WO2023173673A1

WO2023173673A1 - Control method for automatically adjusting inlet and outlet speeds of cold rolling production line

Info

Publication number: WO2023173673A1
Application number: PCT/CN2022/112407
Authority: WO
Inventors: 宋军
Original assignee: 中冶南方工程技术有限公司
Priority date: 2022-03-18
Filing date: 2022-08-15
Publication date: 2023-09-21
Also published as: CN114749491B; CN114749491A

Abstract

A control method for automatically adjusting the inlet and outlet speeds of a cold rolling production line, comprising: first, converting a looper position into a strip steel position in a loop, then calculating in advance an acceleration fillet time compensation value and an acceleration direction change compensation value of the actual strip steel position; using a speed difference of the inlet and outlet of the loop as a positioning speed, optimizing a square root curve of the positioning speed; only monitoring a positioning starting point when the positioning speed is higher than a maximum allowable speed; calculating a set positioning speed using a positioning deviation and the positioning acceleration by means of a square root formula when the positioning deviation is in the square root curve section range; calculating the set positioning speed using the positioning deviation by means of a linearization formula when the positioning deviation is in the linearization section range; and controlling the positioning speed by means of a PI regulator when the positioning deviation is in an acceleration fillet smooth distance range. The present control method improves position control precision, ensures the smoothness and stability of inlet and outlet positioning speed, and improves production efficiency.

Description

Control method for automatic adjustment of entrance and exit speed of cold rolling production line

Technical field

The invention relates to electrical control of a cold rolling production line, and in particular to a control method for automatically adjusting the entrance and exit speed of a cold rolling production line.

Background technique

As shown in Figure 1 below, according to the needs of process production, the unit layout of the cold rolling production line generally includes the entrance section, entrance looper, process section, exit looper and exit section; in the entrance section, the unfolding and shearing of the raw material rolls are completed. and welding; in the process section, the continuous strip is completed with scale breaking, straightening, cleaning, degreasing, annealing, smoothing, rolling, coating and other processes; in the exit section, the separation of the continuous strip after process treatment is completed. Cutting and winding of finished rolls. In order to ensure the process quality of strip steel, increase unit output, and reduce energy consumption, it is generally required that the strip running speed in the process section be kept stable during the production process. Then, when the entrance section strip slows down or even stops for a short time due to tail flicking, threading, shearing, welding, etc., the strip stored in the entrance looper (5) is used to maintain the process section strip during this period of time. Stability of steel running speed. Similarly, when the quality inspection, flicking, shearing and threading of the exit section causes the strip speed in the exit section to slow down or even stop, the speed of the process section is kept stable by filling the outlet looper (8).

The vertical looper structure and looper tension/position control are shown in Figure 2. The horizontal looper is similar: the looper motor (15) drags the looper car through the looper winch (13) and the looper steel rope (21) (22) reciprocates up and down to complete the action of charging and discharging the sleeves. The lowest position of the looper car (22) is the empty sleeve position, and the sleeve volume is 0%. The highest position of the looper cart (22) is the full sleeve position, and the sleeve volume is 100. %, the effective stroke of the looper (22) is between the empty position and the full position, and the length is L.

In order to ensure the stability of the speed of the process section to the greatest extent, during the production process, the inlet looper (5) is required to keep the sleeve volume as high as possible and the outlet looper (8) to keep the sleeve volume as low as possible: when the entrance section or the outlet section slows down or stops When the state returns to normal operation, it usually accelerates quickly to a speed higher than that of the process section, filling the inlet looper (5) or releasing the outlet looper (8). When the inlet looper (5) reaches the set high volume or the outlet looper (8) reaches the set low volume, the inlet or outlet section will decelerate to the same speed as the process section to maintain the inlet and outlet loop ( 5, 8) The sleeve volume is kept close to the set value; the general approach to the above control process is to directly use a PI regulator to realize automatic adjustment of the inlet and outlet speed by controlling the sleeve volume of the looper (5, 8).

