RU2405639C1 - Method of producing lot of hot-rolled sheets - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method comprises producing slabs at continuous casting machines (CCM), their heating, rolling and cutting rolled stock into sheets of preset sizes. Proposed method comprises allowing for preset weight of the lot, determining the weight of one sheet P₁ and probable number n of sheets in the lot equal to n=(P-ΔP₁)/P₁…(P+ΔP₂)/P₁. Then for every integer n cut multiplicity is determined, i.e. K_i=K₁×K₂, where K_i is the number of sheets produced on cutting the rolled stock produced at CCM with due allowance for slab standard sizes, K₁ is tolerable number of sheets in cutting sheets in crosswise direction, and K₂ is tolerable number of sheets in cutting in lengthwise direction. Then for each K_i, proceeding from possible load-lifting capacity, tolerable slab weight is determined, i.e. P_{slab i}=k_cons·K_i·P₁, where k_cons=1.011…1.274 is coefficient of materials consumption. Then complying with minimum value of said coefficient of materials consumption and minimum tolerable surplus amount of precut sheets, and process limitations of equipment, maximum multiplicity of cutting is set, i.e. K_i=K_max, and optimum slab weight P_{opt slab}=k_cons·K_max·P₁ is determined to satisfy aforesaid conditions. Slabs are produced at CCM equipped with crystalliser with cross section satisfying the requirement of producing optimum weight slabs, i.e. P_{opt slab.}

EFFECT: minimised wastes in production of lots, higher quality.

4 ex

Description

The invention relates to rolling production and is intended to optimize the process of hot rolling of sheets.

The problem of creating non-waste technologies or reducing the consumption of source material in the manufacture of finished products is relevant for many industries.

For example, in light industry, to reduce the complexity and consumption of roll or sheet material, a method of preparation for cutting roll and sheet materials is used (RU 2329750 [1]). According to this method, each part or group of pre-joined parts of a cut is represented as a rectangular part, which is a rectangle oriented relative to the warp thread, the middle between the described and inscribed maximum area of the rectangles with respect to the part or group of parts of the cut. A sequence is formed, one after the other, in accordance with a decrease in their length of the rectangular parts selected as the determining parameter, and its total width is measured. The number of columns of rectangular parts is determined, and the column is a set of rectangular parts arranged in one row along the entire width of the layout frame of the layout by dividing the total width of this sequence by the width of the layout frame. The width of each column is determined and the length of the material to be cut is estimated as the sum of the lengths of the columns. Consistently fill the area of the material being cut in the columns with rectangular parts so that the rectangular part with the smallest length at the end of one column is located next to the rectangular part of the greatest length at the beginning of the adjacent column.

However, this method cannot be applied in metallurgical production, in particular in the manufacture of hot-rolled sheet.

A known method of cutting and manufacturing blanks of parabolic mirrors for receiving solar energy from sheet materials, which includes the calculation and marking of the circle with concentric circles. The circle is then cut out, and concentric circles are cut into half the thickness of the sheet. A profile sector is cut from the circle. Next, the rest of the circle is bent until the sides touch to obtain a rotation paraboloid. The parties to the sector weld and strip the seams (RU 2134174 [2]). However, this method cannot be applied in metallurgical production for cutting, in particular in the manufacture of hot-rolled sheet.

A known method of optimizing the cutting of rolled products, which is described in patent RU 2278768 [3] and is implemented using the corresponding device. A device for scissors of a rolling mill for optimal cutting of rolling stock includes a length meter of the roll before the finishing group of stands based on sensors for continuous tracking of the roll, sensors of the presence of rolling on the axes of the stands of the finishing group, a tracking drive roller, a sensor for converging the knives of flying shears, a tracking drive of flying shears and a computing block. The device further comprises a meter for the length of the roll at the exit from the roughing group of stands based on the sensor for the presence of roll in the axis of the last stand, at least one sensor for the position of the roll, giving a signal about the presence of roll in the computing unit, a device for measuring the cut stock after flying scissors, consisting of the information processing unit, the measuring chamber and at least one position sensor of the cut-off workpiece, while the output of the sensor is connected to the input of the measuring chamber, and the output of the measuring chamber is Dinan with the input of the information processing unit, the output of which is connected to the input of the computing unit, the camera in front of the finishing group of stands, which sends a signal about the amount of stripping of the “head” of the roll to the information processing unit, while the computing unit is based on a programmable controller. The technical result is an increase in yield by non-waste cutting from the first workpiece.

