CN113305268B - Casting method of 12-cubic-meter slag ladle - Google Patents

Abstract

The invention provides a casting method of a 12-cubic meter slag ladle, which comprises the following steps: (1) the process design comprises the following steps: adopting a casting scheme with a slag ladle opening facing downwards, wherein a pouring system is a three-layer ceramic pipe pouring channel, a main riser is arranged at the right bottom of the slag ladle, and each of the six anchor feet is provided with a branch riser for simulation pouring to determine each technological parameter; (2) adopting alkali phenolic resin sand molding, adopting split molding for sand mold, and adopting a random tower type sand box for sand box; (3) an embedding technology is adopted to design anti-falling and anti-rotating bag ears; (4) the bottom box is filled with air, and an induced draft fan is adopted for exhausting when pouring; (5) smelting and ladle-to-ladle pouring of molten steel in two furnaces; (6) and (5) cooling and post-treatment. The 12-cubic-meter slag ladle cast by the method reduces the hardness requirement of equipment tools, can reduce the internal defects of products, improves the product quality, meets the use requirement, has the yield up to 99%, greatly reduces the resin sand consumption, saves the production cost and has remarkable economic benefit.

Description

Casting method of 12-cubic-meter slag ladle

Technical Field

The invention belongs to a casting process, and particularly relates to a casting method of a 12-cubic meter slag ladle.

Background

The slag ladle is a necessary container for nonferrous smelting enterprises to hold and transport smelting slag, copper, and slow cooling and crystallizing, the highest temperature of the contained material is 1300 ℃, the slag ladle must meet the technical condition of slow cooling after being filled with slag and transported to a slow cooling field of about 900 ℃, namely, the slag ladle must have higher heat-resistant fatigue performance, meets the working condition of sudden cold and sudden heat, the inner surface of the slag ladle is smooth and flat, the outer wall has no casting defects such as shrinkage porosity, slag inclusion, sand inclusion, cracks, cold insulation, air holes and the like, the slag ladle pressure test is free from leakage and sweat, and the service life is more than or equal to 6 years. The current production situation is that the single weight of a 12 cubic meter slag ladle is about 27 tons, the size is large, and the compactness is difficult to ensure; the electric arc furnace has the advantages of insufficient smelting capability, insufficient pit depth, large sand eating amount of the sand box, serious waste, blasting noise during casting, easy vibration and falling of molding sand, easy falling and rotation of the lugs, large potential safety hazard and the like.

Disclosure of Invention

The invention provides a casting method of a 12-cubic meter slag ladle for solving the problems.

The technical scheme of the invention is realized as follows: a casting method of a 12-cubic meter slag ladle comprises the following steps:

(1) The process design comprises the following steps:

the slag ladle design casting scheme comprises the following steps: the slag ladle opening is downward, the pouring system is a vertical main pouring channel and is connected with three layers of transverse pouring channels, and molten steel is poured into the three layers of transverse pouring channels; a riser system of a heat-insulating heating riser is respectively arranged by combining the middle main riser with six feet;

(2) Manufacturing a tooling model:

the tooling adopts a sand box, the sand box is designed into an eight-section random tower type box, an internal large core is a random hollow sand core, a slag ladle model is manufactured by three bodies of a core head, an upper die body and a lower die body, the bottom layer of the sand box is raised, suspended casting is carried out, and an induced draft fan is used for assisting in exhausting;

(3) Design package ear structure: the bag ear is connected with the bag body by adopting an inlay casting process;

(4) Smelting and pouring molten metal: the capacity of the bottom pouring ladle is enlarged, the electric arc furnace and the intermediate frequency furnace jointly smelt molten steel, then the ladle is transferred to the LF furnace for refining, and the refined molten steel is poured after the components are qualified;

(5) Cooling and post-treatment: determining the heat preservation time of a slag ladle casting, and a slag ladle post-treatment flow and a detection method;

(6) And (3) heat treatment: carrying out a heat treatment process on the casting;

preferably, the method comprises the following steps:

