UA72015C2 - Method and device for hot rolling of a thin strip - Google Patents

Abstract

The invention relates to the method of hot rolling of thin strip on the mills containing roughing reverse stand and finishing rolling group with furnace coilers. A method for hot rolling of thin strip consists in reverse roughing rolling of the slab in the roughing stand up to the intermediate thickness, transfer of the strip of intermediate thickness into the finishing group consisting of one or more rolling stands, reverse finishing rolling of the strip in the finishing rolling group up to the final thickness with winding û unwinding of the strip of intermediate thickness on the coilers in the furnaces mounted upstream and downstream the finishing rolling group. Besides, the reverse rolling of slab in the roughing stand is performed in parallel with the reverse rolling in the finishing rolling group obtained from the previous slab, and the strip in at least one unpaired roughing cut, except for the last unpaired pass, are passed without turning through the rolling device, during the last roughing pass the strip is rolled up in the intermediate roll in the rolling device followed by the unrolling for transfer of the strip into the finishing rolling group, in this case the completion of the cycle of the finishing rolling of the previous strip is performed simultaneously with the transfer of the next strip into the finishing rolling group. The mill for production of thin hot-rolled strip includes heating furnace, transport and working rollers, roughing reverse stand, finishing rolling group consisting of one or more rolling stands, coilers in the furnaces mounted upstream and downstream the finishing rolling group, shears with draw rolls, coiler for winding of finished strip into the roll. The mill is equipped with rolling device, the distance with this device and roughing stand is selected in such a manner that it shall not exceed the length of semi-finished rolled product in the next to last unpaired roughing pass and is regulated by the mathematical dependence. The invention ensures favorable temperature parameters and reduces the length of the processing line of the mill.

Description

Description of the invention

The invention relates to methods of hot rolling of thin stock on mills containing a rough reversible 2 rolling cage and a finishing rolling group with furnace winders.

A known method of production of hot-rolled staffs on a semi-continuous condition (US patent Mo3803891, IPC

B2181/32). The state that implements this method contains: - a furnace for heating slabs; - transport and working roller gangways; - Draft reversible rolling cage; - folding machine; - flying scissors; - net rolling group consisting of six non-stop rolling cages; - winders for winding hot staff. 12 The considered method of hot rolling of the staff consists of a number of technological operations.

Slabs, after heating in the furnace and removal of scale, are sent to the draft reversible rolling mill.

The stock in this cage is rolled to an intermediate thickness in several reversing passes and on the last pass is rolled into an intermediate roll in a rolling machine. The rolling operation makes it possible to reduce the rolling fields between the draft cage and the finishing rolling group, to improve the temperature conditions of the rolling stock in the finishing rolling group due to the preservation of the heat of the stock in the roll.

The rolling of the staff in the finishing group of cages is carried out continuously with its unwinding from the intermediate roll and ends with winding on one of the winders of the hot staff.

The disadvantage of the described method of production and the rolling mill is the need to place between the draft cage and the rolling machine a roll of intermediate length (after the penultimate odd pass of the draft), which can be several tens of meters (40-50) and leads to the loss of heat by the staff in the last draft (3 pass and further during transportation to the rolling machine during the last draft pass, which leads to a decrease in the quality of the resulting stock. In addition, the mill that implements this method of rolling has large dimensions, its manufacture is associated with significant capital costs.

As a prototype, the method of rolling a thin staff on the condition described in the US patent Mo4497191, IPC about

B21841/02 dated February 15, 1985. "-

The state that implements this method contains the following equipment: - a furnace for heating slabs; o - transport and working roller gangways; Ha - universal reversible draft cage;

Zo - a reversible two-cell finishing rolling group, before and after which the winders in the furnaces are installed; - - flying scissors; - a winder for winding the finished staff.

In this method, in order to preserve the temperature parameters of rolling, the reversible draft cage is as close as possible to the finishing rolling group with the condition of placing the furnace winder between them. With 70 In this connection, rough rolling is carried out under the conditions of transportation of the undercut through the open rolls of finishing cages.

