Method for controlling the shape of the tail end of a hot rolled strip of different steel grades

Abstract

The present application relates to a kind of different steel grade hot rolling coiling steel strip tail roll shape control method, belong to the control method technical field specially applicable to metal rolling mill.This method first according to historical data statistics the reference table of different steel grade hot rolling strip steel parameter, offset and adjustment quantity, then in actual production, according to the measured real-time rolling center line offset, in reference table, find the historical adjustment quantity of pinch roll two side pressure difference under the same parameter close to real-time rolling center line offset as the real-time adjustment quantity of pinch roll two side pressure difference, calculate the pinch roll two side pressure difference value formed by the real-time adjustment quantity of control pinch roll from the time t when the strip steel reaches pinch roll;Further, according to whether the pressure of the front side guide plate of pinch roll exceeds the preset pressure value and whether the opening amount change of the front side guide plate of pinch roll reaches the set value, the pressure difference value of the two sides of pinch roll is kept or adjusted.The method can avoid the tail layer and overflow edge of strip steel.

Description

Technical Field

[0001] This invention relates to a method for controlling the tail coil shape during hot-rolled strip coiling, particularly a method for controlling the tail coil shape when coiling strips with different tensile strengths in production, and belongs to the technical field of control methods specifically applicable to metal rolling mills. Background Technology

[0002] Coil shape control during hot-rolled strip coiling is a crucial step in hot-rolling production, especially the tail coil shape due to finishing mill roll-off (such as roll-off on the finishing mill F7 stand). Figure 1 As shown, the strip is not under tension control after rolling, which easily leads to misalignment or even overflow edges. Controlling the tail shape of the coiled strip has always been a challenge in coil quality control. In addition, in hot rolling production, steel grades with different specifications and tensile strengths are often rolled on the same hot rolling production line; therefore, the centerline control of hot-rolled strip with different specifications and tensile strengths is also different.

[0003] The side guide plates and pinch rolls at the coiler inlet are the main control devices for the coil shape quality at the tail end of the steel coil. However, currently, the opening of the side guide plates and the pressure deviation on both sides of the pinch rolls are adjusted manually (to make the pinch rolls have different pressure values ​​on both sides). This method of adjusting on-site based on manual experience makes it difficult to ensure that the opening of the side guide plates and pinch rolls is exactly suitable for the coiling of the corresponding steel grade and that the rolling centerline is consistent, thus affecting the tail shape control of the coiled strip. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to prevent misalignment or even overflow at the tail of hot-rolled steel coils of different specifications.

[0005] The technical solution proposed by this invention to solve the above-mentioned technical problems is: a method for controlling the tail coil shape of hot-rolled steel strips of different steel grades, involving a hot-rolling L1 control system, a pinch roll of the coiler, a guide plate on the front side of the pinch roll, and an optical sensor installed in front of the coiler, comprising the following steps:

[0006] 1) Statistical analysis of historical data on the coiling of steel strips of different tensile strengths on the production line. The historical data includes the coiling parameters of hot-rolled strips of different tensile strengths, the historical coiling rolling centerline offset of the hot-rolled strips corresponding to the parameters, and the historical adjustment of the pressure on both sides of the pinch rolls based on the historical coiling rolling centerline offset. The parameters, offsets, and adjustments are compiled into a reference table. The parameters include the tensile strength and thickness of the hot-rolled strips.

[0007] 2) In actual production, the optical sensor measures in real time the offset of the rolling centerline when the strip of a certain steel grade is coiled after finishing rolling and polishing.

[0008] 3) According to the tensile strength of the steel strip, find the historical coiling center line offset of the strip in the reference table, which is close to the real-time rolling center line offset, and find the historical adjustment of the pinch roll pressure difference on both sides corresponding to the historical coiling center line offset of the strip as the real-time adjustment of the pinch roll pressure difference on both sides;

[0009] 4) According to the real-time speed v of the steel strip of the production line and the fixed distance L between the optical sensor and the pinch roll, calculate the time t for the steel strip to reach the pinch roll from the optical sensor, t = L / V;

[0010] 5) Send the real-time adjustment and t to the L1 control system to control the pinch roll to form the pressure difference on both sides of the pinch roll according to the real-time adjustment after t time;