The method is implemented as follows. Using the roll position sensor, the time for the roll to pass through the last stand of the roughing stand group is determined. The camera, installed in front of the finishing group of stands, sends a signal about the amount of stripping of the “head” of the roll to the information processing unit, where the length of the roll at the entrance to the finishing group of stands is calculated.

As rolling stock in the finishing group of stands, according to the data from the sensors of the position of rolling in the computing unit, the drawing coefficients of stands of the finishing group are calculated.

Based on a preliminary measurement of the length of the roll and the drawing coefficients, the length of the roll in the output section is calculated.

The length of the roll is used to calculate the cutting plan before the start of the cutting cycle of the roll on flying scissors, in case the length has not yet been calculated. Based on the length of the roll at the exit of the finishing group of stands, the computing unit calculates the cutting plan for cutting the roll in a given range of lengths with flying scissors.

Based on the calculated cutting plan, the computing unit generates a task to drive the flying scissors, and for each new workpiece separately.

The length of the workpiece being cut by flying scissors is measured by the device for measuring the cut workpiece. Measurement is as follows. The measuring chamber receives signals from the sensors and, if at the moment of operation of one of them the tail of the workpiece is in the camera’s field of view, the frame is captured, fixing the coordinate of the rear end of the workpiece. Thus, knowing the coordinate of the rear end of the workpiece and the distance between the sensors and the camera, as well as the number of the triggered sensor, the actual length of the workpiece is determined in the information processing unit. This information is sent to the computing unit, where, based on the difference between the given and actual lengths, the correction to the flying scissors drive is calculated to ensure optimal cutting of the rental.

The disadvantage of this method is the relatively high waste to trim. This is due to the fact that the ready-made peal is subjected to the calculation of cutting and the cutting itself, when it is already impossible to make any changes to its size. In addition, it is possible to obtain extra sheets that are not designed to order.

Closest to the claimed method in its technical essence is a method of cutting metal, including rolling the workpiece on a workpiece mill for a given section, after which the resulting workpiece is cut into pieces (RU 2112611 [4]). Then they are rolled on a section rolling mill to the next predetermined section, the resulting metal rolling is cut into products (rods), cooled, packaged, then the bundle of rods are cut into final measured lengths.

Before this, the volume of the product (bar) of the final measured length is determined and after rolling the billet on the billet mill, its linear dimensions are measured and its volume is determined. The billet is cut on a blanking mill into parts whose volumes are multiples of the volume of the product (bar) of the final measured length, taking into account technological waste, then the billet is rolled on a section rolling mill, the linear dimensions of the rolled metal are measured and cut into parts (rods) whose dimensions (lengths) are multiple final measured length taking into account technological waste when cutting.

The disadvantage of this method is that it is applicable to cutting only long bars, i.e. taking into account only two dimensional parameters - the diameter of the cross section and length. At the same time, when cutting, restrictions on the batch weight of a given size of products (bars), the number of products in the batch corresponding to the weight of the order are not taken into account. In addition, the known method does not provide for variations in the size of the initial blanks, which are then cut into blanks for a section rolling mill. The known method does not take into account the restrictions imposed by the equipment used.

When rolling hot rolled sheets of relatively large thickness and area, a number of problems arise. Firstly, orders for sheets are placed in batches in the indicated tolerances for the weight of the batch. The sheets and blanks from which they will be rolled (slabs) in different lots have different sizes and weights.

If you roll a sheet for an order with the maximum productivity that the available equipment allows, then in some cases it turns out that the number of rolled products (sheets) and their total weight are more than necessary for the customer. As a result of this, products having a large metal consumption and correspondingly cost accumulate in the finished goods warehouse, which, if they do not find their consumers, are ultimately sent to redistribution, which entails significant economic costs. Therefore, to reduce these costs, it is advisable to initially evaluate and select the number of sheets in the batch, taking into account the tolerance on the weight of the batch, and also select blanks (slabs) of such sizes and weights that the number of sheets in the batch is a multiple of the number of sheets obtained from one blank, which, on the one hand, it will ensure maximum productivity of the rolling mill, and, on the other hand, it will not lead to the formation of "extra" measuring sheets.

