CN113742975B - Method for predicting and evaluating head and tail defects of hot continuous rolling rough rolling vertical-horizontal rolling rolled piece - Google Patents
Method for predicting and evaluating head and tail defects of hot continuous rolling rough rolling vertical-horizontal rolling rolled piece Download PDFInfo
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Abstract
The invention belongs to the technical field of rolling, and particularly relates to a method for predicting and evaluating head and tail defects of a hot continuous rolling rough rolling vertical-horizontal rolling rolled piece. Aiming at the defects of the prior art, the invention provides a method for predicting and evaluating the head and tail defects of a vertical-horizontal rolling rolled piece in the hot continuous rolling rough rolling process, comprehensively considers the process procedures and actual equipment in the vertical-horizontal rolling process, establishes a finite element model based on field reality, sets experiment conditions by controlling a variable method to perform finite element simulation, establishes a function expression of key points of the head and tail defects of the vertical-horizontal rolling, fits the shape curve of the head and tail defects of the vertical-horizontal rolling rolled piece, and accordingly provides an evaluation method for the head and tail defects of the vertical-horizontal rolling rolled piece; the defects of the head and the tail of the rolled piece after vertical-horizontal rolling are accurately predicted, and the problem that the head and the tail of the rolled piece are difficult to determine in the production process is solved; meanwhile, an evaluation method of head and tail defects is provided. The invention can provide guidance for the subsequent shearing process and reduce the cutting loss rate.
Description
Technical Field
The invention belongs to the technical field of rolling, and particularly relates to a method for predicting and evaluating head and tail defects of a hot continuous rolling rough rolling vertical-horizontal rolling rolled piece.
Background
In order to improve the productivity and produce rolled products with various specifications, the continuous casting and rolling technology is rapidly developed, the on-line width adjusting technology is greatly developed, the continuous rolling efficiency is improved, and the continuous production is realized. The vertical-flat rolling is an important process of width adjustment, and because the deformation of the head and the tail of a rolled piece is not restricted in the length direction during the vertical roll rolling, the width of the head and the tail is shrunk, and fishtail-shaped defects are formed; during subsequent flat roll rolling, the fishtails at the head and the tail are aggravated, in the subsequent rolling process, the fishtail defects need to be removed by using flying shears, during shearing, because the defect shapes are not described, a proper shearing process is difficult to set, a part of shearing space needs to be reserved, waste is caused, and the yield is reduced.
In the hot continuous rolling rough rolling vertical-flat rolling stage, a plurality of patents are studied, and a Chinese patent CN 112439792A, a rough rolling width dynamic correction method based on the rolling force of a vertical roll, provides a method for dynamically correcting the width of a slab by calculating the deviation between the rolling force and the actual rolling force, and improves the width precision of rough rolling. Chinese patent CN 107185967A, a strip steel head and tail SSC short stroke control compensation method, proposes a short stroke control compensation method, which compensates for the fish tail shape of the head and tail of the strip steel to achieve the purpose of overcoming the head and tail curves. The Chinese patent CN 105930594A, a dog bone shape prediction method for a vertical rolling rolled piece, provides a method for predicting the cross section of a rolled piece after vertical rolling, and establishes a dog bone shape prediction curve by an analytical method, a function curve setting method and the like to predict the cross section of the rolled piece under different production conditions. In the above patent, the control method is used to control the width of the rolled piece, so as to achieve the purpose of improving the rough rolling precision. And the short stroke control is used, so that the head and tail width loss can be improved and reduced, and the purpose of reducing the cutting loss rate is achieved. However, the study on the dog bone was conducted only on the change in the thickness direction of the rolled piece. Influence factors of head and tail defects of rolled pieces after rolling are not deeply researched, and shapes of the head and tail defects are not accurately described.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for predicting and evaluating head and tail defects of a hot continuous rolling rough rolling vertical-horizontal rolling rolled piece. Simulating the opposite-flat rolling process by using finite element simulation software, analyzing influence factors of head and tail defects of the rolled piece, and respectively fitting the head and tail defects to achieve the purpose of predicting the shapes of the head and tail defects; and provides an evaluation method of head and tail defects. The numerical simulation method is a technology developed on the basis of finite element theory, is widely applied to the field of engineering, and can reduce the experiment cost and obtain data which are difficult to measure in the field through virtual experiments.