From" During the last rough pass, rolling takes place simultaneously in the rough cage and the finishing cages, after which the staff is wound on a winder in the furnace.

Finish rolling is carried out by the staffs in a two-cell continuous reversing group with winding - unwinding of the staffs on winders in furnaces installed in front and behind the group of cages. and Trimming of the ends of the staff during finishing passes is carried out with flying scissors. ka Such a state is compact, has much smaller dimensions and requires lower capital costs during construction.

However, this method has significant disadvantages: o - reduced state productivity due to the placement of the pad during draft passes in the area of the finishing cages and - 20 their forced downtime during the period of draft passes, which increases the production cycle time; - deterioration of the operational reliability of the condition due to transportation during rolling of slabs and rolled slabs of large thickness to the area of finishing cages; - the deterioration of the quality of the staffs due to the appearance of a large temperature "wedge" along the length of the staffs, which occurs in connection with the reduced rolling speed in the common rough and finishing passes, because after the finishing 29th pass the staffs must be fed into the furnace winding machine at a speed of no more than 2 ,5 m/s.

GF) The basis of the invention is the task of creating a method of rolling stock, which ensures high productivity while simultaneously improving the quality of stock. o This task is solved due to the technical result, which consists in combining the time of rolling in the rough cage and rolling in the finishing rolling group, as well as reducing the temperature "wedge" along the length of 60 staffs, thanks to its folding into an intermediate roll after the last rough pass.

To achieve the above-mentioned result in the method of hot rolling of thin bars, which includes reversible rough rolling of the slab in the rough cage to an intermediate thickness, transfer of the bars of intermediate thickness to the finishing rolling group consisting of one or more rolling cages, reversible finishing rolling of the bars in the finishing rolling group to the final thickness with winding - unwinding of intermediate thickness staffs on the winding machines in the furnaces, installed before and after the finishing rolling group, according to the invention, the reverse rolling of the slab in the rough cage is carried out in parallel with the reversing rolling in the finishing rolling group of the staffs obtained from the previous slab, and the staff in at least one odd rough pass, except for the last odd pass, is passed without winding through the provided wrapping device, after the last rough pass of the staff is rolled into an intermediate roll in the wrapping device, with subsequent unfolding for the task of the staffs in a clean rolling group, while this is finished of the final rolling cycle of the previous headquarters is carried out simultaneously with the task of the next headquarters in the final rolling group.

In addition, in order to achieve the above technical result, a mill for the production of thin hot-rolled stock, including a heating furnace, transport and working roller gangways, a rough reversible cage, a finishing 7/0 rolling group consisting of one or more rolling cages, winders in furnaces, installed in front of and behind the finishing rolling group, shears with traction rollers, a winder for winding the finished stock into a roll, according to the invention, equipped with a winding machine, the distance between which and the draft cage is chosen on the condition that it is no more than the length of the roll in the penultimate odd draft pass, and the distance between the rough cage and the first cage of the finishing rolling group is chosen on the condition that it is determined by the length /5 staffs in the penultimate odd rough rolling pass according to the formula: 2

Ge in tab, glue

D - the distance between the rough cage and the first cage of the finishing rolling group;

Its headquarters. - the length of the staff in the penultimate odd rough rolling pass;

Mp - the speed of the staff during rolling; a - deceleration when braking staffs; d. - the distance from the first cage of the finishing rolling group to the shears with pulling rollers.

As a result of a comparative analysis of the proposed method of hot rolling of thin bars with the prototype, it was established that they have the following general features: c - reversible rough rolling of slabs in a rough cage to an intermediate thickness; o - reversible finish rolling in the finish rolling group to the final thickness; - winding - unwinding of intermediate-thickness staffs during finishing rolling on winders in furnaces installed before and after the finishing rolling group; and distinguishing features: Io) - the reverse rolling of the slab in the rough cage is carried out in parallel with the reverse rolling in the finishing "- rolling group of staffs obtained from the previous slab; - staff in at least one odd draft pass, except for the last odd pass, is passed without. (3 folds through the provided folding device; sch - after the last rough pass of the staff, they are rolled into an intermediate roll in the folding device, with subsequent unfolding for the task of the staffs in the finishing rolling group; - - the end of the cycle of finishing rolling of the previous staffs is carried out simultaneously with the task of the next staffs in the finishing rental group.

