CN110961469B - Method and device for controlling stability of strip steel head - Google Patents

Abstract

The invention provides a method and a device for controlling the stability of a strip steel head, wherein the method comprises the following steps: before rolling the strip steel, controlling the loop-lifting torque multiple of loops among the racks to increase to a corresponding preset value, and controlling the angle of each loop among the rear racks to be 20-24 degrees; when the strip steel bites into the current frame, determining the speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame; in the rolling process, acquiring an actual angle of a current loop, and adjusting the speed of an upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees; when the strip steel appears in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame; and controlling the loop gain of each loop between the rear frames to be reduced to a preset value.

Description

Method and device for controlling stability of strip steel head

Technical Field

The invention belongs to the technical field of hot rolling, and particularly relates to a method and a device for controlling the stability of a strip steel head.

Background

In the technical field of hot rolling, the finished thin strip steel products are thin in specification and sensitive to rolling force and load distribution, and the stability of the head of the strip steel is difficult to ensure by the existing rolling method, so that the deviation of the head of the thin strip steel and the probability of scrap steel are continuously increased.

The head of the high-strength thin strip steel is folded and broken due to frequent serious deviation, so that the surface quality of the subsequently rolled strip steel is influenced. Not only causes product degradation, but also increases roller consumption, and steel scrap accidents can occur in serious conditions to influence the operation rate and the yield.

Disclosure of Invention

Aiming at the problems in the prior art, the embodiment of the invention provides a method and a device for controlling the stability of a strip steel head, which are used for solving the technical problems that the stability of the strip steel head cannot be ensured during threading, so that the strip steel head deviates and the working efficiency and the yield are further influenced in the prior art.

The invention provides a method for controlling the stability of a strip steel head, which is applied to a finish rolling machine frame, wherein the finish rolling machine frame comprises the following components: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the method comprises the following steps:

before rolling strip steel, controlling the multiple of the loop-lifting torque of loops among the racks to increase to a corresponding preset value, controlling the angle of each loop among the rear racks to be 20-24 degrees, wherein the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame;

when the strip steel bites into the current frame, determining a speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack;

in the rolling process, acquiring an actual angle of a current loop, and adjusting the speed of an upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees;

when the strip steel appears in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame;

and controlling the loop gain of each loop between the rear frames to be reduced to a preset value.

Optionally, the controlling the multiple of the loop-lifting torque of the loop between the racks to increase to the corresponding preset value includes:

controlling the loop starting torque multiple of a loop between the first rack and the second rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the second rack and the third rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of a loop between the third rack and the fourth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fourth rack and the fifth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fifth rack and the sixth rack to increase by 1 on the basis of an initial value;

and controlling the loop starting torque multiple of the loop between the sixth rack and the seventh rack to increase by 1 on the basis of an initial value.

Optionally, the determining the speed difference value of the current rack according to the dynamic speed reduction value and the tension value of the current rack includes:

acquiring a dynamic speed reduction value of the current rack, and determining a first speed difference value of the current rack according to the dynamic speed reduction value, wherein the first speed difference value is 200% of the dynamic speed reduction value;

acquiring a tension value of the current frame, and searching a corresponding second speed difference value in a preset mapping table according to the tension value, wherein the mapping table is used for representing a corresponding relation between the tension value and the second speed difference value;

and determining a speed difference value of the current rack according to the first speed difference value and the second speed difference value.

Optionally, when the difference between the actual angle and the set angle is 3 to 6, adjusting the speed of the upstream frame corresponding to the current loop comprises:

when the actual angle is larger than the set angle by 3-6 degrees, controlling the speed of an upstream rack corresponding to the current loop to be reduced according to a preset adjusting strategy;

and when the actual angle is smaller than the set angle by 3-6 degrees, controlling the speed of the upstream rack corresponding to the current loop to increase according to a preset adjusting strategy.

Optionally, when the strip steel has a wave shape in the current frame, controlling the roll gap leveling speed of the current frame to increase includes:

when the current frame is the first frame, the second frame or the third frame, controlling the roll gap leveling speed of the current frame to increase by 0.15mm/s on the basis of an initial value;

when the current frame is the fourth frame or the fifth frame, controlling the roll gap leveling speed of the current frame to increase by 0.1mm/s on the basis of an initial value;

and when the current frame is the sixth frame or the seventh frame, controlling the roll gap leveling speed of the current frame to increase by 0.05mm/s on the basis of an initial value.

Optionally, the controlling the loop gain of each loop between the rear frames to be reduced to a preset value includes:

controlling loop gain of a loop between the fourth rack and the fifth rack to be reduced by 0.11 on the basis of an initial value;

controlling a loop gain of a loop between the fifth rack and the sixth rack to be reduced by 0.24 on the basis of an initial value;

and controlling loop gain of a loop between the sixth rack and the seventh rack to be reduced by 0.3 on the basis of an initial value.

