CN103191934A - Forecasting method for loop length of hot continuous rolling mill - Google Patents

Abstract

The invention provides a forecasting method for loop length of a hot continuous rolling mill, which is used for forecasting all loop lengths between racks of hot continuous rolling before strip steel threading. According to the invention, the speed of anti-loop opening or anti-narrowing of the hot continuous rolling mill the loop corresponding to each loop can be obtained through the loop length generated at the moment of strip steel biting and speed drop compensation valve in order to prevent loop opening or loop narrowing, so as to obtain a loop length coefficient. The more is the loop length coefficient close to zero, the more stable threading of the strip steel can be realized, and accordingly, loop opening and narrowing can be avoided.

Description

A kind of hot continuous rolling mill loop cover amount pre-judging method

Technical field

The present invention relates to the control method in a kind of metallurgical process, relate in particular to the control method of kink in the continuous hot-rolling mill.

Background technology

Wearing band is a very important and unmanageable link in the hot continuous rolling operating process.Wear when band, the band steel frame of nipping makes mill load take place to change suddenly, thereby causes the dynamic velocity drop of transmission system.

The kink system of hot continuous rolling is exactly that the cover amount of utilizing this dynamic velocity drop to form plays cover control.At present, the new production line of building all uses positioning accuracy height, the fast Hydraulic Looper of response speed, its structure setting as shown in Figure 1, be provided with loop back roll 4 between upstream frame 1 and the downstream frame 2, the kink angle is C, and the preceding elevation angle is A, and the back elevation angle is B, hydraulic cylinder 6 drives rotating shaft 5 and drives loop back roll 4 motions, thus the tension force of accommodation zone steel 3 between frame.The process that plays cover control is: after frame was stung steel, loop back roll 4 began to lift from original position with certain torque immediately, up to contact zones steel 3, dropped into corresponding control mode then.In the kink control procedure, the kink angle can not be excessive can not be too small.

As shown in Figure 2, curve 1 expression kink angle change curve, curve 2 expression kink tension variation curves.Because when kink control drops into, the milling train dynamic velocity drop is excessive, and it is not enough to impact compensation, the kink angle reaches 38.15 degree when making kink build, final kink angle reaches 46.29 degree, makes the actual angle of kink greater than more than angle on target 23 degree, and continues to surpass 500ms, thereby cause kink control unusual, can produce heap steel accident when serious.

As shown in Figure 3, curve 1 expression kink angle change curve, curve 2 expression kink tension variation curves.Because when kink control dropped into, kink angle too small (14.65deg), its kink tension force were greater than desired value, thereby it is unusual to cause kink to be controlled, make band steel toe portion drawing down, until breaking.

Summary of the invention

The purpose of this invention is to provide a kind of hot continuous rolling mill loop cover amount pre-judging method, it is used for before the band steel is worn band each the kink cover amount between the continuous hot-rolling mill frame being carried out anticipation, thereby make the band steel better to stablize and wear band, avoided cover and drawing down, and then improved the quality of products.

The present invention provides a kind of kink cover amount pre-judging method of continuous hot-rolling mill according to the foregoing invention purpose, and it comprises the following steps:

(1) each kink between definite continuous hot-rolling mill frame is stung the cover amount LOOP1 of steel moment generation at the band steel respectively _j:

${\mathrm{LOOP}1}_j=\frac{1}{2}\·V_{1j}\·t_j---\left(1\right)$

In the formula (1), V _1jWhen stinging steel for the band steel, the speed drop-out value of the continuous hot-rolling mill frame of j kink correspondence (when the band steel was stung steel, gantry speed was impacted, and can cause the decline of gantry speed); t _jAfter being with steel to sting steel, the speed of the continuous hot-rolling mill frame of j kink correspondence returns to the required time of normal value (when the speed of frame drops to a certain degree from the lowest point value, when being the lowest point value, even control system does not compensate gantry speed, its speed also can return to normal value, but the process need regular hour of this recovery, i.e. t _j); J=1,2,3,4,5,6 (continuous hot-rolling mill has seven frames, is provided with a kink between per two adjacent frames, therefore has six kinks); V in this formula _1jAnd t _jAll record by detecting element.

Determine that respectively each kink is in order to have prevented cover or the required cover amount offset LOOP2 of drawing down _j:

$\mathrm{LOOP}{2}_j=\frac{1}{2}\·V_{2j}\·t_j---\left(2\right)$

In the formula (2), V _2jIt is the velocity compensation setting value (just as mentioned before, the speed decline that existing continuous hot-rolling mill takes place when stinging steel in order to compensate milling train often gives milling train a velocity compensation setting value) of j kink correspondence; t _jAfter being with steel to sting steel, the speed of the continuous hot-rolling mill frame of j kink correspondence returns to required time of normal value, j=1,2,3,4,5,6 from the lowest point value;

(2) determine that respectively each kink plays the cover amount LOOP3 of cover or drawing down _j:

LOOP3 _j＝LOOP1 _j-LOOP2 _j (3)

Under the theory state, wish LOOP3 _j=0, so, will be very steady when the band steel is nipped, neither cover can take place, also drawing down can not take place, but LOOP3 can not be 0 under the actual conditions, the continuous hot-rolling mill below therefore need determining according to LOOP3 has been prevented cover or drawing down speed V _3j

When LOOP3＞0, illustrate that the cover amount that cover amount specific rate drop-out value that velocity compensated value produces produces is big, be with steel that drawing down can take place this moment.

