CN1943891A - Hot rolling strip steel convex degree control method based on smooth change rolling rule - Google Patents

Abstract

The present invention relates to method of controlling convexity degree of strip steel, and is especially method of controlling convexity degree of hot rolled strip steel based on smoothly changed rolling rule. The method of controlling convexity degree of hot rolled strip steel includes dividing the successively connected hot rolling frames into upstream rolling frames, middle rolling frames and downstream rolling frames; regulating the reduction degrees of the rolling frames during rolling the first 80-120 strip coils one coil by one coil; and maintaining the reduction degrees of the rolling frames unchanged in the subsequent rolling. The method of the present invention has smooth change in the load distribution in the rollers, simple function structure, easy regulation and precisely controlled convexity degree and straightness of the hot rolled strip steel.

Description

A kind of hot-strip convex degree control method based on the smooth change rolling procedure

Technical field

The present invention relates to a kind of method of controlling finished product hot strip steel convexity.

Background technology

Hot strip steel is in a rolling cycle of roll, because the variation of roller heat convex degree learning and wear extent, the convexity of band steel own also changes a lot.Take all factors into consideration the influence of wearing and tearing and hot convexity, actual measurement finished strip convexity can change to 20 μ m by 100 μ m in a rolling cycle.Up to now, domestic most continuous hot-rolling mill adopts the powerful curved control that the working roll mode is carried out plate shape of scurrying, though curved roll shifting control technology comparative maturity, and quilt generally acknowledges it is the effective means of control panel shape, but, be subjected to bending roller force simultaneously, particularly the restriction of roller model accuracy because there is the work dead band in the work roll bending mode of scurrying, change for above-mentioned bigger convexity, only rely on hydraulic bending roll not compensate.Because complete plat control system is by the integral system that type-roll shape-technology-four part organic combinations of control become, so can promptly seek solution from changing rolling procedure aspect the technology.

Summary of the invention

Roller system in course of hot rolling controls not enough problem for strip crown at present band steel, the invention provides a kind of method that can effectively control finished product hot-strip convexity, this method adopts, and to seamlessly transit function structure simple, easy to use, more accurate for the control of strip crown and glacing flatness.

A kind of hot-strip convex degree control method based on the smooth change rolling procedure, it is that rolling-mill housing with rolling hot strip steel is divided into upstream frame, middle reaches frame and downstream frame successively by rolling order, according to steel rolling volume number is with the volume adjustment, concrete method of adjustment is in the operation of rolling of each frame reduction ratio before 80～120 coils:

The relative reduction ratio r of downstream frame _iIncrease by volume according to formula (A):

$r_i=r_{0i}(1+a_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})...\left(A\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; a _iTime effects coefficient for the relative reduction ratio of each frame of downstream;

The maximum of the relative reduction ratio recruitment of downstream frame is controlled in 40%～50% scope of the relative reduction ratio of corresponding frame benchmark;

The relative reduction ratio r of upstream frame _iReduce by volume according to formula (B):

$r_i=r_{0i}(1-b_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})...\left(B\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; b _iTime effects coefficient for the relative reduction ratio of each frame of upstream;

The maximum of the relative reduction ratio decrease of upstream frame is controlled in 40%～50% scope of the relative reduction ratio of corresponding frame benchmark;

The middle reaches frame is born remaining sharing of load, its relative reduction ratio fluctuation range be controlled at the relative reduction ratio of benchmark ± 60% scope in;

Each frame keeps consistent with the last reduction ratio numerical value of adjusting in the continuous rolling process after the 80th～120 coil.

The present invention is by researching and analysing thermal expansion of rollers in the operation of rolling and abrasional behavior, found out the Changing Pattern of the integrating shape curve of working roll roll surface with rolling time, thereby different roller heat convex degree learning compensation methodes has been proposed at each frame, determined the upstream frame, the middle reaches frame, the trend that frame relative reduction ratio in downstream changes, designed rational load variations function, under the constant prerequisite of second flow amount, the variation of each roll sharing of load is in time by the volume smooth change, there is not mutability, function structure is simple, be easy to adjust, so just guaranteed stability rolling when reduction ratio changes, particularly tension control system and thickness system is stable, considers the control of glacing flatness simultaneously.Therefore, this method has remedied the existence in roller system works dead band and the systematic error of roller model, and control panel convexity and glacing flatness are beneficial to and apply more accurately.

