CN103203369A - Plate shape control method for hot-rolled high-strength thin strip steel - Google Patents

Abstract

The invention provides a strip shape control method for hot-rolled high-strength thin strip steel. The finishing rolling unit adopts a work roll traverse mill, the roll profile of the work roll adopts a cosine roll profile curve, and the roll profile of the backup roll adopts the technology of variable contact backup roll profile. Implement the high-frequency and large-stroke roll shifting strategy. The first four finishing mills make the proportional crown of the strip reach the set target proportional crown, and the subsequent rolling mills maintain a constant proportional crown. The flatness target value is 0-5IU, laminar flow Cooling adopts edge shielding technology, and the strip rolling rhythm is controlled at 135-145s/coil. Through the integrated design of the shape control system such as machine configuration, roll shape design, process system and control model, the problems of large shape fluctuations and uncontrolled composite wave shapes of high-strength thin strip steel plates during the rolling process are solved, making hot rolling The flatness of high-strength thin strip steel can be controlled to a high standard level within 20IU, thereby greatly improving the shape quality of high-strength thin strip steel and reducing the failure rate.

Description

The board-shape control method of the high-strength strip steel of a kind of hot rolling

Technical field

The invention belongs to the steel rolling process technical field, particularly the board-shape control method of the high-strength strip steel of a kind of hot rolling.

Background technology

So-called high strength strip steel refers to the high-strength strip steel of hot rolling of thickness≤2.0mm, yield strength 〉=550MPa.Because high strength strip steel has intensity height, in light weight, series of advantages such as material consumption is few, saving cost, be the economic class steel of a kind of " environmental protection ", sustainable development, therefore be widely used in the industry such as automobile, container at home and abroad.Yet, along with improving constantly of industrial automation level, though its thickness of high strength strip steel, width, structure property etc. can both satisfy user's demand, the problem that palette shape does not conform to but becomes increasingly conspicuous, particularly not controlled problems such as big (glacing flatness fluctuation range 124-310IU), compound shape wave of belt plate shape fluctuation, non-specification shape wave have become a big difficult point of plate shape control in the high strength strip steel rolling, and are seriously restricting the strip shape quality qualification rate of high-strength strip steel.

Summary of the invention

The object of the present invention is to provide the board-shape control method of the high-strength strip steel of a kind of hot rolling, namely by plat control systems such as type configuration, roll design, process system and control model being carried out the conformability design, solve in the operation of rolling not controlled problems such as high-strength strip steel plate shape fluctuation is big, compound shape wave, thereby effectively improve high-strength strip steel plate shape quality.

For this reason, the technical solution taked of the present invention is:

The board-shape control method of the high-strength strip steel of a kind of hot rolling is characterized in that, for the high-strength strip steel of the hot rolling of thickness≤2.0mm, yield strength 〉=550MPa, the concrete grammar of its plate shape control is:

1, the hot fine rolling unit is from first finishing mill F ₁To last frame finishing mill F _nAll adopting the work roll shifting milling train is WRS, and n is continuous hot-rolling mill frame sum;

2, working roller adopts the cosine roller curve, and its working roller curve equation is:

$\begin{array}{cc}{C}_w\left(y\right)=\frac{C}{2}\cos \frac{y_s}{l_w}\underset{\÷}{\÷}\cos \frac{s}{2}\÷& y(\frac{l_w}{2},\frac{l_w}{2})\end{array}$

In the formula, C is the working roller amplitude, μ m; _sBe cosine function cornerite variable; l _wBe working roll barrel length, mm; Y is for being the axial coordinate of initial point with body of roll mid point;

Each frame finishing mill working roller designs according to the constant principle of band steel ratio convexity;

It is the VCR technology that the backing roll roll shape adopts change contact backing roll roll forming, and its backing roll roller curve equation is;