When LOOP3＜0, illustrate that the cover amount that cover amount specific rate offset that the speed drop-out value produces produces is big, be with steel that cover can take place this moment.

(3) continuous hot-rolling mill of determining each kink correspondence has respectively been prevented cover or drawing down speed V _3j:

$V_{3j}=\frac{2\mathrm{LOOP}{3}_j}{t_j}---\left(4\right)$

(4) determine the cover coefficient of discharge K of each kink correspondence respectively _j:

$K_j=\frac{V_{3j}\·2\mathrm{\π}\·J\·{\mathrm{\ω}}_c}{60\·4\·1000\·T\·\mathrm{\η}}---\left(5\right)$

In the formula (5), V _3jThe continuous hot-rolling mill that is j kink has been prevented cover or drawing down speed; J is total rotary inertia of milling train and motor; ω _cCut-off frequency for the mill speed control loop; T changes for the milling train load; η is the motor gearratio.Above-mentioned J, ω _c, T, η determine by the build-in attribute of milling train that all according to the difference of milling train, these values are also slightly different, when milling train was determined, these values were also determined, are that the one of ordinary skilled in the art can learn.

(5) according to the cover coefficient of discharge K of each kink correspondence _jThe band stability of wearing to the band steel is carried out anticipation: K _j＜0 shows that cover, K can take place the band steel _j＞0 shows that drawing down can take place the band steel, and K _jIt is more stable more to wear band close to 0 expression band steel.

Obtaining cover coefficient of discharge K _jAfter, control system can be carried out anticipation to the crossing process of being with steel according to step (5), and is more stable for the crossing process that makes the band steel then, need make cover coefficient of discharge K _jClose to 0, also be LOOP3 constantly _jConstantly close to 0, need V so _3jDynamically adjust, and then need be to the velocity compensation setting value V of each kink correspondence _2jDynamically adjust, prevent from being with steel that cover or drawing down have taken place.

Hot continuous rolling mill loop cover amount pre-judging method of the present invention, overlap or the required cover amount offset of drawing down in order to have prevented at cover amount and the kink of being with steel to sting steel moment generation by obtaining kink, the continuous hot-rolling mill that obtains each kink correspondence has been prevented cover or drawing down speed, and then obtain the cover coefficient of discharge of each kink correspondence, thereby the stability that the band steel is about to the crossing process that carries out is judged.Can adjust in advance early according to the result who judges, wear band thereby realize being with steel to stablize, avoid cover and drawing down.

Description of drawings

Fig. 1 arranges schematic diagram for the structure of kink.

Fig. 2 is in the kink control procedure, when a cover angle is excessive, and the change curve of kink angle, kink tension force.

Fig. 3 is in the kink control procedure, when a cover angle is too small, and the change curve of kink angle, kink tension force.

Fig. 4 is the flow chart of hot continuous rolling mill loop cover amount pre-judging method of the present invention.

The specific embodiment

As shown in Figure 4, obtain the cover coefficient of discharge (the band steel is straight carbon steel in the present embodiment, and thickness is 3.0mm) of six kinks on the continuous hot-rolling mill according to the following step:

(1) six kinks between definite continuous hot-rolling mill frame are stung the cover amount LOOP1 of steel moment generation at the band steel respectively _j, result of calculation is referring to table 1:

$\mathrm{LOOP}{1}_j=\frac{1}{2}\·V_{1j}\·t_j---\left(1\right)$

In the formula (1), V _1jWhen stinging steel for the band steel, the speed drop-out value of the continuous hot-rolling mill frame of j kink correspondence (when the band steel was stung steel, gantry speed was impacted, and can cause the decline of gantry speed); t _jAfter being with steel to sting steel, the speed of the continuous hot-rolling mill frame of j kink correspondence returns to the required time of normal value (when the speed of frame drops to a certain degree from the lowest point value, when being the lowest point value, even control system does not compensate gantry speed, its speed also can return to normal value, but the process need regular hour of this recovery, i.e. t _j); J=1,2,3,4,5,6 (continuous hot-rolling mill has seven frames, is provided with a kink between per two adjacent frames, therefore has six kinks); V in this formula _1jAnd t _jAll record by detecting element, it is worth referring to table 1.