Description of drawings

Fig. 1 is the change curve that seamlessly transits of the method for the invention rolling procedure, Fig. 2 is that the method for the invention adopts the adjusting roller to compensate the increase curve map of the hot convexity that is caused by the roll-force increase, Fig. 3 is the change curve schematic diagram that change of load distributes the exit plate convexity that causes in the specific embodiment two described operations of rolling, and Fig. 4 is that original pair rolling rules (dashed region) are rolled band plate crown comparative graph with new rolling procedure in the rolling cycle.

The specific embodiment

The specific embodiment one: present embodiment is a kind of hot-strip convex degree control method based on the smooth change rolling procedure, it is that rolling-mill housing with rolling hot strip steel is divided into upstream frame, middle reaches frame and downstream frame successively by rolling order, according to steel rolling volume number is with the volume adjustment, concrete method of adjustment is in the operation of rolling of each frame reduction ratio before 80～120 coils:

The relative reduction ratio r of downstream frame _iIncrease by volume according to formula (A):

$r_i=r_{0i}(1+a_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})...\left(A\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; a _iTime effects coefficient for the relative reduction ratio of each frame of downstream;

The maximum of the relative reduction ratio recruitment of downstream frame is controlled in 40%～50% scope of the relative reduction ratio of corresponding frame benchmark;

The relative reduction ratio r of upstream frame _iReduce by volume according to formula (B):

$r_i=r_{0i}(1-b_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})...\left(B\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; b _iTime effects coefficient for the relative reduction ratio of each frame of upstream;

The maximum of the relative reduction ratio decrease of upstream frame is controlled in 40%～50% scope of the relative reduction ratio of corresponding frame benchmark;

The middle reaches frame is born remaining sharing of load, its relative reduction ratio fluctuation range be controlled at the relative reduction ratio of benchmark ± 60% scope in;

Each frame keeps consistent with the last reduction ratio numerical value of adjusting in the continuous rolling process after the 80th～120 coil.

The relative reduction ratio of described each frame benchmark is upstream frame 27～36%, middle reaches frame 24～27%, downstream frame 10～24%.

The time effects coefficient of the relative reduction ratio of each frame is 0～1.

The coil of strip sum of a described rolling unit is in 80～120 scopes.

Operation principle of the present invention is as follows, sees figures.1.and.2.Rules 1 are rolling units when beginning among Fig. 1, and each roll does not possess hot convexity and wearing and tearing, the rolling schedule of formulating by the conventional load distribution method; When rules 2 were rolling mid-terms, each roll had possessed certain hot convexity and wearing and tearing, the rolling schedule that is obtained by rules 1 smooth change; When rules 3 were rolling latter stages, roller heat convex degree learning did not change substantially, the rules that obtained by rules 2 smooth change.

Along with the carrying out of the operation of rolling, the heat that the roll system increases makes in it and can change, and temperature raises.Under the certain condition of heat flow density, so proportional relation of the variation of interior energy and time, and the same proportional relation of variations in temperature and interior energy are proportional relation of variation of temperature and time.

Behind rolling some bands steel, the roll heat exchange is near balance, and roller heat convex degree learning can be similar to following formula and calculate:

$\left.\begin{array}{c}u\left(R\right)=\frac{2\mathrm{\β}}{R}{\∫}_0^R(T_R-T_{R0})\mathrm{rdr}=\mathrm{\β\Δ}\stackrel{\‾}{T_R}R\\ \mathrm{\Δ}{\stackrel{\‾}{T}}_R={\∫}_0^R(T_R-T_{R0})2\mathrm{\πrdr}/\mathrm{\πR}\end{array}\right\}$

In the formula, u (R) is the thermal expansion amount of roll;

Mean temperature variation for roll; β is the roll material linear expansion coefficient; V is a Poisson's ratio; T _RBe the roll real-time temperature; T _R0Be the roll original temperature; R is a roller radius.

