A special sand box for V-process casting

Abstract

This invention proposes a sand box specifically for V-process casting, relating to the field of casting molding technology. It includes a controller and detachably fixed upper and lower sand boxes. The tops of the upper and lower sand boxes are respectively detachably fixed with top and bottom connecting covers. Each top and bottom connecting cover has six insert plates, with each plate corresponding to the previous one. The insert plates have arc-shaped openings on the side facing the mold cavity, with a gap between the arc-shaped openings and the cavity. This invention uses six sets of detachable insert plates, and the arc-shaped openings create a gap with the cavity, avoiding direct compression of the sand mold and precisely separating independent spaces such as area A, area B, area C, area D, and riser area. This allows for differentiated evacuation control based on the solidification characteristics of different parts of the stepped shaft casting, significantly improving casting quality stability, yield, and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of casting molding technology, specifically a sand box for V-process casting. Background Technology

[0002] V-process casting is a special casting process that uses vacuum negative pressure to compact dry sand into shape. Traditional V-process sand boxes often use a simple method of wrapping a snake-skin tube around the outer wall of the sand box to create a vacuum. This method has problems such as uneven vacuum distribution, poor sealing reliability, low air extraction efficiency, and easy wear and damage to the snake-skin tube.

[0003] Chinese utility model patent, authorization announcement number CN201906797U, discloses a sand box specifically for V-process casting, comprising an outer wall and an inner wall of the sand box, with a negative pressure chamber formed between the two walls. The inner wall of the sand box is provided with air extraction holes and a filter screen for filtering sand installed at the air extraction holes. An air extraction pipe is also provided in the middle of the sand box, and the surface of the air extraction pipe is perforated. An air extraction pipe is connected to the outer wall of the sand box. Combining air extraction through the extraction pipe and air extraction from all sides can stabilize the negative pressure within the sand box. Actual production use has shown significant results, solving the problem of uneven negative pressure in sand boxes currently used for large and medium-sized castings in the domestic V-process casting, and enabling the production of large and complex castings.

[0004] For example, Chinese utility model patent CN208853668U discloses a V-process casting sand box, comprising a sand box body, an inner wall and an outer wall, with a first ventilation system between the inner and outer walls. The first ventilation system draws air from a first exhaust port on the sand box body. A second ventilation system is located at intervals on the inner side of the sand box's inner wall, consisting of mesh-like ventilation pipes. A second exhaust port is located on the sand box body, through which the second ventilation system draws air. Ventilation holes are spaced along the surface of the ventilation pipes, and the pipes are covered with at least one layer of insulating mesh. This utility model solves the limitation of not being able to meet the hardness requirements of the sand mold after product molding, thus improving product quality. Furthermore, because the ventilation system can draw air separately, it reduces the workload and saves energy.

[0005] For stepped shaft castings with a stepped structure and significant cross-sectional changes, the casting process faces special challenges: the thicker middle section has a large heat capacity and solidifies slowly, making it prone to shrinkage defects; the thinner sections on both sides and the chamfered transition zone where the thickness and thinness meet solidify quickly, making them prone to thermal cracking due to obstructed shrinkage; traditional single-vacuum sand boxes cannot implement differentiated process control for different parts of the casting, making it difficult to simultaneously meet the needs of feeding and crack prevention, resulting in low casting yield and unstable quality. Summary of the Invention

