FI92161C - Method and apparatus for continuous production of a steel strip or steel sheet - Google Patents

Description

92161

Method and apparatus for continuous preparation of a steel strip or steel plate

The invention relates to a method for the continuous production of a steel strip or steel sheet from thin products produced according to the continuous arc casting method having a horizontal outlet direction.

In the steel industry, either because of the general trend or in order to overcome the crises faced in the last 10 years, especially by manufacturers using obsolete equipment, there is no need to reduce operating and investment costs and at the same time improve product quality and increase flexibility in the number of units produced. for "koil" or terMsplates. The modernization of existing te-15 steel mills or the design and implementation of new steel mills using new technological processes and equipment aims to increase productivity and economy, while improving product quality and achieving greater room for maneuver in 20 "pieces", where the end product is eliminated from the manufacturing process. .

One of the new technologies being developed to meet the current requirements for sawmilling involves the purchasing step of melting steel and rolling coils into rolls or "coils" or stacking sheets and passing the casting of thin blanks to the final thickness. in just a few of these jargon passes or molding steps, it can be further purchased as the desired end product. This has led to significant improvements in continuous casting technology, especially in the structure of the molds and the corresponding submerged casting, as well as improvements in the structure of the rolling mills and rolling mills in order to achieve the smallest possible land flow through the desired molding.

92161 2

Factories have become known - although they are called "test plants" - in which thin blanks with a thickness of about 50 mm are produced in a continuous casting process, while conventional blanks are located in the thickness range of 150 to 320 mm.

5 NSmS thin blanks will then be durable in different ways by successive rolling / filling steps; the end product is a terSna tape only a few millimeters thick. It has been suggested that the casting product - after the silk heating in the furnace - is already rolled thin, for example 10 six double-rolled rollers. Since the speed cannot be much higher than about 5 m / min, the rolling speeds on the last rolling mill of the rolling mill are too low to at least about 865 ° C to maintain the final rolling mills. In other words, the nau-15 ha cools too much between the two rolling stages with the casting speed due to the same low speed when entering the rolling mill. This solution has therefore long since been abandoned, since even with insulating devices and heated rollers, this problem cannot be solved economically; This would result in a significant increase in investment and operating costs.

The second solution is based on separating the strip before the lémpGuun, in which the lampd-processing of the strip is performed on the entire cross-sectional area of the strip. This is, for example, a tail-heated roll-bottom furnace, which, regardless of the casting speed to be taken into account, can bring the strip to a temperature of about 1100 ° C as it leaves the furnace, which is thus the optimum temperature for the rolling process. The strip is cut to a standard length, which can be, for example, 50 m for a given roll weight, while a corresponding oven length of about 150 m is required, taking into account the required buffer effect.

The thin billet or "pre-strip" can be rolled li 92161 3 thin at higher speeds from the actual casting-35 operation, and thus it is not necessary to lower the temperature below the minimum allowable temperatures in the final rolling step. Due to the over-length of the furnace - which is about three times the length of the strip section 5 - in addition to the considerable increase in equipment investment costs, the TS11Oin still requires a lot of space, which many steel mills are not prepared for.

In addition, the size of the device and thus of the oven sets limits on the strip portions to be processed in succession and thus the final weight of the bundle 10, which in turn limits the margin of maneuver available for the production of rolls with the largest diameters. Thus, in an apparatus of this type, it is not possible to use even thinner blank blanks if this would otherwise be possible as a result of the technological development of the continuous casting method. If the starting thickness is 25 mm - which has already been hypothetically already implemented - instead of 50 mm, in order to achieve the final weight of the same bundle, the strip would have to be divided into lengths of about 100 m. m, which can not be realized Kay-tannically and economically.

The object of the present invention is to provide a method as described above and a corresponding device for carrying out this method, by means of which it is possible to continuously produce a steel strip from a thin product from an arc continuous casting device without the above-mentioned disadvantages.

Above all, the separation of the blank from the casting and at least the first rolling process is abandoned, whereby the casting of the casting blank into the first rolling chair takes place at the speed of the Silia at which the rolling material exits the arc holes of the continuous casting machine. The method is thus carried out in "in line" use with unlimited flexibility, making it possible to produce rolls or sheets of any weight or length 35 without having to change the dimensions of the device 1 · '4 92161, since the separation of the thinly rolled strip takes place at least during the first rolling process or all after performing the vSlittO mast before the winding or stacking device.

