CN102451838A - Method for overcoming camber defect in hot rolling process of steel plate - Google Patents
Method for overcoming camber defect in hot rolling process of steel plate Download PDFInfo
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Abstract
The invention discloses a method for overcoming a camber defect in the hot rolling process of a steel plate, which relates to a method for processing a rolled piece and is used for solving the problems that the defect is not controlled basically and the equipment is required to be optimized in the prior art. In the method, rolling schedules are designed respectively in a forming rolling process, a widening rolling process and a fine rolling process specific to different characteristics of three phases of the hot rolling process of the steel plate on the basis of a stably-rolled working roll flexure condition, the stably-rolled working roll flexure is taken as a constraint condition, the centering of a working roll flexure reinforcing rolled piece is enhanced, and the problem of deviation of the rolling central line of the rolled piece is reduced and even eliminated, so that the aim of overcoming the camber defect is fulfilled, the plate shape of a product is considered simultaneously, and a hot-rolled steel plate of which the size and shape meet practical requirements are finally obtained. Due to the adoption of the method, the conventional mode of adjusting working roll inclination or optimizing the equipment structure based on defect detection is changed, the camber defect is controlled radically, and equipment refitting is not required.
Description
Technical field
The present invention relates to the rolled piece method for processing, be meant the method for eliminating the camber defective in a kind of course of hot rolling especially.
Background technology
The camber defective is the FAQs that hot rolling is produced, and not only can reduce lumber recovery because of cutting to decrease to increase, and also can influence the efficient of follow-up cutting operation, when serious in addition the flipper guide and the frame that can take place to cause because of the heap steel damage.For four-high reversing mill, the reason of formation mainly is present in the following aspects: the reason of milling train, like milling train both sides stiffness difference; The reason of blank is like wedge shape, the width temperature difference of original blank; The reason of flipper guide is like flipper guide alignment deviation etc.In essence, be the initial deviation that distortion exists of depressing of rolled piece both sides, can be along with the rolling corresponding increase of carrying out, the departure degree of rolling centerline also sharply increases, and finally causes the camber of rolled piece.
Related patent U.S. Patent No. can be divided into following several types at present.
One, carries out the related patent U.S. Patent No. of camber control based on defects detection
Patent CN101182984 has proposed a kind of hot rolling slab camber and sideslip on-line detection method; This method is according to peripheral width dimensions of heating furnace and production width of plate slab size; Through heating furnace entrance and exit place slab is measured and is contrasted apart from the lateral separation of fixed point; Obtain the sickle curve of plate blank curve map, to reach the purpose of sickle curve of plate blank and shape thereof being carried out directviewing description; Patent CN101614529 has invented a kind of method of on-line continuous monitoring appearance of continuous casting sheet billet; The both sides of conticaster air cooling section roller-way with above the precision distance measurement appearance is set; Measure the distance of strand to rangefinder; Calculate strand position and shape through professional software then, confirm the camber of its generation and the amount of wedge shape, draw the casting blank shape graphics; Can be production control reliable indication is provided, with sheet billet thickness direction wedge shape and the length direction camber that prevents effectively possibly occur in the production process; In the flat rolling method and apparatus of patent US20090178457A1 invention, increase pinch roll, and eliminate camber according to detected both sides roll-force deviation adjustment both sides roll gap at the milling train outlet side; Patent US4255954A has proposed a kind of equipment of controlled rolling process plate belt profile; Promptly install several to pinch roll at the milling train outlet side; Detect the angle position of rolled piece tension force and pinch roll, working roll data is in view of the above controlled the strip profile, eliminates camber with this; In the setting that patent US7293440B2 proposes or the method for controlled rolling process light plate wedge shape; Measure the plate width direction thickness distribution through the wedge shape measuring instrument being installed in the blooming mill outlet; Calculate based on measured value; Utilize the rolled piece wedge shape that the influence coefficient of roll gap is confirmed the wedge shape of setting of roll gap tilt quantity or controlled rolling process light plate, thereby eliminate the camber defective; In the method and apparatus of the rolled metal material of patent EP1607149B1 invention, according to the roll-force bias adjustment roll gap inclination control camber of transmission side and fore side.
More than these patents based on direction, the degree of the camber that has occurred; Roll gap artificial or that automatically regulate the milling train both sides is tilted in follow-up passage compensation rolled piece thickness of two sides difference and reaches the purpose of improving this kind defective; But all need online camber to be measured and judge more accurately, though these methods be suitable in the hot-rolled steel plate field because milling train inclination adjustable extent is limited; For the normal thin specification rolled piece of sending out of camber; When preceding passage camber was serious, the method will be powerless, even play reaction.The method of this type belongs to the pattern that the defective that has produced is weakened and even eliminates, and does not get on to control generation of defects from root.