[0006] The purpose of this invention is to provide a sand box specifically for V-process casting, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a special sand box for V-process casting, comprising a controller and an upper sand box and a lower sand box that are detachably fixed together. The top of the upper sand box and the lower sand box are respectively detachably fixed with a top connecting cover and a bottom connecting cover. Each of the top connecting cover and the bottom connecting cover has six insert plates, with the upper and lower insert plates corresponding one to one. The side of the insert plate facing the mold cavity forms an arc-shaped opening, and there is a gap between the arc-shaped opening and the mold cavity. Both sides of the top insert plate are in contact with the inner wall of the upper sand box, and both sides of the bottom insert plate are in contact with the inner wall of the lower sand box. A U-shaped plate is provided on the side of the insert plate facing the riser, and a riser zone is formed between the U-shaped plate and the riser; The upper and lower six sets of insert plates divide the inner cavity of the sand box into two A zones, two B zones, two C zones, and one D zone. The two A zones, two B zones, and two C zones are located on both sides of the D zone. Pressure sensors that are electrically connected to the controller are fixed to the side of the plug-in plates in areas B, C, and D. The sand box is equipped with an air extraction device, which independently extracts air from the riser area, D area, two B areas and two C areas.

[0008] Furthermore, air inlets are provided on both sides of the upper sand box or the lower sand cavity.

[0009] Furthermore, the air intake component includes buffer chambers on both sides of the sand box, with several air intake holes on the sides of the buffer chambers. A vent pipe connected to the buffer chambers is fixed on the side of the sand box, and a first solenoid valve electrically connected to the controller is connected to the body of the vent pipe. A first filter screen is fixed inside the sand box to block the air intake holes.

[0010] Furthermore, the air extraction device includes a third and a fourth air extraction pipe located in two B zones, a fifth and a sixth air extraction pipe located in two C zones, a second air extraction pipe located in a D zone, and a first air extraction pipe located in a riser zone. Several air extraction holes are provided on the bottom rod of all the air extraction pipes, and a second filter screen is fixed on the bottom rod of all the air extraction pipes to block the air extraction holes. The air extraction device also includes an air extraction component.

[0011] Furthermore, the air extraction component includes a first connecting pipe fixedly connected to the first and second air extraction pipes, a second connecting pipe fixedly connected to the fifth and sixth air extraction pipes, and a third connecting pipe fixedly connected to the third and fourth air extraction pipes. The ends of the first connecting pipe, the second connecting pipe, and the third connecting pipe are fixedly connected to a vertical pipe; The first connecting pipe, the second connecting pipe, and the third connecting pipe are respectively connected to the second solenoid valve, the third solenoid valve, and the fourth solenoid valve on the pipe body near the vertical pipe.

[0012] Furthermore, positioning components are provided on both sides of the upper and lower sand boxes.

[0013] Furthermore, the positioning component includes a top fixing plate fixed to the side of the upper sand box and a bottom fixing plate fixed to the side of the lower sand box. A movable plate is provided at the bottom of the bottom fixing plate, and a plug rod is fixed at the top of the movable plate, which is movably inserted into the top fixing plate and the bottom fixing plate. A spring is connected between the bottom fixing plate and the movable plate, and a guide rod is fixed at the top of the movable plate, which is movably inserted into the bottom fixing plate.

[0014] Furthermore, several corner plates are fixed to the front and back of both the upper and lower sand boxes, and lifting holes are provided on the plates.

[0015] Furthermore, the top of the upper sand box is provided with several positioning holes, and the bottom of the top connecting cover is fixed with several positioning rods that are compatible with the positioning holes and are equal in number.

[0016] Compared with existing technologies, this V-process casting sand box has the following advantages: This V-process casting sand box is equipped with six sets of detachable insert plates. The arc-shaped openings create a gap with the mold cavity, which not only avoids direct compression of the sand mold in the cavity, but also accurately separates independent spaces such as area A, area B, area C, area D and riser area. Differentiated evacuation control is implemented for the solidification characteristics of different parts of the stepped shaft casting, which significantly improves the stability of casting quality, yield and production efficiency. Attached Figure Description

[0017] Figure 1 This is a left front side axial view of the present invention; Figure 2 This is a detailed view of the positioning component of the present invention; Figure 3 This is a left rear axis view of the present invention; Figure 4 This is a half-sectional view of the present invention; Figure 5 This is a bottom view of the insert plate of the present invention.

