Casting sand box with waste gas collecting and treating functions

Abstract

The casting sand box with the waste gas collecting and treating function comprises a sand box body and a cavity, a mounting opening is formed in the sand box body, and a waste gas treating cavity is formed in the mounting opening; a molding sand screen, a tubular connecting piece, a three-way catalyst and an exhaust pipe are sequentially arranged in the waste gas treatment cavity, a heat transfer auxiliary piece penetrating through the molding sand screen arranged in a floating mode is further arranged in the side direction of the tubular connecting piece, a secondary heat transfer auxiliary piece extends out of the heat transfer auxiliary piece, and the heat transfer auxiliary piece and the secondary heat transfer auxiliary piece are embedded into molding sand when used. The casting heat is transferred into the waste gas treatment cavity through heat transfer of the heat transfer auxiliary part, and the optimal working temperature of the three-way catalyst is achieved by means of the heat preservation material packaged in the waste gas treatment cavity. The casting waste gas is efficiently collected and purified through heat generated by the casting process, and powerful technical support is provided for environmental protection and sustainable development of the casting industry.

Description

Technical Field

[0001] The present invention relates to the technical field of metal casting processing machinery, mainly to the sand boxes used at the casting site, and particularly to a casting sand box with an exhaust gas collection and treatment function. Background Art

[0002] There is no national standard yet for the treatment of soot and exhaust gas in the pouring process in the casting field. After pouring molten metal into the sand box during the production process in the casting workshop, the sand box is filled with molding sand, and a solid resin film is covered on the surface of the molding sand grains before molding. After the molten metal is added to the sand box, it will generate continuous high heat and impact on the surface of the molding sand. The organic binder in the molding sand will decompose and release various exhaust gases when heated, including water vapor, carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, and volatile organic compounds (VOCs), etc. The exhaust gas generated during the casting process not only pollutes the environment but also may pose a threat to the health of workers. Therefore, it is necessary to deal with the above problems.

[0003] The invention patent with the publication number of CN110586907A discloses a method for recovering argon gas at the casting site and a multifunctional casting weight that can collect dust and recover. By opening a through smoke channel in the weight body, the side of the smoke channel is connected to the side suction channel, the bottom surface is connected to the top suction channel, and the top surface is connected to the gas treatment chamber, and a gas treatment medium is filled in the gas treatment chamber. The pouring gas is collected and captured from the source and can be reused. However, when dealing with large sand box castings, a sufficient number of weights need to be added in this scheme. In addition, the inner cavity of the smoke channel forms a combustion chamber to ignite the insufficiently burned exhaust gas, and fuel needs to be continuously added. The high temperature of the sand box may also cause the fuel to spontaneously combust. The above problems hinder its popularization and implementation. Summary of the Invention

[0004] In view of the above situation in the background art, the purpose of the present invention is to design a casting sand box with an exhaust gas collection and treatment function, which makes full use of the sand box as the source of pouring exhaust gas and can effectively deal with the problem of exhaust gas escape in the casting workshop in combination with the environmental conditions of the casting workshop.

[0005] To achieve the above purpose, the technical solution provided by the present invention is as follows: A casting sand box with an exhaust gas collection and treatment function, including a sand box body and a cavity opened in the sand box body for containing molding sand. An exhaust gas treatment chamber is also opened on the outer periphery of the cavity. The exhaust gas treatment chamber is provided with an air inlet, and a three-way catalytic converter is arranged in the exhaust gas treatment chamber. The air inlet end of the three-way catalytic converter is communicated with the air inlet of the exhaust gas treatment chamber, and the exhaust end of the three-way catalytic converter is communicated with an exhaust pipe. The exhaust pipe passes through the exhaust gas treatment chamber and is communicated to a negative pressure device.

[0006] Further, a heat transfer auxiliary is provided in the exhaust gas treatment chamber. The heat transfer auxiliary is made of a heat-conducting material, buried in the molding sand in the mold cavity and passes through the outer wall of the exhaust gas treatment chamber to connect to the inside of the exhaust gas treatment chamber.

[0007] Further, a secondary heat transfer auxiliary is also provided on the heat transfer auxiliary.

[0008] Further, heat-insulating materials are encapsulated in the exhaust gas treatment chamber, and the heat-insulating materials can be rock wool, refractory bricks, etc.

[0009] Further, a side air inlet is provided in the exhaust gas treatment chamber along the radial direction of the three-way catalytic converter through a one-way valve. The side air inlet is a counterbore structure and extends outward to form a flared air collecting cover.

[0010] To make the replacement and maintenance of the three-way catalytic converter more convenient, the technical solution provided by the present invention further includes: a tubular connector is provided in the exhaust gas treatment chamber, and the intake end of the three-way catalytic converter is detachably connected to the tubular connector in the exhaust gas treatment chamber through a flange.