Two, based on device structure design, process optimization to eliminate the related patent U.S. Patent No. of camber
Patent CN101224471 has invented a kind of control method of roughing intermediate blank camber; Adopt the control of Position Control and pressure to combine; Control flipper guide opening degree; Intermediate blank to the roughing mill entrance and exit retrains flexural deformation in the horizontal direction, realizes reducing the intermediate blank camber, prevents the heavy wear that flipper guide and intermediate blank Long contact time produce simultaneously; Patent CN101259482 provides the rolling mill practice of the rolling 6mm steel plate of a kind of heavy and medium plate mill; The rolling mill practice of the rolling 6mm steel plate of a kind of heavy and medium plate mill; It is characterized in that roll-force adaptation coefficient between tapping temperature, sotck thinkness, rolling pass, AGC, roll-force, passage to blank, convexity, rollgang linear velocity have been carried out respective settings with operation roll of mill linear velocity coupling relatively, solved the sheet material appearance often in the test of 6mm plate is rolling of existing heavy and medium plate mill wave, the song that wafts, camber, scrape frame, roll problems such as useless; Patent CN200939463 discloses the floating milling train of a kind of magnetic; Adopt the repulsive force of the high-intensity magnetic field that electromagnet produced of paired shielding; To backing roll and upper working rolls and lower working rolls evenly press down the application of force up and down; Make the whole stress equalization of the body of roll of working roll, thus can solve effectively the rolling process central roll that adopts the two ends mode of pressing down to exist to the body of roll experience the power inequality, deformation takes place, cause occurring in the operation of rolling problem of bad phenomenon such as camber, limit wave, middle wave, the shape of wafing, skew and broken belt; Patent US2029751A has proposed a kind of rolling mill structure, eliminates camber through a kind of drum tension device; Patent US6318141B1 has proposed a kind of roller straightener that is used for the metal plate and belt aligning.New design transformed or proposed to these methods need to hot rolling mill and relevant device.
Summary of the invention
The objective of the invention is in order to overcome the problem that prior art exists, provide a kind of and get on to control generation of defects and need not transform a kind of method of eliminating hot-rolled steel plate process camber defective of milling equipment from root.
The objective of the invention is to realize through following technical scheme:
A kind of method of eliminating hot-rolled steel plate process camber defective is the method that adopts different elimination hot-rolled steel plate process camber defectives to three rolling processes of shaping rolling process, broadening rolling process, finish rolling rolling process in the hot-rolled steel plate process respectively:
S1, the shaping rolling process;
S2, the broadening rolling process;
The method of in S1, two rolling processes of S2, eliminating hot-rolled steel plate process camber defective is: all adopt the working roll flexing conditions based on stable rolling separately; Add and have much the negative convexity of carrying roll gap; Make rolled piece centering through increasing deflection; With the best deflection of working roll as the constraints distribution load, increase roll-force, reduce positive bending roller force, accomplish rolling with minimum passage;
S3, the finish rolling rolling process, the method for eliminating hot-rolled steel plate process camber defective in this rolling process is: increase along with rolled piece extends; Reduced thickness, the design critical thickness, rolled piece is still pressed the working roll flexing conditions distribution load of stable rolling more than critical thickness; When rolled piece arrival critical thickness is following, serve as the main sub-distribution of carrying out with control panel shape, auxiliary with the working roll wing drop; As constraint means, slow down the speed of camber expansion.
Eliminate the flow process of camber defective in the said S1 shaping rolling process:
S11 confirms the rolling process restrictive condition;
S12 confirms this rolling process target thickness;
S13, the best deflection constraints of evaluation work roller;
S14 presses the best deflection constraints of working roll and calculates this rolling process road number of times and each reduction in pass, and the shaping rolling process finishes.
Eliminate the flow process of camber defective in the said S2 broadening rolling process:
S21 confirms the rolling process restrictive condition;
S22 confirms this rolling process target thickness;
S23, the best deflection constraints of evaluation work roller;
S24 presses the best deflection constraints of working roll and calculates this rolling process road number of times and each reduction in pass, and the shaping rolling process finishes.
The best deflection constraints of said evaluation work roller and press the step of working roll deflection constraints this rolling process road number of times of calculating and each reduction in pass following:
The 1st step, when the working roll body of roll is cylindrical, the roll shape convexity is ± 0 o'clock, rolled piece causes the thickness difference Δ of rolled piece both sides by the distance of rolling centerline skew a
1, calculate Δ
1:
Wherein, P is a draught pressure, is given value, and scope is 0-75000kN;
B is the rolled piece width, is given value, and scope is 600mm-2800mm;
A is the distance of rolled piece by rolling off-centring, and by measuring, scope is 0-1100mm;
A is two distances between the housing screw axis, is given value, and unit is mm;
K is a mill stiffness, is given value, and span is 5000-10000kN/mm;
During the 2nd step, working roll deflection produced under the roll-force effect negative convexity roll forming, the rolled piece side-play amount is that the drafts of a one side increases, and produces the thickness difference Δ
2, calculate Δ
2:
Wherein, y
PWorking roller bending deflection value for roll-force produces is given value, and span is 0-1mm;
y
tBe hot convex value, be given value, span is 0-0.5mm;
W is original roll forming convex value, is given value, and span is-0.5-0.5mm.