Maximum productivity is achieved when the whole batch of sheets (products) necessary for the customer can be made from one billet (slab). However, given that the weight of one sheet can be several tons, their number in a batch is several tens, and the weight of a batch can be hundreds of tons, the capabilities of technological equipment become a limiting factor in achieving maximum productivity. For example, it is impossible to get rolled wider than the length of the rolls of the rolling mill, it is impossible to get a roll of longer length than the lengths of the inlet and outlet roller tables (about 50 m). It is impossible to make a workpiece weighing more than the permitted lifting capacity of cranes (about 30 tons). In addition, the design of the heating furnace itself will not allow placing a workpiece with a length of more than 4.8 m inside it.

As a result, it is necessary to solve a rather complex multicriteria optimization problem, which consists in the fact that many requirements must be taken into account:

- to ensure maximum productivity of the mill, and for this to use, if possible, the workpiece of the greatest weight;

- ensure accurate (by the number of sheets) order fulfillment or, if this is impossible, to the detriment of productivity - the minimum excess of the number of measured sheets in excess of the required quantity in a batch;

- take into account the technological restrictions imposed by equipment and rolling technology on the mill;

- but even if the thickness of the sheets is large enough and a roll can be made from a workpiece sufficient to cut it into the number of sheets in accordance with the order, it may turn out that the crane will not be able to move it to the heating furnace or the furnace will not be able to accept such a workpiece.

At the same time, it is also necessary to take into account the fact that it is advisable to reduce losses associated with the waste to technological scraps, and for this it is necessary to pour such blanks (slabs) from which you can get an integer number of products (sheets) adjusted for technological losses. All known technical solutions in the field of cutting sheet material or cutting metal products do not take these restrictions into account.

The inventive method of manufacturing batches of hot-rolled sheet is aimed at minimizing waste in the manufacture of a given number of sheets in the ordered batch and reducing residues of non-order products in warehouses.

This result is achieved by the fact that the method of manufacturing batches of hot-rolled sheet includes producing slabs on continuous casting machines (CCM), heating, rolling and cutting the resulting roll into sheets of predetermined sizes, while taking into account the set batch weight within the tolerances of P-ΔP ₁ ... P + ΔP ₂ , where ΔP ₁ and ΔP ₂ are negative and positive tolerances on the weight of the batch, pre-determine the weight of one sheet P ₁ and the corresponding possible number of sheets n in the batch, equal to n = (P-ΔP ₁ ) / P ₁ ... (P +? P ₂₎ / P _1, and then for each purpose th n determined multiplicity cutting K _i = K ₁ × K ₂ where K _i - the number of sheets obtained by cutting of roll produced from the obtained in CCM slab, with the sizes of slabs, K ₁ - permissible number of sheets when slitting peal in the transverse direction, and K ₂ - the permissible number of sheets when cutting the roll in the longitudinal direction, for each of the obtained values of K _i determine, based on the conditions of the possible lifting capacity of the cranes, the permissible weight of the slab P _{slab i} = k _pacx · K _i · P ₁ , where k _pacx = 1,011 ... 1,274 - expense coefficient taking into account technological losses and metal, then, subject to the conditions of the minimum value of the expenditure coefficient and the minimum excess of the number of measured sheets in excess of the required number in the batch, taking into account the technological limitations of the equipment, set the maximum multiplicity of cutting of the roll K _i = K _max and determine the optimum slab weight P _opt satisfying these conditions _{. slab} = k _pacx · K _max · P ₁ , and slabs are produced on a continuous casting machine, which is equipped with a mold, the cross-sectional dimensions of which correspond to the condition for producing slabs with an optimal weight equal to P _Opt . _slab .

