CN114749491A - Control method for automatically adjusting inlet and outlet speeds of cold rolling production line - Google Patents

Control method for automatically adjusting inlet and outlet speeds of cold rolling production line Download PDF

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CN114749491A
CN114749491A CN202210270398.5A CN202210270398A CN114749491A CN 114749491 A CN114749491 A CN 114749491A CN 202210270398 A CN202210270398 A CN 202210270398A CN 114749491 A CN114749491 A CN 114749491A
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positioning
loop
speed
acceleration
inlet
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CN114749491B (en
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宋军
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Wisdri Engineering and Research Incorporation Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/48—Tension control; Compression control
    • B21B37/50—Tension control; Compression control by looper control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2273/00—Path parameters
    • B21B2273/24—Web positioning
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
    • Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

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  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
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Abstract

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

Description

Control method for automatically adjusting inlet and outlet speeds of cold rolling production line
Technical Field
The invention relates to electrical control of a cold rolling production line, in particular to a control method for automatically adjusting the inlet and outlet speeds of the cold rolling production line.
Background
As shown in fig. 1 below, the unit arrangement of the cold rolling production line generally comprises an inlet section, an inlet loop, a process section, an outlet loop and an outlet section according to the requirements of the process production; in the inlet section, the raw material roll is unfolded, cut and welded; in the process section, the continuous strip steel is subjected to scale breaking, straightening, cleaning, degreasing, annealing, flattening, rolling, coating and other process treatments; and finishing the cutting of the continuous strip steel after the process treatment and the coiling of the finished product coil at the outlet section. In order to ensure the process treatment quality of the strip steel, improve the unit yield and reduce the energy consumption, the running speed of the strip steel in a process section in the production process is generally required to be kept stable. When the strip steel at the inlet section is decelerated even stops for a short time due to drifting, threading, shearing, welding and the like, the strip steel stored in the inlet loop (5) maintains the stability of the running speed of the strip steel at the process section in the time. Similarly, when the strip steel at the outlet section is decelerated or even stopped in the quality inspection, tail flicking, shearing and threading processes of the outlet section, the speed of the process section is maintained to be stable by filling the outlet loop (8).
The vertical loop structure and loop tension/position control are shown in fig. 2, and the horizontal loop is similar to the vertical loop structure: a loop motor (15) drags a loop vehicle (22) to reciprocate up and down through a loop winch (13) and a loop steel rope (21) to complete the loop charging and discharging actions, the lowest position of the loop vehicle (22) is an empty loop position, the loop amount is 0%, the highest position of the loop vehicle (22) is a full loop position, the loop amount is 100%, the effective stroke of the loop vehicle (22) is arranged between the empty loop position and the full loop position, and the length is L.
In order to guarantee the stability of the speed of the process section to the maximum extent, the inlet loop (5) is required to keep the high loop quantity as much as possible, and the outlet loop (8) is required to keep the low loop quantity as much as possible in the production process: when the inlet or outlet section returns to normal operation from a decelerated or stopped condition, it will typically rapidly accelerate to a speed above that of the process section, charging the inlet loop (5) or discharging the outlet loop (8). When the inlet loop (5) reaches a set high loop quantity or the outlet loop (8) reaches a set low loop quantity, the inlet section or the outlet section is decelerated to be at the same speed as the process section so as to maintain the loop quantities of the inlet loop (5) and the outlet loop (8) to be kept near a set value; the general method of the control process is to directly adopt a PI regulator and realize the automatic regulation of the speed of the inlet and outlet sections by controlling the sleeve amount of the loops (5 and 8).
However, the acceleration and deceleration rate of the normal production of the unit is preset according to the process requirements and cannot be changed at will, and an operator may not accelerate according to the output curve of the regulator in the process of accelerating the inlet and outlet, so that the PI regulator is saturated, and the PI parameters may not adapt to the conditions that all the sets of quantity difference ranges oscillate in the process of regulating the inlet and outlet at the same speed as the process section, and the like, so that the requirement of control cannot be well met by using the PI regulation alone, which is a dilemma encountered by the automatic regulation of the inlet and outlet speeds of the cold rolling production line at present.