5 The problem is solved by a method characterized by the following steps: a) molding of the thin product after blade drying in the first molding step above 1100 ° C lamps in the evening, 10 b) inductive heating to a lamp space of approx. 1100 ° C with the best lamp leveling possible (c) molding the thin product at a price in one other molding step, the rolling speeds always corresponding to a reduction in the span of the Kuta-15.

In the interpretation of the method, it is proposed to wind the strip between the first and the subsequent forming process. The thinly rolled strip can be wound according to the desired bundle weight after molding the thin product, or after separation of the thinly rolled strip following molding of the thin product, it can be stacked in predetermined lengths into steel plate packages, possibly cooled and cooled. The thin product is first lowered into the first rolling mill at the speed at which the product leaves * 25 from the continuous arc casting machine, and it then follows successive rolling steps at speeds corresponding to the shapes in the individual sheet costs. In this way, the rolled strip is finally either wound and separated after the desired roll weight has been reached or the strip is divided into the desired lengths and stacked into sheets. An essential feature of the present invention is the inductive reheating of the thin product after removal of the glow to lampholders at about 1100 ° C, the smoothing of the lamp state being the best possible, since in this way the subcooling of the strip can be prevented in an advantageous manner.

II

92161 5

According to an alternative embodiment of the invention, several steps of inductive heating of the thin product are designed for said molding steps. This sonication prevents excessive cooling of the myds rolling material 5, so that the necessary rolling ampoules can always be made such that the lamp states do not fall below the limit value of 860 ° C in the last molding step.

According to an alternative embodiment of the invention, the following additional steps are designed: bringing the molding steps into the sheet flow of the source blank, which is generated in the casting process; separating the bay blank silently before winding the strip or before stacking the sheets; 15 separate heating settings in successive stages / zones leave the blank of the blank.

After passing the roll chairs, the bale blank can be separated by means of a Silia device, which is in any case present for the division of the rolled strips, or it can be separated myds by means of another separating device into the first molding step.

The device for carrying out the method according to the invention is characterized by the following device parts in the following order: leveling the entire cross-sectional area of the thin product, d) at least one other rolling chair and e) a separating device.

The separating device may be located behind the first forming device, and in the silence of the first forming device and the second forming device 35, a device 92161 6 may be provided for winding a thin product onto a roll to wind tax off the roll in front of which the separating device is placed. The device for winding or winding the thin product is preferably located behind the induction heating device and in front of the second molding device.

According to the invention, either a separating device for the rolling strip and one spool for winding the strip or alternatively a separating device for the rolling strip, a cooling-10 device, a straightening device and a stacking device for the separated plates are arranged behind this device.

In an alternative embodiment of the invention, the device provides at least one induction heating device for selective heating in the footsteps of other roller chairs. Each of the female devices is preferably provided with controllable heating steps.

According to one interpretation of the invention, the device is provided with means for obtaining a blade cross-section of the rolls of the first molding device rollers and other rollers 20 to allow the blank of the blank to pass and to return the cross-sections to the shoulder. The device is equipped with myOs devices for sequentially controlling the individual heating steps of the furnaces silently against the passage of the blank, the separating device for separating the blank being the same as that used for separating the myOs roll strip, namely the separating device at the end of the device.

According to an alternative embodiment of the invention, a separation device located behind the first molding step is used to separate the blank.

To consider the invention, an exemplary embodiment described in the drawings will be described below. They show: 92161 7 a schematic partial representation of a device according to the invention and Fig. 2 a diagram 5 showing the flow of a steel strip. Fig. 3 a modified embodiment of the invention.

The drawing schematically shows an apparatus according to the invention, on the basis of which a corresponding method is explained. A thin product 2 is formed from the product leaving the continuous casting die, which is marked with the number 1 in the drawing. 10 The thin product 2 guided and transported by the traditional support rollers moves from the perpendicular direction through the arcuate part formed by the support rollers to a horizontal position. According to the invention, according to the invention, the thin product of the flat-bed stagnation which takes place at the end of the arc section passes through a first forming step 3, where it is made to a maximum thickness of, for example, 25 nun. The molding step 3 may consist of a single or multi-roll rolling device, preferably a non-rolling arrangement.