(1) The process design comprises the following steps:

the casting is large in size, the pouring system is a vertical main runner connected with three layers of transverse runners, and bends are added on the vertical main runner and the transverse runner, so that the molten steel is gently flushed and sequentially injected into a cavity; a main riser is arranged at the right bottom of the slag ladle, a heat-insulating heating plate is wound around the main riser, each of six feet of the slag ladle is provided with a heat-insulating heating riser, and repeated analysis, simulation and correction are carried out through magma simulation software to finally determine each technological parameter;

(2) The sand box is designed into eight sections of follow-up tower boxes, the size of the inner cavity of the sand box is reduced by one box according to the shape of a casting, the thickness of a sand layer is 200-250 mm, an inner large core is made into a follow-up hollow sand core, a steel plate is rolled into follow-up core iron, exhaust holes are densely distributed on the side wall, the core iron is wound by a straw curtain, the thickness of the sand layer is about 200mm, and the sand eating amount is reduced; the radial shrinkage 2.15 percent and the axial shrinkage 2 percent are adopted, the radial unilateral +10MM of the inner cavity is used for counteracting the variable after the grass curtain burns, and the grass curtain is divided into a core head, an upper die body and a lower die body to manufacture the models, the bottom box is used for manufacturing a core head sand mold, the core head sand mold needs to be overturned, and all other sections of sand molds do not need to be overturned; after the fourth section of sand box is fully solidified by adopting a split molding method, the fourth section of sand box is connected with a die body model to be hung on a template to reconstruct the rest part, the bottom of the sand box is filled with channel steel, and when casting is carried out, an induced draft fan is used for assisting in exhausting from a hollow large core iron through a bottom sand box;

(3) Design package ear: the embedding technology is adopted, the part of the bag ear extending into the bag body is turned into a trapezoid groove to prevent falling, and the front end is sawed into an inclined plane to prevent rotation;

(4) Pouring: the electric arc furnace and the intermediate frequency furnace melt molten steel, after being combined into a ladle, the ladle is refined in the LF furnace, a bottom pouring type slide plate ladle is adopted, the refined molten steel is poured from a pouring cup, after the casting mould is filled with molten steel, the ladle is quickly moved, slow casting is carried out from a main riser in the middle until the liquid surface of the molten steel is not moved downwards, the riser is filled, the pouring is completed, the pouring temperature is controlled to be 1545-1555 ℃, the pouring time is controlled to be about 3 minutes, and the casting time is controlled to be about 7 minutes;

(5) After the casting is cooled along with the box for more than or equal to 72 hours, unpacking and taking out the casting, gas cutting the casting head, cleaning, polishing and detecting;

(6) And (3) carrying out high-temperature annealing treatment on the whole casting, slowly heating the casting to 650 ℃, preserving heat for 1.5 hours, heating to 900 ℃, preserving heat for 4.5 hours, cooling to below 200 ℃ along with a furnace, and discharging and air cooling.

The beneficial effects of the invention are as follows: the casting method meets the production requirement of a 12-cubic meter slag ladle, and the inner surface of the slag ladle obtained by casting is flat and smooth, and the outer wall has no casting defects such as slag inclusion, sand inclusion, cracks, cold insulation, air holes and the like; no shrinkage porosity or shrinkage cavity; the slag ladle is used for pressure test, and leakage and sweat are avoided; the ear-wrapping device is not fallen off and rotated; the service life is as long as more than 6 years, and the use requirement is met; the existing tooling equipment is fully utilized, so that the investment is reduced; the usage amount of resin sand is greatly reduced; frequent overturning of the sand mould is avoided; optimizing a heat treatment process; the production efficiency is improved, and the cost is saved; the yield of batch production reaches 99 percent, and the economic benefit is obvious. The method has certain adaptability to other large-volume castings or castings with similar shapes.

Drawings

FIG. 1 is a schematic illustration of a slag ladle casting of the present invention;

FIG. 2 is a schematic diagram of a simulated topping system of the present invention;

FIG. 3 is a schematic view of a flask used in the present invention;

FIG. 4 is a schematic view of a large core iron in the flask of the present invention;

FIG. 5 is a schematic view of ear insert casting according to the present invention.

