KR20020047750A - Impact drop compensation apparatus of mill and its compensation method - Google Patents

Abstract

PURPOSE: An apparatus and a method for compensating impact drop of a rolling mill are provided to smoothly carry out rolling operation by minimizing the impact drop of a rolling speed generated by an impact between a rolled strip and work rolls when the rolled strip is entered into the rolling mill. CONSTITUTION: In an impact drop compensation apparatus for minimizing impact drop generated as a strip to be rolled which is rolled to a certain thickness by passing through a plurality of rolling mills is being entered into a rear rolling mill, the apparatus for compensating impact drop is characterized in that generation of loop of the strip to be rolled(1) positioned between the front rolling mill and the rear rolling mill is prevented by lowering a rolling speed of the front rolling mill in the same ratio as a rolling speed lowering ratio of the rear rolling mill when a rolling speed is dropped by impact drop as the strip to be rolled(1) is being entered into the rear rolling mill, wherein the apparatus for compensating the impact drop comprises a first speed correction means(100) outputting a speed correction amount based on a predicted load torch before the strip to be rolled is entered into the rear rolling mill, and slowly reducing a speed correction amount to zero from an entering time point of the strip to be rolled to a recovery time; a second speed correction means(110) obtaining speed deviations per each samples from after the strip to be rolled is entered into a rear stand to a recovery time, and performing speed corrections of a front stand per each sample times as much as the ratios after obtaining ratios of each of the samples to a speed standard value of the rear stand; and addition means(17,120) calculating a speed standard value of an electric motor of the front stand by adding speed correction outputs of the first and second speed correction means(100,110) to an initial speed standard value.

Description

Impact drop compensation apparatus of mill and its compensation method

The present invention relates to an impact drop compensator for minimizing a rolling speed impact drop occurring when a rolled steel sheet enters a rolling mill, and a method of compensating the same, in particular, a mass flow between rolling mills when a rolled steel sheet enters a rolling mill. The present invention relates to an impact drop compensation device and a method for compensating for a drop of a loop by keeping a constant flow.

The steel mill is rolled into a steel plate having a target thickness by passing the hot rolled steel sheet through a plurality of rolling mills to produce a steel sheet having a thickness desired by the consumer or suitable for the next process.

The steel sheet entering the rolling mill proceeds in contact with the working roll of the rolling mill, thereby rolling by the roll gap of the working roll. At this time, the impact occurs as the steel plate and the work roll to proceed in the early stage of the rolling, at this time, the rolling speed is reduced while the rolling speed of the work roll is reduced. In order to secure this point, a rolling speed compensator has been conventionally installed in a rolling mill.

1 is a block diagram showing the configuration of a speed compensator of a rolling mill according to the prior art, Figure 2 is a graph showing the relationship between the actual speed (V) and the time (time) of the work roll at the time of entry of the rolling material 3 is a graph showing the load torque generated in the work roll when the rolled material enters the work roll, and FIG. 4 is a graph showing the trend of the speed compensation amount of the speed compensation calculator according to the prior art.

As shown in Fig. 1, the rolled steel sheet (hereinafter referred to as 'rolling material 1') is rolled in the front end stand i having a work roll 2 and then the rear end stand i + 1. And rolled by the work roll 3 accommodated in the rear end stand i + 1. Here, looking at the drive mechanism of the work roll 3 of the rear-end stand i + 1, the work roll 3 is driven by the electric motor 8 via the gear 5. And the speed control apparatus 10 is installed in order to control the speed of the electric motor 8. At this time, the speed reference value V _REF0 determined by the initial setting calculation and the speed correction amount ΔV calculated by the speed correction calculator 15 are added by the adder 17 as the speed reference value V _REF as an input of the speed control device 10. Applied to the speed controller 10. Therefore, the speed control device 10 controls feedback so that the speed of the motor 8 becomes the speed reference value V _REF value.

Here, when a difference occurs in the exit rolling material 1 speed of the work roll 2 and the entrance rolling material 1 speed of the work roll 3, the work roll 2 and the rear end stand of the front end stand (i) ( Tension or compressive force is generated in the rolling material 1 between the work rolls 3 of i + 1, that is, the rolling material 1 between the stands i, i + 1. In particular, when the rolling material 1 enters the work roll 3, since the work roll 3 is subjected to a considerable load, the rotational speed of the work roll 3 decreases instantaneously.