[0011] 6) If the measured pressure of the front side guide plate of the pinch roll does not exceed the preset pressure value, or exceeds the preset pressure value but the change of the opening amount of the front side guide plate of the pinch roll at this time does not reach the set value, the pressure difference on both sides of the pinch roll is not adjusted; if the measured pressure of the front side guide plate of the pinch roll exceeds the preset pressure value and the change of the opening amount of the front side guide plate of the pinch roll at this time reaches the set value, select the maximum historical adjustment of the pinch roll pressure difference on both sides corresponding to the steel grade in the reference table and send it to the L1 control system to control the pinch roll to form the pressure difference on both sides of the pinch roll according to the maximum historical adjustment.

[0012] 7) When the next steel strip to be coiled is the same as the last steel strip to be coiled, the pressure difference on both sides of the pinch roll adjusted according to the last steel strip remains unchanged;

[0013] When the next steel strip to be coiled is not the same as the last steel strip to be coiled, repeat steps 1)-6).

[0014] Further, the preset pressure value is the set value of the front side guide plate pressure of the pinch roll required to maintain the coiling quality of different steels according to a large amount of historical data of the production line; the opening amount set value is the set value of the opening amount change of the front side guide plate of the pinch roll of different thicknesses and widths according to a large amount of historical data of the production line.

[0015] The beneficial effects of the present application are: firstly, according to a large amount of historical data of the production line, parameters of different steel grades, historical coiling rolling center line offset and historical adjustment amount of the pinch roll two-side pressure are obtained to form a reference table, then the parameters of a steel strip in real-time production and the real-time rolling center line offset measured in real time are compared with the reference table, the historical coiling rolling center line offset close to the real-time rolling center line offset under the same parameters is found from the reference table, and the historical adjustment amount of the pinch roll two-side pressure difference corresponding to the historical coiling rolling center line offset is found as the real-time adjustment amount of the pinch roll two-side pressure difference; at the same time, the conveying time t from the real-time measurement position to the pinch roll is calculated, and finally the real-time adjustment amount of the pinch roll two-side pressure difference and the conveying time t are sent to the L1 control system, so that the pinch roll two-side pressure difference is controlled to form the pressure difference value between the two sides of the pinch roll according to the real-time adjustment amount. Then, if the measured pressure of the front side guide plate of the pinch roll does not exceed the preset pressure value, or exceeds the preset pressure value but the opening amount change of the front side guide plate of the pinch roll at this time does not reach the set value, the pressure difference value between the two sides of the pinch roll formed before is maintained; if the measured pressure of the front side guide plate of the pinch roll exceeds the preset pressure value and the opening amount change of the front side guide plate of the pinch roll at this time reaches the set value, the maximum historical adjustment amount of the pinch roll two-side pressure difference corresponding to the steel grade in the reference table is selected to send to the L1 control system, and the pinch roll two-side pressure difference is controlled to form the pressure difference value between the two sides of the pinch roll according to the maximum historical adjustment amount. In this way, on the one hand, the pressure difference value between the two sides of the pinch roll can be adjusted according to the parameter characteristics of each different steel strip, so that the offset of the coiling rolling center line of each different steel strip is not too large when coiling, and on the other hand, when the pressure difference value between the two sides of the pinch roll is not enough, the new pressure difference value between the two sides of the pinch roll is directly formed according to the maximum historical adjustment amount of the pinch roll two-side pressure difference, so as to ensure that the coiling shape of the tail of the strip does not deviate, thereby avoiding tail layering and overflow edge.