The calculation of the range of number of sheets in the batch, taking into account the tolerance on the batch weight, is necessary so that during production there are no residues in the sheets at the finished goods warehouse, in excess of the required sheets on order. In this case, according to the order, different negative and positive tolerances for the lot weight can be set or only one of them can be set. Variation of the number of sheets in the calculation range allows you to choose the number of slabs (peals) at which a multiple number of sheets is obtained from each or, if this is not possible, to ensure a minimum excess of measured sheets over the required number in the batch.

Using for this purpose, as a criterion, the possibility of obtaining from each of the slabs a multiple number of sheets with minimal waste to trim also optimizes the cutting of the roll, because the size of the trim depends on the size of the roll and the ratio of compression in the longitudinal and transverse directions. After calculating the amount of trim for each of the cutting options, the optimal slab size is selected with a minimum cost factor for trimming. At the same time, taking into account the condition of the minimum value of the expenditure coefficient and the minimum excess of the number of measuring sheets in excess of the required quantity in the batch, taking into account the technological limitations of the equipment, it is possible to choose the most optimal option. Indeed, the dimensions of the end and end trimmings do not depend too much on the size of the roll, therefore, for the roll and, accordingly, the workpiece of greater mass, the expenditure coefficient will be smaller than for the roll of smaller geometric dimensions and weight. Therefore, in some cases, it is advisable, with a larger increase in the number of measuring sheets in excess of the required quantity in the batch, to choose a slab of greater mass, which allows for large-sized rolls, thereby reducing the expenditure coefficient.

In this case, when calculating the number of slabs and obtaining from them a multiple number of sheets, it is necessary to take into account the technological limitations of the equipment used, for example, a roller table. Indeed, if we take into account that the length of the roller table is fixed, then the size of the slab must be selected so that the roll obtained from it does not extend beyond the roller table. Especially this circumstance must be taken into account when reversing rolling, when the roll obtained from one slab must cool in air before re-passing through the stand, and at this time the next slab is rolled. Another limiting factor is the design of the heating furnace. It limits the permissible minimum and maximum lengths of the slabs, since a short slab can fall between the beams of the heating furnace, and too long a slab simply will not fit into the furnace. The roll barrel size also limits the size of the slab, since when rolling sheets from narrow slabs, an important factor is the ability to rotate it 90 ° for rolling in the transverse direction. Therefore, the length of the slab cannot exceed the size of the barrel roll of the rolling mill. The longest and widest slab can exceed the permissible lifting capacity of the cranes in the slab storage area, which must also be taken into account. In addition, the width of the slab cannot be greater than the width of the roll, because due to rolling, with a decrease in thickness, the width and length of the roll can only increase.

In preparing the calculation of cutting, it is important to take into account the expenditure coefficient, which takes into account the technological losses of the metal, since the dimensions and weight of the slab, and, therefore, the technological limitations of the equipment used, will depend on it. In particular, the permissible weight of the slab based on the capacity of the _slab crane P _i = k _pacx · K _i · P ₁ , where k _pacx = 1.011 ... 1.274 is a consumption coefficient taking into account the technological losses of the metal. The values of k _pacx = 1.011 ... 1.274 are due to the specifics of the production of plate products. Indeed, the expenditure coefficient of the metal is the ratio of the mass of the original billet (slab) to the mass of suitable metal G _g . According to the literature (Konovalov Yu.V., Ostapenko A.L., Ponomarev V.I. Calculation of the parameters of sheet rolling. - M .: Metallurgy, 1986. - 430 p. [5], Technology of rolling production. In 3 books, Book 1. Reference book / M. Benyakovsky, K. N. Bogoyavlensky, A. I. Vitkin et al. - M .: Metallurgy, 1991. - 440 p. [6]) taking into account the main articles of metal consumption when it is processed on a plate mill, the expenditure coefficient can be represented as follows:

, где

where

k _ok = 1,011 ... 1,032 - coefficient of metal flow into the scale;

k _to = 1,050 ... 1,100 - coefficient of metal flow to the end (end) trim;

k _bo = 1,050 ... 1,100 - coefficient of metal flow to the side trim;

k _ol = 1,001 ... 1,020 - the coefficient of metal consumption for samples for testing the properties of the metal.

Based on the data presented, the minimum value of the expenditure coefficient is 1.011, as the minimum rate of metal consumption in burns, if the metal is ordered without trimming the edges (a common case in plate production).