The invention also provides a device for controlling the stability of the head of the strip steel, which is applied to a finish rolling stand, wherein the finish rolling stand comprises: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the device comprises:

the first control unit is used for controlling the loop-lifting torque multiple of loops among the racks to be increased to a corresponding preset value before rolling the strip steel, controlling the angles of the loops among the rear racks to be 20-24 degrees, and the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame;

controlling loop gains of loops between the rear frames to be reduced to a preset value;

the second control unit is used for determining a speed difference value of the current rack according to the dynamic speed reduction value and the tension value of the current rack when the strip steel bites into the current rack; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack;

the third control unit is used for acquiring the actual angle of the current loop in the rolling process, and adjusting the speed of the upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees;

and the fourth control unit is used for controlling the roll gap leveling speed of the current frame to increase when the strip steel appears in a wave shape on the current frame, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame.

Optionally, the first control unit is specifically configured to:

controlling the loop starting torque multiple of a loop between the first rack and the second rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the second rack and the third rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of a loop between the third rack and the fourth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fourth rack and the fifth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fifth rack and the sixth rack to increase by 1 on the basis of an initial value;

and controlling the loop starting torque multiple of the loop between the sixth rack and the seventh rack to increase by 1 on the basis of an initial value.

Optionally, the second control unit is specifically configured to:

acquiring a dynamic speed reduction value of the current rack, and determining a first speed difference value of the current rack according to the dynamic speed reduction value, wherein the first speed difference value is 200% of the dynamic speed reduction value;

acquiring a tension value of the current frame, and searching a corresponding second speed difference value in a preset mapping table according to the tension value, wherein the mapping table is used for representing a corresponding relation between the tension value and the second speed difference value;

and determining a speed difference value of the current rack according to the first speed difference value and the second speed difference value.

Optionally, the fourth control unit is specifically configured to:

when the current frame is the first frame, the second frame or the third frame, controlling the roll gap leveling speed of the current frame to increase by 0.15mm/s on the basis of an initial value;

when the current frame is the fourth frame or the fifth frame, controlling the roll gap leveling speed of the current frame to increase by 0.1mm/s on the basis of an initial value;

and when the current frame is the sixth frame or the seventh frame, controlling the roll gap leveling speed of the current frame to increase by 0.05mm/s on the basis of an initial value.

Optionally, the first control unit is further specifically configured to:

the control of loop gain of each loop between the rear frames is reduced to a preset value, and the control method comprises the following steps:

controlling loop gain of a loop between the fourth rack and the fifth rack to be reduced by 0.11 on the basis of an initial value;

controlling a loop gain of a loop between the fifth rack and the sixth rack to be reduced by 0.24 on the basis of an initial value;

and controlling loop gain of a loop between the sixth rack and the seventh rack to be reduced by 0.3 on the basis of an initial value.

The embodiment of the invention provides a method and a device for controlling the stability of a strip steel head, which are applied to a finish rolling stand, wherein the finish rolling stand comprises: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the method comprises the following steps: before rolling strip steel, controlling the multiple of the loop-lifting torque of loops among the racks to increase to a corresponding preset value, controlling the angle of each loop among the rear racks to be 20-24 degrees, wherein the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame; when the strip steel bites into the current frame, determining a speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack; in the rolling process, acquiring an actual angle of a current loop, and adjusting the speed of an upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees; when the strip steel appears in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame; controlling loop gains of loops between the rear frames to be reduced to a preset value; therefore, the loop-lifting torque multiple of the loop among the racks is increased to a corresponding preset value, so that enough tension can be ensured among the racks, and the deviation of the strip steel is prevented; when the strip steel bites into the rack, dynamic speed drop can be generated, and then the dynamic speed drop is compensated by using a speed difference value, so that the stability of the head of the strip steel in the rolling process is improved; further, in order to ensure the stable tension of the head of the strip steel and prevent off-tracking and pack rolling, the speed of an upstream rack corresponding to the current loop needs to be adjusted in real time according to the angle of the loop in the rolling process, so that the loop enters a stable state; in order to stabilize the tension, the repeated periodic oscillation of the loop is avoided, the loop gain of each loop is reduced, and the loops are further in a stable state; in order to adjust the wave shape of the strip steel in time and prevent deviation, the speed of adjusting the roll gap leveling value of the rolling mill is improved; by the processing mechanism, the stability of the head of the strip steel can be improved, the deviation of the head of the strip steel is avoided, and the working efficiency and the yield are improved.

Drawings

FIG. 1 is a schematic flow chart of a method for controlling the stability of a strip steel head according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a device for controlling the stability of a strip steel head according to an embodiment of the present invention.

