阅读说明：本技术 一种热连轧精轧带钢头部宽度防拉窄控制方法 (Method for controlling head width of hot continuous rolling finish rolling strip steel to prevent narrowing ) 是由 李家波 张健民 张智勇 于 2019-01-10 设计创作，主要内容包括：本发明揭示了一种热连轧精轧带钢头部宽度防拉窄控制方法,属于热轧带钢生产技术领域,包括以下步骤：S1、判断活套是否接触带钢；S2、根据活套套量偏差补偿上游轧机速度；S3、判断活套是否处于拉钢状态；S4、在拉钢状态下,对控制参数进行修改,使带钢快速稳定的脱离拉钢状态。首先根据活套抬套接触带钢时的实际套量,对主传动的速度进行快速补偿,然后在套量控制投入后,对可能的拉钢状态进行判断,修改相应的控制参数,使活套能够快速脱离拉钢状态。本发明通过实时干预速度附加量和主传动速度调节速率,最大程度的避免由于穿带时机架间实际套量过大或者过小造成的带钢拉窄现象。(The invention discloses a method for controlling the head width of hot continuous rolling finish rolling strip steel to prevent narrowing, which belongs to the technical field of hot rolling strip steel production and comprises the following steps: s1, judging whether the loop contacts the strip steel or not; s2, compensating the speed of the upstream rolling mill according to the deviation of the loop quantity; s3, judging whether the loop is in a steel pulling state; and S4, modifying the control parameters under the steel drawing state to ensure that the strip steel is quickly and stably separated from the steel drawing state. Firstly, the speed of a main transmission is quickly compensated according to the actual sleeve quantity when the loop is lifted and contacted with the strip steel, then after the sleeve quantity is controlled, the possible steel pulling state is judged, and the corresponding control parameters are modified, so that the loop can be quickly separated from the steel pulling state. The invention intervenes the speed addition quantity and the main transmission speed regulation rate in real time, and avoids the phenomenon of strip steel narrowing caused by overlarge or undersize actual sleeve quantity between frames during threading to the maximum extent.)

1. A method for controlling the width of the head of hot continuous rolling finish rolling strip steel to prevent narrowing is characterized by comprising the following steps: the method comprises the following steps:

s1, judging whether the loop contacts the strip steel or not, after the downstream rack bites the steel, quickly lifting the loop with a certain torque until the loop contacts the strip steel, and judging the condition that the loop contacts the strip steel as follows: omega_act＜γ·ω_max，

In the formula, ω_actIs the actual angular velocity, omega, of the loop_maxThe maximum angular speed of the loop during the loop lifting period is shown, and gamma is a coefficient for judging the contact of the loop with the strip steel;

s2, compensating the speed V of the upstream rolling mill according to the deviation of the loop amount_addAccording to the loop quantity deviation L when the loop contacts the strip steel within 1s of the opening control of the loop_devCalculating to obtain V_add，

L_dev＝L_aim-L_touch

In the formula, L_aimTarget loop quantity for loop L_touchThe actual sleeve amount V when the loop contacts the strip steel_touchThe speed, V, of the upstream frame when the loop contacts the strip_maxFor maximum process speed, V, during threading of an upstream stand_PLIAccording to the sleeve amount deviation L_devSpeed compensation quantity obtained by segmented interpolation;

s3, judging whether the loop is in a steel pulling state or not, and controlling the opening T of the loop_sAnd in time, when the following conditions are met, the loop is considered to be in a steel drawing state:

in the formula, ω_actFor actual rate of change of the sleeve quantity, omega_JudgeThe change speed of the loop quantity is a judgment standard when the loop is in a steel drawing state, and a value is taken according to the response performance of an actual loop system, L_dev1＝L_aim-L_actL deviation between target and actual loop amount_JudgeThe sleeve quantity deviation judgment standard is used for judging that the loop is in a steel drawing state;

s4, modifying the control parameters in the steel drawing state to make the strip steel quickly and stably break away from the steel drawing state, and aiming at the loop cover quantity deviation, the controller for compensating the main transmission speed of the upstream frame is as follows:

in the formula, Y_nThe corrected value of the upstream frame main transmission speed is output at the sampling time n, Y_n-1For the output of the speed correction value at the sampling time n-1, Kp is the total gain of PI control, TA is the sampling period, Tn is the integration time constant, YE_nSet quantity deviation, YE, for sampling time n_n-1For the set quantity offset at sample time n-1, β is a coefficient.

2. The method for controlling the head width of the hot continuous rolling finish rolling strip steel as claimed in claim 1, wherein the value of γ in the step S1 is in the range of 0.5 to 0.9.