On the other hand, as shown in FIG. 2, at the time of t1, when the rolling material 1 enters the work roll 3, the speed of the work roll 3 will fall. However, since the work roll 3 is controlled by the speed control apparatus 10, it recovers to the speed reference value _VREF at the time of t2 which is after time of (DELTA) T.

In this case, the recovery time ΔT depends on the speed control response of the motor. Since there is a speed drop in the work roll 3 during the time of ΔT, a compressive force is generated in the rolled material 1 between the work rolls 2 and 3 of the front and rear stands i, i + 1, and thus the occurrence of loops. The more severe the loop, the greater the risk of rolling interruption. In addition, when a compressive force is generated in the rolled material 1, the thickness of the rolled material 1 between the work rolls 2 and 3 becomes thick.

As shown in FIG. 3, when the rolled material 1 enters the work roll 3, the load torque T _L increases in a step shape. In this case, the motor generating torque T _M increases slightly with a phase delay than the load torque T _L , which causes the speed controller 10 to generate a motor generating torque T _M equal to the load torque T _L , but the step It does not become a shape and changes to the same shape as the dashed-dotted line in FIG. 4 because T _L and T _M become equal at the time t2 after the time ΔT has elapsed from the time t1. The reduction phenomenon of the rolling speed described so far is called an impact drop.

In the prior art, the speed compensation calculation device 15 is generally installed to prevent the compressive force from occurring in the rolled material due to such impact drop, in which the rolled material 1 enters each stand. At the same time, the increase in the rolling load is detected from the rolling load detector 13 and operated as a starting point, and the speed compensation amount ΔV is output along the speed pattern as shown in FIG.

Next, a description will be given of a calculation method of the speed compensation operation apparatus according to the prior art.

The speed compensation calculation device predicts and calculates the load torque T _{L at the time} of entering the rolling material by the formula or model equation as in Equation (1).

Where _a is the torque arm (rolling load to load torque proportional coefficient) coefficient, P is the rolling load, and L _d is the length of the contact arc between the work roll and the rolled material.

With respect to the calculated load torque T _L , the speed compensation amount ΔV ₀ at the time of entering the rolling material is calculated as in Equation 2 below.

Where J is the moment of inertia of the motor (= GD2) and w _c is the speed control response of the motor.

In addition, the speed correction calculator calculates the load response time (hereinafter referred to as 'recovery time') ΔT by Equation 3.

Here, K ₁ is a constant.

As shown in FIG. 4, the speed compensation operating device 15 outputs the speed compensation amount ΔV ₀ of Equation 2 as the speed compensation amount ΔV until the rolling material entry time t1, so that The speed is made higher than the initial speed reference value V _REF so that the compressive force of the rolling agent is not generated. The speed compensation amount ΔV is output in such a manner that the speed compensation amount ΔV ₀ is gradually reduced to ₀ until the time of recovery after the entry of the rolled material. That is, from the time t1 to the time t2, the velocity correction amount ΔV is gradually reduced to zero, thereby eliminating the impact drop.

However, in the speed compensator of the rolling mill according to the related art described above, the load torque T _L obtained by Equation 1 is a torque value with respect to the initial speed reference value V _REF0 , and as shown in FIG. 3, the motor is generated during the impact drop time. This does not match the torque T _M , which causes the speed error. In addition, whether the variables used in Equation 1 and the measurement precision affect the speed setting. Therefore, it is impossible to completely remove the impact drop only with the above-described speed correction amount ΔV.

Some patents have been published to supplement the algorithm of the insecure speed compensation arithmetic unit.

