RU2146974C1 - Method for making endless hot rolled strip in continuous-reversing casting-rolling aggregate - Google Patents

Abstract

FIELD: rolled stock production, possibly making hot rolled strips and sheets in metallurgical plants. SUBSTANCE: method comprises steps of passing slab along through type furnace after it leaves continuous casting plant; in furnace coiling slab to intermediate coil on drum by double-start coiling; moving apparatus for forming coil towards rolling mill; at accumulating necessary for first pass quantity of coiled strip reversing drum and beginning first pass in rolling mill; placing apparatus for forming coil in the same direction; at uncoiling intermediate coil simultaneously due to difference of metal speed in outlet of apparatus for forming coil and metal speed in inlet of rolling mill accumulating slab excess in apparatus for looping; delivering accumulated slab excess to rolling zone after terminating intermediate coil uncoiling; then reversing rolling mill and beginning second pass of first portion; at process of second pass of first portion coiling strip onto drum after it leaves billet continuous casting plant and rolling mill; moving apparatus for forming coil towards billet continuous casting plant to initial position; after second pass reversing rolling mill and beginning third pass while starting strip uncoiling from drum; moving coiler to rolling mill; coiling rolled strip on coiler. After end of third pass of first portion of slab there is intermediate coil accumulated onto drum in quantity necessary for rolling second portion of slab. Second portion of slab and all subsequent portions are rolled in the same way as first portion. EFFECT: increased speed of slab guiding to rolls of rolling mill during first pass and therefore stable temperature mode of rolling. 11 dwg

Description

 The invention relates to the field of rolling production and can be used in the shops of hot sheet rolling of metallurgical plants.

 A known method for the production of hot rolled strips, including continuous casting of a thin slab on a continuous casting machine, cutting it into sections of a certain length, heating the cut sections of the slab in a continuous heating furnace, rolling them into strips on a multi-strand continuous mill, cooling the strips in a cooling device, and winding them onto final winder (see application EP N 0266564, CL B 21 B 1/46, publ. 1988).

 A disadvantage of the known method is the relatively low rolling speed in a continuous multi-bench mill in the absence of special technical means for controlling the rolling temperature, which limits the ability to maintain the strip temperature in a narrow range.

 The closest analogue to the claimed object is a method for the production of hot rolled strips on a continuously reversible casting and rolling unit, including continuous casting of metal into a thin slab, its heating and accumulation by two-input winding into an intermediate roll with simultaneous movement of the roll, periodic issuance of successive sections from the accumulation zone in the process of unwinding an intermediate roll, rolling into an endless strip with these individual sections in several passes with the return of the rolled ASTK band in the accumulation zone, cooling of the strip, and cutting of the winding in the finished rolls (see. International Application WO N 92/18262, cl. B 21 B 1/46, publ. 1992).

 However, the implementation in the known method of the operation of accumulating a continuously cast slab and a rolled section into one intermediate roll leads to the fact that when rolling each section of the slab in the first pass, a certain part of it is forced to set in the rolling mill at a very low speed equal to the speed of continuous casting. As a result, the cooling time of this part of the rolled section of the slab is much longer than the cooling time of the remaining parts, which, in turn, causes significant temperature losses of the metal and, accordingly, leads to an increase in the energy-power parameters of rolling and an increase in the energy consumption for it. The resulting temperature non-uniformity along the length of the rolled section leads to heterogeneity of the metal structure and uneven mechanical properties along the length of this section.

 The basis of the invention is the task of creating such a method for producing an endless hot rolled strip on a continuously reversible unit, which will stabilize the temperature regime of rolling by reducing the cooling time of part of the rolled section of the slab by supplying it in the first pass to the rolling zone at a speed higher than the casting speed, which will lead to improved quality of the finished product by increasing the uniformity of the mechanical properties of the metal along the length of this section of the strip.

 The problem is solved in that in the known method for producing an endless hot rolled strip on a continuously reversible casting and rolling unit, including continuous casting of metal into a thin slab, its heating and accumulation by two-input winding into an intermediate roll with simultaneous movement of the roll, periodic issuance from the accumulation zone successive sections in the process of unwinding the intermediate roll and subsequent rolling into an endless strip of these individual sections for several passes with return by rolling the rolled section of the strip into the accumulation zone, cooling the strip, cutting and winding it into finished rolls, according to the invention, in the first pass of each section of the slab simultaneously with the unwinding of the intermediate roll, part of the rolled section is accumulated by looping, and the accumulated loop-like excess of the slab is released into the rolling zone after the end of the unwinding of the intermediate roll.

