RU2486027C1 - Device for continuous casting, rolling and forming of rods - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy, in particular, to continuous casting with forming. Proposed device comprises mixing furnace, rolls with groove and flange making working gage. Female die with cooling channels at outer surface is arranged and gage outlet. Cooled channels are furnished with through holes extending through female die lateral outer surfaces to communicate with coolant feed and discharge channels. Said cooled channels are covered from outside by plates. Through hole cross-section areas and those of coolant feed and discharge channels are equal. Relationship between coolant discharge channel cross-section area to that of coolant feed makes over 1.5 and is define by the following relation: $${\nu }_f\le \frac{{\rho }_w{\nu }_w{F}_w}{{\rho }_f{F}_f},$$

where ρ_f, ρ_w are coolant fluid and vapor densities, ν_f, ν_w are coolant fluid and vapor velocities, F_f, F_w are cross-section areas of coolant feed and discharge channels.

EFFECT: higher efficiency of cooling produced rods.

2 dwg, 1 ex

Description

The present invention relates to the field of metal forming and can be used to produce wire rod, rods and profiles mainly from aluminum alloys by continuous casting, rolling and pressing.

A device is known for continuous casting and pressing of hollow profiles (RF Patent 2200644, IPC B22D 11/06, B21C 23/08. / Sidelnikov SB, Dovzhenko NN, Grishechkin AI, Sidelnikova ES) comprising a mixer oven, a roller with a stream and a roller with a protrusion, having cooled cavities and forming a working gauge, at the outlet of which a matrix with wedge-shaped cooled cavities is installed.

This device ensures the continuity of the process of obtaining seamless hollow profiles. However, in this device, heat removal during crystallization and deformation occurs using wedge-shaped cooled cavities in the matrix, which does not provide sufficient cooling efficiency, does not allow to achieve maximum productivity of the manufacturing process of profiles, and to stabilize the temperature conditions during the process and the quality of the profiles. Stabilization of the temperature conditions of the matrix is especially important for continuous combined processes of casting, rolling and pressing (hereinafter - SLIPP). It should also be noted that the implementation of wedge-shaped cooled cavities inside the matrix complicates its design, leads to the appearance of significant thermal stresses in their volume and, as a result, significantly reduces its reliability during operation. (Dovzhenko N.N. Pressing of aluminum alloys: modeling and control of thermal conditions: monograph [Text] / N.N. Dovzhenko, S.V. Belyaev, S.B.Sidelnikov et al. // - Krasnoyarsk: INC Siberian Federal University, 2009 . - 256 p.).

The closest in combination of essential features, in technical essence and the achieved result is a device for continuous casting and pressing of hollow profiles (Patent 2335376 RF, IPC B22D 11/06, B21C 23/00 / Belyaev S.V., Dovzhenko N.N., Sidelnikov S.B. et al.), Including a mixer oven, a roller with a stream and a roller with a protrusion, having cooled cavities and forming a working gauge, at the exit of which a matrix is installed, on the end outer surface of which is in contact with the rollers, made cooled channels. This device ensures the continuity of the process of obtaining profiles by the SLIPP method. However, during operation of this device, a burr from a deformable metal is formed on the surface of the rolls, which partially or completely blocks the cooled channels on the outer end surface of the matrix in contact with the rolls and disrupts the circulation of the refrigerant, which reduces the intensity and stability of heat removal up to its full termination. As a result, the thermal conditions of the SLIPP process are destabilized, which causes overheating of the tool and the deformable metal, the appearance of defective products and leads to a forced stop of this device. All this negatively affects the performance of the SLIPP process and the quality of the resulting profiles. In addition, sometimes the manufacture of cooled channels on the end outer surface of the matrix in contact with the rolls is impossible due to the small transverse dimensions of the matrix for the manufacture of profiles of a small cross section. It should also be noted that in this device it is impossible to use evaporative cooling, which is more efficient than cooling with flowing coolant (Chernomurov F.M. On the possibility of using a heat pipe to intensify the pressing process [Text] / F.M. Chernomurov, V.A. .Kuzmenko, N.G. Parfentiev, S.V. Belyaev // Light alloy technology. 1984. July. - P. 51-55).

The main objective of the invention is to increase the performance of continuous casting, rolling and pressing and the quality of the wire rod by improving cooling efficiency.