The method for predicting and evaluating the defects of the head and the tail of the hot continuous rolling rough rolling vertical-horizontal rolling rolled piece comprises the following steps:
a method for predicting head and tail defects of a hot continuous rolling rough rolling vertical-horizontal rolling rolled piece is shown in a flow chart 1 and comprises the following steps:
step 1: creation of finite element model
Step 1.1: in situ data acquisition
Acquiring equipment data and rolled piece data of a production field to obtain field data of a roller and a rolled piece, wherein the field data comprises a vertical roller diameter range, a vertical roller width adjusting range, a flat roller diameter range, a rolled piece initial width range, a rolled piece initial thickness range and a rolled piece initial lengthL 0 And a rolling speed range.
Step 1.2: building finite element model
Establishing a rough rolling process vertical-flat rolling finite element model by using finite element software;
the finite element model establishment comprises the following setting conditions:
according to the vertical-flat rolling characteristics, under the condition that the result is not influenced, in order to save calculation time, a width direction 1/2 model is established, and during modeling, a vertical roll and a flat roll are taken as rigid bodies, and a rolled piece is taken as an elastic plastic body;
utilizing finite element software to set material properties of the roller and the rolled piece, comprising: poisson's ratio, young's modulus, density, yield strength and tangent modulus, and the rolled piece material model adopts an isotropic hardening model;
and (3) meshing the model by using a finite element software meshing tool, wherein hexahedral meshes are preferably adopted in order to reduce the number of meshes.
Carrying out contact setting by using finite element software, wherein the contact type is automatic surface-surface contact, and contact setting objects are a vertical roll, a rolled piece, a flat roll and the rolled piece respectively;
carrying out boundary constraint setting by using finite element software, and setting a boundary in the width direction as a symmetrical boundary;
and (3) applying load by using finite element software, setting initial speed in the length direction of the rolled piece, and setting angular speed of the counter roll and the flat roll.
Step 2: finite element simulation analysis:
by the diameter of vertical rollerR E Width regulating delta of vertical rollerEDiameter of flat rollerR H And width adjustment amount delta of flat rollerHInitial width of rolled pieceW 0 Initial thickness of rolled pieceH 0 Rolling speedV 0 For the influence factors, a control variable method is adopted to carry out experimental condition arrangement, namely, under the condition that other influence factors are not changed, an experiment under different levels of a certain influence factor is set, so that for each influence factor, other influence factors are the same, but the influence factor is in the experimental condition of different levels.
Finite element simulation is carried out on each set experimental condition to obtain key parameters of head and tail defects under each experimental condition, the head and tail defects in the invention refer to the head and tail defects existing in the length direction from the overlooking angle, and the head and tail defects after finite element simulation are shown in figure 2.
The critical parameters of the head and tail defects comprise a head deformation starting point
Peak of head deformation
Peak position of head deformation
Head edge length
Starting point of tail deformation
Tail deformation peak
And the width of the slab after vertical-flat rolling
The meaning and location of each key parameter is shown in fig. 3.
And 3, step 3: fitting key parameters of head and tail defects and predicting shapes:
and (3) analyzing and acquiring the influence rules of the different influence factors on the key parameters of the head and tail defects according to the simulation results of the key parameters of the head and tail defects under the influence factors of different levels obtained in the step (2). Fitting a functional relation formula which takes the influence factors as independent variables (input variables) and takes key parameters of each head and tail defect as dependent variables (output variables) through origin and other platforms; the functional relation may be fitted as follows:
the functional expression of the key parameters of the head defect is as follows:
the function expression of the key parameters of the tail defect is as follows:
the width of the slab after neutral-flat rolling is the width of the slab after rolling at the head and the width of the slab after rolling at the tail:
whereinn=1 to 7a n 、b n 、c n 、d n 、e n 、f n 、g n Are the coefficients to be fitted. With vertical roll diameterR E For example, because of the arrangement of the control variables for the simulation experimental conditions, there is a vertical roll width adjustment ΔEDiameter of flat rollerR H And width adjustment amount delta of flat rollerHInitial width of rolled pieceW 0 Initial thickness of rolled pieceH 0 Rolling speedV 0 Other influencing factors and other factors are not changed but onlyR E Under the condition of change, finite element simulation results of key parameters of each head and tail defect can be obtained, and therefore, the function relation in the functional relation can be calculated through fitting of the simulation resultsb 1 ~b 7 . Thus can respectively calculatea n 、b n 、c n 、d n 、e n 、f n 、g n And obtaining the functional relation by waiting for each coefficient to be fitted.