However, since the acceleration and deceleration rate of the unit for normal production has been preset according to the process requirements and cannot be changed at will, the operator may not increase the speed according to the output curve of the regulator during the inlet and outlet speed-up process, resulting in PI regulator saturation, and PI The parameters may not be able to adapt to all the set volume difference ranges, causing inlet and outlet speed oscillations during the same speed adjustment process as the process section. Therefore, using PI adjustment alone cannot meet the control requirements well. This is also the reason why the inlet and outlet of the current cold rolling production line Difficulties encountered by automatic speed adjustment.

Contents of the invention

The purpose of this invention is to provide a control method for automatic adjustment of the entrance and exit speed of a cold rolling production line. The positioning process is divided into multiple sections of control according to the position deviation range, which improves the position control accuracy, ensures the smoothness of the entrance and exit positioning speed, and is more conducive to the production process. The process optimization and equipment maintenance in the process improve the stability of speed control, increase the degree of freedom and convenience, ensure the stability of the unit, and improve production efficiency.

The technical solution adopted by the present invention is:

A control method for automatic adjustment of the entrance and exit speed of a cold rolling production line, which is realized through looper positioning. The first step is to calculate the position deviation compensation of the looper: first convert the looper car positioning into the looper inner strip positioning through conversion, and then use For the acceleration and acceleration rounding time values of the inlet and outlet sections, the acceleration rounding time compensation value and acceleration direction change compensation value of the actual strip position are pre-calculated at the moment when the inlet and outlet looper positioning is started, and are used as pre-control values for looper positioning control; The second step is to calculate the positioning speed setting value of the looper: take the speed difference between the inlet and outlet of the looper as the positioning speed, optimize the square root curve of the positioning speed, and obtain the linearization segment and the square root curve segment. In the process of the position deviation decreasing in sequence , when the positioning speed is greater than the maximum allowable speed, only the positioning start point is monitored. When the positioning deviation is within the range of the square root curve segment, the positioning set speed is calculated using the square root formula using the positioning deviation and positioning acceleration. When the positioning deviation is within the range of the linearization segment The positioning setting speed is calculated using the positioning deviation using the linearization formula. When the positioning deviation is within the acceleration rounded smoothing distance range, the positioning speed is controlled through the PI regulator.

Furthermore, when converting the positioning of the looper car into the positioning of the strip within the looper, the method is as follows: the inlet and outlet speeds V _IN and V _OUT of the looper are the strip speeds, and the sleeve volume of the looper reflects the positioning of the looper car in the empty sleeve. The position between the position and the full set position is to first uniformly convert the set amount into the length value of the strip, and then convert the set amount control into the positioning control of the strip within the looper. The calculation formula is S=C×L×N, where , S is the strip position, C is the looper setting amount %, L is the physical length of the looper, N is the number of strip steel layers in the looper, and then the set amount of the looper is the amount between the set amount of the looper and the actual amount of the looper. The deviation value is converted into the position deviation ΔS of the strip. The calculation formula is ΔS = C _setp × L × NC _act × L × N, where C _setp is the set amount of the looper %, and C _act is the actual loop amount %. .

Furthermore, when calculating the acceleration fillet time compensation value of the actual strip position, the method is: in order to obtain a smooth speed curve, the acceleration of the cold rolling production line is applied to each section of the production line through a fillet smooth curve, and T _p is the acceleration fillet. time, due to the existence of the acceleration rounding time T _p , the actual distance traveled by the entrance and exit sections of the production line during the constant speed startup for looper positioning is larger than expected. This must be taken into account in advance when calculating the actual positioning distance. The calculation formula is:

Among them, S _c1 is the acceleration fillet time compensation value of the actual positioning distance; V _IN is the looper inlet speed; V _OUT is the looper exit speed; A _setp is the positioning acceleration, which is the normal operating acceleration of the entrance section or exit section.

