JPS6143121B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a speed control device for a continuous rolling mill.
In particular, the present invention relates to a method of controlling a looperless rolling system in a hot finishing mill.

[Background of the invention]

Conventionally, in hot finishing rolling mills, a looper is installed between each stand to control the tension generated between the stands (for example,
No. 32629 "Looper Control Device"). This operating principle is
When the tension applied to the rolling mill fluctuates, the looper position changes to absorb the tension fluctuation. However, tension control using such a looper has the following problems. The first problem is that the looper is in constant contact with the rolled material and is therefore likely to damage the rolled material. In particular, when the looper rises at the start of rolling, it changes from a non-contact state to a contact state, so the rolled material is likely to be damaged at the moment of contact. Soft touch control has been proposed as a countermeasure against this rise, but
Practical implementation is difficult because the loop amount of the rolled material during non-contact must be accurately predicted.

The second problem is maintenance. In other words, it is difficult to maintain the looper against failures, accidents, etc. of the mechanical and electrical elements of the looper. The third problem is that the distance between stands becomes long. In other words, since the looper is installed between the stands, the distance between the stands cannot be made too short. On the other hand, in terms of the quality of the rolled material, it is desirable that the temperature drop during hot rolling be small, and for this purpose, the shorter the distance between the stands, the better. Furthermore, from the point of view of energy saving, if the amount of temperature drop during rolling can be reduced, the set temperature of the heating furnace can be lowered, and from this point of view as well, it is desirable to reduce the distance between the stands. Furthermore, problem 4 is the accuracy of tension detection by the looper. That is, the looper becomes effective only when the rolled material is rolled under a certain tension, but compressive force is sometimes generated during low-tension rolling such as hot rolling, making it impossible to detect tension with the looper at this time. And this is also one of the causes of misrolls.

Further, in the past, roll drive motors in hot finishing mills and the like had poor responsiveness and the motor rotational speed could not be corrected to follow changes in tension, so tension control was performed using a looper. However, with the introduction of technology such as a thyristor control device, recent roll drive motors have become extremely responsive, and the rotational speed of the roll drive motor can now be sufficiently corrected.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems,
The objective is to control the tension between the stands of a continuous finishing rolling mill consisting of a plurality of rolling stands with a configuration without a looper.

[Summary of the invention]

Based on the above-mentioned purpose, this invention eliminates the looper of a hot finishing rolling mill, indirectly detects tension in a non-contact manner using detected values such as motor load torque and rolling force, and based on the detected values. The feature is that the rotational speed of the roll drive motor is controlled by the rotational speed of the roll drive motor.

More specifically, when controlling the front tension of the i-th rolling stand of a continuous rolling mill having multiple rolling stands, the (i-1)th, i, (i+
1) Voltage of the drive motor of the th rolling stand,
The current, speed, and rolling force are detected, and the detected values are used to calculate the rolling torque of each stand, as well as the forward tension and rolling force of each stand, the roll radius, and the rolling torque and rolling force at the standard tension. , the speed of the drive motor of the i-th rolling stand is controlled to maintain the standard tension based on the deviation between the standard tension of the i-th rolling stand and the tension calculated from the relationship between . There is.

[Embodiments of the invention]

Next, specific embodiments of the present invention will be described.

