CN111850450B - Zinc layer control method for differential thickness coating strip steel - Google Patents

Zinc layer control method for differential thickness coating strip steel Download PDF

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CN111850450B
CN111850450B CN201910353048.3A CN201910353048A CN111850450B CN 111850450 B CN111850450 B CN 111850450B CN 201910353048 A CN201910353048 A CN 201910353048A CN 111850450 B CN111850450 B CN 111850450B
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strip steel
pressure
air knife
thickness
coating
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CN111850450A (en
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王宏学
贾银芳
金尧成
张永雪
李爽
李刚
汤红生
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Shanghai Meishan Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
    • C23C2/16—Removing excess of molten coatings; Controlling or regulating the coating thickness using fluids under pressure, e.g. air knives
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/042—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
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  • Coating With Molten Metal (AREA)

Abstract

The invention relates to a zinc layer control method for differential thickness coating strip steel, which comprises the following steps: step one, preparing data, step two, judging a control mode, and accordingly determining whether to execute the step three to pre-calculate the pressure in a differential thickness control mode or to execute the step four to finely control the pressure of the air knife; step three, pre-calculating the pressure in a differential thickness control mode, calculating a pressure set value PT of the upper surface of the strip steel and a pressure set value PB of the lower surface of the strip steel after the transition of the coating specification, and respectively taking the pressure values as the adjusted air knife pressure P1(t +1) of the upper surface of the strip steel and the adjusted air knife pressure P2(t +1) of the lower surface of the strip steel, and then executing a step five; fine adjusting the air knife pressure of the upper surface and the lower surface of the strip steel; and step five, performing coating thickness control by using the adjusted air knife pressure of the upper surface and the lower surface of the strip steel, and then returning to execute the step one. The invention has better real-time performance on the target value control condition in the whole process, has small product quality fluctuation and is not easy to generate careless omission or large-area quality objections.

Description

Zinc layer control method for differential thickness coating strip steel
Technical Field
The invention relates to a zinc layer control method for strip steel with a differential thick coating, belonging to the technical field of hot galvanizing.
Background
In the control of the production process of a hot galvanizing unit, the control of the thickness of a zinc layer is very important and is divided into equal-thickness coating control and differential-thickness coating control. The quality of the control of the coating directly affects the quality and the production cost of the product, and the excessive thickness of the coating not only wastes the raw material zinc ingot and causes the waste of the production cost, but also affects the welding performance, the coating adhesive force, the coating anti-pulverization performance and the like of the product. Too thin a coating may degrade the corrosion resistance of the product and may be unacceptable to the user.
At present, most of domestic steel mill enterprises are mainly controlled by manually setting air knife distance and air knife pressure according to the experience of operators, and the operation is lagged, the quality fluctuation is large, and careless leakage is easy to occur, so that large-area quality objections appear. Some enterprises for realizing automatic control of the thickness of the coating are generally only suitable for controlling the coating with the same thickness, and the traditional manual operation method is adopted for controlling the coating with the different thickness.
The Chinese patent publication No. CN102912275.A, an automatic control system for the coating thickness of a hot dip galvanizing line, discloses a control method for a constant-thickness coating, which adopts a least square method to describe the nonlinear relation between the coating thickness cw and the strip steel speed v, the air knife distance d and the air knife pressure p when the coating thickness set value or the unit speed changes, and mainly adopts feedforward control to calculate the pressure set value. However, since feedforward control and predictive control do not take into account plating deviation correction and control compensation, it is difficult to achieve precise control. In addition, the patent does not relate to a method for real-time optimization of the air knife pressure, and the patent is not applicable to automatic control of differential thickness plating. The chinese patent publication No. cn106637026.a, "a method and system for controlling the real-time optimization of air knife pressure during galvanization", is also a control mode only applicable to the constant-thickness plating layer, and it adopts neural network to predict the plating layer in real time, and uses the difference between the predicted value and the measured value of the plating layer at the previous and subsequent moments as the basis for adjusting the model.
In summary, none of the existing plating thickness control methods relates to an automatic control method for differential thick plating products, and the control means adopts either a neural network prediction method or a least square method to describe the relationship between the control variables and the target values of the uniform thick plating products, so that the control conditions of the target values have large hysteresis in the whole process of unit production.
