Pouring production process for high-precision steel casting

Abstract

The invention belongs to the technical field of casting, and particularly relates to a high-precision steel casting pouring production process which comprises the following steps of modeling and core making, box closing, steel making, pouring, cooling, box opening and sand shakeout, sand cleaning and steel casting annealing heat treatment. Then the molten steel in the pouring ladle is poured into a casting mold, and the molten steel is prevented from being oxidized in a nitrogen protection mode in the pouring ladle conveying and pouring process; nitrogen is introduced into a pouring ladle to form a protective atmosphere, oxygen on the upper surface of molten steel is discharged, the oxygen content in the molten steel is reduced, the problem that the surface of a casting is rough due to the fact that the molten steel is oxidized is solved, the situation that oxide in the molten steel reacts with oxide in a casting mold to generate ferrous silicate is reduced, the casting mold is prevented from being corroded by the ferrous silicate, and the casting quality is improved. The service life of the casting mould is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of casting, and in particular relates to a high-precision casting production process for steel parts. Background Art

[0002] Steel castings are parts made of cast steel, with properties similar to cast iron but greater strength. Most metal components for valves and pumps are cast from a blank before finishing. Casting involves pouring liquid metal from a ladle into a casting cavity tailored to the part's shape, then allowing it to cool and solidify to create the final part or blank.

[0003] In the existing casting of steel castings, since the ladle is open, the molten steel in the ladle is prone to generate oxides. The molten steel oxides react with the oxides in the mold to form compounds such as ferrous silicate. The melting point of ferrous silicate is lower than that of molten steel, and its high fluidity makes it easy to flow rapidly in the mold and corrode the mold. As a result, the surface roughness of the casting formed after the molten steel cools from the corroded inner wall of the mold is large, which is not conducive to subsequent processing. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned technical problems and provide a high-precision steel casting production process, thereby improving the quality of the castings and extending the service life of the mold.

[0005] In view of this, the present invention provides a high-precision steel casting casting production process, comprising the following steps: S1, Molding and Core Making: Preparation of sand molds and sand cores to form castings; S2, box assembly: assemble the prepared sand mold and sand core, prepare for pouring, and place the inner chiller and core support; S3, steelmaking: steel and alloy materials are melted, refined, and chemically modified by removing harmful elements, removing inclusions, deoxidizing, and degassing to obtain molten steel; S4, pouring: The refined molten steel is transported from the steelmaking furnace to the pouring position using a pouring ladle, and then the molten steel in the pouring ladle is poured into the casting mold. Nitrogen protection is used during the transportation and pouring process to prevent the molten steel from oxidation; S5, cooling: After pouring is completed, the molten steel is gradually cooled in the mold by natural cooling; S6, unpacking and sand removal: After cooling, open the mold and take out the casting. Then, remove the residual molding sand on the surface and inner cavity of the casting, and remove the core bone and the cold iron on the surface of the casting. S7, annealing heat treatment of steel castings: heat the steel castings to 20-30℃ above AC3, keep warm and then cool.

[0006] In this technical solution, after the molten steel is loaded into the pouring ladle, the ladle needs to go through two steps of transfer and pouring to complete the pouring of the molten steel into the casting mold. After the molten steel is loaded into the pouring ladle, nitrogen is introduced into the ladle to form a protective atmosphere, which discharges oxygen on the surface of the molten steel, reduces the oxygen content in the molten steel, improves the problem of rough surface of the casting caused by oxidation of the molten steel, and reduces the reaction of oxides in the molten steel with oxides in the mold to generate ferrous silicate, thereby avoiding corrosion of the mold by ferrous silicate, improving the quality of the casting, and extending the service life of the mold.

[0007] Furthermore, the box closing work is carried out according to the following steps: S2.1: Check, clean and repair all sand molds and sand cores, and check the drying degree of the sand cores and whether the ventilation channels are unobstructed; S2.2: Load the sand core into the sand mold to ensure the wall thickness of the casting, fix the sand core, exhaust the core head and fill the gaps at the joints; S2.3: Remove loose sand from the mold and place a circle of mud strips or asbestos rope on the parting surface along the periphery of the cavity to ensure that the parting surface is tightly fitted after the mold is closed to prevent liquid metal from flowing out of the gap between the parting surfaces. S2.4: Place the weight or secure the mold with bolts or metal clips, and place the pouring cup and riser ring.