Detailed Description

In order to solve the technical problems that the stability of the head of the strip steel cannot be ensured during threading in the prior art, so that the head of the strip steel deviates, and further the operation efficiency and the yield are influenced, the invention provides a method and a device for controlling the stability of the head of the strip steel, which are applied to a finish rolling stand, wherein the finish rolling stand comprises: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the method comprises the following steps: before rolling strip steel, controlling the multiple of the loop-lifting torque of loops among the racks to increase to a corresponding preset value, controlling the angle of each loop among the rear racks to be 20-24 degrees, wherein the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame; when the strip steel bites into the current frame, determining a speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack; in the rolling process, acquiring an actual angle of a current loop, and adjusting the speed of an upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees; when the strip steel appears in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame; and controlling the loop gain of each loop between the rear frames to be reduced to a preset value.

The technical solution of the present invention is further described in detail by the accompanying drawings and the specific embodiments.

Example one

The embodiment provides a method for controlling the stability of a strip steel head, which is applied to a finish rolling stand, wherein the finish rolling stand comprises: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; a loop is arranged between the racks, as shown in fig. 1, the method comprises the following steps:

s110, before rolling strip steel, controlling the loop lifting torque multiple of loops among the racks to increase to a corresponding preset value, and controlling the angle of each loop among the rear racks to be 20-24 degrees;

in order to ensure enough tension and sleeve lifting speed among the racks and prevent the strip steel from deviating, the sleeve lifting torque multiple of the loop among the racks is controlled to be increased to a corresponding preset value before the strip steel is rolled.

As an alternative embodiment, controlling the multiple of the loop-pulling torque of the loop between the racks to increase to the corresponding preset value includes:

controlling the loop starting torque multiple of a loop between the first rack and the second rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of the loop between the second rack and the third rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of a loop between the third rack and the fourth rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of the loop between the fourth rack and the fifth rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of the loop between the fifth rack and the sixth rack to increase by 1 on the basis of an initial value; and controlling the loop starting torque multiple of the loop between the sixth rack and the seventh rack to increase by 1 on the basis of an initial value.

Finally, the loop-up torque multiple of the loop between the first rack and the second rack is 4.5, the loop-up torque multiple of the loop between the second rack and the third rack is 4.0, the loop-up torque multiple of the loop between the third rack and the fourth rack is 3.5, the loop-up torque multiple of the loop between the fourth rack and the fifth rack is 3.0, the loop-up torque multiple of the loop between the fifth rack and the sixth rack is 2.5, and the loop-up torque multiple of the loop between the sixth rack and the seventh rack is 2.5.

Meanwhile, in order to observe and adjust the corresponding loop angle within 0.5s in the process of threading the strip steel in time, the angle of each loop between the rear frames is controlled to be 20-24 degrees in the embodiment; the rear frame includes: a fourth frame, a fifth frame, a sixth frame and a seventh frame. Therefore, observation is facilitated, and the phenomena of tension losing and tension control difficulty increase caused by too large angle are avoided.

S111, when the strip steel bites into the current rack, determining a speed difference value of the current rack according to a dynamic speed reduction value and a tension value of the current rack; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack;

the speed of the stand is lower than the preset speed when the strip steel bites the steel in the process of biting the steel, so that dynamic speed drop can be generated, the rolling stability can be influenced in the process, the speed and the speed compensation regulation and control capability of the rolling mill loop control can be influenced, and the stability of the head and the tail of the strip steel can be further influenced.

Therefore, the dynamic deceleration is compensated by using the speed difference value so as to adjust the speed of the current rack and the speed of a rack on the current rack. Specifically, the current frame is controlled to increase the speed, and the previous frame is controlled to decrease the speed. For example, if the speed difference is 1%, the speed increasing amount of the current rack is 0.5%, and the speed decreasing amount of the previous rack is 0.5%.

As an optional embodiment, determining the speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame specifically includes:

acquiring a dynamic speed reduction value of the current rack, and determining a first speed difference value of the current rack according to the dynamic speed reduction value, wherein the first speed difference value is 200% of the dynamic speed reduction value; here, the dynamic deceleration value corresponding to each steel grade can be obtained in advance.

And acquiring a tension value of the current frame, and searching a corresponding second speed difference value in a preset mapping table according to the tension value, wherein the mapping table is used for representing a corresponding relation between the tension value and the second speed difference value. Specifically, a target tension range to which the tension value belongs in a mapping table is determined, and a corresponding speed difference value is determined according to the target tension range;

wherein, the mapping table can be as shown in table 1:

TABLE 1

Actual value of tension	Speed difference value
		150％-160％	1％
160％-170％	2％
		170％-200％	3％
200％-250％	4％
		250％-300％	5％
100％-110％	-1％
		90％-100％	-2％
75％-90％	-3％
		60-75％	-4％
45％-60％	-5％

In table 1, the tension ranges do not include the right end point.

