KR950014488B1 - Method and device for continuously producing steel article by the continuous casting method - Google Patents

Abstract

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Description

Method and apparatus for continuously manufacturing steel products according to the continuous casting method

1 shows schematically a part of an apparatus according to the invention;

2 is a view showing the temperature change of the steel strip to be formed.

3 is a diagram showing a modified embodiment of the present invention.

The present invention relates to a method for continuously producing a steel strip or steel sheet in a flat product produced according to the curved continuous casting method having a horizontal discharge direction.

In the steel industry, there is a need to overcome the risks faced by tenants with outdated equipment over the past few years, or to reduce the administrative and investment costs as a result of the general trend, while at the same time improving the quality of the products and increasing the flexibility of the produced goods, the so-called coils and steel sheets. It has emerged. Modernization of steel fabrication facilities and designs, and the realization of new steel operations by new technical concepts and devices, increase productivity, reduce costs, improve the quality of products, and widen the size range of products, thus making the final product available. Was attempted to achieve optimally.

One of the new technologies that is currently being developed to meet the needs of steel production is to include a machining step between the melting of the steel and i) winding the steel strip in the form of a "coil" or ii) laminating the steel sheet. It involves zipping a thin plate having a near thickness and can be processed through several subsequent operations and forming steps to obtain the desired final product. This has resulted in a notable improvement in continuous casting technology, especially in terms of the mold structure and the corresponding submerged outlet structure, and with the roll stand to achieve the desired molding with as few repetitions as possible. The structure of the roll train was improved.

Although known as `` pilot plant '', steel strip manufacturing equipment is known, in which a thin plate having a thickness of about 50 mm according to the continuous casting method compared to conventional slabs having a thickness in the range of l50 to 320 mm. This thin plate is subjected to a series of rolling and processing steps in various ways, resulting in a steel strip with a thickness of several millimeters, the casting being rolled directly after intermediate heating in a furnace, for example six stands. The rolling speed at the last stand of the roll train is too low to maintain a final rolling temperature above 865 ° C. because the casting speed is not faster than about 5 m / min.

That is, the strip is excessively cooled by a low speed that coincides with the casting speed upon entering the roll train between one rolling step and subsequent steps. Thus, having a thermal protection device and heated rolls to solve this problem was abandoned because it was not an economical solution because of the significant increase in investment and operating costs.

Another solution is to cut the strip in front of the furnace, in which the heat treatment (temperature equalization) of the strip is then carried out across the shear plane. This can be for example a gas heated rolling furnace (Rollenfen), whereby the strip can be adjusted to a temperature of about 110 ° C. at the outlet of the furnace, regardless of the considered casting speed, which is followed by a subsequent rolling process. Is the optimal temperature. The strip can be cut, for example, to a standard length, which can be 50 m for a given coil weight and a furnace length of about 150 m is required when the necessary cushioning action is taken into account.

By separating the roll train during the actual casting process, the rolling of thin plates or prestrips can be carried out at high speeds and the temperature does not drop below the minimum temperature allowed for the final rolling step. The result is an excessively long furnace length, which is about three times the length of the strip fragments, which not only significantly increases the capital investment, but also requires the need for a huge place that cannot be satisfied in many steel mills.

The size of the installation and furnace thus limits the continuous length of the strip pieces to be processed and the final coil weight, which also limits the production range of very large diameter coils. Therefore, thinner initial plates cannot be produced in the above installations, which must be made possible through further development of the continuous casting method. As already assumed, assuming an initial thickness of 25m instead of 50m, the strip should be divided into lengths of about 100m in order to have the final weight of the same coil, which requires about 300m for processing furnaces. It is neither enemy nor economic.

It is an object of the present invention to produce a steel strip continuously in a flat product obtained from a curved continuous casting plant which does not exhibit the above-mentioned disadvantages in order to solve the problems of the method according to the known art and the apparatus for carrying out the method. And to provide an apparatus.

In particular there is no cutting of the strip between the casting process and at least the first rolling process, and the strip rolled at a speed equal to the bend of the continuous casting plant passes through the first roll stand. Thus, the process according to the invention is carried out in line `` in line '' with virtually unlimited flexibility, so that a coil or sheet having a predetermined weight and length can be produced without changing the size parameters of the installation, This is because the cutting of the rolled strip takes place immediately before the winding device or lamination device after at least the first rolling process or after carrying out all operations.