Determine that respectively each kink is in order to have prevented cover or the required cover amount offset LOOP2 of drawing down _j, result of calculation is referring to table 1:

$\mathrm{LOOP}{2}_j=\frac{1}{2}\·V_{2j}\·t_j---\left(2\right)$

In the formula (2), V _2jIt is the velocity compensation setting value (just as mentioned before, the speed decline that existing continuous hot-rolling mill takes place when stinging steel in order to compensate milling train often gives milling train a velocity compensation setting value) of j kink correspondence; t _jAfter being with steel to sting steel, the speed of the continuous hot-rolling mill frame of j kink correspondence returns to required time of normal value, j=1,2,3,4,5,6 from the lowest point value;

(2) determine that respectively each kink plays the cover amount LOOP3 of cover or drawing down _j, result of calculation is referring to table 1:

LOOP3 _j＝LOOP1 _j-LOOP2 _j (3)

Under the theory state, wish LOOP3 _j=0, so, will be very steady when the band steel is nipped, neither cover can take place, also drawing down can not take place, but LOOP3 can not be 0 under the actual conditions, the continuous hot-rolling mill below therefore need determining according to LOOP3 has been prevented cover or drawing down speed V _3j

When LOOP3＞0, illustrate that the cover amount that cover amount specific rate drop-out value that velocity compensated value produces produces is big, be with steel that drawing down can take place this moment.

When LOOP3＜0, illustrate that the cover amount that cover amount specific rate offset that the speed drop-out value produces produces is big, be with steel that cover can take place this moment.

(3) continuous hot-rolling mill of determining each kink correspondence has respectively been prevented cover or drawing down speed V _3j, result of calculation is referring to table 1:

$V_{3j}=\frac{2\mathrm{LOOP}{3}_j}{t_j}---\left(4\right)$

(4) determine the cover coefficient of discharge K of each kink correspondence respectively _j:

$K_j=\frac{V_{3j}\·2\mathrm{\π}\·J\·{\mathrm{\ω}}_c}{60\·4\·1000\·T\·\mathrm{\η}}---\left(5\right)$

In the formula (5), V _3jThe continuous hot-rolling mill that is j kink has been prevented cover or drawing down speed; J is total rotary inertia of milling train and motor; ω _cCut-off frequency for the mill speed control loop; T is the milling train load torque; η is the motor gearratio, wherein the cover coefficient of discharge K of the value of each parameter and 1#-6# kink _jReferring to table 1.

Table 1.

(5) the cover coefficient of discharge K that calculates according to table 1 _jCan learn that the band steel crossing process of 1#, 2# kink correspondence is the most stable, and the band steel crossing process of 6# kink correspondence is least stable.Drawing down can take place between F3, the F4 frame and between the F5, F6 frame in the band steel, and the band steel between F4, the F5 frame and between the F6, F7 frame cover can take place.

Be noted that above enumerate only for specific embodiments of the invention, obviously the invention is not restricted to above embodiment, many similar variations are arranged thereupon.If those skilled in the art all should belong to protection scope of the present invention from all distortion that content disclosed by the invention directly derives or associates.

Claims (1)

1. the kink cover amount pre-judging method of a continuous hot-rolling mill is characterized in that, comprises the following steps:

(1) each kink between definite continuous hot-rolling mill frame is stung the cover amount LOOP1 of steel moment generation at the band steel respectively _j:

${\mathrm{LOOP}1}_j=\frac{1}{2}\·V_{1j}\·t_j---\left(1\right)$

In the formula (1), V _1jWhen stinging steel for the band steel, the speed drop-out value of the continuous hot-rolling mill frame of j kink correspondence; t _jAfter being with steel to sting steel, the speed of the continuous hot-rolling mill frame of j kink correspondence returns to required time of normal value, j=1,2,3,4,5,6 from the lowest point value;

Determine that respectively each kink is in order to have prevented cover or the required cover amount offset LOOP2 of drawing down _j:

$\mathrm{LOOP}{2}_j=\frac{1}{2}\·V_{2j}\·t_j---\left(2\right)$

In the formula (2), V _2jIt is the velocity compensation setting value of j kink correspondence; t _jAfter being with steel to sting steel, the speed of the continuous hot-rolling mill frame of j kink correspondence returns to required time of normal value, j=1,2,3,4,5,6 from the lowest point value;

(2) determine that respectively each kink plays the cover amount LOOP3 of cover or drawing down _j:

LOOP3 _j＝LOOP1 _j-LOOP2 _j (3)

(3) continuous hot-rolling mill of determining each kink correspondence has respectively been prevented cover or drawing down speed V _3j:

$V_{3j}=\frac{2\mathrm{LOOP}{3}_j}{t_j}---\left(4\right)$

(4) determine the cover coefficient of discharge K of each kink correspondence respectively _j:

$K_j=\frac{V_{3j}\·2\mathrm{\π}\·J\·{\mathrm{\ω}}_c}{60\·4\·1000\·T\·\mathrm{\η}}---\left(5\right)$

In the formula (5), V _3jThe continuous hot-rolling mill that is j kink has been prevented cover or drawing down speed; J is total rotary inertia of milling train and motor; ω _cCut-off frequency for the mill speed control loop; T changes for the milling train load; η is the motor gearratio.

(5) according to the cover coefficient of discharge K of each kink correspondence _jThe band stability of wearing to the band steel is carried out anticipation: K _j＜0 shows that cover, K can take place the band steel _j＞0 shows that drawing down can take place the band steel, and K _jIt is more stable more to wear band close to 0 expression band steel.

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