This object is achieved in that in a device for continuous casting, rolling and pressing of wire rod, including a mixer oven, a roller with a stream and a roller with a protrusion, having cooled cavities and forming a working gauge, at the exit of which there is a matrix having cooled channels made on its outer surface according to the invention, the cooled channels are provided with through holes passing through the lateral, outer surfaces of the matrix, communicating with the channels for supplying and discharging refrigerant, and the outside is cooled the channels are hermetically closed by plates, while the cross-sectional areas of the holes and the channels for supplying and discharging refrigerant connected to them are respectively equal to each other, but the cross-sectional area of the channel for discharging refrigerant is larger than the cross-sectional area of the channel for delivering refrigerant more than 1, 5 times, and the maximum rate of supply of refrigerant into the cooled channels is determined from the ratio:

$${\nu }_{\mathrm{AT}}\le \frac{{\rho }_P{\nu }_P{F}_P}{{\rho }_{\mathrm{AT}}{F}_{\mathrm{AT}}}$$

where ρ _B , ρ _P - the density of the liquid and the vapor of the refrigerant;

ν _B , ν _P - the velocity of the liquid and vapor of the refrigerant;

F _B , F _P - the cross-sectional area of the channels for supplying and discharging refrigerant.

The design features of the claimed device compared to the prototype, characterized by distinctive features, can improve the performance of continuous casting, rolling and pressing and the quality of the wire rod.

The implementation of sealed, closed with the help of plates, cooled channels on the outer surface of the matrix in contact with the rolls will not affect the intensity of heat removal directly from the deformation zone, and at the same time, both the matrix and the rolls will be simultaneously cooled. But in this case, the possibility of a burr from a deformable metal getting into the cooled channels and, as a result, failure of the cooling system of the proposed device, i.e. the reliability and uninterrupted operation of the proposed device during the SLIPP process will increase.

In addition, the design of the channels, subject to the following conditions, is that the cross-sectional areas of the through holes and the channels for supplying and discharging refrigerant connected to them are respectively equal to each other, while the cross-sectional area of the channel for discharging refrigerant is larger than the cross-sectional area of the channel for supplying refrigerant more than 1.5 times, will ensure the implementation of evaporative cooling of the matrix.

The maximum rate of supply of refrigerant to the cooling zone should be determined from relation (1), which is associated with a restriction on the hydrodynamic locking of the steam outlet channel when the steam reaches the speed of sound. Otherwise, the directional circulation of the refrigerant is disrupted and the cooling intensity is sharply reduced.

It should be noted that during evaporative cooling, the heat removed is mainly spent on the formation of steam. Since the heat of vaporization is high, with evaporative cooling, the heat sink rate at the same feed rate can be two orders of magnitude higher than with flow cooling. A positive feature of evaporative cooling is that the heat exchange process, despite its intensity, becomes sufficiently controlled, since the intensity of heat removal almost linearly depends on the flow rate of the refrigerant into the cooling zone, i.e. the efficiency of cooling and controlling the thermal conditions of the SLIPP process increases.

Thus, there is a causal relationship between the hallmarks and the task at hand. The implementation of the device for continuous casting, rolling and pressing of wire rod having the above set of distinctive features, can improve the performance of continuous casting, rolling and pressing and the quality of the wire rod.

The invention is illustrated graphic materials.

Figure 1 shows a General view of the device in section during the process of continuous casting, rolling and pressing of wire rod, and figure 2 is a section of the matrix aa in figure 1. The inventive device for continuous casting, rolling and pressing of wire rod includes a mixer-mixer 1 with a melt 2, a roller 3 with a stream and a roller 4 with a protrusion, forming a closed gauge, blocked at the outlet by a matrix 5 with cooled channels 6, made on the outer side surface of the matrix 5 in contact with the rolls 3 and 4. The cooled channels 6 are provided with through holes 7 and 8 passing through these lateral surfaces and communicating with the channels for supplying 9 and removing refrigerant 10, and the cooled channels are sealed outside Lastin 11.

In addition, the cross-sectional areas of the through holes 7 and 8 and the channels for communicating with them for supplying 9 and removal of refrigerant 10 are respectively equal to each other, while the cross-sectional area of the channel for removing 10 refrigerant is larger than the cross-sectional area of the channel for supplying 9 refrigerant more than 1.5 times, and the maximum rate of supply of refrigerant into the cooled channels is determined from relation (1).