Furthermore, when calculating the compensation value for the acceleration direction change of the actual strip position, the method is: in order to obtain a smooth speed curve, the acceleration of the cold rolling production line is applied to each section of the production line through a rounded smooth curve, and T _p is the acceleration rounding time. , if the entrance and exit sections are accelerating and decelerating before positioning is started, and positioning control will cause the acceleration direction to change, then after positioning is started, its acceleration must first pass through the fillet curve to 0, and then accelerate and decelerate during the positioning process. In calculating the actual The positioning distance must be taken into account in advance. The calculation formula is:

Among them, S _c2 is the acceleration direction change compensation value of the actual positioning distance; V _IN is the looper inlet speed; V _OUT is the looper exit speed; A is the actual acceleration of the entrance section or exit section at the moment of positioning start; A _setp is the positioning acceleration , which is the normal operating acceleration of the entrance section or exit section; T'=A×T _p /A _setp , which is the time required for the acceleration to reach zero through the fillet curve.

Furthermore, using the speed difference between the inlet and outlet of the looper as the positioning speed, when optimizing the square root curve of the positioning speed, the method is: the position deviation between the looper positioning set value and the actual value and the positioning acceleration are used to calculate the looper positioning speed. Basically, the theoretical relationship between position, velocity and acceleration conforms to the classic square root formula. According to the square root formula, the positioning speed calculation formula is derived as

Among them, V is the positioning speed; A _setp is the positioning acceleration; ΔS is the position deviation;

When the position deviation is large, the speed curve calculated by the previous formula is relatively smooth and can meet the control requirements. However, when the position deviation is small, the speed curve calculated by the previous formula is very steep and the speed change is too drastic and cannot be directly applied;

When the position deviation is less than ΔS', the previous formula is no longer used for calculation, and the linearized formula is used instead.

Among them, a is the slope of the linearized straight line; ΔS ≤ ΔS'; ΔS' is the position deviation switching point of the two calculation formulas;

According to the characteristics of the square root curve, select the optimal switching point

The linearized formula is obtained:

Among them, T _p is the acceleration rounding time;

Shift the curve to the right by ΔS' to get the speed curve starting from zero, which is the square root curve of the optimized positioning speed. Taking into account the influence of the acceleration fillet curve of each section, the calculation formula is:

Among them, '+' is the entrance looper/'-' is the outlet looper; SIGN is the position deviation ΔS sign, 1=positive, -1=negative; S _r =A _setp ×T _p ² /6, which is the acceleration smoothing distance .

Furthermore, when the positioning speed is greater than the maximum allowable speed, only the positioning start point is monitored. The specific method is: when the position deviation ΔS is greater than a certain value, the calculated total positioning set speed will exceed the upper speed limit of the entrance section or exit section. Then when the position deviation ΔS is greater than the upper speed limit, the positioning control still calculates the positioning speed V in real time. For the entrance looper, the smaller value of the maximum speed V _INmax of the entrance section and the total positioning set speed V _OUT +V is taken as the entrance section. For speed setting, for the exit looper, take the smaller value of the maximum speed V _OUTmax of the exit section and the total positioning set speed V _IN +V as the speed setting of the exit section.

Furthermore, when the positioning deviation is within the acceleration radius smoothing distance range, the positioning speed is controlled through the PI regulator. The specific method is: when the looper deviation is extremely small, in order to obtain better control effects, a PI controller is used to control the position. control, the calculation formula is

Among them, '+' is the entrance looper/'-' is the outlet looper; V is the positioning speed; K _P is the proportional coefficient; ΔS _n is the position deviation of this cycle; T is the sampling period; T _i is the integration time.