Figure 1 shows an embodiment in which the present invention is applied to a 6-tandem hot finishing rolling mill.
Only the control system for _F8 is shown. In the figure, 1 is a rolled material rolled in the direction of the arrow, 2 is a rolling mill consisting of stands F ₁ to F ₆ , 3 is a motor for driving the roll of the third stand F ₃ of the rolling mill 2 , and 4 is a motor 3 5 is a speed control device, 6 is a current control device that controls the current of the main circuit, 7 is a voltage regulator that controls the terminal voltage of the motor 3, and 8 is a load such as an impact drop. Load compensator for compensating speed changes caused by changes, 9
is the motor load torque (=
The rolling torque G ₁ ) and the rolling force (P ₁ ) of each stand are input from the rolling force detector (e.g. load cell) 11, and the speed setting value of each stand (e.g. ₃ ) is input to maintain the tension between each stand at a predetermined value. A tension control device 10 is a speed ratio adjusting device that adjusts the speed ratio of adjacent stands to prevent the rolled material 1 from forming a loop between the stands. FIG. 1 mainly shows the third stand, and the tension correction amount Δω _3T and the loop correction amount Δω _3L are added to the speed setting value ₃ of the third stand, and the speed target value ω ₃ of the third stand is output. The speed ω _3A detected from the drive motor of the third stand is compared with the adder 32 and input to the speed control device 5 . Here, Δω _3L is a speed ratio compensation amount that is output when a loop occurs. 33 and 34 are adders.

FIG. 2 shows details of the load compensator 8 in FIG. 1. Figure 2 also mainly shows the third stand.

In addition, in FIG. 2, 12 is a voltage regulator 7.
13 is a current detector that detects the current flowing through the motor 3; 14 is a gain adjustment that adjusts the voltage compensation gain in the load compensator 8; 15 is a gain adjuster that adjusts the current compensation gain in the load compensator 8, 16 is a multiplier, and 17 is a function that calculates the reciprocal of the field strength (induced voltage coefficient) ζΦ from the speed signal of the motor 3. The generator 18 is a torque converter that converts the difference between the maximum predicted rolling force P ₃ x and the actual rolling force into a torque signal. FIG. 2 will be explained below.

Maximum predicted value of rolling force P ₃ x before rolling starts
I will give you. Regardless of whether the rolled material 1 is being rolled in a rolling mill or not, the rolling force P ₃ at no load or under load is input from the rolling force detector 11, and the difference ΔP ₃ from the maximum predicted value P ₃ x is converted into torque. 18. The torque converter 18 multiplies this rolling force difference ΔP ₃ by a torque variable coefficient K ₁ , commonly referred to as a torque arm, to obtain a torque deviation Δτ. In other words, Δτ=K ₁・ΔP ₃ ……………(1).

On the other hand, the function generator 17 uses the output signal ω _3A (in the case of F ₃ ) of the speed detector 4 to generate ζΦ ^-1 = K ₂ ω _B (ω _3A ω _B = K ₂ ω _3A (ω _3A > ω _B )... ………(2) is output. However, K ₂ is a constant, ω _B is the base speed (red/sec), and ω _3A is the actual speed (red/sec). Therefore, the torque deviation Δτ and , and the output signal ζΦ ^-1 of the function generator 17 is determined by the multiplier 16, and the value of this product is converted into a voltage value and a current value by the gain adjusters 14 and 15, respectively.Thus, these gain adjustments The output signals of the devices 14 and 15 are transmitted to the speed controller 5 and the current controller 6, respectively.
Correct the output of

Therefore, due to this load compensator 8, the disturbance input to the entire speed control system is always constant because the actual load torque applied to the motor 3 and the load torque calculated from the actual measurement value of the rolling force are offset. ,
The speed of the motor 3 does not change even when there is a sudden change in load, such as an impact drop.

On the other hand, the tension control device 9 in FIG. 1 controls the rolling force P ₁ in the stand during rolling, the current I of the motor 3
_i , the voltage V _i and the speed ω _iA , and calculate the rolling torque. For example, the formula for rolling torque is
-36829 (Japanese Patent Application No. 105071) (8)
Use the formula. Here, I ² R in the first term on the right side of equation (8) and the constant d are omitted, and it is expressed as equation (3).

G _i = A _i V _i I _i /ω _i −A ₂ dω _i /dt−A ₃ ω _i ……
...(3) However, A ₁ , A ₂ , and A ₃ are constants.

