SU833333A1 - Method of producing hot rolled thick sheets - Google Patents

Description

The invention relates to rolling production and can be used in the production of thick sheets in the line of a hot rolling mill with a reversing finishing stand.

A known method for the production of thick sheets, which consists in heating slabs for rolling in methodological furnaces, followed by rolling in a rough and finishing reversing stands

A disadvantage of this method is the poor quality of the sheets due to longitudinal grow and unevenness of the mechanical properties along the length of sheets ₁₅ vyz- Bathing different cooling conditions during rolling the front and rear ends of roll, this temperature difference of the front and rear ends of the rolls leads' to a temperature wedge along the length of roll ; jo which due to various conditions of deformation leads to uneven formation of the geometry of the finished product and mechanical properties.

A known method of rolling thick sheets, in which to eliminate the noted drawbacks, regulate the temperature field along the length of the peals, aimed at reducing the temperature wedge by installing heating means in the mill line, for example, heat-reflecting screens f2].

The disadvantages of this method include the inertia of the system, which leads to an increase in the machine rolling time, which is additionally delayed by aligning the temperature wedge and metal intensity of the equipment for implementing this method.

The purpose of the invention is to improve the quality of the sheets by reducing the longitudinal heterogeneity and alignment of mechanical properties.

This goal is achieved by the fact that in the method of hot rolling of thick sheets, including the preparation of slabs, their heating and rolling in a reversing finishing stand, before crimping the roll z 833333 in the last pass along the length, it creates an inverse temperature wedge equal to the temperature drop along the length of the roll during rolling it in the last pass, by changing the speed of rolling- ' _s ki and compression in one or more passes in accordance with the equation

Ni νζ- n / h ₂ (N _g nJ Vj / ^d 4 ^b 4 / ^q g _ Od \ + W ° M

IH ₄ v ₄ \ h ^ H ₄ Hj '

-d / b + 273] 4 'where α.χ18,2 · 10 (is the relative heat radiation before the ί -th passage, ° C, mm / s;

is the metal temperature before the ίth passage, ^u C; jo

L '- the length of the roll after the ιth passage, m;

V. - rolling speed in the i-th passage, m / s;

Щ - thickness of the roll before 25 i-th passage, mm.

In this case, a temperature wedge is created in the last three to four passes. l -1, ¾ 3 .... - p is the number of the passage in the course of rolling. thirty

The essence of the proposed method lies in the fact that during reverse hot rolling of the sheets in the finishing stand after each pass, a temperature wedge is formed along the length of the roll, the value of ko. 35 of which is directly proportional to the temperature of the metal to the fourth degree, the rolling time in this pass and inversely proportional to the thickness of the roll.

Due to the fact that when rolling ^thick-A tire peal at the outlet of the stand is always less than the magnitude at the input of the absolute compression in the passage, the cooling during rolling of roll sections located after the stand will 'move more intensively, than sections of peals located before the crate. Therefore, the choice of the magnitude of machine time or, similarly, the rolling speed of the roll through the aisles can be affected. add to the value of the temperature wedge. In order to ensure a constant rolling temperature along the length of the roll in the last pass, it is necessary to create a return temperature wedge ~ this value, which will be compensated by cooling the tail sections of the roll during movement during rolling in the last pass. This condition can be fulfilled by reducing the rolling speed in odd passes, except for the last and / or increasing the rolling speed in even and last passes and redistributing the compression of the roll along the passes: increasing compression in odd and decreasing in even passes in accordance with the equation .. B In this equation, the right component is the temperature drop along the length of the tail sections of the roll when it moves during rolling in the last pass.

Temperature-deformation and high-speed modes of rolling the roll with dimensions of 10x20000x30000 mm for the conditions of the plate mill 3600 are presented in the table. In the embodiment modes 1 shows the calculated in accordance with the technology of the mill at a constant rolling speed through passages equal to 3.4 m / s, As a result of rolling over the length of roll at the time of its passage through the roll gap formed _{on the} wedge zuegsya temperature equal 36 S.