C _b(y)=a ₀+a ₁*y+a ₂*y ²+a ₃*y ³+a ₄*y ⁴+a ₅*y ⁵+a ₆*y ⁶

In the formula, a ₀, a ₁, a ₂, a ₃, a ₄, a ₅, a ₆Be each time of backing roll roller curve coefficient; Y is for being the axial coordinate of initial point with the arbitrary end of the body of roll;

3, the big stroke roll shifting of high-frequency strategy is adopted in roll shifting, roll shifting step-length 10-15mm/ time, and roll shifting frequency 1-2 volume/time, roll shifting stroke 100-150mm;

4, reasonable distribution mill load, first finishing mill F ₁With second finishing mill F ₂Adopt and depress reduction ratio 49%-54%, the 3rd finishing mill F greatly ₃To n-1 frame finishing mill F _N-1Reduction ratio remains on 25-40%, last frame F _nReduction ratio remains on 8-10%;

5, the control of plate shape is taked at F ₁-F ₄Finishing mill makes band steel ratio convexity reach target setting ratio convexity, at F ₅-F _nFinishing mill keeps constant proportion example convexity, and the assurance strip profile and flatness is controlled all the time in good area; And carry out work roll bending force feedback control according to actual measurement strip profile and flatness and convexity deviation signal, guarantee plate shape and rolling stability between poised state between frame and frame; Simultaneously, with the fluctuation of draught pressure, make bending roller force make corresponding compensatory adjustment, keep the carrying roll gap shape, avoid owing to rolling temperature, supplied materials varied in thickness cause the draught pressure fluctuation;

6, plate shape glacing flatness desired value span is at 0-5IU, with the influence of compensation temperature to belt plate shape;

7, the edge-masking technology is adopted in the laminar flow cooling, and the strip edge portion scope of blocking is 100-150mm;

8, the control of belt steel rolling rhythm is rolled up at 135-145s/.

Described seven finishing mill working roller parameters according to the constant principle design of band steel ratio convexity are as shown in table 1:

Seven finishing mill working rollers of table 1 parameter list

As shown in table 2 for each each time of backing roll roller curve of seven finishing mills coefficient:

Each time of seven finishing mill backing rolls of table 2 roll shape parameter list

Beneficial effect of the present invention is:

The present invention is by carrying out the conformability design to plat control systems such as type configuration, roll design, process system and control models, solved the not controlled problem of high-strength strip steel plate shape big, the compound shape wave of fluctuation in the operation of rolling, make the high-strength strip steel of hot rolling glacing flatness can be controlled to 20IU with interior high standard level, thereby greatly improved high-strength strip steel plate shape quality, reduced disqualification rate.

Description of drawings

Fig. 1 is seven finishing mill technology arrangement schematic diagrames.

Among the figure: F ₁, F ₂, F ₃, F ₄, F ₅, F ₆, F ₇Be respectively first, second, the 3rd, the 4th, the 5th, the 6th, the 7th finishing mill.1 is the band steel, and 2 is the plate profile instrument table, and 3 is the convexity instrument, 4 cooling facility for laminar flow that block for band edge portion, and 6 is plate shape automatic control system, 51,52,53,54,55,56,57 are respectively F ₁, F ₂, F ₃, F ₄, F ₅, F ₆, F ₇Corresponding hydraulic bending roll.

The specific embodiment

Below, be that AS600MC, yield strength 600MPa, finished product thickness 2.0mm are example with seven rolling materials of mm finishing mill unit of hot continuous rolling 1580mm, the invention will be further described.

As seen from Figure 1, band steel 1 passes F successively ₁, F ₂, F ₃, F ₄, F ₅, F ₆, F ₇After reaching plate profile instrument table 2, convexity instrument 3, again through having the cooling facility for laminar flow 4 of edge-masking, in the whole operation of rolling, plate shape automatic control system 6 is adjusted F according to belt plate shape control needs ₁-F ₇The hydraulic bending roll 51,52,53,54,55,56,57 of each rolling mill.