[0018] In the picture: 101. Upper sand box; 102. Lower sand box; 2. Top connecting cover; 201. Positioning rod; 3. Angle plate; 301. Lifting hole; 4. Positioning components; 401. Bottom fixing plate; 402. Movable plate; 403. Top fixing plate; 404. Insert rod; 405. Spring; 406. Guide rod; 5. Insert plate; 51. U-shaped plate; 501. Area A; 502. Area B; 503. Area C; 504. Area D; 505. Riser area; 601. Buffer chamber; 602. Vent pipe; 603. First solenoid valve; 604. Air inlet; 605. First filter screen; 7. Pressure sensor; 801. First extraction pipe; 802. Second extraction pipe; 803. Third extraction pipe; 804. Fourth extraction pipe; 805. Fifth extraction pipe; 806. Sixth extraction pipe; 807. First connecting pipe; 808. Second connecting pipe; 809. Third connecting pipe; 810. Vertical pipe; 811. Second solenoid valve; 812. Third solenoid valve; 813. Fourth solenoid valve; 9. Second filter. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The sand box in this solution is specifically designed for V-process casting, especially for V-process casting of stepped shaft castings.

[0021] Please see Figures 1-5 The present invention provides the following implementation scheme: a sand box for V-process casting, including a controller, and an upper sand box 101 and a lower sand box 102 detachably fixed together by detachable connectors. A top connecting cover 2 and a bottom connecting cover are detachably fixed to the top of the upper sand box 101 and the lower sand box 102 by detachable connectors. To facilitate positioning and installation of the connecting covers, several positioning holes are provided on the top of the upper sand box 101 and the lower sand box 102. Several positioning rods 201, matching the positioning holes and equal in number, are fixed to the bottom of the top connecting cover 2 and the bottom connecting cover. The detachable connectors in this scheme can be a combination of positioning pins and bolts or a snap-fit ​​connector. For easy box assembly, such as... Figure 1 and Figure 2As shown, positioning components 4 are provided on both sides of the upper sand box 101 and the lower sand box 102. The positioning component 4 includes a bottom fixing plate 401 fixedly installed on the side of the lower sand box 102, and a top fixing plate 403 fixedly installed on the side of the upper sand box 101, corresponding vertically to the bottom fixing plate 401. A movable plate 402 is elastically connected to the bottom fixing plate 401 by a spring 405. A rod 404 and a guide rod 406 are vertically fixed on the movable plate 402. The bottom fixing plate 401 and the top fixing plate 403 are provided with holes for the rod 404 to pass through. The bottom fixing plate 401 is also provided with a guide hole for the guide rod 406 to slide.

[0022] One advantage of this positioning component 4 is that when sand is loaded to form the cavity, the lower sand box 102 is upside down on the mold plate. At this time, the top surface of the insert rod 404 is pressed against the top surface of the suction plate, and the movable plate 402 is moved by the elastic deformation of the spring 405, so as not to affect the placement stability of the lower sand box 102.

[0023] Additionally, during the assembly process, the lower sand box 102 is flipped over, and the spring 405 returns to its original position, causing the insertion rod 404 to extend to one side of the upper sand box 101. A crane then lifts the upper sand box 101 directly above the lower sand box 102. Align the hole on the top fixing plate 403 on the side of the upper sand box 101 with the insertion rod 404, and then slowly lower the upper sand box 101. Guided by the guide rod 406, the insertion rod 404 is inserted into the hole of the top fixing plate 403, realizing the initial positioning of the upper sand box 101 and the lower sand box 102. This effectively avoids damage to the mold cavity or affects the casting accuracy due to misalignment of the sand boxes during mold closing. The guide rod 406 can prevent the insertion rod 404 from shifting or bending during the insertion process, ensuring the accuracy and stability of the positioning.

[0024] To facilitate the hoisting and transportation of the sand boxes, several corner plates 3 are welded and fixed to the front and back of the upper sand box 101 and the lower sand box 102. Each corner plate 3 has a circular lifting hole 301 in the center of its body.