[0008] Furthermore, the pouring ladle comprises: A barrel body, the top of which is open and is used to contain molten steel. The barrel body is provided with a spout for the molten steel to flow out; The barrel cover is used to cover the opening above the barrel body, and the barrel cover is equipped with an automatic flip-up structure; A nitrogen introduction mechanism is used to introduce nitrogen into the barrel cover.

[0009] Furthermore, the nitrogen introduction mechanism includes: An air intake pipe, wherein the air inlet of the air intake pipe is exposed outside the barrel cover, and the air outlet of the air intake pipe is located inside the barrel cover; An air supply source is connected to the air inlet of the air inlet pipe, and compressed nitrogen is stored in the air supply source.

[0010] Furthermore, the air intake pipe includes: a first pipe, wherein one end of the first pipe is exposed outside the barrel cover and serves as an air inlet, and the other end of the first pipe gradually decreases in diameter and forms a cone; a second pipe, wherein the inner diameter of the second pipe is the same as the outer diameter of the first pipe, the second pipe and the first pipe are coaxial, the second pipe is provided with the above-mentioned air outlet, and the end of the second pipe away from the first pipe is provided with an exhaust port, and when the second pipe is sleeved on the tapered end of the first pipe, it is in the intake state of the intake pipe, and when the second pipe is away from the tapered end of the first pipe and forms an exhaust gap with the tapered end, it is in the exhaust state of the intake pipe; The switching structure is used to switch the air intake pipe between an intake state and an exhaust state. When the air intake pipe is in the exhaust state, the air outlet on the second pipe is blocked by the closing structure.

[0011] In the present technical solution, after the barrel is filled with molten steel, the barrel cover is put on, and then the air is introduced from the air inlet of the first pipe. At this time, the space between the barrel cover and the liquid level of the molten steel in the barrel is full of air. The state of the air inlet pipe is switched to the exhaust state by switching the structure, so that the second pipe is away from the tapered end of the first pipe and forms an exhaust gap with the tapered end. Since the flow rate of the nitrogen gas entering the first pipe becomes faster at the tapered end, the air pressure here is low. The air in the space between the barrel cover and the liquid level of the molten steel in the barrel will flow into the second pipe from the exhaust gap and be discharged from the exhaust port, so that the air can be discharged quickly. Then, when the predetermined time is reached, the air is basically discharged. The state of the air inlet pipe is switched to the exhaust state by switching the structure. In the air intake state, the second pipe is sleeved on the tapered end of the first pipe. At this time, the sealing structure for the air outlet on the second pipe is released, allowing nitrogen to enter the air intake pipe and then be discharged from the air outlet into the space between the barrel cover and the molten steel liquid level in the barrel body. By introducing nitrogen into the casting ladle, a protective atmosphere is formed, and oxygen on the surface of the molten steel is discharged, thereby reducing the oxygen content in the molten steel, improving the problem of rough surface of the casting caused by oxidation of the molten steel, and reducing the reaction between oxides in the molten steel and oxides in the mold to generate ferrous silicate, thereby avoiding ferrous silicate from corroding the mold, improving the quality of the casting, and extending the service life of the mold. By switching between the two states of the air intake pipe, the operation and structure are relatively simple.

[0012] Furthermore, the first pipe is also provided with an air outlet.

[0013] In this technical solution, in the exhaust state, nitrogen can be introduced into the space between the barrel cover and the molten steel level in the barrel body through the outlet of the first pipe to prevent the air pressure from being too low.

[0014] Furthermore, a detachable closing cover is provided at the exhaust port.

[0015] In this technical solution, when the air intake pipe is switched to the air intake state, the sealing cover is closed to prevent nitrogen from overflowing.

