JPS58173005A - Endless rolling method - Google Patents

Abstract

PURPOSE:To synchronize a continuous casting machine and a rolling mill by connecting the continuous casting machine and the continuous hot rolling mill through a looper and a soaking pit thereby controlling the transfer speed and soaking temp. of an ingot. CONSTITUTION:An ingot 4 is curved to elongate or contract the length thereof between pinch rolls 6 and 6a provided behind a continuous casting machine so as to eliminate the difference between the casting speed and the rolling speed. Pulse transmitters 25, 25 are attached to the rolls 6, 6a on the inlet and outlet sides of a looper 13 and the casting speeds in the respective pinch roll parts are detected. A synchronous control device 23 controls the speed of the pinch rolls on the outlet side of the looper and the rolling speed when inputted therein with the change in a meniscus level or the speed of the pinch rolls on the outlet side of the looper. A soaking pit 14 soaks the ingot 4 by the recuperation heat from the inside and the surface temp. thereof is measured with a thermometer 24 and is commanded to a control device 21 for continuous casting. The device 21 controls cooling in such a way that the most adequate rolling temp. is attained on the outlet side of the soaking pit in accordance with a command.

Description

Detailed Description of the Invention The present invention relates to an endless rolling method in which a continuous casting machine and a continuous hot rolling mill are directly connected, and an endless rolling method for steel billets with relatively small cross sections such as plumes, billets, strips, and sheet bars. Regarding.

Conventionally, as shown in FIG. 1, a steel billet cast in a continuous casting machine was cut into predetermined lengths using a shearing machine or a gas torch, and then heated and rolled in a heating furnace.

In the continuous casting machine, molten steel in a ladle 1 is injected into a mold 3 through a tundish (1) 2, where the outer peripheral surface is cooled and solidified into a steel billet 4. Continuous casting is performed while adjusting the amount of injection from the tundish and the withdrawal speed of the cooling zone so that the meniscus level within the mold 3 is constant.

Before reaching the cutting position 5, the steel billet 4 is charged into the interior, heated and soaked, and then rolled in a rolling mill. For example, in the case of steel bar rolling, the steel bar is processed through the following steps: rough rolling, crop shearing, intermediate rolling, crop shearing, and finishing rolling.

In the conventional method described above, when cutting a steel billet, the steel billet is cooled so that it hardens to the inside, so the temperature of the steel billet decreases7, and reheating is required during rolling. It's a trench, and since it is rolled with a steel billet, the loss due to the cutting of the end crop is a dog.

The present invention solves the above-mentioned drawbacks, directly connects a continuous casting machine and a hot continuous rolling mill, and makes it possible to continuously roll steel billets without cutting them. This endless rolling method is characterized in that a looper device and a soaking furnace are installed between the continuous casting control device and the rolling control device, and a continuous casting control device and a rolling control device are synchronously controlled.

The method of the present invention will be explained in detail below.

The steel billet 4 cast by the continuous caster is discarded by a shearer 5 to remove the defective part at the tip, then passes through a looper 13, passes through a soaking furnace 14, and is then passed through a rough rolling mill 8, an intermediate rolling mill 10, It is continuously transferred to the finishing rolling mill 11.

The casting control device 21 of the continuous caster casts the molten steel in the mold 3 while solidifying the outer surface into a shell shape, so the casting control device 21 controls the drawing speed of the billet and the cooling rate of the billet while keeping the meniscus level constant. It has a control function.

When pouring molten steel from a ladle or tundish in a continuous casting machine, if problems such as impurity inflow or nozzle clogging occur, the drawing speed must be suddenly reduced.
The speed change is rapid.

On the other hand, in rolling, it is necessary to keep the product shape constant.
), and many rolling mills are installed. These rolling mill groups are operated at a constant speed, and especially the finish rolling mill on the exit side is operated at a high speed. Therefore, these cannot follow sudden speed changes.

A rolling control device 22 that controls the rolling mill performs rolling control, speed control, tension control, etc. to keep the shape of the rolled steel material constant.

Rolled products also need to be rolled under the most appropriate processing temperature.

As mentioned above, the content controlled by a continuous caster and a rolling mill is different, and in order to combine these two processes, it is necessary to It is necessary to perform synchronized control with the machine.

In the present invention, a looper 13 and a soaking furnace 14 are provided between a continuous casting machine and a rolling mill to control the entire caster.

The looper 13 absorbs the speed difference between the casting speed of the continuous casting machine and the rolling speed of the rolling mill, thereby smoothly performing endless rolling.

The looper 13 bends the steel billet 4 between the pinch rolls 6.6a provided at two locations downstream of the continuous casting machine, and expands and contracts the length of the steel billet between the pinch rolls 6.63. , absorbs the speed difference between the input side and the output side of the looper 13.