Disclosure of Invention
The invention aims to provide a control method for automatically adjusting the inlet and outlet speeds of a cold rolling production line, which divides the positioning process into a plurality of sections according to the position deviation range, improves the position control precision, ensures the smoothness of the inlet and outlet positioning speeds, is more beneficial to process optimization and equipment maintenance in the production process, improves the stability of speed control, improves the degree of freedom and convenience, ensures the stability of a unit and improves the production efficiency.
The technical scheme adopted by the invention is as follows:
a control method for automatically adjusting the speed of an inlet and an outlet of a cold rolling production line is realized by loop positioning, wherein the first step is calculating the position deviation compensation of a loop: firstly, converting the loop positioning into the loop inner strip steel positioning through conversion, and then pre-calculating an acceleration fillet time compensation value and an acceleration direction change compensation value of the actual strip steel position at the inlet and outlet loop positioning starting moment by using the acceleration and the acceleration fillet time value of the inlet and outlet sections as a pre-control value of loop positioning control; the second step is to calculate the set value of the positioning speed of the loop: the method comprises the steps of optimizing a square root curve of a positioning speed by taking a speed difference between an inlet and an outlet of a loop as the positioning speed to obtain a linearized section and a square root curve section, monitoring a positioning starting point only when the positioning speed is higher than a maximum allowable speed in the process of sequentially reducing the position deviation, calculating a positioning set speed by using a positioning deviation and a positioning acceleration through a square root formula when the positioning deviation is within the range of the square root curve section, calculating the positioning set speed by using the positioning deviation through the linearized formula when the positioning deviation is within the range of the linearized section, and controlling the positioning speed through a PI regulator when the positioning deviation is within the range of an acceleration fillet smooth distance.
Further, when the loop car positioning is converted into the loop inner strip steel positioning, the method comprises the following steps: of a loopInlet and outlet velocity VINAnd VOUTThe method is characterized in that the speed of strip steel and the loop quantity of a loop reflect the position of a loop vehicle between an empty loop position and a full loop position, the loop quantity is uniformly converted into a length value of the strip steel, the loop quantity control is converted into the positioning control of the strip steel in the loop, the calculation formula is S ═ CxLxN, wherein S is the position of the strip steel, C is the loop quantity, L is the physical length of the loop, and N is the number of layers of the strip steel in the loop, then the loop quantity deviation value between the loop quantity setting value and the actual loop quantity of the loop is converted into the position deviation Delta S of the strip steel, and the calculation formula is that Delta S ═ Csetp×L×N-CactX L X N, wherein CsetpSetting the loop amount% for loop CactIs the actual loop quantity of the loop.
Further, when calculating the acceleration fillet time compensation value of the actual strip steel position, the method comprises the following steps: in order to obtain a smooth speed profile, the acceleration of the cold rolling line is applied to the line sections by means of a fillet smoothing curve, TpAcceleration fillet time, due to acceleration fillet time TpThe actual distance of the inlet and outlet sections of the production line in the process of positioning the loop by starting at a constant speed is larger than the assumed actual distance, the actual positioning distance is calculated by taking the actual distance into account in advance, and the calculation formula is
Figure BDA0003553053820000031
Wherein S isc1An acceleration fillet time compensation value for the actual positioning distance; vINIs the loop entry velocity; vOUTIs the speed of the loop outlet; a. thesetpThe positioning acceleration is the normal running acceleration of the inlet section or the outlet section.
Further, when the acceleration direction change compensation value of the actual strip steel position is calculated, the method comprises the following steps: in order to obtain a smooth speed profile, the acceleration of the cold rolling line is applied to the line sections by means of a fillet smoothing curve, TpFor acceleration fillet time, if the inlet and outlet sections are accelerating or decelerating before positioning start and positioning control will cause the acceleration direction to change, then at positioning startThe acceleration of the movable positioning device is inevitably 0 through a fillet curve after the movement, then the acceleration and the deceleration of the positioning process are carried out, the actual positioning distance is calculated by taking the actual positioning distance into consideration in advance, and the calculation formula is
Figure BDA0003553053820000032
Wherein S isc2An acceleration direction change compensation value for the actual positioning distance; vINIs the loop inlet speed; vOUTThe speed of the loop outlet is; a is the actual acceleration of the inlet section or the outlet section at the moment of positioning and starting; a. thesetpThe positioning acceleration is the normal running acceleration of the inlet section or the outlet section; t ═ A × Tp/AsetpThe time required for the acceleration to go through the fillet curve to zero.