Thus, for a hot continuous rough rolling vertical-horizontal rolling process to be predicted, the roll diameter of the vertical rollR E Width regulating delta of vertical rollerEDiameter of flat rollerR H Width regulating quantity delta of flat rollerHInitial width of rolled pieceW 0 Initial thickness of rolled pieceH 0 Rolling speedDegree of rotationV 0 The influence factors are determined, the predicted key parameters of the head and tail defects can be obtained by substituting the influence factors to be predicted in the hot continuous rolling rough rolling vertical-horizontal rolling process into the functional relation in the step 3, and a prediction curve of the head defect shape of the rolled piece can be fitted according to the predicted key parameters of the head and tail defectsH 1 (x) And prediction curve of tail defect shapeH 2 (x) And finishing the prediction of the shapes of the head and tail defects.
The prediction curves of the head defect shape and the tail defect shape of the rolled piece can be fitted according to the following method:
on the horizontal plane of rolled piece, as shown in fig. 3, with rolled piece head center as the origin, the width direction is the x-axis, divide into three regions with rolled piece head, specifically as follows:
in the region I, the first and second regions,
；
in the area II, the first and second zones,
；
in the third area, the first area and the second area,
；
fitting the shape of the head defect by using key parameters of the head of the rolled piece, wherein the area I represents an undeformed area in the middle of the head of the rolled piece, the areas II and III are deformation areas of the rolled piece, the area II adopts a cubic polynomial, the area III adopts a quadratic polynomial to fit, and a prediction curve of the shape of the head defect of the rolled piece is obtained
(ii) a Wherein the fitting of the head II region is performed using the axis (below)
0) and (
，
) The fitting of the head III region is performed under four conditions of two coordinate points and 0 derivative of the cubic polynomial curve at the two coordinate points by using the equation
，
) And (a)
，
) Two coordinate points and at
，
) The second order curve derivative is performed for three conditions of 0.
Similarly, on the horizontal plane of the rolled piece, as shown in fig. 3, the rolled piece tail is divided into two regions by taking the rolled piece tail center as the origin and the width direction as the x axis, specifically as follows:
in the region I, the first and second regions,
；
in the area II, the first and second zones,
；
utilizing rolled piece tail key parameters to correct tail defect shapeFitting is carried out, the area I represents an area where the middle of the tail part of the rolled piece is not deformed, the area II is a rolled piece tail part deformation area, and a cubic polynomial is adopted to fit the area II to obtain a rolled piece tail part defect shape prediction curve
(ii) a The fitting of the tail II region is carried out by using the value of (in the coordinate axis) ((II))
0) and (
，
) The two coordinate points and the cubic polynomial curve derivative at the two coordinate points are all performed under four conditions of 0.
It is obvious that the prediction curve of the head defect shape hereH 1 (x) And predicted curve of tail defect shapeH 2 (x) Are only half of the predicted shape, the other half being symmetrical.
After the prediction curves of the head defect shape and the tail defect shape of the rolled piece are obtained by the method, the curves are respectively integrated to obtain the proportion of the head defect area and the tail defect area in the horizontal area of the rolled piece, and then the head defect and the tail defect of the rolled piece are evaluated in a grading manner, as shown in fig. 6, the specific method is as follows:
step 4 rolled piece head and tail defect evaluation method
Step 4.1: integral calculation of head defect area S of rolled piece 1 ：
；
Step 4.2: calculating to obtain head evaluation value
The proportion of the head defect area to the horizontal area of the rolled piece is as follows:
；
step 4.3: integral calculation of rolled piece tail defect area S 2 ：
；
Step 4.4: calculating to obtain a tail evaluation value
The proportion of the tail defect area to the horizontal area of the rolled piece is as follows:
；
step 4.5: grading the head and tail defects of the rolled piece according to the evaluation values:
if the head evaluates the value
Evaluation is first order;
if the head evaluates the value
Evaluation was secondary;
if the head evaluates the value
Evaluation was three-stage;
if the head evaluates the value
Evaluation was four-grade;
if the head evaluates the value
Evaluation was five grades;
the smaller the evaluation value, the higher the head defect evaluation level.
