scholarly journals A computational method for pass design of the four-roll rolling process for sizing of round sections

2021 ◽  
Author(s):  
Christian Overhagen
Keyword(s):  
Design Method ◽  
Rolling Process ◽  
Initial Section ◽  
Computational Method ◽  
Lateral Spread ◽  
Suitable Model ◽  
Pass Design ◽  
Cross Sectional ◽  
Rolling Mills ◽  
Single Radius

The four-roll rolling process (4RP) enables the further evolution of sizing processes in rolling mills for round sections. The well-known advantages of the three-roll process over the two-roll process can be further improved using the 4RP. The participation of four rolls in the deformation zone instead of three or two leads to a significant increase in deformation efficiency. The present work shows a pass design method for pass sequences in the four-roll rolling process. Here, three basic types of roll groove geometries are discussed: the flat groove, the non-opened single-radius groove, and a tangentially opened type of a single radius groove. Based on a predefined cross-sectional evolution, grooves are found numerically to satisfy two conditions, i.e., the cross section of the rolled section and the groove filling criterion. The equations of the equivalent pass method, together with a suitable model for lateral spread and the geometric equations of the groove are solved by nonlinear optimization to minimize the sectional and filling errors of a specific pass. Combined for several rolling passes, a complete pass design can be carried out for the reduction of a specified initial section to a final section. The presented results show, how a pass design method for the four-roll rolling process can be constructed. The newly developed model is implemented in a software solution for pass design and analysis of full section rolling mills. An exemplified pass design is discussed to show the possibilities and limitations of the new model.

A New Rolling Model for Three-Roll Rolling Mills

2014 ◽  
Vol 622-623 ◽  
pp. 879-886 ◽  
Author(s):  
Christian Overhagen ◽  
Paul Josef Mauk
Keyword(s):  
Design Method ◽  
Rolling Process ◽  
Slab Method ◽  
Pass Design ◽  
Upper Bound Theorem ◽  
Rolling Mills ◽  
Rolling Industry ◽  
Wide Range ◽  
Bound Theorem ◽  
Set Up

During the last 90 years, a lot of works have been published about rolling theories for the two-roll rolling process (2RP). In the last decades, the three-roll process (3RP) has become a significant technique in the production of wire rod and bars, as it allows to cover a wide range of finished dimensions with one pass design, or to realize very close tolerances, depending on the pass design method used (free size rolling or high precision rolling). Horihata and Motomura [2] made use of the upper bound theorem to construct a method for spread calculation, but up to now, a straightforward mathematical method for calculation of stress distribution, roll forces, torques and forward slip is still missing. The present paper aims at a transfer of the slab method, which is well-known and established for the 2RP, to the 3RP. After the rolling theory for flat passes is introduced, Lendl’s equivalent pass method is transferred to the 3RP, which allows the calculation of section passes. Computational results show, that roll forces, torques and forward slips can be calculated under inclusion of elastic stand feedback and interstand tensions. Therefore the model can be used for roll speed set-up to minimize interstand tensions, which is of great importance for the rolling industry.

Roll design method using virtual flow line for multi-stage profile rolling process

2018 ◽  
Vol 32 (10) ◽  
pp. 4813-4819
Author(s):  
Hyeon-Seok Jung ◽  
Jeong-Hun Kim ◽  
Byung-Min Kim
Keyword(s):  
Flow Line ◽  
Design Method ◽  
Rolling Process ◽  
Roll Design ◽  
Multi Stage

scholarly journals The Analysis of the Asymmetric Plate Rolling Process in the Finishing Stand 3600/ Analiza Asymetrycznego Procesu Walcowania Blach Grubych W Klatce Wykańczającej 3600

2014 ◽  
Vol 59 (4) ◽  
pp. 1533-1538
Author(s):  
A. Kawałek ◽  
H. Dyja ◽  
M. Knapinski ◽  
G. Banaszek ◽  
M. Kwapisz
Keyword(s):  
Process Parameters ◽  
Rotational Speed ◽  
Shape Factor ◽  
Rolling Process ◽  
Asymmetry Factor ◽  
Asymmetric Rolling ◽  
Rolling Mills ◽  
Plate Rolling ◽  
Strip Shape ◽  
Roll Gap