Part description: 1. the heat-insulating heating plate comprises a main riser, 2, a heat-insulating heating plate, 3, a pouring cup, 4, a top box, 5, a seventh box, 6, a sixth box, 7, a fifth box, 8, a fourth box, 9, a hollow sand core, 10, a third box, 11, a second box, 12, a bottom box, 13, a straw curtain, 14, an induced draft fan, 15, a large inner cavity core, 16 and a trunnion.

Detailed Description

For a better understanding and implementation, a casting method of a 12 cubic meter ladle is exemplified below, and the specific steps include:

1. designing and manufacturing:

(1) The casting size is larger, phi 3240mm is 2910mm (see figure 1), the casting system is designed to stably inject molten steel by adopting three layers of transverse pouring channels, a vertical main pouring channel is a phi 120 ceramic pipe, a horizontal transverse pouring channel is a phi 100 ceramic pipe, and elbows are added on the straight pouring channel and the transverse pouring channel, so that the molten steel flushing is smooth; the positive bottom of the slag ladle is provided with a phi 720mm main riser 1 with the height of 1000mm, a heat-insulating heating plate with the thickness of 60mm is wound on the main riser 1 with the height of 2 layers, six feet of the slag ladle are respectively provided with 2 phi 200mm heat-insulating heating risers with the height of 200mm (superposition), and the main riser 1 is repeatedly analyzed, simulated and corrected through magma simulation software to finally determine important parameters such as casting shrinkage rule, pouring channel design, riser design, pouring temperature, pouring time and the like (see figure 2);

(2) The sand box is designed into an eight-section follow-up tower type box, the alkali phenolic resin sand is adopted for molding, the size of the inner cavity of the sand box is reduced case by case according to the shape of a casting, and the thickness of a sand layer is 250mm (see figure 3); the large core inside the sand box is made into a hollow sand core 9 along with the core iron, the steel plate is rolled along with the core iron, the side wall is densely provided with exhaust holes (see figure 4), the core iron is wound by a grass curtain 13, the thickness of the sand layer is about 200mm, and the sand eating amount is reduced; the radial shrinkage 2.15 percent and the axial shrinkage 2 percent are adopted, the radial unilateral +10MM of the inner cavity is used for counteracting the variable after the grass curtain burns, and the grass curtain is divided into a core head, a lower die body and an upper die body to manufacture the models, the bottom box 12 is used for manufacturing a core head sand mould, the core head sand mould needs to be overturned, and the rest sand moulds do not need to be overturned; after the molding of the fourth sand box 8 is fully cured, the fourth sand box 8 is connected with a mold body model to be hung on a template to reconstruct the rest part, so that the problem of shallow pit and insufficient height of a sand mixer head is solved;

(3) The part of the bag ear extending into the bag body is turned into a trapezoid groove to prevent falling, the front end is sawn into an inclined plane to prevent rotation, and an insert casting process is adopted (see figure 5);

(4) The bottom of the sand box is filled with 200 channel steel, and when in pouring, an induced draft fan 14 is used for assisting in exhausting from the hollow large core 9 iron through the bottom sand box, so that the occurrence of blasting phenomenon when large pieces are poured is reduced (see figure 3);

(5) The bottom pouring ladle is heightened by 300mm, the single side of the inner refractory material is thinned by 20mm, and the furnace cover of the LF refining furnace is heightened by 300mm, so that the requirement of 34 tons of molten steel is met; 29 tons of molten steel is melted by an electric arc furnace, 5 tons of molten steel is melted by an intermediate frequency furnace, and the molten steel is mixed into a ladle and then refined by an LF furnace; pouring from a pouring cup, carrying out slow supplementary pouring from a middle main riser, and controlling the pouring temperature to 1550 ℃;

(6) Cooling the casting with the box for 72 hours;

(7) Optimizing a heat treatment process: the slag ladle casting is heated to 650 ℃ at the speed of 80 DEG/h, kept for 1.5 hours, then quickly heated to 900 ℃, kept for 4.5 hours, cooled to below 200 ℃ along with the furnace, and discharged for air cooling.