If the tail evaluates the value
The evaluation was first order;
if the tail evaluates the value
Evaluation was secondary;
if the tail evaluates the value
Evaluation was three-stage;
if the tail evaluates the value
Evaluation was four-grade;
if the tail evaluates the value
Evaluation was five grades;
likewise, the smaller the rating, the higher the tail defect rating.
The invention comprehensively considers the process procedures and actual equipment in the vertical-horizontal rolling process, establishes a finite element model based on field reality, sets experiment conditions by controlling a variable method to carry out finite element simulation, establishes a function expression of key points of the vertical-horizontal rolling head and tail defects, fits a shape curve of the head and tail defects of the vertical-horizontal rolling rolled piece, and provides an evaluation method of the head and tail defects of the vertical-horizontal rolling rolled piece according to the shape curve; the defects of the head and the tail of the rolled piece after vertical-horizontal rolling are accurately predicted through numerical simulation and function fitting, and the problem that the head and the tail of the rolled piece are difficult to determine in the production process is solved; meanwhile, an evaluation method of head and tail defects is provided. The invention can provide guidance for the subsequent shearing process and reduce the cutting loss rate.
Drawings
FIG. 1 is a flow chart of rolled piece end-to-end defect prediction in accordance with an embodiment of the present invention;
FIG. 2 is a schematic diagram of finite element simulation of head and tail defects (top view) in the present invention;
FIG. 3 is a diagram for dividing the shapes of defects at the head and the tail of a rolled piece in the invention;
FIG. 4 is a diagram of a finite element model in the step of establishing a finite element model according to the present invention;
FIG. 5 is a graph showing the verification of the function curve according to the present invention;
FIG. 6 is a flow chart of the evaluation of the head and tail defect levels of the rolled piece in the invention.
Detailed Description
The following description will be made of an embodiment of the present invention with reference to the actual situation of a production site of a certain plant, and the data of the actual production process is used to compare with the defect shape curve predicted by the method of the present invention.
Step 1: creation of finite element model
Step 1.1: on-site data collection
Collecting equipment data and rolled piece data in a production field to obtain data of a roller and a rolled piece, wherein the roller diameter of a vertical roller ranges from 800mm to 1100mm, the width adjustment amount of the vertical roller ranges from 10mm to 40mm, the roller diameter of a flat roller ranges from 1100mm to 1400mm, the width adjustment amount of the flat roller ranges from 25mm to 100mm, the initial width of the rolled piece ranges from 1100mm to 1400mm, the initial thickness of the rolled piece ranges from 210mm to 240mm, the initial length of the rolled piece ranges from 1000mm, and the rolling speed ranges from 1m/s to 2.5m/s. The temperature of a rolled piece is 1050 ℃, and the temperature of a hammer head is 25 ℃;
step 1.2: building finite element model
Establishing a finite element model by using ANSYS finite element software, wherein the model comprises a rolled piece, a vertical roll and a flat roll, establishing a rolled piece vertical-flat roll rolling process, and establishing a width direction 1/2 model for saving calculation time; the rolled piece is an elastic-plastic finite element model, the vertical roll and the flat roll are rigid bodies, and meanwhile, in order to save calculation time, the vertical roll and the flat roll adopt hollow rolls. When the grids are divided, the number of grids after division is 196768 and the number of grids after division is 7440 using the SOLID164 unit, taking a rolled piece with the width multiplied by the thickness multiplied by the length =1200mm multiplied by 220mm multiplied by 1000mm as an example, and after the grids are divided by a flat roller with the roller diameter of 1200mm, the number of grids is 41899. The finite element model of the vertical-flat rolling is shown in FIG. 4;
the contact between the rolled piece and the vertical roll and the contact between the rolled piece and the flat roll are surface-to-surface contact, the dynamic friction factor is 0.26, and the static friction factor is 0.3; a symmetry plane is provided in the width direction. The material model of the rolled piece is an isotropic hardening model; the material parameters of the rolled piece and the rolls are shown in table 1, and the yield strength and the tangent modulus are not set as the vertical roll and the flat roll are set as rigid bodies.