The beneficial effects of the present invention are:

The positioning process of the strip in the looper is divided into four parts for control, which improves the positioning control accuracy of the looper. The calculated positioning speed is used as the speed limiter value of the inlet and outlet section, thus realizing the inlet and outlet speed to automatically follow the speed of the process section. Speed automatic control function;

By converting the positioning of the looper car into the positioning of the strip within the looper, the control method after the conversion is more intuitive for the control object - the inlet and outlet strip speed, and is more conducive to process optimization and equipment maintenance in the production process;

The compensation value of the actual strip position is pre-calculated at the moment when the looper positioning is started. As the pre-control value of the looper positioning control, it greatly reduces the positioning overshoot that occurs during the looper positioning process, improves the positioning control accuracy, and at the same time reduces It reduces the inlet and outlet speed adjustment amplitude caused by positioning overshoot and improves the stability of speed control;

Before the looper positioning is started, only the position of the looper is monitored in real time without interfering with the speed of the inlet and outlet. The operator can freely adjust the speed according to the unit conditions, which improves the freedom and convenience of this function;

After the positioning is started, the process acceleration of the inlet and outlet is used for deceleration positioning, which not only meets the positioning requirements but also meets the requirements of process control. At the same time, the positioning deceleration distance is minimized, ensuring the stability of the unit and improving production efficiency;

According to the position deviation range, the positioning process is divided into three stages of control, which improves the position control accuracy and ensures smooth entry and exit positioning speed.

Description of the drawings

Figure 1 is a schematic diagram of a typical unit layout of a cold rolling continuous production line.

Figure 2 is a schematic diagram of the entrance vertical looper structure and looper tension/position control.

Figure 3 is a schematic diagram of the acceleration fillet curve of each section of the cold rolling production line.

Figure 4 is a schematic diagram for calculating the acceleration fillet time compensation value in the calculation of the actual strip position of the looper positioning.

Figure 5 is a schematic diagram for calculating the compensation value of acceleration direction change in the calculation of the actual strip position of the looper positioning.

Figure 6 is a schematic diagram before and after the square root curve optimization of the looper positioning speed setting value calculation.

Figure 7 is a schematic diagram of the complete looper positioning speed setting curve taking the inlet looper as an example; area ① is the looper positioning monitoring area, area ② is the looper positioning square root curve area, and area ③ is the looper positioning linearization Area, area ④ is the looper positioning PI control area.

In the picture: 1-Uncoiler; 2-Inlet shear; 3-Welding machine; 4-Inlet looper and entrance tension roller; 5-Inlet looper; 6-Inlet looper and outlet tension roller; 7-Outlet looper and entrance tension roller ; 8-Export looper; 9-Export looper outlet tension roller; 10-Export shear; 11-Coiler; 12-Looper absolute encoder; 13-Looper winch; 14-Looper gearbox; 15 -Looper motor; 16-Looper incremental encoder; 17-Inlet tension roller incremental encoder; 18-Inlet tension roller motor; 19-Inlet tension roller gearbox; 20-Looper bottom roller; 21- Loop steel rope; 22-loop car; 23-loop tower base; 24-loop tension meter roller.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples.

A control method for automatic adjustment of the entrance and exit speed of a cold rolling production line, which is realized through looper positioning. The first step is to calculate the position deviation compensation of the looper: first convert the looper car positioning into the looper inner strip positioning through conversion, and then use For the acceleration and acceleration rounding time values of the inlet and outlet sections, the acceleration rounding time compensation value and acceleration direction change compensation value of the actual strip position are pre-calculated at the moment when the inlet and outlet looper positioning is started, and are used as pre-control values for looper positioning control; The second step is to calculate the positioning speed setting value of the looper: take the speed difference between the inlet and outlet of the looper as the positioning speed, optimize the square root curve of the positioning speed, and obtain the linearization segment and the square root curve segment. In the process of the position deviation decreasing in sequence , when the positioning speed is greater than the maximum allowable speed, only the positioning start point is monitored. When the positioning deviation is within the range of the square root curve segment, the positioning set speed is calculated using the square root formula using the positioning deviation and positioning acceleration. When the positioning deviation is within the range of the linearization segment The positioning setting speed is calculated using the positioning deviation using the linearization formula. When the positioning deviation is within the acceleration rounded smoothing distance range, the positioning speed is controlled through the PI regulator. The specific process is as follows:

1. Position deviation compensation

As shown in Figure 2 (Figure 2 is a schematic diagram of the inlet looper, the outlet looper is similar), the inlet and outlet speeds V _IN and V _OUT of the looper are the strip speed, and the sleeve volume of the looper reflects the speed of the looper car in the air. The position between the set position and the full set position. In order to facilitate the analysis, we uniformly convert the sleeve volume into the length value of the strip, and convert the sleeve volume control into the positioning control of the strip within the looper. The calculation formula is as follows:

S＝C×L×N

In the formula: S is the strip position; C is the looper volume %; L is the physical length of the loop; N is the number of strip layers in the looper.

