A Reliability-Based Approach to Flatness Actuator Effectiveness in 20-High Rolling Mills

2012 ◽  
Author(s):  
Arif Malik ◽  
John Wendel ◽  
Mark Zipf ◽  
Andrew Nelson
Keyword(s):  
Rolling Force ◽  
Thin Sheet ◽  
Small Diameter ◽  
Global Market ◽  
Distribution Data ◽  
Control Mechanisms ◽  
Rolling Mills ◽  
Strip Flatness ◽  
Control Quality ◽  
Flatness Control

20-High rolling mills process high strength and/or very thin non-ferrous and ferrous metals using a complex, cluster arrangement of rolls. The 20-high roll cluster arrangement achieves specific flatness goals in the thin sheet by delivering maximum rolling pressure while minimizing the deflections of the small diameter rolls. 20-high mills also employ flatness control mechanisms with sophisticated actuators, such as those to shift intermediate rolls and deflect backup bearing shafts. The purpose of this is to compensate for variations in strip dimensional and mechanical properties which can cause poor flatness control quality from discrepancies in work-roll gap profile and distribution of rolling force. This suggests that the random property differences in the rolling parameters that substantially affect the flatness must be directly accounted for in flatness control algorithms in order to achieve strict flatness quality. The use of accurate mathematical models that account for the rolling pass target gage reduction can optimize the flatness control actuators and help gain an advantage in the thin gauge strip competitive global market. Based on the expected process parameter variations and nominal mill set-points (speed, tension, gage reduction, etc.), the mill’s process control computer should determine the probability that target flatness control quality will be met for a required length of strip. The process computer should then either modify the number of rolling passes or adjust the thickness reduction schedule before rolling begins to secure an improved flatness probability estimate if the probability of achieving target strip flatness is too low for the required deliverable quality. Therefore, this research integrates 1) 20-high roll-stack mill mathematical modeling, 2) probability distribution data for random important rolling parameters, 3) reliability-based models to predict the probability of achieving desired strip flatness, and 4) optimization examples. The results can be used to reduce wasted rolled metal from poor flatness before rolling.

Reliability-Based Optimal Cluster Mill Pass Scheduling

2011 ◽  
Author(s):  
Arif Malik ◽  
John Sanders ◽  
Ramana Grandhi ◽  
Mark Zipf
Keyword(s):  
Rolling Force ◽  
Mixed Finite Element ◽  
Rolling Process ◽  
Global Market ◽  
Rolling Mills ◽  
Rolling Pass ◽  
Strip Flatness ◽  
Pass Schedule ◽  
Flatness Control ◽  
Cluster Type

Optimal pass-scheduling on cluster-type cold rolling mills, use to process flat metals, presents added challenges over conventional (vertical-stack) mills due to the complexity of roll arrangements. Cluster-type rolling mills not only pose difficulties in modeling deflections occurring in the multi-roll stack, they also impose the burden of modeling more sophisticated mechanisms used to adjust rolling force distribution and achieve desired strip flatness. In a competitive global market for very thin gauge strip, an advantage is gained through use of efficient mathematical set-up models that can adequately optimize the flatness actuators according to the target gauge reductions for each rolling pass. The mill’s process control computer should therefore determine a gauge reduction schedule leading to minimum number of passes, while simultaneously assigning nominal flatness control actuator set-points. Although recent developments in roll-stack deflection modeling using simplified, mixed finite element techniques have enabled more efficient roll-stack deflection modeling in 20-high and other cluster mills, the optimal pass-schedule problem is still complicated by the abundance of geometric and mechanical property variations in the strip or sheet to be processed. Furthermore, problems with strip flatness frequently arise because of uncertainties in roll diameter profiles resulting from variations in the roll grinding and roll wear patterns. In this paper, we extend recent work in pass schedule optimization (through improved rollstack deflection) by applying First Order Reliability Methods to rigorously account for various rolling process uncertainties. The results allow predictive probability constraints for strip flatness to be included in the optimization problem, thus enabling mill operators some insight and control into the likelihood of achieving desired strip flatness for a given rolling pass schedule.

