JPS61243128A - Cooling method for metallic strip in cooling zone of continuous annealing furnace - Google Patents

Abstract

PURPOSE:To attain broad control power for cooling by adjusting the contact length at which a metallic strip contacts with cooling rolls and the number of rolls thereby controlling the contact area. CONSTITUTION:The cooling rolls 7a-7e are attached and detached to and from the metallic strip 1 in the stage of bringing the metallic strip 1 into contact with the rolls 7a-7e and cooling the same, by which the cooling is controlled. More specifically, the winding angle of the metallic strip 1 onto the individual rolls 7a-7e is adjusted in the case of changing the contact length of the strip 1 with the rolls 7a-7e in order to control the strip temp.to a target temp. A suitable number of the rolls 7a-7e are thoroughly detached from the strip 1 when the winding angle attains the limit. The cooling of the strip 1 is thus controlled without stopping the traveling thereof.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a metal strip in a cooling zone of a continuous annealing furnace;
For example, it relates to a method of cooling a copper strip.

(Prior art) When continuously annealing a steel plate, the steel plate is heated and soaked to a temperature above the recrystallization temperature, and then cooled to 400°C at a speed of 70 to 100°C, thereby producing cold rolled steel plates with excellent drawing properties and high tensile strength. It is known that steel plates can be produced.

As a method for performing this cooling at low cost using a interconnected facility, the most excellent method is to bring the steel plate into contact with a cooling roll through which a cooling medium is passed, as shown in Figure 3. 58-230602).

In Fig. 3, 1 is a steel plate that is passed through a group of cooling rolls (7 Todoroki to 7.), 3 is an inlet plate temperature control device installed on both sides of the steel plate 1, and 4 is a plate temperature control device. A control valve that adjusts the flow rate of cooling gas to the device 3, 5 a temperature gauge in the width direction of the steel plate on the inlet side, 6
9 is a non-cooling roll provided on the inlet side of the cooling roll group (7a to 7e), 9 is a non-cooling roll also provided on the exit side, and 10 is an exit side steel plate width direction plate thermometer. The cooling rolls 7m, 7c, and 7 in the cooling roll group can be moved vertically in the figure by cooling roll moving devices 8m, 8c, and 8eK belonging to the respective cooling rolls, and by this movement, the steel plate 1 The contact length between the cooling roll and each cooling roll of the cooling roll group (7a to 7.) can be changed.

12 is a calculator, into which the steel plate temperatures on the inlet and outlet sides measured with a plate thermometer 5°10 are introduced;
From the deviation between these temperatures and the target steel plate temperature, the calculator 12 calculates
Flow control valve 4 and cooling roll moving device 8m=8c,
8. Calculate the control value to be introduced into the control device that controls.

Fig. 4 shows the method of Fig. 3 in which the cooling roll 7 a e 7 e y 7 is moved to the position shown by the broken line in order to change the contact length between the cooling roll and the steel plate in order to obtain the target temperature i4 turns. , shows a lowered state.

In this method, the contact length t is the plate temperature at the entrance to the cooling zone (cooling roll group) Tin % and the plate temperature at the outlet side T. It is a function of the thick plate thickness t and line speed V.

L = / (Tin*Toute!#Ma) For example, the third
As shown in the figure, when the speed is reduced from the state where the sheet is being threaded at the maximum speed specified by the line, as shown in Figure 4,
When lowering the cooling roll 7*v7ee7* to shorten the contact length and increase the speed, the reverse operation is performed.

However, this method has the following two problems.

One of them is that as the contact length is made smaller, the cooling roll and the steel plate slip, so it is not possible to make the contact length extremely small. The problem is that it is not possible to have a wide range of cooling control capabilities. Due to this restriction, the contact angle of one roll is limited to about 15 to 120 degrees, and the controllability is only about 1:1/B. Moreover, in the actual twin, the plate thickness is 0.4 to 2.0 mm and the line speed is about 50 to 300 mpm, so it is 1:1
The controllability of /B was insufficient, and as shown in Table IK, when the speed was reduced to, for example, 59 mpm due to line trouble, it was often impossible to take the arm turn at the target temperature.

7-2: When the winding angle is made small, the non-contact portion between the cold and dynamic roll and the cooling roll becomes longer, resulting in a situation where the target cooling rate cannot be achieved. An example is shown in Table 2, and it can be seen that as a result of reducing the contact angle to ensure a cooling end temperature of 400°C, the cooling rate falls below 70°C/S, which is the lower limit of the target value.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for cooling a metal strip using a group of cooling rolls in a cooling zone of a continuous annealing furnace. It is an object of the present invention to provide a method for cooling a metal strip in a cooling zone of a continuous annealing furnace, which solves the above-mentioned problems when controlling cooling by changing the contact length and achieves a wide range of cooling controllability.

(Means for Solving the Problems) The above object of the present invention is to adjust the contact length of a metal strip to each cooling roll in a cooling zone of a continuous annealing furnace equipped with a group of cooling rolls, and to This is achieved by changing the contact area between the metal strip and the group of cooling rolls by selecting the number of cooling rolls used that are to be in contact with the strip.

In the present invention, the number of cooling rolls to be used that should come into contact with the metal strip is selected by moving the cooling rolls toward and away from the metal strip. In other words, when changing the contact length between the cooling roll and the metal strip in order to set the exit side plate temperature to the target temperature, the winding angle of the metal strip around each cooling roll may cause slippage. When the angle becomes a limit, for example 15' or less, one or more rolls can be completely separated from the strip, and the contact length of the rolls in contact.

That is, the winding angle to the roll is set to be equal to or greater than the slip occurrence limit, and in the opposite case, the number of cooling rolls used is increased. In this case, the winding angles in each roll may be the same or may be different.

