UA31820U - Continuous casting mold - Google Patents

Abstract

A continuous casting mold contains two narrow walls with copper layer fastened to the steel housing by fastening pins and steel clad layer located from the back side, a water cooling system formed by channels. In the mold throughout entire width and length of narrow walls channels are made in the crosscut of rectangular form, the cavity of each of which throughout entire depth is located both in the part of steel plate and in the part of base metal from copper. The surface of the steel plate is equipped with the extensions rigidly connected to its surface, for example, by welding. Extensions are made with vertically distributed threaded openings for fastening pins.

Description

Description of the invention

A useful model, continuous metal casting crystallizer, belongs to the metallurgy of ferrous and 2 non-ferrous metals, in particular to continuous metal casting.

Crystallizers of a composite design are known for the removal of heat from molten metal, in which narrow walls of copper alloys containing water cooling channels of rectangular cross-section are located between wide ones and fixed to the steel body with the help of fastening pins. At the same time, the entire working surface of the narrow walls is included in the cavity of the crystallizer, so the basic parameters of continuous casting of blanks, such as the pouring speed and its quality, largely depend on the state of their heat exchange.

In known crystallizers, the narrow walls are made of a removable design, in which the places for fastening the pins in the copper wall, which contains rectangular (milled) channels, for connecting it to the steel body are located between the two channels closest to the side faces (ribs), and near the insulating spacers are located on the ribs.

A significant disadvantage of this crystallizer is that for the specified places, areas of increased size are needed, both in thickness and in width, as a result of which the water cooling channels close to the ribs must be made at a remote distance from them.

For example, in known crystallizers of this design, the dimensions of these sections along the width of the wall from the edge to the nearest two channels and between them are made most often in the intervals of 22-24 and 24-3 mm, respectively, while the distance between other channels along the width of the wall is 10- 13 mm.

The known data of the company "Uralmash - MO" is that due to the presence of areas of increased size near the ribs and between the near channels, there is a problem with the organization of cooling of the specified zones of the working surface of narrow walls. At the same time, it was established that the heating temperature of these zones (Tr) during the operation of the crystallizers exceeds the temperature of the middle of the working surface (Ts) of the wall by more than 502. However, 29 with an unsatisfactory organization of cooling the edges of the wall by nearby channels, their overheating occurs by 1100-2002 shsh (11 .

I1) L.V. Bulanov, L.G. Korzunin, E.P. Parfenov, N.A. Brovsky, V.Yu. Avdonin "Machines! continuous casting of blanks" Ural PR and advertising center! "Marat" Yekaterinburg 2004

It has also been established in practice that the presence of overheating in the specified zones of narrow walls is associated with a 3o decrease in the thickness of the side faces of the crystallizing shell in these places of growth of the continuously cast billet from Ga and the formation of its thinness. At the same time, longitudinal cracks may appear in areas located near the wide faces of the shell. Along with this, upon reaching a temperature above the recrystallization threshold, strengthening and destruction of the metal of the wall may occur in the specified places of the narrow walls. All this in the aggregate limits: h- the condition of using high indicators of pouring speed with ensuring the proper quality of 35 continuously cast blanks. co

The specified company has developed and applied in production a number of modern technical solutions to increase the pouring speed by optimizing the main parameters in the hydraulic system of water cooling of narrow walls, which has a significant impact on reducing the temperature of the edge of the working surface of the wall in them, which "include the following indicators with their conventional symbols : thickness and width of the wall Hs and Bc, depth and width of 70 channels Nk and Sk, distance between channels Ak, width of the section from the edge to the nearest channel At, width of the section Z c between the two nearest channels with a place for installing the pin Amk. with Data on temperature parameters Tr and Tc and the above parameters are given in the table, which shows similar parameters of narrow walls of other companies for comparison. what about - fell 00000003 wow? 8030 оо со "т с According to these data, crystallizers of the above-mentioned company with rectangular channels provide relatively better cooling indicators of zones near the edges of narrow walls due to the use of an improved device of stud fastening nodes between the water cooling channels closest to the edges (see the table). At the same time, in the following two structures of narrow walls to intensify the cooling of the rib zone with an additional channel of a smaller cross-section passing through the pins between the channels closest to it with fastening pins. In the wall with a thickness of 4 Ohm, the channel is made by means of an insert of a special design welded to the steel body. Thanks to the use of such the device made it possible to manufacture narrow walls with reduced thickness and with a reduced depth of channels, which 60 provided savings of copper up to 4395 compared to walls with cylindrical channels.At the same time, the walls are designed for pouring at a speed of 1.7-1.8 m/min.

