CN102303051B - Pipe shape control method for rolling seamless steel pipe by using seven-frame tandem mill - Google Patents

Abstract

The invention discloses a pipe shape control method for rolling a seamless steel pipe by using a seven-frame tandem mill, which aims to provide a control method for processing data by using on-line detection pipe shape information and controlling rolling parameters in real time by integrating thickness errors, ellipticity errors and straightness errors which influence pipe shapes so as to ensure the accuracy of the pipe shapes. The method comprises the following steps of: 1) presetting the rolling parameters; 2) calculating rolling reduction and rolling force according to actually-measured wall thickness, ellipticity and straightness, namely making the rolling reduction, the wall thickness errors, the ellipticity errors and the straightness errors form a matrix, simplifying the matrix to be a corresponding relationship between the rolling reduction and a single parameter by an elimination method, calculating the rolling reduction caused by the wall thickness errors, the rolling reduction caused by the ellipticity errors and the rolling reduction caused by the straightness errors respectively, and calculating the rolling force by using the sum of the calculated rolling reduction caused by the wall thickness errors, the ellipticity errors and the straightness errors; and 3) modifying the rolling force and roller gap numerical values in real time in the rolling process.

Description

Use the pipe shape control method of seven frame tandem mill rolling seamless steel pipes

Technical field

The present invention relates to a kind of pipe shape control method of seamless steel pipe.

Background technology

Seamless steel pipe is mainly used in the fields such as energy development, communications and transportation, frame for movement, chemical plant installations.With the development of World Economics and production technology, the industries such as oil and boiler improve constantly the seamless steel pipe quality requirement, and tubular error control has become one of core technology of seamless steel tube production.The tubular of seamless steel pipe is important control index during steel pipe rolling is produced, refer to steel pipe in thickness difference and straightness error and the ovality etc. of diverse location, tubular error is mainly derived from variation, roll contact condition, the roll thermal deformation of error, the rolling tensile force of error, the roll of variation, the hollow billet material of roll-force, variation of roll gauge etc., and these parameters directly have influence on tubular state and the roll goal of regulation and control of steel pipe.

Tubular control in the roll seamless steel tube process is comprehensive, a complicated process, each link factor such as the roll shape of the roll in the production, rolling technological parameter, as-rolled condition variation might have influence on the tubular quality of product, also has relation uncertain, non-linear, close coupling between each influence factor.At present, tubular control both domestic and external mainly is the independent control method of error.But, because there is interference each other in each error parameter, affect control accuracy.

Summary of the invention

The present invention is in order to overcome weak point of the prior art, provide a kind of by the tubular information of online detection and carry out rational data and process, tubular thickness error, ellipticity error and the straightness error of impact integrated, be rolled the real-time control of parameter, guarantee the control method of tubular precision.

The present invention is achieved through the following technical solutions:

A kind of pipe shape control method of use seven frame tandem mill rolling seamless steel pipes is characterized in that, comprises the steps:

(1) rolling parameter presets:

(1) calculates the ground conth of roll, wear extent and the roll heat distortion amount of roll;

(2) the comprehensive roll forming of calculating roll:

The ground conth of the roll that calculates in the step (1), wear extent and the roll heat distortion amount of roll are carried out the comprehensive roll forming that the strain linear superposition obtains equivalence;

(3) calculate each frame export goal wall thickness, ovality and linearity;

(4) calculate the roll drafts:

In seven frame tandem mills, the roll drafts that 5%, the second frame to the, the five breast roller drafts that 35%, the six breast roller drafts that the first breast roller drafts accounts for overall reduction accounts for overall reduction are 15%, the seven frame of overall reduction is zero;

(5) calculate the roll-force of each frame:

$p_i\left(k\right)={\stackrel{\‾}{p}}_{1,i}\left(k\right)\·F_{1,i}\left(k\right)+{\stackrel{\‾}{p}}_{2,i}\left(k\right)\·F_{2,i}\left(k\right)---\left(1\right)$

In the formula (1):

p _i(k) be the roll-force of i frame k rolling cycle;

It is the average unit force of the k rolling cycle of i frame diameter reducing area;

F _{L, i}(k) be the floor projection of contact area of the k rolling cycle of i frame diameter reducing area;

It is the average unit force of the k rolling cycle of i frame wall-thickness reduction zone;

F _{2, i}(k) be the floor projection of contact area of the k rolling cycle of i frame wall-thickness reduction zone;

(2) wall thickness, ovality and the linearity according to actual measurement calculates rolling drafts and roll-force:

(1) the detection FEEDBACK CONTROL of wall thickness deflection

Adopt the ultrasonic thickness instrument to measure the actual wall thickness value of the first six frame exit steel pipe of tandem mill, with the deviation of the actual wall thickness value of steel pipe measured and target wall thickness value as the wall thickness difference, employing is based on the rolling drafts of each frame of algorithm calculating tandem rolling unit of Digital PID Controller, and computing formula is as follows:

e _i(k)＝ξ·[r _i(k)-y _act，i(k)] (2)

In the formula (2), e _i(k) be the wall thickness difference of the k control cycle of i frame;

r _i(k) be the target wall thickness of i frame;

y _{Act, i}(k) be the actual wall thickness of the k control cycle of i frame;

ξ is the wall thickness deflection adjustment factor, gets 0.6-0.9;

$\mathrm{\Δ}{e}_i\left(k\right)=c_i\·[c_{\mathrm{PF},i}\left(k\right)+\frac{c_{\mathrm{IF},i}\·\underset{j=0}{\overset{k}{\mathrm{\Σ}}}{e}_i\left(j\right)}{c_{\mathrm{BF},i}}]---\left(3\right)$

In the formula (3), Δ e _i(k) be the drafts of the k control cycle wall thickness deflection feedback adjusting of i frame;

c _iThe wall thickness deflection feedback control model that is the i frame is adjusted coefficient, and span is 0.52-0.61;

c _{PF, i}(k) be the wall thickness deflection feedback proportional coefficient of i frame k control cycle, span is 0.23-0.27;

c _{IF, i}Being the wall thickness deflection feedback integral coefficient of i frame, is 0.9 when j=i, and all the other are 0.2;

c _{BF, i}Be the drafts of i frame to the influence coefficient of wall thickness deflection, span is 1.0-1.25;