The device operates as follows.

First, the molten metal 2 is poured into the mixer-mixer 1, and its crystallization on the surfaces of the rolls 3 and 4 begins. Then, the crystallized metal is captured by the rolls 3 and 4, is deformed in the closed gauge between the rolls 3 and 4, and extruded through the working channel of the matrix 5 in the form wire rods 12. At the moment the melt enters the mixer-mixer 1, refrigerant is supplied to the cooled channels 6 of the matrix 5.

Example. Using the SLIPP laboratory unit on the basis of the DUO 200 rolling mill, continuous casting, rolling and pressing of wire rod (bar, profile) with a diameter of 6 mm from an aluminum alloy of grade A7 was carried out. The melt temperature was 700 ° C and the pressing temperature was 540 ° C. Pressing wire rod was carried out through a matrix with a hood 10 using a prototype and the inventive device. At the same time, the change in the output temperature of the wire rod and the maximum possible pressing rate by the appearance of cracks on the surface of the wire rod were recorded. During the appearance of a burr on the surface of the rolls in the prototype, the surface of the cooled channels was blocked by a burr of deformable metal at the contact of the rolls and the end surface of the matrix, where the cooled channels are located, which stopped the access of the refrigerant to the cooled channels and disabled the matrix cooling system. As a result, the output temperature of the wire rod increased sharply, reaching a limit value - the pressing temperature of 590 ° C, when the active formation of cracks on the surface of the wire rod began, i.e. the appearance of marriage. Therefore, a forced stop of the device was required. In the inventive device, the cooled channels were made on the outer side surface of the matrix in contact with the rolls and provided with through holes passing through these side surfaces, while the cross-sectional areas of the through holes and the channels for supplying and discharging refrigerant communicating with them were respectively equal , and the cross-sectional area of the channel for refrigerant removal was larger and equal to 6 mm than the cross-sectional area of the channel for supplying refrigerant, equal to 4 mm, more than 1.5 times (p about the fact - 2.25 times), and the maximum rate of supply of refrigerant into the cooled channels was determined from the relation (1):

$${\nu }_{\mathrm{AT}}\le \frac{{\rho }_P{\nu }_P{F}_P}{{\rho }_{\mathrm{AT}}{F}_{\mathrm{AT}}}=0.585\cdot 2.25=\mathrm{one,}3m/\mathrm{from}.$$

The formation of a burr on the surface of the rolls in the inventive device practically did not affect the cooling rate of the working tool, because outside, the cooled channels were hermetically sealed with plates. The SLIPP process using the inventive device has been stable for a long time and was stopped after processing all the molten metal in the mixer. At the same time, due to the evaporative cooling of the matrix, it was possible to increase the process productivity up to 30% and at the same time keep the pressing temperature at the required constant level of 540 ± 5 ° C, and there were no defects on the surface of the wire rod.

Thus, the use of the inventive device in comparison with the prototype can improve the performance of continuous casting, rolling and pressing due to the absence of forced stops and increase the speed of the SLIPP process and the quality of the wire rod.

Claims (1)

A device for continuous casting, rolling and pressing of wire rod, including a mixer-mixer, a roller with a stream and a roller with a protrusion, having cooled cavities and forming a working gauge, at the outlet of which there is a matrix having cooled channels made on its outer surface, characterized in that the cooled channels are provided with through holes passing through the lateral outer surfaces of the matrix, communicating with the channels for supplying and discharging refrigerant, and the cooled channels are sealed on the outside by plates, When this cross-sectional areas of apertures and channels communicated with them for supplying and removing coolant are respectively equal to each other, and the ratio of the cross section of the channel for discharging the refrigerant to the channel cross-sectional area of the refrigerant inlet is greater than 1.5 and is determined from the following relation:
$${\nu }_{\mathrm{at}}\le \frac{{\rho }_P{\nu }_P{F}_P}{{\rho }_{\mathrm{at}}{F}_{\mathrm{at}}},$$

where ρ _B , ρ _p - the density of the liquid and vapor of the refrigerant;
ν _in , ν _p - the velocity of the liquid and vapor of the refrigerant;
F _in , F _p - the cross-sectional area of the channels for supplying and discharging refrigerant.

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