The object according to the invention is a) molding a flat product at a temperature of at least 1100 ° C. in a first molding step after expiration of solidification of the casting, and b) temperature equalization and about 1100 ° C. over the entire cross section of the product. Induction reheating to a temperature of and c) shaping said product in at least one further shaping step at a rolling speed corresponding to the reduction during passage of the rollers.

In the embodiment according to the invention, the strip is wound between the first molding process and the further molding process. The rolled strips corresponding to the desired coil weight can be wound in connection with the shaping of flat products or the steel sheets can be laminated according to cooling and orientation after cutting of the rolled strips in connection with the shaping of flat products of a given length. The product first passes through the first roll stand at the rate of outflow of the product from the curved continuous casting plant and then undergoes a continuous rolling step at a rate corresponding to the deformation during each roll pass. The rolled strip is then wound up, cut or divided into desired lengths and laminated into plates after reaching the desired coil weight. An important feature of the present invention is the induction reheating of the flat product to a temperature of 1100 ° C. for optimal temperature uniformity after removing the scale, whereby excessive cooling of the strip can be well prevented.

In yet another embodiment of the present invention, one or more steps are provided for inductively heating the product in between the forming steps. This intermediate heating step prevents excessive cooling of the rolled product so that it can always be adjusted to the required rolling temperature and the temperature in the final forming step does not fall below the threshold of 860 ° C.

According to another embodiment of the present invention, there is provided a method of controlling a forming step after passing an initiation bar provided in a casting process; Separating the initiation bar immediately before winding the strip or laminating the plates; It is further provided to control heating distinctively in successive steps / zones after passage of the initiating bar.

The initiation bar may be cut into a cutting device after passing through the roll stand and by another cutting device placed after the first molding step.

The equipment for carrying out the method according to the invention comprises: a) a mold for continuously casting a flat product comprising a guide stand of a curved shape. b) a first forming part for shaping a flat product at a guide stand and / or a position immediately following it, c) a device for uniformizing and induction heating the temperature across the shear surface of the product, d) at least one another And a roll stand and e) a cutting device.

The cutting device is arranged after the first molding device, between the first molding device and another molding device, and may be provided with a device for winding and unwinding the flat product, which is disposed in front of the cutting device. This winding and unwinding device can be arranged behind the induction heating device and in front of another forming device.

According to another embodiment according to the invention, a cutting device for a rolled strip and at least one reel for winding the strip are stacked or a cutting device for a rolled strip, a cooling device, a straightening device and a separate plate are laminated. The lamination apparatus can be arranged continuously.

In a further embodiment of the invention, the installation according to the invention further comprises at least one induction heating device for intermediate heating between different roll stands.

Each device preferably includes a heating unit that can be adjusted separately.

According to another preferred embodiment of the present invention a passing cross section can be passed between the roller of the first forming apparatus and another roll stand so that the initiation bar in front of the casting strand can be passed through and the cross section can then be returned to the normal pass value. A device for adjusting is further provided. A device is provided for continuously adjusting the heating portion of the furnace immediately after passing through the initiation bar, the apparatus for cutting the initiation bar being used to cut the rolled strip, ie the cutting device arranged in the final part of the installation according to the invention. Used as

In another embodiment of the present invention, a cutting device disposed behind the first forming portion is used for cutting the initiation bar. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

With reference to the drawings, a plant according to the invention is shown schematically, with reference to this drawing a continuous manufacturing method according to the invention is described. The flat product 2 emerges from the continuous casting mold indicated by reference number 1. The flat product 2 which is guided and conveyed by the usual support roller is guided and transported from the initial vertical direction to the support roller and the flat product 2 which is moved from the initial vertical direction to the horizontal direction through the bent portion formed by the support roller. do. It is moved at the end of the bend, in which the product reaches an inner thickness of 25mm. The shaping part 3 preferably consists of one or more roll devices arranged in quadruple form.

A furnace 5 is provided for temperature equalization, which is preferably configured to have an induction heating device. In this furnace 5 the temperature is homogenized over the front end face of the product 2 so that it has a sufficient rolling temperature and the product reaches the first stand 6 of another forming apparatus.