The maximum value of the expenditure coefficient can be considered the product of the largest values included in it: 1,032 · 1,1 · 1,1 · 1,02 = 1,274.

In the absence of the required standard sizes of slabs needed to obtain a given batch of sheets with minimal waste, it is advisable to cut the slabs of the required sizes from those available. At the same time, the size of the slab to be cut should be chosen so that it is possible to produce a multiple number of sheets with minimal scrap waste and at the same time eliminate the slab waste.

The essence of the proposed method is illustrated by examples of its implementation.

Example 1. In the most general case, the method is implemented as follows. Having received an order for the manufacture of a batch of sheets, first determine their quantity in the batch. For this, the weight of the batch, taking into account negative and / or positive tolerances, is divided by the predetermined weight of one sheet and the number of sheets that will make up the batch is obtained.

Then, for each of the possible values of the integer number of sheets in the batch, the allowable multiplicity of cutting of the roll is determined, which is the product of the number of sheets that can be obtained when cutting in the transverse direction and the number of sheets that can be obtained when cutting in the longitudinal direction. At the same time, technological limitations associated with equipment are taken into account, such as the length of the inlet and outlet rolling rolls of a rolling mill, the length of a roll of rolling rolls, and the limitations associated with the design of scissors for longitudinal and transverse cuts.

Next, for each of the obtained values of the permissible cutting ratio, the allowable weight of the slab is calculated, which is the product of the nominal expenditure coefficient, the cutting ratio and the mass of one sheet. The expenditure coefficient is in the range from 1.011 to 1.274 and takes into account the loss of metal for technological cutting, sampling and burning. Then the weight of the slab is checked for the condition of the crane capacity and obviously unsuitable options are screened out. Taking into account the available cross-sections of the molds, the continuous casting machine determines the permissible dimensions of the slab that satisfy the restrictions associated with the design of the heating furnace and rotary tables.

Then, from the possible multiplicities, the maximum is selected, which will provide the minimum value of the real expenditure coefficient and the minimum number of measured residues formed in excess of the required quantity in the batch. After this, the sizes and weight of the slab that are appropriate for such a cutting are finally selected. After the relevant restrictions have been taken into account and the required number of slabs and their sizes have been calculated, the selected or manufactured (cut) slabs are placed in a heating furnace and heated to the optimum temperature necessary to feed the slab into the mill stand. Then the heated slab is moved to the mill, where it is rolled to produce a roll of a given thickness. The finished roll is cut in a known manner and using known equipment (based on the available equipment, only one longitudinal cut is possible). The result is a batch of sheets with a given number or with a minimum excess over a given one and with minimal waste to trim.

Example 2. Having received an order for the manufacture of a batch of sheets, first determine their quantity in the batch. An order was received for the production of a batch of sheets with a total weight of 100 tons and a sheet size of 18 × 1750 × 12000 mm. Based on the geometric dimensions and specific gravity of the metal, we determine the mass of one sheet, which in this case will be about 3 tons. Given the tolerance on the order value of ± 5%, the weight of the finished product can vary from 95 to 105 tons. Based on the weight of the sheets, weight parties taking into account the need to obtain only an integer number of sheets can be 96, 99, 102, 105 tons. Accordingly, the number of sheets in a batch can be 32, 33, 34 or 35 pieces.

Based on the existing restrictions on the mass of the slab, which is 5.2 t for a slab of a minimum size of 190 × 1400 × 2500 mm, and 30.4 t for a slab of a maximum size of 300 × 2700 × 4800 mm, and taking into account the crane lifting capacity of 30 t the number of whole sheets obtained from one slab can be from 2 (6 tons) to 10 (30 tons) sheets.

At the same time, when choosing the sheet multiplicity - the whole number of sheets, which can be obtained by dividing one roll (slab), it is necessary to take into account the technological restriction on the rolling table of the mill, according to which, the length of the roll cannot exceed 52,000 mm. Based on this restriction and the length of the ordered sheets, the multiplicity along the length of the roll cannot exceed 4 (4 × 12000 = 48000 <52000 mm).