TABLE 1 rolled stock and roll Material parameters
| Density (kg/m) 3 ) | Poisson ratio | Young's modulus (Gpa) | Yield strength (MPa) | Tangent modulus (MPa) | |
| Rolled piece | 7850 | 0.3 | 120 | 115 | 100 |
| Vertical roller | 7850 | 0.3 | 210 | ||
| Flat roll | 7850 | 0.3 | 210 |
Step 2: finite element simulation analysis
In the invention, the value ranges of the variables are as follows: diameter of vertical roll
:800mm to 1100mm, and adjusting width by using vertical roll
:10mm to 40mm, flat roll diameter
:1100mm to 1400mm, and flat roller width adjustment amount
: 25mm to 100mm and width of rolled piece
:1100mm to 1400mm, and the thickness of a rolled piece
:210mm to 240mm rolling speed
:1m/s to 2.5m/s. In order to efficiently and accurately analyze the influence on the head and tail defects of the rolled piece, a controlled variable method is adopted for research, and the influence rule of the controlled variable method on the head and tail defects is analyzed by changing the size of a variable, as shown in table 2.
TABLE 2 Experimental conditions for controlled variable method scheduling
| Factors of the fact | Diameter of vertical roll | Width adjustment of vertical roll | Diameter of flat roll | Width adjustment of flat roll | Width of rolled piece | Thickness of rolled piece | Rolling speed |
| 1 | 800 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 2 | 850 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 3 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 4 | 950 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 5 | 1000 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 6 | 1050 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 7 | 1100 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 8 | 900 | 10 | 1200 | 75 | 1200 | 220 | 2 |
| 9 | 900 | 15 | 1200 | 75 | 1200 | 220 | 2 |
| 10 | 900 | 20 | 1200 | 75 | 1200 | 220 | 2 |
| 11 | 900 | 25 | 1200 | 75 | 1200 | 220 | 2 |
| 12 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 13 | 900 | 35 | 1200 | 75 | 1200 | 220 | 2 |
| 14 | 900 | 40 | 1200 | 75 | 1200 | 220 | 2 |
| 15 | 900 | 30 | 1100 | 75 | 1200 | 220 | 2 |
| 16 | 900 | 30 | 1150 | 75 | 1200 | 220 | 2 |
| 17 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 18 | 900 | 30 | 1250 | 75 | 1200 | 220 | 2 |
| 19 | 900 | 30 | 1300 | 75 | 1200 | 220 | 2 |
| 20 | 900 | 30 | 1350 | 75 | 1200 | 220 | 2 |
| 21 | 900 | 30 | 1400 | 75 | 1200 | 220 | 2 |
| 22 | 900 | 30 | 1200 | 25 | 1200 | 220 | 2 |
| 23 | 900 | 30 | 1200 | 37.5 | 1200 | 220 | 2 |
| 24 | 900 | 30 | 1200 | 50 | 1200 | 220 | 2 |
| 25 | 900 | 30 | 1200 | 62.5 | 1200 | 220 | 2 |
| 26 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 27 | 900 | 30 | 1200 | 87.5 | 1200 | 220 | 2 |
| 28 | 900 | 30 | 1200 | 100 | 1200 | 220 | 2 |
| 29 | 900 | 30 | 1200 | 75 | 1100 | 220 | 2 |
| 30 | 900 | 30 | 1200 | 75 | 1150 | 220 | 2 |
| 31 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 32 | 900 | 30 | 1200 | 75 | 1250 | 220 | 2 |
| 33 | 900 | 30 | 1200 | 75 | 1300 | 220 | 2 |
| 34 | 900 | 30 | 1200 | 75 | 1350 | 220 | 2 |
| 35 | 900 | 30 | 1200 | 75 | 1400 | 220 | 2 |
| 36 | 900 | 30 | 1200 | 75 | 1200 | 210 | 2 |
| 37 | 900 | 30 | 1200 | 75 | 1200 | 215 | 2 |
| 38 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 39 | 900 | 30 | 1200 | 75 | 1200 | 225 | 2 |
| 40 | 900 | 30 | 1200 | 75 | 1200 | 230 | 2 |
| 41 | 900 | 30 | 1200 | 75 | 1200 | 235 | 2 |
| 42 | 900 | 30 | 1200 | 75 | 1200 | 240 | 2 |
| 43 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 44 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 45 | 900 | 30 | 1200 | 75 | 1200 | 220 | 1.25 |
| 46 | 900 | 30 | 1200 | 75 | 1200 | 220 | 1.5 |
| 47 | 900 | 30 | 1200 | 75 | 1200 | 220 | 1.75 |
| 48 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2 |
| 49 | 900 | 30 | 1200 | 75 | 1200 | 220 | 2.25 |
Analyzing the influence trend of a group of factors as an example, and analyzing the variation trend of the head and tail defects of the rolled piece under different vertical roll width adjustment quantities. When the width adjustment amount of the vertical roller is increased from 10mm to 40mm, metal deformation gradually permeates into a rolled piece, the deformation peak of the head of the rolled piece is increased to 46.33mm from 19.72mm, and the deformation peak of the tail of the rolled piece is increased to 41.5mm from 18.41 mm. The width adjustment amount of the vertical roll has great influence on the head and tail defects of the rolled piece.