[0025] like Figure 4 and Figure 5As shown, six insert plates 5 are fixed on both the top connecting cover 2 and the bottom connecting cover. The two sides of the top insert plate 5 are in contact with the inner wall of the upper sand box 101, and the two sides of the bottom insert plate 5 are in contact with the inner wall of the lower sand box 102. The corresponding upper and lower insert plates 5 are inserted into the molding sand, dividing the inner cavity of the sand box into multiple independent areas. An arc-shaped opening is formed on the side of the insert plate 5 facing the casting cavity, and a gap is maintained between this arc-shaped opening and the cavity. This isolates the airflow in each area while avoiding excessive compression of the sand mold. A U-shaped plate 51 is fixedly installed on the side of the insert plate 5 located on the riser side. The U-shaped plate 51 and... The risers enclose each other to form an independent riser zone 505. Through the arrangement of six sets of upper and lower insert plates 5, the inner cavity of the sand box is finally divided into two A zones 501, two B zones 502, two C zones 503, and a central D zone 504. The two A zones 501, two B zones 502, and two C zones 503 are symmetrically arranged on both sides of the D zone 504. This partitioning design precisely corresponds to the structure of the stepped shaft: the D zone 504 corresponds to the middle thick rod section, the B zones 502 and C zones 503 correspond to the thin rod sections on both sides and the chamfered transition area, the A zone 501 corresponds to the outer area of ​​the shaft end, and the riser zone 505 is separated for feeding.

[0026] Inside the lower sand box 102, on the side of the insert plate 5 corresponding to one of the B area 502, C area 503 and D area 504, pressure sensors 7 electrically connected to the controller are fixedly installed. These sensors are used to monitor the actual vacuum pressure in the cavity of the corresponding area in real time and provide data feedback for closed-loop control.

[0027] like Figure 3 and Figure 4As shown, an air extraction device is installed inside the upper sand box 101. This device independently extracts air from the riser zone 505, zone D 504, the two zones B 502, and the two zones C 503. The air extraction device includes a third extraction pipe 803 and a fourth extraction pipe 804 located in the two zones B 502, a fifth extraction pipe 805 and a sixth extraction pipe 806 located in the two zones C 503, a second extraction pipe 802 located in zone D 504, and a first extraction pipe 801 located in the riser zone 505. All extraction pipes have pointed tips at the bottom of their stems, and each stem has several extraction holes covered with a second filter screen 9 to prevent molding sand from entering. The air extraction device also includes extraction components, which include a first connecting pipe 807, a second connecting pipe 808, and a third connecting pipe 809. Specifically, the first connecting pipe 807 connects to... The first suction pipe 801 and the second suction pipe 802 are connected, the second connecting pipe 808 is connected to the fifth suction pipe 805 and the sixth suction pipe 806, and the third connecting pipe 809 is connected to the third suction pipe 803 and the fourth suction pipe 804. The ends of the first connecting pipe 807, the second connecting pipe 808 and the third connecting pipe 809 are connected to a vertical pipe 810. The vertical pipe 810 is connected to a vacuum pump. On this connection path (on the pipe body of the first connecting pipe 807, the second connecting pipe 808 and the third connecting pipe 809 on the side of the vertical pipe 810), the second solenoid valve 811, the third solenoid valve 812 and the fourth solenoid valve 813 are respectively installed. By independently controlling the opening and closing and the opening degree of these solenoid valves by the controller, the independent or linkage suction control of the riser area 505, the D area 504 and the two sides B area 502 and C area 503 can be realized.