[0016] Furthermore, the switching mechanism includes an external thread arranged on the outside of the second pipe and a threaded hole opened on the barrel cover, and the second pipe is spirally connected to the barrel cover.

[0017] In this technical solution, when switching is required, the second pipe is rotated to move the second pipe forward and backward in the threaded hole to approach or move away from the first pipe.

[0018] Furthermore, the closed structure includes a third pipe, which is rotatably arranged in the second pipe. The third pipe is provided with a switching hole that matches the air outlet on the second pipe. When the switching hole and the air outlet are staggered, the air outlet is in a blocked state.

[0019] Furthermore, the barrel cover has rotating shafts extending from both ends, which are rotatably arranged on a mounting frame outside the barrel body. The automatic lid-turning structure includes: A gear, the gear being coaxially fixedly disposed on the rotating shaft; a rack meshing with the gear; The flip cover oil cylinder is fixedly arranged on the mounting frame, and the output end of the flip cover oil cylinder is connected to the rack for sliding with the rack.

[0020] The beneficial effects of the present invention are: 1. After the molten steel is loaded into the pouring ladle, the ladle needs to go through two steps of transfer and dumping to complete the pouring of the molten steel into the mold. After the molten steel is loaded into the pouring ladle, nitrogen is introduced into the ladle to form a protective atmosphere, which discharges oxygen on the surface of the molten steel, reduces the oxygen content in the molten steel, improves the problem of rough surface of the casting caused by oxidation of the molten steel, and reduces the reaction of oxides in the molten steel with oxides in the mold to generate ferrous silicate, avoids ferrous silicate corrosion of the mold, improves the quality of the casting, and extends the service life of the mold.

[0021] 2. By switching between two states of the intake pipe, the operation and structure are relatively simple.

[0022] 3. In the exhaust state, nitrogen can be introduced into the space between the barrel cover and the molten steel level in the barrel body through the outlet of the first pipe to prevent the air pressure from being too low. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional picture of the pouring ladle; Figure 2 This is a three-dimensional image of the pouring ladle with the lid opened; Figure 3 This is a half-section view of the air intake pipe of the barrel cover in the exhaust state; Figure 4 This is a half-section view of the air intake pipe of the barrel cover in the air intake state; Figure 5 This is an exploded view of the second and third pipelines.

[0024] The marks in the figure are: 1. Barrel body; 2. Barrel spout; 3. Barrel cover; 4. Air inlet pipe; 5. Air inlet; 6. Air outlet; 7. First pipe; 8. Tapered end; 9. Second pipe; 10. Exhaust port; 11. Closing cover; 12. External thread; 13. Threaded hole; 14. Third pipe; 15. Switching hole; 16. Rotating shaft; 17. Gear; 18. Rack; 19. Flip-top cylinder. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0026] In the description of this application, it should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0027] It should be noted that the terms "first," "second," etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way are interchangeable where appropriate, so that the embodiments of this application can be implemented in an order other than those illustrated or described herein, and that the objects distinguished by "first," "second," etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0028] It should be noted that, in the description of this application, the directions or positional relationships indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise specified, these directional terms do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of this application; the directional terms "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0029] It should be noted that, in the present application, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0030] Example 1 A high-precision steel casting production process comprises the following steps: S1, Molding and Core Making: Preparation of sand molds and sand cores to form castings; S2, box assembly: assemble the prepared sand mold and sand core, prepare for pouring, and place the inner chiller and core support; S3, steelmaking: steel and alloy materials are melted, refined, and chemically modified by removing harmful elements, removing inclusions, deoxidizing, and degassing to obtain molten steel; S4, pouring: The refined molten steel is transported from the steelmaking furnace to the pouring position using a pouring ladle, and then the molten steel in the pouring ladle is poured into the casting mold. Nitrogen protection is used during the transportation and pouring process to prevent the molten steel from oxidation; S5, cooling: After pouring is completed, the molten steel is gradually cooled in the mold by natural cooling; S6, unpacking and sand removal: After cooling, open the mold and take out the casting. Then, remove the residual molding sand on the surface and inner cavity of the casting, and remove the core bone and the cold iron on the surface of the casting. S7, annealing heat treatment of steel castings: heat the steel castings to 20-30℃ above AC3, keep warm and then cool.