3. The hot continuous rolling finish rolling strip steel head width anti-narrowing control method of claim 1, wherein the step S3 is to control the opened T of the loop_sThe steel drawing of the head of the strip steel is within 10s of steel biting, T_sThe value is within 10 s-30 s.

4. The hot continuous rolling finish rolling strip steel head width anti-narrowing control method of claim 3, wherein the L of the step S3_JudgeThe value of the sleeve quantity deviation judgment standard for judging that the loop is in a steel drawing state is 1-2 mm; in order to prevent the condition misjudgment from causing the loop to frequently enter and exit the steel drawing state, the time delay judgment is carried out on the basis of the condition, namely the state lasts for t_cAbove the time, the loop is considered to be in a steel-drawing state.

5. The hot continuous rolling finish rolling strip steel head width anti-narrowing control method according to claim 4, characterized in that the delay time t_cThe value range of (A) is 100 ms-1000 ms.

6. The method for controlling the head width of the hot continuous rolling finish rolling strip steel to prevent the head width from being narrowed according to claim 1, wherein the value of β in the step S4 is in the range of 0.1-1, and when the strip steel is out of a steel-drawing state, the value of β is immediately restored to 1.

Technical Field

The invention relates to the technical field of hot-rolled strip steel production, in particular to a method for controlling the width of the head of hot continuous rolling finish rolling strip steel to prevent narrowing.

Background

In the process of hot continuous rolling finish rolling control, threading is an important and difficult-to-control link, and severe tension fluctuation is easy to occur in a period from steel biting to stable loop control investment, so that the head of the strip steel is narrowed, and a tandem rolling scrap steel accident is seriously caused. The premise that the loop can be quickly and stably controlled during threading is that the metal second flow difference between frames is maintained within a certain range, but the loop is easily over-large or over-small in the threading process due to the influence of a plurality of factors such as the initial roll gap and speed setting of a process machine, the impact speed reduction of main transmission in the steel biting process, the state of rolling equipment and the like, so that the head of the strip steel is narrowed, and the waste time reduction of hot rolled products is increased.

The patent publication No. CN104801548B, by learning the manual intervention amount of the operator to the speed, corrects the speed set value of the next steel with the same specification, and achieves the purposes of improving the threading and reducing the width narrowing; patent publication No. CN104874613A, through to this belted steel threading in-process, the study of loop speed adjustment volume, revise next belted steel of the same specification, reach the phenomenon that the width reduces and draws narrowly. The above patent mainly performs speed preset optimization on the next steel through learning based on the related correction of the steel, so as to gradually improve the initial threading condition, but cannot cope with the temporary sudden change condition.

KR780423B1 is through calculating the tension value of the back frame after stinging the steel strip, modifies the moment coefficient of loop to reach the purpose that improves belted steel head width quality, avoids drawing the narrow. The scheme is mainly based on a tension calculation value after steel biting, and is difficult to calculate accurately in an unstable state. The patent publication No. CN103464472 dynamically sets the tension value of the strip steel according to the temperature of the strip steel, thereby solving the problem that the width of the strip steel is narrowed along with the temperature rise; the scheme mainly solves the problem that the temperature change influences the width of the strip steel, but the temperature of the head of the strip steel is difficult to predict accurately, and the control effect is influenced.

Disclosure of Invention

Technical problem to be solved

Aiming at the defect that the head of the strip steel is easy to be narrowed in the strip threading process of the steel, the invention provides a control method for preventing the head of the hot continuous rolling finish rolling strip steel from being narrowed, which intervenes in real time the speed addition quantity and the main transmission speed regulation rate on the basis of the traditional loop starting control, and avoids the strip steel narrowing phenomenon caused by the fact that the actual loop quantity between racks is too large or too small during the strip threading to the maximum extent.

(II) technical scheme

A method for controlling the head width of hot continuous rolling finish rolling strip steel to prevent narrowing comprises the following steps:

s1, judging whether the loop contacts the strip steel or not, after the downstream rack bites the steel, quickly lifting the loop with a certain torque until the loop contacts the strip steel, and judging the condition that the loop contacts the strip steel as follows: omega_act＜γ·ω_max，

In the formula, ω_actIs the actual angular velocity, omega, of the loop_maxThe maximum angular speed of the loop during the loop lifting period is shown, and gamma is a coefficient for judging the contact of the loop with the strip steel;

s2, compensating the speed V of the upstream rolling mill according to the deviation of the loop amount_addAccording to the loop quantity deviation L when the loop contacts the strip steel within 1s of the opening control of the loop_devCalculating to obtain V_add，