[0028] like Figure 1 and Figure 4As shown, air inlets are provided on both sides of the upper sand box 101 and the lower sand box 102. Each air inlet includes a buffer cavity 601 formed within the side wall of the sand box. Several air inlets 604 leading into the interior of the sand box are formed on the side of the buffer cavity 601. A vent pipe 602 connected to the buffer cavity 601 is fixed to the outside of the sand box. A first solenoid valve 603 electrically connected to the controller is connected to the body of the vent pipe 602. A first filter screen 605 blocking the air inlets 604 is fixed to the inside of the sand box. A storage tank containing dry gas is connected to the outside of the vent pipe 602. The controller controls the opening and closing of the first solenoid valve 603 and adjusts its opening degree, introducing a small amount of dry gas into areas A 501 on both sides. The core function of the drying gas is to dynamically balance pressure: when a certain area needs to be quickly depressurized, gas can be introduced to neutralize the negative pressure; more importantly, when the pressure in a certain area (such as D area 504) is continuously decreasing due to continuous strong pumping to maintain a high vacuum, the controller controls the first solenoid valve 603 to open and inject metered gas into the buffer chamber 601. The gas permeates into the sand mold evenly and slowly through the first filter screen 605, thereby offsetting the excessive pressure drop and dynamically stabilizing the vacuum degree of the zone at the set value. This active pressure balancing mechanism overcomes the vacuum crosstalk caused by the pores of the molding sand and enables multiple adjacent zones to maintain different vacuum degrees.

[0029] In addition, this application discloses an operating method for a sand box specifically for V-process casting: Step 1: Shaping and installing the connecting cover of the upper sand box 101 and the lower sand box 102.

[0030] The lower sand box 102 is hoisted to the molding station through the lifting holes 301 on its four corner plates 3 and placed on the model plate that has been covered with film. Then, dry quartz sand without binder is filled into the lower sand box 102 and vibrated and compacted using a vibrating table to give the molding sand a preliminary density and strength. After vibration, the excess molding sand on the top surface of the lower sand box 102 is scraped off to ensure that the surface of the sand mold is flat. The bottom connecting cover is accurately placed at the bottom of the lower sand box 102 (i.e., the top surface during molding). The lower sand box 102 and the bottom connecting cover are fixed by detachable connectors. When the bottom connecting cover is installed in place, these insert plates 5 are vertically inserted from top to bottom into the compacted sand mold, thereby pre-forming the physical boundary of the lower half of the sand mold.

[0031] The same method is used to shape the upper sand box 101 and to fix its connection to the top connecting cover 2.

[0032] Step 2: Combine the boxes.

[0033] The lower sand box 102 is flipped over so that its top surface faces upward. The upper sand box 101, which has been shaped and has its top connecting cover 2 fixed, is hoisted onto the lower sand box 102 using hoisting equipment. Guided by the positioning piece 4, it is positioned directly above the lower sand box 102. Finally, the upper sand box 101 and the lower sand box 102 are fixed together using detachable connectors.

[0034] At this time, the corresponding upper and lower insert plates 5 and U-shaped plates 51 together form a complete physical separation inside the sand mold, establishing riser zone 505, D zone 504, two B zones 502, two C zones 503 and two A zones 501.

[0035] Step 3: System connection and initialization.

[0036] Connect the vertical pipe 810 to the vacuum pump and the vent pipe 602 to the gas storage tank. The controller is initialized, and each pressure sensor 7, first solenoid valve 603, second solenoid valve 811, third solenoid valve 812 and fourth solenoid valve 813 enter the standby state.

[0037] Step 4: Dynamic vacuum control and stepped shaft casting.

[0038] 1. Before the molten metal pouring begins, the controller first starts the vacuum control program, instructing the second solenoid valve 811, the third solenoid valve 812 and the fourth solenoid valve 813 to open simultaneously, while closing the two first solenoid valves 603. The vacuum pump then uses the first connecting pipe 807, the second connecting pipe 808 and the third connecting pipe 809 to simultaneously evacuate the riser area 505, the D area 504, and all the B areas 502 and C areas 503. The goal is to establish and maintain an initial vacuum level (e.g. -0.068 to -0.08 MPa) in all key process zones before pouring. This is intended to: (1) solidify the sand mold: so that the sand mold in the entire cavity can obtain maximum strength and stability to withstand the impact and static pressure of the subsequent molten metal and prevent the mold from expanding; (2) prepare the filling power: form a uniform negative pressure environment in the cavity to provide a continuous and stable flow driving force for the molten metal after it enters.