Further, the speed difference of the inlet and the outlet of the loop is taken as the positioning speed, and when the square root curve of the positioning speed is optimized, the method comprises the following steps: the position deviation and the positioning acceleration between the set value and the actual value of the loop positioning are the basis for calculating the loop positioning speed, the theoretical relationship among the position, the speed and the acceleration accords with a classical square root formula, and the calculation formula for obtaining the positioning speed by derivation according to the square root formula is
Figure BDA0003553053820000033
Wherein V is the positioning speed; a. thesetpTo position the acceleration; Δ S is a position deviation;
when the position deviation is large, the speed curve calculated by the previous formula is smooth and can meet the control requirement, but when the position deviation is small, the speed curve calculated by the previous formula is steep, the speed change is too violent, and the speed curve cannot be directly applied;
when the position deviation is less than delta S', the calculation is not carried out by adopting the previous formula, but is carried out by adopting a linear formula
Figure BDA0003553053820000041
Wherein a is the slope of the linearization line; delta S is less than or equal to Delta S'; Δ S' is the two calculation formula position deviation switching points;
selecting an optimal switching point according to the characteristics of a square root curve
Figure BDA0003553053820000042
The resulting linearized equation is:
Figure BDA0003553053820000043
wherein, TpAcceleration fillet time;
the curve is shifted to the right by delta S' to obtain a speed curve from zero, namely a square root curve of the optimized positioning speed, the influence of acceleration fillet curves of all sections is considered, and the calculation formula is
Figure BDA0003553053820000044
Wherein '+' is an inlet loop/'-' is an outlet loop; SIGN is the SIGN of the position deviation Δ S, 1 is positive, -1 is negative; s. ther＝Asetp×Tp 2And/6, acceleration smoothing distance.
Further, when the positioning speed is greater than the maximum allowable speed, only monitoring the positioning starting point is carried out, and the specific method comprises the following steps: when the position deviation delta S is larger than a certain value, the calculated total positioning set speed exceeds the upper speed limit of the inlet section or the outlet section, when the position deviation delta S is larger than the upper speed limit, the positioning control still calculates the positioning speed V in real time, and for the inlet loop, the maximum speed V of the inlet section is takenINmaxAnd a total positioning set speed VOUTThe lower value of + V is set as the speed of the inlet section, and for the outlet loop, the maximum speed V of the outlet section is taken outOUTmaxAnd a total positioning set speed VINThe smaller value of + V is set as the speed of the outlet section.
Further, when the positioning deviation is within the range of the smooth distance of the acceleration fillet, the positioning speed is controlled through a PI regulator, and the specific method comprises the following steps: when the deviation of the loop is extremely small, in order to obtain better control effect, the position control is carried out by adopting a PI controller, and the calculation formula is
Figure BDA0003553053820000045
Wherein '+' is an inlet loop/'-' is an outlet loop; v is the positioning speed; k PIs a proportionality coefficient; delta SnThe position deviation of the period; t is a sampling period; t isiIs the integration time.
The invention has the beneficial effects that:
the positioning process of the strip steel in the loop is divided into four parts for control, the positioning control precision of the loop is improved, and the calculated positioning speed is used as the speed limiting value of the inlet and outlet section, so that the automatic speed control function that the inlet and outlet speed automatically follows the speed of the process section is realized;
the loop car positioning is converted into the loop inner strip steel positioning through conversion, and for the speed of the control object, namely the strip steel entering and exiting, the control mode after conversion is more intuitive, and the process optimization and equipment maintenance in the production process are more facilitated;
the compensation value of the actual strip steel position is pre-calculated at the moment of loop positioning starting and is used as a pre-control value for loop positioning control, so that positioning overshoot in the loop positioning process is greatly reduced, the positioning control precision is improved, the inlet and outlet speed adjusting range caused by the positioning overshoot is reduced, and the stability of speed control is improved;
before the loop is positioned and started, only the position of the loop is monitored in real time, the speed of the loop entering and exiting is not interfered, an operator can freely adjust the speed according to the condition of a unit, and the degree of freedom and convenience of the function are improved;
After the positioning is started, the speed is reduced and positioned by the process acceleration of the inlet and the outlet, the positioning requirement is met, the requirement of process control is met, the positioning speed reduction distance is reduced to the minimum, the stability of the unit is ensured, and the production efficiency is improved;
according to the position deviation range, the positioning process is divided into three sections for control, so that the position control precision is improved, and the smoothness of the inlet and outlet positioning speed is ensured.