Disclosure of Invention
The invention aims to solve the technical problems that: provides an automatic real-time control method of a zinc layer for differential thick coating strip steel based on air knife pressure.
In order to solve the technical problems, the technical scheme provided by the invention is as follows: a zinc layer control method for differential thickness coating strip steel comprises the following steps:
step one, preparing data
Collecting field high-frequency data at a time interval of a control cycle under the condition of a production steady state, wherein the field high-frequency data at the time t comprises air knife pressure P1(t) of the upper surface of the strip steel, air knife pressure P2(t) of the upper surface of the strip steel, air knife distance D1 (t) of the upper surface of the strip steel, air knife distance D2 (t) of the lower surface of the strip steel, unit speed V (t), target value Zt (t) of the coating thickness of the upper surface of the strip steel, target value Zb (t) of the coating thickness of the lower surface of the strip steel, measured value ZTa (t) of the coating thickness of the upper surface of the strip steel and measured value Zba (t) of the coating thickness of the lower surface of the strip steel;
step two, judging the control mode
When the welding seam of the strip steel passes through a zinc pot, judging whether the specifications of the plating layers before and after the welding seam of the strip steel are transited or not by using the field high-frequency data of the latest two control periods t and t-1 according to the following formula:
y(t)=(Zt(t)-Zt(t-1))+(Zb(t)-Zb(t-1))；
if y (t) =0, then a transition occurs, and the flag is same _ zn =0, otherwise, no transition occurs, and the flag is same _ zn = 1;
then judging whether the target coatings on the upper surface and the lower surface of the strip steel are equal in thickness or different in thickness according to the following formula,
f(t)=Zt(t)-Zb(t)；
if f (t) =0, the target coatings on the upper surface and the lower surface of the strip steel are equal in thickness, and the control of the equal-thickness zinc layer is executed; if f (t) ≠ 0, indicating that the target coating thickness difference of the upper surface and the lower surface of the strip steel is thick, if same _ zn =0, executing a third step of pre-calculating the pressure under the thickness difference control mode, and if same _ zn =1, executing a fourth step of fine-tuning control of the air knife pressure;
step three, pre-calculating the pressure under the differential thickness control mode
Pre-calculating the pressure set value PT of the upper surface of the strip steel after the plating specification is transited according to the following formula,
Zt(t)+Za=eA0*PTA1*V(t)A2*D1(t)A3
wherein Za is the gain of the thickness of the coating on the upper surface of the strip steel, eA0For a predetermined environmental impactThe factor coefficient, A1 is a preset pressure adaptive coefficient, A2 is a preset speed adaptive coefficient, and A3 is a preset single-side distance adaptive coefficient;
pre-calculating the pressure set value PB of the lower surface of the strip steel after the plating specification is transited according to the following formula,
Zb(t)+Zb=eA0*PBA1*V(t)A2*D2(t)A3
wherein Zb is the gain of the thickness of the coating on the lower surface of the strip steel, eA0The coefficient is a preset environmental influence factor coefficient, A1 is a preset pressure adaptation coefficient, A2 is a preset speed adaptation coefficient, and A3 is a preset single-sided distance adaptation coefficient;
taking the pressure set value PT of the upper surface of the strip steel as the adjusted air knife pressure P1(t +1) of the upper surface of the strip steel, taking the pressure set value PB of the lower surface of the strip steel as the adjusted air knife pressure P2(t +1) of the lower surface of the strip steel, and then executing the step five;
step four, fine adjustment of air knife pressure of the upper surface and the lower surface of the strip steel
The air knife pressure on the upper surface of the strip steel was fine-tuned according to the following formula:
P1(t+1)=P1(t)+a1*（Zta（t）-Zt（t））+b
in the formula, a1 is a preset pressure adjustment coefficient, and b is a preset adjustment quantity;
the air knife pressure of the lower surface of the strip steel is finely adjusted according to the following formula:
P2(t+1)=P2(t)+a2*（Zba(t)-Zb（t））+b
in the formula, a2 is a preset pressure adjusting coefficient, and b is a preset regulating quantity;
and step five, performing coating thickness control by using the adjusted air knife pressure of the upper surface and the lower surface of the strip steel, and then returning to execute the step one.