The above formula is used to convert the set amount deviation value (%) between the set amount of the looper (%) and the actual set amount of the looper (%, calculated by the absolute encoder) into the position deviation ΔS of the strip. The calculation formula is as follows:

ΔS＝ _Csetp ×L× _NCact ×L×N

In the formula: ΔS is the position deviation; C _setp is the set amount of the looper %; C _act is the actual loop amount %; L is the physical length of the looper; N is the number of steel strip layers in the looper.

The looper positioning control is inevitably accompanied by the speed change of the entrance and exit sections. In order to obtain a smooth speed curve, the acceleration of the cold rolling production line is applied to each section of the production line through a rounded smooth curve. In Figure 3, a does not use a smooth speed curve, b uses a smooth speed curve, and T _p is the acceleration. Corner time.

1. Acceleration rounding time compensation

Due to the acceleration rounding time, the actual distance traveled by the entrance and exit section of the production line during the constant speed startup for looper positioning is larger than expected. The shaded area c in Figure 4 below is the imagined positioning distance, and the shaded area d is The actual positioning distance traveled when running according to this acceleration when there is rounding time, should be taken into account in advance when calculating the actual positioning distance. The formula for calculating the area of this part is as follows:

In the formula: S _c1 is the acceleration fillet time compensation value of the actual positioning distance; V _IN is the looper inlet speed; V _OUT is the looper exit speed; T _p is the entrance section (corresponding to the entrance looper positioning) or exit section (corresponding to The acceleration rounding time of the exit loop positioning); A _setp is the positioning acceleration, which is the normal operating acceleration of the entrance section (corresponding to the entrance loop positioning) or the exit section (corresponding to the outlet loop positioning).

2. Compensation for changes in acceleration direction

If the entrance and exit sections are accelerating and decelerating before positioning is started, and positioning control will cause the acceleration direction to change, then after positioning is started, its acceleration must first pass through the fillet curve to 0, and then accelerate and decelerate during the positioning process, as shown in Figure 5 below. As shown, the shaded area e in the figure is the positioning distance of the strip running when the acceleration passes through the fillet curve to 0 in this case. This should be taken into account in advance when calculating the actual positioning distance. The formula for calculating the area of this part is as follows:

In the formula: S _c2 is the acceleration direction change compensation value of the actual positioning distance; V _IN is the looper entrance speed; V _OUT is the looper exit speed; A is the entrance section (corresponding to the entrance looper positioning) or exit section (corresponding to the entrance looper positioning) at the moment of positioning start. corresponding to the actual acceleration of the exit loop positioning); T _p is the acceleration rounding time of the entrance section (corresponding to the entrance loop positioning) or the exit section (corresponding to the exit loop positioning); A _setp is the positioning acceleration, which is the entry section (corresponding to the exit loop positioning) The normal operating acceleration of the inlet loop positioning) or the exit section (corresponding to the outlet loop positioning); T'=A×T _p /A _setp , which is the time required for the acceleration to reach zero through the fillet curve.

2. Calculation of looper positioning speed setting value

For the inlet looper, when the speed of the process section (i.e., the outlet speed V _OUT of the inlet loop) remains stable, when the speed of the inlet section (i.e., the inlet speed V _IN of the inlet loop) is higher than V _OUT , the sleeve is filled, and when it is lower than When V _OUT , the sleeve is released, that is, the speed difference between the inlet and outlet of the looper determines the action of charging and discharging the sleeve and the rate of charging and discharging the sleeve. Split the inlet speed V _IN of the inlet loop into V _OUT + V. V is the speed difference between the inlet and outlet of the inlet loop. Then, the positioning control of the inlet loop can be realized by adjusting the inlet speed V _IN. The set of inlet and outlet speed difference V is achieved.