The disadvantage of this design is that the installation of inserts with pins to the required depth of the copper wall requires the use of three rows of nodes for fastening it to the steel body instead of the two used in all known crystallizers. The construction of these walls is subjected to tests in the most experimental manner in the conditions of the NTMK, and the minimum indicators of the temperature of the working surface of the wall in the zones of the rib and its middle, which are 348 and 2912С, respectively, were also achieved.

There are well-known crystallizers of the firm "FAI" (Austria), in which, for the purpose of more intensive cooling of the ribs in the narrow walls, the near channels are made obliquely at an angle to them equal to 75" with an increase in length by approximately Zmm, which made it possible to obtain temperatures Tr and Tc equal to 358 and 3002C, respectively.

The given data allow us to come to the conclusion that the use of the most optimal parameters of water cooling of narrow walls by well-known companies helps to reduce the overall level of temperature indicators on their working surface both in the rib area and in the middle of the wall while simultaneously reducing its thickness. However, practically, the previously noted inequality of temperature values in the above 70 zones remained at the former level, showing that the temperature on the surface of the rib is higher than in its middle. At the same time, the minimum and maximum value of the rib temperature is in the range of 348-3902С, respectively, and in the middle of the wall it is 291-311960,

Moreover, the difference between these values is in the range of 56-829C

According to the research data of the company "Uralmash - MO", it is known that the lowest indicators of the above 72 temperature indicators (Tr and Ts) were obtained with a wall thickness of 35 mm. At this time, there is no data on the practical possibility of manufacturing and testing narrow walls with such a thickness. Along with this, it was also established that the problem of possible production of narrow walls from copper plates with a thickness of less than 40 mm in combination with a decrease in the depth of water cooling channels remains practically unsolved. The solution to this issue requires a corresponding change in the level of the location of the fastening pins in the copper wall.

Thus, it was established that this type of known crystallizers with narrow walls of a removable design does not provide the possibility of reducing the temperature of the working surface near the side faces of the narrow walls to the level of indicators in their middle due to the presence of pins for fastening the copper walls to the steel body in these places. Moreover, practically, for this reason, the problem of intensification of heat exchange in narrow walls due to the reduction of their thickness below 40 mm has not been solved.

The closest device for ensuring equalization of the temperature of the working surface along the entire width of the narrow walls due to the use of the minimum possible thickness of the copper layer in combination with the development of a new design for attaching them to the steel body is a crystallizer for continuous pouring of metals, which contains narrow walls of a non-detachable design, made of copper alloys, supplied with a clad layer located on the back side; water cooling system, formed on the 0.6-0.8 upper part of the narrow "2 walls by channels of cylindrical cross-section, and on the "input-output" and in the lower part of the narrow walls, the channels are made of a rectangular shape, which are closed with steel covers, rigidly fixed to the clad layer. (Patent of Ukraine for an invention Mo53984А IPC V22D 11/04 publ. 04/15/2003 p. 1

The disadvantage of the known crystallizer is that it contains a water-cooling system of working channels "- rectangular in cross-section, made instead of cylindrical working channels, only in the lower part of narrow

From the wall This excludes the possibility of making them with a thin main layer of copper due to the execution of (the) specified) rectangular channels at a shallower depth than that occupied by cylindrical channels.

The basis of a useful model is the task of developing a crystallizer for continuous pouring of metals, in which, due to a new form of structural elements, it is possible to manufacture narrow walls with a "main layer of copper alloys and a clad layer of steel with all working cooling channels made in their composition along the length of only a rectangular the shape of the cross-section of the channels of non-detachable design, the cavities - s of which are located in depth both in the weeping layer (ps) and in the main metal (pm). At the same time, it is possible to fasten narrow walls to the steel case by means of a device located outside the main layer of copper and the cooling channels located in it.