(2) the detection FEEDBACK CONTROL of ellipticity error

Measure the difference acquisition ovality of maximum gauge and the minimum diameter of tandem mill the 6th frame and the 7th frame exit seamless steel pipe by the eccentric measurer that is installed in tandem mill the 6th frame and the 7th frame exit, take the deviation of the actual ovality of the steel pipe that detects and Target ellipse degree value as foundation, calculate the drafts of each frame of tandem rolling unit, computing formula is as follows:

ΔR _i(k)＝α·[R _i(k)-r _act，i(k)] (4)

In the formula (4), Δ R _i(k) be the ovality difference of the k control cycle of i frame;

R _i(k) be the Target ellipse degree of i frame;

r _{Act, i}(k) be the actual ovality of the k control cycle of i frame;

α is the ellipticity error adjustment factor, and span is 0.34-0.39;

$\mathrm{\Δ}{y}_i\left(k\right)=m_i\·[m_{\mathrm{PF},i}\left(k\right)+\frac{m_{\mathrm{IF},i}\·\underset{j=0}{\overset{k}{\mathrm{\Σ}}}\mathrm{\Δ}{R}_i\left(j\right)}{m_{\mathrm{BF},i}}]---\left(5\right)$

In the formula (5), Δ y _i(k) be the drafts of the k control cycle ellipticity error feedback adjusting of i frame;

m _iThe ellipticity error feedback control model that is the i frame is adjusted coefficient, and span is 0.25-0.31;

m _{PF, i}(k) be the ellipticity error feedback proportional coefficient of i frame k control cycle, span is 0.18-0.23;

m _{IF, i}Being the ellipticity error feedback integral coefficient of i frame, is 0.8 when j=i, and all the other are 0.13;

m _{BF, i}Be the drafts of i frame to the influence coefficient of ellipticity error, span is 1.5-2.1;

(3) the detection FEEDBACK CONTROL of straightness error

At the 5th frame, the 6th frame and the 7th frame exit difference setting-up eccentricity measuring instrument, measure the tube core position of seamless steel pipe by eccentric measurer, the tube core position that connects each measurement point, obtain steel pipe actual flexion value, take the deviation of the target bending value of the steel pipe actual flexion value that detects and steel pipe as foundation, calculate the drafts of tandem rolling unit the 6th frame, computing formula is as follows:

γ _i(k)＝η·[θ _i(k)-φ _act，i(k)] (6)

In the formula (6), γ _i(k) be the linearity difference of the k control cycle of i frame;

θ _i(k) be the target line degree of i frame;

φ _{Act, i}(k) be the actual linearity of the k control cycle of i frame;

η is the straightness error adjustment factor, and span is 0.67-0.75;

$\mathrm{\Δ}{\mathrm{\γ}}_i\left(k\right)=n_i\·[n_{\mathrm{PF},i}\left(k\right)+\frac{n_{\mathrm{IF},i}\·\underset{j=0}{\overset{k}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\γ}}_i\left(j\right)}{n_{\mathrm{BF},i}}]---\left(7\right)$

In the formula (7), Δ γ _i(k) be the drafts of the k control cycle straightness error feedback adjusting of i frame;

n _iThe straightness error feedback control model that is the i frame is adjusted coefficient, and it is 0.37-0.43 for span;

n _{PF, i}(k) be the straightness error feedback proportional coefficient of i frame k control cycle, span is 0.16-0.21;

n _{IF, i}Being the straightness error feedback integral coefficient of i frame, is 0.8 when j=i, and all the other are 0.23;

n _{BF, i}Be the drafts of i frame to the influence coefficient of straightness error, span is 1.1-1.3;

(4) decoupling zero control

The drafts that step (1), step (2) and step (3) are obtained and wall thickness difference, ovality difference, three parameters of linearity difference form matrix, and are as follows:

$\left[\begin{array}{ccc}{a}_{\mathrm{1,1}}& a_{\mathrm{1,2}}& a_{\mathrm{1,3}}\\ a_{\mathrm{2,1}}& a_{\mathrm{2,2}}& a_{\mathrm{2,3}}\\ a_{\mathrm{3,1}}& a_{\mathrm{3,2}}& a_{\mathrm{3,3}}\end{array}\right]\left\{\begin{array}{c}{e}_i\left(k\right)\\ \mathrm{\Δ}{R}_i\left(k\right)\\ {\mathrm{\γ}}_i\left(k\right)\end{array}\right\}=\left\{\begin{array}{c}\mathrm{\Δ}{e}_i\left(k\right)\\ \mathrm{\Δ}{y}_i\left(k\right)\\ \mathrm{\Δ}{\mathrm{\γ}}_i\left(k\right)\end{array}\right\}---\left(8\right)$

In the formula (8):

e _i(k) be the wall thickness difference of the k control cycle of i frame;

Δ R _i(k) be the ovality difference of the k control cycle of i frame;

γ _i(k) be the linearity difference of the k control cycle of i frame;

Δ e _i(k) be the drafts of the k control cycle wall thickness deflection feedback adjusting of i frame;

Δ y _i(k) be the drafts of the k control cycle ellipticity error feedback adjusting of i frame;