And when the first speed difference value and the second speed difference value are determined, determining the speed difference value of the current rack according to the first speed difference value and the second speed difference value, wherein the speed difference value is the sum of the first speed difference value and the second speed difference value. Wherein the speed difference value of the current rack is (-5%, 5%) of the speed of the current rack.

S112, in the rolling process, acquiring the actual angle of the current loop, and when the difference value between the actual angle and the set angle is 3-6, adjusting the speed of an upstream rack corresponding to the current loop;

in the rolling process, in order to reduce the overshoot and overshoot caused by the coupling of the thickness control AGC roll gap adjustment and the second flow adjustment under automatic control, the periodic fluctuation of the loop is further caused. The method and the device have the advantages that the actual angle of the current loop is obtained in the rolling process, and when the difference value between the actual angle and the set angle is 3-6 degrees, the intervention input of the loop is controlled to adjust the upstream rack speed corresponding to the current loop, so that the rolling mill speed under automatic control is offset, and the loop enters a stable state.

As an optional embodiment, when the difference between the actual angle and the set angle is 3 to 6, adjusting the upstream frame speed corresponding to the current loop comprises:

when the angle of the loop is decreased from a high angle or increased from a low angle, and the actual angle is 3-6 degrees larger than the set angle, controlling the speed of an upstream rack corresponding to the current loop to be decreased according to a preset loop adjusting strategy;

and when the actual angle is smaller than the set angle by 3-6 degrees, controlling the speed of the upstream rack corresponding to the current loop to increase according to a preset loop adjusting strategy. Wherein, the high angle may include: an angle greater than the set angle; the low angles may include: an angle less than the set angle. The set angle is typically 24 °.

For example, when the loop angle is 40 °, the loop angle can be understood as a high-position angle, and once the angle reaches 27 to 30 ° (excluding 27) in the descending process, the speed of the corresponding upstream rack needs to be adjusted according to a loop adjustment strategy.

Specifically, the loop adjustment strategy may be as shown in table 2:

TABLE 2

Angle of the loop	Corresponding loop intervention quantity
		Less than or equal to 15 degrees or the low casing time is more than 2s	2 th gear 2 times
Less than or equal to 15 degrees or the low casing time is more than 1s	2 th gear 1 times negative
		≤19°	1 st gear 1
20°-27°	Without intervention
		≥28°	1 st gear 1
≥35°	2 nd 1 st gear
		≥40°	2 positive gears 2 times
≥45°	Positive 2 shift 3 times
		≥50°	Recommended spent disposal

For example, when the loop angle between the first frame and the second frame is 28 °, the loop needs to be controlled to execute once according to the positive 2 gear, and the speed of the corresponding first frame is reduced.

Wherein, the negative 2 to positive 2 gears in table 2 are loop gear parameters, and the loop gear parameters are 1% of the corresponding frame speed. For example, when executing 2 once, the loop parameter is increased by 3% and the speed of the previous frame is decreased by 3%.

The specific definitions of the loop gear parameters are shown in table 3:

TABLE 3

Loop gear mark	Looper gear name	Loop gear parameter
			2	Positive 2 gear	3％
1	1 st gear	1.5％
			0	Positive 0 gear	Initial position
-1	Minus 1 gear	-1.5％
			-2	Negative 2 gear	-3％

S113, when the band steel is in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame;

in the rolling process, the thin high-strength steel is easy to generate wave shape due to large rolling force, and the off-tracking overlapping rolling and even the scrap steel occur. In order to adjust the wave shape in time and prevent off tracking and steel scrap, work as belted steel is in when the wave shape appears in current frame, control the roll gap leveling speed of current frame increases, according to after the increase the roll gap leveling speed of current frame is right the roll gap leveling value of current frame is adjusted.

As an alternative embodiment, when the strip steel has a wave shape in the current frame, controlling the roll gap leveling speed of the current frame to increase comprises:

when the current frame is the first frame, the second frame or the third frame, controlling the roll gap leveling speed of the current frame to increase by 0.15mm/s on the basis of an initial value;

when the current frame is the fourth frame or the fifth frame, controlling the roll gap leveling speed of the current frame to increase by 0.1mm/s on the basis of an initial value;

and when the current frame is the sixth frame or the seventh frame, controlling the roll gap leveling speed of the current frame to increase by 0.05mm/s on the basis of an initial value.

In this application, the roll gap leveling speed of the first frame, the second frame and the third frame is 0.3mm/s, the roll gap leveling speed of the fourth frame and the fifth frame is 0.25mm/s, and the roll gap leveling speed of the sixth frame and the seventh frame is 0.2 mm/s.

S114, controlling loop gains of loops between the rear frames to be reduced to a preset value;

and the second flow of the strip steel is unbalanced due to the thickness automatic control strategy, and the tension is unstable and the thickness is unstable when the second flow of the strip steel is unbalanced and the weight is unbalanced between the frames, so that the AGC is excessively adjusted, and finally the loop repeatedly and periodically vibrates.