These two kinds effects that form formula (1), (2) are opposite, as long as satisfy following formula (3), rolled piece produces and is stable at rolling centerline trend, make skew avoid enlarging and developing towards the direction of dwindling, and obtain thus, when original roller type one timing, by Δ
2=Δ
1Obtain formula (4), the working roll minimum bend deflection value that calculation stability is rolling:
Δ
1≤Δ
2 (3)
The 3rd step is calculated the influence to the working roll deflection of the bending roller force be applied on the working roll two end axles bearing, and according to the simply supported beam bending die, the working roll distortion that bending roller force produces can be solved by formula (5), and computed range is the working roller bending deflection value y at x place
B:
Wherein, c=4/ (3 π E
BD
B 4);
β＝3L
2-B
2；
α＝4(D
B/d
B)
4；
e＝(L-B)/2；
E
BBe the working roll elastic modelling quantity, be given value, value is about 215600MPa;
y
BBe the working roll amount of deflection of distance for the x place, unit is mm;
D
BBe work roll diameter, unit is mm;
d
BBe the working roll bearing block diameter, unit is mm;
F
BBe bending roller force, span is that 1800-2500 is kN;
X is that the optional position is apart from the distance of the bending roller force point of application on the working roll length direction, and span is 0-2800mm;
L is a working roll length, and unit is mm;
U is 0-2010mm for the distance of the bending roller force point of application to the working roll top, span;
B is the rolled piece width, and unit is mm;
The deflection that working roll deflection that positive bending roller force causes and roll-force produce is in the opposite direction, and composite type (4), formula (5) have drawn through increasing the formula (6) that deflection makes the best deflection constraints of working roll of rolled piece centering:
Wherein, y is the minimum deflection value of roll-force, bending roller force acting in conjunction bottom working roll, and unit is mm;
The 4th step is distributed drafts by the working roll flexing conditions that satisfies formula (6) requirement, increases roll-force, reduces bending roller force; Guarantee the working roll deflection degree of each passage, add and have much the negative convexity of carrying roll gap, guarantee the stable of rolled piece; Deduct target thickness by this rolling process original depth and be the rolling process overall reduction; Divided by the passage maximum reduction that obtains according to constraints (formula 6), can obtain the road number of times of rolling process again, and each reduction in pass accordingly.
Eliminate the flow process of camber defective in the said S3 finish rolling rolling process:
S31 confirms the rolling process restrictive condition;
S32 confirms the critical thickness that this rolling process target thickness and plate shape are controlled;
S33, the working roll flexing conditions of pressing stable rolling is calculated this rolling process road number of times and each reduction in pass with the best deflection constraints of said working roll;
S34 judges that whether passage thickness is greater than above-mentioned critical thickness;
S35, if passage thickness greater than above-mentioned critical thickness, reduction in pass remains unchanged;
S36 if passage thickness less than above-mentioned critical thickness, carries out reduction in pass optimization according to plate shape model, follows the principle of constant proportion example convexity; Reduce drafts gradually, roll-force is reduced gradually, and increase positive bending roller force; The convexity of control final products, and prevent the generation that the limit is unrestrained, flow process finishes.
Confirming of said critical thickness according to concerning that employing formula (7) is calculated between the milling train fore side of each passage exit thickness and corresponding passage and the milling train transmission side both sides rolling deviation:
Wherein, h is the critical thickness value, and unit is mm;
a
0Be correction factor, span is 0-10;
a
1, a
2, a
3Be material regression parameter, a
1, a
2, a
3Span is respectively 0-10000,0-1,0-1000.
