fixed loading conditions, the material undergoes a strain increment which is consistent with the applied stress system, the conditions are stable or unstable according as the increment in representative yield stress is greater or less than the increment in representative induced stress.
The strain at which instability arises is found in terms of the biaxial stress ratio p2/p1 under different conditions of applied loading, and the effect is demonstrated of strain-hardening according to an empirical relation of the type q = c (a + ψ)n.
The analysis is also applied to certain cases of non-uniform stress distribution. In the case of the hydrostatic bulge results are obtained showing a critical thinning ranging from 26 per cent for a non-hardening material to about 45 per cent for typical strain-hardening materials, values in general agreement with experimental data. Conditions over the punch head in the pressing of a cylindrical shell are discussed but computations are not attempted.
1,604 citations
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01 Jun 1948TL;DR: In this paper, an approximate theory for roll force and torque with and without front and back tensions applied to the strip is presented. And the accuracy of the calculations without tensions is within about 15 per cent.
Abstract: From an approximate theory, equations are derived for roll force and torque with and without front and back tensions applied to the strip. Where tensions are applied the calculations for each pass take about an hour; without tensions, and with the use of curves given in this paper, they can be carried out in ten minutes. The accuracy of the calculations without tensions is within about 15 per cent.At the end of the paper there is a discussion of the energy relationships in rolling. At present this should be considered as speculative in character.
270 citations
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TL;DR: In this paper, a theory of cold rolling of thin gauge strip is presented which, within the idealizations of homogeneous deformation and a constant coefficient of Coulomb friction, rigorously models the elastic deformation of the rolls and the frictional traction at the interface.
Abstract: A theory of cold rolling of thin gauge strip is presented which, within the idealizations of homogeneous deformation and a constant coefficient of Coulomb friction, rigorously models the elastic deformation of the rolls and the frictional traction at the interface. In contrast with classical theories (3) it is shown that, for gauges less than a critical value, plastic reduction takes place in two zones, at entry and exit, which are separated by a neutral zone in which the rolls are compressed fiat and there is no slip between the rolls and the strip. Roll load and torque are governed by five independent non-dimensional parameters which express the influence of gauge, reduction, friction and front and back tensions. Values of load and torque have been computed (for zero front and back tensions) for a wide range of thickness, reduction and friction and have been found to collapse approximately on to a single master curve.
124 citations
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IBM1
TL;DR: In this article, a series of wear experiments utilizing a ball-plane configuration was performed to determine the influence of both the magnitude and anisotropy of the surface roughness on wear.
78 citations
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TL;DR: In this paper, the influence of roll radius on roughness transfer in skin-pass rolling is investigated by experimental rolling tests as well as numerical analysis by elastic-plastic FEM.
42 citations