In order to enable the loop to be in a stable state, the method controls the loop gain of each loop between the rear frames to be reduced to a preset value, and specifically comprises the following steps:

controlling loop gain of a loop between the fourth rack and the fifth rack to be reduced by 0.11 on the basis of an initial value;

controlling a loop gain of a loop between the fifth rack and the sixth rack to be reduced by 0.24 on the basis of an initial value;

and controlling loop gain of a loop between the sixth rack and the seventh rack to be reduced by 0.3 on the basis of an initial value.

In this embodiment, the loop gain of the loop between the fourth rack and the fifth rack is 0.69, the loop gain of the loop between the fifth rack and the sixth rack is 0.56, and the loop gain of the loop between the sixth rack and the seventh rack is 0.3.

Therefore, the loop-lifting torque multiple of loops among the racks is increased to a corresponding preset value through the measures, so that enough tension can be ensured among the racks, and the deviation of strip steel is prevented; when the strip steel bites into the rack, dynamic speed drop can be generated, and then the dynamic speed drop is compensated by using a speed difference value, so that the stability of the head of the strip steel in the rolling process is improved; further, in order to ensure the stable tension of the head of the strip steel and prevent off-tracking and pack rolling, the speed of an upstream rack corresponding to the current loop needs to be adjusted in real time according to the angle of the loop in the rolling process, so that the loop enters a stable state; in order to stabilize the tension, the repeated periodic oscillation of the loop is avoided, the loop gain of each loop is reduced, and the loops are further in a stable state; in order to adjust the wave shape of the strip steel in time and prevent deviation, the speed of adjusting the roll gap leveling value of the rolling mill is improved; by the processing mechanism, the stability of the head of the strip steel can be improved, the deviation of the head of the strip steel is avoided, and the working efficiency and the yield are improved.

Based on the same inventive concept, the application also provides a device for controlling the stability of the head of the strip steel, which is detailed in the second embodiment.

Example two

The present application provides a device for controlling strip head stability, as shown in fig. 2, the device comprises: a first control unit 21, a second control unit 22, a third control unit 23, and a fourth control unit 24; wherein,

in order to ensure sufficient tension and sleeve lifting speed between the racks and prevent the strip steel from deviating, the first control unit 21 is used for controlling the sleeve lifting torque multiple of the loop between the racks to be increased to a corresponding preset value before the strip steel is rolled.

As an alternative embodiment, the first control unit 21 controls the loop-pulling torque multiple of the loop between the racks to increase to a corresponding preset value, including:

controlling the loop starting torque multiple of a loop between the first rack and the second rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of the loop between the second rack and the third rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of a loop between the third rack and the fourth rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of the loop between the fourth rack and the fifth rack to increase by 1.5 on the basis of an initial value; controlling the loop starting torque multiple of the loop between the fifth rack and the sixth rack to increase by 1 on the basis of an initial value; and controlling the loop starting torque multiple of the loop between the sixth rack and the seventh rack to increase by 1 on the basis of an initial value.

Finally, the loop-up torque multiple of the loop between the first rack and the second rack is 4.5, the loop-up torque multiple of the loop between the second rack and the third rack is 4.0, the loop-up torque multiple of the loop between the third rack and the fourth rack is 3.5, the loop-up torque multiple of the loop between the fourth rack and the fifth rack is 3.0, the loop-up torque multiple of the loop between the fifth rack and the sixth rack is 2.5, and the loop-up torque multiple of the loop between the sixth rack and the seventh rack is 2.5.

Meanwhile, in order to observe and adjust the corresponding loop angle within 0.5s in the process of threading the strip steel in time, the first control unit 21 is also used for controlling the angles of all loops between the rear frames to be 20-24 degrees; the rear frame includes: a fourth frame, a fifth frame, a sixth frame and a seventh frame. Therefore, observation is facilitated, and the phenomena of tension losing and tension control difficulty increase caused by too large angle are avoided.

In the process of biting the steel of the strip steel, the speed of the rack is lower than the preset speed during biting the steel, so that dynamic speed drop can be generated, the rolling stability can be influenced in the process, the speed and the speed compensation regulation and control capability of the rolling mill loop control can be influenced, and the stability of the head and the tail of the strip steel can be further influenced.

Therefore, the dynamic deceleration is compensated by using the speed difference value so as to adjust the speed of the current rack and the speed of a rack on the current rack. Specifically, the current frame is controlled to increase the speed, and the previous frame is controlled to decrease the speed. For example, if the speed difference is 1%, the speed increasing amount of the current rack is 0.5%, and the speed decreasing amount of the previous rack is 0.5%.