The invention adopts the pre-calculation function of the pressure of the upper surface and the lower surface and the fine adjustment function of the pressure to respectively control, ensures that the coatings are controlled in respective target ranges, can solve the problem of automatic control of products with different coatings, ensures the stable operation of production, and reduces the manual intervention rate, thereby reducing the consumption of zinc raw materials, reducing the production cost and improving the surface quality of the products.
The invention can quickly control products with different specifications, adjust the pressure of the air knife with larger adjusting amplitude, and has smaller fluctuation for the products with the same specification. Therefore, the invention has larger real-time performance on the target value control condition in the whole process of unit production, the quality fluctuation of the produced product is small, and omission or large-area quality objection is not easy to occur.
Detailed Description
Examples
In this example, a continuous hot-dip galvanizing line is used as an example, a German FOEN air knife is used to position a household electric board, and the thickness of the coating is in the range of 40-140g/m2Differential thickness coating 70/50g/m2The strip steel speed is 135 m/min.
In order to perform the control calculation, the coefficients of the algorithm formula need to be formulated first. At 70/50g/m2 For example, the pressure pre-calculation coefficient of the differential thick coating can be obtained through experience, and certainly can be obtained through single-side data regression calculation after a large amount of control data under a steady state are collected, so that the problem of accurate control of the differential thick coating can be effectively solved. Table 1 below is 50g/m2 And 70g/m2 The product has coefficients of A0, A1, A2 and A3 which return under different working conditions.
TABLE 1
Coating thickness range Speed of rotation Distance of single-sided air knife A0 A1 A2 A3
40~75 60.00 10.00 0.71 -0.64 0.79 0.77
40~75 80.00 10.00 1.42 -0.48 0.63 0.58
40~75 100.00 10.00 1.45 -0.63 0.71 0.59
40~75 120.00 10.00 0.21 -0.47 0.73 0.85
40~75 140.00 10.00 0.21 -0.47 0.73 0.85
40~75 60.00 12.00 0.71 -0.64 0.79 0.77
40~75 80.00 12.00 1.42 -0.48 0.63 0.58
40~75 100.00 12.00 1.45 -0.63 0.71 0.59
40~75 120.00 12.00 0.21 -0.47 0.73 0.85
40~75 140.00 12.00 0.21 -0.47 0.73 0.85
40~75 60.00 14.00 0.71 -0.64 0.79 0.77
40~75 80.00 14.00 1.42 -0.48 0.63 0.58
40~75 100.00 14.00 1.45 -0.63 0.71 0.59
40~75 120.00 14.00 0.21 -0.47 0.73 0.85
40~75 140.00 14.00 0.21 -0.47 0.73 0.85
40~75 60.00 16.00 0.71 -0.64 0.79 0.77
40~75 80.00 16.00 1.42 -0.48 0.63 0.58
40~75 100.00 16.00 1.45 -0.63 0.71 0.59
40~75 120.00 16.00 0.21 -0.47 0.73 0.85
40~75 140.00 16.00 0.21 -0.47 0.73 0.85
40~75 60.00 18.00 0.71 -0.64 0.79 0.77
40~75 80.00 18.00 1.42 -0.48 0.63 0.58
40~75 100.00 18.00 1.45 -0.63 0.71 0.59
40~75 120.00 18.00 0.21 -0.47 0.73 0.85
40~75 60.00 8.00 0.21 -0.72 1.02 0.66
40~75 140.00 18.00 0.21 -0.47 0.73 0.85
40~75 60.00 20.00 0.71 -0.64 0.79 0.77
40~75 80.00 20.00 1.42 -0.48 0.63 0.58
40~75 100.00 20.00 1.45 -0.63 0.71 0.59
40~75 120.00 20.00 0.21 -0.47 0.73 0.85
40~75 140.00 20.00 0.21 -0.47 0.73 0.85
It should be noted that the data in table 1 are not fixed and can be readjusted according to the requirements of the strip steel and the production process, which is the prior art and will not be described again.
