RU1802741C - Method of manufacturing ingots on casting conveyor machine - Google Patents

Abstract

Usage: in metallurgy, when casting iron on conveyor machines. SUMMARY OF THE INVENTION: at the initial section of a conveyor belt equal to 0.2-0.3 of its length, the air-water mixture is supplied from below to the molds, and above, at a section of 0.005-0.01 lengths of the conveyor, compressed air is supplied at a speed of 8-10 m / s. Above, in a section from 0.2-0.3 to 0.7-0.8 of the length of the conveyor, a water-air mixture is supplied. The flow rate of the cooler is increased from the boundary, the upper cooling zone to the maximum, and the air flow rate is reduced to the minimum in the section 0.55-0.65 of the conveyor length. 1 table, 1 zpp-filter, 1 silt.

Description

The invention relates to metallurgy, in particular to cast iron casting on a conveyor machine.

The aim of the invention is to increase the durability of the mold, improve the quality of the grinders and increase the productivity.

The essence of the method is as follows. The molds of the conveyor machine are filled with liquid metal and, as the molds are moved, the surfaces of the molds and castings are cooled by a water-air mixture.

In the initial section of the conveyor, equal to 0.2-0.3 of its length L, the water-air mixture is fed to the molds from below, and in the next section from 0.2-0.3 to 0.7-0.8 of its drins, this mixture is fed to molds and castings from above, moreover, the flow rate of the cooler is increased from the boundaries of the upper cooling zone & to the maximum value, and the air flow rate is reduced to the minimum value in the section 0.55-0.65 of the conveyor length. In addition, in the initial section of the upper cooling zone, comprising 0.005-0.1 conveyor lengths, a stream of compressed air is supplied to the surface of the molds and castings at a speed of 8-10 m / s,

The cooling of the mold from below to (0.2--0.4) L facilitates the exit of gas bubbles and non-metallic inclusions to the surface of the casting, which improves its quality; on the other hand, irrigation from below intensifies the cooling process, the hardening and cooling of the lower part of the casting. Irrigation of the mold from below the area (0.2-0.3) L is impractical, since by the 40th second the lower part of the casting shell reaches a thickness of 5-7 mm, which, together with the mold wall and the heat-insulating layer of lime on the mold contact surface, casting is up to 40 mm thick. having significant thermal resistance. To the 40th. second, which corresponds to (0.2-0.3) L at

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the length of the conveyor is 42-43 m and speeds up to 16 m / min. the upper part of the casting, due to radiant heat transfer, hardens to a depth of several millimeters, which means that it is not possible to float further to the surface of non-metallic inclusions and makes it possible to start upper cooling. The beginning of the upper cooling and the termination of the lower one by (0.2-0.3) L helps to prevent overcooling of the mold itself, with very little cooling of the casting. The establishment of a different boundary of the upper cooling zone in the area (0.7-0.8) L is due to the fact that by the 120th second the surface temperature of the casting reaches 60-100 ° С (at a water temperature of 30-60 ° С) and even at significant Cooler costs (up to 20 mg / m2С) remove insignificant heat fluxes, while excess water cools the mold, lowering its average temperature below 400 ° С. The latter is unacceptable, as when the mold moves back to the pouring place (movement time 200 s), a heat-insulating layer of lime is applied to it. If moisture is retained in the layer when cast iron is cast, the surface quality and the quality of the casting as a whole are impaired. Setting the maximum value of the flow rate of the cooler to (0.55-0.65) L is due to the following circumstances: To achieve an average heat removal from the casting at the level of 4-15 MW / m2, providing the required average temperature of the casting at the conveyor outlet 200-600 ° С , the average flow rate of the cooler in the upper cooling zone should be 4.5-12 m / h. However, the implementation of cooling regimes with maximum values closer to the initial section of the conveyor belt, for example, by (6.4-, 0.45) 1 (65-70 s, cooling), leads to an increase in the likelihood of cracking, since the casting completely hardens after 80-100 s, cooling. Powerful irrigation: the curing of a completely uncured casting, taking into account the required average level of heat removal intensity, negatively affects its quality (formation of internal cracks). In addition, the displacement of the maximum flow area leads to a breakthrough of the cooler flowing down the conveyor (angle of inclination 7 °) beyond the lower boundary of the cooling zone (0.2-0.3) L

The drawing shows the experimental curves of the cooling zone of the casting, 2.5 - curves of the flow rate of compressed air, 3.4 - curves of the flow rate of the coolant. The distribution of the cooler in the upper cooling zone (drawing, curves 3, 4) shows the maximum achievable values

costs at which the cooler does not cross the boundaries of the cooling zone (0.2-0.8) L, This effect is achieved in conjunction with the distribution of compressed air flow

(drawing, curves 2, 5), while compressed air cuts off the flowing streams at the lower boundary and blows off the remnants of the cooler on the upper boundary.