The second control unit 22 is configured to determine a speed difference value of the current stand according to the dynamic speed reduction value and the tension value of the current stand when the strip steel bites into the current stand; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack;

determining a speed difference value of the current rack according to the dynamic speed reduction value and the tension value of the current rack, specifically comprising:

acquiring a dynamic speed reduction value of the current rack, and determining a first speed difference value of the current rack according to the dynamic speed reduction value, wherein the first speed difference value is 200% of the dynamic speed reduction value; here, the dynamic deceleration value corresponding to each steel grade can be obtained in advance.

And acquiring a tension value of the current frame, and searching a corresponding second speed difference value in a preset mapping table according to the tension value, wherein the mapping table is used for representing a corresponding relation between the tension value and the second speed difference value. Specifically, a target tension range to which the tension value belongs in a mapping table is determined, and a corresponding speed difference value is determined according to the target tension range;

wherein, the mapping table can be as shown in table 1:

TABLE 1

Actual value of tension	Speed difference value
		150％-160％	1％
160％-170％	2％
		170％-200％	3％
200％-250％	4％
		250％-300％	5％
100％-110％	-1％
		90％-100％	-2％
75％-90％	-3％
		60-75％	-4％
45％-60％	-5％

In table 1, the tension ranges do not include the right end point.

And when the first speed difference value and the second speed difference value are determined, determining the speed difference value of the current rack according to the first speed difference value and the second speed difference value, wherein the speed difference value is the sum of the first speed difference value and the second speed difference value. Wherein the speed difference value of the current rack is (-5%, 5%) of the speed of the current rack.

In the rolling process, in order to reduce the overshoot and overshoot caused by the coupling of the thickness control AGC roll gap adjustment and the second flow adjustment under automatic control, the periodic fluctuation of the loop is further caused. The method and the device have the advantages that the actual angle of the current loop is obtained in the rolling process, and when the difference value between the actual angle and the set angle is 3-6 degrees, the intervention input of the loop is controlled to adjust the upstream rack speed corresponding to the current loop, so that the rolling mill speed under automatic control is offset, and the loop enters a stable state.

The third control unit 23 is configured to obtain an actual angle of the current loop, and adjust an upstream frame speed corresponding to the current loop when a difference between the actual angle and the set angle is 3-6.

As an optional embodiment, when the difference between the actual angle and the set angle is 3 to 6, adjusting the upstream frame speed corresponding to the current loop comprises:

when the angle of the loop is decreased from a high angle or increased from a low angle, and the actual angle is 3-6 degrees larger than the set angle, controlling the speed of an upstream rack corresponding to the current loop to be decreased according to a preset loop adjusting strategy;

and when the actual angle is smaller than the set angle by 3-6 degrees, controlling the speed of the upstream rack corresponding to the current loop to increase according to a preset loop adjusting strategy. Wherein, the high angle may include: an angle greater than the set angle; the low angles may include: an angle less than the set angle. The set angle is typically 24 °.

For example, when the loop angle is 40 °, the loop angle can be understood as a high-position angle, and once the angle reaches 27 to 30 ° (excluding 27) in the descending process, the speed of the corresponding upstream rack needs to be adjusted according to a loop adjustment strategy.

Specifically, the loop adjustment strategy may be as shown in table 2:

TABLE 2

Angle of the loop	Corresponding loop intervention quantity
		Less than or equal to 15 degrees or the low casing time is more than 2s	2 th gear 2 times
Less than or equal to 15 degrees or the low casing time is more than 1s	2 th gear 1 times negative
		≤19°	1 st gear 1
20°-27°	Without intervention
		≥28°	1 st gear 1
≥35°	2 nd 1 st gear
		≥40°	2 positive gears 2 times
≥45°	Positive 2 shift 3 times
		≥50°	Recommended spent disposal

For example, when the loop angle between the first frame and the second frame is 28 °, the loop needs to be controlled to execute once according to the positive 2 gear, and the speed of the corresponding first frame is reduced.

Wherein, the negative 2 to positive 2 gears in table 2 are loop gear parameters, and the loop gear parameters are 1% of the corresponding frame speed. For example, when executing 2 once, the loop parameter is increased by 3% and the speed of the previous frame is decreased by 3%.

The specific definitions are shown in table 3:

TABLE 3

In the rolling process, the thin high-strength steel is easy to generate wave shape due to large rolling force, and the off-tracking overlapping rolling and even the scrap steel occur. In order to adjust the wave shape in time and prevent off tracking and steel scrap, fourth the control unit 24 is used for being worked as the belted steel is in when the wave shape appears in current frame, control the roll gap leveling speed of current frame increases, according to after the increase the roll gap leveling speed of current frame is right the roll gap leveling value of current frame is adjusted.

As an alternative embodiment, when the strip steel has a wave shape in the current frame, controlling the roll gap leveling speed of the current frame to increase comprises:

when the current frame is the first frame, the second frame or the third frame, controlling the roll gap leveling speed of the current frame to increase by 0.15mm/s on the basis of an initial value;

when the current frame is the fourth frame or the fifth frame, controlling the roll gap leveling speed of the current frame to increase by 0.1mm/s on the basis of an initial value;

and when the current frame is the sixth frame or the seventh frame, controlling the roll gap leveling speed of the current frame to increase by 0.05mm/s on the basis of an initial value.