Pulse transmitters 25.25 are attached to the pinch rolls 6.6a on the inlet and outlet sides of the looper 13, and these pulse transmitters detect the speed at which the steel billet passes through each pinch roll portion.

The steel billet 4 can be bent once or several times in the vertical direction, in the lateral direction, or in any other direction depending on the cross-sectional dimensions of the steel billet. Or, in the case of a wide plate material, for example, by giving it a 90 degree twist and changing its direction into an L-shape, it is possible to spatially increase the amount of buffering. FIG. 3 illustrates such an example.

The method of bending the steel piece 4 is to attach an adjusting device to the pinch roller 6.6a, which consists of a roller that pushes the side surface of the steel piece 4, an actuator that applies thrust to the rollers, and a controller that operates this actuator. This method is controlled by a signal from an installed pulse generator. The amount of curvature of the looper, that is, the amount of buffering, is detected by a position detector consisting of a light-emitting end 26 and a light-receiving end 27 (5). communicated.

When the speed change of the meniscus 1 novel or the pinch roll on the side of the looper is input, the synchronization control device 23 operates the looper within the set range of the looper adjustment amount to buffer the amount of change, while controlling the pinch roll on the exit side of the looper and the rolling speed. Control the speed and tune to the corresponding speed.

In the soaking furnace J4, the steel billet 4 is soaked by recuperation from the high temperature portion inside the steel billet. A thermometer 24 provided on the outlet side of the soaking furnace 14 measures the surface temperature of the soaked steel billet, and issues a command to the continuous casting control device 21 of the continuous casting machine based on this measured value.

The continuous casting control device 21 controls the cooling amount based on this command.
, the cooling surface is controlled to achieve the most appropriate rolling temperature on the exit side of the soaking furnace.

The uniformly heated steel billet 4 is successively passed through a group of rough, intermediate and finishing mills to be rolled.

(6) There is no need to install a rod shear between the rolling mills, unlike in the past.

FIGS. 4(a) and 4(b) are examples illustrating changes in the looper inlet speed (drawing speed of continuous casting) and the louver outlet speed (roughing mill inlet speed), respectively.

After the continuous caster starts casting, the steel piece gets caught in the looper's side pinch roll (point A), and after a few minutes, it gets caught in the output side pinch roll. (Point A'). 131 points correspond to the speed change (point B) when changing the ladle after casting one hit. If an injection problem occurs in the second heat and the speed of the pinch roll on the louver man side changes suddenly as shown in C, the rolling mill cannot cope with this, but the louver absorbs this sudden change and the speed of the pinch roll on the louver exit side changes. was controlled like C'.

According to the present invention, it has become possible to directly connect the continuous casting machine and the rolling mill, resulting in the following effects.

(1) Great energy saving effect. By appropriately controlling the amount of cooling in the continuous casting machine, it became possible to uniformly heat the steel billet by recovering heat from inside the billet without heating it in a soaking furnace.

(7) (2) Yield is significantly improved. Since rolling is performed continuously in one to several heats of continuous casting, end crops are formed only at both ends of the rolling unit, and the generation of scrap is significantly reduced.

(3) Rolling operations become stable. Since endless rolling is performed, there is no contact when the rolls are connected to the rolls, so the lifespan of the rolls is extended, and intermediate crop shears and guides are not required, resulting in lower equipment costs.

(4) Labor is saved because there is no need to handle billets, etc.

[Brief explanation of drawings]

Figure 1 shows the working process of a conventional continuous casting machine and rolling mill - entry side,
It is a graph showing an example of the velocity of the steel billet on the exit side. 1... Take M, 2... Tan tissue, 3... Mold 4... Steel piece, 5... Shearing machine, 6, 6a...
Vinci roll, 7... Heating furnace, 8... Rough rolling mill, 9
... Crop shear, 10... Intermediate rolling mill, 11.
... Finish rolling (o) machine, 12... Rolled steel material, 13... Louver, 14.
... Soaking furnace, 21 ... Casting control device, 22 ... Rolling control device, 23 ... Tuning control device, 24 ... Thermometer, 25 ... Pulse transmitter, 26.27 ... - Louver buffer amount detection device. (9) 1 6'

Claims (1)

[Claims] 1 The continuous casting machine and hot continuous rolling mill are connected via a louver device and a soaking furnace, and the cooling amount of the continuous casting machine is controlled by the temperature at the outlet of the soaking furnace, and the casting speed and rolling are controlled by the buffering of the looper device. An endless rolling method that absorbs speed differences and continuously rolls continuously cast steel billets.