And 3, step 3: fitting key parameters of head and tail defects and predicting shapes:
and (3) obtaining the shapes of the head and tail defects and key parameters of the head and tail defects of the rolled piece under different experimental conditions through numerical simulation results under the experimental conditions in the table 2, analyzing the influence trend of the key parameters of the head and tail defects under different influence factors, and fitting into a functional relation.
Common vertical roll diameter
Width regulating quantity of vertical roller
Diameter of flat roller
Width regulating quantity of flat roller
Initial width of rolled piece
Initial thickness of rolled piece
Rolling speed
The seven influencing factors are used as independent variables of the functional relation, namely input variables. The output variables (dependent variables) are the key parameters of the head and tail defects respectively. The head defect key parameters are four: starting point of head deformation
Peak of head deformation
Position of peak of head deformation
Head edge length
(ii) a Two key parameters of the tail defect are as follows: starting point of tail deformation
Peak of tail deformation
(ii) a Head and tail common width key parameters: width of slab after vertical-flat rolling
。
The function expression of the key parameters of the head defect is as follows:
the function expression of the key parameters of the tail defect is as follows:
width of the slab after neutral-flat rolling
The head-to-tail widths are the same, using the same equation, as follows:
substituting levenberg-Marquardt optimization algorithm into input variables (seven influence factors) in numerical simulation results under various experimental conditions in the table 2 respectively, and performing fitting calculation on the functional relation to obtain a function coefficient:
a n 、b n 、c n 、d n 、e n 、f n 、g n （n=1,2,3,4,5,6,7）。
step 3.2: for example, a slab having an initial dimension width × thickness × length =1200mm × 220mm × 1000mm is predicted as a head defect shape and a tail defect shape under conditions of a vertical roll width adjustment amount of 30mm, a vertical roll diameter of 900mm, a flat roll diameter of 1200mm, a flat roll width adjustment amount of 75mm, and a rolling speed of 1.6 m/s. By utilizing the function, firstly fitting the head defect shape of the rolled piece, and dividing the head of the rolled piece into three areas according to the actual head defect shape of the rolled piece and a finite element simulation result, wherein the functions are as follows:
in the region I, the crystal is formed by a crystal growing method,
；
in the area II, the first and second zones,
；
in the third area, the first area and the second area,
；
the head defect shape is fitted by using key parameters of the head of the rolled piece, the I area represents an area where the center of the head of the rolled piece is not deformed, the II area and the III area are deformation areas of the rolled piece, the II area adopts a cubic polynomial, and the III area adopts a quadratic polynomial to fit. Obtaining a prediction curve of the shape of the head defect of the rolled piece
。
Step 3.3: predicting the shape of the defect at the tail part of the rolled piece, and dividing the tail part of the rolled piece into two areas according to an actual production result and a simulation result, wherein the two areas are as follows:
in the region I, the first and second regions,
；
in the area II, the first and second zones,
；
fitting the shape of the tail defect by using key parameters of the tail of the rolled piece, wherein the area I represents an area where the center of the tail of the rolled piece is not deformed, and the area II is a deformation area of the tail of the rolled piece and is fitted by using a cubic polynomial to obtain a prediction curve of the shape of the tail defect of the rolled piece
。
The fitted curve is compared with the shape (half) of the rolled piece actually rolled under the predicted conditions, and the result is shown in fig. 5. It can be seen that the fitted curve fits well with the results of the actual rolling.