At the same time, the possibility should be taken into account that in this case it is possible to cut the roll lengthwise, since the width of the ordered sheet is 1750 mm and the working length of the roll barrel is 4800 mm. That is, the width multiplicity can be 2.

For a batch of 32 sheets, a multiplicity of 1 × 2, 2 × 1, 2 × 2, 4 × 1, 4 × 2 will be possible, where the first digit shows the possible number of sheets in the roll in the longitudinal direction, and the second in the transverse. For a batch of 33 sheets, a multiplicity of 3 × 1 will be possible. For a batch of 34 sheets, a multiplicity of 2 × 1 will be possible. For a batch of 35 sheets, not a single multiplicity is possible.

For each of these multiplicities, the weight of the slab is determined at a nominal value of the expenditure coefficient equal to 1.087. The obtained values are analyzed on the condition of the permissible carrying capacity of cranes (<30 t), and the sizes of slabs corresponding to these values are analyzed on the conditions of the limited design of the heating furnace and rotary tables of length (<4800 mm) taking into account the available sections of the molds of the continuous casting machine.

The multiplicity of cutting 4 × 2 sheets does not exceed the number of sheets in excess of the required in the batch (32 sheets = 4 rolls, cut into 4 sheets along and 2 sheets across) and is the maximum possible, subject to all these restrictions. Accordingly, it meets the conditions for maximum productivity of the rolling process.

For this case, the optimal mass of the slab will be 26.088 tons.

The sections of the molds of the continuous casting machine (CCM) in this particular case are possible combinations of thicknesses 190, 250, 300 mm and widths 1400, 1560, 1650, 1730, 1850, 2030, 2300, 2700 mm. Since the length of the slab should not be less than 2500 and more than 4800 mm (the restriction imposed by the design of the furnace), such a cross section is selected that provides the required mass of the slab under the conditions along its length. The calculation shows that this can only be 300 × 2700 mm. The length of the slab will be 26.088 / (0.3 × 2.7 × 7.82) = 4120 mm.

Example 3. An order was received for the production of a batch of sheets with a total weight of 65 tons and a sheet size of 20 × 1500 × 6000 mm. Based on the geometric dimensions and specific gravity of the metal, we determine the mass of the sheet, which in this case will be 1.413 tons. Given the tolerance on the order value of ± 5%, the weight of the finished product can vary from 61.75 to 68.25 tons. Based on the weight of the sheets , the batch weight, taking into account the need to obtain only an integer number of sheets, can be 62.172; 63,585; 64,998; 66,411 or 67,824 tons. And accordingly, the number of sheets in the batch will be 44, 45, 46, 47 or 48 pieces.

Based on the existing restrictions on the mass of the slab, which is 5.2 t for a slab of a minimum size of 190 × 1400 × 2500 mm, and 30.4 t for a slab of a maximum size of 300 × 2700 × 4800 mm, and taking into account the crane lifting capacity of 30 t the number of whole sheets obtained from one slab can be from 4 to 21 sheets.

At the same time, when choosing the multiplicity of sheets - the whole number of sheets, which can be obtained by dividing one roll (slab), it is necessary to take into account the technological limitation on the rolling table of the mill, according to which the length of the roll cannot exceed 52,000 mm. Based on this limitation and the length of the ordered sheets, the multiplicity along the length of the roll cannot exceed 8 (8 × 6000 = 48000 <52000 mm).

At the same time, the possibility that in this case it is possible to cut the roll lengthwise, since the width of the ordered sheet is 1500 mm and the working length of the roll barrel is 4800 mm, should be taken into account. That is, the width multiplicity can be 2.

For a batch of 44 sheets, a multiplicity of 2 × 2, 4 × 1 will be possible, where the first digit shows the possible number of sheets in the roll in the longitudinal direction, and the second in the transverse. For a batch of 45 sheets, a multiplicity of 5 × 1 will be possible. For a batch consisting of 46 and 47 sheets, not a single multiplicity is possible. For a batch of 48 sheets, a multiplicity of 2 × 2, 3 × 2, 4 × 1, 4 × 2, 6 × 1, 6 × 2, 8 × 1, 8 × 2 will be possible.

