RU2725377C1 - Crystallizer for vertical ingots casting - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to continuous and semi-continuous pouring of metals. Proposed crystalliser comprises housing with coolant feed and discharge channel, distribution chamber and chamber (9) of ingot primary cooling, separated by at least one diaphragm (6) and one vertical baffle (5) and casting chamber (4). Area of the slots or holes (11) in the diaphragm or the area of the gap between the diaphragm and the housing increases as they move away from the channel for supply of cooling liquid to the opposite in diameter position. Thus, cooling liquid flow through diaphragm increases with distance from coolant supply channel to the opposite in diameter position. According to another embodiment, chamber of primary cooling of ingot is formed by cavity of multi-start spiral cutting (12), each turn of which makes at least one revolution around casting chamber.EFFECT: higher quality of cast ingot due to improved conditions of its cooling.8 cl, 2 dwg, 2 ex

Description

The invention relates to the field of metallurgy and is intended for use in continuous and semi-continuous casting of metals, in particular, aluminum-based alloys.

Numerous structural solutions are known for molds for vertical casting of ingots with an inlet for supplying molten metal and an outlet for drawing an ingot, aimed at regulating the cooling intensity of the walls of the mold chamber (forming channel) of the mold and cast ingots. A common solution is the chambers for receiving and distributing coolant in the mold housing concentrically located relative to each other. Particular solutions include various designs of cooling chambers, methods for supplying and distributing coolant, including the simplest (RU 2268105, US 7011140, СН 665575), double-circuit (RU 113685, RU 2111825) and two-level (RU 2152287, US 5685359) camera designs, cooling by water and gas (RU 2111825, US 4693298, US 7011140), various methods of supplying lubricant (RU 113685, CH 665575, US 4693298). As a rule, the proposed solutions are complex, offering at the same time several measures that improve the quality of the ingots.

Among the known solutions, a certain group consists of devices that provide effective primary cooling of the walls of the mold of the mold and secondary cooling of the ingot.

In particular, it is known a device for casting ingots according to patent RU 100931 (publ. 10.01.2011, B22D 11/055), containing a single-chamber crystallizer of the primary cooling zone, into which the cooling liquid (water) flows through several consecutive nozzles installed at an angle of 30 ° to the cylindrical forming surface of the mold, and the zone of direct secondary cooling of the ingot. The main disadvantage of the device is the large number of water supply hoses, which complicates the cooling system due to the need to have additional pipelines, hoses, pipes, shut-off valves, etc., complicates its maintenance and makes it difficult to cast. In addition, with a decrease in the pressure of the cooler, irreversible thermal deformation of the walls of the casting chamber is very likely.

A device for casting ingots according to the patent RU 113685 (publ. 02/27/2012, B22D 11/041), containing isolated concentrically arranged relative to each other annular chambers of initial and additional cooling, in which the supply of coolant is limited by two pipes for its reception and distribution, is known. This to some extent reduces the difficulties encountered in the implementation of the device, however, this decreases the uniformity of cooling of the ingot and increases the likelihood of destruction of the ingot during and after casting.

The device for casting ingots according to patent RU 2152287 (publ. 10.07.2000, B22D 11/04) with a primary cooling zone, consisting of upper and lower chambers separated by a horizontal partition, provides a reliable supply of coolant (water) from a single pipe. However, one-piece housing makes it difficult to service the mold. The uniform cooling of the ingot is also insufficient.

Closest to the proposed technical essence is the mold for vertical casting of ingots according to patent RU 2281183 (publ. 08/10/2006, B22D 11/04, B22D 11/07), which contains a housing with a channel for supplying coolant, isolated from each other distribution and cooling chambers separated by horizontal and vertical partitions, providing the possibility of uniform flow of coolant due to gaps relative to the housing or the gap in the partition, and channels for draining the coolant, providing secondary direct cooling of the ingot. The mold according to patent RU 2281183 is taken as a prototype.

The design of the mold provides a fairly uniform structure of the ingot. The disadvantage of this device is the unevenness of heat dissipation due to the remaining significant unevenness of the flow of coolant through gaps and gaps.

The main objective of the invention is to improve the quality of the cast ingot by improving its cooling conditions.

The technical result of the invention is effective and uniform cooling of the walls of the casting chamber and uniform heat removal from the wall of the casting chamber of the mold, regardless of the difference in temperature of the coolant over the cross section before entering the cooling chamber. As a result of uniform heat removal, the likelihood of breakthrough of liquid metal during casting is also reduced.