[0031] After the molten steel is loaded into the pouring ladle, the ladle needs to go through two steps of transfer and dumping to complete the pouring of the molten steel into the mold. After the molten steel is loaded into the pouring ladle, nitrogen is introduced into the ladle to form a protective atmosphere, which discharges oxygen on the surface of the molten steel, reduces the oxygen content in the molten steel, improves the problem of rough surface of the casting caused by oxidation of the molten steel, and reduces the reaction of oxides in the molten steel with oxides in the mold to generate ferrous silicate, avoids ferrous silicate from corroding the mold, improves the quality of the casting, and extends the service life of the mold.

[0032] The box closing work is carried out according to the following steps: S2.1: Check, clean and repair all sand molds and sand cores, and check the drying degree of the sand cores and whether the ventilation channels are unobstructed; S2.2: Load the sand core into the sand mold to ensure the wall thickness of the casting, fix the sand core, exhaust the core head and fill the gaps at the joints; S2.3: Remove loose sand from the mold and place a circle of mud strips or asbestos rope on the parting surface along the periphery of the cavity to ensure that the parting surface is tightly fitted after the mold is closed to prevent liquid metal from flowing out of the gap between the parting surfaces. S2.4: Place the weight or secure the mold with bolts or metal clips, and place the pouring cup and riser ring.

[0033] Example 2 like Figure 1-5 As shown, the pouring bag includes: A barrel body 1 is provided with an opening at the top thereof for containing molten steel and a spout 2 for outflowing the molten steel; The barrel cover 3 is used to cover the opening above the barrel body 1, and the barrel cover 3 is equipped with an automatic flip-up structure; The nitrogen introduction mechanism is used to introduce nitrogen into the barrel cover 3.

[0034] The nitrogen introduction mechanism comprises: an air inlet pipe 4, wherein an air inlet 5 of the air inlet pipe 4 is exposed outside the barrel cover 3, and an air outlet 6 of the air inlet pipe 4 is located inside the barrel cover 3; An air supply source is connected to the air inlet 5 of the air inlet pipe 4, and compressed nitrogen is stored in the air supply source.

[0035] The air intake pipe 4 includes: a first pipe 7, one end of which is exposed outside the barrel cover 3 as the air inlet 5, and the other end of which has a gradually decreasing diameter and a tapered shape; a second pipe 9, wherein the inner diameter of the second pipe 9 is the same as the outer diameter of the first pipe 7, the second pipe 9 and the first pipe 7 are coaxially arranged, the second pipe 9 is provided with the aforementioned air outlet 6, and the end of the second pipe 9 away from the first pipe 7 is provided with an exhaust port 10. When the second pipe 9 is sleeved on the tapered end 8 of the first pipe 7, the air intake pipe 4 is in an intake state. When the second pipe 9 is away from the tapered end 8 of the first pipe 7 and an exhaust gap is formed therebetween, the air intake pipe 4 is in an exhaust state. The switching structure is used to switch the air intake pipe 4 between an intake state and an exhaust state. When the air intake pipe 4 is in the exhaust state, the air outlet 6 on the second pipe 9 is blocked by the closing structure.