For the smoothing of the lamp space, there is a furnace 5 placed in this section, which is preferably equipped with an induction heating device. In this furnace 5, the leveling of the lamp space is simultaneously carried out over the entire cross-sectional area of the thin product 2, so that it arrives at the first rolling chair 6 of the second forming device in a space of sufficient temperature for rolling.

If the blade velocity corresponding to the prevailing speed from the arc section would lead to a significant reduction of the lamp space, resulting in insufficient molding amp-30 space in the second roller chair 7 of the second molding device, a second heating may be designed in the form of a second induction furnace 8 However, the second induction furnace is only necessary in the event that the furnace 5 is not sufficient during the entire molding of the second forming device consisting of three roller chairs 6, 35 7 and 9 to obtain a corresponding decrease in lamp space, that when the last roller chair 9 arrives, the temperature is good enough for molding. Leaving the last roller chair 9, the thin product 2 marked with a ribbon 2 'is now of the desired thickness.

The method ends either by winding the rolled strip 2 'onto the spool 11 and separating it at the device 10 after reaching the desired bundle or roll weight, or by separating the strip 21 to the desired lengths and then stacking it with a stacking device 12 schematically drawn in Fig. 2.

Without the need for additional separation devices, the device 10 for separating the strip can also be used at the beginning of the work step to separate the source blank (not described here), which is separated after it has passed away from the mixed induction furnace 5 and the molding devices 6, 7 and 9. included and mytts off the pan connected to the connected heating device 8 through. Corresponding setting devices have been designed for the device, by means of which the roller die of the starting blank of the starting blank is set to the normal size for molding. In addition, the heating devices 5 preferably consist of zones which are independent of one another, in which case, starting from the initial state of the connected furnace, each furnace zone already bypassed by the batch blank 25 is connected in series to the heating.

Fig. 2 shows, on the basis of a schematic representation (with the same designations) of the individual parts of the device according to Fig. 1, the lamp state of the thin product 2 until the strip 2 'leaves the last roll chair. The Kayråku van alias has a table showing the instantaneous speeds and the corresponding thicknesses corresponding to certain parts of the device and the corresponding parts of the strip. Of course, when the sizes and speeds are different, the lamp flow is different.

II

92161 9

It can be seen from the figure that the thin product 2 from the casting rolling process, having left the first molding step 3, has a temperature of 1075 ° C, which drops to glow flake on the removal device 4 when it reaches 1049 ° C. In this system 5, the removal of the glow flake takes place under pressure water, as a result of which the temperature drops sharply to 969 ° C and cools further when it enters the furnace 5 to 934 ° C.

In the oven or induction heating device 5, the temperature of the temperature rises to 1134 ° C, whereby the leveling of the temperature 10 extends over the entire cross-sectional area of the thin product. THIN PRODUCTS The temperature before the roller stand drops to 6 1104 ° C and is no longer 1063 ° C in the roller stand as a result of contact with the rollers when leaving the roller stand. In the case described, the partially rolled strip is heated in a silently connected induction furnace 8 from 1020 to 1120 eC. When moving to the second roller chair 7, the temperature is 1090 ° C and drops the exit from the roller stand to 1053 ° C until it has dropped to 988 ° C when entering the third and last roller stand 9. 20 This lamp state is a sufficient initial lamp state for the last roll process; exiting the last rolling mill 9, the temperature of the rolling material 2 'is 953 ° C, and as the temperature decreases, it is separated into the desired lengths and stacked or wound as described in Fig. 1.

As for the velocity curve, the velocity in the exemplary embodiment leaving the first molding step 3 is 0.08 m / s or 4.8 m / min. This corresponds to the initial speed when entering the roller chair of the second molding machine, where the thickness of the thin product is still 25 mm. The initial speed on arrival at the rolling mill 7 is 10.2 m / min while the thin product is deformed from 25 mm to 12.3 mm. The rolling material enters the last rolling mill at a speed of 19.8 m / min with a thickness of 6.2 mm and exits the rolling mill at a speed of 30.6 m / min with a thickness of 4.05 mm.

92161 10

As can be seen from the above-mentioned exemplary embodiment, which can in principle be applied to other strip cross-sections, the heating of the first forming device before the first roller chair, possibly the first and other roller chairs, must be effected in such a way that the thin product or rolling is rolled. and the lamp state is kept such that the final rolling temperature on the roller stand does not fall below the limit value of 860 ° C.