In this application, the roll gap leveling speed of the first frame, the second frame and the third frame is 0.3mm/s, the roll gap leveling speed of the fourth frame and the fifth frame is 0.25mm/s, and the roll gap leveling speed of the sixth frame and the seventh frame is 0.2 mm/s.

And S114, controlling loop gains of loops among the rear frames to be reduced.

And the second flow of the strip steel is unbalanced due to the thickness automatic control strategy, and the tension is unstable and the thickness is unstable when the second flow of the strip steel is unbalanced and the weight is unbalanced between the frames, so that the AGC is excessively adjusted, and finally the loop repeatedly and periodically vibrates.

In order to make the loop in a steady state, the first control unit 21 of the present application is further configured to:

controlling loop gain of a loop between the fourth rack and the fifth rack to be reduced by 0.11 on the basis of an initial value;

controlling a loop gain of a loop between the fifth rack and the sixth rack to be reduced by 0.24 on the basis of an initial value;

and controlling loop gain of a loop between the sixth rack and the seventh rack to be reduced by 0.3 on the basis of an initial value.

In this embodiment, the loop gain of the loop between the fourth rack and the fifth rack is 0.69, the loop gain of the loop between the fifth rack and the sixth rack is 0.56, and the loop gain of the loop between the sixth rack and the seventh rack is 0.3.

The embodiment of the invention provides a method and a device for controlling the stability of a strip steel head, which are applied to a finish rolling stand, wherein the finish rolling stand comprises: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the method comprises the following steps: before rolling strip steel, controlling the multiple of the loop-lifting torque of loops among the racks to increase to a corresponding preset value, controlling the angle of each loop among the rear racks to be 20-24 degrees, wherein the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame; when the strip steel bites into the current frame, determining a speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack; in the rolling process, acquiring an actual angle of a current loop, and adjusting the speed of an upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees; when the strip steel appears in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame; controlling loop gains of loops between the rear frames to be reduced to a preset value; therefore, the loop-lifting torque multiple of the loop among the racks is increased to a corresponding preset value, so that enough tension can be ensured among the racks, and the deviation of the strip steel is prevented; when the strip steel bites into the rack, dynamic speed drop can be generated, and then the dynamic speed drop is compensated by using a speed difference value, so that the stability of the head of the strip steel in the rolling process is improved; further, in order to ensure the stable tension of the head of the strip steel and prevent off-tracking and pack rolling, the speed of an upstream rack corresponding to the current loop needs to be adjusted in real time according to the angle of the loop in the rolling process, so that the loop enters a stable state; in order to stabilize the tension, the repeated periodic oscillation of the loop is avoided, the loop gain of each loop is reduced, and the loops are further in a stable state; in order to adjust the wave shape of the strip steel in time and prevent deviation, the speed of adjusting the roll gap leveling value of the rolling mill is improved; by the processing mechanism, the stability of the head of the strip steel can be improved, the deviation of the head of the strip steel is avoided, and the working efficiency and the yield are improved.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.

Claims (10)

1. A method for controlling the stability of the head of a strip steel, characterized in that it is applied in a finishing stand comprising: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the method comprises the following steps:

before rolling strip steel, controlling the multiple of the loop-lifting torque of loops among the racks to increase to a corresponding preset value, controlling the angle of each loop among the rear racks to be 20-24 degrees, wherein the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame;

when the strip steel bites into the current frame, determining a speed difference value of the current frame according to the dynamic speed reduction value and the tension value of the current frame; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack;

in the rolling process, acquiring an actual angle of a current loop, and adjusting the speed of an upstream rack corresponding to the current loop when the difference between the actual angle and a set angle is 3-6 degrees;

when the strip steel appears in a wave shape on the current frame, controlling the roll gap leveling speed of the current frame to increase, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame;

and controlling the loop gain of each loop between the rear frames to be reduced to a preset value.

2. The method of claim 1, wherein controlling the loop pull-up torque multiple of the loop between each of the plurality of frames to increase to a corresponding predetermined value comprises:

controlling the loop starting torque multiple of a loop between the first rack and the second rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the second rack and the third rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of a loop between the third rack and the fourth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fourth rack and the fifth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fifth rack and the sixth rack to increase by 1 on the basis of an initial value;

and controlling the loop starting torque multiple of the loop between the sixth rack and the seventh rack to increase by 1 on the basis of an initial value.