The zinc layer control method for the strip steel with the differential thickness coating comprises the following steps:
step one, preparing data
Collecting field high-frequency data at a time interval of a control cycle under the condition of a production steady state, wherein the field high-frequency data at the time t comprises air knife pressure P1(t) of the upper surface of the strip steel, air knife pressure P2(t) of the upper surface of the strip steel, air knife distance D1 (t) of the upper surface of the strip steel, air knife distance D2 (t) of the lower surface of the strip steel, unit speed V (t), target value Zt (t) of the coating thickness of the upper surface of the strip steel, target value Zb (t) of the coating thickness of the lower surface of the strip steel, measured value ZTa (t) of the coating thickness of the upper surface of the strip steel and measured value Zba (t) of the coating thickness of the lower surface of the strip steel.
For example, at time t, the high frequency data is: air knife pressure P1(t) =393.2 on the upper surface of the strip steel, air knife pressure P2(t) =393.6 on the lower surface of the strip steel, air knife distance D1 (t) =8.5 on the upper surface of the strip steel, air knife distance D2 (t) =8.5 on the lower surface of the strip steel, unit speed V (t) =115, target value Zt (t) =42 of coating thickness on the upper surface of the strip steel, target value Zb (t) =42 of coating thickness on the lower surface of the strip steel, measured value ZTa (t) =42.7 of coating thickness on the upper surface of the strip steel, measured value Zba (t) =42.5 of coating thickness on the lower surface of the strip steel, and used as the basis of the next calculation.
Step two, judging the control mode
When the welding seam of the strip steel passes through a zinc pot, judging whether the specifications of the plating layers before and after the welding seam of the strip steel are transited or not by using the field high-frequency data of the latest two control periods t and t-1 according to the following formula:
y(t)=(Zt(t)-Zt(t-1))+(Zb(t)-Zb(t-1))；
if y (t) =0, it indicates that transition occurs, and the flag same _ zn =0, otherwise, it indicates that transition does not occur, and the flag same _ zn = 1.
Then judging whether the target coatings on the upper surface and the lower surface of the strip steel are equal in thickness or different in thickness according to the following formula,
f(t)=Zt(t)-Zb(t)；
if f (t) =0, the target coatings on the upper surface and the lower surface of the strip steel are equal in thickness, and the equal-thickness zinc layer control is executed, and the equal-thickness zinc layer control is the prior art, and related technical documents can be referred for, and are not described again; if f (t) ≠ 0, the target coating thickness difference of the upper surface and the lower surface of the strip steel is described, if same _ zn =0 at the time, the pressure under the thickness difference control mode is pre-calculated in the third step, and if same _ zn =1 at the time, the air knife pressure is finely controlled in the fourth step.
In this example, since the target plating thickness at the last two times (t, t-1) was (70/50, 42/42), the result of y (t) is not equal to 0, and the same is set to same "same _ zn = 0" when transition between the plating specifications before and after the plating is described.
Then, the formula f (t) = Zt (t) — Zb (t) is used for calculation, whether the target coating on the upper surface and the lower surface of the steel coil is equal in thickness or different in thickness is judged, and the result f (t) ≠ 0, namely the different-thickness coating is obtained; at this time, f (t) ≠ 0 and same _ zn =0, so as to execute the third step, start the pre-calculation of the differential thickness control, and thus, control of products with different specifications can be rapidly carried out; if the same _ zn =1 and f (t) ≠ 0, entering step 4 to start fine adjustment calculation control, so considering that the fluctuation of products with the same specification is small, only fine adjustment is needed, and stable and smooth production can be kept.
After a period of production, the control enters a stable state, and if the fact that same _ zn =1 and f (t) ≠ 0 is checked again, the fine-tuning calculation function is started, and the step four is executed.
Step three, pre-calculating the pressure under the differential thickness control mode
Pre-calculating the pressure set value PT of the upper surface of the strip steel after the plating specification is transited according to the following formula,
Zt(t)+Za=eA0*PTA1*V(t)A2*D1(t)A3
wherein Za is the gain of the thickness of the coating on the upper surface of the strip steel, eA0For a preset environmental impact factor coefficient, a1 is a preset pressure adaptation coefficient, a2 is a preset speed adaptation coefficient, and A3 is a preset single-side distance adaptation coefficient;
pre-calculating the pressure set value PB of the lower surface of the strip steel after the transition of the coating specification according to the following formula,
Zb(t)+Zb=eA0*PBA1*V(t)A2*D2(t)A3
wherein Zb is the gain of the thickness of the coating on the lower surface of the strip steel, eA0For a predetermined environmental impact factor coefficient, A1 is a predetermined pressureThe adaptive coefficient A2 is a preset speed adaptive coefficient, and A3 is a preset single-side distance adaptive coefficient.