The technical result is achieved in that in a mold for vertical casting of ingots having zones of primary and secondary direct cooling of the ingot, comprising a housing with a channel for supplying (supplying) coolant (pipe), distribution and cooling chambers separated from each other, separated by partitions, and channels coolant vents:

- uniform flow of coolant (water) from the distribution chamber into the cooling chamber provides either a variable gap of the diaphragm (partition) relative to the housing, or cuts (slots) or holes in the diaphragm (partition), the cross-section and location of which increases the flow of coolant (water) through the diaphragm with distance from the supply channel (pipe) to the opposite position in diameter;

- the cooling chamber is fully or partially formed by a multi-helical cavity, each turn of which makes at least one revolution around the casting chamber; this ensures uniform cooling of the walls of the mold chamber of the mold and ingot.

In FIG. 1 shows an example of the design of the proposed mold. The mold body is an outer shell 7, covered with lids 2 and 3, inside of which a casting chamber is located 4. The inner cavity of the mold is divided by a vertical partition 5 into a distribution chamber, which, in turn, consists of a receiving 7 and a transfer case 6 separated by a horizontal partition (diaphragm) 6 cavities, and the primary cooling chamber of the ingot (cooling chamber) 9. The pipe 10 in the shell 1 serves as the supply channel of the cooling liquid (water) to the receiving cavity 7 of the distribution chamber.

Uniform in diameter (regardless of the position relative to the supply channel), the flow of coolant (water) through the diaphragm 6 from the inlet 7 to the dispensing cavity 8 of the distribution chamber and then into the primary cooling chamber 9 in this example is ensured by openings 11 in the diaphragm 6, the cross-sectional area of which increases with distance from the pipe 10 to the opposite position in diameter. In particular, the simplest solution is to increase the cross-sectional area of the holes according to a linear law, for example, through holes of equal diameter, arranged with a variable pitch (Fig. 2).

The design of the diaphragm 6 may be different: with holes, as in FIG. 2, or slots (slots) of variable cross-section, with a variable gap between the diaphragm and the housing due to the eccentric displacement of the diaphragm relative to the axis of the mold or the like. In this case, an increase in the throughput of the diaphragm as it moves away from the nozzle 10 to an opposite position in diameter ensures a uniform flow of coolant through it, which minimizes the influence of the stagnant zone from the side opposite to the supply nozzle 10. Moreover, the total cross-sectional area of the gaps between the diaphragm and the housing or slots in the diaphragm 6 (throughput) should correspond to the throughput of the pipe 10. The optimal ratio of the cross-sectional area of the coolant supply channel to the total cross-sectional area of the gaps, holes or slots in the diaphragm is 0.9-1.2.

The primary cooling chamber 9 represents a cavity between the wall of the casting chamber 4 and the vertical partition 5. Increasing the uniformity of the heat sink can be achieved due to the fact that the cavity forms a multi-start (in FIG. 2 three-way) spiral cutting 12 in the wall of the casting chamber. Each turn of the cut makes at least one revolution around the casting chamber. Coolant (water) moves along the spiral channels of the cutting 12, cooling the wall of the casting chamber 4.

In the lower part of the primary cooling chamber 9, a number of holes 13 are made, which are channels leading off the coolant through which it enters to directly cool the ingot leaving the crystallizer.

The primary cooling chamber 9 can be formed in whole or in part by a cavity of multi-helical spiral cutting 12, if, due to structural considerations, the throughput of the cavity of spiral cutting 12 is insufficient to ensure the balance of heat coming from the cast ingot and removed by the coolant. If it is necessary to increase the throughput of the primary cooling chamber 9 between the vertices of the spiral cut 12 in the wall of the casting chamber 4 and the vertical partition 5, an additional gap can be made.

The throughput of the holes 13 should provide the above heat balance. The throughput of the primary cooling chamber 9 should provide a supply of coolant in front of the holes 13. The ratio of the cross-sectional area of the multi-helical spiral cutting cavity to the total area of the holes 13 should be ≥ 1.1.

In the lower part of the primary cooling chamber 9, a cavity 14 can additionally be made, which serves as a shock absorber for the pressure of the coolant. In this case, the ratio of the cross-sectional area of the multi-start spiral cavity of the primary cooling chamber 9 to the cross-sectional area of the annular channel 15 and the cross-sectional area of the annular channel 15 to the total area of the openings 13 should be ≥ 1.1.

The design of the mold may include:

- the use of methods for distributing coolant as by means of a diaphragm 6, by means of spiral cutting 12 separately or jointly,

- combined execution of parts (for example, execution of a cover 3, a vertical partition 5 and a diaphragm 6, as one part, a spiral cut 12 in a vertical partition, etc.

