Three-furnace low-pressure casting process for ultra-large component and structure of ultra-large component

Abstract

The invention relates to an ultra-large component three-furnace low-pressure casting process and a structure thereof. The ultra-large component three-furnace low-pressure casting process is characterized in that the specific casting process comprises the following steps of S1, alloy smelting; s2, casting forming; comprising a casting forming mold, a crucible smelting heat preservation furnace, a liquid rising pipe and an air inlet pipe. The three crucible melting and holding furnaces are adopted for melting raw materials for super-long aluminum alloy castings, the sealing effect between the mold and the crucible melting and holding furnaces is guaranteed during passing, molten aluminum liquid is pressed into a cavity through the liquid rising pipe, the aluminum liquid level rises stably, splashing is avoided during mold filling, the pressure is adjustable, riser feeding is not needed, and the production efficiency is improved. The casting quality is good, and the process yield is high; the production efficiency is improved, meanwhile, the situation of wrong boxes is avoided, and the subsequent gap position grinding procedure is omitted.

Description

Technical Field

[0001] The invention relates to the technical field of low-pressure casting of super-large components, and in particular to a three-furnace low-pressure casting process and structure of super-large components. Background Art

[0002] Low-pressure casting is a casting method that uses gas pressure to press metal into the mold and crystallize and solidify under a certain pressure. Since the molten metal rises steadily from bottom to top, there will be no splashing when filling the mold. The atmosphere and pressure are adjustable, and there is no need for riser shrinkage. The casting quality is good and the process yield is high. It is particularly suitable for light alloys such as aluminum and magnesium. It is usually used for small and medium-sized castings.

[0003] With the upgrading of industrial products, many extra-long and extra-heavy (length 4000-5000mm, weight 800-1200kg) aluminum and magnesium alloy castings are designed. They have complex geometric shapes and vary greatly in wall thickness. Because they are used in special occasions, they require high strength and often have high airtightness requirements. Traditional sand gravity casting cannot meet these requirements and low-pressure casting must be used.

[0004] In addition, for castings with a length of more than 2000mm and a single piece weight of more than 550kg, it is necessary to manufacture a larger crucible melting furnace. The horizontal runway is too long, the temperature of the aluminum and magnesium alloys drops significantly during the filling process, oxidation intensifies, and the airtightness and strength of the casting cannot be guaranteed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a three-furnace low-pressure casting process for super-large components and its structure, which can solve the problems of the general over-length rate, the excessive length of the horizontal runway for tank casting, the obvious temperature drop during the filling process of aluminum and magnesium alloys, the aggravated oxidation, and the inability to guarantee the air tightness and strength of the casting.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a three-furnace low-pressure casting process for super-large components, the innovation of which is: the specific casting process is as follows:

[0007] S1: Alloy smelting: three crucible smelting and holding furnaces capable of smelting 600-800kg are selected, and 0.3% of aluminum, titanium and boron by weight is added before smelting; the aluminum ingot is melted in the crucible smelting and holding furnace, and the final temperature of the aluminum liquid is controlled at 710℃-730℃; at the same time, the mold is heated and the temperature of the mold is controlled between 45℃-55℃;

[0008] S2: Casting: Place the casting molding mold above three crucible melting and insulation furnaces, set a riser pipe at the bottom feed port of the casting molding mold to connect with the crucible melting and insulation furnace, and keep the connection sealed; use 0.11Mpa to press the molten aluminum liquid in the crucible melting and insulation furnace into the casting molding mold through the riser pipe, and the filling time is 85s-95s; the pressure holding time is 35min-45min; after completing the pressure holding, release the pressure and ensure unpacking after 3 hours.

[0009] Further, in the alloy smelting, the aluminum ingot is heated to 730°C to form aluminum liquid, stirring and standing are performed alternately and heating is continued; the aluminum liquid temperature is then raised to 760°C-770°C and maintained at a constant temperature, and stirring and standing are continued for 15min-20min; the oxide scale and slag inclusions on the surface of the aluminum liquid in the crucible are skimmed off by a smelting tool, and a small amount of aluminum liquid is scooped into a clean ingot mold with a tool, and cooled for 5min-6min to form a number of prefabricated aluminum ingot samples; then the prefabricated aluminum ingot samples that have been cooled for 5min-6min are put into the aluminum liquid at 760°C-770°C to smelt the aluminum liquid. Rapid cooling; then the temperature of the aluminum liquid is controlled at a casting temperature between 730℃-740℃ by controlling the number of prefabricated aluminum ingot samples; when the temperature of the aluminum liquid drops from 760℃-770℃ to 730℃-740℃, the aluminum liquid is immediately stirred for 5min-6min and the temperature is guaranteed to be between 730℃-740℃; finally, the refining agent is divided into three equal parts and added to the aluminum liquid three times with a time interval of 8min-10min between the three additions of the refining agent; immediately reduce the temperature of the aluminum liquid to between 717℃-723℃ after the third addition of the refining agent; after the addition of the refining agent is completed, the slag is scraped off.