Hence one can see that, the proportional relation of the mean temperature of the thermal expansion amount of roll and roll during continuous rolling, and the proportional relation of temperature and rolling time.So proportional relation of the thermal expansion amount of roll and rolling time.

Under the condition that does not form iron scale, the increase in direct ratio of working roller abrasion degree and mill length.Think simultaneously and change reduction ratio not quite the coefficient of friction influence.

With regard to ordinary circumstance, hot convexity makes roll surface along wide parabola shaped to having, and roller heat convex degree learning has considerable influence to strip profile.When rolling unit finished, first frame (to call F1 in the following text, second frame claims F2, and the like) roller heat convex degree learning maximum can reach 250 μ m～300 μ m, and the meeting of F4 reaches 200 μ m～250 μ m, can reach 100 μ m～150 μ m at F7.Hot convexity curve and wear curve is synthetic, just become the integrating shape curve that rolls back working roll roll surface, along with the integrating shape curve convex of carrying out the working roll roll surface of the operation of rolling reduces gradually.

In the downstream frame because the rolled piece reduced thickness, the metal lateral flow a little less than, the control ability of roller also just relatively a little less than, and the situation of upstream frame is just opposite, rolled piece is thicker, the metal lateral flow is stronger, so the control ability of roller is also just stronger.While is owing to the relative downstream of the hot convexity of upstream breast roller frame is bigger than normal, so the effect emphasis of roller should be implemented on the upstream frame, to compensate the bigger hot convexity of its roll, and on the weak side in the downstream frame, the compensation of the hot convexity of downstream frame at this moment is fixed against the raising of rolling load.So along with the relative reduction ratio of rolling process downstream frame should progressively increase, the relative reduction ratio of upstream frame should progressively reduce simultaneously.

Owing to the increase along with rolling volume number of the thermal expansion amount of roll and working roller abrasion degree changes.The relative reduction ratio of each frame also should progressively change along with rolling process so, and this point is a starting point of the present invention, also is that the present invention is different from other convex degree control method part.

Think that actual reduction ratio relatively is the function of institute's steel rolling volume number, if milling train has 7 frames, for the strip crown that can obtain meeting the requirements at last frame and guarantee good glacing flatness, the relative reduction ratio of downstream F5, F6, F7 frame increases by volume along with the increase of rolling time during continuous rolling, that is pursues the volume increase with the increase of roller heat convex degree learning.The increase mode adopts linear forms.

$r_i=r_{0i}(1+a_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; a _iTime effects coefficient for the relative reduction ratio of each frame of downstream;

Pass through a _iControl the amplitude that relative reduction ratio increases.At first the problem of Kao Lving is that the increase of relative reduction ratio can make roll-force increase, and roll-force can not surmount single chassis maximum rolling force scope; Next is to consider that roll-force makes roller heat convex degree learning increase when increasing, and at this moment needs the intervention of suitable roller to be compensated, and has the advantage of not disturbing with other rules variable because hydraulic bending roll is regulated.As shown in Figure 2, it is curve 1 that hot convexity originally-roll-force is closed, and operating point A is more than intact plate shape line F, and when the effective convexity of roll was reduced, hot convexity-roll-force relation curve dropped to curve 2, corresponding to work roll-force P _AIntact plate shape operating point be B, intersect with intact plate shape line or when being tangential on the B point, just can obtain good profile when hot convexity curve descends.

The relative reduction ratio of F1, the F2 of upstream frame, F3 should progressively reduce when the relative reduction ratio of downstream frame should progressively increase.The same employing of the mode that the reduces linear structure function identical with following formula,

$r_i=r_{0i}(1-b_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})$

In the formula, b _iTime effects coefficient for the relative reduction ratio of each frame of upstream;

The F4 frame in middle reaches is born remaining sharing of load.

Behind rolling 80～120 coils, it is saturated that roller heat convex degree learning is tending towards, perhaps change the excursion that rolling schedule may exceed above regulation, keep the sharing of load coefficient of each frame in small scope, to fluctuate from this time, perhaps keep and last consistent the getting final product of adjusting of reduction ratio numerical value, the interior concrete rolling several borders factually roll-force of 80～120 coil scopes can not exceed the maximum rolling force that milling train can bear and determine.