Thus, the proposed method of hot rolling of thin stock has a new sequence of operations and a new method of operations.

As a result of the comparative analysis of the proposed state for the production of thin hot-rolled bars with - with the prototype, it was established that they have the following general features: и - heating furnace; -» - transport and working roller gangways; - Draft reversible cage; - net rental group; - and - winders in furnaces, installed before and after the finishing rolling group; 7 - scissors with pulling rollers; - winder for winding the finished staff into a roll; and distinguishing features: («c) - the offered condition is supplied by a rolling machine; -l 20 - the distance between the folding machine and the draft cage is chosen on the condition that it is not greater than the length of the roll-up in the penultimate odd draft pass; sl - the distance between the rough cage and the first cage of the finishing rolling group is chosen on the condition that it is determined by the length of the staff in the penultimate odd rough rolling pass by the formula: 2

Ge v tab, glue (FI G - the distance between the rough cage and the first cage of the finishing rolling group;

It tab. - the length of the staff in the penultimate odd rough rolling pass; o Mp - the speed of the staff during rolling; a - deceleration when braking staffs; bo d. - the distance from the first cage of the finishing rolling group to the shears with pulling rollers.

Thus, the proposed state for obtaining thin hot-rolled staff has new connections between machines.

There is a cause-and-effect relationship between distinctive features and the technical result achieved.

Thanks to the parallel rolling of the slab in the rough cage with rolling in the final rolling group of the slab obtained from the previous slab, it became possible to shorten the cycle of the slab rolling (Fig. 3, 4), which led to an increase in the productivity of the mill.

Due to the fact that the staff in at least one odd draft pass, except for the last odd pass, is passed without winding through the provided wrapping device, it became possible to shorten the distance from the draft cage to the winding machine, and, accordingly, to reduce the time of transportation of the staffs in the last pass from the draft cages to the folding machine, that is, to reduce the cooling and temperature "wedge" along the length of the staff and improve its quality.

Thanks to the fact that slabs and rolls of great thickness are not transported during rolling into the equipment area of the finishing cages, the operational characteristics of the state are increased.

Due to the fact that, after the last rough pass, the staff is rolled into an intermediate roll in a 7/o wrapping device, followed by unfolding for placing the staffs in the final rolling group, it became possible to reduce the time of rough rolling, because the folding of the staffs takes place without reducing the speed of rough rolling. and, therefore, reduce temperature losses, as well as reduce the temperature "wedge" along the length of the staff when it is folded into an intermediate roll and thus improve the quality of the staff.

Due to the fact that the end of the finishing rolling cycle of the previous staffs is carried out simultaneously with task /5 of the next staffs in the finishing rolling group, temperature losses of the staffs are reduced and its quality is improved in the process of the next finishing rolling.

Thus, the use of the proposed method and condition for the production of thin hot-rolled bars provides an increase in the productivity of the process while simultaneously improving the quality of the bars.

Excluding at least one of them from the above set of distinguishing features does not provide a solution to the 2nd task - obtaining a highly productive method of rolling thin stock on a mill while simultaneously improving the quality of the stock.

The claimed technical solution is not known from the prior art, therefore it is new.

The proposed technical solution has an inventive level, because the method and condition for obtaining a thin hot-rolled staff, considered above, for a specialist in the existing way does not follow from the state of the art. high school

The claimed technical solution is industrially applied, because its technical and technological implementation does not present any difficulties. According to this decision, a sketch design of the condition for the production of thin i) hot-rolled steel at the Novolipetsk Metallurgical Combine was completed.