[0016] The main function of the existing coiler front guide plate is to guide the strip rolled out of the finishing mill parallel into the coiler and clamp the strip to keep it on the rolling centerline. The coiler side guide plate control mode is divided into two modes: position control and pressure control. However, the two control modes can be converted to each other and mutually protect each other under certain conditions. The main control logic is as follows: After the finishing mill strip is ejected, the coiler side guide plate is in pressure loop control. Its pressure setpoint comes from empirical values ​​set according to the tensile strength and thickness of different steel grades in a reference table. After entering pressure loop control, either the working side or the transmission side is selected for pressure control, while the other side is in position control. The position setpoint is the action amount of one side of the pressure loop. When the side guide plate reaches the set value due to changes in opening amount in pressure control mode, to ensure that the side guide plate does not continue to open or close, causing large misalignment of the strip, the side guide plate will exit pressure loop control and switch to position loop control. The current position is the side guide plate opening value at the moment of jump. If the strip continues to compress the side guide plate at this time, when the side guide plate detection pressure reaches N times the set pressure, the side guide plate will continuously open by 2mm in a 5ms cycle to avoid edge damage to the strip caused by continuous compression, and at the same time control the strip misalignment. The main function of the coiling pinch roll is to use the large diameter difference between the upper and lower pinch rolls to bend and deform the head of the strip, and guide it into the inclined groove between the pinch roll and the auxiliary coiling roll at a certain angle. At the same time, it provides back tension after finishing rolling and maintaining the tension control of the strip. During the coiling process at the tail of the strip, if misalignment or overflow occurs, the pressure difference between the two sides of the pinch roll is adjusted to control the offset of the coil at the tail of the strip, and avoid tail misalignment and overflow. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of hot rolling equipment. Detailed Implementation

[0019] Example

[0020] The coil shape control method for hot-rolled strip steel coils of different steel grades in this embodiment includes the following steps:

[0021] 1) Statistically analyze the historical data of hot-rolled strip steel coiling for different steel grades on the production line. The historical data includes the parameters of hot-rolled strip steel coiling for different steel grades, the historical coiling rolling centerline offset L1 corresponding to the parameters, and the historical adjustment amount of the pressure on both sides of the pinch rolls based on the historical coiling rolling centerline offset. The parameters, offsets, and adjustments are compiled into a reference table. The parameters include the tensile strength and thickness of the hot-rolled strip steel.

[0022] For example, the following table 1 reflects the steel grade parameters of a certain steel grade Q195, the corresponding historical coiling rolling center line offset and the center line offset L1 and the historical coiling rolling center line offset according to the historical coiling rolling center line offset.

[0023] Table 1

[0024]

[0025]

[0026] 2) In actual production, the optical sensor measures the real-time rolling center line offset of the strip steel of a certain steel grade being rolled when coiling after finishing rolling.

[0027] 3) According to the parameters of the strip steel (mainly the tensile strength), find the historical coiling rolling center line offset close to the real-time rolling center line offset measured in step 2) in the reference table established in step 1), and find the historical adjustment amount of the pressure difference on both sides of the pinch roll corresponding to the historical coiling rolling center line offset as the real-time adjustment amount of the pressure difference on both sides of the pinch roll.

[0028] For example, the real-time rolling of the production line in this embodiment is the finished product specification 2.75*1008mm Q195, the tensile strength is 250MPa, the real-time rolling center line offset measured is 85mm, and the historical coiling rolling center line offset close to 85mm is found from table 1 to be 80-100mm, and the historical adjustment amount of the pressure difference on both sides of the pinch roll is found to be 1KN, which is taken as the real-time adjustment amount of the pressure difference on both sides of the pinch roll.

[0029] 4) According to the real-time speed v of the strip steel of the production line and the fixed distance L between the optical sensor and the pinch roll, the time t of the strip steel of the steel grade from the optical sensor to the pinch roll is calculated, t=L / V;

[0030] For example, the real-time rolling of the production line in this embodiment is the finished product specification 2.75*1008mm Q195, the speed is 10m / s, and the distance between the optical sensor and the pinch roll is 10m, so the time t of Q195 from the optical sensor to the pinch roll is t=10 / 10=1s (second).

[0031] 5) The real-time adjustment amount of the pressure difference on both sides of the pinch roll 1KN and t=1s are sent to the L1 control system to control the pinch roll to form the pressure difference value on both sides of the pinch roll according to the real-time adjustment amount of the pressure difference on both sides of the pinch roll 1KN after 1s.

[0032] 6) If the pressure of the front guide plate of the pinch roll does not exceed the preset pressure value, or exceeds the preset pressure value but the change in the opening amount of the front guide plate of the pinch roll at this time does not reach the set value, the pressure value on both sides of the pinch roll is not adjusted.

[0033] The preset pressure value is the pressure setting value of the front side guide plate of the pinch roll required for different steel grades to maintain the quality of the coil according to a large amount of historical data of the production line (see Table 2 below). For example, the preset pressure value of Q195 in the above embodiment is 5 KN according to Table 2.