Δ γ _i(k) be the drafts of the k control cycle straightness error feedback adjusting of i frame;

a _1,1The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iξ multiplies each other with the wall thickness deflection adjustment factor;

a _1,2The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iWall thickness deflection feedback proportional coefficient c with the i frame _{PF, i}(k) multiply each other;

a _1,3The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iWall thickness deflection feedback proportional coefficient c with the i frame _{PF, i}(k) multiply each other, again divided by the drafts of the i frame influence coefficient c to wall thickness deflection _{BF, i}

a _2,1The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iEllipticity error feedback proportional Coefficient m with the i frame _{PF, i}(k) product;

a _2,2The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iProduct with ellipticity error adjustment factor α;

a _2,3The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iWith the product of ellipticity error adjustment factor α, again divided by the drafts of the i frame influence coefficient m to ellipticity error _{BF, i}

a _3,1The straightness error feedback control model that is the i frame is adjusted coefficient n _iStraightness error feedback proportional coefficient n with the i frame _{PF, i}(k) product is again divided by the drafts of the i frame influence coefficient n to straightness error _{BF, i}

a _3,2The straightness error feedback control model that is the i frame is adjusted coefficient n _iStraightness error feedback proportional coefficient n with the i frame _{PF, i}(k) product;

a _3,3The straightness error feedback control model that is the i frame is adjusted coefficient n _iProduct with straightness error adjustment factor η;

Adopt the elimination be reduced to drafts respectively with the corresponding relation of single parameter, calculate respectively the drafts that drafts that the wall thickness deflection of i frame k control cycle causes, drafts that ellipticity error causes and straightness error cause;

The drafts sum that the drafts that causes with the wall thickness deflection that calculates, the drafts that ellipticity error causes and straightness error cause is calculated the roll-force of each frame of k control cycle as drafts;

(3) in the operation of rolling, revise in real time roll-force and roll gap numerical value

(1) roll-force FEEDBACK CONTROL Mathematical Modeling is:

ΔF _Bi＝k _ali·k _FF·ΔF _Ri (9)

In the formula (9), Δ F _BiBe the roll-force regulated quantity of i frame, i is shelf number;

k _AliThe roll-force feedback control model that is the i frame is adjusted coefficient, is 0.1 when being 0.65, i=7 when being 0.65, i=6 when being 0.65, i=5 when being 0.65, i=4 when being 0.65, i=3 when being 0.9, i=2 during i=1;

k _FFBeing roll-force feedback control model coefficient, is 0.5;

Δ F _RiBe the roll-force variable quantity of i frame, the roll-force of the k control cycle that is namely calculated by formula (1) and the actual roll-force of (k-1) control cycle poor;

As Δ F _BiNumerical value greater than (k-1) actual roll-force of rolling cycle 5% the time, get Δ F _BiBe 5% of (k-1) actual roll-force of rolling cycle, as Δ F _BiNumerical value be less than or equal to (k-1) actual roll-force of rolling cycle 5% the time, get the roll-force of the k control cycle that calculates in the decoupling zero control of step (two) (4) step as new roll-force;

(2) roll gap FEEDBACK CONTROL Mathematical Modeling is:

Δδ _Bi＝k _gδi·k _δδ·Δδ _Ri (10)

In the formula (10), Δ δ _BiBe the Adjustment amount of roll gap of i frame, i is shelf number;

k _{G δ i}The roll gap control model that is the i frame is adjusted coefficient, is 0.1 when being 0.54, i=7 when being 0.54, i=6 when being 0.54, i=5 when being 0.54, i=4 when being 0.54, i=3 when being 0.8, i=2 during i=1;

k _{δ δ}Being roll gap feedback model coefficient, is 1.0;

Δ δ _RiBe the roll gap variable quantity of i frame, the drafts sum that the drafts that the wall thickness deflection of the i frame k control cycle that namely calculates causes, the drafts that ellipticity error causes and straightness error cause and the difference of the actual drafts of (k-1) control cycle;

As Δ δ _BiNumerical value greater than (k-1) actual drafts of rolling cycle 3% the time, make Δ δ _BiEqual (k-1) rolling cycle actual drafts 3%; As Δ δ _BiNumerical value be less than or equal to (k-1) actual drafts of rolling cycle 3% the time, get the rolling drafts sum of drafts that drafts that the wall thickness deflection of the i frame k control cycle that calculates in the decoupling zero control of step (two) (4) step causes, drafts that ellipticity error causes and straightness error cause and (k-1) rolling cycle reality as new rolling drafts.

The present invention has following technique effect:

1, control method of the present invention is by the tubular information of online detection and carry out rational data and process, tubular thickness error, ellipticity error and the straightness error of impact integrated the drafts of each roll of control, avoided each error to control separately the interference that causes, the tubular precision of the seamless steel pipe that obtains is high, simultaneously, avoid drafts adjustment unnecessary in the control procedure, reduced energy consumption.

2, the wearing and tearing of control method of the present invention by ground conth and roll, thermal deformation comprehensive, the compensation roll deformation is on the impact of rolling accuracy.

3, control method of the present invention can controlled rolling power by rolling force model and Rolling roller slit die type and the fluctuation of rolling the drafts mill speed and the tubular sudden change that cause.

4, the dynamic tubular control technology of rolling drafts and roll-force control technology can compare according to actual value and the tubular value of target that measurement result calculates, obtain one group of deviation, by 7 rolls of regulating and control separately, apply corresponding rolling drafts and roll-force to roll respectively, carry out high-precision tubular control, mainly can eliminate the pipe defective of symmetry and asymmetry, dynamic high precision control is tubular, and tubular precision is high.

The specific embodiment

The present invention is described in detail below in conjunction with specific embodiment.

Embodiment:

The basic geometric parameters of seamless steel pipe:

Body external diameter: D=244.5mm; Body external diameter permissible variation: (1.0%～+ 1.0%) D;

Body wall thickness: t=15.11mm; Body wall thickness permissible variation: (12.0%～+ 12.0%) t;

Sleeve pipe ovality: ovality≤1.0%D;

The body flexibility is not more than steel pipe total length 0.50%; The pipe end flexibility is not more than 1.5mm/m.

The strand size:

According to final products specification Φ 244.5mm * 13.84mm, the strand of design is of a size of: Φ 310mm.

Roll adopts cast steel, and material behavior is shown in Table 1.

Table 1 material behavior

The temperature of the operation of rolling is 1100 ℃.

The speed of First roll is 1.59956m/s, and the hollow forging initial velocity is 1.5m/s, and the speed of the 7th roll is 3.28474m/s.