Thus, the proposed technical solution can be granted legal protection, because it is new, has an inventive level and is industrially applied, that is, it meets all the criteria of an invention. The invention is explained by the drawings, which show: in Fig. 1 - a state line for the production of a thin hot-rolled staff with one finishing cage; -- in Fig. 2 - the state line for the production of thin hot-rolled bars with two finishing cages; o in Fig. 3 - a cyclogram of the state of operation according to the proposed method of hot rolling of a thin stock; in Fig. 4 is a cyclogram of the state of work according to the well-known method of hot rolling of a thin stock (US patent c. 5 Mo4497191); Fig. 5 - graphs of temperature changes along the length of the staff before entering the clean rolling group (a) and leaving it (b) in the known and proposed methods of hot rolling.

The mill for hot rolling of thin stock 1 (Figs. 1, 2) consists of a heating furnace, a device for hydraulic slag crushing (not shown in Figs. 1, 2), transport and working roller conveyors 2, a draft reversible cage "

C, finishing rolling group consisting of one 4 (Fig. 1) or more rolling cages 4 (two cages 4, 4a with c in Fig. 2); coiling machine (coil box) 5; rollers b in the furnace 7, installed in front of the finishing rolling group; winders 8 in the furnace 9 installed after the finishing rolling group; scissors with transport rollers;" 10, 11 for trimming staffs; winder for winding the finished staff into a roll (not shown in Fig. 1, 2).

The distance between the draft reversing cage C and the folding machine 5 and is chosen on the condition that it is not greater than the length of the pick-up in the penultimate odd-numbered draft pass. - And the distance Y between the rough reversing cage Z and the finishing reversing cage 4 is determined taking into account the placement between them of the staffs in the penultimate odd rough rolling pass, as well as the location relative to the finishing reversing cage 4 of shears with pulling rollers, 10 and the section o of the roller conveyor on which the staff slows down from rolling speed to a full stop before reversing. In an analytical form, this distance can be written: 2 "p inv kak de Tsutab. - The length of the staff in the penultimate odd rough rolling pass;

Mp - the speed of the staff during rolling; a - deceleration when braking staffs; o d. - the distance from the first cage of the finishing rolling group to the shears with pulling rollers.

The proposed method of hot rolling of thin stock is carried out by performing the following technological operations.

The slab heated in the furnace is fed into the draft cage Z (see Fig. 1, 2), where in the mode of reverse rolling in 5 60 passes (see Fig. 3) (I, Ш, Ш, IM, М) it is rolled into the intermediate of the headquarters (undercut) with a thickness of З5Bmm.

Energy parameters of rough rolling are given in Table 1. Since the rolling machine in the proposed state is installed from the rough cage C at a distance not greater than the length of the roll in the penultimate odd pass (PI) ("2bm), the roll in this pass is passed through the rolling machine without folding, for which its transport elements are installed at the rolling level (see Fig. 1). Because the distance between the rough 65 cage C and the finishing cage 4 (I) is chosen according to the above formula (in this particular case -Zbm), the feed after the 3rd pass is located between the rough cage C and the shears with pulling rollers 10.

During the last draft pass (M), the pad is folded in the folding machine 5, installed in the working position (as shown in Fig. 2). Roll-up is carried out at the speed of rough rolling (Zm/s).

This operation allows you to complete the rough rolling autonomously without activating the finishing group and without reducing the rough rolling speed to 0.375-0.54 m/s, despite the fact that the length of the roll in the M pass is greater than the distance between the rough cage C and the finishing cage 4. In addition, the operation of collapsing the staff into an intermediate roll allows you to maintain its temperature and reduce the temperature "wedge" along its length before being transferred to the final rolling group (see graphs in Fig. 5).

After the end of rough rolling and rolling of the roll into an intermediate roll, it is unfolded and 7/o feeding of the roll into the finishing group for reversible finishing rolling.

Finishing rolling occurs as follows (considered version with two cages 4, 4a (Fig. 2).

