JPH0436778B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a continuous casting method and continuous casting equipment in which a dummy bar is inserted from above, which is extremely effective particularly when directly connected to a hot rolling line. <Prior art and its problems> In recent continuous casting, for example, there is a method in which slabs cast using curved continuous casting equipment are first made into cold slabs, then reheated in a heating furnace and rolled. However, the casting line and rolling line are directly connected, and the slab after casting is immediately transferred to the rolling line while being kept warm for rolling (direct rolling), or the casting line is directly connected to the rolling line. Methods such as arranging heating equipment to slightly raise the temperature through auxiliary heating and then rolling (direct charge) have been put into practical use from the viewpoint of effectively utilizing the heat of the slab or improving production efficiency. What is important in such continuous casting is to keep the temperature of the slab in the casting equipment as low as possible and to match the process with a hot rolling line with high throughput. In conventional continuous casting, as shown in FIG.
As shown in the figure, there is an independent pulling mode for pulling out the slab after completion of pouring, and the slab guide roll group 3 is the same section that is driven synchronously. Here, the drawing speed of the slab is different between the casting mode and the drawing mode, and the drawing speed of the casting mode is lower than that of the drawing mode from the viewpoint of preventing internal cracking of the slab and prevention of brake out. Therefore, in the conventional method without speed control division,
The next casting cannot be started unless the drawing mode is completed (the final slab passes the outlet side of the pinch rolls). Here, the pulling time in the pulling mode is: Pulling time = machine length (mold to pinch roll exit side)
Expressed as ÷ average pulling speed (in pulling mode), for example, machine length 43 m, average pulling speed
At 1.5m/min, it takes about 29 minutes. In the case of the dummy bar upward insertion method, the time required for preparation work around the mold is shortened to about 10 to 15 minutes, so the preparation time is determined by the drawing time. Therefore, the production efficiency will be reduced by this drawing time. On the other hand, various methods have been proposed in which preceding casting and subsequent casting are carried out continuously (for example,
55-8329, JP 58-157556, JP 57-177865), in any case, the casting speed must be reduced at the initial stage of subsequent casting;
A drop in the temperature of the preceding slab is unavoidable, which is disadvantageous for direct connection with the above-mentioned hot rolling. This invention was proposed in view of the above circumstances, and its purpose is to be able to start casting a trailing slab while the leading slab is being drawn in the normal drawing mode, thereby increasing casting capacity. The object of the present invention is to provide a continuous casting method and continuous casting equipment that can improve the temperature of the preceding slab and prevent the temperature of the preceding slab from decreasing. <Means for Solving the Problems> The continuous casting method according to the present invention divides the slab guide roll group of the continuous casting equipment into a plurality of groups, so that the roll speed of each roll group is independently controlled, 2
By tracking the slab with two slab movement amount detectors, the group of slab guide rolls through which the rear end of the preceding slab that is moving in the drawing mode is changed to the casting mode, and the The casting of the next succeeding slab is started, and the next succeeding slab can be poured while the preceding slab is being drawn in the normal drawing mode. The continuous casting equipment according to the present invention includes a group of slab guide rolls that are divided into a plurality of groups and whose roll speeds are controlled independently, and a group of slab guide rolls that are installed below the mold to detect the amount of movement of the slab during pouring. a casting detector installed on the slab drawing side and capable of detecting the amount of movement of the slab during drawing; and processing the output signals of the casting detector and the pulling detector, and It is equipped with a roll speed control device that controls the roll speed of the group of slab guide rolls, and a casting detector and a withdrawal detector track the slab, and the roll speed control device tracks the slab through which the trailing end of the preceding slab has passed. The one-guide roll group is changed to the casting mode, and the casting of the next trailing slab is started while the leading slab is being drawn.Furthermore, the roll speed control device is used to control the speed of each casting to prevent the dummy bar from colliding with the leading slab. The roll speed of the single guide roll group is adjusted. <Example> The present invention will be described below based on an illustrated example. As shown in FIG. 1, the slab guide roll group 3 consisting of guide rolls or pinch rolls is divided into, for example, four roll groups 3A, 3B, 3C, and 3D which are independently controlled by a roll speed control device 4. . Roll group 3A and roll group 3D below mold 1
A casting detector 5 and a drawing detector 6, which can detect the amount of movement of the slab during casting and drawing, are installed on the outlet side. These detectors 5 and 6 include a pulse generator 5A,
6A and counters 5B and 6B, this movement amount signal is input to an arithmetic unit 7, and tracking of the leading slab _S1 and the trailing slab _S2 is performed. When the rear end of the preceding slab S ₁ passes through each roll group 3A to 3D by this tracking, the roll group is changed from the drawing mode to the casting mode during drawing, and the rear end of the preceding slab S ₁ is detected as a drawing detector. 6, all roll groups 3A to 3D are shifted to the conventional casting mode. Furthermore, in order to prevent the dummy bar 8 and the preceding slab _S1 from colliding, the drawing speed in the casting mode is adjusted so that the distance l between them does not become less than, for example, 50 cm. In tracking, for example, the amount of movement of the preceding slab S ₁ after the rear end of the preceding slab S ₁ passes the casting detector 5 is detected by the drawing detector 6, and the known distance between the detectors 5 and 6 is detected. From the distance, the calculation device 7 detects the detector 6 and the slab S ₁
This is done by finding the distance ΔL from the rear end. The distance l between the dummy bar 8 and the preceding slab S ₁ is also determined in the calculation device 7 as the casting length L ₁ , the dummy bar length L ₀ ,
Calculated from ΔL. The roll speed control device 4 has built-in sequences of a drawing mode, a casting mode during drawing, and a casting mode, and the sequence of the casting mode during drawing during a transition period is as follows. The rear end of slab _S1 passes through roll group 3A → Stops driving roll group 3A ↓ Passes through roll group 3B → Stops driving roll group 3B ↓ Passes through roll group 3C → {Switches to roll group 3C casting mode, roll group 3D pulls out mode Switch to maximum drawing speed In such a mode, roll groups 3A, 3
When the drive of B is stopped, the dummy bar 8 is inserted and the mold sealing work is performed, and the tundish 2 is moved to cast the next trailing slab _S2 . The mold sealing work is a work in which a steel plate frame is placed on the upper end of the dummy bar located directly below the mold, and a sealing material (heat-resistant refractory material) is filled on top of the steel plate frame to seal it with the side wall of the mold. When casting starts, the roll groups 3A and 3B go into the casting mode, and when the preceding slab _S1 leaves the drawing detector 6, all the roll groups go into the casting mode. <Comparative example> Figure 2 shows an example in which low carbon material (C≦0.05%) was cast at an average drawing speed of 1.5 m/min, and as shown in Table 1, the time was reduced by 12 minutes compared to the conventional method. I found out that it can be done. Figure 3 shows medium carbon material (0.10≦C≦0.20
%) at an average drawing speed of 1.0 m/min, and as shown in Table 2, it was found that the time can be reduced by 16 minutes compared to the conventional method. It can be seen that the slower the drawing speed, the greater the shortening effect.