Employed seven frame tandem mills of seamless steel pipe pipe shape control method of the present invention are separately installed with the ultrasonic thickness instrument in the exit of the first six frame, with the wall-thickness measurement difference.Be separately installed with for the difference eccentric measurer of measuring maximum gauge and minimum diameter in the 6th frame and the 7th frame exit, be separately installed with the eccentric measurer of measuring seamless steel pipe tube core position in the exit of the 5th frame, the 6th frame and the 7th frame.

The present invention uses the pipe shape control method of seven frame tandem mill rolling seamless steel pipes, comprises the steps:

(1) rolling parameter presets:

1, adopt conventional method to calculate the ground conth of roll, wearing and tearing and the roll thermal deformation of roll

(1) ground conth is according to the axial distance z of roll arbitrfary point in each frame _i, the roll arbitrfary point radius of curvature ρ _iRadius R with the roll arbitrfary point _iBetween relation calculate according to conventional method, wherein, i is shelf number.Dimension of roller sees Table 2.

Table 2

(2) wearing and tearing of the roll that causes of this production before rolling are calculated and are adopted empirical model, and the formula of place, summit wear extent that calculates roll according to rolling drafts, mill speed, dimension of roller, chilling temperature etc. is as follows:

$Y_i=\frac{W\·e^{f_{i}T}}{\frac{P_i}{L_i\·B_i}\·(1-\frac{\mathrm{\Δ}{V}_i}{V_i})}---\left(1\right)$

In the formula (1): P _iThe pressure of i frame when rolling, N;

L _iThe contact arc length of i frame when rolling, m;

B _iThe steel pipe broadening of i frame when rolling, m;

The needed power of steel pipe movement when W is rolling, N;

Rolling temperature when T is rolling, ℃;

f _iWhen rolling, the roll of i frame and the coefficient of kinetic friction between the steel pipe;

Δ V _iThe roll of i frame and the relative sliding velocity between the steel pipe when rolling, m/s;

V _iThe speed of i breast roller when rolling, m/s;

By rolling 2 tons of calculating, the rolling wear extent on the first breast roller summit of being determined by formula is:

Ten thousand tons of topping roll: Y=1.4285mm/, ten thousand tons of bottom roll: Y=1.0375mm/

The wear extent at roll gap place all is taken as 1/3 of summit wear extent by actual measurement and experience, and the roll summit of this frame and the wear extent between the roll gap place are linear distribution; The wear extent of all the other frames is by formula calculated respectively, and the wearing and tearing between summit and the rod seam distribute and are thought of as linearity.

(3) heat distortion amount of roll is affected by the thermal coefficient of expansion of rolling temperature and roll material, adopts conventional finite element method to calculate.

2, calculate the comprehensive roll forming of roll

The ground conth of the roll that calculates in the step 1, wear extent and the roll heat distortion amount of roll are carried out the comprehensive roll forming that the strain linear superposition obtains equivalence.

3, adopt conventional method to calculate each frame export goal wall thickness, ovality and linearity

The wall thickness of each frame is controlled to be:

The wall thickness control range of the first frame: 24.58-28.58mm

The wall thickness control range of the second frame: 22.91-24.96mm

The wall thickness control range of the 3rd frame: 19.38-23.18mm

The wall thickness control range of the 4th frame: 17.63-19.64mm

The wall thickness control range of the 5th frame: 14.88-16.98mm

The wall thickness control range of the 6th frame: 14.76-15.81mm

The wall thickness control range of the 7th frame: 14.66-15.56mm

Sleeve pipe ovality control: the 6th mill stand control :≤1.5%D; The 7th mill stand control≤0.25%D;

Body linearity: the 5th frame≤1.5mm/m; The 6th mill stand control≤0.9mm/m; The 7th mill stand control≤0.3mm/m.

4, the calculating of roll drafts

In seven frame tandem mills, the roll drafts that 5%, the second frame to the, the five breast roller drafts that 35%, the six breast roller drafts that the first breast roller drafts accounts for overall reduction accounts for overall reduction are 15%, the seven frame of overall reduction is zero.In the present embodiment, the first frame 6.17mm, the second frame 2.65mm, the 3rd frame 2.65mm, the 4th frame 2.65mm, the 5th frame 2.65mm, the 6th frame 0.87mm and the 7th frame 0.0mm.

5, adopt conventional method to calculate the roll-force of each frame

$p_i\left(k\right)={\stackrel{\‾}{p}}_{1,i}\left(k\right)\·F_{1,i}\left(k\right)+{\stackrel{\‾}{p}}_{2,i}\left(k\right)\·F_{2,i}\left(k\right)---\left(2\right)$

In the formula (2):

p _i(k) be the roll-force of i frame k rolling cycle;

Be the average unit force of the k rolling cycle of i frame diameter reducing area, Mpa;

F _{1, i}(k) be the floor projection of contact area of the k rolling cycle of i frame diameter reducing area, m ²

Be the average unit force of the k rolling cycle of i frame wall-thickness reduction zone, Mpa;

F _{2, i}(k) be the floor projection of contact area of the k rolling cycle of i frame wall-thickness reduction zone, m ²

The control of each frame roll-force:

The roll-force control target of First is 2800kN, the second frame roll-force control target is 1960kN, the 3rd roll-force control target is 1170kN, the 4th roll-force control target is 850kN, the 5th roll-force control target is 600kN, the 6th roll-force control target is 350kN, and the 7th roll-force control target is 320kN.

(2) wall thickness, ovality and the linearity according to actual measurement calculates rolling drafts and roll-force

1, the detection FEEDBACK CONTROL of wall thickness deflection

Adopt the ultrasonic thickness instrument to measure the actual wall thickness value of tandem mill each frame exit steel pipe of the first six frame, with the deviation of the actual wall thickness value of steel pipe measured and target wall thickness value as wall thickness deflection, employing is based on the rolling drafts of each frame of algorithm adjustment tandem rolling unit of Digital PID Controller, and computing formula is as follows:

e _i(k)＝ξ·[r _i(k)-y _act，i(k)] (3)

In the formula (3), e _i(k) be the wall thickness difference of the k control cycle of i frame;

r _i(k) be the target wall thickness of i frame;

y _{Act, i}(k) be the actual wall thickness of the k control cycle of i frame;

ξ is the wall thickness deflection adjustment factor, can get 0.6-0.9, and rigidity is large, get large value when temperature is low, and rigidity is little, get the small value when temperature is high, and ξ is 0.8 in the present embodiment.