It is known in the method for the production of hot rolled strips and sheets that accumulation by loop formation on an intermediate live table of a broadband hot rolling mill (see ed. St. USSR N 1680390, MKI ⁵ B 21 B 1/26). The specified technique in the known method is designed to accommodate a long roll on a short intermediate roller table.

 In the inventive method, the loop formation of part of the rolled portion of the thin slab is carried out in a continuous furnace in the first pass simultaneously with the unwinding of the intermediate roll and rolling. These distinctive features characterizing the new sequence of operations allow the manifestation of a new technical effect, which is to stabilize the temperature of the rolling, which is achieved by reducing the cooling time of the part of the rolled slab, issued in the rolling zone after the unwinding of the intermediate roll in the first pass at high speed, namely, at the speed of entering the strip in the mill in the first pass. This speed is achieved by issuing into the rolling zone the excess slab accumulated in the loop. As a result, all cross sections of the rolled section of the strip are cooled for the same time and a temperature gradient along the length of the strip is not formed.

 Based on the above analysis of known sources of information, we can conclude that for a specialist the inventive method for producing an endless hot rolled strip on a continuously reversible casting and rolling unit does not follow explicitly from the prior art, and therefore meets the condition of "inventive step".

The invention is illustrated by drawings, where
in FIG. 1 shows a General view of a continuously reversible unit for implementing the proposed method;
in FIG. 2 - stage of the task of a thin slab in the passage of the unit;
in FIG. 3 - the beginning of the operation of forming the intermediate roll;
in FIG. 4 - the end of the operation of forming the intermediate roll;
in FIG. 5 - the first pass of the first section of the slab, in which simultaneously with the unwinding of the intermediate roll, the accumulation of excess slab begins;
in FIG. 6 - the moment of the end of the unwinding of the intermediate roll in the first pass and the completion of the operation of accumulating excess slab by looping;
in FIG. 7 - the operation of issuing a loop-like excess slab in the rolling mill;
in FIG. 8 - the second passage of the first section of the strip;
in FIG. 9 - the third passage of the first section of the strip;
in FIG. 10 - the first pass of the second section of the slab, in which simultaneously with the unwinding of the intermediate roll begin the accumulation of excess slab;
in FIG. 11 - the moment of completion of the unwinding of the roll in the first pass of the second section of the slab and the completion of the operation of accumulating excess slab in the loop.

 The casting and rolling unit for implementing the method of continuous production of an endless hot-rolled strip includes sequentially installed in line a continuous casting machine of preforms 1 (Fig. 1) of any known design, a passage device 2 (Fig. 1 - 11) for heating, accumulation of a slab and a rolled section of the strip of known design, a device 3 for looping a slab installed in the rear of the passage 2, a reversible rolling mill 4 for rolling the slab into a strip in separate sections for several There are a few passes, a device 5 for cooling a strip, a device 6 for cutting an endless strip, and end winders 7 for winding hot-rolled strips into finished rolls. The passage device 2 for heating, accumulating the slab and the rolled section of the strip comprises a roller furnace 8 and a device 9 for forming and moving an intermediate roll. The device 9 comprises a trolley 10 located on the outside of the roller furnace 8, and a drum 11 and two pairs of pulling rollers installed inside the trolley 10. The device 3 for looping a slab contains two pairs of pulling rollers 13 (only the lower rollers are shown in Figs. 1-11) 13) and loop forming roller 14.

 The inventive method of producing an endless hot rolled strip is described for the case of reverse rolling of each section of the slab in three passes and is carried out as follows.