Drawings
FIG. 1 is a schematic diagram of a typical block layout of a cold rolling continuous line.
Fig. 2 is a schematic view of an inlet vertical loop configuration and loop tension/position control.
FIG. 3 is a schematic view of an acceleration fillet curve of each section of a cold rolling production line.
FIG. 4 is a schematic diagram of the calculation of the acceleration fillet time compensation value in the actual calculation of the position of the strip steel for loop positioning.
FIG. 5 is a schematic diagram of the calculation of the acceleration direction change compensation value in the actual calculation of the position of the strip steel for loop positioning.
FIG. 6 is a schematic diagram of the calculation of the square root curve optimization before and after loop positioning speed set point.
FIG. 7 is a schematic view of a complete loop positioning speed setting curve, using an inlet loop as an example; the area I is a loop positioning monitoring area, the area II is a loop positioning square root curve area, the area III is a loop positioning linearization area, and the area IV is a loop positioning PI control area.
In the figure: 1-uncoiling machine; 2-inlet shearing; 3-welding machine; 4-inlet loop inlet tension roller; 5-inlet loop; 6-inlet loop outlet tension roller; 7-outlet loop inlet tension roller; 8-outlet loop; 9-outlet loop outlet tension roller; 10-export scissors; 11-a coiler; 12-a looper absolute value encoder; 13-looping winding engine; 14-a looper gearbox; 15-a looping motor; 16-a looper incremental encoder; 17-inlet tension roller incremental encoder; 18-inlet tension roller motor; 19-inlet tension roller gearbox; 20-looping bottom rollers; 21-looping steel ropes; 22-looping car; 23-looping tower base; 24-looping tensiometer roller.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the drawings.
A control method for automatically adjusting the speed of an inlet and an outlet of a cold rolling production line is realized by positioning a loop, and the first step is to calculate the position deviation compensation of the loop: firstly, converting the loop positioning into the loop inner strip steel positioning through conversion, and then pre-calculating an acceleration fillet time compensation value and an acceleration direction change compensation value of the actual strip steel position at the inlet and outlet loop positioning starting moment by using the acceleration and the acceleration fillet time value of the inlet and outlet sections as a pre-control value of loop positioning control; the second step is to calculate the set value of the positioning speed of the loop: the method comprises the steps of optimizing a square root curve of a positioning speed by taking a speed difference between an inlet and an outlet of a loop as the positioning speed to obtain a linearized section and a square root curve section, monitoring a positioning starting point only when the positioning speed is higher than a maximum allowable speed in the process of sequentially reducing the position deviation, calculating a positioning set speed by using a positioning deviation and a positioning acceleration through a square root formula when the positioning deviation is within the range of the square root curve section, calculating the positioning set speed by using the positioning deviation through the linearized formula when the positioning deviation is within the range of the linearized section, and controlling the positioning speed through a PI regulator when the positioning deviation is within the range of an acceleration fillet smooth distance. The specific process is as follows:
Position deviation compensation
As shown in FIG. 2 (FIG. 2 is a schematic view of an inlet loop, and an outlet loop is similar), the inlet and outlet velocities V of the loopINAnd VOUTThe speed of the strip steel is adopted, and the loop quantity of the loop reflects the position of the loop vehicle between an empty loop position and a full loop position. For the convenience of analysis, the sleeve quantity is uniformly converted into a length value of the strip steel, the sleeve quantity control is converted into positioning control of the strip steel in the live sleeve, and a calculation formula is as follows:
S＝C×L×N
in the formula: s is the position of the strip steel; c is the loop amount; l is the physical length of the loop; n is the number of layers of the strip steel in the live sleeve.