[0034] Table 2

[0035]

[0036]

[0037] The opening degree setting value is the setting value of the opening degree change of the front side guide plate of the pinch roll according to the historical data of the production line (see Table 3 below). For example, the opening degree setting value of Q195 in the above embodiment is 3 mm according to Table 3.

[0038] Table 3

[0039]

[0040] If the measured pressure of the front side guide plate of the pinch roll exceeds the preset pressure value and the opening degree change of the front side guide plate of the pinch roll reaches the setting value at this time, the maximum historical adjustment amount of the pressure difference between the two sides of the pinch roll corresponding to the steel grade in the above reference table is selected to send to the L1 control system, and the pinch roll is controlled to form the pressure difference value between the two sides of the pinch roll according to the maximum historical adjustment amount. For example, the maximum historical adjustment amount of the pressure difference between the two sides of the pinch roll of Q195 in the above embodiment is 3 KN.

[0041] 7) When the next steel grade coiled strip is the same as the last steel grade coiled strip, the pressure difference between the two sides of the pinch roll adjusted according to the last steel grade is unchanged;

[0042] When the next steel grade coiled strip is not the same as the last steel grade coiled strip, steps 1)-6) are repeated.

Claims

1. A method for controlling the shape of a tail end coil of a steel strip of different steel grades hot rolled, involving a hot rolling L1 control system, pinch rolls of a coiler, a front side guide of the pinch rolls and an optical sensor provided in front of the coiler, characterized in that The method comprises the following steps: 1) Collecting historical data of different tensile strength steel strips during coiling, the historical data including parameters of hot-rolled steel strips of different tensile strength during coiling, historical coiling rolling center line offset of the hot-rolled steel strips corresponding to the parameters and historical adjustment amount of the pressure difference on both sides of the pinch roll according to the historical coiling rolling center line offset, and collecting the parameters, offset and adjustment amount to form a reference table; the parameters include tensile strength and thickness of the hot-rolled steel strips; 2) In actual production, the optical sensor measures the real-time rolling center line offset of the steel strip being rolled during coiling after finishing rolling and strip changing; 3) According to the tensile strength of the steel strip, find the historical coiling rolling center line offset close to the real-time rolling center line offset in the reference table under the same corresponding parameters, and find the historical adjustment amount of the pressure difference on both sides of the pinch roll corresponding to the historical coiling rolling center line offset as the real-time adjustment amount of the pressure difference on both sides of the pinch roll; 4) According to the real-time speed v of the steel strip on the production line and the fixed distance L between the optical sensor and the pinch roll, calculate the time t for the steel strip to reach the pinch roll from the optical sensor, t=L / V; 5) Send the real-time adjustment amount and t to the L1 control system to control the pinch roll to form the pressure difference on both sides of the pinch roll according to the real-time adjustment amount after t time; 6) If the measured pressure of the front guide plate of the pinch roll does not exceed the preset pressure value, or exceeds the preset pressure value but the opening amount change of the front guide plate of the pinch roll at this time does not reach the set value, the pressure difference on both sides of the pinch roll is not adjusted; If the measured pressure of the front guide plate of the pinch roll exceeds the preset pressure value and the opening amount change of the front guide plate of the pinch roll at this time reaches the set value, select the maximum historical adjustment amount of the pressure difference on both sides of the pinch roll corresponding to the steel strip in the reference table and send it to the L1 control system to control the pinch roll to form the pressure difference on both sides of the pinch roll according to the maximum historical adjustment amount; 7) When the next steel strip to be coiled is the same as the last steel strip to be coiled, the pressure difference on both sides of the pinch roll adjusted for the last steel strip remains unchanged; When the next steel strip to be coiled is different from the last steel strip to be coiled, repeat steps 1) to 6).

2. The method of controlling the shape of the tail end of a hot rolled coil of steel of different steel grades according to claim 1, characterized in that: The preset pressure value is the set value of the pressure of the front guide plate of the pinch roll required to maintain the coiling quality of different steel strips according to a large amount of historical data of the production line; and the opening amount set value is the set value of the opening change of the front guide plate of the pinch roll of different thickness and width according to a large amount of historical data of the production line.

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