An Advanced Strip Flatness Forecast and Simulation System for Hot Tandem Mill

2011 ◽  
Vol 291-294 ◽  
pp. 469-474
Author(s):  
Dong Cheng Wang ◽  
Hong Min Liu
Keyword(s):  
Rolling Force ◽  
Control Level ◽  
Simulation System ◽  
Control Technology ◽  
Independent Innovation ◽  
Development Platform ◽  
Strip Flatness ◽  
Technology Improvement ◽  
Flatness Control ◽  
Roll Shape

Taken hot tandem mill as research object, based on complete flatness control theary, in order to improve flatness control technology, an advanced strip flatness forecast and simulation system for hot tandem mill is developed through theoretical analysis, mathematical modeling, computer simulation and industrial validation. The simulation system’s outputs include flatness, on-load roll gap, rolling force distribution, contact pressure between rolls, strip’s temperature evolution, thermal roll shape and roll wear shape, which can be applied to mill type selection, flatness control performance analysis, preset control, roll shape optimization, virtual rolling, and so on. The simulation system can provide research and development platform for flatness control technology’ improvement and independent innovation, and has important significance to improve the flatness control level of hot tandem mill.

Strip Flatness Mechanism Analysis in Single-Stand Cold Mills

2015 ◽  
Author(s):  
Feng Zhang ◽  
Arif S. Malik
Keyword(s):  
Peak Stress ◽  
High Strength ◽  
Mathematic Model ◽  
Strip Thickness ◽  
Control Mechanisms ◽  
Mechanism Analysis ◽  
Strip Flatness ◽  
Thickness Profile ◽  
Roll Bending ◽  
Flatness Control

Manufacturing high-strength and light-weight (thin gauge) sheet metals presents challenges in the cold rolling processes. Primary reasons are the difficult-to-predict effectiveness of the various flatness control mechanisms, and the associated evolution of roll stress amplitudes. The purpose of this paper is to demonstrate simulations that provide insights into the behavior of various sheet flatness control mechanisms, including roll bending and roll shifting on 4-high and 6-high single stand mills. An efficient, static mathematic model is utilized to analyze mill deflections, strip thickness profiles, and roll stresses. While appropriate roll ‘sizing’ is crucial in designing mills to be competitive for intended products, this requires practical insights into flatness mechanism behavior and peak roll stress characteristics. The knowledge gained from the simulations in this work can assist in interpreting results of automated computational sizing optimization models. Further, it may provide better understanding of general mill deflection behaviors, and help identify interesting situations such as when the peak stress location changes, or wedge type strip thickness profile effects are induced incidentally by specific flatness control mechanisms.

Calculation and Analysis of Tandem Cold Rolling Force Parameters

2014 ◽  
Vol 1004-1005 ◽  
pp. 1109-1113
Author(s):  
Jin Lan Bai ◽  
Hong Zhi Pan
Keyword(s):  
Tensile Stress ◽  
Cold Rolling ◽  
Rolling Force ◽  
Measured Data ◽  
Strip Flatness ◽  
Tandem Cold Rolling ◽  
Thermal Crown ◽  
Flatness Control ◽  
Arc Lengths ◽  
Contact Arc

In order to improve the accuracy of rolling force parameters,the elastic deformation and pressure between rolls of tandem cold rolling are calculated using divided element method in this paper. Bland-Ford model is used to calculate the rolling force, and the lengths of flattening contact arcs of each element are calculated. Considering the flattening contact arc lengths and tensile stress synthetically, rolling force parameters are calculated iteratively. Then the corresponding procedure is developed, and the distribution of rolling force, pressure between rolls and tensile stress are calculated with this procedure. The results are basically consistent with the measured data, and it will be useful to thermal crown calculation and strip flatness control.

A Flatness Control System Design Based on Actuator Efficiency Factors for Cold Rolling Mill

2010 ◽  
Vol 139-141 ◽  
pp. 1889-1893 ◽  
Author(s):  
Peng Fei Wang ◽  
Dian Hua Zhang ◽  
Xu Li ◽  
Jia Wei Liu
Keyword(s):  
Control System ◽  
Rolling Force ◽  
Quantitative Description ◽  
Learning Model ◽  
Feed Forward Control ◽  
Flatness Control ◽  
Stand Type ◽  
Loop Feedback ◽  
Efficiency Factors ◽  
Self Learning