In this example, f (t) ≠ 0 and same _ zn =0, so that the differential thickness control precalculation function is started, and control adjustment can be performed with a large adjustment range, which mainly depends on a control calculation formula of the thickness of the hot galvanizing zinc layer with nonlinear and strong coupling characteristics, when calculating the pressure of the target plating layer of 70 (upper surface), according to the current speed V =115 and the distance D of 11 (process empirical value), table lookup 1 obtains a0=0.21, a1= -0.47, a2=0.73 and A3=0.85, then the calculated pressure of 70 surfaces is: 70= e0.21*PT-0.47*1150.73*110.85Calculating to obtain a pressure value of 70 surfaces PT = 251.6; similarly, when the pressure of the target plating layer is 50 (lower surface) is calculated, according to the current speed V =115 and the distance D is 9 (empirical process value), table 1 is looked up to obtain a0=0.21, a1= -0.47, a2=0.73, and A3=0.85, then the calculated pressure of the 50 surfaces is: 50= e0.21*PB-0.47*1150.73*90.85The air knife pressure of the lower surface is calculated to be PB = 313.
Taking the pressure set value PT of the upper surface of the strip steel as the adjusted air knife pressure P1(t +1) of the upper surface of the strip steel, taking the pressure set value PB of the lower surface of the strip steel as the adjusted air knife pressure P2(t +1) of the lower surface of the strip steel, and then executing the step five; .
Step four, fine adjustment of air knife pressure of the upper surface and the lower surface of the strip steel
The air knife pressure on the upper surface of the strip steel was fine-tuned according to the following formula:
P1(t+1)=P1(t)+a1*（Zta（t）-Zt（t））+b
in the formula, a1 is a preset pressure adjustment coefficient, and b is a preset adjustment quantity;
the air knife pressure of the lower surface of the strip steel is finely adjusted according to the following formula:
P2(t+1)=P2(t)+a2*（Zba（t）-Zb（t））+b
in the formula, a2 is a preset pressure adjustment coefficient, and b is a preset adjustment quantity;
the field high frequency data collected at this time are as follows: at time t, the air knife pressure P1(t) =296.1 on the upper surface of the strip steel, the air knife pressure P2(t) =389.8 on the lower surface of the strip steel, the air knife distance D1 (t) =11 on the upper surface of the strip steel, the air knife lower surface distance D2 (t) =9 on the lower surface of the strip steel, the unit speed v (t) =115, the target value zt of the coating thickness on the upper surface of the strip steel (t) =70, the target value zb of the coating thickness on the lower surface of the strip steel (t) =50, the actual value zta (t) =69.9 of the coating thickness on the upper surface of the strip steel, and the actual value zba (t) =50.4 of the coating thickness on the lower surface of the strip steel. In this case, the measured plating layer on the upper surface has a negative deviation from the target value, and therefore, it is necessary to adjust the deviation. The deviation amount DELT _ Z = zta (t) -zt (t) = -0.1 between the actual value and the target value, and DELT _ Z = -1 is taken for the convenience of calculation and query of an existing table. The pressure DELT _ P = P2(t +1) -P2(t) which needs to be adjusted according to the conversion of the coating deviation needs to be searched for an empirical coefficient table, as shown in the following table 2:
TABLE 2
D V DELT_Z DELT_P
11.00 60.00 10.00 500.00
11.00 60.00 20.00 400.00
11.00 60.00 30.00 300.00
11.00 60.00 40.00 290.00
11.00 60.00 50.00 285.00
11.00 60.00 60.00 280.00
11.00 60.00 70.00 275.00
11.00 60.00 80.00 270.00
11.00 60.00 90.00 265.00
11.00 60.00 100.00 260.00
11.00 60.00 110.00 255.00
11.00 60.00 120.00 250.00
11.00 60.00 130.00 245.00
11.00 60.00 140.00 240.00
11.00 60.00 150.00 235.00
11.00 75.00 10.00 500.00
11.00 75.00 20.00 400.00
11.00 75.00 30.00 300.00
11.00 75.00 40.00 290.00
11.00 75.00 50.00 285.00
11.00 75.00 60.00 280.00
11.00 75.00 70.00 275.00
11.00 75.00 80.00 270.00
11.00 75.00 90.00 265.00
11.00 75.00 100.00 260.00
11.00 75.00 110.00 255.00
11.00 75.00 120.00 250.00
11.00 75.00 130.00 245.00
11.00 75.00 140.00 240.00
11.00 75.00 150.00 235.00
11.00 90.00 10.00 500.00
11.00 90.00 20.00 400.00
11.00 90.00 30.00 300.00
11.00 90.00 40.00 290.00
11.00 90.00 50.00 285.00
11.00 90.00 60.00 280.00
Note: for ease of calculation and display, the values of DELT _ Z in Table 2 are 10 times the actual values and DELT _ P is 1000 times the actual values.
