JPH01152222A - Method for controlling cooling roll speed - Google Patents

Abstract

PURPOSE:To prevent the variations in tension due to thermal contraction and expansion and to stabilize the traveling of a strip by controlling the cooling roll speed based on the temp. difference between the inlet and outlet sides of the metallic strip which is wound on the roll and cooled. CONSTITUTION:The metallic strip 10 heated and soaked in a continuous annealing line is wound on plural cooling rolls 16-1-16-5 through deflector rolls 12 and 14 on the inlet and outlet sides, and cooled. In the cooling, the rotation of the deflector rolls 12 and 14 and cooling roll 16 is controlled by a speed controller 22 through a motor 20 based on a speed command, and the temp. of the strip 10 is controlled by lifting the cooling roll 16 up and down with a cylinder 18. In the control method, the temps. (t) of the strip 10 on the inlet and outlet sides of the cooling roll 16 are measured by a thermometer 30, and a difference between both temps. is obtained. The thermal contraction amt. of expansion amt. is calculated based on the temp. difference. The speed of the cooling roll 16 is then controlled so that the variations in tension due to the contraction or expansion are obviated.

Description

[Detailed description of the invention]

[Industrial Application Field J] The present invention relates to a method for controlling the speed of a cooling roll, and in particular, a heat shrinkable method suitable for controlling the speed of a cooling roll for metal strip in a cooling zone of a continuous annealing furnace. The present invention also relates to a cooling roll speed control method that can prevent tension fluctuations in a metal strip due to thermal expansion. [Prior Art] In continuous annealing lines for metal strips, cooling rolls are widely used to rapidly cool heated metal strips. This cooling roll circulates a cooling liquid inside a hollow roll and winds the strip around the roll while cooling the roll.Many methods have been proposed in this regard (Japanese Patent Application Laid-open No. 118315-1989,
JP-A-57-207126, JP-A-58-96824, etc.). FIG. 2 shows a block diagram of an example of conventional cooling roll speed control. In the figure, 12 is an inlet deflector roll, 14 is an outlet deflector roll, and 16-1 to 16-5 are cooling rolls. The metal strip 10, such as a steel strip, is heated and soaked in the heating zone or soaking zone in the previous stage, and then passed through these cooling rows/1z16-
1 to 16-5, rapidly cooled to a predetermined temperature, and sent to a cooling zone in a subsequent stage. 18-1.18-3.18-5 is a cylinder, by raising and lowering a part of the cooling roll (16-1.16-3.16-5), the metal strip 10 is wound on the cooling roll. The hooks vary in length and control the strip temperature. 2o= , 20-1 to 20-5. 20-0 is the rotational drive motor of each roll, and the rotational speed Vi of each roll, ■
Each speed controller (ASR) 22-i so that 1 to VSs vO matches the speed command value. 22-1 to 22-5.22-0. 24-1.24-3.24-5 is the cooling roll 16-1
．． A cooling roll 16-1.16-3.16, which is a position compensator of 16-3.16-5 and is detected by a position detector 26-1.26-3.26-5 such as a magnetic scale.
-5 position detection signals x1, x3, x5 are input. Also, 28-1.28-3.28-5 is a multiplier,
Cooling roll 16-1.16- measured by a speed detector such as a pilot generator (PLG> not shown)
The rotational speeds V1, v3, v5 of 3.16-5 are multiplied by the output signal from the position compensator 24-1.24-3.24-5, and the speed controller 22-1.22 described above is multiplied by the output signal from the position compensator 24-1.24-3.24-5. -3
．． It is input as a feedback signal to 22-5. In addition, during such feedback control, in order to prevent an adverse effect on the roll of the subsequent stage, for example, the multiplier 28-1
The output signal is doubled and input as a feedback signal to the speed controller 22-2, and this signal is further added to the control system of the cooling roll 16-3 at the subsequent stage. Note that the feedback signal F obtained by adding the output signal of the multiplier 28-5 and the signal accumulated from the previous stage is sent to strip conveyance equipment such as a priddle roll at a further stage, for example.

[Problems to be solved by the invention] However, in the conventional cooling roll speed control method,
There were the following problems. That is, the cooling capacity of the metal strip 10 cooled by the cooling rolls 16-1 to 16-5 is greater than that of the commonly used gas jet cooling, and therefore the temperature of the metal strip 10 rapidly decreases in a short period of time. This will result in a decline. This means that the metal strip 10 undergoes rapid thermal contraction, and therefore the tension in the strip increases, causing the strip to break or warp, resulting in buckling. Furthermore, when the conveying speed of the strip changes or the target cooling temperature changes, the strip thermally expands or contracts, causing tension fluctuations. In the case of thermal expansion, the tension of the strip decreases, resulting in meandering of the strip. On the other hand, as related to the present invention, JP-A-57-23
No. 035 discloses a method in which the cooling roll is moved to control the winding length to a desired length, and at the same time, during the period, the exit speed of the strip after the cooling roll is controlled to keep the tension applied to the strip constant. There is. However, this is to prevent changes in tension when the cooling roll moves, and is not based on temperature differences, so it has not been possible to prevent changes in tension when the temperature changes. OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and provides a cooling roll speed control method that can prevent tension fluctuations due to thermal contraction and thermal expansion of a metal strip. With the goal.

