SU969435A1

SU969435A1 - Method for cooling shaped cast iron billets in continuous casting process

Info

Publication number: SU969435A1
Application number: SU802974576A
Authority: SU
Inventors: Виктор Алексеевич Ефимов; Виктор Кириллович Ханин; Илья Исакович Быков; Владимир Сергеевич Шумихин; Виталий Иванович Московка; Владимир Николаевич Бабич; Иван Григорьевич Раздобарин; Виктор Иванович Грищенко
Original assignee: Институт проблем литья АН УССР; Завод "Центролит"
Priority date: 1980-06-18
Filing date: 1980-06-18
Publication date: 1982-10-30

Description

Изобретение относится к метал-* лургии, конкретнее - к управлению процессом разливки металла в горизонтальных машинах непрерывного литья чугуна.The invention relates to metallurgy *, and more particularly, to controlling the process of casting metal in horizontal continuous casting machines.

Известен способ управления режимом затвердевания непрерывнолитой заготовки, в котором слиток вытягивают со скоростью 0,2-2 мм/с, охлаждая его в кристаллизаторе^с интенсивностью 1000-2000 Вт/м.град[(].A known method of controlling the solidification regime of a continuously cast billet, in which the ingot is pulled at a speed of 0.2-2 mm / s, cooling it in a mold with an intensity of 1000-2000 W / m grad [(].

Известен также способ получения полых чугунных заготовок, в котором охлаждение наружной поверхности отливки в кристаллизаторе производится с интенсивностью 3500-4000 Вт/м.град, а внутренней - 2500*3000 Вт/м·град£2].There is also known a method for producing hollow cast iron billets, in which the cooling of the outer surface of the casting in the mold is carried out with an intensity of 3500-4000 W / m grad, and the inner 2500 * 3000 W / m · deg £ 2].

Наиболее близким к предлагаемому является способ автоматического управления режимом работы кристаллизатора установки непрерывной разливки металлов, заключающийся в тож, что изменяют конусность в зависимости от скорости разливки и температуры разливки, по которому дополнительно измеряют температуру поверхности слитка и при отклонении этой температуры от заданного значения соответствую^s щей скорости устойчивой разливки изменяют конусность кристаллизатора в направлении восстановления заданной температуры поверхностного слоя на выходе из кристаллизатора [З].The closest to the proposed is a method for the automatic control mode of operation of the mold of the continuous casting of metals, comprising the identity, that alter the conicity, depending on the casting speed and casting temperature by further comprising measuring the temperature of the ingot surface and at a deviation of this temperature from the set value corresponding to ^s boiling steady casting speeds change the taper of the mold in the direction of restoring a given temperature of the surface layer to During the crystallizer [W].

Существенным недостатком известного способа является невозможность обеспечения теплового режима кристаллизатора при получении слитка фа15 сонного профиля, особенно при непрерывном литье заготовок с развитой разностенной поверхностью. При поддержании температуры на заданном уровне для всей разностенной поверх²⁰ ности одинаковой и равной Т^_Од₍в участках профиля с утоньшенным сечением, например ребра, получают отливку с отбелом чугуна недопустимой величины. При этом качество отливаемой заготовки ухудшается вследствие получения неоднородной структуры металла вдоль профиля с развитой поверхностью. Таким образом, известный 5 способ управления тепловым режимом кристаллизатора изменением конусности пригоден только для литья слитков и заготовок одного профиля без развитой поверхности. При этом номенкла-ю тура отливаемых изделий существенно сужается.A significant disadvantage of this method is the inability to ensure the thermal regime of the mold upon receipt of the ingot of the face profile, especially during continuous casting of workpieces with a developed differential surface. While maintaining the temperature at a given level for the entire delimited surface ²⁰ equal and equal to T ^ _О d ₍ in sections of the profile with a thinned cross-section, for example, ribs, a casting with bleaching of cast iron of an unacceptable value is obtained. Moreover, the quality of the cast billet deteriorates due to the inhomogeneous metal structure along profile with a developed surface. Thus, the known method 5 for controlling the thermal regime of the mold by changing the taper is suitable only for casting ingots and billets of the same profile without developing of the surface. In this case nomenkla th round of the cast product is narrowed considerably.