If the initial speed is considerably slower in response to the speed at the time of discharge from the bend, the temperature is drastically lowered, so that an insufficient molding temperature is generated in the second roll stand 7 of another forming apparatus, and between the stands 6 and 7 of the roll is produced. Another heating device in the form of a two-induction furnace 8 is provided, which is shorter than the furnace 5. However, this second induction furnace is necessary when the furnace 5 is not sufficient to achieve a suitable temperature gradient during molding along another forming apparatus consisting of three roll stands 6, 7, 9, and the last When entering the roll stand 9 the temperature is in a temperature range sufficient to mold well. The product 2, represented by the strip 2 ′, when discharged from the roll stand 9, has the desired thickness.

In accordance with the present invention, when the predetermined coil weight is reached, the rolled strip 2 'is wound on the reel 11 and cut at 10 or the strip 2' is cut to a desired length and laminated to the lamination apparatus. This is illustrated in FIG. 2 schematically.

An apparatus for cutting the strip 10 at the beginning of the operating cycle without the need for an additional eye cutting device can be used to cut the start bar, not shown, which is used in the shaping device 6, 7, 9. After passing through a blocked induction furnace 5 and an open roll, it is cut after passing through a blocked intermediate heating device 8 which may be provided. A corresponding adjusting device (not shown) is provided, which immediately adjusts the roll to the shape of the normal roll nip required for shaping, immediately after the opening bar passes.

The heating device (induction) 5 also preferably consists of zones independent of each other, and thus proceeds from the blocked state of the furnace, and the furnace zones each passed by the initiation bar are heated in turn.

On the basis of the diagram schematically showing the individual parts of the installation according to FIG. 1, FIG. 2 shows the temperature curve of the flat product 2 from the last roll stand to the discharge of the strip 2. Below this temperature curve is shown a table, which describes the respective speeds and corresponding thicknesses corresponding to the predetermined parts of the plant according to the invention and the corresponding strip parts. The indicated values were experimentally obtained in strips with a width of 1000 mm and a thickness of 20 mm. Of course, different temperature curves appear at different sizes and speeds.

Referring to the drawings, the product 2 produced by the casting rolling process has a temperature of 1075 ° C. when discharged from the first molding part 3, which is lowered to 1049 ° C. on the way to the descaling device 4. By descaling with this arrangement, the temperature is lowered to 969 ° C and cooled to 934 ° C on the way to the furnace 5.

In the furnace or induction furnace 5 the temperature is again raised to 1134 ° C. to achieve temperature uniformity across the shear surface of the flat product. Before reaching the roll stand 6, the temperature is lowered to 1104 ° C., which reaches 1063 ° C. by contacting the roll of the roll stand as it exits the roll stand. In this case the partially rolled strip is heated to 1120 ° C. at 1020 kPa in an intermediate induction furnace 8. When passing through the second roll stand (7) the temperature is 1090 ℃ and when leaving the roll stand is lowered to 1053 ℃ and when entering the third and final roll stand (9) is lowered to 988 ℃.

This temperature is sufficient as the initial passage temperature of the final rolling process. The rolled strip 2 ′ is discharged at a temperature of 953 ° C. in the final roll stand 9 and then cut to the desired length at the lowered temperature and laminated or wound as shown in FIG. 1.

As for the speed change, the speed when leaving the first forming part 3 in the disclosed embodiment is 0.08 m / sec, ie 4 8 m / min. This speed coincides with the passage speed when entering the roll stand of another forming apparatus, where the flat product is 25 mm thick. The passage speed when entering the roll stand 7 is 10.2 m / min, and at the same time, a product having a thickness of 25 mm is molded into 12.3 mm. With the final roll stand, the rolled product flows in at a speed of 6.2 mm at a speed of 19.8 m / min, and the product passes through at a thickness of 4.05 mm and a speed of 30.6 m / min.

As can be seen in the above-described embodiment, the present invention can also be applied to the case having other strip cross sections, and the intermediate heating between the first roll stand and another roll stand of the first roll stand of another forming apparatus is performed by the first roll stand. After passing, the heating of the flat product, ie, the rolling strip, is controlled to remain on at 1100 ° C. and at the final roll stand so that the final rolling temperature does not drop below the limit of 860 ° C.

In the variant embodiment shown in FIG. 3 a winding and unwinding device 12 is used. As shown in the figure, the winding and unwinding device is provided behind the induction furnace 5. This arrangement is complemented by the descaling device 4. The reel of the winding and unwinding device 12 is wound into a flat strip until the desired coil size is reached. The wound coil is moved to the unwinding position (right side of the drawing) and the flat stall is fed to the roll stand 6, 7, 9, which is another forming device consisting of one or more forming structures for further processing. If necessary, an additional induction furnace 8 can be installed between the roll stands of another forming apparatus. The final coil is made on the reel 11, for example on a down coiler.