Since DELT _ Z = -1, the deviation amount of the coating has negative deviation, the negative deviation can cause quality failure, the process requires that the negative deviation is not allowed to occur, the pressure is adjusted at the moment, but the absolute value of the deviation amount of the coating is 1, if the deviation amount is less than the minimum deviation amount in the table 2, the adjustment is carried out according to the minimum deviation amount, so that DELT _ Z = -10 is taken, and the table lookup is carried out according to the absolute value to obtain DELT _ P = 500. Since the values in the table are multiplied by 1000 based on empirical values, the actual delt _ P =0.5, and since the deviation is negative, the final pressure set point P1(t +1) =296.1-0.5= 295.6.
And the lower surface coating deviation DELT _ Z = Zba (t) -Zb (t) =51.4-50=0.4, multiplied by 10 times 4, and compared with the corresponding values in the table 2, the deviation is found to be within the allowable tolerance (4 < 10), so that the air knife pressure of the lower surface of the strip steel is kept unchanged, namely P2(t +1) = 389.8.
Through the calculation, the pressure value which is finally issued is as follows: p1(t +1) =295.6, P2(t +1) = 389.8.
And step five, performing coating thickness control by using the adjusted air knife pressure of the upper surface and the lower surface of the strip steel, and then returning to execute the step one. So far, the complete calculation process of one differential thick coating is basically finished, and the calculation methods of other differential thick coatings are consistent with the specification calculation process and are not described again.
In the second step, if the difference between V (t) and V (t-1) exceeds the predetermined threshold when the same _ zn =1, then the third step is executed, that is, if V (t) ≠ 115 and the speed deviation exceeds the predetermined threshold 5 in this embodiment, it is determined that the control adjustment needs to be performed with a large adjustment range, so the difference thickness control pre-calculation function of the third step is started again, instead of fine-adjusting the air knife pressure of the upper and lower surfaces of the strip steel.
The present invention is not limited to the specific technical solutions described in the above embodiments, and other embodiments may be made in the present invention in addition to the above embodiments. It will be understood by those skilled in the art that any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (2)

1. A zinc layer control method for a strip steel with a differential thickness coating layer, wherein the thickness of zinc layers on the upper surface and the lower surface of the strip steel is respectively controlled by an upper air knife and a lower air knife, and the method comprises the following steps:
step one, preparing data
Collecting field high-frequency data at a time interval of a control cycle under the condition of a production steady state, wherein the field high-frequency data at the time t comprises air knife pressure P1(t) of the upper surface of the strip steel, air knife pressure P2(t) of the upper surface of the strip steel, air knife distance D1 (t) of the upper surface of the strip steel, air knife distance D2 (t) of the lower surface of the strip steel, unit speed V (t), target value Zt (t) of the coating thickness of the upper surface of the strip steel, target value Zb (t) of the coating thickness of the lower surface of the strip steel, measured value ZTa (t) of the coating thickness of the upper surface of the strip steel and measured value Zba (t) of the coating thickness of the lower surface of the strip steel;
step two, judging the control mode
When the welding seam of the strip steel passes through a zinc pot, judging whether the specifications of the plating layers before and after the welding seam of the strip steel are transited or not by using the field high-frequency data of the latest two control periods t and t-1 according to the following formula:
y(t)=(Zt(t)-Zt(t-1))+(Zb(t)-Zb(t-1))；
if y (t) =0, the transition is generated, and the name _ zn =0, otherwise, the transition is not generated, and the name _ zn = 1;
then judging whether the target coatings on the upper surface and the lower surface of the strip steel are equal in thickness or different in thickness according to the following formula,