Цель изобретения - расширение номенклатуры литых заготовок, получаемых непрерывным способом, за счет 15 включения изделий с развитой разностенностью и повышение качества отливок.The purpose of the invention is the expansion of the range of cast billets obtained in a continuous way, due to the 15 inclusion of products with developed difference and improving the quality of castings.

Поставленная цель достигается тем, что в способе, включающем различный теплоотвод от различных участков заготовки, изменяют интенсивность теплоотвода по периметру^заготовки в пределах 25О-ЮОО Вт/м град от тонко- & стенных частей и 1500-2500 Вт/мЯград от толстостенных.This goal is achieved by the fact that in a method that includes different heat sinks from different sections of the workpiece, the intensity of heat removal along the perimeter of the workpiece is changed within 25 ° -10 ° W / m grad from thin-walled parts and 1500-2500 W / m Grad from thick-walled.

На фиг. 1 показан графитовый кристаллизатор для отливки станочной направляющей, сечение; на фиг. 2 - то же, для отливки заготовки со сложным ³⁰профилем.In FIG. 1 shows a graphite mold for casting a machine guide, section; in FIG. 2 - the same for casting a workpiece with a complex ³⁰ profile.

Кристаллизатор 1 содержит охлаждающие секции 2 для охлаждения заготовки 3 с развитой разностенностью. В этом случае скорость затвердева- ³⁵ния тонких частей заготовки уменьшают до,0,4-0,5 мм/с за счет снижения интенсивности теплообмена до 400 500 Βτ/μ^ϊ град путем уменьшения потока охладителя через охлаждающую . ⁴⁰ секцию 2. Контроль интенсивности охлаждения в заданных пределах производят по показаниям термопар, горячие спаи которых установлены в характерных зонах графитового кристал- ⁴⁵лизатора. При этом, в зонах, соответствующих тонкостенным участкам заготовки, температуру увеличивают с 45О-55О до б50-750°С, а толстостенным - снижают с 95Ο-ΙΟ5Ο до 750- 50The mold 1 contains cooling sections 2 for cooling the workpiece 3 with a developed difference. In this case, the hardening rate of ³⁵ thin parts of the preform is reduced to 0.4-0.5 mm / s by reducing the heat transfer rate to 400 500 Βτ / μ ^ д deg by reducing the flow of coolant through the cooling. 2. The control section ⁴⁰ Cooling intensity within a predetermined range of indications produce thermocouple hot junctions are installed in characteristic zones of the graphite crystal ⁴⁵ catalysts. Moreover, in areas corresponding to thin-walled sections of the workpiece, the temperature is increased from 45O-55O to b50-750 ° C, and thick-walled - reduced from 95Ο-ΙΟ5Ο to 750-50

850°С.850 ° C.

Таким образом, изменяя интенсивность теплоотвода путем дифференцированного охлаждения, достигают изменения интенсивности теплоотвода в 55 пределах от 2500 до 250 Вт/м²-· град в зависимости от профиля и величины разностенности заготовки.Thus, by changing the heat sink intensity by means of differentiated cooling, a change in the heat sink intensity is achieved in 55 ranges from 2500 to 250 W / m ² - · deg, depending on the profile and the difference in the size of the workpiece.

При управлении тепловым режимом по известному способу температура частей графитового кристаллизатора, соответствующих толстостенным и тонкостенным участкам заготовки, практически не регулируется, так как теплоотвод производится с одинаковой интенсивностью от всей поверхности заготовки. В результате тонкие части переохлаждаются с образованием отбеленного” слоя. В то же время толстостенные части профильной заготовки затвердевают значительно медленнее, с образованием ферритоперлитной структуры. чугуна.When controlling the thermal regime according to the known method, the temperature of the parts of the graphite mold corresponding to thick-walled and thin-walled sections of the preform is practically not regulated, since the heat is removed with the same intensity from the entire surface of the preform. As a result, the thin parts are supercooled to form a bleached ”layer. At the same time, the thick-walled parts of the profile blank harden much more slowly, with the formation of a ferritic perlite structure. cast iron.