In the presence of a significant amount of non-metallic inclusions in cast iron, in particular graphite, to remove the crust formed by these inclusions upon surfacing on the surface of the casting, in the initial section of the upper cooling zone,

5 constituting (0.005-0.01) L, a stream of compressed air is fed to the tape at an average speed of 8-10 m / s. This provides graphite deflation, cracking, and film deflation at non-metallic values with

0 of the casting surface, thereby improving heat removal. The film is removed in the area of (0.05-0.01) L in 1.5-2 s, so that at air flow rates of 8-10 m / s and achievable heat removal up to 0.18 MW / m2, the temperature drops sharply only in a fraction of a millimeter thick layer, which prevents the casting shell from cracking. Thus setting the intensity

According to the main phases of the casting formation during the heat distribution in the mold, the heat (corresponding to the flow rate of the cooler) allows to improve the quality of castings, increase the resistance of the molds, the latter provides the possibility of increasing the time of continuous operation of the conveyor.

Example (implementation of the proposed method).

0 For a cast-iron conveyor machine with a conveyor length of 42 m and steel molds for the production of castings with a thickness of 50-60 mm (average weight of the casting 13 kg), an upper cooling zone is set 5 with a lower boundary at a distance of 11 m from the casting socks (0.26) L and the upper boundary at a distance of 31 m from the socks (0.74) L. The upper cooling zone is divided into seven sections of a length of 2.85

0 m, on which a collector is mounted to form the air-water mixture supplied from the mold and casting. The collectors are equipped with 10-11 displacement chambers for water and air with slot nozzles

5 types with a reduced hole diameter of 10mm. When the collectors are installed at a height of 370-400 mm above the conveyor surface, the boundaries of the torches of the air-water mixture from the individual nozzles intersect at the surface of the conveyor, and thus, throughout the entire top cooling zone, a continuous water-air curtain is created, watering the molds and castings and baking flow of water along an inclined conveyor (angle of inclination 7 °). Under the conveyor belt; with a tape at a distance of 6 m from the casting nozzles, a 5 m long cooling collector is installed, equipped with 11 nozzles directed at an angle of 45 ° to the lower surface of the mold. thus, the lower cooling is set at 0.26 L. Cooler flow rates in sections are set in accordance with the table.

; Mode I is used when casting pre

individual cast iron, which provides a mass average temperature of castings of 300-450 ° C (under the P-200-250 ° C mode). At a maximum | conveyor speed of 16 m / min.

 Mode II is used for casting mainly cast iron or for overheating of metal over 150 ° C. The seriality of castings in the first mode is 8-9 ladles per share, in the second 7-8.

To remove the crust from non-metallic inclusions and blow off the graphite from the surface of the castings at a distance of 10.8 m from the casting socks, a collector with two nozzles 1 for supplying compressed air to the conveyor is installed; when two nozzles are in operation, the strip width is 0.42 m, one is 0 , 21 m; Two nozzles are turned on with a large number of inclusions or in the implementation of mode II.

 Using the proposed method will allow due to the differentiation of the heat-amp & ode in different parts of the conveyor

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Claims (2)

1. A method of manufacturing ingots on a casting conveyor machine, comprising pouring metal into the molds and supplying a water-borne mixture to the ingots, characterized in that, in order to increase the durability of the publishers, improve the quality of castings and increase productivity, at the initial section of the conveyor of 0.2 -0.3 of its length, lower cooling of the molds is carried out with a water-air mixture, and in the next section, located at a length of 0.7-0.8 length of the conveyor, upper cooling of the molds and ingots is carried out, while the water-air mixture is fed about uschestvl dissolved with differentiated flow of water and air, increasing the flow of water from the boundary of the upper cooling zone to the maximum value and reducing the air flow to a minimum value over a length 0.55-0.65 length of the conveyor. 2. The method according to claim 1, characterized in that in the initial zone of the upper cooling section of 0.005-0.01 the length of the conveyor, compressed air is supplied to the molds and ingots at a speed of 8-10 m / s. Note To the table: collector K 7 is installed at the beginning of the cooling zone, at the end, G is the flow rate of the coolant, m3 / h. 0. 07 qs-ep- i0 L it / s // eb / e / 9o,.