In Japanese Laid-Open Patent Publication No. 7-245976 (Invention Name: Speed Compensator of Rolling Mill), an algorithm is started in synchronization with a rolling load signal generated when a rolled material enters a work roll and uses three speed compensation quantities. The first speed compensation operation term obtains the speed compensation value ΔV ₀ and the recovery time ΔT in the same manner as the conventional method, and outputs ΔV ₀ as the speed compensation amount ΔV until the rolling material enters the time t1 and enters the rolling material. Afterwards, the speed compensation amount ΔV ₀ is gradually decreased to _zero until the time of recovery. The second speed compensation calculation term extracts the speed difference at the time of the previous rolling every sampling time and outputs it as the speed compensation amount ΔV1 when the rolling schedule of the current ash and the previous ash are the same. The third speed compensation calculation term is a plate thickness correction term, which is calculated based on the output of the plate thickness detector installed between the stands, and stored after calculating the deviation from the plate thickness reference value. The memory value is converted into the speed compensation amount ΔV2 and output. The final speed reference value V _REF is determined as shown in Equation 4.

"Japanese Patent Laid-Open No. 9-239418 (Invention Name: Speed Compensation Computing Device for Continuous Rolling Mill)" has the same structure as that proposed in "Japanese Patent Laid-Open Publication No. 7-245976 (Name of invention: Speed compensator for rolling mill)". Is used, but the calculation method of the second speed compensation operation term is different. In other words, "Japanese Laid-Open Patent Publication No. 7-245976 (Invention Name: Speed Compensator of Rolling Mill)" measures the speed difference at the time of the last rolling when the rolling schedule of the current ash and the previous ash are the same. The sample was extracted at each sampling time and output as a speed correction amount ΔV1. However, in Japanese Laid-Open Patent Publication No. 9-239418, when the rolling schedule of this ash and the previous ash is the same, the rolled material is placed on the shear stand (i). The maximum deviation ΔV _{ACTX, i} from the speed reference value during the speed recovery time from entry is obtained and then the speed correction coefficient (Kx = ΔV _{ACTX, i} / V _{REF1, i} ) of the front stand ( _i ) is obtained. This value is determined by the speed compensation amounts ΔV1 = V _{REF1 and I + 1} · Kx of the rear stand i + 1 under the assumption that the characteristics of the rolling speed drop of each stand are the same.

Although the Japanese patents considerably improve the conventional method, they have the following problems. In Japanese Laid-Open Patent Publication No. 7-245976, the speed difference is stored in the memory device for the same rolling schedule as when ΔV1 is obtained, and the output is synchronized with the increase of the rolling load during the current speed compensation. I choose. The assumptions to be made prior to performing this algorithm are performed under the assumption that the impact drop characteristics will be the same at the same rolling schedule. However, in practice, the assumption that the previous rolling state and the current rolling state are not completely the same due to the manual intervention of the driver, the temperature characteristics of the rolling material, and other disturbances, does not generally satisfy the assumption that the same speed drop characteristics are exhibited.

Also, in the Japanese Laid-Open Patent Publication No. 9-239418, when ΔV1 is obtained, the speed correction coefficient Kx is obtained using the maximum speed drop of the front end stand (i) and applied to the rear end stand (i + 1). For the same reasons as stated above, it is practically difficult to satisfy the assumption that the two stands have the same dynamic characteristics.

The present invention is provided to solve the problems of the prior art as described above, when the rolling material enters the rear end stand and the rolling speed of the rolling mill temporarily decreases accordingly, the rolling speed of the front stand is lowered according to the rolling speed of the rear end stand. It is an object of the present invention to provide an impact drop compensator and a method of compensating the rolling mill to prevent the occurrence of loops in a rolling material positioned between two stands by changing the ratio to the same ratio.

1 is a block diagram showing the configuration of a speed compensation device of a rolling mill according to the prior art,

2 is a graph showing the relationship between the measured speed (V) and the time (time) of the work roll at the time of entry of the rolled material;

3 is a graph showing the load torque generated in the work roll when the rolled material enters the work roll,

Figure 4 is a graph showing the trend of the speed compensation amount of the speed compensation operation apparatus according to the prior art,

5 is a conceptual diagram of an impact drop compensation device of a rolling mill according to an embodiment of the present invention.