Таким образом, получается неоднородное строение литого материала различных частей заготовки, что существенно снижает ее качество.Thus, the heterogeneous structure of the cast material of various parts of the workpiece is obtained, which significantly reduces its quality.

Предлагаемый способ реализуется на примере управления тепловым режимом кристаллизатора с графитовой втулкой для вытягивания заготовки КС0451-430В со сложным профилем. Габариты заготовки: CL = 100 мм; ? = = 20-22 мм; Е= 270 мм (фиг. 2)..The proposed method is implemented by the example of controlling the thermal regime of a mold with a graphite sleeve for drawing a blank КС0451-430В with a complex profile. Dimensions of the workpiece: CL = 100 mm; ? = = 20-22 mm; E = 270 mm (Fig. 2) ..

В процессе вытягивания температуру чугуна в металлоприемнике поддерживают на уровне 1350 С. Скорость вытягивания заготовки - 0,30 м/мин. При этом интенсивность охлаждения графитовой втулки в местах, соответствующих тонкостенным частям заготовки, составляет не более 300 Вт/м-град, а в толстостенных частях -1500 Вт/м* •град. В результате применения такой интенсивности охлаждения средняя скорость затвердевания металла в кристаллизаторе составляет около 0,45 мм/с.In the process of drawing, the temperature of the cast iron in the metal receiver is maintained at 1350 C. The speed of drawing the workpiece is 0.30 m / min. In this case, the cooling rate of the graphite sleeve in places corresponding to thin-walled parts of the workpiece is not more than 300 W / m-deg, and in thick-walled parts –1500 W / m * • deg. As a result of applying this cooling intensity, the average solidification rate of the metal in the mold is about 0.45 mm / s.

Анализ полученного литого материала заготовки показывает, что толщина дефектной зоны составляет всего 23 мм, в то время как ранее она достигала 6-7 мм. Практически устранен отбел и получена однородная структура чугуна по сечению отливки. При этом количество перлита в поверхностной зоне 95“9б%. Форма включений графита - Гф 2; Гф 4. Твердость литого материала составляет 190-200 НВ.Analysis of the obtained cast material of the billet shows that the thickness of the defective zone is only 23 mm, while previously it reached 6-7 mm. The bleaching was practically eliminated and a uniform structure of cast iron was obtained over the cross section of the casting. Moreover, the amount of perlite in the surface zone is 95 “9b%. The form of graphite inclusions - GF 2; Gf 4. The hardness of the cast material is 190-200 HB.

I -I -

Claims

(5) METHOD FOR COOLING THE CAST IRON PREPARATIONS OF THE SHAPE PROFILE UNDER THE CONTINUOUS The invention relates to metallurgy, more specifically to controlling the process of pouring metal in horizontal continuous casting machines. A known method of controlling the solidification mode of a continuously cast billet, in which the ingot is pulled at a speed of 0.2-2 mm / s, is cooled in a crystallizer with an intensity of 1000-2000 W / m.grad. There is also known a method for producing hollow cast iron billets, in which the cooling of the outer surface of the casting in the mold is performed with an intensity of 3500-4000 W / m.h. and internal - 2500-3000 W / Mrad 2 The closest to the proposed method is automatic control of the mode of operation of the crystallizer. TOW continuous casting plants, which change the taper and depending on the CASTING of the casting speed and the casting temperature, by which the surface temperature of the ingot is additionally measured and at By changing this temperature, the conicity of the crystallizer changes in the direction of restoring the predetermined temperature of the surface layer at the outlet of the crystallizer from a given value of the stable casting method. A significant disadvantage of the known method is the impossibility of ensuring the thermal mode of the mold when producing a shaped profile ingot, especially with continuous casting developed differential surface. By maintaining the temperature at a given level for the entire differential surface of the same and equal sections of the profile with a thinned cross section, such as ribs, a casting of cast iron with an unacceptable value of 39 is obtained. At the same time, the quality of the cast billet is deteriorated due to the formation of a non-uniform metal structure along a profile with a developed surface. Thus, the known method of controlling the thermal mode of the mold by changing the taper is only suitable for casting ingots and billets of one profile without a developed surface. At the same time, the range of products to be molded is significantly narrowed. The purpose of the invention is to expand the range of cast billets produced in a continuous way by incorporating products with developed wall thickness and improving the quality of castings. The goal is achieved by changing the heat removal rate around the billet in a method involving different heat removal from different parts of the workpiece. within 250-1000 W / m grad from thin-walled parts and 1500-2500 W / m. hail from thick-walled. FIG. Figure 1 shows a graphite crystal for a machine tool for guiding, section; FIG. 2 is the same for casting a billet with a south-profile. The mold 1 contains cooling sections 2 for cooling the workpiece 3 with a well-developed variuos ratio. In this case, the rate of solidification of thin parts of the workpiece is reduced to, O, -0.5 mm / s by reducing the heat exchange rate to 400,300 degrees by decreasing the coolant flow through the cooling. section