Similarly, for the outlet looper, the inlet speed V _IN is the speed of the process section, and the outlet speed V _OUT (=V _IN +V) is the speed of the outlet section. The positioning control of the outlet looper can be realized by adjusting the outlet section speed V _OUT . The inlet and outlet speed difference V of the outlet looper is realized.

1. Looper positioning control based on square root curve

The position deviation between the looper positioning set value and the actual value and the positioning acceleration are the basis for calculating the looper positioning speed. The theoretical relationship between position, speed and acceleration conforms to the classic square root formula. According to this formula, the positioning speed is derived Calculated as follows:

In the formula: V is the positioning speed; A _setp is the positioning acceleration; ΔS is the position deviation.

The positioning setting speed curve can be obtained as shown in the left picture of Figure 6 below. When the position deviation is large, the speed curve calculated by this formula is relatively smooth and can fully meet the control requirements. However, when the position deviation is small, the speed curve calculated by this formula is very steep, and the speed change is too drastic and cannot be directly applied.

When the position deviation is less than ΔS', the square root formula is no longer used for calculation, but the following linearization formula is used for calculation.

In the formula: V is the positioning speed; a is the slope of the linearized straight line; ΔS is the position deviation and ≤ ΔS'; A _setp is the positioning acceleration; ΔS' is the position deviation switching point of the two calculation formulas.

The linearized formula is obtained:

In the formula: V is the positioning speed; T _p is the acceleration rounding time; A _setp is the positioning acceleration; ΔS is the position deviation.

Move the curve on the left side of Figure 6 to the right by ΔS' to get the speed curve starting from zero, as shown on the right side of Figure 6 below, which is the optimized square root speed curve. Taking into account the influence of the acceleration fillet curve of each segment, the calculation formula is:

In the formula: V is the positioning speed; '+' is the entrance looper/'-' is the outlet looper; SIGN is the position difference ΔS sign, 1=positive, -1=negative; T _p is the acceleration rounding time; A _setp is the positioning acceleration; ΔS is the position deviation; S _r =A _setp ×T _p ² /6, is the acceleration smoothing distance.

For the entrance looper, the total positioning setting speed of the entrance section is V _IN =V _OUT +V. As can be seen from the right picture of Figure 6 below, when the position difference ΔS is larger, the calculated positioning speed V is larger.

When the position difference ΔS is greater than a certain value, the calculated total positioning set speed will exceed the upper limit of the entrance section speed. Then, when the position difference ΔS is greater than this value, the positioning control still calculates the positioning speed V in real time, and takes the smaller value of the maximum speed V _INmax of the entrance section and the total positioning set speed V _OUT +V as the speed setting of the entrance section, As shown in area ① in Figure 7 below. Export loopers are similar.

2. Looper positioning control based on PI regulator

The first part of the looper positioning is completed by the square root curve, and linearization is used when the looper deviation is small. When the looper deviation is extremely small, in order to obtain better control effects, a PI controller is used for position control. The calculation formula is as follows:

In the formula: '+' is the entrance looper/'-' is the outlet looper; V is the positioning speed; K _P is the proportional coefficient; ΔS _n is the position deviation of this period (S _r <|ΔS|); T is the sampling period ;T _i is the integration time.