The following beneficial effect that the present invention can reach:
The present invention is thickness 100mm-800mm to the rolled piece blank; The continuous casting billet of width 600mm-2000mm, forging stock, die casting slab ingot or electroslag slab ingot; Finished product is that target size is thickness 4mm-80mm, width 600mm-2500mm, and length is carbon steel, stainless steel, special steel or the specific alloy sheet material of 2000mm-8000mm; In the operation of rolling since the steel plate both sides depress the deviation that distortion exists can be along with the rolling corresponding increase of carrying out; The departure degree of rolling centerline also sharply increases, and finally can cause these hot rolling technology technological difficulties of camber defective, and a kind of method of eliminating this defective is provided.The present invention has changed traditional pattern based on defects detection adjustment working roll inclination or optimizing equipment structure; Can produce and the characteristics of expansion to course of hot rolling steel plate camber defective, overcome the technology controlling and process difficult point that rolled piece in the operation of rolling very easily departs from rolling centerline, not only can reduce and even eliminate the camber defective; Enhance productivity and lumber recovery; Simultaneously can take into account production board shape, meet industrial production requirement, be easy to commercial Application.In addition, in the hot rolled strip production process, the distortion deviation of depressing of rolled piece both sides very easily occurs; It is along with the rolling corresponding increase of carrying out meeting, and the departure degree of rolling centerline also can sharply increase, the appearance of the camber defective that finally can cause; This is one of difficult point of hot rolled strip production always; This method can be generalized to each hot rolled strip and produces line, and especially four roller reversible hot-rolling mills and wide and heavy plate mill produce line, and this method can well address this problem.
For further specifying above-mentioned purpose of the present invention, characteristic and effect, below will combine accompanying drawing that the present invention is elaborated.
Description of drawings
Fig. 1 is an elimination camber defective method flow diagram of the present invention;
Fig. 2 is a shaping rolling process flow chart of steps of the present invention;
Fig. 3 is a broadening rolling process flow chart of steps of the present invention;
Fig. 4 is a finish rolling rolling process flow chart of steps of the present invention;
Fig. 5 is the sketch map that is shaped, the broadening rolling process influences final camber;
The sketch map of rolled piece generative center line drift condition when Fig. 6 is the straight roll gap of working roll;
The sketch map of rolled piece generative center line drift condition when Fig. 7 bears the convexity roll gap for the working roll deflection produces;
The deflection sketch map that Fig. 8 causes for bending roller force;
Fig. 9 is the thickness critical point sketch map of finish rolling rolling process.
The specific embodiment
Accompanying drawing specific embodiments of the invention below in conjunction with embodiment is elaborated.
The invention provides a kind of method of eliminating hot-rolled steel plate process camber defective, be based on the working roll flexing conditions of stable rolling, to the different characteristics of the three phases of hot-rolled steel plate process; Rolling process, broadening rolling process, finish rolling rolling process promptly are shaped; Design rolling procedure respectively, as constraints, increase the working roll deflection and strengthen rolled piece centering with the working roll deflection of stable rolling; Alleviate even eliminate the rolling centerline skew problem of rolled piece; Thereby reach the purpose of eliminating the camber defective, take into account the plate shape of product simultaneously, finally obtain size shape and all satisfy the actual hot rolled steel plate that requires.Referring to Fig. 1, elimination camber defective method of the present invention is in the S1 of hot-rolled steel plate process shaping rolling process, S2 broadening rolling process, three rolling processes of S3 finish rolling rolling process, to carry out respectively, below the main contents:
In S1, S2 step, all adopt separately to increase the working roll deflection, strengthen the method for rolled piece centering; Promptly all adopt working roll flexing conditions separately based on stable rolling; Add and have much the negative convexity of carrying roll gap, make rolled piece centering through increasing deflection, with the best deflection of working roll as the constraints distribution load, increase roll-force, reduce positive bending roller force; Rolling with minimum passage completion, strengthen rolled piece centering through increasing the working roll deflection.
In the S3 step,, rolled piece increases reduced thickness along with extending; In this step, design critical thickness, rolled piece is pressed the working roll flexing conditions distribution load of stable rolling more than critical thickness, promptly still presses the best deflection degree distribution load of working roll; When rolled piece arrival critical thickness is following, serve as the main sub-distribution of carrying out with control panel shape, auxiliary with the working roll wing drop; As constraint means, slow down the speed of camber expansion.
Be described in detail in the method for eliminating the camber defective in above-mentioned three rolling process steps below:
S1, shaping rolling process step, referring to Fig. 2, eliminate the flow process of camber defective in this step:
S11 confirms rolling process restrictive condition (comprising roll-force, roll torque, bending roller force, drafts, the isoparametric usable range of mill speed);
S12 confirms this rolling process target thickness;
S13, the best deflection constraints of evaluation work roller;
S14 presses the best deflection constraints of working roll and calculates this rolling process road number of times and each reduction in pass, and the shaping rolling process finishes.
S2, broadening rolling process step, referring to Fig. 3, eliminate the flow process of camber defective in this step:
S21 confirms rolling process restrictive condition (comprising roll-force, roll torque, bending roller force, drafts, the isoparametric usable range of mill speed);
S22 confirms this rolling process target thickness;
S23, the best deflection constraints of evaluation work roller;
S24 presses the best deflection constraints of working roll and calculates this rolling process road number of times and each reduction in pass, and the shaping rolling process finishes.