3. The method of claim 1, wherein determining the current gantry velocity difference value based on the current gantry dynamic velocity drop value and the tension value comprises:

acquiring a dynamic speed reduction value of the current rack, and determining a first speed difference value of the current rack according to the dynamic speed reduction value, wherein the first speed difference value is 200% of the dynamic speed reduction value;

acquiring a tension value of the current frame, and searching a corresponding second speed difference value in a preset mapping table according to the tension value, wherein the mapping table is used for representing a corresponding relation between the tension value and the second speed difference value;

and determining a speed difference value of the current rack according to the first speed difference value and the second speed difference value.

4. The method of claim 1, wherein said controlling said roll gap leveling speed of said lead frame to increase when said strip exhibits a wave shape at said lead frame comprises:

when the current frame is the first frame, the second frame or the third frame, controlling the roll gap leveling speed of the current frame to increase by 0.15mm/s on the basis of an initial value;

when the current frame is the fourth frame or the fifth frame, controlling the roll gap leveling speed of the current frame to increase by 0.1mm/s on the basis of an initial value;

and when the current frame is the sixth frame or the seventh frame, controlling the roll gap leveling speed of the current frame to increase by 0.05mm/s on the basis of an initial value.

5. The method of claim 1, wherein said controlling a loop gain of each loop between said rear frames to decrease to a predetermined value comprises:

controlling loop gain of a loop between the fourth rack and the fifth rack to be reduced by 0.11 on the basis of an initial value;

controlling a loop gain of a loop between the fifth rack and the sixth rack to be reduced by 0.24 on the basis of an initial value;

and controlling loop gain of a loop between the sixth rack and the seventh rack to be reduced by 0.3 on the basis of an initial value.

6. A device for controlling the stability of the head of a strip steel, characterized in that it is used in a finishing stand comprising: the device comprises a first rack, a second rack, a third rack, a fourth rack, a fifth rack, a sixth rack and a seventh rack; the device comprises:

the first control unit is used for controlling the loop-lifting torque multiple of loops among the racks to be increased to a corresponding preset value before rolling the strip steel, controlling the angles of the loops among the rear racks to be 20-24 degrees, and the rear racks comprise: a fourth frame, a fifth frame, a sixth frame and a seventh frame;

controlling loop gains of loops between the rear frames to be reduced to a preset value;

the second control unit is used for determining a speed difference value of the current rack according to the dynamic speed reduction value and the tension value of the current rack when the strip steel bites into the current rack; the speed difference value is used for adjusting the speed of the current rack and the speed of a rack on the current rack;

the third control unit is used for acquiring the actual angle of the current loop in the rolling process, and adjusting the speed of the upstream rack corresponding to the current loop when the difference between the actual angle and the set angle is 3-6 degrees;

and the fourth control unit is used for controlling the roll gap leveling speed of the current frame to increase when the strip steel appears in a wave shape on the current frame, and adjusting the roll gap leveling value of the current frame according to the increased roll gap leveling speed of the current frame.

7. The apparatus of claim 6, wherein the first control unit is specifically configured to:

controlling the loop starting torque multiple of a loop between the first rack and the second rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the second rack and the third rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of a loop between the third rack and the fourth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fourth rack and the fifth rack to increase by 1.5 on the basis of an initial value;

controlling the loop starting torque multiple of the loop between the fifth rack and the sixth rack to increase by 1 on the basis of an initial value;

and controlling the loop starting torque multiple of the loop between the sixth rack and the seventh rack to increase by 1 on the basis of an initial value.

8. The apparatus of claim 6, wherein the second control unit is specifically configured to:

acquiring a dynamic speed reduction value of the current rack, and determining a first speed difference value of the current rack according to the dynamic speed reduction value, wherein the first speed difference value is 200% of the dynamic speed reduction value;

acquiring a tension value of the current frame, and searching a corresponding second speed difference value in a preset mapping table according to the tension value, wherein the mapping table is used for representing a corresponding relation between the tension value and the second speed difference value;

and determining a speed difference value of the current rack according to the first speed difference value and the second speed difference value.

9. The apparatus of claim 6, wherein the fourth control unit is specifically configured to:

when the current frame is the first frame, the second frame or the third frame, controlling the roll gap leveling speed of the current frame to increase by 0.15mm/s on the basis of an initial value;

when the current frame is the fourth frame or the fifth frame, controlling the roll gap leveling speed of the current frame to increase by 0.1mm/s on the basis of an initial value;

and when the current frame is the sixth frame or the seventh frame, controlling the roll gap leveling speed of the current frame to increase by 0.05mm/s on the basis of an initial value.

10. The apparatus of claim 6, wherein the first control unit is further specifically configured to:

controlling loop gain of a loop between the fourth rack and the fifth rack to be reduced by 0.11 on the basis of an initial value;

controlling a loop gain of a loop between the fifth rack and the sixth rack to be reduced by 0.24 on the basis of an initial value;

and controlling loop gain of a loop between the sixth rack and the seventh rack to be reduced by 0.3 on the basis of an initial value.

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