Abstract In order to enhance the quality of plates, various solutions are being implemented, including normalizing rolling, the process of rolling followed by accelerated cooling, as well as new roll gap control systems. The hydraulic positioning of rolls and the working roll bending system can be mentioned here. The implementation of those systems results in increased loads of the rolling stands and working tools, that is the rolls. Another solution aimed at enhancing the cross-sectional and longitudinal shape of rolled plate is the introduction of asymmetric rolling, which consists in the intentional change of the stress and strain state in the roll gap. Asymmetric rolling systems have been successfully implemented in strip cold rolling mills, as well as in sheet hot rolling mills. The paper present results of studies on the effect of roll rotational speed asymmetry and other rolling process parameters on the change in the shape of rolled strip and the change of rolls separating force for the conditions of normalizing rolling of plates in the finishing stand. The variable process parameters were: the roll rotational speed asymmetry factor, av; the strip shape factor, h0/D; and the relative rolling reduction, ε. Working rolls of the diameter equal to 1000 mm and a constant lower working roll rotational speed of n = 50 rpm were assumed for the tests. The asymmetric rolling process was run by varying the rotational speed of the upper roll, which was lower than that of the lower roll. The range of variation of the roll rotational speed factor, av =vd/vg, was 1.01÷1.15. A strip shape factor of h0/D = 0.05÷0.014 was assumed. The range of rolling reductions applied was ε = 0.08÷0.50. The material used for tests was steel of the S355J2G3 grade. For the simulation of the three-dimensional plastic flow of metal in the roll gap during the asymmetric hot rolling of plates, the mathematical model of the FORGE 2008 ® program was used. For the mathematical description of the effect of rolling parameters on the strip curvature and rolls separating force the special multivariable polynomial interpolation was used. This method of tensor interpolation in Borland Builder programming environment was implemented. On the basis of the carried out analysis can be state, that by using the appropriate relative rolling reduction and working roll peripheral speed asymmetry factor for a given feedstock thickness (strip shape ratio) it is possible to completely eliminate the unfavorable phenomenon of strip bending on exit from the roll gap, or to obtain the permissible strip curvature which does not obstructs the free feed of the strip to the next pass or transferring the plate to the accelerated plate cooling stations. Additionally by introducing the asymmetric plate rolling process through differentiating working roll peripheral speeds, depending on the asymmetry factor used, the magnitude of the total roll separating force can be reduced and, at the same time, a smaller elastic deflection of rolling stand elements can be achieved. As a result smaller elastic deflection of the working rolls, smaller dimensional deviations across its width and length finished plate can be obtained.

scholarly journals IMPROVING DYNAMIC REGIME OF ROLLING FOR INCREASING DURABILITY OF BALL-ROLLING MILL ROLLS

2019 ◽  
Vol 61 (12) ◽  
pp. 927-932 ◽  
Author(s):  
V. Yu. Rubtsov ◽  
O. I. Shevchenko ◽  
M. V. Mironova
Keyword(s):  
Contact Pressure ◽  
Rotational Speed ◽  
Rolling Mill ◽  
Experimental Studies ◽  
Rolling Process ◽  
Operating Conditions ◽  
Frequency Method ◽  
Rolling Mills ◽  
Ball Rolling ◽  
Progressive Technology

One  of  the  important  reasons  for  the  downtime  of  ball  rolling  mills  is  replacement  of  rolls  due  to  their  wear  and  tear.  The  degree  and  zones  of  critical  wear  of  ball  rolling  rolls  are  investigated  in  the  article, where the greatest wear is observed over the flanges in zone of billet  capture.  Conditions  necessary  to  capture  the  blank  and  to  perform  rolling  process  are  analytically  determined.  Variable  frequency  method  of  roll  rotations  is  proposed  as  a  progressive  technology  for  blank supply. The results of tests for its variations in accordance with  linear  and  quadratic  law  are  presented.  Known  formulas  determining  average  strain  rate  at  rolls  rotational  speed  change  are  converted  for  linear and quadratic dependences. Experimental studies have been carried  out  in  conditions  of  EVRAZ  Nizhnetagilsky  Metallurgical  Plant  ball rolling mills during rolling of 60mm ball made of Sh-3G steel. Experiments  were  performed  for  given  parameters  of  manual  change  in  rolls rotation speed at blank capture by rollers. The results have shown  a  significant  effect  of  change  in  rotational  speed  on  average  specific  pressure during blank capture. Evaluation of torque-time and average  contact  pressure  for  calculated  and  experimental  data  are  presented.  Empirical characteristics are also described at variable rotational speed  of rolls according to linear and quadratic law. Acceptable convergence  of results of calculated and empirical characteristics is determined. Engineering solution has been proposed for that task. It consists in installation of a thyristor converter. This solution allows reduction of rolls  speed before blank capture. Also, this solution will increase frequency  to  the  nominal  value  according  to  the  given  law  after  blank  capture.  As an obtained result, there is uniform distribution of average contact  pressure over the entire length of the roll under different operating conditions  of  mill  in  automatic  mode. Application  of  this  technique  will  reduce wear degree of the rolling tool. At the same time, productivity  of ball rolling mill will be maintained. Rolls consumption and number  of rolls change will decrease due to rolls wear.

scholarly journals New Media and Crime among Adolescents in Anaocha LGA of Anambra Nigeria

2021 ◽  
pp. 65-78
Author(s):  
Chelsea C. Adogu ◽  
Henry N. Chineke ◽  
Prosper O. U. Adogu ◽  
Chika F. Ubajaka ◽  
Amara F. Chizoba ◽  
...  
Keyword(s):  
New Media ◽  
Media Use ◽  
Design Method ◽  
Simple Random Sampling ◽  
Psychological Trauma ◽  
Major Effect ◽  
Cyber Bullying ◽  
Cross Sectional ◽  
Anambra State ◽  
Media And Crime