$\mathrm{\Δ}{e}_i\left(k\right)=c_i\·[c_{\mathrm{PF},i}\left(k\right)+\frac{c_{\mathrm{IF},i}\·\underset{j=0}{\overset{k}{\mathrm{\Σ}}}{e}_i\left(j\right)}{c_{\mathrm{BF},i}}]---\left(4\right)$

In the formula (4), Δ e _i(k) be the drafts of the k control cycle wall thickness deflection feedback adjusting of i frame;

c _iThe wall thickness deflection feedback control model that is the i frame is adjusted coefficient, gets 0.58 in the present embodiment;

c _{PF, i}(k) be the wall thickness deflection feedback proportional coefficient of i frame k control cycle, get 0.25 in the present embodiment;

c _{IF, i}Being the wall thickness deflection feedback integral coefficient of i frame, is 0.9 when j=i, and all the other are 0.2;

c _{BF, i}Be the drafts of i frame to the influence coefficient of wall thickness deflection, get 1.25 in the present embodiment.

2, the detection FEEDBACK CONTROL of ellipticity error

Measure the difference acquisition ovality of maximum gauge and the minimum diameter of tandem mill the 6th frame and the 7th frame exit seamless steel pipe by the eccentric measurer that is installed in tandem mill the 6th frame and the 7th frame exit, take the deviation of the actual ovality of the steel pipe that detects and Target ellipse degree value as foundation, adjust the drafts of each frame of tandem rolling unit, computing formula is as follows:

ΔR _i(k)＝α·[R _i(k)-r _act，i(k)] (5)

In the formula (5), Δ R _i(k) be the ovality difference of the k control cycle of i frame;

R _i(k) be the Target ellipse degree of i frame;

r _{Act, i}(k) be the actual ovality of the k control cycle of i frame;

α is the ellipticity error adjustment factor, gets 0.38 in the present embodiment;

$\mathrm{\Δ}{y}_i\left(k\right)=m_i\·[m_{\mathrm{PF},i}\left(k\right)+\frac{m_{\mathrm{IF},i}\·\underset{j=0}{\overset{k}{\mathrm{\Σ}}}\mathrm{\Δ}{R}_i\left(j\right)}{m_{\mathrm{BF},i}}]---\left(6\right)$

In the formula (6),

Δ y _i(k) be the drafts of the k control cycle ellipticity error feedback adjusting of i frame;

m _iThe ellipticity error feedback control model that is the i frame is adjusted coefficient, and present embodiment gets 0.29;

m _{PF, i}(k) be the ellipticity error feedback proportional coefficient of i frame k control cycle, present embodiment gets 0.20;

m _{IF, i}Being the ellipticity error feedback integral coefficient of i frame, is 0.8 when j=i, and all the other are 0.13;

m _{BF, i}Be the drafts of i frame to the influence coefficient of ellipticity error, present embodiment gets 2.0.

3, the detection FEEDBACK CONTROL of straightness error

At the 5th frame, the 6th frame and the 7th frame exit difference setting-up eccentricity measuring instrument, measure the tube core position of seamless steel pipe by eccentric measurer, the tube core position that connects each measurement point, obtain steel pipe actual flexion value, take the deviation of the target bending value of the steel pipe actual flexion value that detects and steel pipe as foundation, adjust the drafts of tandem rolling unit the 6th frame, make the 6th breaker roll pair poor with the 5th breaker roll and the 7th breaker roll height of formation, make seamless steel pipe produce plastic deformation to eliminate bending error, computing formula is as follows:

γ _i(k)＝η·[θ _i(k)-φ _act,i(k)] (7)

In the formula (7), γ _i(k) be the linearity difference of the k control cycle of i frame;

θ _i(k) be the target line degree of i frame;

φ _{Act, i}(k) be the actual linearity of the k control cycle of i frame;

η is the straightness error adjustment factor, gets 0.72 in the present embodiment;

$\mathrm{\Δ}{\mathrm{\γ}}_i\left(k\right)=n_i\·[n_{\mathrm{PF},i}\left(k\right)+n_{\mathrm{IF},i}\·\frac{\underset{j=0}{\overset{k}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\γ}}_i\left(j\right)}{n_{\mathrm{BF},i}}]---\left(8\right)$

In the formula (8), Δ γ _i(k) be the drafts of the k control cycle straightness error feedback adjusting of i frame;

n _iThe straightness error feedback control model that is the i frame is adjusted coefficient, gets 0.40 in the present embodiment;

n _{PF, i}(k) be the straightness error feedback proportional coefficient of i frame, get 0.20 in the present embodiment;

n _{IF, i}Being the straightness error feedback integral coefficient of i frame, is 0.8 when j=i, and all the other are 0.23;

n _{BF, i}Be the drafts of i frame to the influence coefficient of straightness error, get 1.2 in the present embodiment.