[0010] A three-furnace low-pressure casting structure for ultra-large components, the innovation of which is that it includes a casting forming mold, a crucible melting and holding furnace, a liquid riser and an air inlet pipe;

[0011] The casting forming mold comprises an outer shell and a sand core; the sand core is arranged in the outer shell to form a casting cavity for accommodating aluminum liquid in the outer shell; a plurality of liquid inlets are arranged at the bottom of the outer shell near the two ends and in the length direction of the outer shell; the liquid inlet below the outer shell is connected in parallel to a liquid inlet pipe;

[0012] There are three crucible melting and holding furnaces, and the crucible melting and holding furnaces are arranged below the casting forming mold;

[0013] There are three liquid riser pipes which are correspondingly connected to the liquid inlet pipes below the outer shell, and the bottom ends of the liquid riser pipes extend into the crucible smelting and insulation furnace.

[0014] Furthermore, a pad is provided between the outer shell of the casting forming mold and the crucible melting and insulation furnace, and the bottom end of the pad is tightly sealed against the upper surface of the crucible melting and insulation furnace; a through hole is opened on the pad to accommodate the passage of an air inlet pipe, and the air inlet pipe extends through the through hole of the pad to the crucible melting and insulation furnace, and the aluminum pressure of the crucible melting and insulation furnace is hydraulically pressed into the cavity of the casting forming mold by pressurizing the air inlet pipe.

[0015] The advantages of the present invention are:

[0016] 1) In the present invention, three crucible melting and holding furnaces are used to melt the raw materials for the super-long aluminum alloy castings, and the sealing effect between the mold and the crucible melting and holding furnace is ensured. The molten aluminum is pressed into the mold cavity through the riser, and the aluminum liquid level rises steadily. No splashing occurs during filling. The pressure is adjustable, and no riser shrinkage is required. The casting quality is good and the process yield is high. The production efficiency is improved, and the misalignment of the box is avoided, and the subsequent gap position grinding process is omitted. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 The present invention is a three-furnace low-pressure casting process flow chart of a super-large component.

[0019] Figure 2 This is a diagram of a three-furnace low-pressure casting device for super-large components according to the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] like Figure 1 The three-furnace low-pressure casting process for a super-large component is shown in the figure. The specific casting process is as follows:

[0023] S1: Alloy smelting: three crucible smelting and holding furnaces capable of smelting 600-800kg are selected, and 0.3% of aluminum, titanium and boron by weight is added before smelting; the aluminum ingot is melted in the crucible smelting and holding furnace, and the final temperature of the aluminum liquid is controlled at 710℃-730℃; at the same time, the mold is heated and the temperature of the mold is controlled between 45℃-55℃;

[0024] S2: Casting: Place the casting molding mold above three crucible melting and insulation furnaces, set a riser pipe at the bottom feed port of the casting molding mold to connect with the crucible melting and insulation furnace, and keep the connection sealed; use 0.11Mpa to press the molten aluminum liquid in the crucible melting and insulation furnace into the casting molding mold through the riser pipe, and the filling time is 85s-95s; the pressure holding time is 35min-45min; after completing the pressure holding, release the pressure and ensure unpacking after 3 hours.

[0025] S1: During alloy smelting: heat the aluminum ingot to 730℃ to form aluminum liquid, start stirring and standing alternately and continue heating; then raise the aluminum liquid temperature to 760℃-770℃ and keep it at a constant temperature, continue stirring and standing alternately for 15min-20min; then use a smelting tool to skim off the oxide scale and slag inclusions on the surface of the aluminum liquid in the crucible, use a tool to scoop a small amount of aluminum liquid into a clean ingot mold, cool it for 5min-6min, and form several prefabricated aluminum ingot samples; then put the several prefabricated aluminum ingot samples that have been cooled for 5min-6min into the aluminum liquid at 760℃-770℃ to rapidly cool the aluminum liquid; Then, the temperature of the aluminum liquid is controlled at a casting temperature between 730℃-740℃ by controlling the number of prefabricated aluminum ingot samples; when the temperature of the aluminum liquid drops from 760℃-770℃ to 730℃-740℃, the aluminum liquid is immediately stirred for 5min-6min and the temperature is guaranteed to be between 730℃-740℃; finally, the refining agent is divided into three equal parts and added to the aluminum liquid three times with a time interval of 8min-10min between the three additions of the refining agent; immediately after the third addition of the refining agent, the temperature of the aluminum liquid is lowered to between 717℃-723℃; after the addition of the refining agent, the slag is scraped off.

[0026] like Figure 2 The three-furnace low-pressure casting structure of a super-large component shown in the figure comprises a casting forming mold 1, a crucible melting and holding furnace 2, a liquid riser 3 and an air inlet pipe 4.

[0027] The casting forming mold 1 includes an outer shell 11 and a sand core 12; the sand core 12 is arranged in the outer shell 11, and a casting cavity for accommodating aluminum liquid is formed in the outer shell 11; a plurality of liquid inlets are arranged at the bottom of the outer shell 11 near the two ends and in the length direction of the outer shell 11; the liquid inlet below the outer shell 11 is connected in parallel to a liquid inlet pipe 5.