For each of these multiplicities, the weight of the slab is determined at a nominal value of the expenditure coefficient equal to 1.087. The obtained values are analyzed on the condition of the permissible load capacity of the cranes (<30 t), and the slab sizes corresponding to these values are analyzed on the conditions of the limited design of the heating furnace and rotary tables of length (<4800 mm) taking into account the available sections of the molds of the continuous casting machine.

The multiplicity of cutting 8 × 2 sheets does not exceed the number of sheets in excess of the required in the batch (48 sheets = 3 rolls, cut into 8 sheets along and 2 sheets across) and is the maximum possible subject to all the above restrictions. Accordingly, it meets the conditions for maximum productivity of the rolling process.

For this case, the optimal mass of the slab will be 24.575 tons.

The sections of the molds of the continuous casting machine in this particular case are possible combinations of thicknesses 190, 250, 300 mm and widths 1400, 1560, 1650, 1730, 1850, 2030, 2300, 2520, 2700 mm. Since the length of the slab should not be less than 2500 and more than 4800 mm (restriction imposed by the design of the furnace), such a cross section is selected that provides the required mass of the slab under the conditions along its length. The calculation shows that these can be slabs with sizes of 300 × 2700 × 3880, 300 × 2520 × 4120, 300 × 2300 × 4560 and 250 × 2700 × 4660 mm. Based on the conditions for ensuring maximum productivity, minimizing trimmings and, as a result, the real consumption coefficient, a slab of the largest cross section (300 × 2700 × 3845 mm) is selected if a crystallizer of any of the other sizes is not installed by the time of rolling this batch. Since its replacement is a labor and materially expensive process.

Example 4. An order was received for the production of a batch of sheets with a total weight of 50 tons and a sheet size of 21 × 2000 × 12000 mm. Based on the geometric dimensions and specific gravity of the metal, we determine the mass of the sheet, which in this case will be 3.956 tons. Given the tolerance on the order value of ± 5%, the weight of the finished product can vary from 47.5 to 52.5 tons. Based on the weight of the sheets , the batch weight, taking into account the need to obtain only an integer number of sheets, can be only 51.428 tons. And accordingly, the number of sheets in the batch will be 13 pcs.

Based on the existing restrictions on the mass of the slab, which is 5.2 t for a slab of a minimum size of 190 × 1400 × 2500 mm, and 30.4 t for a slab of a maximum size of 300 × 2700 × 4800 mm, and taking into account the crane lifting capacity of 30 t the number of whole sheets obtained from one slab can be from 2 to 7 sheets.

At the same time, when choosing the multiplicity of sheets - the whole number of sheets, which can be obtained by dividing one roll (slab), it is necessary to take into account the technological limitation on the rolling table of the mill, according to which the length of the roll cannot exceed 52,000 mm. Based on this restriction and the length of the ordered sheets, the multiplicity along the length of the roll cannot exceed 4 (4 × 12000 = 48000 <52000 mm).

At the same time, the possibility should be taken into account that in this case it is possible to cut the roll lengthwise, since the width of the ordered sheet is 2000 mm and the working length of the roll barrel is 4800 mm. That is, the width multiplicity can be 2.

For a batch of 13 sheets, not a single multiplicity is possible. It is not possible to produce one sheet from one slab, since the weight of one sheet (3.956 tons) is less than the minimum allowable weight of the slab (5.2 tons). Accordingly, it will not be possible to complete the order without exceeding the number of sheets in the batch of the specified volume.

For a batch of 14 sheets, a multiplicity of 1 × 2, 2 × 1 will be possible, where the first digit shows the possible number of sheets in the roll in the longitudinal direction, and the second in the transverse. For a batch of 15 sheets, a multiplicity of 3 × 1 will be possible. For a batch of 16 sheets, a multiplicity of 1 × 2, 2 × 1, 2 × 2, 4 × 1 will be possible.

For each of these multiplicities, the weight of the slab is determined at a nominal value of the expenditure coefficient equal to 1.087. The obtained values are analyzed on the condition of the permissible load capacity of the cranes (<30 t), and the slab sizes corresponding to these values are analyzed on the conditions of the limited design of the heating furnace and rotary tables of length (<4800 mm) taking into account the available sections of the molds of the continuous casting machine.