In order to improve the flatness of cold rolled strips, strategies of closed loop feedback flatness control and rolling force feed forward control were established respectively, based on actuator efficiency factors. As the basis of flatness control system, efficiencies of flatness actuators provide a quantitative description to the law of flatness control. For the purpose of obtaining accurate efficiency factors matrixes of actuators, a self-learning model of actuator efficiency factors was established. The precision of actuator efficiency factors could be improved continuously by correlative measurement flatness data inputs. Meanwhile, the self-learning model of actuator efficiency factors permits the application of this flatness control for all possible types of actuators and every stand type. The developed flatness control system has been applied to a 1250mm single stand 6-H reversible UCM cold mill. Applications show that the flatness control system based on actuator efficiency factors is capable to obtain good flatness.

Influence of Roll Profile Configuration on High-Strength Strip Flatness Control Performance in Tandem Cold Rolling

2010 ◽  
Vol 145 ◽  
pp. 210-215 ◽  
Author(s):  
Jie Wen ◽  
Qing Dong Zhang ◽  
Xiao Feng Zhang ◽  
Xue Wei Ye
Keyword(s):  
Cold Rolling ◽  
High Strength ◽  
Industrial Applications ◽  
Fem Model ◽  
Roll Profile ◽  
Strip Flatness ◽  
Flatness Control ◽  
Pressure Peak ◽  
Tandem Cold Mill ◽  
Roll Gap

According to the characteristic of high-strength strip, the roll profile configuration and change of CVC tandem cold mill are analyzed. Through the establishment of FEM model, the influences of three representative forms of roll profile configuration on high-strength strip flatness control in CVC cold rolling mill are compared, which are conventional back-up roll / CVC intermediate roll, back-up roll with CVC compensation / CVC intermediate roll, VCL+ back-up roll / HVC intermediate roll. Compared with the other two roll profile configuration, the configuration of VCL+ back-up roll / HVC intermediate roll increases 26.74% in crown adjustment domain of roll gap and 22.09% in lateral stiffness of roll gap, decreases 27.43% in contact pressure peak values between rolls. The new roll profile configuration has obtained industrial applications. Production data indicate that the control accuracy of high-strength strip is improved, also the wear of back-up roll. Significant application results have been achieved.

scholarly journals IMPROVEMENT OF TECHNOLOGICAL PROCESS OF DRILLING THIN SHEET STEELS

2020 ◽  
pp. 48-54
Author(s):  
Anatoliy Ostrovsky
Keyword(s):  
Sheet Metal ◽  
Technological Process ◽  
Agricultural Sector ◽  
Sheet Material ◽  
Thin Sheet ◽  
Small Diameter ◽  
Main Tool ◽  
Drilling Process ◽  
Different Diameters ◽  
The Right

This article considers the technological process of drilling holes in sheet metal. The existing typical technological process, with detailed analysis, provides grounds for substantiating the idea of an innovative solution. There is a connection between the improvement of economic indicators of this technological operation with the change of geometric parameters of the tool. The comparison of existing technological processes, operations, and transitions of production of round openings with the use of spiral drills is given. The traditional technique involves a clear sequence of the technological process with the use of tools for marking, kerning, and sequential use of screw drills of different diameters. Therefore, after the previous operation of marking the center of the two holes, perform the operation of kerning. The core (recess in the metal) prevents the deviation of the small diameter screw drill from the marking lines. After the above steps, the traditional technological process involves drilling a small diameter hole in order to direct the main tool in the right direction. To make the main hole perform special sharpening of the working part of the twist drill so that the diameter of the Central part of the tool is equal to the diameter of the first guide hole to avoid further displacement of the main hole and the next operation is to drill the hole to the desired diameter. As a result, the article raises the topic, given the widespread use of sheet metal, including in the agricultural sector, the feasibility of using an innovative idea to improve the technological process associated with the processing of sheet material, namely thin metal sheets. It is worth noting that for example, we consider a material that is characterized by its versatility, namely steel Ст 3. Despite the numerous sources devoted to the study of improving the drilling process, there are a number of issues, including the extension of this direction surfaces with a covering and without it, various thicknesses within the thin-walled hire. The most significant result of the improved technological process of drilling will be used in the system of efficient maintenance of agricultural machinery.

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