Before the task of staffs 1, in the finishing cage 4, 4a, the section of the front end of the tackle is cut using scissors with pulling rollers 10.

After the first (I) finishing pass (passage through cages 4, 4a), the staff with a thickness of 7.5...10.00 mm is wound on a /5 mm winder (see Fig. 3).

Filling of the staffs in the winder 8 takes place at a speed of about 2m/s, which determines the speed of entry of the feed into the first cage (0.375...0.54.m/s).

After "grabbing" of the staffs by the winder 8, the cages 4, 4a and the winder 8 accelerate to the rolling speed, at this speed the rolling of the main part of the staffs (pass I) takes place, after which the finishing cages 4, 4a and the winder 8 slow down to a speed of approximately 2m/s. at this speed the rear end of the staff rolls.

Rolled in finishing cages 4, 4a of the staff stops in front of the winder 8 in the area of action of scissors with pulling rollers 11. The rear end of the staff is cut off.

Next, the staffs are reversed and the second pass (II) through cages 4, 4a. At the same time, along with the unwinding of the staffs from the winder 8, it is wound on the winder 6. The filling of the staffs in the winder 6 and the end of the rolling process of the staffs in the second pass are carried out at a speed of approximately 2 m/s. Rolling of the main part of the staff takes place at the required rolling speed. and)

Rolled in finishing cages 4a and 4 of the staff, it stops in front of the winder 6 in the area of action of scissors with pulling rollers 10. The rear end of the staff is cut off.

After that, the staff is reversed and its final rolling to the required thickness at the required technical level

From Speed (pass 1PI).

The power parameters of finishing rolling can be found in Table 1. --

A characteristic feature of the proposed method of hot rolling of thin stock and the condition for its implementation is that the reverse rolling of the next slab in the draft cage begins to be carried out in parallel with the clean rolling of the previous slab (rolling), with the coordination of the rolling cycles, as shown in the cyclogram of Fig. 3. In this case, the time of parallel c c5 rolling is approximately 80 seconds and is highlighted by the shaded area. The end of the rough rolling cycle (passage M), its collapsing with the subsequent unfolding for the task in the finishing cages and the end of the finishing rolling cycle are carried out simultaneously. Therefore, the pause time A in the finishing rolling group is no more than 5 seconds.

We compare the rolling technology of the proposed method with the rolling technology of the prototype method. "

The cycle diagram of the condition of the prototype is shown in Fig. 4 (the rolling staff with the same parameters as in the proposed condition is considered). . In the prototype, the rough cage is as close as possible to the final rolling group, and the minimum of this is the distance is limited by the need to place between the draft cage and the first cage of the finishing rolling group of the winder in the furnace.

This mutual location of the cages leads to the fact that in the intermediate odd passes, the tackle enters the -I zone of the finishing cages, the rolls of which must be kept open at this time. This excludes parallel rough and finish rolling of adjacent rolls, which determines the pause time in the finishing group (marked A/ in Fig. 4), which in the considered case is 85 seconds. o The time of the rolling cycle consists of the time of finishing rolling and the time of pause in the finishing cages and for prototype 5o is 510-85-595s. - In the proposed method, due to the optimal mutual location of the rough and finishing cages, the time from the pause in the finishing group is reduced to 5 seconds, and the time of the rolling cycle according to the proposed method is 510-5-515s.

In addition, the folding of the pad after the last rough pass into the intermediate roll allows you to keep it at the same temperature and reduce the temperature "wedge" along the length of the staff at the entrance to the first finishing cage by 15470-2870-129"C (see Table 2 and the graphs in Fig. 5). advantages: - the possibility of parallel finishing rolling and rough rolling is provided, as a result of which the production cycle of the staff is determined only by the time of finishing rolling and pauses; - a small distance between the rough and finishing cages and the installation of a rolling machine ensures favorable temperature parameters of rolling | reduces the length of the technological line of the condition; 65 - slabs and rolls of great thickness are not included in the equipment area of the finishing cages hey, which increases the operational characteristics of the condition;

- the adopted state scheme allows to transform it into a semi-continuous one when used in a clean rolling group from 5 to 7 cages;

Slab parameters: 250x1350x10500mm. Weight 27.8 tons.