f(t)=Zt(t)-Zb(t)；
if f (t) =0, the target coatings on the upper surface and the lower surface of the strip steel are equal in thickness, and the control of the equal-thickness zinc layer is executed; if f (t) ≠ 0, indicating that the target coating thickness difference of the upper surface and the lower surface of the strip steel is thick, if same _ zn =0, executing a third step of pre-calculating the pressure under the thickness difference control mode, and if same _ zn =1, executing a fourth step of fine-tuning control of the air knife pressure;
step three, pre-calculating the pressure under the differential thickness control mode
Pre-calculating the pressure set value PT of the upper surface of the strip steel after the plating specification is transited according to the following formula,
Zt(t)+Za=eA0*PTA1*V(t)A2*D1(t)A3
wherein Za is the gain of the thickness of the coating on the upper surface of the strip steel, eA0The coefficient is a preset environmental influence factor coefficient, A1 is a preset pressure adaptation coefficient, A2 is a preset speed adaptation coefficient, and A3 is a preset single-sided distance adaptation coefficient;
pre-calculating the pressure set value PB of the lower surface of the strip steel after the plating specification is transited according to the following formula,
Zb(t)+Zb=eA0*PBA1*V(t)A2*D2(t)A3
wherein Zb is the gain of the thickness of the coating on the lower surface of the strip steel, eA0For the preset environmental impact factor coefficient, A1 is a preset pressure adaptation coefficient, A2 is a preset speed adaptation coefficient, and A3 is a preset speed adaptation coefficientSingle-sided distance adaptation coefficient;
taking the pressure set value PT of the upper surface of the strip steel as the adjusted air knife pressure P1(t +1) of the upper surface of the strip steel, taking the pressure set value PB of the lower surface of the strip steel as the adjusted air knife pressure P2(t +1) of the lower surface of the strip steel, and then executing the step five;
step four, fine adjustment of air knife pressure of the upper surface and the lower surface of the strip steel
The air knife pressure on the upper surface of the strip steel was fine-tuned according to the following formula:
P1(t+1)=P1(t)+a1*（Zta（t）-Zt（t））+b
in the formula, a1 is a preset pressure adjustment coefficient, and b is a preset adjustment quantity;
the air knife pressure of the lower surface of the strip steel is finely adjusted according to the following formula:
P2(t+1)=P2(t)+a2*（Zba(t)-Zb（t））+b
in the formula, a2 is a preset pressure adjustment coefficient, and b is a preset adjustment quantity;
and step five, performing coating thickness control by using the adjusted air knife pressure of the upper surface and the lower surface of the strip steel, and then returning to execute the step one.
2. The method for controlling a zinc layer of a differential thickness coated steel strip as claimed in claim 1, wherein: in the second step, if the difference between V (t) and V (t-1) exceeds a predetermined threshold when same _ zn =1, the third step is executed.
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Publication number Priority date Publication date Assignee Title
CN103510032A (en) * 2012-06-20 2014-01-15 鞍钢股份有限公司 Deviation value control method for cold rolling hot galvanizing coating uniformity
CN103695830A (en) * 2013-12-20 2014-04-02 鞍钢股份有限公司 Coating thickness control method in hot galvanizing production process
CN105525248A (en) * 2015-11-30 2016-04-27 浙江中控研究院有限公司 Method for plating thickness feedforward optimal control of galvanization production line
CN108546897A (en) * 2018-05-11 2018-09-18 鞍钢股份有限公司 A kind of cold rolling hot dip galvanizing steel plate transverse direction coating uniformity control method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103510032A (en) * 2012-06-20 2014-01-15 鞍钢股份有限公司 Deviation value control method for cold rolling hot galvanizing coating uniformity
CN103695830A (en) * 2013-12-20 2014-04-02 鞍钢股份有限公司 Coating thickness control method in hot galvanizing production process
CN105525248A (en) * 2015-11-30 2016-04-27 浙江中控研究院有限公司 Method for plating thickness feedforward optimal control of galvanization production line
CN108546897A (en) * 2018-05-11 2018-09-18 鞍钢股份有限公司 A kind of cold rolling hot dip galvanizing steel plate transverse direction coating uniformity control method

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