New media use has been recently understood as an important issue to be looked into among adolescents, parents and others who deal with adolescents. This study sought to examine the new media and crime among adolescents in Anaocha Local Government Area of Anambra State. The study employed the cross-sectional descriptive design method involving a quantitative approach which included a survey of 224 adolescents between the ages of 13-19 years selected by cluster and simple random sampling techniques from five communities in the LGA. The instrument for data collection was interviewer-administered questionnaire while the Statistical Packages for Social Sciences (SPSS) was used in analyzing the data.  Findings revealed that phones were the most prevalent new media in use among adolescents particularly the male ones. Also, majority expressed negative view about the influence of the new media on adolescents, with sexting and cyber-bullying as the most common crimes associated with new media. Furthermore, psychological trauma was identified as the major effect of cyber-bullying on adolescent victims. This study recommended enlightenment of adolescents and other stakeholders in order to curtail the level of crimes committed through the new media. Parents and significant others are advised to keep a close watch on their adolescent children and wards while they are browsing the internet, and this will hopefully control criminal activities associated with new media use among adolescents in Anaocha LGA in particular and Nigeria in general.

Antecedents of Organizational Change and Its' Consequence towards Organizational Performance

2021 ◽  
Vol 9 (4) ◽  
pp. 261-272
Author(s):  
Lambas Marasi Tua LG ◽  
Kurniawati Kurniawati
Keyword(s):  
Transformational Leadership ◽  
Organizational Change ◽  
Organizational Commitment ◽  
Organizational Performance ◽  
Structural Equation ◽  
Positive Impact ◽  
Design Method ◽  
Positive Influence ◽  
Equation Model ◽  
Cross Sectional

Objective - The research was conducted to identify the positive influence of transformational leadership and organizational commitment towards organization change and the influence of change on learning and its' implication onorganizational performance. Methodology/Technique - The research design method is a hypothesis-testing approach. Units of research analysis areemployees of BUKU 3 and BUKU 4 Banks in Jakarta who have a supervisory function. The study data is cross-sectional obtained in a specified time period. Data was obtained through distributing online questionnaires containing statements to be responded with a minimum of 365 respondents required. Structural Equation Model was used to test the model of the research and AMOS software is used for data processing. Finding - The major finding of the research is that transformational leadership is not directly related to positive performance of the organization but more on how transformational leaders are able to manage organizational change that in the end will have a positive impact on organization performance.Organizational change also perceived has no positive impact on learning and learning also has no direct and mediating impact on positive organizational performance. Novelty - Type of Paper - Keywords: Change; Leadership; Organizational Commitment; Organizational Change; Organizational Learning; Organizational Performance.

scholarly journals Skew Rolling of Rods from Scrap Rail Heads

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2970 ◽  
Author(s):  
Tomczak ◽  
Pater ◽  
Bulzak
Keyword(s):  
Experimental Tests ◽  
Rolling Process ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Longitudinal Rolling ◽  
Rolling Mills ◽  
Second Stage ◽  
New Process ◽  
Skew Rolling ◽  
Theoretical Considerations

This paper presents the results of theoretical and experimental investigations of a new process of rolling rods from scrap rail heads. First, the industrial applications of scrap railway rails and methods of their recycling are discussed, and then the concept of two-stage rolling of rods from heads cut off from scrap rails is proposed. In the first stage of the process, a rail head preform was rolled in a hexagonal pass of a longitudinal rolling mill. Then in the second stage, the hexagonal bar was skew rolled into a rod in a helical roll pass. Theoretical considerations were based on finite element numerical modelling. The rolling process was simulated under 3D deformation using Forge NxT v.1.1 software developed by Transvalor Company. Calculations were carried out to determine the material flow kinematics, strength, and thermal parameters of the process and to identify the phenomena that might constrain its implementation. The numerical results were verified in experimental tests, during which preforms and rods were formed from scrap rail heads. The tests were conducted in longitudinal and skew rolling mills. The results indicate that rods can be effectively formed from scrap rail heads in just two steps. Rods obtained using the proposed method can be used as full-featured, semifinished products for the manufacture of various types of machine parts.

scholarly journals Study of Wire Deformation Characterization and Size Effects during the Micro-Flat-Rolling Process

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 405 ◽  
Author(s):  
Haibo Xie ◽  
Ken-ichi Manabe ◽  
Zhengyi Jiang
Keyword(s):  
Surface Roughness ◽  
Contact Area ◽  
Rolling Process ◽  
Lateral Spread ◽  
Curvature Radius ◽  
Element Simulation ◽  
Flat Rolling ◽  
Set Up ◽  
Rolling Deformation

A comprehensive research on the flat rolling deformation characterization of microwire has been conducted systematically through finite element simulation and testified by the results from the experimental analysis. The obtained results are compared in terms of lateral spread, geometrical characteristic, contact area width and surface roughness considering the effects of pass reduction and initial wire diameter. The size effect has been identified and surface layer modeling has been set up based on surface grain share and grain size distribution. The numerical method combined with varied flow stress has been verified by experimental value with a maximum difference of 3.7% for the 1.5 mm wire. With the increase of the height reduction, the curvature radius is decreased while the lateral spread and contact area width are increased. Surface roughness evolution in the range of 0.52–0.85 µm for the rolled wire has also been investigated.

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