In order to eliminate the temperature wedge, the level calculated the speed and temperature-deformation modes of rolling in the aisles (options II, III, lV) According to option II, the rolling speed in 3 passes was reduced from 3.4 to 0.7 m / s, in other passes the speed remained unchanged. As a result of a decrease in the rolling speed in 3 passes, a temperature wedge is created equal to +70 ° C. In 4 · passes, in this case, a reverse temperature wedge of -51С is formed, which is fully compensated due to the cooling of the tail sections of the roll along its length during its movement during rolling in 5 aisle. In the third embodiment, a rolling mode is presented with a simultaneous decrease in speed in 3 passes from 3.4 to 1/0 m / s and an increase in 4 and 5 passes from 3.4 to a maximum of 5.8 m / s. In this case, to obtain a constant temperature of the end of rolling along the length of the roll, it is necessary to create a smaller temperature wedge after 3 passes (+50. C) compared to mode II (+70 C). The embodiment presents a combined deformation-speed rolling mode with a simultaneous decrease in rolling speed in 3 passes to 1.34 m / s,. an increase in the rolling speed in 4 and 5 passes to 5.8 m / s and a decrease from 5 833333 6 wearable compression in 4 passes with

27.1 to 17.9% due to redistribution of compression in 4 and 5 passes. This mode allows you to get a constant temperature of the end of rolling along the length of ₅ rolls with a minimum value of the temperature wedge after 3 passes (+ 4СГС) and practically without changing the rolling cycle.

The use of the proposed method c) for the manufacture of thick sheets in comparison with the known one provides the simplicity of implementation on the existing hot plate reversible hot rolling mills; operational and practically inertialess regulation of the longitudinal temperature wedge during the rolling process, 'high regulation efficiency. In addition, when using the proposed method does not require additional installation of expensive equipment that complicates the process.

Option Pro- move Roll thickness, mm, N Relative compression E% Speed — rolling speed, V, m / s The temperature of the roll at the time of passage of the deformation zone, b ° C Temperature wedge DF = tr-txi ° C Total aisles, machine rolling time, s before the passage after the passage head section, 6 tail section ^b 1 1 45 32 28.9 3.4 1095 1092 -3 2 32 21 34,4 3.4 1078 1085 -7 3 21 14 33.3 3.4 1062 1045 + 17 29.3 • 4 ¹⁴ 10.2 27.1 3.4 992 1020 -28 5 10,2 9.8 3.9 3.4 970 934 +36 II 1 45 32 28.9 S · ⁴ 1095 1092 +3 2 32 21 34,4 3.4 1078 1085 -7 3 21 14 33.3 0.7 1062 992 +70 53,2 4 14 10.2 27.1 3.4 908 959 -51 5 10,2 9.8 3.9 3.4 890 890 0 III 1 45 32 28.9 3.4 1095 1092 +3 2 32 21 34,4 3.4 1078 1085 -7 3 21 14 33.3 1,0 1062 1012 +50 37.5 4 14 10,2 27.1 5.8 949 980 -31 . 5 10,2 .9.8 3.9 5.8 930 930 0 ΙΊ 1 45 32 28.9 3.4 1095 1092 +3 2 32 21 34,4 3.4 1078 1085 -7 3 21. 14 33.3 1.34 1062 1022 +40 32,2 4 14 11.5 17.9 5.8 959 990 -31 5 1 1., 5 9.8 15.8 5.8 940 940 ABOUT

Ί

Claims (1)