Structurally, the mold with the proposed principle of coolant distribution and cooling of the walls of the casting chamber can be made with a lubricant supply system, in a two-level design, with a gas screen to reduce the cooling rate of the ingot, etc.

The mold as part of a continuous and semi-continuous casting of metals works as follows.

Before casting, a liquid lubricant is applied to the inner surface of the wall of the mold chamber 4 of the mold by any known method. Through the pipe 10 in the receiving cavity 7 of the distribution chamber is supplied coolant (water) flowing through the holes 11 in the diaphragm 6 into the dispensing 8 cavity of the distribution chamber. The cross section and location of the holes 11 provides a uniform in diameter, sufficiently laminar flow of fluid coming from one inlet pipe 10 through the diaphragm 6, regardless of the stagnation zone in front of the diaphragm. Passing through the channels of multi-helical spiral cutting 72 of the primary cooling chamber 9, the fluid flow cools the wall of the casting chamber 4. The multi-helix ensures the intake of coolant behind the diaphragm 6 from different (in diameter) places. At least one revolution passes around the cooling fluid in a spiral around the casting chamber 4. Thus, the cooling conditions of the walls of the casting chamber 4 are not so dependent on the laminarity, flow rate and possible difference in temperature of the cooling liquid before entering the cooling chamber 9. After the cooling chamber 9, well-mixed coolant through the holes 13 enters the ingot, providing its secondary direct cooling.

The molten metal is poured into the mold and the ingot is drawn using known technology.

Case Studies

Example 1. Casting ingots with a diameter of 100 and 120 mm from aluminum alloy AD31. The ingot drawing speed was 150 mm / min (2.5 mm / s). High surface quality of the ingots was noted with a 2-2.5-fold increase in the ingot drawing speed compared to the prototype.

Example 2. Casting ingots with a diameter of 120 mm from aluminum alloy 1570. The drawing speed of the ingot was 135 mm / min (= 2.25 mm / s). Satisfactory surface quality and a uniform fine-grained structure over the cross section of the ingot were noted. Breakthroughs of liquid metal during casting were absent, while on the prototype they took place.

Thus, the proposed mold due to uniform cooling provides a fine-grained, more uniform in cross section and height of the ingot structure and a more stable casting process compared to the prototype.

Claims (8)

1. The mold for vertical casting of ingots, comprising a housing with a channel for supplying and discharging coolant, a distribution chamber and a primary cooling chamber of the ingot, separated by at least one diaphragm and one vertical partition, characterized in that the area of the slots or holes in the diaphragm or the gap area between the diaphragm and the casing is made to increase with increasing distance from the channel for supplying coolant to the opposite in diameter position to ensure an increase in the flow of coolant through the diaphragm as it moves away from the channel for supplying coolant to the opposite in diameter position. 2. The mold according to claim 1, characterized in that the total cross-sectional area of the slots or holes in the diaphragm or the cross-sectional area of the gap between the diaphragm and the housing increases with distance from the supply channel to the opposite diameter position according to a linear law. 3. The mold according to any one of paragraphs. 1, 2 characterized in that the total cross-sectional area of the slots or holes in the diaphragm or the cross-sectional area of the gap between the diaphragm and the housing is 0.9-1.2 cross-sectional area of the channel for supplying coolant. 4. A mold for vertical casting of ingots, comprising a housing with a channel for supplying and discharging coolant, a distribution chamber, a primary cooling chamber of the ingot separated by at least one diaphragm and one vertical partition, and a casting chamber, characterized in that the primary cooling chamber the ingot is formed by a cavity of multiple helical cutting, each turn of which makes at least one revolution around the casting chamber. 5. The mold according to claim 4, characterized in that an annular gap is additionally made between the vertices of the spiral cut and the vertical partition. 6. The mold according to any one of paragraphs. 4, 5 characterized in that the ratio of the total cross-sectional area of the cavity of multiple helical cutting to the total area of the holes made in the channel for draining the coolant from the primary cooling chamber is ≥1.1. 7. The mold according to any one of paragraphs. 4-6 characterized in that an additional cavity is made in the lower part of the primary cooling chamber, which serves as a shock absorber for the pressure of the coolant. 8. The mold according to claim 7, characterized in that the ratio of the total cross-sectional area of the cavity of multiple helical cutting to the cross-sectional area of the channel for supplying coolant to the additional cavity, as well as the cross-sectional area of the channel for supplying coolant to the additional cavity, to the area of the channel for draining coolant from the chamber primary cooling is ≥1.1.

Images