The elementary tactics of plate shape control of the present invention is, at F ₁-F ₄Make band steel ratio convexity reach target setting ratio convexity after four finishing mills are rolling, simultaneously at F ₅-F ₇Three finishing mills keep constant proportion example convexity substantially, with assurance target glacing flatness, thereby guarantee that strip profile and flatness is controlled in good area all the time in mm finishing mill unit.

F ₁, F ₂, F ₃, F ₄, F ₅, F ₆, F ₇All adopt WRS(work roll shifting milling train), the working roller curve equation is:

$\begin{array}{cc}{C}_w\left(y\right)=\frac{C}{2}\cos \frac{y_s}{l_w}\underset{\÷}{\÷}\cos \frac{s}{2}\÷& y(\frac{l_w}{2},\frac{l_w}{2})\end{array}$

Wherein, C is the working roller amplitude, μ m; _sBe cosine function cornerite variable; l _wBe working roll barrel length, mm; Y is for being the axial coordinate of initial point with body of roll mid point.

Working roller designs each frame working roller parameter such as table 3 according to the constant principle of each frame band steel ratio convexity:

Table 3 working roller parameter

Finishing mill

F 1

F 2

F 3

F 4

F 5

F 6

F 7

C

-170μm

-170μm

-120μm

-90μm

-75μm

-70μm

-65μm

s

2π

2π

2π

2π

2π

2π

2π

Backing roll roller curve equation is:

C _b(y)=a ₀+a ₁*y+a ₂*y ²+a ₃*y ³+a ₄*y ⁴+a ₅*y ⁵+a ₆*y ⁶

Wherein, a ₀, a ₁, a ₂, a _,, a ₄, a ₅, a ₆Be each time of backing roll roller curve coefficient; Y is for being the axial coordinate of initial point with the arbitrary end of the body of roll.

For simplifying the grinding roller process management, improve grinding roller efficient, each finishing mill backing roll parameter value is identical, and its backing roll roll shape parameter sees Table 4.

Each time of table 4 backing roll roll shape parameter

Coefficient entry

a 0

a 1

a 2

a 3

a 4

a 5

a 6

Parameter

0.00

2.784e-04

-9.389e-07

1.663e-09

-1.630e-12

8.384e-16

-1.768e-19

。

F ₁-F ₇The roll shifting strategy of seven finishing mills all adopts the roll shifting step-length 15mm/ time, roll shifting frequency 1 volume/time, roll shifting stroke 120mm.

The reasonable distribution mill load, F ₁-F ₇Reduction ratio distribute and to see Table 5.

Each frame reduction ratio of table 5 finish rolling distributes

Finishing mill	F1	F2	F3	F4	F5	F6	F7
								Reduction ratio	52%	49%	39%	37%	28%	17%	9%

Input board shape automatic control system 6, plate shape glacing flatness desired value is got 3IU, and the convexity desired value is got 55 μ m.Before band steel 1 did not enter F1, plate shape automatic control system 6 was finished the hydraulic bending roll power value of seven finishing mills of F1-F7 according to the processing parameter setting of band steel 1, thereby guaranteed band steel 1 head strip shape quality and wear band stability.After band steel 1 entered into each frame finishing mill, plate shape automatic control system 6 made the hydraulic bending roll 51,52,53,54,55,56,57 of each frame finishing mill make corresponding compensatory adjustment with some cycles with the fluctuation of draught pressure, keeps carrying roll gap shape.After band steel 1 passes plate profile instrument table 2, convexity instrument 3, strip profile and flatness and convexity deviation signal that plate shape automatic control system 6 detects according to plate profile instrument table 2, convexity instrument 3, regulate hydraulic bending roll 51,52,53,54,55,56,57 and carry out FEEDBACK CONTROL, thereby band steel 1 glacing flatness in mm finishing mill unit is controlled all the time in good area, guaranteed glacing flatness and the convexity desired value of band steel 1 total length.