4, decoupling zero control

(1) drafts that step 1, step 2 and step 3 is obtained and wall thickness deflection, ellipticity error, three parameters of straightness error form matrix,

$\left[\begin{array}{ccc}{a}_{\mathrm{1,1}}& a_{\mathrm{1,2}}& a_{\mathrm{1,3}}\\ a_{\mathrm{2,1}}& a_{\mathrm{2,2}}& a_{\mathrm{2,3}}\\ a_{\mathrm{3,1}}& a_{\mathrm{3,2}}& a_{\mathrm{3,3}}\end{array}\right]\left\{\begin{array}{c}{e}_i\left(k\right)\\ \mathrm{\Δ}{R}_i\left(k\right)\\ {\mathrm{\γ}}_i\left(k\right)\end{array}\right\}=\left\{\begin{array}{c}\mathrm{\Δ}{e}_i\left(k\right)\\ \mathrm{\Δ}{y}_i\left(k\right)\\ \mathrm{\Δ}{\mathrm{\γ}}_i\left(k\right)\end{array}\right\}---\left(9\right)$

In the formula (9),

e _i(k) be the wall thickness difference of the k control cycle of i frame;

Δ R _i(k) be the ovality difference of the k control cycle of i frame;

γ _i(k) be the linearity difference of the k control cycle of i frame;

Δ e _i(k) be the drafts of the k control cycle wall thickness deflection feedback adjusting of i frame;

Δ y _i(k) be the drafts of the k control cycle ellipticity error feedback adjusting of i frame;

Δ γ _i(k) be the drafts of the k control cycle straightness error feedback adjusting of i frame;

a _1,1The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iξ multiplies each other with the wall thickness deflection adjustment factor, c _i=0.58, ξ=0.8;

a _1,2The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iWall thickness deflection feedback proportional coefficient c with the i frame _{PF, i}(k) multiply each other c _i=0.58, c _{PF, i}(k)=0.25;

a _1,3The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iWall thickness deflection feedback proportional coefficient c with the i frame _{PF, i}(k) multiply each other, divided by the drafts of the i frame influence coefficient c to wall thickness deflection _{BF, i}, c _i=0.58, c _{PF, i}(k)=0.25, c _{BF, i}=1.25;

a _2,1The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iEllipticity error feedback proportional Coefficient m with the i frame _{PF, i}(k) product, m _i=0.29, m _{PF, i}(k)=0.20;

a _2,2The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iWith the product of ellipticity error adjustment factor α, m _i=0.29, α=0.38;

a _2,3The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iWith the product of ellipticity error adjustment factor α, divided by the drafts of the i frame influence coefficient m to ellipticity error _{BF, i}, m _i=0.29, α=0.38, m _{BF, i}=2.0;

a _3,1The straightness error feedback control model that is the i frame is adjusted coefficient n _iStraightness error feedback proportional coefficient n with the i frame _{PF, i}(k) product is divided by the drafts of the i frame influence coefficient n to straightness error _{BF, i}, n _i=0.40, n _{PF, i}(k)=0.20), n _{BF, i}=1.2;

a _3,2The straightness error feedback control model that is the i frame is adjusted coefficient n _iStraightness error feedback proportional coefficient n with the i frame _{PF, i}(k) product, n _i=0.40, n _{PF, i}(k)=0.20;

a _3,3The straightness error feedback control model that is the i frame is adjusted coefficient n _iWith the product of straightness error adjustment factor η, n _i=0.40, η=0.72.

The matrix of present embodiment is:

$\left[\begin{array}{ccc}0.58\×0.80& 0.58\×0.25& 0.58\×0.25/1.25\\ 0.29\×0.20& 0.29\×0.38& 0.29\×0.38/2.00\\ 0.40\×0.20/1.20& 0.40\×0.20& 0.40\×0.72\end{array}\right]\left\{\begin{array}{c}{e}_i\left(k\right)\\ \mathrm{\Δ}{R}_i\left(k\right)\\ {\mathrm{\γ}}_i\left(k\right)\end{array}\right\}=\left\{\begin{array}{c}\mathrm{\Δ}{e}_i\left(k\right)\\ \mathrm{\Δ}{y}_i\left(k\right)\\ \mathrm{\Δ}{\mathrm{\γ}}_i\left(k\right)\end{array}\right\}---(9-1)$

Adopt the elimination be reduced to drafts respectively with the corresponding relation of single parameter, calculate respectively the drafts that drafts that the wall thickness deflection of i frame k control cycle causes, drafts that ellipticity error causes and straightness error cause;

The drafts sum that the drafts that causes with the wall thickness deflection that calculates, the drafts that ellipticity error causes and straightness error cause is as drafts, with contact and the contact area of plastoelasticity formula (Conventional Calculation Method) calculating roll and steel pipe, calculate at last the roll-force of each frame of k control cycle with Conventional Calculation Method.

(3) in the operation of rolling, revise in real time roll-force and roll gap numerical value

1, roll-force FEEDBACK CONTROL Mathematical Modeling is

ΔF _Bi＝k _ali·k _FF·ΔF _Ri (10)

In the formula (10),

Δ F _BiBe the roll-force regulated quantity of i frame, i is shelf number;

k _AliThe roll-force feedback control model that is the i frame is adjusted coefficient, is 0.1 when being 0.65, i=7 when being 0.65, i=6 when being 0.65, i=5 when being 0.65, i=4 when being 0.65, i=3 when being 0.9, i=2 during i=1.

k _FFBeing roll-force feedback control model coefficient, is 0.5;

Δ F _RiBe the roll-force variable quantity of i frame, namely adopt actual roll-force poor of the roll-force of the k control cycle that formula (2) calculates and (k-1) control cycle;

As Δ F _BiNumerical value greater than (k-1) actual roll-force of rolling cycle 5% the time, get Δ F _BiBe 5% of (k-1) actual roll-force of rolling cycle, as Δ F _BiNumerical value be less than or equal to (k-1) actual roll-force of rolling cycle 5% the time, get the roll-force of the k control cycle that calculates in the decoupling zero control of step (two) the 4th step as new roll-force.

2, roll gap FEEDBACK CONTROL Mathematical Modeling is

Δδ _Bi＝k _gδi·k _δδ·Δδ _Ri (11)

In the formula (11), Δ δ _BiBe the Adjustment amount of roll gap of i frame, i=1,2 ..., 7, be shelf number;

k _{G δ i}The roll gap control model that is the i frame is adjusted coefficient, is 0.1 when being 0.54, i=7 when being 0.54, i=6 when being 0.54, i=5 when being 0.54, i=4 when being 0.54, i=3 when being 0.8, i=2 during i=1.

k _{δ δ}Being roll gap feedback model coefficient, is 1.0;

Δ δ _RiBe the roll gap variable quantity of i frame, the drafts sum that the drafts that the wall thickness deflection of the i frame k control cycle that namely calculates causes, the drafts that ellipticity error causes and straightness error cause and the difference of the actual drafts of (k-1) control cycle;

As Δ δ _BiNumerical value greater than (k-1) actual drafts of rolling cycle 3% the time, make Δ δ _BiEqual (k-1) rolling cycle actual drafts 3%; As Δ δ _BiNumerical value be less than or equal to (k-1) actual drafts of rolling cycle 3% the time, get the rolling drafts sum of drafts that drafts that the wall thickness deflection of the i frame k control cycle that calculates in the decoupling zero control of step (two) the 4th step causes, drafts that ellipticity error causes and straightness error cause and (k-1) rolling cycle reality as new rolling drafts.

