Research on Behavior of Slab Surface Defects in Forward Slip Zone during V-H Rolling Process

2008 ◽  
Vol 575-578 ◽  
pp. 243-248 ◽  
Author(s):  
Hai Liang Yu ◽  
Xiang Hua Liu ◽  
Chang Sheng Li ◽  
Li Qing Chen
Keyword(s):  
Contact Pressure ◽  
Surface Defects ◽  
Rolling Direction ◽  
Longitudinal Crack ◽  
Crack Tip ◽  
Rolling Process ◽  
Slab Surface ◽  
Forward Slip ◽  
Significant Information ◽  
Forward Slip Zone

Behavior of the transversal crack and the longitudinal crack on slab surface during V-H rolling was simulated by the FEM. The contact pressure on crack surfaces and the crack-tip stress change rules during rolling were analyzed. Results show that the contact pressure on crack surfaces decreases and the tensile stress appears at crack tip in the zone of slippage on the delivery side, which may make the cracks propagation. For the phenomenon, the stress distribution along rolling direction and along width direction in rolling are analyzed, and the influence of forward slip on the closure and growth of the surface transversal crack and the surface longitudinal crack are discussed. Results support some significant information for researching the behavior of the slab surface defects in rolling process.

scholarly journals Investigating the Contact Responses of the Roller Cavity Surfaces in the Compressor Blade Rolling Process

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qichao Jin ◽  
Wenhu Wang ◽  
Ruisong Jiang
Keyword(s):  
Shear Stress ◽  
Contact Pressure ◽  
Rolling Process ◽  
Compressor Blade ◽  
Rolling Contact ◽  
Slip Zone ◽  
Sliding Velocity ◽  
Forward Slip ◽  
Forming Process ◽  
Forward Slip Zone

The investigation of the contact responses is the key for evaluating the local wear of dies in the plastic forming process. This paper investigated the contact load distributions and evolutions of the roller cavities in the compressor blade rolling process by the FEM. It was the first study to quantify the distributions and evolutions of the contact responses for rolling irregular components. The results indicated that the maximum contact pressure is generally present at the center of the contact interfaces, and the magnitudes of contact pressure decreased with evolution of the blade rolling process. The rolling contact interfaces can be divided into the backward slip zone, the stick zone, and the forward slip zone based on the shear stress distributions. The stick zone was a narrow belt which separated the forward and the backward slip zone, and the shear stress in the stick zone was nearly zero. The shear stress magnitudes in the forward slip zone were smaller than those in the backward slip zone, and the directions of shear stress in forward and backward slip zones were adverse. The magnitudes of shear stress over the forward and backward slip zones decreased with evolution of the blade rolling process. The distributions of local sliding were in a V-shape, the local sliding in the stick zone was nearly zero, and the bigger sliding in backward and forward slip zones was present at the boundaries of rolling entrance and exit sections. The local sliding velocity magnitudes in the backward slip zones were always bigger than those in the forward slip zones, and the magnitudes of local sliding at the rolling entrance sections were bigger than those at the rolling exit sections. In general, the local sliding velocity magnitudes increased firstly and decreased sharply at 2T/3. The current paper develops the distributions and evolutions of contact responses in the blade rolling process. The contact responses can be used for studying the wear of roller cavities to avoid the accuracy inconsistency of the shaped blade.

Simulative Study of Evolution Behavior of Transverse Surface Crack in Rolling Process

2011 ◽  
Vol 403-408 ◽  
pp. 88-92
Author(s):  
Ya Gao ◽  
Jian Lin Sun ◽  
Bing Yun
Keyword(s):  
Tensile Stress ◽  
Surface Crack ◽  
Rolling Direction ◽  
Crack Tip ◽  
Element Model ◽  
Rolling Process ◽  
Friction Coefficients ◽  
High Crack ◽  
Explicit Finite Difference ◽  
Evolution Behavior

Based on explicit finite difference algorithm, finite element model of steel plate with transverse surface crack in rough rolling was found. The evolution regularity of transverse surface crack in rolling process was calculated with the model, and effect of different crack sizes, different friction coefficients and different roll diameters on crack evolution were studied. The research indicated that, in rolling direction, the crack tip stress changed from tensile stress to compression stress and then tensile stress again; length and depth of crack both had effect on the healing and propagation of the crack, and mostly in the way of influencing displacement of freedom surface of the crack; different friction coefficients showed no effect on crack tip propagation, but low friction coefficient would be in favor of crack healing at crack bottom; small roll diameter would lead to high crack tip tensile stress and more propagation at crack tip.

Texture Control of Aluminum and Magnesium Alloys by the Symmetric/Asymmetric Combination Rolling Process

2011 ◽  
Vol 702-703 ◽  
pp. 68-75 ◽  
Author(s):  
Hirofumi Inoue
Keyword(s):  
Rolling Direction ◽  
Solution Treatment ◽  
Rolling Process ◽  
Warm Rolling ◽  
Fiber Texture ◽  
Drawing Ratio ◽  
Asymmetric Rolling ◽  
Automotive Body ◽  
Solution Treated ◽  
Aluminum And Magnesium Alloys

In order to develop favorable textures for deep drawing of Al-Mg-Si and Mg-Al-Zn alloys that are promising as automotive body panels, we have adopted the symmetric/asymmetric combination rolling (SACR) process consisting of conventional symmetric rolling and subsequent asymmetric rolling at relatively low reduction. The combination of symmetric cold rolling and asymmetric warm rolling for AA6022 sheets leads to the formation of “TD-rotated β-fiber texture”, resulting in the evolution of {111} recrystallization texture after solution treatment at a high temperature. The SACR processed and solution-treated sheets show a high average r-value with small in-plane anisotropy, and consequently the limiting drawing ratio increases significantly, compared to that of the cold-rolled and solution-treated sheets. In the case of AZ31 magnesium alloy, the SACR process by hot rolling causes the formation of a unique texture, which shows two (0001) poles with tilt angles of 0 and −40 degrees from the normal direction (ND) toward the rolling direction (RD). In addition, subsequent annealing weakens intensity of the double-peak texture, so that the drawability is greatly improved in comparison with that of the conventional warm-rolled sheets with a strong basal texture. At the same time, yield strength decreases to some extent, but the SACR processed and annealed sheets exhibit a good balance of strength and formability due to a mixed texture with basal and tilt components.