According to the present invention, when the number of cooling rolls is 5, the range of the winding angle is from 120° x 5 rolls - 600° to 15° x 1 roll - 1
Can be adjusted up to 5°, control range is 1:1/40
In addition to being noticeably wider, the width of Figure 1 (→, Figure 2 (→
As shown in Figure 2, the number of rolls used is reduced and the non-contact length between the cooling rolls is shortened, making it possible to maintain a high cooling rate at all times.

Table 3 and FIG. 1 show examples of control when line deceleration is performed using the conventional method and the present invention. It is believed that according to the present invention, overcooling can be prevented and the target temperature/4' turn can be maintained. I understand.

Figure 1 (a) shows that when passing a steel plate (0.5 x 1000'') at a lie 7 speed of 300 mpm, the entrance plate temperature was 650.
℃, and the target temperature pattern of outlet plate temperature 400℃,
A state in which the winding angle around the five cooling rolls is 60' is shown. Figure 1 (→ indicates that when the line speed is reduced to 60 mpm, in order to achieve the same target temperature as described above, according to the present invention, the cooling rolls 7m and 7e are brought out of contact with the steel plate, and the cooling rolls 7b and 7d are transferred to the cooling rolls 7b and 7d. The winding angle for the cooling roll 7c is 15°, and the winding angle for the cooling roll 7c is 30'.Thus, even when the line is decelerated, the winding angle for all the cooling rolls is 30' as in the conventional method. When the winding angle is set to 15°, supercooling can be avoided and the target temperature can be reached.
5 (possible)

Next, Table 4 and FIG. 2 show other embodiments of the present invention.

Figure 2: A steel plate (0.7 x 1000111) is threaded at a twin speed of 200 mpm, and in order to achieve the target values of an input plate temperature of 650°C, an exit plate temperature of 400°C, and a cooling rate of 120°C/-, five The case where the winding angle to the cooling roll is 50°C is shown. Figure 2 (b) shows the case where the line speed is 60m.
1. According to the present invention, a cooling roll of 7 m,
7b and 7e are in a non-contact state, and the winding angle to the cooling roll 7d is 25°, and the winding angle to the cooling roll 7 is 50°. In this way, as shown in Table 4, the target high cooling rate of 130°C/s can be secured. In addition, in the case of the conventional method, even if the wrapping angle of all the cooling rolls is set to the minimum limit of 15 degrees, the target cooling rate cannot be obtained because the non-contact length between the cooling rolls is long.

According to the present invention, the method of switching the cooling roll to a state in which it is in contact with the steel plate or in a non-contact state is to temporarily stop the running of the steel plate, push the cooling roll into or away from the steel plate, and then However, with this method, the shape of the steel sheet collapses while the train is stopped, and the fluctuations in the sheet temperature become extremely large, making it impossible to stably manufacture the steel sheet. In order to avoid this problem, it is necessary to perform the switching while the steel plate is running, without stopping the steel plate.To do this, the cooling roll is driven by an electric motor and the steel plate running speed is changed in a non-contact state. It is necessary to rotate the parts at the same circumferential speed and then move them in contact with each other in order to prevent damage to the steel plate.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to obtain a wide range of cooling control capabilities, so when the line speed is reduced, the remarkable effect of ensuring the target temperature pattern and cooling rate is achieved. The industrial benefits of this technology are extremely large.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing another embodiment of the invention, and Figs. 3 and 4 are cooling of a metal strip by a conventional cooling roll group. It is a diagram showing a method. DESCRIPTION OF SYMBOLS 1... Steel plate, 3... Inlet side plate temperature control device, 4... Flow rate control valve, 5... Inlet side steel plate width direction plate thermometer, 6... Uncooled roll, 71-711I...・Cooling roll group, 8
m+8e, 8..." Cooling roll transition mechanism, 9... Non-cooling roll, 10-... Output side steel plate width direction plate thermometer, 11
--Control device, 12--Computer procedure amendment (voluntary) October 18, 1985 Director General of the Japan Patent Office Michibe Uga 1, Indication of the case 1985 Patent Application No. 085102 2, Title of the invention Method for cooling metal strips in the cooling zone of a continuous annealing furnace 3, and its relationship to the amended case Patent applicant: 2-6-3 Otemachi, Chiyoda-ku, Tokyo (665) Nippon Steel Corporation Representative Takeshi 1 ) Yutaka 4, Agent 2-4-1-6 Marunouchi, Chiyoda-ku, Tokyo 100, Detailed explanation of the invention in the specification subject to amendment (1) Page 4 of the specification, lines 11-12 “No. Yo11.6
0. . One of them is when the contact length is small, especially when the line is accelerating or decelerating.
The cooling roll and the steel plate tend to slip, so correct it to ``. (2) Page 10, lines 6-9 “By letting go...
...I will try to increase it. " should be corrected to "Keep the rollers separate and in a non-contact state), and if cooling is insufficient, increase the number of cooling rolls." (8) Same page 15, lines 9-14 “Without stopping the steel plate,
······is necessary. ' shall be corrected as follows.

Claims (2)

[Claims] (1) In the cooling zone of a continuous annealing furnace equipped with a group of cooling rolls, by adjusting the contact length of the metal strip to each cooling roll and selecting the number of cooling rolls to be used that should be in contact with the metal strip. A method for cooling a metal strip in a cooling zone of a continuous annealing furnace, the method comprising adjusting the contact area between the metal strip and a group of cooling rolls. (2) When selecting the cooling roll that should be in contact with the metal strip, either bring the cooling roll in a non-contact state and synchronize it with the running speed of the metal strip and then bring it into contact, or bring it into contact from a contact state to a non-contact state. By bringing
2. A method according to claim 1, which is carried out without stopping the running of the metal strip.