In shaping rolling process, broadening rolling process, all adopting separately increases the working roll deflection, strengthens the method for steel plate centering.Shaping rolling process, two stages of broadening rolling process, like Fig. 2, shown in 3,, confirm rolling restrictive condition at first according to the capacity of equipment of milling train, comprise roll-force, roll torque, bending roller force, drafts, the isoparametric scope of mill speed; Afterwards, confirm the target thickness of corresponding rolling process, and calculate the constraints of the working roll deflection that can avoid the camber defective; And calculate each reduction in pass based on this and calculate number of times.
Shaping, these two rolling processes of broadening, though be in preceding, the mid-term of the operation of rolling respectively, the camber that occur this moment produces significant impact to final products.As shown in Figure 5, among the figure, arrow R direction is a rolling direction, and dotted line S is a rolling centerline; As shown in the figure, if 1 camber takes place in the shaping rolling process, then change steel after, flipper guide is centering accurately; Rolling centerline can squint, and causes rolled piece (hot rolled steel plate) 1 to play pendulum, and the camber defective of rolled piece 1 is amplified; Broadening rolling process afterwards with it in like manner, final rolling when proceeding to last rolling process, the camber of rolled piece 1 has been difficult to control.From another point of view, in these two rolling processes, rolled piece 1 is relatively short, narrower, also more helps the correction after roll line squints.
Calculation procedure in evaluation work roller deflection constraints described in shaping, these two rolling processes of broadening is following:
Can know that by rolling principle when the working roll body of roll is cylindrical, promptly its roll shape convexity is at ± 0 o'clock,, can cause the thickness difference Δ of rolled piece 1 both sides if rolled piece 1 is as shown in Figure 6 by the distance of rolling centerline skew a
1, promptly
Wherein, P is a draught pressure, is given value, and scope is 0-75000kN;
B is the rolled piece width, is given value, and scope is 600mm-2800mm;
A is the distance of rolled piece by rolling off-centring, can be through measuring, and scope is 0-1100mm;
A is two distances between the housing screw axis, is given value, and unit is mm;
K is mill stiffness (not comprising working roll rigidity), is given value, and span is 5000-10000kN/mm.
The implication that above-mentioned each symbol is represented in the formula below is identical with the unit of employing, does not give unnecessary details.
But in the actual operation of rolling; The working roll negative convexity roll forming that deflection produced under the roll-force effect; As shown in Figure 7 (for convenient calculating merges to lower roll with the convexity of two working rolls here; And make the top roll cylindrical), making the rolled piece side-play amount is that the drafts of a one side increases, and can produce the thickness difference Δ
2, promptly
Wherein, y
PWorking roller bending deflection value for roll-force produces is given value, and span is 0-1mm;
y
tBe hot convex value, be given value, span is 0-0.5mm;
W is original roll forming convex value, is given value, and span is-0.5-0.5mm.
Because it is opposite to form these two kinds effects of formula (1), (2), as long as therefore satisfy following formula (3), making it cancel out each other or make the latter (is Δ greater than the former
2＞Δ
1), rolled piece 1 is produced be stable at rolling centerline S trend, make little chance skew avoid enlarging and developing towards the direction of dwindling, also can obtain thus, as original roller type one timing, the working roll minimum bend deflection value y of stable rolling
Pmin(by Δ
2=Δ
1The time obtain), be shown in the formula (4).
Δ
1≤Δ
2 (3)
In addition, also to consider to be applied to bending roller force on the working roll two end axles bearing to the influence of working roll deflection degree, as shown in Figure 8; According to simply supported beam bending die (simply supported beam bending die be known technology) in the industry; The working roll distortion that bending roller force produces can be solved by formula (5), because the deflection that positive bending roller force generation working roll deflection and roll-force produce is in the opposite direction, representes with negative value here; That is, distance is the working roller bending deflection value y at x place
B
Wherein, c=4/ (3 π E
BD
B 4);
β＝3L
2-B
2；
α＝4(D
B/d
B)
4；
e＝(L-B)/2；
E
BBe the working roll elastic modelling quantity, be given value, value is about 215600MPa;
y
BBe the working roll amount of deflection of distance for the x place, unit is mm;
D
BBe work roll diameter, unit is mm;
d
BBe the working roll bearing block diameter, unit is mm;
F
BBe bending roller force, span is that 1800-2500 is kN;
X is that the optional position is apart from the distance of the point of application (being the point of application of bending roller force) on the working roll length direction, and span is 0-2800mm);
L is a working roll length, and unit is mm;
U is the distance of the point of application (the bending roller force point of application) to the working roll top, and u is that roller is directly gone up the arbitrfary point, and span is 0-2010mm;
B is the rolled piece width, and unit is mm.