【table】

[Table] <Effects of the Invention> As mentioned above, the continuous casting method according to the present invention divides the slab guide roll group into a plurality of parts and drives them.
The group of rolls through which the rear end of the preceding slab that is moving in the drawing mode changes to the casting mode, making it possible to start the next casting during normal drawing, improving casting capacity and It is possible to prevent the temperature from decreasing, and it can be effectively applied to continuous casting equipment directly connected to hot rolling. Further, the continuous casting equipment according to the present invention can start casting during drawing with a relatively simple configuration.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the continuous casting equipment according to the present invention, Fig. 2 is a graph showing the relationship between the elapsed time from the start of the drawing mode and the slab position, and Fig. 3 is a similar diagram when the drawing speed is changed. 4 is a schematic diagram showing the conventional casting mode, and FIG. 5 is a schematic diagram showing the conventional drawing mode. 1...Mold, 2...Tandatetsuyu, 3
A, 3B, 3C, 3D... Slab guide roll group, 4
... Roll speed control device, 5 ... Casting detector, 6
... Pull-out detector, 5A, 6A ... Pulse generator, 5B, 6B ... Counter, 7 ... Arithmetic device, 8 ... Dummy bar.

Claims (1)

[Scope of Claims] 1. In a continuous casting method employing a dummy bar upward insertion method, the slab guide roll group of the continuous casting equipment is divided into a plurality of groups, and the roll speed of each roll group is independently controlled, By tracking the slab, the slab guide roll group, through which the rear end of the preceding slab moving in the drawing mode has passed, is changed to the casting mode.
A continuous casting method characterized by starting casting of the next succeeding slab during drawing of the preceding slab. 2. Continuous casting equipment that adopts the dummy bar upward insertion method includes a group of slab guide rolls that are divided into multiple groups and whose roll speeds are controlled independently, and a group of slab guide rolls that are installed below the mold to guide the slab that is being poured. a casting detector capable of detecting the amount of movement of the slab; a drawing detector installed on the slab drawing side and capable of detecting the moving amount of the slab during drawing; and output signals of the casting detector and the pulling detector. continuous casting equipment, characterized in that it is equipped with a roll speed control device for controlling the roll speed of each group of slab guide rolls.