Study on the Microstructure and Texture of Warm Rolled ZK60 Magnesium Alloy Sheet

2012 ◽  
Vol 557-559 ◽  
pp. 1344-1348
Author(s):  
Hong Mei Chen ◽  
Hua Shun Yu ◽  
Guang Hui Min ◽  
Yun Xue Jin
Keyword(s):  
Shear Bands ◽  
Rolling Direction ◽  
Rolling Process ◽  
Warm Rolling ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Rolling Reduction ◽  
Basal Pole ◽  
Zk60 Alloy ◽  
Twin Roll

The microstructure and macrotexture of ZK60 alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast ZK60 alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled ZK60 alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.

Optimization of Rolling Modes on the Mill 1700 of JSC "ArselorMittal Temirtau" with Aim to Increase Quality of Sheet Rolled Products

2015 ◽  
Vol 1095 ◽  
pp. 786-794
Author(s):  
A.B. Naizabekov ◽  
V.A. Talmazan ◽  
S.N. Lezhnev ◽  
E.A Panin ◽  
А.S. Erzhanov ◽  
...  
Keyword(s):  
Surface Defects ◽  
Mechanical Damage ◽  
Rolling Process ◽  
Rolled Sheet ◽  
Strip Rolling ◽  
Technological Factors ◽  
Second Stage ◽  
Sheet Surface ◽  
Cold Rolled

Used the influence of technological factors of the rolling process on the intensity of the rolling out of the defect to determine the value of deformation and the coefficient of use of the plasticity resource. Introduced the notion of residual coefficient of plasticity resource in the second stage of transformation of the defect. Found that the causes of deterioration of the quality of cold-rolled sheet can be numerous defects of mechanical origin, caused by mechanical damage of the sheet surface. Conducted an analysis of profiles rolling modes, rolled on the mill 1700. With the use of existing methods calculated DUPR on workshop modes of rolling of specified profiles with and without considering the surface defects. Carried an optimization of the modes of strip rolling with surface defects.

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.

Numerical simulation of slab deformation process with different reduction values in vertical rolls of mill 2000 roughing stands

2021 ◽  
Vol 77 (6) ◽  
pp. 675-681
Author(s):  
N. L. Bolobanova ◽  
E. A. Garber
Keyword(s):  
Process Model ◽  
Surface Defects ◽  
Numerical Study ◽  
Rolling Process ◽  
Rolled Stock ◽  
Metal Consumption ◽  
Wide Face ◽  
Total Reduction ◽  
Hot Rolling Mill ◽  
Deform 3D

Perfection of rolled stock production processes at continuous wide-strip hot rolling mill (CWHRM) aimed at minimization of metal consumption, is an effective mean to decrease its cost. In the process of slabs rolling at CWHRM, the metal consumption is stipulated first of all by complicated workpiece forming in roughing stands during consecutive reduction by vertical and horizontal rolls. Results of the numerical study of slab deformation with different values of reduction in vertical rolls of roughing stands of mill 2000 are presented. The implementation of rolling process model based on application of DEFORM-3D program of finiteelement analysis described for evaluation of metal shifting from the edges of slab in the direction of the middle of the width. The convergence of the simulation results with the measurements data of workpiece forming during roughing rolling at Severstal mill 2000 was experimentally confirmed. It was found that an increase of reduction in vertical rolls has no significant effect on the metal shifting from a narrow edge to a wide one. Increase the total reduction in vertical rolls leads to an unfavorable stress-strain state of the edge region and the Cockcroft–Latham criterion rises by 20–30%. It was proposed to reduce the total reduction in the vertical rolls of the roughing stands of mill 2000 down to 40–50 mm. It was shown that increase of time of slab moving from the heating furnace to the scale breaker causes growth the Cockcroft-Latham criterion and does not affect the amount of metal shifting from a narrow face to a wide one. The proposed method of simulation the process of slab deformation in the roughing group of the mill 2000 proved by results of industrial rolling can to be used for further study of the effect of rolls profiling and forming of surface defects with the provision of minimal metal shifting onto a wide face.

An Efficient Way of Calculating Temperatures in the Strip Rolling Process

1998 ◽  
Vol 120 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Der-Form Chang
Keyword(s):  
Heat Transfer ◽  
Rolling Direction ◽  
Rolling Process ◽  
Strip Rolling ◽  
One Dimensional ◽  
Lubrication Regimes ◽  
Real Area Of Contact ◽  
Lagrangian Coordinate ◽  
Efficient Heat Transfer ◽  
Real Area

The two-dimensional heat transfer between the strip and rolls in strip rolling is modeled by one-dimensional heat conduction equations adopting Lagrangian coordinate systems on the contact surfaces. Finite difference formulations are used in the rolling direction and analytical solutions are applied normal to this direction, making computation more efficient. Heat transfer in the sticking region is considered. The influence of real area of contact on heat transfer is also taken into account, resulting in a method capable of modeling the strip rolling process operated in any of several different lubrication regimes. This method provides good temperature predictions.

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