The set value deviation (%) between the set loop amount (%) and the actual loop amount (%, calculated by an absolute value encoder) of the loop is converted into the position deviation Δ S of the strip steel by the above formula. The calculation formula is as follows:
ΔS＝Csetp×L×N-Cact×L×N
in the formula: Δ S is a position deviation; csetpSetting the loop quantity for the loop; cactIs the actual loop amount of the loop; l is the physical length of the loop; n is the number of layers of the strip steel in the live sleeve.
The loop positioning control is necessarily accompanied by a speed change of the inlet and outlet sections. In order to obtain a smooth speed profile, the acceleration of the cold rolling line is applied to the line sections by means of a fillet smoothing curve, as in fig. 3, a without a smooth speed profile, b with a smooth speed profile, T pAcceleration rounding time.
1. Acceleration fillet time compensation
Due to the existence of the acceleration fillet time, the actual distance traveled by the inlet and outlet sections of the production line during the process of positioning the loop at the constant speed start is larger than the assumed distance, as shown in the following shaded area c in fig. 4 as the assumed positioning distance, and the shaded area d as the actual excessive positioning distance traveled according to the acceleration during the operation under the condition of the fillet time, the actual positioning distance is considered in advance when the actual positioning distance is calculated. The calculation formula of the partial area is as follows:
Figure BDA0003553053820000071
in the formula: s. thec1An acceleration fillet time compensation value for the actual positioning distance; vINIs the loop entry velocity; voUTThe speed of the loop outlet is; t ispAcceleration fillet time for an inlet section (positioned corresponding to an inlet loop) or an outlet section (positioned corresponding to an outlet loop); a. thesetpIs the positioning acceleration, i.e. the normal operating acceleration of the inlet section (positioned corresponding to the inlet loop) or the outlet section (positioned corresponding to the outlet loop).
2. Acceleration direction change compensation
If the inlet and outlet sections are accelerating and decelerating before positioning and starting, and the acceleration direction is changed due to positioning control, the acceleration of the positioning and starting section inevitably passes through the fillet curve to 0 firstly, then the acceleration and the deceleration in the positioning process are carried out, as shown in the following figure 5, the shadow area e in the figure is the positioning distance of the running of the strip steel in the process that the acceleration passes through the fillet curve to 0 under the condition, and the actual positioning distance needs to be considered in advance when the actual positioning distance is calculated. The formula for calculating the partial area is as follows:
Figure BDA0003553053820000072
In the formula: sc2An acceleration direction change compensation value for the actual positioning distance; vINIs the loop inlet speed; vOUTThe speed of the loop outlet is; a is the actual acceleration of the inlet section (corresponding to inlet loop positioning) or the outlet section (corresponding to outlet loop positioning) at the moment of positioning and starting; t ispAcceleration fillet time for an inlet section (positioned corresponding to an inlet loop) or an outlet section (positioned corresponding to an outlet loop); a. thesetpThe normal running acceleration of the inlet section (corresponding to the inlet loop positioning) or the outlet section (corresponding to the outlet loop positioning) is the positioning acceleration; t ═ A × Tp/AsetpThe time required for the acceleration to go through the fillet curve to zero.
Second, calculating the set value of the positioning speed of the loop
For the inlet loop, when the process section velocity (i.e., the outlet velocity V of the inlet loop)OUT) The speed of the inlet section (i.e. the inlet speed V of the inlet loop) while remaining stableIN) Higher than VOUTWhen the bag is filled, below VOUTThe speed difference of the inlet and the outlet of the loop determines the action of the charging and discharging sleeve and the speed of the charging and discharging sleeve. Inlet speed V of inlet loopINSplitting into VOUT+ V is the speed difference between inlet and outlet of inlet loop, then, the inlet speed V is regulatedINThe realization of the positioning control of the inlet loop can be converted into the realization of the adjustment of the speed difference V between the inlet and the outlet of the inlet loop.
Likewise, for the outlet looper, the inlet velocity VINIs the process section velocity, the exit velocity VOUT(＝VIN+ V) is the velocity of the outlet section by adjusting the velocity V of the outlet sectionOUTThe realization of the positioning control of the outlet loop can be converted into the adjustment of the outlet loopIs realized by the inlet and outlet speed difference V.
