RU2288067C2 - Billet casting method - Google Patents

Abstract

FIELD: metallurgy, namely production of measured billets of metals and alloys.

SUBSTANCE: method comprises step of feeding melt metal into water cooled casting mold; after forming on inner surface of casting mold solidified metal skin in the form of sleeve of uniform thickness extracting said skin together with melt metal. Time period for forming such skin depends upon type of cast metal. Skin extraction speed is in range 0.1 - 1.2 m/s. Skin with melt metal is immersed into bath with water at rate 0.03 - 0.3 m/s by depth consisting of 0.65 -0.85 of skin height. Uniform thickness of solidified skin of metal lowers thermal stresses of billet.

EFFECT: increased crystallization rate of billet, enhanced efficiency of method, high quality of billets of different metals and alloys.

4 cl, 4 dwg, 3 ex

Description

The invention relates to metallurgy and is intended to obtain dimensional blanks from metals and alloys.

A known method that combines casting and subsequent solidification (Belenovsky IP and other Technology for the production of cast iron shots. Foundry, 1951, No. 8, p.6). A known method that combines casting and subsequent solidification (Russian Patent No. 2063305, IPC B 22 F 9/05). In these methods, the molten metal is divided into droplets during casting and cooled directly in a bath of water. These methods are mainly used to obtain steel and cast iron shots.

A known method that combines the casting and solidification of a liquid billet (Schwarzmeier B. Continuous casting. Moscow, Publishing house of literature on ferrous and non-ferrous metallurgy, 1962, pp. 106-108, Fig. 32). The method includes: feeding liquid metal into a metal water-cooled mold, forming a crust on its inner surface, gradually removing it down with the liquid metal, and simultaneously immersing them in a bath of water. Combined extraction and immersion leads to the fact that the heat sink from the lower part of the workpiece significantly exceeds the heat sink from its upper part. A significant difference in height of the crust of the cast metal is associated with this, which causes large thermal stresses. This leads to rupture of the crust and a violation of the stability of the casting process. Due to the high thermal stresses in the crust, metal casting is carried out at a relatively low speed [3], which reduces the productivity of the casting process and the quality of the workpiece. High thermal stresses associated with a significant difference in the crust significantly narrow the scope of this method. It is mainly used to produce blanks from aluminum alloys.

The closest in technical essence is the "Process of the production of ingots and castings", including pouring liquid metal into a mold, forming a hardening metal crust on its inner surface, removing the crust with liquid metal from the mold and cooling (EP 0183679 A2, IPC ⁷ B 22 D 7 / 00, 7/08).

The disadvantages include the fact that the method is mainly intended for casting refractory metals and alloys and the low productivity of the casting process, since the extraction of the workpiece takes place in two stages after its complete solidification in the mold.

The technical problem to be solved by the claimed casting method is aimed at increasing the productivity of the casting process, improving the quality of the workpiece and expanding the scope of the method for producing dimensional blanks from various metals and alloys. This object is achieved by the fact that in the inventive casting method, comprising supplying liquid metal to a metal water-cooled mold, forming a crust in the form of a cup on its inner surface, removing it together with the liquid metal from the mold and immersing it in a bath with water, the crust is formed into water-cooled form with a uniform thickness over time depending on the type of metal or alloy, removing the crust from the mold is carried out at a speed of 0.1-1.2 m / s and immersed in a bath with water at a speed of 0.03-0.3 m / s to a depth of 0.65-0.8 5 peel heights; when casting billets of steel, cast iron, zinc and its alloys, aluminum and its alloys, alloys based on tin and lead, the crust is formed within 5-30 s; when casting billets of copper and copper alloys, the crust is formed within 3-15 s; the mold can also be made in the form of drop segments.

The drawing shows a casting scheme of blanks,

where a is the filling of the form;

b - formation of a crust;

in - extraction of a glass;

g - tempering a glass with liquid metal,

where 1 is the filling device, 2 is the stationary part of the mold, 3 is the movable part of the mold, 4 is the hardened crust (glass), 5 is liquid metal, 6 is a bath of water.

Obtaining cast billets is carried out in the following way. Using a casting device 1, a metal water-cooled casting mold consisting of a stationary 2 and a movable 3 parts is filled with a melt. After reaching a predetermined level, the liquid metal is held for a specified time to form a crust (cup) 4. Next, using a movable casting mold 3, the cup is removed together with the liquid metal 5 and immersed in a bath of water 6. The uniformity of the thickness of the cup rind significantly reduces thermal stress during the solidification of the workpiece, increases its crystallization rate, the quality of the workpieces and the performance of the casting process, since it will be determined mainly by the duration of the formation of metal ki.