♠ Explanation of symbols on the main parts of the drawing ♠

1: rolled material 2, 3: working roll

5, 5i: gear 8, 8i: motor

10, 10i: Speed control device 15, 15i: Speed compensation operation device

17, 120: adder 20: speed detector

30: speed difference calculator 40: divider

50: speed compensation amount output device 100: first speed correction means

110: second speed correction means

According to the present invention for achieving the object as described above, when the rolling material is passed through a plurality of rolling mills rolled to a predetermined thickness enters the after rolling mill, the rolling speed decrease of the after rolling mill when the rolling speed decreases due to the impact drop phenomenon An impact drop compensation device for slowing the rolling speed of the shear rolling mill at a ratio equal to the ratio is provided to prevent the occurrence of loops of the rolling material located between the shear rolling mill and the rear rolling mill.

In addition, the impact drop compensation device of the present invention outputs the speed compensation amount based on the predicted load torque until the rolling material enters the post rolling mill, and gradually decreases the speed compensation output to 0 from the time of entry of the rolling material to the recovery time. After the first speed correction means and the rolled material enters the rear end stand, the speed deviation is obtained for every sample from the time of recovery to the recovery time, and the rate of the front stand is as much as the ratio after calculating the ratio of each sample to the speed reference value of the rear end stand. Second speed correction means for correcting every sample time, and adding means for adding the speed correction amount output of each of the first and second speed correction means to an initial speed reference value to make the speed reference value of the electric motor of the front end stand.

In addition, according to the present invention, in the impact drop compensation method for compensating for the impact drop generated when the rolled material rolled to a predetermined thickness passing through a plurality of rolling mills enter the rear-end rolling mill, the point of time when the rolling material enters the rear-end rolling mill A first speed compensation step of gradually reducing the speed compensation amount output from 0 to a recovery point; and obtaining a speed deviation for each sample from the time when the rolled material enters the rear stand to the recovery time, and extracting each sample of the rear stand. After the ratio with the speed reference value is obtained, the second speed correction step of correcting the speed of the front end stand for each sample time by the ratio, and the output of each speed compensation amount in the first and second speed correction steps are initially determined. Rolling speed of the shear stand by adding it to the speed reference value of the motor of the shear stand. An impact drop compensation method is provided that includes controlling a degree.

In the following, with reference to the accompanying drawings, a preferred embodiment of the impact drop compensation device and the compensation method of the rolling mill according to the present invention will be described in detail.

The impact drop compensation device proposed in the present invention outputs the speed compensation amount based on the predicted load torque until the rolling material 1 enters, and gradually reduces the speed compensation amount output to 0 from the entry point of the rolling material 1 to the recovery time. After the first speed correction means 100 and the rolled material 1 enter the rear end stand i + 1 and recover the recovery time, the speed deviation is calculated for each sample, and the ratio is compared with the speed reference value of the rear end stand i + 1. The speed compensation amount output of each of the second speed correction means 110 and the first and second speed correction means 100, 110 for correcting the speed of the front end stand i every sample time after An adder 120 is added to the initial speed reference value to make the speed reference value of the electric motor 8i.

[Example]

5 is a conceptual diagram of an impact drop compensation device of a rolling mill according to an embodiment of the present invention.

As shown in Fig. 5, the rear end stand i + 1 is provided with a load detector 13 for detecting the rolling load, and the rolling load detected by the load detector 13 is transferred to the speed compensation operation device 15. Is entered. Then, the speed controller 10 adds the speed reference value _{VREF0, i + 1} determined by the initial setting calculation and the speed compensation amount ΔV _{i + 1} calculated by the speed compensation calculator 15 in the first adder 17. It is applied to the speed controller 10 as the speed reference value V _{REF, i + 1} . Accordingly, the speed controller 10 drives the motor 8 so that the speed of the motor 8 becomes the speed reference value _{VREF, i + 1} . At this time, the speed detector 20 of the rear stage stand i + 1 detects the speed of the electric motor 8 of the rear stage stand i + 1. Then, the speed of the electric motor 8 detected from the speed detector 20 is input to the second speed correction means 110.

The second speed correction means 110 calculates a difference between the speed reference value V _{REF0, i + 1} calculated by the first adder 17 and the speed V _{i + 1} of the motor 8 detected by the speed detector 20. Output of the speed difference calculating device 30 for each sample time until the recovery time ΔT has elapsed from the increase in the load signal P of the speed difference calculating device 30 and the load detector 13 of the rear stage stand i + 1. When the recovery time ΔT elapses from the increase of the load signal P of the load detector 13 by receiving the output of the divider 40 and the divider 40 which performs the operation of dividing the speed reference value V _{REF, i + 1} by. And a speed compensation amount output device 50 for outputting the result as the speed compensation amount ΔV _{dimp, i} at every sample time until gradually decreasing from the final speed compensation value at the time ΔT time from the time point ΔT.