1. Loop positioning control based on square root curve
The position deviation and the positioning acceleration between the set value and the actual value of the loop positioning are the basis for calculating the loop positioning speed, the theoretical relationship among the position, the speed and the acceleration accords with a classical square root formula, and the calculation formula of the positioning speed is obtained by deduction according to the formula as follows:
Figure BDA0003553053820000081
in the formula: v is the positioning speed; a. thesetpPositioning acceleration is adopted; Δ S is a positional deviation.
The positioning set speed curve can be obtained as shown in the left graph of fig. 6, and when the position deviation is large, the speed curve calculated by the formula is smooth and can completely meet the control requirement. However, when the position deviation is small, the velocity curve calculated by the formula is steep, and the velocity change is too violent to be directly applied.
When the position deviation is smaller than Δ S', the square root formula is not used, and the following linearization formula is used instead.
Figure BDA0003553053820000082
In the formula: v is the positioning speed; a is the slope of the linearization line; delta S is a position deviation and is less than or equal to Delta S'; a. the setpTo position the acceleration; Δ S' is the two calculation formula position deviation switching points.
Selecting an optimal switching point according to the characteristics of a square root curve
Figure BDA0003553053820000083
The resulting linearized equation is:
Figure BDA0003553053820000084
in the formula: v is the positioning speed; t ispAcceleration fillet time; a. thes2tpPositioning acceleration is adopted; Δ S is a positional deviation.
Shifting the curve of the left plot of figure 6 below to the right by Δ S' results in a velocity curve starting from zero, as shown in the right plot of figure 6 below, i.e., the optimized square root velocity curve. Considering the influence of each acceleration fillet curve, the calculation formula is as follows:
Figure BDA0003553053820000091
in the formula: v is the positioning speed; '+' is an inlet loop/'-' is an outlet loop; SIGN is the SIGN of position difference Δ S, 1 is positive, and-1 is negative; t ispAcceleration fillet time; a. thesetpPositioning acceleration is adopted; Δ S is a position deviation; sr＝Asetp×Tp 2And 6, the acceleration smooth distance.
For the inlet loop, the inlet section is always positioned at a set speed VIN＝VOUT+ V. As can be seen from the right diagram of fig. 6 below, the calculated positioning velocity V is larger as the position difference Δ S is larger.
When the position difference Δ S is greater than a certain value, the calculated total positioning set speed exceeds the upper limit of the inlet stage speed. Then, when the position difference Δ S is larger than the value, the positioning control still calculates the positioning speed V in real time, and the maximum speed V of the inlet section is taken INmaxAnd a total positioning set speed VOUTThe smaller value of + V is set as the speed of the inlet section, as shown by the region (r) in fig. 7 below. The outlet loop is similar.
2. Loop positioning control based on PI regulator
The first part of loop positioning is completed by a square root curve, and a linearization mode is adopted when the loop deviation is small. When the deviation of the loop is extremely small, in order to obtain better control effect, a PI controller is adopted to carry out position control. The calculation formula is as follows:
Figure BDA0003553053820000092
in the formula: '+' is an inlet loop/'-' is an outlet loop; v is the positioning speed; kPIs a proportionality coefficient; delta SnIs the local period position deviation (S)r<| Δ S |); t is a sampling period; t isiIs the integration time.
The positioning process of the strip steel in the loop is divided into four parts for control, the positioning control precision of the loop is improved, and the calculated positioning speed is used as the speed limiting value of the inlet and outlet section, so that the automatic speed control function that the inlet and outlet speed automatically follows the speed of the process section is realized; the loop car positioning is converted into the loop inner strip steel positioning through conversion, and for the speed of the control object, namely the strip steel entering and exiting, the control mode after conversion is more intuitive, and the process optimization and equipment maintenance in the production process are more facilitated; the compensation value of the actual strip steel position is pre-calculated at the moment of loop positioning starting and is used as a pre-control value for loop positioning control, so that positioning overshoot in the loop positioning process is greatly reduced, the positioning control precision is improved, the inlet and outlet speed adjusting range caused by the positioning overshoot is reduced, and the stability of speed control is improved; before the loop is positioned and started, only the position of the loop is monitored in real time, and the speed of the loop entering the outlet is not interfered, so that an operator can freely adjust the speed according to the condition of the unit, and the degree of freedom and convenience of the function are improved; after the positioning is started, the speed is reduced and positioned by the process acceleration of the inlet and the outlet, the positioning requirement is met, the requirement of process control is met, the positioning speed reduction distance is reduced to the minimum, the stability of the unit is ensured, and the production efficiency is improved; according to the position deviation range, the positioning process is divided into three sections for control, so that the position control precision is improved, and the smoothness of the inlet and outlet positioning speed is ensured.