[0036] After the barrel body 1 is filled with molten steel, the barrel cover 3 is covered, and then the air is introduced from the air inlet 5 of the first pipe 7. At this time, the space between the barrel cover 3 and the liquid level of the molten steel in the barrel body 1 is full of air. The state of the air inlet pipe 4 is switched to the exhaust state by switching the structure, so that the second pipe 9 is away from the tapered end 8 of the first pipe 7 and forms an exhaust gap with the tapered end 8. Since the flow rate of the nitrogen gas entering the first pipe 7 becomes faster at the tapered end 8, the air pressure here is low. The air in the space between the barrel cover 3 and the liquid level of the molten steel in the barrel body 1 will flow into the second pipe 9 from the exhaust gap and be discharged from the exhaust port 10, which can quickly exhaust the air. After the predetermined time is reached, the air is basically exhausted. The state of the air inlet pipe 4 is switched to the exhaust state by switching the structure. In the air intake state, the second pipe 9 is sleeved on the tapered end 8 of the first pipe 7. At this time, the sealing structure of the air outlet 6 on the second pipe 9 is released, and the nitrogen enters the air intake pipe 4 and is discharged from the air outlet 6 into the space between the barrel cover 3 and the molten steel liquid level in the barrel body 1. By introducing nitrogen into the casting ladle, a protective atmosphere is formed, and the oxygen on the surface of the molten steel is discharged, thereby reducing the oxygen content in the molten steel, improving the problem of rough surface of the casting caused by oxidation of the molten steel, and reducing the reaction of oxides in the molten steel with oxides in the mold to generate ferrous silicate, thereby avoiding ferrous silicate from corroding the mold, improving the quality of the casting, and extending the service life of the mold. By switching between the two states of the air intake pipe 4, the operation and structure are relatively simple.

[0037] The first pipe 7 is also provided with an air outlet 6. In the exhaust state, nitrogen can be introduced into the space between the barrel cover 3 and the molten steel level in the barrel body 1 through the air outlet 6 of the first pipe 7 to prevent the air pressure from being too low.

[0038] The exhaust port 10 is provided with a detachable closing cover 11. When the air intake pipe 4 is switched to the air intake state, the closing cover 11 is closed to prevent nitrogen from overflowing.

[0039] The switching mechanism includes an external thread 12 provided on the outside of the second pipe 9 and a threaded hole 13 provided on the barrel cover 3. The second pipe 9 is screwed to the barrel cover 3. When switching is required, the second pipe 9 is rotated so that the second pipe 9 moves back and forth in the threaded hole 13 to move closer to or away from the first pipe 7.

[0040] The closed structure includes a third pipe 14, which is rotatably arranged in the second pipe 9. The third pipe 14 is provided with a switching hole 15 that matches the air outlet 6 on the second pipe 9. When the switching hole 15 is staggered with the air outlet 6, the air outlet 6 is in a blocked state.

[0041] The barrel cover 3 has a rotating shaft 16 extending from both ends, and the rotating shaft 16 is rotatably arranged on a mounting frame outside the barrel body 1. The automatic flip cover structure includes: Gear 17, said gear 17 being coaxially fixedly disposed on the rotating shaft 16; a rack 18 meshing with the gear 17; The flip cover oil cylinder 19 is fixedly arranged on the mounting frame, and the output end of the flip cover oil cylinder 19 is connected to the rack 18 for sliding with the rack 18.

[0042] The embodiments of the present application are described above in conjunction with the accompanying drawings. Unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. High-precision steel casting production process, characterized by , including the following steps: S1, Molding and Core Making: Preparation of sand molds and cores to form castings; S2, box assembly: assemble the prepared sand mold and sand core, prepare for pouring, and place the inner chiller and core support; S3, steelmaking: steel and alloy materials are melted, refined, and chemically modified by removing harmful elements, removing inclusions, deoxidizing, and degassing to obtain molten steel; S4, pouring: The refined molten steel is transported from the steelmaking furnace to the pouring position using a pouring ladle, and then the molten steel in the pouring ladle is poured into the casting mold. Nitrogen protection is used during the transportation and pouring process to prevent the molten steel from oxidation; S5, cooling: After pouring is completed, the molten steel is gradually cooled in the mold by natural cooling; S6, unpacking and sand removal: After cooling, open the mold and take out the casting. Then, remove the residual molding sand on the surface and inner cavity of the casting, and remove the core bone and the cold iron on the surface of the casting. S7, annealing heat treatment of steel castings: heat the steel castings to 20-30℃ above AC3, keep warm and then cool.