The speed compensation amount ΔV _{dimp, i} from the speed compensation amount output device 50 is output from the speed compensation amount calculation device 15i of the front end stand i by the second adder 120 which controls the rolling speed of the front end stand i. ΔV _{, i} and the speed reference value _{VREF0, i} of the front end stand _i are added to the speed reference value of the speed control device 10i of the front end stand i for controlling the speed of the front end stand i.

Therefore, in the present invention, when the rolling material 1 enters the rear end stand i + 1, the load detector 13 detects the entry of the rolling material 1, and outputs the speed compensation amount of the rear end stand i + 1. The speed correction amount ΔV _{dimp, i} output from the device 50 is not applied to the rear stand (i + 1), and the rolling material whose speed is corrected in the front stand (i) and enters the rear stand (i + 1) is the front stand. This prevents looping between (i) and the rear stand (i + 1).

As described in detail above, the rolling speed impact drop compensator and the compensation method thereof according to the present invention provide a rolling speed of the shear stand so that a loop does not occur in the rolled material positioned between the front end stand and the rear end stand when the rolled material enters the rear end stand. By delaying, there is an advantage in that it is possible to prevent the rolling interruption accident that may be caused by the loop of the rolling material in advance.

The impact drop compensation device of the rolling mill of the present invention and the compensation method thereof, as in the problem of the other patents introduced above, even if the rolling schedule of this ash and the previous ash is not the same, even if the steel sheet size Even if the characteristics of each rolling stand are different, the impact drop phenomenon can be effectively prevented without any treatment. This is because the rolling speed of the shear stand is controlled based on the measured speed and no memory device as in the other patent is required. Therefore, the impact drop phenomenon can be prevented even by rolling various types of rolled materials, and there is an advantage in that the structure is simple because there is no memory device.

Although the technical idea of the impact drop compensator and the compensation method of the rolling mill of the present invention has been described in conjunction with the accompanying drawings, which is illustrative of the best embodiment of the present invention by way of example and not limitation. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (3)

In the impact drop compensation device for minimizing the impact drop phenomenon that occurs when the rolled material rolled to a predetermined thickness through a plurality of rolling mill enters the post rolling mill, When the rolling material enters the post rolling mill and the rolling speed decreases due to the impact drop phenomenon, the rolling speed of the shear rolling mill is slowed down at the same rate as that of the rear rolling mill to reduce the rolling speed. Impact drop compensation device, characterized in that to prevent the loop of the rolled material. The method of claim 1, The impact drop compensation device outputs a speed compensation amount based on a predicted load torque until the rolling material enters a post rolling mill, and firstly speed-compensates the speed compensation amount output to 0 gradually from the time of entry of the rolling material to the recovery time. Sudan, After the rolling material enters the rear end stand, the speed deviation is obtained for every sample from the time of recovery to the recovery time, and the rate compensation of the front end stand is performed every sample time by the ratio after calculating the ratio of each sample to the speed reference value of the rear end stand. 2 speed correction means, And an adding means for adding the speed compensation amount output of each of the first and second speed compensation means to an initial speed reference value to make the speed reference value of the electric motor of the front end stand. In the method for compensating for the impact drop that occurs when the rolled material rolled to a predetermined thickness through a plurality of rolling mill enters the post rolling mill, A first speed compensation step of gradually reducing the speed compensation amount output to 0 from the time when the rolled material enters the post rolling mill and to the recovery point; Obtaining a speed deviation for each sample from the time the rolled material enters the rear stage to the recovery time; A second speed correction step of correcting the speed of the front end stand for each sample time by the ratio after obtaining a ratio of the speed reference value of the rear end stand of each sample; And controlling the rolling speed of the shear stand by adding the respective speed compensation outputs in the first and second speed correction steps to an initial speed reference value and setting the speed reference value of the electric motor of the shear stand. Drop Compensation Method.