The positioning process of the strip in the looper is divided into four parts for control, which improves the positioning control accuracy of the looper. The calculated positioning speed is used as the speed limiter value of the inlet and outlet section, thus realizing the inlet and outlet speed to automatically follow the speed of the process section. Automatic speed control function; through conversion, the positioning of the looper car is converted into the positioning of the strip within the looper. For the control object - the speed of the inlet and outlet strip, the control method after conversion is more intuitive and is more conducive to process optimization in the production process and Equipment maintenance; pre-calculate the compensation value of the actual strip position at the moment when the looper positioning is started. As the pre-control value for the looper positioning control, it greatly reduces the positioning overshoot that occurs during the looper positioning process and improves the positioning control accuracy. At the same time, the adjustment range of the inlet and outlet speeds caused by positioning overshoot is reduced, and the stability of the speed control is improved; before the looper positioning is started, only the position of the looper is monitored in real time, and the speed of the inlet and outlet is not interfered. The operator can adjust the speed according to the unit The speed can be adjusted freely according to the situation, which improves the freedom and convenience of this function; after positioning is started, deceleration positioning is performed based on the process acceleration of the inlet and outlet, which not only meets the positioning requirements but also meets the requirements of process control, and at the same time reduces the positioning deceleration distance to Minimum, ensuring the stability of the unit and improving production efficiency; according to the position deviation range, the positioning process is divided into three stages of control, which improves the position control accuracy and ensures the smooth entry and exit positioning speed.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims

A control method for automatic adjustment of the entrance and exit speed of a cold rolling production line, which is characterized by: realizing it through looper positioning. The first step is to calculate the position deviation compensation of the looper: first, convert the positioning of the looper car into the strip inside the looper through conversion. positioning, and then use the acceleration and acceleration rounding time values of the inlet and outlet sections to pre-calculate the acceleration rounding time compensation value and acceleration direction change compensation value of the actual strip position at the moment when the inlet and outlet looper positioning is started, as the looper positioning control Pre-control value; the second step is to calculate the positioning speed setting value of the looper: take the inlet and outlet speed difference of the looper as the positioning speed, optimize the square root curve of the positioning speed, and obtain the linearization segment and the square root curve segment. The position deviation is in turn In the process of decreasing, when the positioning speed is greater than the maximum allowable speed, only the positioning start point is monitored. When the positioning deviation is within the square root curve segment, the positioning set speed is calculated using the square root formula using the positioning deviation and positioning acceleration. When the positioning deviation is online When the positioning deviation is within the range of the linearization section, the positioning set speed is calculated using the linearization formula. When the positioning deviation is within the acceleration rounded smoothing distance range, the positioning speed is controlled through the PI regulator.
The control method for automatic adjustment of the entrance and exit speed of a cold rolling production line as claimed in claim 1, characterized in that: when converting the positioning of the looper car into the positioning of the strip within the looper, the method is: the entrance and exit speeds V IN and V of the looper OUT is the strip speed, and the looper's sleeve amount reflects the position of the looper car between the empty sleeve position and the full sleeve position. First, the sleeve amount is uniformly converted into the strip length value, and the sleeve amount control is converted into a live loop. The calculation formula for the positioning control of the strip within the loop is S = C × L , and then convert the set amount deviation value between the set amount of the looper and the actual set amount of the looper into the position deviation ΔS of the strip. The calculation formula is ΔS=C setp ×L×NC act ×L×N, where, C setp is the set amount of the looper %, and C act is the actual amount of the looper %.
The control method for automatic adjustment of the entrance and exit speed of a cold rolling production line as claimed in claim 1, characterized in that: when calculating the acceleration fillet time compensation value of the actual strip position, the method is: in order to obtain a smooth speed curve, the cold rolling production line The acceleration is applied to each section of the production line through a rounded smooth curve. T p is the acceleration rounding time. Due to the existence of the acceleration rounding time T p , the actual distance traveled by the entrance and exit sections of the production line during constant speed startup for looper positioning is compared. The assumption should be large and should be taken into account in advance when calculating the actual positioning distance. The calculation formula is:

Among them, S c1 is the acceleration fillet time compensation value of the actual positioning distance; V IN is the looper inlet speed; V OUT is the looper exit speed; A setp is the positioning acceleration, which is the normal operating acceleration of the entrance section or exit section.
The control method for automatic adjustment of the entrance and exit speed of a cold rolling production line as claimed in claim 1, characterized in that: when calculating the acceleration direction change compensation value of the actual strip position, the method is: in order to obtain a smooth speed curve, the cold rolling production line Acceleration is applied to each section of the production line through a rounded smooth curve. T p is the acceleration rounding time. If the entrance and exit sections are accelerating and decelerating before positioning is started, and positioning control will cause the acceleration direction to change, then its acceleration will be inevitable after positioning is started. First go through the fillet curve to 0, and then perform acceleration and deceleration during the positioning process. When calculating the actual positioning distance, you must take it into consideration in advance. The calculation formula is:

Among them, S c2 is the acceleration direction change compensation value of the actual positioning distance; V IN is the looper inlet speed; V OUT is the looper exit speed; A is the actual acceleration of the entrance section or exit section at the moment of positioning start; A setp is the positioning acceleration , which is the normal operating acceleration of the entrance section or exit section; T'=A×T p /A setp , which is the time required for the acceleration to reach zero through the fillet curve.
The control method for automatic adjustment of the inlet and outlet speed of a cold rolling production line as claimed in claim 1, characterized in that: taking the inlet and outlet speed difference of the looper as the positioning speed, and optimizing the square root curve of the positioning speed, the method is: the looper positioning device The position deviation between the fixed value and the actual value and the positioning acceleration are the basis for calculating the positioning speed of the looper. The theoretical relationship between position, speed and acceleration conforms to the classic square root formula. According to the square root formula, the positioning speed calculation formula is derived:

Among them, V is the positioning speed; A setp is the positioning acceleration; ΔS is the position deviation;

When the position deviation is large, the speed curve calculated by the previous formula is relatively smooth and can meet the control requirements. However, when the position deviation is small, the speed curve calculated by the previous formula is very steep and the speed change is too drastic and cannot be directly applied;

When the position deviation is less than ΔS', the previous formula is no longer used for calculation, and the linearized formula is used instead.

Among them, a is the slope of the linearized straight line; ΔS ≤ ΔS'; ΔS' is the position deviation switching point of the two calculation formulas;

According to the characteristics of the square root curve, select the optimal switching point
The linearization formula is obtained as

Among them, T p is the acceleration rounding time;

Shift the curve to the right by ΔS' to get the speed curve starting from zero, which is the square root curve of the optimized positioning speed. Taking into account the influence of the acceleration fillet curve of each section, the calculation formula is:

Among them, '+' is the entrance looper/'-' is the outlet looper; SIGN is the position deviation ΔS sign, 1=positive, -1=negative; S r =A setp ×T p 2 /6, which is the acceleration smoothing distance .
The control method for automatic adjustment of the entrance and exit speed of a cold rolling production line as claimed in claim 1, characterized in that: only monitoring the positioning start point is performed when the positioning speed is greater than the maximum allowable speed. The specific method is: when the position deviation ΔS is greater than a certain value , the calculated total positioning set speed will exceed the speed upper limit of the entrance section or exit section, then when the position deviation ΔS is greater than the speed upper limit, the positioning control still calculates the positioning speed V in real time. For the entrance looper, the maximum speed V of the entrance section is taken The smaller value of INmax and the total positioning set speed V OUT +V is used as the speed setting of the entrance section. For the outlet looper, the smaller value of the maximum speed V OUTmax of the outlet section and the total positioning set speed V IN +V is taken. The value is used as the speed setting for the exit section.
The control method for automatic adjustment of the entrance and exit speed of a cold rolling production line as claimed in claim 1, characterized in that: when the positioning deviation is within the acceleration rounded smoothing distance range, the positioning speed is controlled through the PI regulator. The specific method is: when the positioning deviation is within the acceleration rounded smoothing distance range, the specific method is: When the set deviation is extremely small, in order to obtain better control effects, a PI controller is used for position control. The calculation formula is:

Among them, '+' is the entrance looper/'-' is the outlet looper; V is the positioning speed; K P is the proportional coefficient; ΔS n is the position deviation of this cycle; T is the sampling period; T i is the integration time.