[0039] 2. While maintaining a high vacuum in each of the above zones, pouring begins. The uniform and powerful negative pressure field effectively guides the molten metal to fill the cavity quickly and smoothly, ensuring that the thin rod section (corresponding to zone B 502 and zone C 503) can also be filled smoothly, avoiding cold shuts or incomplete pouring defects.

[0040] 3. After filling, the system automatically enters a differentiated dynamic control stage based on the preset stepped shaft solidification model and the real-time feedback from pressure sensor 7. The thin rod sections on both sides (B area 502 and C area 503) begin to solidify first. When the pressure sensor 7 detects that the pressure drop curve tends to flatten (indicating that the metal in this area has lost its fluidity), the controller immediately reduces the opening of the third solenoid valve 812 and the fourth solenoid valve 813 to reduce the evacuation intensity of B area 502 and C area 503. At the same time, the first solenoid valve 603 in the corresponding area can be slightly opened to inject a small amount of dry gas into the buffer chamber 601. The two work together to rapidly and steadily reduce the vacuum degree of B area 502 and C area 503 to a low level (e.g., -0.03 MPa) under controlled conditions. The process principle of this operation is to actively "soften" the sand mold surrounding the thin rods and the chamfered transition area, aiming to release the tensile stress generated during solidification shrinkage in this area in advance. This is a decisive intervention measure to prevent the generation of hot cracks.

[0041] While the thin-walled area is depressurized, the thick, large middle rod section (D-section 504) and the riser (riser section 505) remain in a liquid state due to their large heat capacity and require strong compression. The controller maintains the second solenoid valve 811 in a high-opening state to ensure that the highest vacuum degree (e.g., -0.072 MPa) is continuously applied to D-section 504. Since the volume of riser section 505 is smaller than that of D-section 504, the vacuum degree of riser section 505 is greater than that of D-section 504. The sensor continuously monitors the pressure. If the pressure is lower than the set target due to continuous strong pumping, the controller adjusts the first solenoid valve 603 to inject a very small amount of gas to offset the over-pumping, thereby stabilizing the vacuum degree of D-section 504 at the set value. This "pumping-compensation" closed loop ensures the stability of the compression pressure.

[0042] 4. When the pressure sensor 7 in zone D 504 shows that the pressure has remained stable for a long time, and the coarse rod part has been confirmed to be completely solidified according to the thermal calculation model, the casting enters the final solidification stage. The controller closes the second solenoid valve 811, the third solenoid valve 812 and the fourth solenoid valve 813, and stops the evacuation of the riser zone 505, zone D 504, and all zones B 502 and C 503. Then, the first solenoid valves 603 on both sides are opened to introduce gas into zones A 501 on both sides, so that the internal pressure of the entire system gradually returns to atmospheric pressure. The sand mold naturally collapses due to the loss of vacuum support, making it easy to remove and clean the casting.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A sand box for V-process casting, comprising a controller and an upper sand box (101) and a lower sand box (102) that are detachably fixed together, characterized in that: The top of the upper sand box (101) and the lower sand box (102) are respectively detachably fixed with a top connecting cover (2) and a bottom connecting cover. The top connecting cover (2) and the bottom connecting cover are each fixed with six insert plates (5). The upper and lower insert plates (5) correspond one to one. The insert plate (5) has an arc-shaped opening on the side facing the cavity. There is a gap between the arc-shaped opening and the cavity. Both sides of the top insert plate (5) are in contact with the inner wall of the upper sand box (101), and both sides of the bottom insert plate (5) are in contact with the inner wall of the lower sand box (102). A U-shaped plate (51) is provided on the side of the insert plate (5) facing the riser, and a riser area (505) is formed between the U-shaped plate (51) and the riser. The upper and lower six sets of insert plates (5) divide the inner cavity of the sand box into two A areas (501), two B areas (502), two C areas (503) and one D area (504). The two A areas (501), two B areas (502) and two C areas (503) are set on both sides of the D area (504); Inside the sand box (102), pressure sensors (7) that are electrically connected to the controller are fixed on the side of the insert plate (5) of one of the B area (502), C area (503) and D area (504). An air extraction device is installed inside the sand box (101) to independently extract air from the riser area (505), D area (504), two B areas (502) and two C areas (503).