Material: low carbon steel.

Staff parameters: 1.50x1350 mm.

Table 1

Number | INumber Thickness of staffs, mm Relative Length | Speed Effort Moment Temper tour staffs / cages |pass at the entrance to compression, 95 staffs, m/| rolling, m/s of rolling, ts of rolling, tsm at the exit from the cage, "C in the cage at the exit from the cage in mo /17me | 6 17777vyu 1. Temperature of heating the slab: 12007 s 29 2. Temperature of the space in the Steckel furnace: 100070. g ) 3. The temperature of the surface of the drum in the Steckel state furnace: 90070. 4. The distance between the rough and the first finishing cages - Zbm. 5. The beginning of winding in the furnaces - after | the finishing pass. 6. The rolling speeds in the finishing passes are given taking into account the rolling speeds of the front and about the rear ends of the roll, which differ from the rolling speeds of the main part of the staff. "- 7. Efforts and moments of rolling, as well as the temperature of the staff are given for the main part of the staff. 8. Rolling cycle - 510s. Hourly productivity of the mill - 196t. o s

Table 2

Speed Length of staffs, 95 starting from Temperature of staffs, "C and - rolling, m/s|front end Exit from the draft cage (last Entry to the first finishing Exit from the second finishing rough pass) cage cage (ready headquarters) prototype proposed method | prototype / proposal |prototype |proposal method « method 1066 BUT 1087

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Claims (1)

The formula of the invention and - 1. The method of hot rolling of thin stock, which includes reversible rough rolling of the slab in a rough cage to an intermediate thickness, transfer of intermediate thickness to a finishing rolling group consisting of one or more rolling cages, reversible finishing rolling of the slab in a finishing rolling group to the final thickness with " 70 Winding - unwinding of intermediate-thickness staffs on winders in furnaces, installed before and behind the final rolling group, which is distinguished by the fact that the reverse rolling of the slab in the rough cage is carried out in parallel with the reversible rolling in the final rolling group of staffs obtained from of the previous slab, and . and the staff in at least one odd rough pass, except for the last odd pass, are passed without folding through the provided rolling device, during the last rough pass of the staff, they are rolled into an intermediate roll in the rolling device, with subsequent unfolding for the purpose of setting the staffs into a clean rolling group, -I at the same time, the end of the finishing rolling cycle of the previous headquarters is carried out simultaneously with the task of the next headquarters in the finishing rolling group. ko 2. A condition for the production of thin hot-rolled stock, which includes a heating furnace, transport and working roller gangways, a draft reversible cage, a finishing rolling group consisting of one or more rolling cages, winders in furnaces installed before and after the finishing rolling group, scissors with pulling rollers, - a winder for winding the finished staff into a roll, which differs in that it is equipped with a winding machine, the distance between which and the draft cage is selected on the condition that it is not greater than the length of the roll in the penultimate odd draft pass, and the distance between the rough cage and the first cage of the finishing rolling group is chosen on the condition that it is determined by the length of the staff in the penultimate odd-numbered rough rolling pass according to the formula: I. - AH5 to headquarters. and 1 in 60 G - the distance between the rough cage and the first cage of the finishing rolling group; It tab. - the length of the staff in the penultimate odd rough rolling pass; Mp - the speed of the staff during rolling; a - deceleration when braking staffs; g is the distance from the first cage of the finishing rolling group to the shears with pulling rollers. b5 Official bulletin "Industrial Property". Book 1 "Inventions, useful models, topographies of integrated microcircuits", 2005, M 1, 15.01.2005. State Department of Intellectual Property of the Ministry of Education and Science of Ukraine. with IS) "- "c) s and - s ;" -I name) («c) - 50 sl F) name) 60 b5