This technical solution eliminates the need to place fastening pins between the cavities close to the side faces of the water cooling channels. Together with this, it is possible to manufacture narrow c" walls of a non-detachable structure with the minimum possible thickness of the main layer of copper alloys due to the reduction of its part (Ppm) from the total depth of the channels (pk). Moreover, all channels along the width of the wall are made at the same distance from each other, which helps to equalize the temperature indicators of the working surface along the entire width of the narrow walls (Tr and Ts). t 50 To solve the task in the proposed crystallizer for continuous pouring of metals, which contains two narrow walls attached to the steel body with fastening pins with a copper and steel c2 clad layer located on the back side; a water cooling system formed on 0.6-0.8 of the upper part of the narrow wall by channels of cylindrical cross-section, and on the "input-output" and in the lower part of the walls, the channels are made of a rectangular shape, which are closed with steel covers rigidly fixed to the 22 clad layer, according to the useful model, all water-cooling channels along the width and length of the narrow walls are made of a rectangular cross-section (milled) with an individually adjustable heat dissipation system due to the fact that each such channel in the entire depth (NK) is contained in two layers of metals produced in one piece in a steel weeping layer, (ps) and another - mainly copper metal (pm). At the same time, the main indicator of this heat exchange is determined by the ratio of the dimensions of the part and the depth of the channel 60 contained in the copper layer to its total depth (pm/pK), which can be set in the range from one to zero along the length of each or group of channels. Moreover, the hydraulic balance in such channels is ensured by the use of a part of the channel contained in the steel weeping layer (ps).

At the same time, the sum of both parts is the total depth of the pk channel, i.e. pm-ps-NK. This is evidence that this design of rectangular channels on the entire length (length) of the wall, or its parts, can be performed because only in the copper layer and in two layers , or only in a steel weeping layer.

In combination with this, in the proposed crystallizer, the fixing pins are located outside the copper and steel clad layers, but passed through the steel body and fixed inside the extensions rigidly attached to the clad layer and placed inside the phthalic body.

Moreover, all rectangular water cooling channels are made at the same distance from each other along the entire width of the wall, which contributes to the equalization of heat exchange from their side faces (Tr) to the level of the middle of the wall (Ts).

The presence of rectangular channels in combination with extensions on two-layer narrow walls provides the possibility of improving the following technical and economic indicators in the proposed crystallizer.

Production of walls in large-slab and other MBL3Z with a thin main layer of copper with a thickness index of 7/0. No, of the order of 40mm and less when the value of the useful thickness is up to 30mm, which is performed by reducing the depth of the channels contained in the copper layer to the smallest level that ensures normal thermal operation of the walls. At the same time, it is not necessary to implement any additional technological solutions, such as, for example, in the narrow walls of the company "Uralmash - MO" with a thickness of 40 mm with channels 11 mm deep, in which the thin copper walls are firmly fixed to the steel body with fastening pins located at the level depth of channels, it was necessary to install them in three rows instead of the usual two rows.

In the proposed crystallizer, it is advisable to further reduce the thickness of the base metal from copper in two-layer racks to 35 mm and less in the above order by reducing the rectangular channels of the part contained in the copper layer to 5 mm and less. At the same time, in a two-layer metal, it is performed based on the calculation of obtaining the required speed of the cooler in it. Intensification of heat dissipation and its more uniform distribution along the width of the wall is also achieved by reducing the value of the distance between the cavities of the above-mentioned channels (Ak).

Durability in operation of the mentioned channels as part of two-layer walls is provided by covers that cover their cavities and are welded to the steel clad layer. Determining the thermal performance of such walls is somewhat complicated due to the fact that the process of heat transfer in their water cooling channels takes place with the help of two dissimilar metals contained in the main layer of copper and in the weeping layer of steel. At the same time, this contact between the layers of the specified metals is contained along the planes (width) of the partitions between the channels, on which the boundary of the two layers consists of jointly deformed molecular particles, firmly connected to each other during the manufacture of two-layer plates, for example, by the method of welding with impulse loads (explosion ). Moreover, with this method, a wave-like shape of the boundary of metal layers will be formed, which should also contribute to the intensification of heat transfer between two dissimilar metals. The efficiency of heat transfer in such a design of water cooling channels was determined to be the most expedient, guided in part by the available practical data. with

For example, there is a well-known advanced crystallizer of the company "Uralmash - MO", in which water cooling channels of a rectangular cross-section are made not in a copper wall, but in a steel body. According to the results of his ch-z5 test, it was established that such a cooling system leads to a deterioration of the thermal condition of the wall. with

However, based on the obtained results, the company's specialists recommended that the width of the above-mentioned channels exceed the distance between them. This should help to increase the contact area of the copper wall directly with the cooler at the bottom of the channel. Moreover, the removal of heat from the copper wall to the steel partitions can be significantly difficult or completely absent due to the formation of coarse "oxides" or gaps in these places of contact due to thermal grooving of the thin copper wall. Figure 1 shows a cross-section of the right part of the proposed crystallizer with rectangular channels made of two-layer metal in combination with a new design of a device for fastening two-layer narrow walls to a steel body through extensions.