The same applies to G _i-1 and G _i+1 . Also, the exit tension (front tension) T of the i-th rolling stand
_i is expressed by taking into account (i-1) and (i+1) the front tension of the stand, following equations (7) and (8) described in Japanese Patent Publication No. 53-43900 (Japanese Patent Application No. 48-66903). , −R _i /P _i T _i-1 + (R _i /P _i +R _i+1 /P _i+1 )T _i −R _i+1 /P _i+1 T _i+1 =(a _i −G _i /P _i )−
(a _i+1 −G _i+1 /P _i+1 )…(4) However, a _i is the rolling torque at the standard tension ( _i )
and rolling force ( _i ), and is calculated from the rolling torque, rolling force, and reference tension when the rolled material 1 is bitten into the i-th stand. By the way, since the above-mentioned tension relational expression (4) holds true for all stands, it can be expressed collectively in matrix form as follows.

PT=G (5) In the above equation (5), PTG represents a vector quantity.

However, P is the coefficient on the left side of equation (4) (roll radius R _i
and rolling force P _i ), T is a vector composed of the tension T _i of each stand, that is, T = (T ₁ , T ₂ , ......, T _o ) ^T ......(6) T on the left side of equation (6) above represents a vector quantity.

The vector G represented by is a vector composed of the values on the right side of equation (4). P and G in equation (5) are both values calculated using the measured rolling force and the measured rolling torque, and by performing the matrix calculation of equation (5), the tension T _i of each stand is T = P ^{- 1}・G ……………(7) In the above equation (7), PTG represents a vector quantity.

It is calculated by The motor speed of each stand is corrected based on the deviation between the tension T _i calculated using equation (7) and the reference tension _i . When the correction amount is Δω _i , Δω _i is calculated using the following equation.

Δω _i =B(T-) ……………(8) However, Δω=(Δω _1T , Δω _ZT , Δω _3T , ~
Δω _o-1 ) ^T and B are influence coefficient matrices.

Although the load compensation device 8 and tension control device 9 described above can control the tension to a predetermined value without forming a loop from the tip of the rolled material, it is conceivable that the motor speed ratio between the stands changes for some reason and a loop is formed. Therefore, in order to perform stable rolling without forming loops, the volume velocity of each stand must be equal. That is, if the thickness of the exit side of the i-stand is h _i , h _i R _i ω _i /G _Ri = h _i+1 R _i+1 ω _i+1 /G
_Ri+1 ......(9) holds true. However, GR _i is the gear ratio.

If it is assumed that the roll radius R in equation (9) is almost the same for all stands, it can be expressed as the following equation (10).

G _Ri+1 /G _Ri・ω _i /ω _i+1 = h _i+1 /
h _i ……………(10) Equation (10) shows that ω _i /ω _i+1 and h _i+1 /h _i are proportional, and if equation (10) always holds true, there will be no loop formation and the system will be stable. Rolling can be performed. However, when ω _i increases, the volume velocities of the i stand and the (i+1) stand are different and a loop is formed. Conversely, when ω _i decreases, a tensile state occurs and excessive tension occurs. A tension control system can detect a tension state, but it cannot detect a loop (tension = 0), so it is necessary to know whether a loop has occurred. Therefore, it is sufficient to monitor whether equation (10) always holds true.

When an excessive loop occurs, if ω _i increases abnormally or ω _i-1 abnormally decreases, the balance will be lost, and equation (10) will not hold and a loop will occur.

FIG. 3 shows the details of the speed ratio control device 10 for an example of a simple loop monitor in this case, with two stands shown for reference. In normal rolling, the reduction ratio is in the range of about 0.7 to 0.95, but when the plate thickness is thin, it takes a value close to 1.0. Therefore, in such a case, it is possible to simply monitor the occurrence of a loop using the following method.

In FIG. 3, reference numeral 19 inputs the speed ω _iA of adjacent stands from the speed detector 4, and the ratio ω _iA /ω _{(i+
1) A divider that outputs A} , 20 inputs the speed ratio ω _iA /ω _(i+1)A from the divider 19 and calculates the left side G _Ri of equation (10).
Constant setter for gear ratio G _{Ri +1} /G _Ri that outputs ₊₁ /G Ri・ω _iA /ω _(i+1)A , 21
is a function generator that outputs a speed correction signal only when the left side of equation (10) is 1 or more.