(54) METHOD OF MANUFACTURE OF FIREDEDIES; THICK SHEETS in the last pass along its length create a return temperature pin, equal to the temperature of the roll along the roll when it is rolled in the last pass, by changing the speed of the piercing and reduction in one or several passes in accordance with equation 1 (U-k3 ag Lg Vi С H, / V u - / - + I Hj V4 VH d., - relative heat radiation before the 1st pass ° С, mm / s; -t - metal temperature before the 1st pass Ij - roll length after the pass , m; - rolling speed in i pass, m / s; H - thickness of the roll before the 1st pass, mm. At this rate Aturny.klin create in the last three - four passes. -1,2; 3 .... - n - number of the passage in the course of rolling. The essence of the proposed method lies in the fact that during the reversive hot rolling of sheets in the finishing stand after each a temperature click is formed along the length of the roll, the value of which is directly proportional to the temperature of the metal in the fourth degree, the rolling time in the passage and inversely proportional to the thickness of the roll. Due to the fact that during rolling the thickness of the roll at the exit from the cage is always less than at the entrance by the amount of absolute reduction in this passage, cooling during the rolling of the sections of the roll after the cage will go more intensively than sections of the race, which is up to the stand. Consequently, the choice of the magnitude of this time or, which is similar, the speed of rolling the roll through the aisles can affect the value of the temperature wedge. In order to ensure a constant rolling temperature along the length of the roll in the last pass, it is necessary to create a reverse temperature wedge of such magnitude in front of this pass that will compensate for by cooling the tail sections of the roll when it moves during the rolling in the last flight. This condition can be accomplished by reducing the rolling speed in odd passes except the last and / or increasing the rolling speed in even and last passes and redistributing the roll rolling down the passes: increasing the rolling in odd passes and decreasing in even passes in accordance with the equation .. In this equation, the right component is the temperature drop along the length of the tail sections of the roll when it moves during rolling in the last pass. The temperature-deformation and high-speed modes of rolling of the roll with dimensions of 1Ox2OOOOHZOOOO mm for the conditions of the plate mill 3600 are presented in the table. In option I, the design modes are given in accordance with the technology adopted at the mill at a constant rolling speed along the aisles equal to 3.4 m / s. As a result of such rolling along the length of the roll, a temperature wedge of 36 C is formed at the time of its passage through the deformation zone. In order to eliminate the temperature wedge through the level, the speed and temperature-deformation modes of rolling along the aisles are calculated the rolling speed in the 3rd pass was reduced from 3.4 to 0.7 m / s, in the remaining passes the speed remained unchanged. As a result of reducing the rolling speed in 3 passes, a temperature wedge of +70 C is created. In 4 passes, in this case, a reverse temperature wedge of -51C is formed, which is fully compensated for by cooling the tail sections of the roll in length as it moves. 5 pass. In the third variant, the rolling mode is presented with a simultaneous decrease in speed in 3 passes from 3.4 to I / O m / s and increasing it in 4 and 5 passes from 3.4 to a maximum of 5.8 m / s. In this case, to obtain a constant temperature for the end of rolling along the length of the roll, it is necessary to create a smaller temperature wedge after 3 passes (+50 ° C) compared to mode I (+70 ° C). The variant presents a combined deformation-speed rolling mode with a simultaneous decrease in the rolling speed in 3 passes to 1.34 m / s. by increasing the rolling speed in 4 and 5 passes to 5.8 m / s and reducing the relative reduction in 4 passes from 27.1 to 17.9% due to the redistribution of reduction in 4 and 5 passes. This mode allows to obtain a constant temperature of the end of rolling along the length of the stock at the minimum value of the temperature wedge after 3 passes (+ 4Cg C) and practically without changing the rolling cycle. The use of the proposed method for the manufacture of thick sheets in terms of stevne36 NPA with a known one provides ease of implementation on existing thick plate reversing mills for hot rolling; efficient and practically inertialess regulation of the longitudinal temperature wedge in the rolling process, high efficiency of the regulling. In addition, when using offers, no additional installation of expensive equipment is required, which complicates the process. 78 The invention method of production, hot rolled thick sheets, mainly in the line of hot rolling mill with reversing finishing stand, including temperature control along the length of peals, crimping peals in odd and even passages and crimping in the last pass to gchetovy size, different that, in order to improve the quality of the sheets by reducing the longitudinal thickness variation and improving the mechanical properties, on the peals before the last pass create a temperature wedge equal to the temperature drop along the length of rolls when they are crimped in the last pass and directed against the rolling stroke by lowering the rolling speed in odd passes and increasing the rolling speed in even and last passes with a corresponding increase in roll reductions in passages with reduced rolling speeds and decreasing reductions in passes by increased rolling speeds, defined by © according to the equation J: i ±. (± b. / 1 b. a-1 LV, Ua i ViU lv ./CH tJ / bV I l I -. ,, I - l 1 -. . Vn .Hn 8 / t -J-273 4, 2-lO 1 on / abundant heat radiation before -7 - .. YN passage for I mm of the thickness of the bar for 1 s GS mm / s); fc is the temperature of the metal before the i -th pass J; the length of the roll after the i-th passage, m; Vf - rolling speed in the i-th pass, m / s; H is the thickness of the peal before the i-th passage, mm, 1,2, ..., 3 ... h is the number of the passage along the way about the method according to p. I, that is, that temperature is given in after dnyus three or four ah. Sources of H11 formation, taken into account when Safte MM expats, are rolling on continuous and semicontinuous. Metallurgizdat, 1962, 2-2O4. Copyright certificate of the USSR 1998, cl. B 21 B 37 / GS, 1976.