After adopting above-mentioned control method rolling, the finished product seamless steel pipe of minute 25 batches of different heats of sampling is got 760 sample pipes, the geometry of having tested body altogether.After the test, the check data of geometry has been carried out statistical analysis.Seamless steel pipe has good shape, and maximum linear degree error is below 0.6mm/m; Maximum ovality is below 0.35%; The maximum gauge error is below 0.5%D; The thickest error is below 5.0%t.

Claims (1)

1. a pipe shape control method that uses seven frame tandem mill rolling seamless steel pipes is characterized in that, comprises the steps:

(1) rolling parameter presets:

(1) calculates the ground conth of roll, wear extent and the roll heat distortion amount of roll;

(2) the comprehensive roll forming of calculating roll:

The ground conth of the roll that calculates in the step (1), wear extent and the roll heat distortion amount of roll are carried out the comprehensive roll forming that the strain linear superposition obtains equivalence;

(3) calculate each frame export goal wall thickness, ovality and linearity;

(4) calculate the roll drafts:

In seven frame tandem mills, the roll drafts that 5%, the second frame to the, the five breast roller drafts that 35%, the six breast roller drafts that the first breast roller drafts accounts for overall reduction accounts for overall reduction are 15%, the seven frame of overall reduction is zero;

(5) calculate the roll-force of each frame:

In the formula (1):

p _i(k) be the roll-force of i frame k rolling cycle;

It is the average unit force of the k rolling cycle of i frame diameter reducing area;

F _{1, i}(k) be the floor projection of contact area of the k rolling cycle of i frame diameter reducing area;

It is the average unit force of the k rolling cycle of i frame wall-thickness reduction zone;

F _{2, i}(k) be the floor projection of contact area of the k rolling cycle of i frame wall-thickness reduction zone;

(2) wall thickness, ovality and the linearity according to actual measurement calculates rolling drafts and roll-force:

(1) the detection FEEDBACK CONTROL of wall thickness deflection

Adopt the ultrasonic thickness instrument to measure the actual wall thickness value of the first six frame exit steel pipe of tandem mill, with the deviation of the actual wall thickness value of steel pipe measured and target wall thickness value as the wall thickness difference, employing is based on the rolling drafts of each frame of algorithm calculating tandem rolling unit of Digital PID Controller, and computing formula is as follows:

e _i(k)＝ξ·[r _i(k)-y _act，i(k)] (2)

In the formula (2), e _i(k) be the wall thickness difference of the k control cycle of i frame;

r _i(k) be the target wall thickness of i frame;

y _{Act, i}(k) be the actual wall thickness of the k control cycle of i frame;

ξ is the wall thickness deflection adjustment factor, gets 0.6-0.9;

In the formula (3), Δ e _i(k) be the drafts of the k control cycle wall thickness deflection feedback adjusting of i frame;

c _iThe wall thickness deflection feedback control model that is the i frame is adjusted coefficient, and span is 0.52-0.61;

c _{PF, i}(k) be the wall thickness deflection feedback proportional coefficient of i frame k control cycle, span is 0.23-0.27;

c _{IF, i}Being the wall thickness deflection feedback integral coefficient of i frame, is 0.9 when j=i, and all the other are 0.2;

c _{BF, i}Be the drafts of i frame to the influence coefficient of wall thickness deflection, span is 1.0-1.25;

(2) the detection FEEDBACK CONTROL of ellipticity error

Measure the difference acquisition ovality of maximum gauge and the minimum diameter of tandem mill the 6th frame and the 7th frame exit seamless steel pipe by the eccentric measurer that is installed in tandem mill the 6th frame and the 7th frame exit, take the deviation of the actual ovality of the steel pipe that detects and Target ellipse degree value as foundation, calculate the drafts of each frame of tandem rolling unit, computing formula is as follows:

ΔR _i(k)＝α·[R _i(k)-r _act，i(k)] (4)

In the formula (4), Δ R _i(k) be the ovality difference of the k control cycle of i frame;

R _i(k) be the Target ellipse degree of i frame;

r _{Act, i}(k) be the actual ovality of the k control cycle of i frame;

α is the ellipticity error adjustment factor, and span is 0.34-0.39;

In the formula (5), Δ y _i(k) be the drafts of the k control cycle ellipticity error feedback adjusting of i frame;

m _iThe ellipticity error feedback control model that is the i frame is adjusted coefficient, and span is 0.25-0.31;

m _{PF, i}(k) be the ellipticity error feedback proportional coefficient of i frame k control cycle, span is 0.18-0.23;

m _{IF, i}Being the ellipticity error feedback integral coefficient of i frame, is 0.8 when j=i, and all the other are 0.13;

m _{BF, i}Be the drafts of i frame to the influence coefficient of ellipticity error, span is 1.5-2.1;

(3) the detection FEEDBACK CONTROL of straightness error

At the 5th frame, the 6th frame and the 7th frame exit difference setting-up eccentricity measuring instrument, measure the tube core position of seamless steel pipe by eccentric measurer, the tube core position that connects each measurement point, obtain steel pipe actual flexion value, take the deviation of the target bending value of the steel pipe actual flexion value that detects and steel pipe as foundation, calculate the drafts of tandem rolling unit the 6th frame, computing formula is as follows:

γ _i(k)＝η·[θ _i(k)-φ _act，i(k)] (6)

In the formula (6), γ _i(k) be the linearity difference of the k control cycle of i frame;