It will be appreciated that modifications and variations are possible to those skilled in the art in light of the above teachings, and it is intended to cover all such modifications and variations as fall within the scope of the appended claims.

Claims (7)

1. A control method for automatically adjusting the inlet and outlet speeds of a cold rolling production line is characterized by comprising the following steps: the method is realized by loop positioning, and the first step is to calculate the position deviation compensation of a loop: firstly, converting the loop positioning into the loop inner strip steel positioning through conversion, and then pre-calculating an acceleration fillet time compensation value and an acceleration direction change compensation value of the actual strip steel position at the inlet and outlet loop positioning starting moment by using the acceleration and the acceleration fillet time value of the inlet and outlet sections as a pre-control value of loop positioning control; the second step is to calculate the set value of the positioning speed of the loop: the method comprises the steps of optimizing a square root curve of a positioning speed by taking a speed difference between an inlet and an outlet of a loop as the positioning speed to obtain a linearized section and a square root curve section, monitoring a positioning starting point only when the positioning speed is higher than a maximum allowable speed in the process of sequentially reducing the position deviation, calculating a positioning set speed by using a positioning deviation and a positioning acceleration through a square root formula when the positioning deviation is within the range of the square root curve section, calculating the positioning set speed by using the positioning deviation through the linearized formula when the positioning deviation is within the range of the linearized section, and controlling the positioning speed through a PI regulator when the positioning deviation is within the range of an acceleration fillet smooth distance.
2. The control method for automatically adjusting the inlet and outlet speed of a cold rolling line according to claim 1, wherein: when the loop vehicle positioning is converted into the loop inner strip steel positioning, the method comprises the following steps: speed V of inlet and outlet of loopINAnd VOUTThe method is characterized in that the speed of strip steel and the loop quantity of a loop reflect the position of a loop vehicle between an empty loop position and a full loop position, the loop quantity is uniformly converted into a length value of the strip steel, the loop quantity control is converted into the positioning control of the strip steel in the loop, the calculation formula is S ═ CxLxN, wherein S is the position of the strip steel, C is the loop quantity, L is the physical length of the loop, and N is the number of layers of the strip steel in the loop, then the loop quantity deviation value between the loop quantity setting value and the actual loop quantity of the loop is converted into the position deviation Delta S of the strip steel, and the calculation formula is that Delta S ═ Csetp×L×N-CactX L X N, wherein CsetpSetting the loop amount% for loop CactIs the actual loop quantity of the loop.
3. The control method for automatically adjusting the inlet and outlet speed of a cold rolling line according to claim 1, wherein: when the acceleration fillet time compensation value of the actual strip steel position is calculated, the method comprises the following steps: in order to obtain a smooth speed profile, the acceleration of the cold rolling line is applied to the line sections by means of a fillet smoothing curve, T pAcceleration fillet time, due to acceleration fillet time TpThe actual distance of the inlet and outlet sections of the production line in the process of positioning the loop by starting at a constant speed is larger than the assumed actual distance, the actual positioning distance is calculated by taking the actual distance into account in advance, and the calculation formula is
Figure FDA0003553053810000011
Wherein S isc1An acceleration fillet time compensation value for the actual positioning distance; vINIs the loop inlet speed; vOUTThe speed of the loop outlet is; a. thesetpThe positioning acceleration is the normal running acceleration of the inlet section or the outlet section.