L_dev＝L_aim-L_touch

In the formula, L_aimTarget loop quantity for loop L_touchThe actual sleeve amount V when the loop contacts the strip steel_touchThe speed, V, of the upstream frame when the loop contacts the strip_maxFor maximum process speed, V, during threading of an upstream stand_PLIAccording to the sleeve amount deviation L_devSpeed compensation quantity obtained by segmented interpolation;

s3, judging whether the loop is in a steel pulling state or not, and controlling the opening T of the loop_sAnd in time, when the following conditions are met, the loop is considered to be in a steel drawing state:

in the formula, ω_actFor actual rate of change of the sleeve quantity, omega_JudgeThe change speed of the loop quantity is a judgment standard when the loop is in a steel drawing state according to the actual loopResponse performance value of the system, L_dev1＝L_aim-L_actL deviation between target and actual loop amount_JudgeThe sleeve quantity deviation judgment standard is used for judging that the loop is in a steel drawing state;

s4, modifying the control parameters in the steel drawing state to make the strip steel quickly and stably break away from the steel drawing state, and aiming at the loop cover quantity deviation, the controller for compensating the main transmission speed of the upstream frame is as follows:

in the formula, Y_nThe corrected value of the upstream frame main transmission speed is output at the sampling time n, Y_n-1For the output of the speed correction value at the sampling time n-1, Kp is the total gain of PI control, TA is the sampling period, Tn is the integration time constant, YE_nSet quantity deviation, YE, for sampling time n_n-1For the set quantity offset at sample time n-1, β is a coefficient.

According to an embodiment of the invention, the value range of γ in the step S1 is 0.5 to 0.9.

According to an embodiment of the present invention, the step S3 is performed at T when the loop control is opened_sThe steel drawing of the head of the strip steel is within 10s of steel biting, T_sThe value is within 10 s-30 s.

According to an embodiment of the present invention, L of the step S3_JudgeThe value of the sleeve quantity deviation judgment standard for judging that the loop is in a steel drawing state is 1-2 mm; in order to prevent the condition misjudgment from causing the loop to frequently enter and exit the steel drawing state, the time delay judgment is carried out on the basis of the condition, namely the state lasts for t_cAbove the time, the loop is considered to be in a steel-drawing state.

According to an embodiment of the present invention, the delay time t_cThe value range of (A) is 100 ms-1000 ms.

According to an embodiment of the invention, the value range of β in the step S4 is 0.1-1, and when the strip steel is separated from the steel-drawing state, the value of β is immediately restored to 1

(III) advantageous effects

By adopting the technical scheme of the invention, the method for controlling the head width of the hot continuous rolling finish rolling strip steel to prevent the narrowing of the strip steel head comprises the steps of firstly quickly compensating the speed of a main transmission according to the actual sleeve quantity when a loop is lifted and contacted with the strip steel, then judging the possible steel drawing state after the sleeve quantity is controlled, and modifying corresponding control parameters to ensure that the loop can be quickly separated from the steel drawing state; the invention intervenes the speed addition quantity and the main transmission speed regulation rate in real time, and avoids the phenomenon of strip steel narrowing caused by overlarge or undersize actual sleeve quantity between frames during threading to the maximum extent.

Drawings

In the present invention, like reference numerals refer to like features throughout, wherein:

fig. 1 is a schematic structural view of a conventional finish rolling loop system for hot continuous rolling.

FIG. 2 is a flow chart of the method of the present invention.

FIG. 3 is a graph of deviation between a target value and an actual value of a strip width according to an embodiment.

FIG. 4 is a graph showing the deviation between the target value and the measured value of the width of the strip steel according to the second embodiment.

Detailed Description

The technical scheme of the invention is further explained by combining the drawings and the embodiment.

A control method for preventing the width of strip steel from being narrowed in the process of hot continuous rolling finish rolling threading comprises the steps of firstly, carrying out interpolation compensation on the speed of main transmission in time according to the actual sleeve quantity when a loop is lifted and contacts the strip steel; and then after the sleeve amount is controlled to be input, the possible steel drawing state is evaluated, and corresponding control parameters are modified, so that the loop can be quickly separated from the steel drawing state, and the size class blockage caused by the narrowing of the strip steel is prevented to the greatest extent.

As shown in figure 1, a traditional hot continuous rolling finish rolling area consists of seven racks (1-7 in the figure), and in order to ensure that a plate blank stably passes through a belt, rolls and throws steel in the finish rolling area, a loop system (11-16 in the figure) is arranged among the racks and used for controlling the condition that the loop quantity is too large or too small due to mismatching of strip steel flow among the racks. The situation is very easy to occur in the threading process, the sleeve amount is too small, and the strip steel is very easy to narrow; the excessive sleeve amount easily causes control overshoot, and the situation of the excessive sleeve amount also occurs, so that the strip steel is narrowed; in addition, even if the threading is stable, the roll gaps of the frames need to be adjusted to ensure the outlet thickness, and large interference can be caused to the sleeve amount between the frames.