Band steel 1 can enter into the cooling facility for laminar flow 4 that band edge portion blocks through after plate profile instrument table 2, the convexity instrument 3, and it is 120mm that length is blocked in the strip edge portion of the cooling facility for laminar flow 4 that band edge portion blocks; The control of band steel 1 rolling rhythm is rolled up at 140s/.Adopt the high-strength strip steel of AS600MC of the thickness 2.0mm of said method production, its glacing flatness can control to 12IU with interior high standard level.

Claims (3)

1. A flatness control method of hot-rolled high-strength thin strip steel, characterized in that, for the hot-rolled high-strength thin strip steel of thickness≤2.0mm, yield strength≥550MPa, the concrete method of its flatness control is: (1) The hot-rolling finishing unit adopts the work roll traverse rolling mill (WRS) from the first finishing mill _F1 to the last finishing mill _Fn , and n is the total number of hot rolling mill stands; (2) The roll profile of the work roll adopts the cosine roll profile curve, and the roll profile curve equation of the work roll is: $\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\frac{{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}\underset{<span\; class="notranslate">\; \&divide;</span>}{<span\; class="notranslate">\; \&divide;</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&divide;</span>& \mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>\end{array}$ In the formula, C is the roll shape amplitude of the work roll, μm; _s is the wrap angle variable of the cosine function; l _w is the length of the work roll body, mm; y is the axial coordinate with the middle point of the roll body as the origin; The work roll profile of each finishing mill is designed according to the principle of constant strip crown; The roll shape of the back-up roll adopts the variable-contact back-up roll shape, or VCR technology, and the roll shape curve equation of the back-up roll is: C _b (y)=a ₀ +a ₁ *y+a ₂ *y ² +a ₃ *y ³ +a ₄ *y ⁴ +a ₅ *y ⁵ +a ₆ *y ⁶ In the formula, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ , a ₅ , and a ₆ are the sub-term coefficients of the roll shape curve of the back-up roll; y is the axial coordinate with any end of the roll body as the origin; (3) Roll shifting adopts a high-frequency and large-stroke roll shifting strategy, with a roll shifting step length of 10-15mm/time, a roll shifting frequency of 1-2 rolls/time, and a roll shifting stroke of 100-150mm; (4) Reasonably distribute the load of the rolling mills. The first finishing mill F ₁ and the second finishing mill F ₂ adopt large reduction, with a reduction rate of 49%-54%, and the third finishing mill F ₃ to n-1 The reduction rate of F _n-1 of the finishing stand is maintained at 25-40%, and the reduction rate of F _n of the last stand is maintained at 8-10%; (5) Flatness control is adopted in the F ₁ -F ₄ finishing mill to make the proportional crown of the strip reach the set target proportional crown, and maintain a constant proportional crown in the F ₅ -F _n finishing mill to ensure the flatness of the strip It is always controlled in a good area; and the work roll bending force feedback control is carried out according to the measured strip flatness and crown deviation signals to ensure the balance state between the racks and the shape and rolling stability between the racks; at the same time, As the rolling pressure fluctuates, make corresponding compensatory adjustments to the bending force, maintain the shape of the bearing roll gap, and avoid rolling pressure fluctuations caused by changes in rolling temperature and incoming material thickness; (6) The flatness target value ranges from 0-5IU to compensate for the influence of temperature on strip shape; (7) Laminar flow cooling adopts edge shielding technology, and the strip edge shielding range is 100-150mm; (8) The strip rolling rhythm is controlled at 135-145s/coil. 2. the shape control method of hot-rolled high-strength thin strip steel according to claim 1 is characterized in that, according to the constant principle design of strip crown, the roll shape parameters of the seven finishing mill work rolls are as table 1: Table 1 Parameters of the work roll profile of the seven-stand finishing mill

. 3. the flatness control method of hot-rolled high-strength thin strip steel according to claim 1, is characterized in that, each sub-term coefficient of each back-up roll profile curve of seven finishing mills is as table 2: Table 2 Parameters of each sub-item of the back-up roll profile of the seven-stand finishing mill