2. Modeling and core making:

(1) Placing the large core head of the model on a template according to the positioning, placing a chill, placing a bottom sand box, opening a sand mixing machine to perform sand filling, and forming a bottom sand box by using 9 blank spaces in the center of a sand box without sand filling;

(2) After solidification, reversing a bottom box sand mold, placing a model at a stable position, placing a No. 2 sand box, paving a pouring system (four of straight gate mold 120, 120-delta 100 tee joints, runner mold 100 and inner gate mold 100) by using a ceramic pipe, placing a chill, and filling sand to form a No. 2 sand mold;

(3) Sequentially manufacturing No. 3 sand mould, no. 4 sand mould and No. 5 sand mould, wherein the No. 3 sand mould is internally provided with a second layer of pouring system, three pouring gates are arranged, the No. 5 sand mould is internally provided with a third layer of pouring system, and three pouring gates are arranged;

(4) After the No. 5 sand mold is completely solidified, the No. 5 sand mold and the first upper mold body are lifted onto another bottom plate, sand boxes are sequentially placed, and 6# sand mold, 7# sand mold and top sand mold are manufactured, wherein a heat-insulating riser (200, 200 high) is arranged on each of the top sand boxes and six support legs, a middle large riser (720, 1000 high) is formed by winding a heat-insulating plate outside an iron sheet cylinder, and when sand is filled, the middle large riser and a pouring cup of the upper plane are raised by 200MM, and air outlets of 30 are reserved on the six support leg heat-insulating risers.

(5) Spreading and winding the large core iron with a grass curtain, hanging the large core iron to a proper position on a core making template, closing and tightly locking the lower body of the core box, adjusting the position of the large core iron, tamping while filling sand, rapidly positioning the upper body of the core box when the large core iron is full, continuing filling sand and tamping, and hardening the large core;

3. after the sand mold is completely solidified, lifting the top box, the No. 7 sand mold, the No. 6 sand mold and the No. 5 sand mold in sequence, removing the upper mold and the movable block, lifting the No. 4 sand mold, the No. 3 sand mold and the No. 2 sand mold in sequence, removing the lower mold and the movable block, and taking out the core head from the bottom box sand mold;

4. coating and closing: and spraying the paint on the middle large core and each section of sand mould, igniting, baking by a blast lamp, and repeating for four times. Placing the bottom box on four 200 channel steels, filling the bottom box with solid, hoisting the middle large core, aligning the positions, filling gaps with sand, scraping the tops of the balls with sodium silicate sand, and brushing the paint for four times; hoisting a No. 2 sand mould, and positioning the mould assembling; after the lugs are fully baked, the lugs are lifted by iron wires, the iron wires are put into the core heads, and the iron wires are pulled out after the sample plates are detected; then lifting 3# and 4# top box sand mold assembling, locking all the box clamping plates, connecting a dryer to fully bake the cavity, connecting an exhaust tube to a draught fan, and waiting for pouring;

5. smelting and pouring: adopting a bottom pouring type slide plate ladle, melting 29 tons of molten steel by an electric arc furnace, melting 5 tons of molten steel by an intermediate frequency furnace, refining for about 1 hour in an LF furnace after the ladle is closed, discharging after meeting the requirements of components and temperature, feeding aluminum for deoxidization, blowing argon for stirring, and pouring. During casting, an induced draft fan is used for assisting in exhausting from the hollow large core iron through the bottom sand box. Pouring from a pouring cup at 1550 ℃ for about 3 minutes, when molten steel is fast full, rapidly moving a pouring ladle to a middle large riser to start to supplement pouring until the liquid level of the steel is not moved downwards, filling the riser, and after the pouring is completed, covering the riser with a heat preservation agent in time for about 7 minutes;

6. cooling, unpacking and cleaning: cooling the casting with the box for 72 hours, unpacking, and cutting a casting head;

7. post-treatment: polishing, repairing by welding, cleaning the inner and outer surfaces, checking the size of the casting, and checking whether the trunnion and the root of the trunnion are defective or not by using an ultrasonic detector. After completion, the slag ladle is filled with water, and the slag ladle is placed for more than 12 hours to check whether leakage and sweat are generated. And (3) the whole is put into a kiln, subjected to high-temperature annealing heat treatment, cooled to below 200 ℃ along with the furnace, and discharged for air cooling.