Removing the glass at a speed of more than 1.2 m / s leads to the splashing of the liquid metal and the destruction of the crust. Removing the glass at a speed of less than 0.1 m / s increases the difference in the crust, which affects the quality of the casting. When a glass with liquid metal is immersed in a bath with water at a speed of less than 0.03 m / s, the crystallization rate of the workpiece significantly decreases and, accordingly, its quality deteriorates. When a glass with liquid metal is immersed in a bath with water at a speed of more than 0.3 m / s, the shrinkage porosity in the workpiece increases, resulting in castings being defective. When a glass with liquid metal is immersed in a bath of water to a depth less than 0.65 of its height, the yield of metal is significantly reduced. When a glass with liquid metal is immersed in a bath of water to a depth of more than 0.85 of its height, shrink shells appear in the billet, which leads to casting marriage. The formation of a crust for steel, cast iron, zinc and its alloys, aluminum and its alloys, alloys based on tin and lead in less than 5 s leads to the melting of the glass with liquid metal and the stability of the casting process. Over a period of more than 30 s, a crust with a thickness of more than 10-15 mm is formed, which reduces the rate of solidification of the workpieces and affects their quality. The formation of a crust for copper and its alloys in less than 3 s leads to the melting of the glass with liquid metal and its pouring. Over a period of more than 15 s, a crust of more than 10-15 mm is formed, which reduces the rate of solidification of the workpieces and affects their quality.

Example 1

Cylindrical billets were cast with a diameter of 45 mm and a height of 180 mm from aluminum, silumins AK12 and AK18, zinc, TsAM10-5 alloy, B-83 and B-S babbits, steel 45, and VCh60 cast iron. The liquid metal was kept in a water-cooled copper form for 6-8 s, after which the glass with the liquid metal was removed at a speed of 0.5 m / s. After 1.5-2 s, a glass with liquid metal was immersed in a bath with water at a speed of 0.1 m / s to a depth of 0.75 the height of the glass. As a result, blanks without defects with high physical and mechanical properties were obtained. The dispersion of phase components and grains was 5-10 times higher than that of similar continuously cast billets.

Example 2

Billets with a diameter of 45 mm and a height of 180 mm were cast from bronzes BrAZH9-4 and Br.O3Ts7S5N. The liquid metal was kept in a copper water-cooled form for 4 s, after which the glass with liquid metal was removed at a speed of 0.5 m / s. After 1.5-2 s, a glass with liquid metal was immersed in a bath with water at a speed of 0.1 m / s to a depth of 0.75 the height of the glass. As a result, blanks without defects with high physical and mechanical properties were obtained. The dispersion of phase components and grains was 4-6 times higher than that of similar continuously cast billets.

Example 3

Billets were cast with a diameter of 115 mm and a height of 180 mm from silumins AK12 and AK18. The liquid metal was kept in a copper water-cooled form for 15 s, after which the glass with the liquid metal was removed at a speed of 0.5 m / s. After 2 sec. a glass with liquid metal was immersed in a bath with water at a speed of 0.05 m / s to a depth of 0.75 the height of the glass. As a result, blanks without defects with high physical and mechanical properties were obtained. The dispersion of crystals of primary and eutectic silicon was 4-10 times higher than that of similar continuously cast billets.

Claims (4)

1. A method of casting billets, including feeding liquid metal into a metal mold, forming a hardened metal crust on its inner surface in the form of a glass, removing it together with the liquid metal from the mold and cooling, characterized in that the hardened crust is formed in a water-cooled mold with uniform thickness during the time, depending on the type of metal or alloy, the extraction of the crust from the mold is carried out at a speed of 0.1-1.2 m / s, and the cooling of the crust with liquid metal is carried out by immersion in a bath with water at a speed of 0 , 03-0.3 m / s to a depth equal to 0.65-0.85 of the height of the crust. 2. The method according to claim 1, characterized in that the mold is made in the form of expanding segments. 3. The method according to claim 1, characterized in that when casting billets of steel, cast iron, zinc and its alloys, aluminum and its alloys, tin and lead based alloys, the crust is formed within 5-30 s. 4. The method according to claim 1, characterized in that when casting billets of copper and copper alloys, the crust is formed within 3-15 seconds.