Thus, inputting the speed of each stand during rolling, G _Ri+1 /G _Ri・ω _iA /ω _(i+1)A is 1
When the speed becomes larger, a speed correction signal Δω _iL is output to the i-th stand.

The embodiments of the present invention have been described above, but the load compensation device 8, tension control device 9,
Each of the speed ratio adjusting devices 10 is just one embodiment, and as a load compensating device, there is a method in which the speed setting value is increased in advance by the amount of speed drop due to the impact drop, or a speed command is issued at the same time as the bite. It is also possible to adopt a method such as raising it in a forming manner. Further, the tension control device may be a method of controlling the current of a roll drive motor. Further, instead of the speed ratio adjusting device, a method may be adopted in which a photoelectric loop detector or the like is used to detect the amount of loop between the stands and adjust the speed ratio.

However, in general, in order to monitor whether or not the above-mentioned formula (10) holds true, the horizontal axis of the function generator shown in FIG. 3 may be set.

As described above, according to the device of the present invention, there is no need to install a loop between the stands, so a thickness meter, a detector such as a shape detector, and a temperature control device such as a sprayer can be installed between the stands. become. In addition, the distance between the stands can be shortened, which reduces the temperature drop in the rolling mill, and also reduces the installation area of the rolling mill, making it economical when installing a rolling mill. The benefits are huge. Furthermore, since impact drops are eliminated, stable rolling can be carried out from the tip of the rolled material, improving yield and quality, and making maintenance of the rolling mill easier. Furthermore, since the loops are removed, the rolled material is not damaged, and the shape of the rolled material is improved.

In other words, in order to eliminate motor impact drops, the current command value or voltage command value of the motor speed control system is corrected to a value greater than or equal to the rolling load applied by the motor before rolling starts, and the rolled material is When the machine is loaded, the actual load is detected from the rolling force and a correction value for current or voltage is subtracted. This eliminates the impact effect of the motor speed and prevents the rolled material from forming loops during biting.

Note that each of the above-mentioned devices can be implemented independently, and can also be implemented by a computer.

〔Effect of the invention〕

According to the present invention, the tension between the stands can be controlled to a desired value without using a looper.

[Brief explanation of the drawing]

FIG. 1 is a system block diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are system block diagrams showing details of each system. Identical members and devices are denoted by the same reference numerals throughout the figures. 1...Rolled material, 2...Rolling machine, 3...Motor,
4...Speed detector, 5...Speed control device, 6...
Current control device, 7... Voltage adjustment device, 8... Load compensation device, 9... Tension control device, 10... Speed ratio adjustment device, 11... Rolling force detector, 12... Thyristor bridge, 13... ...Current detector, 14,1
5...gain adjuster, 16...multiplier, 17,2
1...Function generator, 18...Torque converter.

Claims (1)

[Claims] 1. Multiple rolling stands (1, 2,......(i-
1), i, (i+1)......n), in a control method for controlling the forward tension (T ₁ ) of the i-th stand of a continuous rolling mill having (i-1), i, (i+1), Detecting the voltage, current, speed, and rolling force of the drive motor of the )-th rolling stand, and using the detected voltage, current, and speed to drive the (i-1), i, and (i+1)-th rolling stands. While calculating the rolling torque of the (i-1)th,
i, the deviation between the standard tension of the i-th rolling stand and the calculated tension from the relationship between the forward tension and rolling force of the (i+1)th rolling stand, the roll radius, and the rolling torque and rolling force at the standard tension. calculate the speed correction amount of the i-th rolling stand to maintain the reference tension based on the calculated speed correction amount, correct the reference speed of the i-th rolling stand based on the calculated speed correction amount, and calculate the corrected speed. A control method for a loopless hot finishing continuous rolling mill characterized by controlling the speed so that the following results are obtained.