After the casting process is used, the casting quality of the 12 cubic meter slag ladle is excellent, the defects are few, and the yield reaches 99 percent.

Claims (1)

1. The casting method of the 12 cubic meter slag ladle is characterized by comprising the following steps of:

(1) The process design comprises the following steps:

the pouring system is a vertical main pouring channel connected with three layers of transverse pouring channels, and bends are added on the vertical pouring channels, so that the molten steel is gently and sequentially poured into a cavity; the main riser with the diameter of 720mm and the height of 1000mm is arranged at the positive bottom of the slag ladle, and the heat-insulating heating plate is wound; 2 heat-preserving exothermic risers with the diameter of 200mm and the height of 200mm are respectively arranged on the six feet of the slag ladle; repeatedly analyzing, simulating and correcting through magma simulation software, and finally determining all process parameters;

(2) The sand box is designed into eight sections of tower-type boxes along with each other, the size of the inner cavity of the sand box is reduced case by case according to the shape of a casting, and the thickness of a sand layer is 200-250 mm; the inner large core is made into a hollow sand core along with the core iron, the steel plate is rolled along with the core iron, the side wall is densely provided with exhaust holes, the core iron is wound by a straw curtain, the thickness of a sand layer is 200mm, and the sand eating amount is reduced; 2.15 percent of radial shrinkage rule and 2 percent of axial shrinkage rule are adopted, and the radial unilateral of the inner cavity is +10MM for counteracting the variable after the grass curtain burns; the method comprises the steps of manufacturing a model by dividing the model into a core print, an upper die body and a lower die body; placing the large core head of the model on a template according to the positioning, placing a chill, placing a bottom sand box, opening a sand mixing machine to perform sand filling, and forming a bottom sand box by using 9 blank spaces in the center of a sand box without sand filling;

the bottom box needs to be turned over, and all other sections of sand molds do not need to be turned over; a split molding method is adopted, namely, after the fourth section of sand box molding is fully solidified, the fourth section of sand box is connected with a mold body model and is lifted to a template to reconstruct the rest part; the bottom of the sand box is filled with channel steel, and when in pouring, an induced draft fan is used for assisting in exhausting from the hollow large core iron through the bottom sand box;

(3) Design package ear: the embedding technology is adopted, and the part of the bag ear extending into the bag body is turned into a trapezoid groove to prevent falling off; the front end is sawed into an inclined plane to prevent rotation;

(4) Pouring: the electric arc furnace and the intermediate frequency furnace melt molten steel, and after being combined into a ladle, the molten steel is refined in an LF furnace; adopting a bottom pouring type slide plate casting ladle; pouring refined molten steel from a pouring cup, quickly moving a casting ladle after the casting mould is filled with molten steel, and slowly compensating pouring from a middle main riser until the liquid level of the molten steel is not moved downwards, filling the riser, and finishing pouring; controlling the casting temperature to 1545-1555 ℃, casting for 3 minutes and compensating for 7 minutes;

(5) After the casting is cooled along with the box for more than or equal to 72 hours, unpacking and taking out the casting, gas cutting a casting head, cleaning and detecting;

(6) The whole casting is annealed at high temperature, the slag ladle casting is slowly heated to 650 ℃ at the speed of 80 ℃/h, the temperature is kept for 1.5 hours, the temperature is further heated to 900 ℃, the temperature is kept for 4.5 hours, and the slag ladle casting is cooled to below 200 ℃ along with the furnace and is discharged for air cooling.