The deflection that working roll deflection that positive bending roller force causes and roll-force produce is in the opposite direction; The working roll deflection that comprehensive roll-force, bending roller force cause; Be formula (4), formula (5), just drawn through increasing the best deflection constraints of working roll that deflection makes rolled piece centering, shown in (6).
Wherein, y is the minimum deflection value of roll-force, bending roller force acting in conjunction bottom working roll, and unit is mm.
Therefore, in shaping rolling process, two stages of broadening rolling process, all distribute drafts by the working roll flexing conditions that satisfies formula (6) requirement; Increase roll-force, reduce bending roller force, guarantee the working roll deflection degree of each passage, add and have much the negative convexity of carrying roll gap; Guarantee the stable of rolled piece, make its problem that does not depart from rolling centerline, then; Deduct target thickness by this rolling process original depth and be the rolling process overall reduction; Divided by the passage maximum reduction that obtains according to constraints (formula 6), can obtain the road number of times of rolling process again, and each reduction in pass accordingly.
S3, finish rolling rolling process step, referring to Fig. 4, eliminate the camber defective in this step and adopt the expansion of control camber to take into account production board shape, its flow process:
S31 confirms rolling process restrictive condition (comprising roll-force, roll torque, bending roller force, the isoparametric usable range of mill speed);
S32 confirms the critical thickness (definite method of this critical thickness will be explained below) that this rolling process target thickness and plate shape are controlled;
S33 calculates this rolling process road number of times and each reduction in pass by the best deflection constraints of working roll (being formula 6);
S34 judges that whether passage thickness is greater than above-mentioned critical thickness;
S35, if passage thickness greater than above-mentioned critical thickness, reduction in pass remains unchanged;
S36 is if passage thickness less than above-mentioned critical thickness, carries out reduction in pass optimization according to plate shape model; Promptly follow the principle (principle of constant proportion example convexity be known technology) in the industry of constant proportion example convexity, reduce drafts gradually, roll-force is reduced gradually; And increase positive bending roller force; The convexity of control final products, and prevent the generation that the limit is unrestrained, flow process finishes.
In the finish rolling rolling process; Rolled piece camber expansion rate can be along with the obvious quickening that reduces of exit thickness; During last several passage before the rolling end; Be difficult to go the compensation correction through the deflection of working roll, in addition, plate shape that the more important thing is final finished also is one of important control target of production process.As shown in Figure 4, at first the same with S1, S2 step, earlier according to rolling restrictive condition and target thickness; Calculate each reduction in pass, road number of times based on the constraints of the working roll deflection that can avoid the camber defective, the critical thickness according to the control of plate shape carries out drafts optimization afterwards, when passage target thickness during greater than critical thickness; The drafts distribution remains unchanged; When passage target thickness during, drafts is optimized explanation specific as follows less than critical thickness.
Select the sub-distribution of different roads for use in the thickness critical point:
Relation between each passage exit thickness and corresponding passage OS, DS (OS is the milling train fore side, and DS is the milling train transmission side) the both sides rolling deviation, as shown in Figure 9; Both sides roll-force deviation is big more, explains that camber is serious more, and dotted line is represented the Trendline of both sides roll-force deviation with varied in thickness among the figure; The roll-force deviation of some subrepresentation OS and DS both sides, this figure will explain critical thickness is how to obtain, the unit of ordinate is kN; Abscissa is a rolled piece thickness, turns right thicker and thicker, from figure, can obviously find out reduce (near the position of reference axis) along with thickness; Both sides roll-force deviation increasing (among the figure on the position of idea rise very fast) explain that the expansion rate of camber is fast more), rolled piece camber expansion rate is along with obviously quickening after exit thickness the arrives a certain scope; Therefore in order to take into account the needs of camber expansion rate and plate shape control; Select this one of them thickness as equalization point, exit thickness is main with the control camber when critical value is above; Press the constraints of working roll deflection and distribute drafts, thereby increase the stability of rolled piece in the operation of rolling.Exit thickness serves as the main sub-distribution of carrying out with control panel shape after below the critical value.As constraint means, slow down the speed of camber expansion through the working roll wing drop this moment.
The selection of finish rolling rolling process thickness critical point (critical thickness):
The selection of thickness critical value adopts formula (7) to calculate according to concerning between each passage exit thickness and corresponding passage OS, the DS both sides rolling deviation.
Wherein, h is the critical thickness value, and unit is mm;
a
0Be correction factor, span is 0-10;
a
1, a
2, a
3Be material regression parameter, a
1, a
2, a
3Span is respectively 0-10000,0-1,0-1000.
Be embodiment to produce austenitic stainless steel 304 steel plates below, enforcement of the present invention is remarked additionally.
Used rolled piece is a continuous casting steel billet, and material composition is as shown in table 1.