2. The sand box for V-process casting according to claim 1, characterized in that: Air inlets are provided on both sides of the upper sand box (101) or the lower sand box (102).

3. A sand box for V-process casting according to claim 2, characterized in that: The air intake component includes buffer chambers (601) on both sides of the sand box, a plurality of air intake holes (604) on the side of the buffer chambers (601), a vent pipe (602) connected to the buffer chambers (601) fixed on the side of the sand box, a first solenoid valve (603) electrically connected to the controller connected to the pipe body of the vent pipe (602), and a first filter screen (605) fixed inside the sand box to block the air intake holes (604).

4. A sand box for V-process casting according to claim 1, characterized in that: The air extraction device includes a third air extraction pipe (803) and a fourth air extraction pipe (804) located in two B zones (502), a fifth air extraction pipe (805) and a sixth air extraction pipe (806) located in two C zones (503), a second air extraction pipe (802) located in a D zone (504), and a first air extraction pipe (801) located in a riser zone (505). Several air extraction holes are provided on the bottom rod of all the air extraction pipes, and a second filter screen (9) is fixed on the bottom rod of all the air extraction pipes to block the air extraction holes. The air extraction device also includes an air extraction component.

5. A sand box for V-process casting according to claim 4, characterized in that: The air extraction component includes a first connecting pipe (807) fixedly connected to the first air extraction pipe (801) and the second air extraction pipe (802), a second connecting pipe (808) fixedly connected to the fifth air extraction pipe (805) and the sixth air extraction pipe (806), and a third connecting pipe (809) fixedly connected to the third air extraction pipe (803) and the fourth air extraction pipe (804). The ends of the first connecting pipe (807), the second connecting pipe (808) and the third connecting pipe (809) are fixedly connected to the vertical pipe (810). The first connecting pipe (807), the second connecting pipe (808), and the third connecting pipe (809) are respectively connected to the second solenoid valve (811), the third solenoid valve (812), and the fourth solenoid valve (813) on the side of the pipe body near the vertical pipe (810).

6. A sand box for V-process casting according to claim 1, characterized in that: Positioning elements (4) are provided on both sides of the upper sand box (101) and the lower sand box (102).

7. A sand box for V-process casting according to claim 6, characterized in that: The positioning component (4) includes a top fixing plate (403) fixed to the side of the upper sand box (101) and a bottom fixing plate (401) fixed to the side of the lower sand box (102). A movable plate (402) is provided at the bottom of the bottom fixing plate (401). A plug rod (404) is fixed at the top of the movable plate (402) and is movably inserted into the top fixing plate (403) and the bottom fixing plate (401). A spring (405) is connected between the bottom fixing plate (401) and the movable plate (402). A guide rod (406) is fixed at the top of the movable plate (402) and is movably inserted into the bottom fixing plate (401).

8. A sand box for V-process casting according to claim 1, characterized in that: The upper sand box (101) and the lower sand box (102) are each fixed with several corner plates (3) on the front and back, and the corner plates (3) are provided with lifting holes (301).

9. A sand box for V-process casting according to claim 1, characterized in that: The top of the upper sand box (101) and the lower sand box (102) are provided with several positioning holes, and the bottom ends of the top connecting cover (2) and the bottom connecting cover are fixed with several positioning rods (201) that are compatible with the positioning holes and are equal in number.

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