And 4, step 4: evaluation of head and tail defects of rolled piece
Step 4.1: calculating the head defect area S of the rolled piece 1 (integral):
。
step 4.2: calculating to obtain head evaluation value
The proportion of the head defect area to the horizontal area of the rolled piece is used,
wherein the content of the first and second substances,W 0 andL 0 respectively, the initial width and the initial length of the rolled piece.
Step 4.3: calculating the defect area S of the tail part of the rolled piece 2 (integration):
step 4.4: calculating to obtain a tail evaluation value
The proportion of the tail defect area to the horizontal area of the rolled piece is used,
step 4.5: and (3) grading the head and tail defects of the rolled piece according to the evaluation value:
head evaluation value
Evaluation, etcThe level is three;
tail evaluation value
The evaluation grade was two-grade.
Claims (6)
1. A method for predicting head and tail defects of a rolled piece manufactured by vertical-horizontal rolling in a hot continuous rolling rough rolling process is characterized by comprising the following steps:
step 1: creation of finite element model
Step 1.1: on-site data collection
Acquiring equipment data and rolled piece data of a production field to obtain field data of a roller and a rolled piece, wherein the field data comprises a vertical roller diameter range, a vertical roller width adjusting range, a flat roller diameter range, a rolled piece initial width range, a rolled piece initial thickness range and a rolled piece initial length L 0 And the rolling speed range;
step 1.2: building finite element model
Establishing a vertical-horizontal rolling finite element model in the rough rolling process by using finite element software; during modeling, a 1/2 model is adopted, the vertical roll and the flat roll are set as rigid bodies, and the rolled piece is set as an elastic plastic body; setting roll and product material properties, including: poisson ratio, young modulus, density, yield strength and tangent modulus, wherein the rolled piece material model adopts an isotropic hardening model; meshing the model by using a finite element software meshing tool; performing contact setting, wherein the contact type is automatic surface-surface contact, and the contact setting objects are a vertical roll, a rolled piece, a flat roll and the rolled piece respectively; carrying out boundary constraint setting, and setting a width-direction boundary as a symmetric boundary; applying load, setting initial speed in the length direction of a rolled piece, and setting angular speed of a vertical roll and a flat roll;
step 2: finite element simulation analysis:
with vertical roll diameter R E Width adjustment quantity delta E of vertical roll and roll diameter R of flat roll H Flat roll width adjustment quantity delta H and initial width W of rolled piece 0 Initial thickness H of rolled piece 0 Rolling speed V 0 For influencing factors, experimental conditions are carried out by adopting a controlled variable methodArranging, carrying out finite element simulation on each experimental condition to obtain key parameters of head and tail defects under each experimental condition, wherein the key parameters of the head and tail defects comprise a head deformation starting point
Peak of head deformation
Peak position of head deformation
Head edge length
Starting point of tail deformation
Peak of tail deformation
Width W of slab after vertical-flat rolling 1 ；
And 3, step 3: fitting key parameters of head and tail defects and predicting shapes:
fitting a functional relation with the influence factors as independent variables and each head-tail defect key parameter as dependent variables according to the simulation results of the head-tail defect key parameters under the influence factors of different levels obtained in the step 2;
substituting the predicted influence factors of the hot continuous rolling rough rolling vertical-horizontal rolling process into the functional relation to obtain predicted head and tail defect key parameters, and fitting a prediction curve H of the head defect shape of the rolled piece according to the predicted head and tail defect key parameters 1 (x) And prediction curve H of tail defect shape 2 (x)。
2. The method for predicting the head-to-tail defects of a rolled piece rolled in the vertical-horizontal rolling process of the hot continuous rolling rough rolling process according to claim 1, wherein the meshing is implemented by hexahedral meshes.