After casting in a continuous casting machine 1 (Fig. 1), a thin slab enters the roller furnace 8 (Fig. 2) of the feed-through device 2 with a casting speed (ν _l ). At the same speed, its front end moves in the furnace 8 through the gaps of the pulling rollers 12 and the slot of the drum 11 of the device 9 for forming and moving the intermediate roll to the rolling mill 4. The device 9 (Fig. 2, 3) moves from position I (Fig. . 2) to position II (Fig. 3). At the moment of approaching the front end of the slab to the entrance to the mill 4 (Fig. 3), the device 9 approaches the position II (Fig. 3) of the beginning of the winding of the slab in the intermediate roll. From this moment, the winding of the slab into the intermediate roll on the drum 11 (Fig. 4) of the device 9 begins with the simultaneous movement of the wound roll in the direction of the metal flow. At the end of the winding device 9 (. Figure 4) suitable to position III, where the intermediate roll begin unwinding at a speed ν _p1 = (ν _l -ν _n1) / 2 wherein ν _p1 - the speed of unwinding of the roll in the first pass; ν _p1 - the speed of the slab in the area between the device 9 and device 3; ν _l is the casting speed, with the simultaneous movement of the device 9 in the direction of the metal flow at a speed of ν _m1 = (ν _p1 + ν _l ) / 2, where ν _m1 is the speed of movement of the device 9. At the same time, the first pass of the first section of the slab in the rolling mill begins 4 (Fig. 5) with a speed of ν _p1 - with compression from a thickness h ₀ to a thickness h ₁ . The velocity of the output device 9 of the slab, equal to _n1 ν = (ν _m1 + ν _p1), greater than the velocity ν _p rolling the slab in the first portion 4. This enables the mill simultaneously with the unwinding of the intermediate roll by the difference in velocity ν and ν _{n n1} accumulate part of the rolled portion of the slab by looping in the device 3 (Fig. 5, 6). At the time of the approach of the device 9 (in Fig. 6) to position IV, the unwinding of the intermediate roll is completed, and the device 9 begins to move in the opposite direction. At the end of the unwinding of the intermediate roll in the device 3 (Fig. 6) accumulated in the loop maximum excess slab. After the unwinding is complete, sampling of the loop-like excess of slab accumulated in the device 3 (Fig. 7) into the rolling zone is started. In this case, the slab still leaves the device 3 into the rolling zone at an increased speed ν _p , which ensures the same cooling time for all cross sections of the strip, as a result of which a temperature gradient is not formed along the length of the strip, i.e., the rolling temperature is stabilized. At the end of the first pass of the first section of the slab, the device 9 (Fig. 8) approaches position II, and from the device 3 the accumulated loop-like excess of the slab is completely selected. After that, the rolling mill 4 (Fig. 8) is reversed, the roll gap is reduced, and the second passage of the first section of the strip begins with compression from thickness h ₁ to h ₂ . At the same time, the device 9 begins to wind the intermediate roll and move it in the direction opposite to the direction of the metal flow. At the end of the second pass, the winding is stopped and the device 9 stops at position I (Fig. 9). Rolling mill 4 (Fig. 9) is reversed, the roll gap is reduced, and the third pass begins with compression from thickness h ₂ to h ₃ . At the same time, the device 9 begins to unwind and move the intermediate roll in the direction of the process metal stream. In the process of the last third pass, the strip leaving the mill 4 is cooled and wound onto the final winder 7. At the end of the last third pass of the first section of the slab, the device 9 (Fig. 10) approaches position III of the beginning of the unwinding of the slab. At the same time, an intermediate roll is necessary on the drum 11 of the device 9 (Fig. 10), which is necessary for the first passage of the second slab section. Moreover, the first passage of the second section of the slab (Fig. 10, 11) and the remaining passes are carried out similarly to the above-described passages of the first section of the slab.

 Thus, the implementation of the proposed method provides an increase in the speed of the task of the slab in the first pass into the rolling mill, which reduces the cooling time of the metal, and therefore, the inventive method allows to stabilize the temperature regime of rolling. This allows you to obtain uniform mechanical properties of the metal along the length of the strip and thereby improve the quality of the finished product.

 Based on the foregoing, we can conclude that the inventive method of producing an endless hot rolled strip on a continuously reversible casting and rolling unit is operational and eliminates the disadvantages of the prototype, which is confirmed by an example of a specific implementation. The inventive solution can be applied in the shops of hot sheet rolling of metallurgical plants, therefore, meets the condition of "industrial applicability".

Claims (1)

 A method for producing an endless hot rolled strip on a continuously reversible casting and rolling unit, comprising continuously casting metal into a thin slab, heating it and accumulating by two-way winding into an intermediate roll while moving the roll, periodically issuing successive sections from the accumulation zone in the process of unwinding the intermediate roll and subsequent rolling into an endless strip by these separate sections in several passes with the return of the rolled section of the strip to the accumulation zone , cooling the strip, cutting and winding it into finished rolls, characterized in that in the first pass of each section of the slab simultaneously with the unwinding of the intermediate roll, part of the rolled section is accumulated by looping, and the accumulated loop-like excess of the slab is fed into the rolling zone after the unwinding of the intermediate roll.

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