[0028] There are three crucible melting and holding furnaces 2 , which are arranged below the casting forming mold 1 .

[0029] There are three riser pipes 3 which are correspondingly connected to the liquid inlet pipes below the outer shell 11 , and the bottom ends of the riser pipes 3 extend into the crucible smelting and holding furnace 2 .

[0030] A pad is arranged between the outer shell 11 of the casting forming mold 1 and the crucible melting and insulation furnace 3, and the bottom end of the pad is tightly sealed against the upper surface of the crucible melting and insulation furnace; a through hole is opened on the pad to accommodate the passage of the air inlet pipe, and the air inlet pipe 4 extends through the through hole of the pad to the crucible melting and insulation furnace 2, and the aluminum pressure of the crucible melting and insulation furnace 2 is hydraulically pressed into the cavity of the casting forming mold 1 by pressurizing the air inlet pipe 4.

[0031] Those skilled in the art should understand that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements shall all fall within the scope of the present invention claimed for protection.

Claims

1. A three-furnace low-pressure casting process for ultra-large components, characterized in that: The specific casting process is as follows: S1: Alloy smelting: three crucible smelting and holding furnaces capable of smelting 600-800kg are selected, and 0.3% of aluminum, titanium and boron by weight is added before smelting; the aluminum ingot is melted in the crucible smelting and holding furnace, and the final temperature of the aluminum liquid is controlled at 710℃-730℃; at the same time, the mold is heated and the temperature of the mold is controlled between 45℃-55℃; S2: Casting: Place the casting molding mold above three crucible melting and insulation furnaces, set a riser pipe at the bottom feed port of the casting molding mold to connect with the crucible melting and insulation furnace, and keep the connection sealed; use 0.11Mpa to press the molten aluminum liquid in the crucible melting and insulation furnace into the casting molding mold through the riser pipe, and the filling time is 85s-95s; the pressure holding time is 35min-45min; after completing the pressure holding, release the pressure and ensure unpacking after 3 hours.

2. The three-furnace low-pressure casting process for super-large components according to claim 1 is characterized in that: S1: During alloy smelting: the aluminum ingot is heated to 730°C to form aluminum liquid, stirring and standing are performed alternately and heating is continued; then the aluminum liquid temperature is raised to 760°C-770°C and maintained at a constant temperature, stirring and standing are continued until the alternation is performed for 15min-20min; then the oxide scale and slag inclusions on the surface of the aluminum liquid in the crucible are skimmed off by a smelting tool, a small amount of aluminum liquid is scooped into a clean ingot mold with a tool, and cooled for 5min-6min to form a number of prefabricated aluminum ingot samples; then the prefabricated aluminum ingot samples that have been cooled for 5min-6min are put into the aluminum liquid at 760°C-770°C to rapidly cool the aluminum liquid ; Then, the temperature of the aluminum liquid is controlled at a casting temperature between 730℃-740℃ by controlling the number of prefabricated aluminum ingot samples; when the temperature of the aluminum liquid drops from 760℃-770℃ to 730℃-740℃, the aluminum liquid is immediately stirred for 5min-6min and the temperature is guaranteed to be between 730℃-740℃; finally, the refining agent is divided into three equal parts and added to the aluminum liquid three times with a time interval of 8min-10min between the three additions of the refining agent; immediately after the third addition of the refining agent, the temperature of the aluminum liquid is lowered to between 717℃-723℃; after the addition of the refining agent, the slag is scraped off.

3. A three-furnace low-pressure casting structure for ultra-large components, characterized in that: It includes a casting forming mold, a crucible melting and holding furnace, a liquid riser and an air inlet pipe; The casting forming mold comprises an outer shell and a sand core; the sand core is arranged in the outer shell to form a casting cavity for accommodating aluminum liquid in the outer shell; a plurality of liquid inlets are arranged at the bottom of the outer shell near the two ends and in the length direction of the outer shell; the liquid inlet below the outer shell is connected in parallel to a liquid inlet pipe; There are three crucible melting and holding furnaces, and the crucible melting and holding furnaces are arranged below the casting forming mold; There are three liquid riser pipes which are correspondingly connected to the liquid inlet pipes below the outer shell, and the bottom ends of the liquid riser pipes extend into the crucible smelting and insulation furnace.

4. According to claim 3, a three-furnace low-pressure casting structure for super-large components is characterized in that: A pad is arranged between the outer shell of the casting forming mold and the crucible melting and insulation furnace, and the bottom end of the pad is tightly sealed against the upper surface of the crucible melting and insulation furnace; a through hole for accommodating an air inlet pipe is opened on the pad, and the air inlet pipe extends through the through hole of the pad to the crucible melting and insulation furnace, and the aluminum pressure of the crucible melting and insulation furnace is hydraulically pressed into the cavity of the casting forming mold by pressurizing the air inlet pipe.

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