[Means to solve the problem]

In the present invention, when a heated metal strip is cooled while being wound around a plurality of cooling rolls, the temperature difference of the metal strip at the entrance and exit sides of the cooling rolls is determined, and based on the temperature difference, the metal strip is cooled while being wound around a plurality of cooling rolls. The above objective is achieved by calculating the amount of heat shrinkage or thermal expansion of the strip and controlling the speed of the cooling roll so as to suppress tension fluctuations due to the heat shrinkage or thermal expansion.

[Effect]

In the present invention, the amount of thermal contraction or thermal expansion of the metal strip is determined based on the temperature difference between the metal strip at the entrance and exit sides of the cooling roll, and tension fluctuations due to the thermal contraction or thermal expansion are suppressed. In addition, since the speed of the cooling roll is controlled and reflected in the speed 11J 111, it is possible to prevent tension fluctuations due to thermal contraction and thermal expansion of the metal strip, and stable strip threading is possible. [Embodiment 1] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of a speed control device to which the present invention is applied. Components having substantially the same functions as those in FIG. 2 are given the same numbers and explained. Omitted. In this embodiment, in addition to the configuration of the conventional example, thermometers 30-i, 30-1 to 30-4.30 are used to measure the strip temperature ti, j+ to t4, to between each roll.
-0 and the thermometer 30-i, 30-1 to 30-4.30
Each cooling roll 16-1.16- detected by -0
3.16-5 Temperature difference between inlet and outlet (ji-jl
), (tz-t3), and (t4 to io), the amount of thermal contraction (the amount of thermal expansion) of the metal strip 10 is calculated and converted into a speed signal, and the amount of thermal contraction (thermal expansion) of the metal strip 10 is calculated, and the amount is converted into a speed signal. 16
Temperature compensator 32-L32-3.32- inputs signals for correction into multipliers 28-1.28-3.28-5, respectively, in order to reflect the same in the speed control of -5.
5 is provided. For example, the temperature compensator 32-3 includes a thermometer 30-2.
Strip temperatures t2, t3 detected by 30-3
The difference (tz-j3) is input, and based on this, the amount of contraction (expansion m) of the strip between the cooling rolls is calculated using the following formula, and it is converted into a speed signal f(v) for controlling tension fluctuations. , are input to the multiplier 28-3. f(v) −V4/V2 −1−α(tz t3)...(1) Here,
■4 and v2 are the front and rear cooling rolls 16-4.1, respectively.
6-2 rotation speed, α is the coefficient of thermal expansion of the strip. In this way, by controlling the speed in consideration of the shrinkage rate (elongation rate) of the slip due to cooling, etc., it is possible to eliminate tension fluctuations in the strip at the cooling roll portion. In the above embodiment, the thermometers are 30-i and 30-i.
1 to 30-4, 30-o, but only the inlet and outlet thermometers 30-1 and 30-0 were installed, and these detected the inlet and outlet strip temperatures, j
It is also possible to calculate the intermediate temperature based on o. Alternatively, only the inlet side thermometer 30-i may be provided, and the remaining values may be calculated by calculation. Furthermore, it is also possible to calculate the temperature entirely by using the inlet temperature as the soaking temperature in the previous stage without providing any hygrometer. In addition, in the above embodiments, corrections were mainly made for thermal shrinkage in view of the decrease in the temperature of the metal strip, but if the strip conveyance speed changes or the target cooling temperature changes, the strip Even when the material expands thermally, fluctuations in tension due to the thermal expansion can be prevented in the same way. (Effects of the Invention) As explained above, according to the present invention, temperature changes in the strip are taken into consideration when cooling the strip with a cooling roll, so tension fluctuations are eliminated, and strip breakage and buckling are prevented. It is possible to prevent the occurrence of cracks, meandering, etc. It is especially effective for soft materials such as ultra-low carbon steel with a carbon content of 100 ppb or less, high-temperature annealed materials, and ultra-thin materials. have an effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a control device in which the cooling roll speed control method according to the present invention is adopted;
FIG. 2 is a block diagram showing the configuration of an example of a conventional speed control device. 10... Metal strip, 16-1 to 16-5... Cooling roll, 22-t, 22
-1~22-5.22-0...Speed controller (ASR>
, 30-i, 30-1 to 30-4. 30-0... thermometer, jiq jl to t4, to... strip temperature, 3
2-1.32-3.32-5...Temperature compensator.

Claims (1)

[Claims] (1) When cooling a heated metal strip while winding it around multiple cooling rolls, determine the temperature difference of the metal strip at the entrance and exit sides of the cooling rolls, and calculate the temperature difference between the metal strips based on the temperature difference. Calculate the amount of thermal contraction or thermal expansion, and suppress tension fluctuations due to the thermal contraction or expansion.
A cooling roll speed control method comprising controlling the speed of a cooling roll.