In sum, the variation tendency of the relative reduction ratio of each frame is, rolling when initial, upstream frame reduction ratio is bigger, downstream frame less, rolling mid-term, the reduction ratio of each frame was average relatively, along with rolling process, upstream frame reduction ratio reduces by volume, and the maximum of reduction ratio decrease is controlled in 40%～50% scope of initial phase to reduction ratio relatively.Increasing of downstream by volume, the recruitment of the 5th frame and the relative reduction ratio of the 6th frame is controlled in 50% scope of initial phase to reduction ratio, and the 7th frame emphasis is used for the control of finished strip glacing flatness, and the recruitment of its relative reduction ratio is controlled in 40% scope of initial phase to reduction ratio.The middle reaches frame is born remaining sharing of load, its reduction ratio fluctuation range be controlled at initial phase to reduction ratio ± 60% scope in.The variation of rules finishes behind rolling 80～120 coils.

The specific embodiment two: present embodiment is selected rolling procedure at 120 coils, adopts 7 machine frame rolling mills, and wherein F1, F2, F3 frame are the upstream frame, the F4 frame is the middle reaches frame, F5, F6, F7 frame are the downstream frame, and the relative reduction ratio of each frame benchmark is F1:33～35%, F2:30～33%, F3:27～30%, F4:24～27%, F5:21～24%, F6:16～19%, F7:10～12%.

Adopt the method for the invention that the relative reduction ratio of each frame of finish rolling is set, make it pursue the volume smooth change, thus the strip crown of control band steel, and reduction ratio increase or the mode that reduces adopt the function of linear structure.

Begin when rolling the relative reduction ratio r of control upstream breast roller _iReduce by volume according to formula (B):

$r_i=r_{0i}(1-b_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})...\left(B\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; b _iTime effects coefficient for the relative reduction ratio of each frame of upstream;

The relative reduction ratio r of downstream breast roller _iIncrease by volume according to formula (A):

$r_i=r_{0i}(1+a_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})...\left(A\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; a _iTime effects coefficient for the relative reduction ratio of each frame of downstream;

The middle reaches breast roller is born remaining sharing of load.

Reduction ratio is along with the function that rolling time changes adopts linear forms relatively, the amplitude of variation of reduction ratio can be adjusted by the time effects coefficient of the relative reduction ratio of each frame, make the not sudden change of corresponding frame reduction ratio between volume and the volume, have the feature that seamlessly transits.In concrete operations, the time effects coefficient that above-mentioned formula relates to is according to predefined roll-force, the plate shape index of rolled piece is controlled, the time effects coefficient of relative reduction ratio is within 0～1 scope, but the actual roll-force that requires finally to obtain does not exceed the maximum rolling force that milling train can bear.

When rolling the 1st coil, the A rules of the reduction ratio See Figure of each breast roller, when rolling the 41st coil, the B rules of the reduction ratio See Figure of each breast roller, when rolling the 81st coil, the C rules of the reduction ratio See Figure of each breast roller.

Used rolling schedule when table 1 rolls in fact (reduction ratio relatively)

Rolling result is tested, and the A rules are 60 μ m to C rules convexity difference, variation that can the hot convexity of compensation work roller.The ratio convexity of the finish rolling entrance and exit under these three kinds of rolling schedules is almost equal, finish rolling inlet thickness 26mm when rolling in fact, outlet 2.3mm.In a rolling unit, carrying out along with the operation of rolling, change and to depress allocation model and carry out the transition to B by A and carry out the transition to C again, this method can be controlled convexity in the constant scope, promptly about 80 μ m, shown in heavy line among Fig. 3, wherein 1 of fine line is the A rules, the 2nd, B rules, the 3rd, C rules; Heavy line is A → B → C.As can be seen, as long as suitably revise initial roll crown, then the exit plate convexity can be controlled on the level of any requirement, and remains unchanged substantially in rolling.