(unit: wt%)
| C | Si | Mn | P | S | Cu | Cr | Ni | Mo | Ti |
| 0.022 | 0.45 | 1.37 | 0.027 | 0.001 | 0.2 | 16.26 | 10.17 | 2.08 | 0.01 |
Used rolled piece slab is of a size of: thickness 148mm, width 1301mm, length 1138mm, weight 1768kg;
Target size is: thickness 6.5mm, width 2100mm.
Start rolling temperature: 1150 ℃.
Shaping rolling process, broadening rolling process:
Through adopting heavy reduction; Do not use positive bending roller force; The roller equilibrant force 1800kN that only comes into operation increases the working roll deflection degree of each passage, adds and has much the negative convexity of carrying roll gap; Satisfy roll-force, the bending roller force constraints (formula 6) of rolled piece centering, thereby avoided rolled piece to depart from the generation of rolling centerline problem.
Concrete rolling procedure is as shown in table 2 below.
The actual rolling procedure table of table 2 shaping rolling process, broadening rolling process
Each size is the hot value of considering after the thermal expansion in the table
The finish rolling rolling process:
The thickness critical value of finish rolling rolling process is calculated according to formula 7, correction factor a
0Value is 1, material regression parameter a
1, a
2, a
3Be respectively 5591.2,0.72,646.79.
Therefore the thickness critical value is 20mm, after exit thickness is less than 20mm, is that target is carried out sub-distribution with the control template, increases bending roller force and comes the control panel convexity and eliminate the limit wave.Exit thickness is pressed working roll deflection constraints and is distributed drafts when 20mm is above, satisfies formula 6.Concrete rolling procedure is as shown in table 3 below.
The actual rolling procedure table of table 3 finish rolling rolling process
Each size is the hot value of considering after the thermal expansion in the table
Thick austenitic stainless steel 304 hot rolled steel plates of 6.29mm that the elimination hot-rolled steel plate process camber defective method that proposes according to the present invention shuts out, no camber defective, plate shape is good, has proved the validity of the elimination hot rolling camber method that the present invention proposes.
Those of ordinary skill in the art will be appreciated that; Above embodiment is used for explaining the object of the invention; And be not with opposing qualification of the present invention; As long as in essential scope of the present invention, all will drop in the scope of claim of the present invention variation, the modification of the above embodiment.
Claims (6)
1. method of eliminating hot-rolled steel plate process camber defective is characterized in that adopting respectively to three rolling processes of shaping rolling process, broadening rolling process, finish rolling rolling process in the hot-rolled steel plate process method of different elimination hot-rolled steel plate process camber defectives:
S1, the shaping rolling process;
S2, the broadening rolling process;
The method of in S1, two rolling processes of S2, eliminating hot-rolled steel plate process camber defective is: all adopt the working roll flexing conditions based on stable rolling separately; Add and have much the negative convexity of carrying roll gap; Make rolled piece centering through increasing deflection; With the best deflection of working roll as the constraints distribution load, increase roll-force, reduce positive bending roller force, accomplish rolling with minimum passage;
S3, the finish rolling rolling process, the method for eliminating hot-rolled steel plate process camber defective in this rolling process is: increase along with rolled piece extends; Reduced thickness, the design critical thickness, rolled piece is still pressed the working roll flexing conditions distribution load of stable rolling more than critical thickness; When rolled piece arrival critical thickness is following, serve as the main sub-distribution of carrying out with control panel shape, auxiliary with the working roll wing drop; As constraint means, slow down the speed of camber expansion.
2. eliminate the method for hot-rolled steel plate process camber defective according to claim 1, it is characterized in that:
Eliminate the flow process of camber defective in the said S1 shaping rolling process:
S11 confirms the rolling process restrictive condition;
S12 confirms this rolling process target thickness;
S13, the best deflection constraints of evaluation work roller;
S14 presses the best deflection constraints of working roll and calculates this rolling process road number of times and each reduction in pass, and the shaping rolling process finishes.
3. eliminate the method for hot-rolled steel plate process camber defective according to claim 1, it is characterized in that:
Eliminate the flow process of camber defective in the said S2 broadening rolling process:
S21 confirms the rolling process restrictive condition;
S22 confirms this rolling process target thickness;
S23, the best deflection constraints of evaluation work roller;
S24 presses the best deflection constraints of working roll and calculates this rolling process road number of times and each reduction in pass, and the shaping rolling process finishes.