θ _i(k) be the target line degree of i frame;

φ _{Act, i}(k) be the actual linearity of the k control cycle of i frame;

η is the straightness error adjustment factor, and span is 0.67-0.75;

In the formula (7), Δ γ _i(k) be the drafts of the k control cycle straightness error feedback adjusting of i frame;

n _iThe straightness error feedback control model that is the i frame is adjusted coefficient, and its span is 0.37-0.43;

n _{PF, i}(k) be the straightness error feedback proportional coefficient of i frame k control cycle, span is 0.16-0.21;

n _{IF, i}Being the straightness error feedback integral coefficient of i frame, is 0.8 when j=i, and all the other are 0.23;

n _{BF, i}Be the drafts of i frame to the influence coefficient of straightness error, span is 1.1-1.3;

(4) decoupling zero control

The drafts that step (1), step (2) and step (3) are obtained and wall thickness difference, ovality difference, three parameters of linearity difference form matrix, and are as follows:

In the formula (8):

e _i(k) be the wall thickness difference of the k control cycle of i frame;

Δ R _i(k) be the ovality difference of the k control cycle of i frame;

γ _i(k) be the linearity difference of the k control cycle of i frame;

Δ e _i(k) be the drafts of the k control cycle wall thickness deflection feedback adjusting of i frame;

Δ y _i(k) be the drafts of the k control cycle ellipticity error feedback adjusting of i frame;

Δ γ _i(k) be the drafts of the k control cycle straightness error feedback adjusting of i frame;

a _1,1The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iξ multiplies each other with the wall thickness deflection adjustment factor;

a _1,2The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iWall thickness deflection feedback proportional coefficient c with the i frame _{PF, i}(k) multiply each other;

a _1,3The wall thickness deflection feedback control model that is the i frame is adjusted coefficient c _iWall thickness deflection feedback proportional coefficient c with the i frame _{PF, i}(k) multiply each other, again divided by the drafts of the i frame influence coefficient c to wall thickness deflection _{BF, i}

a _2,1The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iEllipticity error feedback proportional Coefficient m with the i frame _{PF, i}(k) product;

a _2,2The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iProduct with ellipticity error adjustment factor α;

a _2,3The ellipticity error feedback control model that is the i frame is adjusted Coefficient m _iWith the product of ellipticity error adjustment factor α, again divided by the drafts of the i frame influence coefficient m to ellipticity error _{BF, i}

a _3,1The straightness error feedback control model that is the i frame is adjusted coefficient n _iStraightness error feedback proportional coefficient n with the i frame _{PF, i}(k) product is again divided by the drafts of the i frame influence coefficient n to straightness error _{BF, i}

a _3,2The straightness error feedback control model that is the i frame is adjusted coefficient n _iStraightness error feedback proportional coefficient n with the i frame _{PF, i}(k) product;

a _3,3The straightness error feedback control model that is the i frame is adjusted coefficient n _iProduct with straightness error adjustment factor η;

Adopt the elimination be reduced to drafts respectively with the corresponding relation of single parameter, calculate respectively the drafts that drafts that the wall thickness deflection of i frame k control cycle causes, drafts that ellipticity error causes and straightness error cause;

The drafts sum that the drafts that causes with the wall thickness deflection that calculates, the drafts that ellipticity error causes and straightness error cause is calculated the roll-force of each frame of k control cycle as drafts;

(3) in the operation of rolling, revise in real time roll-force and roll gap numerical value

(1) roll-force FEEDBACK CONTROL Mathematical Modeling is:

ΔF _Bi＝k _ali·k _FF·ΔF _Ri (9)

In the formula (9), Δ F _BiBe the roll-force regulated quantity of i frame, i is shelf number;

k _AliThe roll-force feedback control model that is the i frame is adjusted coefficient, is 0.1 when being 0.65, i=7 when being 0.65, i=6 when being 0.65, i=5 when being 0.65, i=4 when being 0.65, i=3 when being 0.9, i=2 during i=1;

k _FFBeing roll-force feedback control model coefficient, is 0.5;

Δ F _RiBe the roll-force variable quantity of i frame, the roll-force of the k control cycle that is namely calculated by formula (1) and the actual roll-force of (k-1) control cycle poor;

As Δ F _BiNumerical value greater than (k-1) actual roll-force of rolling cycle 5% the time, get Δ F _BiBe 5% of (k-1) actual roll-force of rolling cycle, as Δ F _BiNumerical value be less than or equal to (k-1) actual roll-force of rolling cycle 5% the time, get the roll-force of the k control cycle that calculates in the decoupling zero control of step (two) (4) step as new roll-force;

(2) roll gap FEEDBACK CONTROL Mathematical Modeling is:

Δδ _Bi＝k _gδi·k _δδ·Δδ _Ri (10)

In the formula (10), Δ δ _BiBe the Adjustment amount of roll gap of i frame, i is shelf number;

k _{G δ i}The roll gap control model that is the i frame is adjusted coefficient, is 0.1 when being 0.54, i=7 when being 0.54, i=6 when being 0.54, i=5 when being 0.54, i=4 when being 0.54, i=3 when being 0.8, i=2 during i=1;

k _{δ δ}Being roll gap feedback model coefficient, is 1.0;

Δ δ _RiBe the roll gap variable quantity of i frame, the drafts sum that the drafts that the wall thickness deflection of the i frame k control cycle that namely calculates causes, the drafts that ellipticity error causes and straightness error cause and the difference of the actual drafts of (k-1) control cycle;

As Δ δ _BiNumerical value greater than (k-1) actual drafts of rolling cycle 3% the time, make Δ δ _BiEqual (k-1) rolling cycle actual drafts 3%; As Δ δ _BiNumerical value be less than or equal to (k-1) actual drafts of rolling cycle 3% the time, get the rolling drafts sum of drafts that drafts that the wall thickness deflection of the i frame k control cycle that calculates in the decoupling zero control of step (two) (4) step causes, drafts that ellipticity error causes and straightness error cause and (k-1) rolling cycle reality as new rolling drafts.