With reference to the flow chart 2, the method for controlling the width of the head of the hot continuous rolling finish rolling strip steel to prevent the strip steel from being narrowed is applied to each loop and comprises the following steps:

and S1, judging whether the loop contacts the strip steel. After the downstream machine frame bites the steel, the loop is lifted up rapidly with a certain torque until contacting the strip steel, and the condition that the loop contacts the strip steel is judged as follows: omega_act＜γ·ω_max，

In the formula, ω_actIs the actual angular velocity, omega, of the loop_maxThe maximum angular speed of the loop during the loop lifting period is shown, and gamma is a coefficient for judging the contact of the loop with the strip steel; the value range of gamma is 0.5-0.9.

S2, compensating the speed V of the upstream rolling mill according to the deviation of the loop amount_addAccording to the loop quantity deviation L when the loop contacts the strip steel within 1s of the opening control of the loop_devCalculating to obtain V_addThe specific calculation method is as follows:

L_dev＝L_aim-L_touch

in the formula, L_aimTarget loop quantity for loop L_touchThe actual sleeve amount V when the loop contacts the strip steel_touchThe speed, V, of the upstream frame when the loop contacts the strip_maxFor maximum process speed, V, during threading of an upstream stand_PLIAccording to the sleeve amount deviation L_devThe interpolation method of the speed compensation quantity obtained by piecewise interpolation is shown as the following table:

TABLE 1V_PLISegmented interpolation table

Ldev(m)	VPLI(m/s)
		-0.001	0
0	0
		0.001	0.03
0.002	0.06
		0.003	0.1
0.004	0.14
		0.005	0.16
0.006	0.18
		0.007	0.18

Because the scheme mainly compensates the width narrowing phenomenon caused by the low initial sleeve amount of the loop, the speed of the upstream rack is not compensated under the condition that the actual sleeve amount is larger than the target sleeve amount. Because the maximum sleeve amount between the frames is about 0.007m, interpolation is carried out by using a first gear of 0.001m, and each loop V_PLIMay be directed toEach loop was obtained empirically as shown in table 1. Of course, the upstream frame speed compensation value can be calculated more accurately according to the sleeve quantity deviation, the speed response capability of the upstream frame, the expected lifting time of the loop and the like.

S3, judging whether the loop is in a steel pulling state or not, and controlling the opening T of the loop_s(it is generally accepted that strip head pull occurs within 10s of bite, where T_sThe value is 10 s-30 s) according to experience, and the loop is considered to be in a steel drawing state when the following conditions are met:

in the formula, ω_actFor actual rate of change of the sleeve quantity, omega_JudgeThe change speed of the loop quantity when the loop is in a steel drawing state can be judged according to the response performance value of an actual loop system, L_dev1＝L_aim-L_actL deviation between target and actual loop amount_JudgeThe sleeve quantity deviation judgment standard for judging the loop in the steel drawing state generally takes a value of more than 1-2 mm. In order to prevent the condition misjudgment, which causes the loop to frequently enter and exit the steel drawing state, the time delay judgment needs to be carried out on the basis of the condition, namely the state lasts for t_cAbove the time, the loop is considered to be in a steel-drawing state. t is t_cThe value range of (A) is 100 ms-1000 ms.

S4, modifying the control parameters in the steel drawing state to make the strip steel quickly and stably break away from the steel drawing state, and aiming at the loop cover quantity deviation, the controller for compensating the main transmission speed of the upstream frame is as follows:

in the formula, Y_nThe corrected value of the upstream frame main transmission speed is output at the sampling time n, Y_n-1For the output of the speed correction value at the sampling time n-1, Kp is the total gain of PI control, TA is the sampling period, Tn is the integration time constant, YE_nSet quantity deviation, YE, for sampling time n_n-1The fitting quantity deviation is the fitting quantity deviation of the sampling time n-1, β is a coefficient, the value range is 0.1-1, and when the strip steel is separated from the steel drawing state, the value β is immediately restored to 1.

In a traditional loop control system, aiming at loop quantity deviation, a controller for compensating the main transmission speed of an upstream rack is as follows:

the method is applicable to a loop system, particularly an electric loop system, when the loop system is in a low-position steel drawing state, the adjusting speed of a controller is not fast enough, and the steel strip is easy to narrow, so that the situation is improved, when the steel strip is in the steel drawing state, the Tn value is directly reduced to β Tn, the β value range is 0.1-1, and when the steel strip is separated from the steel drawing state, the β value is immediately restored to 1, so that the steel strip cannot be narrowed, and the system cannot be influenced by overlarge impact.