All parameters according to the invention are of course influenced by each other by appropriately adjusting the casting speed, rolling speed and deformation.

The foregoing description discloses the method according to the invention and the equipment required to carry out the method, which are low in equipment cost, low in energy and enable the continuous production and final rolling of the product. The heating output required for induction heating should not exceed the limit of about 8 MW, which makes it clear that it is economical for a Zhejiang manufacturing plant.

The method according to the invention described above and the equipment for carrying out the same can be modified and modified within the scope of the invention, in particular the heating device provided between the roll stands in front of the roll train can be replaced by a known induction furnace and the laser A furnace with a technique, a copy furnace, or the like can be used.

Claims (17)

A method for continuously producing a flat steel product from a flat product manufactured according to a curved continuous casting method having a horizontal outflow direction and a starting bar shape, comprising: a) 1100 ° C. or more in the first molding part 3 after solidification of the cast product; Reducing the thickness at temperature to form a flat product, b) induction reheating to a temperature of about 1100 ° C. while equalizing the temperature across the entire cross section of the product, and c) rolling corresponding to a reduction in thickness during the passage of the roller. Forming the product in at least one further forming step at a speed. The method of claim 1, wherein the step of winding the steel product comprises a step between the first forming step and the further forming step. The method of claim 1, comprising winding the steel product after further molding of the flat product, and cutting the steel product to correspond to the desired coil weight. 2. The method of claim 1 comprising the step of cutting the steel product to a given length after laminating the flat product and laminating the cut steel product. 5. The method of claim 1, comprising one or more steps of inductively intermediate heating of the flat product during further forming steps. 6. The method according to any one of claims 1 to 4, further comprising the steps of: adjusting the forming step after passing of the initiation bar included in the casting process; Cutting the initiation bar immediately before winding or cutting the flat steel product; And optionally adjusting the reheating in a subsequent forming step after passing the initiation bar. An apparatus for continuously producing steel products for carrying out the method according to claim 1; a) a mold 1 for continuously casting a flat product 2 having a curved guide stand; b) a first molding part for molding a flat product directly to the guide stand; c) an apparatus 5 for homogenizing and induction heating the temperature across the shear surface of the article 2; d) at least one other roll stand 6, 7, 9; And e) a cutting device (S, 10). 8. Device according to claim 7, characterized in that the cutting device (S) is arranged behind the first forming part (3). Apparatus (12) according to claim 7 or 8, which winds and unwinds a flat product disposed in front of the cutting device (S) between the first forming portion (3) and the roll stands (6,7, 9), which are additional forming apparatuses. Apparatus for continuously manufacturing steel products, characterized in that the provided. 10. The method according to claim 9, characterized in that the winding and unwinding device (12) is arranged in front of the roll stands (6, 7, and 9), which are additional forming devices behind the induction heating device (5). Device. 8. The continuous production of steel products according to claim 7, characterized in that the cutting device 10 for the steel strip 2 'and the at least one reel 11 for winding the steel strip 2' are arranged one after the other. Device. The steel product according to claim 7, wherein the cutting device 10 for the rolling strip 2 'and the reel 11, which is a laminating device for laminating a cooling device, an orientation roll, and a cut plate, are sequentially arranged. Device for continuous production. 8. Apparatus according to claim 7, characterized in that at least one induction heating device for intermediate heating is further provided between additional roll stands (6,7,9). 14. Apparatus according to claim 13, characterized in that each of the induction heating devices (5, 8) comprises a separately adjustable adjustable heating section. 12. The passing cross section between the rolls of each of the forming sections 3 and the rolls of the other roll stands 6, 7, and 9 so as to allow the initiation bar to pass from the flat product. Means for adjusting the passage cross section to the cross section required in the molding step of the product produced continuously through the casting method after the passage; Means for operating the heating devices 5, 8 immediately after passing through the initiation bar to adjust the heating devices; And means provided therein for cutting the starting bar. 10. The apparatus of claim 8, further comprising a cutting device (S) for cutting the initiation bar. 6. The method of claim 5, further comprising the steps of: adjusting the forming step after the initiation bar involved in the casting process; Cutting the initiation bar immediately before winding or cutting the flat steel product; And optionally controlling reheating in a subsequent forming step after passage of the initiating bar.