2. The high-precision steel casting production process according to claim 1, characterized in that: The box closing work is carried out according to the following steps: S2.1: Check, clean and repair all sand molds and sand cores, and check the drying degree of the sand cores and whether the ventilation channels are unobstructed; S2.2: Load the sand core into the sand mold to ensure the wall thickness of the casting, fix the sand core, exhaust the core head and fill the gaps at the joints; S2.3: Remove loose sand from the mold and place a circle of mud strips or asbestos rope on the parting surface along the periphery of the cavity to ensure that the parting surface is tightly fitted after the mold is closed to prevent liquid metal from flowing out of the gap between the parting surfaces. S2.4: Place the weight or secure the mold with bolts or metal clips, and place the pouring cup and riser ring.

3. The high-precision steel casting production process according to claim 1, characterized in that: The pouring ladle comprises: A barrel body (1), wherein the barrel body (1) is open at the top, the barrel body (1) is used to contain molten steel, and a barrel spout (2) for the molten steel to flow out is provided on the barrel body (1); A barrel cover (3), the barrel cover (3) is used to cover the opening above the barrel body (1), and the barrel cover (3) is provided with an automatic flip-up structure; A nitrogen introduction mechanism is used to introduce nitrogen into the barrel cover (3).

4. The high-precision steel casting production process according to claim 3, characterized in that: The nitrogen introduction mechanism comprises: An air intake pipe (4), wherein an air inlet (5) of the air intake pipe (4) is exposed outside the barrel cover (3), and an air outlet (6) of the air intake pipe (4) is located inside the barrel cover (3); An air supply source is connected to the air inlet (5) of the air inlet pipe (4), and compressed nitrogen is stored in the air supply source.

5. The high-precision steel casting production process according to claim 4, characterized in that: The air intake pipe (4) comprises: a first pipe (7), wherein one end of the first pipe (7) is exposed outside the barrel cover (3) as an air inlet (5), and the other end of the first pipe (7) has a diameter that gradually decreases and forms a cone; a second pipe (9), wherein the inner diameter of the second pipe (9) is the same as the outer diameter of the first pipe (7), the second pipe (9) and the first pipe (7) are on the same axis, the second pipe (9) is provided with the above-mentioned air outlet (6), and the end of the second pipe (9) away from the first pipe (7) is provided with an exhaust port (10), when the second pipe (9) is sleeved on the tapered end (8) of the first pipe (7), it is in the intake state of the air intake pipe (4), and when the second pipe (9) is away from the tapered end (8) of the first pipe (7) and forms an exhaust gap with the tapered end (8), it is in the exhaust state of the air intake pipe (4); A switching structure is provided, wherein the switching structure is used to switch the air intake pipe (4) between an air intake state and an air exhaust state. When the air intake pipe (4) is in the air exhaust state, the air outlet (6) on the second pipe (9) is blocked by the closing structure.

6. The high-precision steel casting production process according to claim 5, characterized in that: The first pipe (7) is also provided with an air outlet (6).

7. The high-precision steel casting production process according to claim 6, characterized in that: A detachable closing cover (11) is provided at the exhaust port (10).

8. The high-precision steel casting production process according to claim 7, characterized in that: The switching mechanism comprises an external thread (12) provided on the outside of the second pipe (9) and a threaded hole (13) opened on the barrel cover (3); the second pipe (9) is screw-connected to the barrel cover (3).

9. The high-precision steel casting production process according to claim 8, characterized in that: The closed structure comprises a third pipe (14), the third pipe (14) being rotatably arranged in the second pipe (9), and a switching hole (15) matching the air outlet (6) on the second pipe (9) being opened on the third pipe (14), and the air outlet (6) being in a blocked state when the switching hole (15) and the air outlet (6) are misaligned.

10. The high-precision steel casting production process according to claim 9, characterized in that: Rotating shafts (16) extend from both ends of the barrel cover (3), and the rotating shafts (16) are rotatably mounted on a mounting frame outside the barrel body (1). The automatic cover flipping structure includes: A gear (17), wherein the gear (17) is coaxially fixedly disposed on the rotating shaft (16); a rack (18), wherein the rack (18) is meshed with the gear (17); The flip cover oil cylinder (19) is fixedly arranged on the mounting frame, and the output end of the flip cover oil cylinder (19) is connected to the rack (18) for sliding with the rack (18).

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