2. Monitoring the intensity of cooling within the prescribed limits is carried out by the indications of thermocouples, the hot junctions of which are installed in the characteristic areas of the graphite crystallizer. At the same time, in the zones corresponding to thin-walled areas for cooking, the temperature is increased from k5Q-5SQ to 650-750 ° C, and the thick-walled one is reduced from 950-1050 to 750850 ° C. Thus, by varying the intensity of the heat sink by differentiated cooling, one achieves a change in the intensity of the heat sink in the range from 2500 to 250 W / m-hail depending on the profile and the difference in the thickness of the workpiece. 5 When controlling the thermal regime in a manner known per se, the temperature of the portions of the graphite crystallizer corresponding to the thick-walled and thin-walled parts of the workpiece is practically unregulated, since the heat sink is produced with the same intensity from the entire surface of the stock. As a result, the thin parts are supercooled to form a bleached layer. At the same time, the thick-walled parts of the profile billet harden much more slowly, with the formation of ferritic perlite structure, cast iron. Thus, a non-uniform structure of the cast material of various parts of the workpiece is obtained, which significantly reduces its quality. The proposed method is implemented on the example of controlling the thermal regime of a mold with a graphite sleeve for pulling the KCOt51 30B billet with a complex profile. Workpiece dimensions: CL 100 mm; f 20-22 mm; 6 270 mm (Fig. 2). During the drawing process, the temperature of the cast iron in the metal receiver is maintained at 1350 C. The drawing speed of the billet is 0.30 m / min. At the same time, the cooling rate of the graphite bushing in the places corresponding to the thin-walled parts of the procurers is no more than 300 W / m-deg, and in the thick-walled parts of x-1500 W / m the degree. As a result of using such a cooling intensity, the average solidification rate of the metal in the crystallizer is about 0.5 mm / s. Analysis of the obtained cast material of the workpiece shows that the thickness of the defective zone is only 23 mm, while it previously reached 6-7 mm. Chisels are practically eliminated and a uniform structure of cast iron over the casting section is obtained. The amount of perlite in the surface area. The form of graphite inclusions - GF 2; Gf 4. The hardness of the cast material is 190-200 HB. Claims The method of cooling cast iron billet shaped profile with continuous casting, including a different heat removal from different parts of the workpiece, characterized in that, in order to expand the nomenclature

5363 35

cast billets and increase their ka-1. Copyright

qualities change the intensity of the heat-no. 536007, cl. AT

removal around the perimeter of the workpiece in pre-. 2. Rams Oh,

affairs 250-1000 W / m g hail from fine-cast iron. M,

wall parts and 1500-2500 BT / M frpaA5 1968, p. 89-90. from thick-walled.

Information sources,.

3. Copyright

taken into account in the examination i | ° 628991, cl. AT

USSR certificate 22 D 11/00, 1976. A. et al. Continuous, Metallurgizdat,

USSR certificate 22 D 11/16, 1978.

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