The reality of a complete rolling cycle is rolled situation as shown in Figure 4, and strip profile C when adopting above-mentioned new order and traditional rules has been described _H25The comparison that changes.Dashed region changes to 20 μ m for adopting the production board convexity scope of traditional rolling procedure by 100 μ m among the figure, has exceeded the claimed range of desired value.And adopt level and smooth when changing the new order of depressing load institute roll strip profile shown in solid initial point zone among the figure, change to 30 μ m by 60 μ m, satisfy the control requirement of convexity fully.Therefore, theory is calculated and the real process of rolling has all proved, changes the method that rolling load distributes with the level and smooth volume that pursues of the present invention, can be under the prerequisite that guarantees plate shape, and the strip crown of band steel is rolled in effective control.

The specific embodiment three: present embodiment and the specific embodiment two differences are that described milling train is 6 frames, and wherein F1, F2, F3 frame are the upstream frame, and the F4 frame is the middle reaches frame, and F5, F6 frame are the downstream frame.

The process that any material is rolled that the method for the invention can be used for that roll can expand; except steel material of the present invention; also can be used for rolling to copper, aluminium and other materials, as long as use method of the present invention, all should be within protection scope of the present invention.

Claims (7)

1. hot-strip convex degree control method based on the smooth change rolling procedure, it is characterized in that the rolling-mill housing of rolling hot strip steel is divided into upstream frame, middle reaches frame and downstream frame successively by rolling order, according to steel rolling volume number is with the volume adjustment, concrete method of adjustment is in the operation of rolling of each frame reduction ratio before 80～120 coils:

The relative reduction ratio r of downstream frame _iIncrease by volume according to formula (A):

$r_i=r_{0i}(1+a_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})---\left(A\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _ToalIt is the coil of strip sum of a rolling unit; a _iTime effects coefficient for the relative reduction ratio of each frame of downstream;

The maximum of the relative reduction ratio recruitment of downstream frame is controlled in 40%～50% scope of the relative reduction ratio of corresponding frame benchmark;

The relative reduction ratio r of upstream frame _iReduce by volume according to formula (B):

$r_i=r_{0i}(1-b_i\frac{n_{\mathrm{pass}}}{n_{\mathrm{total}}})---\left(B\right)$

In the formula, r _0iBe the relative reduction ratio of each frame benchmark; n _PassBe the volume of steel rolling number; n _TotalIt is the coil of strip sum of a rolling unit; b _iTime effects coefficient for the relative reduction ratio of each frame of upstream;

The maximum of the relative reduction ratio decrease of upstream frame is controlled in 40%～50% scope of the relative reduction ratio of corresponding frame benchmark;

The middle reaches frame is born remaining sharing of load, its relative reduction ratio fluctuation range be controlled at the relative reduction ratio of benchmark ± 60% scope in;

Each frame keeps consistent with the last reduction ratio numerical value of adjusting in the continuous rolling process after the 80th～120 coil.

2. a kind of hot-strip convex degree control method based on the smooth change rolling procedure according to claim 1 is characterized in that the relative reduction ratio of described each frame benchmark is upstream frame 27～36%, middle reaches frame 24～27%, downstream frame 10～24%.

3. a kind of hot-strip convex degree control method based on the smooth change rolling procedure according to claim 1, the time effects coefficient that it is characterized in that the relative reduction ratio of each frame is 0～1.

4. a kind of hot-strip convex degree control method based on the smooth change rolling procedure according to claim 1, the coil of strip sum that it is characterized in that a rolling unit is in 80～120 scopes.

5. according to claim 1,2,3 or 4 described a kind of hot-strip convex degree control methods based on the smooth change rolling procedure, it is characterized in that described hot strip mill is 7 frames, wherein F1, F2, F3 frame are the upstream frame, the F4 frame is the middle reaches frame, and F5, F6, F7 frame are the downstream frame.

6. a kind of hot-strip convex degree control method according to claim 5 based on the smooth change rolling procedure, it is characterized in that the relative reduction ratio of each frame benchmark is, F1:33～35%, F2:30～33%, F3:27～30%, F4:24～27%, F5:21～24%, F6:16～19%, F7:10～12%.

7. according to claim 1,2,3 or 4 described a kind of hot-strip convex degree control methods based on the smooth change rolling procedure, it is characterized in that described hot strip mill is 6 frames, wherein F1, F2, F3 frame are the upstream frame, and the F4 frame is the middle reaches frame, and F5, F6 frame are the downstream frame.

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