If the finished product warehouse allows you to store a certain amount of measured products in excess of the required quantity until it is sold, then it will be optimal to choose a cutting ratio of 2 × 2 (16 sheets = 4 rolls, cut into 2 sheets along and 2 sheets across) and is the maximum possible, subject to of all these restrictions and meets the conditions for maximum productivity of the rolling process and a minimum expenditure coefficient, although 3 sheets gives an excess of the number of sheets over the required in the party.

For this case, the optimal mass of the slab will be 17.2 tons.

The option with 15 sheets per batch and exceeding the production of the required number of sheets per batch by 2 sheets of the specified size has the only possible cutting ratio of 3 × 1 (15 sheets = 5 peals cut into 3 sheets lengthwise). In this case, the mass of the slab will be 12.9 tons. However, this option is not optimal either in terms of the expenditure coefficient or in the productivity of the process, due to the lack of longitudinal cutting of the sheet.

If the minimum excess of the quantity of measured products over the required one is a priority task to the detriment of productivity and minimization of the expenditure coefficient, as, for example, in our case, then for a batch of 14 sheets, a cutting ratio of 1 × 2 sheets is selected, which corresponds to shorter machine time rolling in comparison with a multiplicity of 2 × 1. Therefore, you should choose a slab with a mass that allows you to get a peal that satisfies this condition. In this case, the real mass of the slab should take into account the expenditure coefficient, including the loss of metal due to technological cutting, sampling and burning.

For this case, the optimal mass of the slab will be 8.6 tons.

The sections of the molds of the continuous casting machine in this particular case are possible combinations of thicknesses 190, 250, 300 mm and widths 1400, 1560, 1650, 1730, 1850, 2030, 2300, 2520, 2700 mm. Since the length of the slab should not be less than 2500 and more than 4800 mm (the restriction imposed by the design of the furnace), such a cross section is selected that provides the required mass of the slab under the conditions along its length. The calculation shows that these can be slabs of many sizes. Based on the conditions for ensuring maximum productivity, minimizing trimmings and, as a consequence, the real consumption coefficient, in this case, the multiplicity is chosen slab preferably with a larger width, for example 250 × 1730 × 2540, 190 × 1850 × 3130 mm. Under real production conditions, a slab of the available standard size or standard size of the mold installed at the time of rolling this batch will be selected.

Claims (1)

A method of manufacturing batches of hot-rolled sheets with minimal waste when cutting roll, including obtaining slabs on continuous casting machines (CCM), heating, rolling and cutting the resulting roll on sheets of predetermined sizes, while taking into account the set batch weight within the tolerance P-ΔP ₁ ... P + ΔP ₂ , where ΔP ₁ and ΔP ₂ are the negative and positive tolerances on the weight of the batch, pre-determine the weight of one sheet P ₁ and the corresponding possible number of sheets n in the batch, equal to n = (P-ΔP ₁ ) / P ₁ ... (P + ΔP ₂ ) / P ₁ , then for each integer th n determine the cutting ratio K _i = K ₁ · K ₂ , where K _i is the number of sheets obtained by cutting the roll produced from the slab obtained at the continuous casting machine, taking into account the standard sizes of slabs, K ₁ is the allowable number of sheets when cutting the roll in the transverse direction, and K ₂ is the permissible number of sheets when cutting the roll in the longitudinal direction, for each of the obtained values of K _i determine, based on the conditions of the possible lifting capacity of the cranes, the permissible slab weight P of the _{slab i} = k _pacx · K _i · P ₁ , where k _paxх = 1,011 ... 1,274 - expense coefficient taking into account technological losses metal, and then subject to the condition of minimum consumption coefficient value and a minimum amount of excess dimensional sheets over a desired number of the party, with account of technological limitations of the equipment define the maximum cutting peal multiplicity K _i = K _max and satisfying these conditions determine the optimal weight slab P = _opt.slyaba k _pacx · K _max · P ₁ , and the slabs are obtained on a continuous casting machine, which is equipped with a mold, the cross-sectional dimensions of which correspond to the condition for obtaining slabs with an optimal weight equal to P _{o fr slab} .