The crystallizer contains a steel body 1 and two two-layer narrow walls consisting of the main copper layer 2 and a steel clad layer 3 located on the back side of the wall. c In the narrow wall along the length and width, all channels of rectangular cross-section 4 are contained, the cavities of which in depth (PK) are made in general both in the copper layer 2 (pPm) and in the steel planing layer, Z (ps). -th Rectangular channels 4 are made of an integral design and are closed with steel covers 5, firmly welded to the clad layer C located on the back side of the wall. At the same time, the rear side of the wall 5or is firmly fixed to the steel body 1 by means of the extension 6, also welded to the clad layer 3, into the threaded hole of which the fastening pin 7, located outside the native layer 2, is screwed. The extension o is located with a certain gap in the cavity steel body 1 with a hole in it for installing a pin 7.

Extensions can be welded both to the clad layer, directly, and to the channel covers 5, so their installation locations are determined structurally. At the same time, in the narrow walls of the proposed crystallizer, the distance from the extreme channel 4 to the side faces of the wall is about 15-20 mm, and on the other part of the wall width, the channels are made at the same distance from each other along the entire length of the wall. c The proposed crystallizer works in the following way. Liquid metal from the intermediate ladle is fed into the working cavity of the crystallizer, formed by the cooled copper layers 2, through the immersion glass. Under the influence of the cooled liquid, the process of forming the crust of the continuously cast preform, which in the upper part of the crystallizer is in close contact with the copper layers of 2 narrow walls, begins.

Rectangular channels 4, made in the immediate vicinity of the extreme side faces on the former areas of installation of fastening pins, contribute to the increase of cooled surfaces in this zone of the copper layer 2 and intensifies the process of heat removal from the hardening shell from the cast billet. As a result, the condition of equalization of temperature values on the working surface near the edges of Tr and in the middle of 65 Ts is ensured, which is an essential indicator when applying a high speed of liquid metal pouring. Further, the hardened shell shrinks away from the walls of the crystallizer, forming a gap. Therefore, the effective share of loads on narrow walls is insignificant and largely depends on their correctly set conicity. At the same time, the strength of the welded connection of the extension 6 with the clad layer C is at a high level, as is the strength of the welding of the steel clad layer, C with the copper layer 2 narrow walls.

The application of the proposed structure of the crystallizer allows: - to equalize the temperature of the working surface of the walls in the zone of the side faces Tr to the level of the indicator in its middle Ts due to the intensification of the heat dissipation by rectangular channels made in this zone, as a result of which it is possible to obtain a workpiece with a uniform thickness in the hardened shell side faces; 70 - to make two-layer narrow walls with a thin main layer of copper (40 mm or less), which provides savings of this metal by 5095 or more compared to walls containing cylindrical cooling channels. - to ensure the possibility of pouring liquid metal with increased rates of pouring speed, typical for crystallizers with rectangular channels, equal to the order of 1.5-1.7 m/min.

Claims (2)

19 Formula of the invention 1. Crystallizer for continuous pouring of metals, containing two narrow walls attached to a steel body with fastening pins with a copper layer and a steel clad layer located on the rear side, a water cooling system formed by channels, which is distinguished by the fact that in the crystallizer along the entire width and along the length of the narrow walls, the channels are made in a rectangular cross-section, the cavity of each of which is located along the entire depth both in the part of the steel clad layer and in the part of the base metal made of copper, and the surface of the steel clad layer is equipped with attachments rigidly attached to its surface, for example, by welding , and the extensions are made with vertically distributed threaded holes for fastening pins. 25. higher . . not 2. Crystallizer according to claim 1, which differs in that all rectangular channels are made in width and length - narrow walls at the same distance from each other. C. Crystallizer according to claims 1, 2, which differs in that the rectangular channels of the steel clad layer in the upper part are closed with steel welded covers. o s (ge) "-- Zo "o - and? o - so ko c2 60 b5