3. The method for predicting the head and tail defects of a vertically-horizontally rolled product during the hot continuous rough rolling process as claimed in claim 1, wherein the fitting of the functional relation in the step 3 is according to the following expression:
the functional expression of the key parameters of the head defect is as follows:
the function expression of the key parameters of the tail defect is as follows:
width of slab after vertical-flat rolling:
wherein n = 1-7 a n 、b n 、c n 、d n 、e n 、f n 、g n Are the coefficients to be fitted.
4. The method for predicting the head and tail defects of a rolled piece rolled in a hot continuous rough rolling process in a vertical-horizontal rolling manner according to claim 1, wherein the prediction curves of the head defect shape and the tail defect shape of the rolled piece are fitted according to the following method:
use rolled piece head center as the original point, width direction is the x axle, divide into three regions with the rolled piece head, specifically as follows:
in the region I, the crystal is formed by a crystal growing method,
in the area II, the first and second zones,
a zone III of the reaction zone,
wherein W 1 Is half of the width of the rolled piece after rolling;
fitting the shape of the head defect by using key parameters of the head of the rolled piece, wherein the area I represents an undeformed area in the middle of the head of the rolled piece, the areas II and III are deformation areas of the rolled piece, the area II adopts a cubic polynomial, the area III adopts a quadratic polynomial to fit, and a prediction curve H of the shape of the head defect of the rolled piece is obtained 1 (x)；
Use rolled piece afterbody center as the original point, width direction is the x axle, divide into two regions with the rolled piece afterbody, specifically as follows:
in the region I, the first and second regions,
in the area II, the first and second zones,
fitting the shape of the tail defect by using key parameters of the tail of the rolled piece, wherein the area I represents an undeformed area in the middle of the tail of the rolled piece, the area II is a deformed area of the tail of the rolled piece, and fitting the area II by using a cubic polynomial to obtain a prediction curve H of the shape of the tail defect of the rolled piece 2 (x)；
5. The method for predicting the head and tail defects of the vertical-horizontal rolled product in the hot continuous rolling rough rolling process according to claim 1, wherein the method for evaluating the head and tail defects comprises the following steps:
step 4 evaluation method for head and tail defects of rolled piece
Step 4.1: integral calculation of head defect area S of rolled piece 1 ：
Step 4.2: calculating to obtain a head evaluation value w h The proportion of the head defect area to the horizontal area of the rolled piece is as follows:
step 4.3: integral calculation of rolled piece tail defect area S 2 ：
Step 4.4: calculating to obtain a tail evaluation value w t The proportion of the tail defect area to the horizontal area of the rolled piece is as follows:
step 4.5: according to head evaluation value w h And tail evaluation value w t And evaluating the defects of the head and the tail of the rolled piece manufactured by vertical-horizontal rolling in the hot continuous rolling rough rolling process.
6. The method for predicting the head and tail defects of the rolled piece produced by vertical-horizontal rolling in the hot continuous rolling rough rolling process according to claim 5, wherein in the step 4.5, the head and tail defects of the rolled piece are graded according to evaluation values:
if the head evaluation value 0 < w h 0.25% or less, and evaluated as first grade;
if the head evaluation value is 0.25% < w h 0.5% or less, and evaluated as second grade;
if the head evaluation value is 0.5% < w h Less than or equal to 0.75 percent and evaluated as three grades;
if the head evaluation value is 0.75% < w h 1% or less, and evaluated as four grades;
if the head evaluation value 1% < w h Evaluation was five grades;
if the tail evaluation value is 0 < w t 0.25% or less, and evaluated as first grade;
if the tail evaluation value is 0.25% < w t 0.5% or less, and evaluated as second grade;
if the tail evaluation value is 0.5% < w t Less than or equal to 0.75 percent and evaluated as three grades;
if the tail evaluation value is 0.75% < w t 1% or less, and evaluated as four grades;
if the tail evaluation value is 1% < w t The evaluation was five grades.
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