4. The control method for automatically adjusting the inlet and outlet speed of a cold rolling line according to claim 1, wherein: when the acceleration direction change compensation value of the actual strip steel position is calculated, the method comprises the following steps: in order to obtain a smooth speed profile, the acceleration of the cold rolling line is applied to the line sections by means of a fillet smoothing curve, TpFor acceleration fillet time, if the inlet and outlet sections are accelerating and decelerating before positioning start, and the direction of acceleration is changed due to positioning control, the acceleration of the positioning start is inevitably 0 through a fillet curve, then the acceleration and the deceleration in the positioning process are carried out, the actual positioning distance is calculated by taking the acceleration into account in advance, and the calculation formula is that
Figure FDA0003553053810000021
Wherein S isc2Compensating values for acceleration direction changes of the actual positioning distance; vINIs the loop entry velocity; vOUTThe speed of the loop outlet is; a is the actual acceleration of the inlet section or the outlet section at the moment of positioning and starting; a. thesetpThe positioning acceleration is the normal running acceleration of the inlet section or the outlet section; t ═ A × Tp/AsetpThe time required for the acceleration to go through the fillet curve to zero.
5. The control method for automatically adjusting the inlet and outlet speed of a cold rolling line according to claim 1, wherein: when the speed difference of the inlet and the outlet of the loop is taken as the positioning speed and the square root curve of the positioning speed is optimized, the method comprises the following steps: the position deviation and the positioning acceleration between the set value and the actual value of the loop positioning are the basis for calculating the loop positioning speed, the theoretical relationship among the position, the speed and the acceleration accords with a classical square root formula, and the calculation formula for obtaining the positioning speed by derivation according to the square root formula is
Figure FDA0003553053810000022
Wherein V is the positioning speed; a. thesetpPositioning acceleration is adopted; Δ S is a position deviation;
when the position deviation is large, the speed curve calculated by the previous formula is smooth and can meet the control requirement, but when the position deviation is small, the speed curve calculated by the previous formula is steep, the speed change is too violent, and the speed curve cannot be directly applied;
When the position deviation is less than delta S', the calculation is not performed by adopting the previous formula, but is performed by adopting a linearization formula
Figure FDA0003553053810000023
Wherein a is the slope of the linearization line; Δ S is less than or equal to Δ S'; Δ S' is two calculation formula position deviation switching points;
according to the squareSelecting an optimal switching point according to the characteristics of the curve
Figure FDA0003553053810000024
Obtain a linearized formula of
Figure FDA0003553053810000025
Wherein, TpAcceleration fillet time;
shift the curve to the right by Δ S′Obtaining a speed curve from zero, namely a square root curve of the optimized positioning speed, considering the influence of the acceleration fillet curve of each section, and calculating the formula as
Figure FDA0003553053810000031
Wherein '+' is an inlet loop/'-' is an outlet loop; SIGN is the SIGN of the position deviation Δ S, 1 is positive, and-1 is negative; st＝Asetp×Tp 2And 6, the acceleration smooth distance.
6. The control method for automatically adjusting the inlet and outlet speed of a cold rolling line according to claim 1, wherein: when the positioning speed is higher than the maximum allowable speed, only monitoring the positioning starting point is carried out, and the specific method comprises the following steps: when the position deviation delta S is larger than a certain value, the calculated total positioning set speed exceeds the upper speed limit of the inlet section or the outlet section, when the position deviation delta S is larger than the upper speed limit, the positioning control still calculates the positioning speed V in real time, and for the inlet loop, the maximum speed V of the inlet section is taken INmaxAnd a total positioning set speed VOUTThe lower value of + V is set as the speed of the inlet section, and for the outlet loop, the maximum speed V of the outlet section is taken outOUTmaxAnd a total positioning set speed VINThe smaller value of + V is set as the velocity of the outlet section.
7. The control method for automatically adjusting the inlet and outlet speed of a cold rolling line according to claim 1, wherein: when the positioning deviation is within the range of the smooth distance of the acceleration fillet, the positioning speed is controlled through a PI regulator, and the specific method comprises the following steps: when the deviation of the loop is extremely small, in order to obtain better control effect, the position control is carried out by adopting a PI controller, and the calculation formula is
Figure FDA0003553053810000032
Wherein '+' is an inlet loop/'-' is an outlet loop; v is the positioning speed; kPIs a proportionality coefficient; delta SnThe position deviation of the period; t is a sampling period; t isiIs the integration time.
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