4. like the method for claim 2 or 3 said elimination hot-rolled steel plate process camber defectives, it is characterized in that:
The best deflection constraints of said evaluation work roller and press the step of working roll deflection constraints this rolling process road number of times of calculating and each reduction in pass following:
The 1st step, when the working roll body of roll is cylindrical, the roll shape convexity is ± 0 o'clock, rolled piece causes the thickness difference Δ of rolled piece both sides by the distance of rolling centerline offset alpha
1, calculate Δ
1:
Wherein, P is a draught pressure, is given value, and scope is 0-75000kN;
B is the rolled piece width, is given value, and scope is 600mm-2800mm;
α is the distance of rolled piece by rolling off-centring, and by measuring, scope is 0-1100mm;
A is two distances between the housing screw axis, is given value, and unit is mm;
K is a mill stiffness, is given value, and span is 5000-10000kN/mm;
During the 2nd step, working roll deflection produced under the roll-force effect negative convexity roll forming, the rolled piece side-play amount is that the drafts of α one side increases, and produces the thickness difference Δ
2, calculate Δ
2:
Wherein, y
pWorking roller bending deflection value for roll-force produces is given value, and span is 0-1mm;
y
tBe hot convex value, be given value, span is 0-0.5mm;
W is original roll forming convex value, is given value, and span is-0.5-0.5mm.
These two kinds effects that form formula (1), (2) are opposite, as long as satisfy following formula (3), rolled piece produces and is stable at rolling centerline trend, make skew avoid enlarging and developing towards the direction of dwindling, and obtain thus, when original roller type one timing, by Δ
2=Δ
1Obtain formula (4), the working roll minimum bend deflection value that calculation stability is rolling:
e＝(L-B)/2 (3)
The 3rd step is calculated the influence to the working roll deflection of the bending roller force be applied on the working roll two end axles bearing, and according to the simply supported beam bending die, the working roll distortion that bending roller force produces can be solved by formula (5), and computed range is the working roller bending deflection value y at x place
B:
Wherein, c=4/ (3 π E
BD
B 4);
β＝3L
2-B
2；
α＝4(D
B/d
B)
4；
e＝(L-B)/2；
EB is the working roll elastic modelling quantity, is given value, and value is about 215600MPa;
YB is the working roll amount of deflection of distance for the x place, and unit is mm;
DB is a work roll diameter, and unit is mm;
DB is the working roll bearing block diameter, and unit is mm;
FB is a bending roller force, and span is that 1800-2500 is kN;
X is that the optional position is apart from the distance of the bending roller force point of application on the working roll length direction, and span is 0-2800mm;
L is a working roll length, and unit is mm;
U is 0-2010mm for the distance of the bending roller force point of application to the working roll top, span;
B is the rolled piece width, and unit is mm;
The deflection that working roll deflection that positive bending roller force causes and roll-force produce is in the opposite direction, and composite type (4), formula (5) have drawn through increasing the formula (6) that deflection makes the best deflection constraints of working roll of rolled piece centering:
Wherein, y is the minimum deflection value of roll-force, bending roller force acting in conjunction bottom working roll, and unit is mm;
The 4th step is distributed drafts by the working roll flexing conditions that satisfies formula (6) requirement, increases roll-force, reduces bending roller force; Guarantee the working roll deflection degree of each passage, add and have much the negative convexity of carrying roll gap, guarantee the stable of rolled piece; Deduct target thickness by this rolling process original depth and be the rolling process overall reduction; Divided by the passage maximum reduction that obtains according to constraints (formula 6), can obtain the road number of times of rolling process again, and each reduction in pass accordingly.
5. eliminate the method for hot-rolled steel plate process camber defective according to claim 1, it is characterized in that:
Eliminate the flow process of camber defective in the said S3 finish rolling rolling process:
S31 confirms the rolling process restrictive condition;
S32 confirms the critical thickness that this rolling process target thickness and plate shape are controlled;
S33, the working roll flexing conditions of pressing stable rolling is calculated this rolling process road number of times and each reduction in pass with the best deflection constraints of said working roll;
S34 judges that whether passage thickness is greater than above-mentioned critical thickness;
S35, if passage thickness greater than above-mentioned critical thickness, reduction in pass remains unchanged;
S36 if passage thickness less than above-mentioned critical thickness, carries out reduction in pass optimization according to plate shape model, follows the principle of constant proportion example convexity; Reduce drafts gradually, roll-force is reduced gradually, and increase positive bending roller force; The convexity of control final products, and prevent the generation that the limit is unrestrained, flow process finishes.
6. like the method for the said elimination hot-rolled steel plate of claim 5 process camber defective, it is characterized in that:
Confirming of said critical thickness according to concerning that employing formula (7) is calculated between the milling train fore side of each passage exit thickness and corresponding passage and the milling train transmission side both sides rolling deviation:
Wherein, h is the critical thickness value, and unit is mm;
α
0Be correction factor, span is 0-10;
α
1, α
2, α
3Be material regression parameter, α
1, α
2, α
3Span is respectively 0-10000,0-1,0-1000.
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