In the modified embodiment example illustrated in Fig. 3, a winding and unwinding device 12 is used. As shown in the drawing, the winding and unwinding device is in this case mounted behind an induction furnace 5. the arrangement is supplemented by a glow removal device 4. A thin material is wound on the winding and unwinding device 12 until the desired roll size is reached. Once the wound bundle has been placed in the unloading position (located on the right side of the drawing), the thin material is injected into molding machines 6, 7 and 9 consisting of one or more molding chairs for further purchase. 1, for example with a descending device.

25 Of course, all the variables of the device can influence each other via the casting speed, the rolling speeds and the corresponding formation of the molding. The previous description of the invention has considered the method as well as the equipment necessary for its implementation, which make it possible to continuously cast and final roll the starting product with low equipment costs and with low energy consumption. It has been found that the heating power required for induction heating does not exceed the limit of about 8 MW, which must be considered very economical in a steel plant of this size.

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II

92161 11

According to the invention, the device described for the proposed method and the device required for carrying out the method can be varied within the scope of the invention, in particular radiation ovens, etc.

Claims (16)

92161 12 A method for the continuous production of a steel strip or steel sheet from thin products produced according to the continuous continuous casting method having a horizontal outlet direction, the method being characterized by the following steps: a) forming the thin product (2) after cooling the bottom in an initial molding step (3) b) inductive reheating up to about 1100 ° C with the best possible smoothing of the lamp space over the entire cross-sectional area of the thin product, c) molding of the thin product in at least one other molding step with rolling speeds corresponding to each reduction in thickness. A method according to claim 1, characterized in that the strip is wound during the first and second molding processes. A method according to claim 1, characterized in that the thinly rolled strip is wound and separated from the desired bundle weight into a thin product molding fraction. A method according to claim 1, characterized in that the thinly rolled strip is separated into predetermined lengths of the thin product forming fraction and stacked into steel plate packages, optionally for cooling and straightening. Method according to Claims 1 to 4, characterized in that it undergoes one or more induction selection steps for the thin product in the course of other molding steps. Method according to one of the preceding claims, characterized in that it further comprises the following steps: I! 92161 13 subjecting the molding steps to a blank of the blank formed in the casting process; separating the blank from the blank before winding the tape or separating the plates; 5 separate heating stages in successive stages / chutes after the passage of the blank. Device for carrying out the method according to claim 1, characterized in that it handles the following device parts in the following order: a) a mold (1) for continuous casting of thin products (2) and a subsequent arc-shaped guide stand, b) a first molding device for forming a thin product (c) a device for induction heating and leveling the temperature (5) over the entire cross-sectional area of the thin product (2), (d) at least one other rolling chair (6, 7, 9) and (e) a separating device ( S, 10). Device according to Claim 7, characterized in that the separating device (S) is arranged behind the first molding device (3). Device according to Claims 7 and 8, characterized in that a device for winding and unwinding (12) a thin product is placed in the pile of the first molding device 25 (3) and the other molding device (6, 7, 9), in front of which a separating device (S) is arranged. ). Device according to Claim 9, characterized in that the device for winding and unwinding the thin product (12) is arranged behind the induction heating device (5) and in front of the other molding device (6, 7, 9). Device according to Claim 7, characterized in that a separating device (10) is arranged therein along the rolling strip (2 ') and at least one coil (11) for winding the strip (2'). 92161 14 Device according to Claim 7, characterized in that a separating strip (10) for the strip (2), a cooling device, a straightening roller and a stacking device (14) for the separated plates are arranged behind the device. Device according to Claim 7, characterized in that one induction heating device (8) is provided in addition to the silent heating in the stems of the other roller chairs (6, 7, 9). Device according to Claim 13, characterized in that each induction heating device (5, 8) handles the separately controlled heating steps. Device according to Claim 11, characterized in that it applies an additional device 15 for obtaining a sheet cross-sectional area in the form of rollers and other roller chairs (6, 7, 9) of the forming device (3) to allow passage of the blank from the blank. the molding processes for forming the bay blanket to the required values of 20; it handles the devices for controlling the individual heating steps of the induction heating devices (5, 8) one after the other in order to switch on the lap passage of the blank in each case, and a separating device (10) is used to separate the blank from the roll strip (2 '). Device according to Claim 8, characterized in that the separating device (S) is used for separating the blank. II 92161 15