Thin Gauge Strip Research Articles

Calculation method and analysis of residual stress in the strip bending roller straightening process

Taking thin gauge strip as an example, the deformation process of metal strip in bending roll straightening was studied. Based on the theory of discrete, curvature integral and elastic–plastic mechanics, the strip travel trajectory of the bending roll straightening process is analyzed, and the numerical analytical calculation method of the continuous straightening process of the strip bending roll is established. The results are verified by establishing MARC finite element simulation and designing straightening experiment. The effects of yield strength, plastic rate and bending amount on residual stress after straightening were studied. In the straightening process, with the increase of the amount of bending roll, the residual strain converges to the region Γ, and with the increase of the yield strength, the region Γ decreases. With the increase of the yield strength, the amount of bending roll and the plastic rate, the wave height increases. The results of the calculation of residual stress, finite element simulation and experiment are close and the trend is consistent. The results show that the logic of the calculation method is reasonable, and the prediction error is within the scope of engineering application, which is helpful to the realization of process intelligence in the process of bending roller straightening.

Rolling Schedule Multi-objective Optimizationbased on Influence Function for Thin Gauge Steel Strip in Tandem Cold Rolling

The setting of rolling schedule in tandem cold mill is one of the most crucial content in rolling process, which will have a direct impact on product quality and production efficiency. According to the actual requirements in the rolling process, a multi-objective function based on influence function method was built. The objective function was aimed specially at thin gauge strip and solved by Tabu search algorithm. Meanwhile, in order to avoid the strip slipping by the reduction of friction coefficient, the tension schedule was corrected according to the rolling length of work roll. The proposed optimization method has been applied successfully to a 1450mm 5-stand tandem cold mill. Application results show that the optimized rolling schedules are more close to the actual requirements and the flatness quality is improved greatly.

Arvedi ESP for High-Quality Hot-Strip Production at Rizhao Steel

With five Arvedi ESP lines, Rizhao Steel in China is now focusing on the highly attractive local and export markets for high-quality, thin-gauge strip products. The first lines began operations in 2015.High-strength but lightweight car bodies, ultra-thin structures paired with the highest tensile strength – and all at the lowest production costs. Innovative processes are required in order to fulfil the demands of the car and metals industries. With precise thermo-mechanical rolling and rigorous temperature guidance in the narrowest possible operations windows Arvedi ESP opens the door to producing demanding steel grades in the shortest implementation times and at reduced alloying costs. Low operation costs are also provided by efficient induction heating and the resulting energy savings.This paper presents the ESP plant setup of Rizhao Steel as well as the training and support program. Additionally the potentials of AHSS production with ESP will be described by referencing the results of the first ESP plant in operation since 2009 at Arvedi Steel, Italy, and the ESP plants of Rizhao steel.

Development and application of roll contour configuration in temper rolling mill for hot rolled thin gauge steel strip

In order to improve the flatness of hot rolled thin gauge steel strip, a new type of roll contour configuration was developed for a four-high temper rolling mill based on the finite element method analysis. The roll contour configuration consists of a variable contact back-up roll contour and a positive crown work roll contour. Both can be described as sixth order polynomial functions. The variable contact back-up roll not only reduces the roll stack deflection and contact stress concentration between work and back-up rolls, but also increases the control capability of the bending force of the work roll. Positive crown work roll contour is utilised to compensate roll wear and in turn the length of temper rolling schedule can be prolonged. After this roll contour configuration was applied on the temper rolling mill of Qiangang Company of Shougang Group, the flatness of hot rolled thin gauge strip was improved by 10% and the working efficiency was also increased as the length of temper rolling schedule was increased.

Analysis of Advanced Strip Shape during Cold Rolling of Thin Strip

The demand of thin gauge strip with good quality such as the strip shape and surface finish is significantly increasing. In this study, finite element model of the strip shape during cold rolling of thin strip in asymmetrical rolling was developed, and the finite element simulation of the thin strip shape has been carried out in LS-DYNA. The effects of reduction and speed ratio on the strip shape and profile and the strip edge drop have been obtained. The developed finite element model has been verified with the experimental data. The obtained results are applicable to the control of the rolled thin strip shape in rolling practice.

Prediction of slug carry-up by the punch in blanking by air-blow of the slug

Blanking is one of the press working operations most often encountered in sheet-metal processing. The punched part or slug which should fall down through the die cavity was occasionally brought upward by the punch and dropped on the strip stock which will hinder the following blanking operation. Though there are many ways to reduce this problem, however, this phenomenon still exists when stamping a very thin gauge strip in a high-speed press. Methods which can help us predict the occurrence of the slug suck-up by the punch in blanking are thus important. In this study, a prediction method is proposed for the occurrence of the phenomenon by air-blow of the slug. Parameters like material tensile strength, punch/die clearances, punch chamfer degree, punch corner radius were considered in organizing the experiment plans. The results showed that the slug carry-up forces measured from direct air-blow of the slug can be adopted as a criterion for the occurrence of the phenomenon. The best and worst parameter combinations were also identified by this method.

Prediction of hysteresis loop in magnetic cores using neural network and genetic algorithm

The dynamic hysteresis loops of a range of soft magnetic toroidal wound cores made from 3% SiFe 0.27 mm thick M4, 0.1 and 0.08 mm thin gauge strip have been measured over a wide frequency range (50–1000 Hz). A dynamic hysteresis loop prediction model using neural network and genetic algorithm from measurements has been developed. Input parameters include the geometrical dimensions of wound cores, peak magnetic induction, strip thickness and magnetizing frequency. The developed neural network for the estimation of hysteresis loops has been also compared with the dynamic Preisach model and Energetic model. The results show that the neural network model trained by genetic algorithm has an acceptable prediction capability for hysteresis loops of toroidal cores.

Quality strip production with a high speed medium thick slab caster

A high quality strip production process has been established, using the high speed medium thickness slab caster developed by Sumitomo Metals and Sumimoto Heavy Industries. North Star/BHP Steel and TRICO Steel in the USA have successively started up a machine in 1997. Stable casting of 900-1650 mm wide and 70-90 mm thick slabs at 5.0 m/min has been achieved. Thin gauge strip with excellent surface quality has been obtained.

Cold Rolling of Foil

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.