[0011] Further, the tubular connector is connected to the air inlet through a flange, the three-way catalytic converter is connected to the exhaust pipe through a flange, the heat transfer auxiliary is fixedly arranged on one side of the tubular connector, the tubular connector passes through the heat transfer member moving port of the exhaust gas treatment chamber, and the side where the heat transfer member moving port is located is a sandwich wall structure. A molding sand screen is floatingly arranged inside the sandwich wall structure along the inside of the sandwich wall, and the molding sand screen is fixed to the heat transfer auxiliary.

[0012] Further, a cover body is detachably arranged on the sand box body. The size of the cover body is not less than that of the sand box body, and at least it can cooperate with the sand box body to form a closed space for molding sand, preferably completely covering the sand box body.

[0013] Further, a maintenance door is provided on the outside of the exhaust gas treatment chamber through a chute, and a heat-insulating layer is provided in the maintenance door.

[0014] Further, a steering auxiliary is provided between the maintenance door and the chute. The steering auxiliary includes two ball heads respectively connected to the inside of the chute and the maintenance door. The two ball heads are fixedly connected through an L-shaped member. A limiting block is provided at one end of the chute. After the ball head in the chute is limited by the limiting block, the ball head in the chute rotates to make the maintenance door fit with the exhaust gas treatment chamber.

[0015] Further, an installation opening is provided on the sand box body, and the exhaust gas treatment chamber is detachably fixed in the installation opening through structures such as buckles, bolts, and sliders.

[0016] The advantages and beneficial effects of the present invention are as follows: By directly arranging an exhaust gas treatment chamber both inside and outside the sand box body and directly treating it through a three-way catalytic converter, the effect of efficiently collecting and treating foundry exhaust gas at the source of generation is achieved, avoiding the unorganized dispersion of exhaust gas in the workshop.

[0017] The molding sand screen not only plays a role in supporting the molding sand and forming the mold cavity, but also serves as a channel for exhaust gas to enter the treatment chamber, ensuring that the exhaust gas can smoothly enter the exhaust gas treatment chamber from the mold cavity, realizing the integration of structure and the diversification of functions.

[0018] By connecting a negative pressure device, the exhaust pipe can effectively discharge the exhaust gas treated by the three-way catalytic converter in a timely manner, maintaining a negative pressure state in the exhaust gas treatment chamber and ensuring the continuity and stability of exhaust gas treatment.

[0019] The exhaust gas treatment chamber is also provided with heat transfer auxiliary parts and encapsulated with heat insulation materials. The heat transfer auxiliary parts are made of heat-conducting materials and are buried in the molding sand in the mold cavity. They are rotatably connected to the inside through the outer wall of the exhaust gas treatment chamber by flanges and tubular connectors. This significantly improves the heat conduction efficiency, enabling the heat generated in the molding sand to be quickly and evenly transferred to the exhaust gas treatment chamber, providing a stable heat source for the three-way catalytic converter. It also makes full use of the large amount of difficult-to-utilize heat energy contained in the molding sand during the casting process and helps to maintain the optimal working temperature of 700 °C for the three-way catalytic converter.

[0020] The installation openings provided on the sand box body and the detachable design of the exhaust gas treatment chamber enable the exhaust gas treatment chamber to be easily integrated into the sand box body. The modular design also means enhanced independence between different components, and the failure or upgrade of a single module will not have too much impact on the entire system, providing convenience for maintenance. Brief Description of the Drawings

[0021] Figure 1 is one of the structural schematic diagrams of the present invention; Figure 2 is the internal structural schematic diagram of the exhaust gas treatment chamber of the present invention; Figure 3 is the structural schematic diagram of the inspection door of the present invention; Figure 4 is the exploded view of the partial side structure of the inspection door of the present invention; Figure 5 is the second structural schematic diagram of the present invention; Figure 6 is the structural schematic diagram of the sandwich wall structure of the present invention; Figure 7 is the structural schematic diagram of the cover body of the present invention; In the figures: 1 - Sand box body, 2 - Cavity, 3 - Exhaust gas treatment chamber, 4 - Three-way catalytic converter, 5 - Inlet, 6 - Molding sand screen, 7 - Inlet end, 8 - Exhaust pipe, 9 - Heat transfer auxiliary part, 10 - Secondary heat transfer auxiliary part, 11 - Heat insulation layer, 12 - Check valve, 13 - Side inlet, 14 - Counterbore structure, 15 - Gas collecting hood, 16 - Pipe-shaped connecting piece, 17 - Flange, 18 - Heat transfer part moving port, 19 - Sandwich wall structure, 20 - Slide groove, 21 - Inspection door, 22 - Buckle, 23 - Steering auxiliary part, 24 - Ball head, 25 - L-shaped part, 26 - Limit block, 27 - Installation port, 28 - Cover body. Detailed implementation mode

[0022] The three-way catalytic converter, also known as the "catalytic converter", is the main component for purifying the pollutants emitted by the automobile engine. Its structure from the outside to the inside is the housing, gasket and carrier in sequence. Among them, the outer shell mainly plays a role in protecting the core part. The gasket mainly plays roles such as fixing the carrier, buffering and heat insulation. The core of the three-way catalytic converter is the carrier, which is usually a honeycomb-shaped ceramic column. The carrier is coated with precious metal catalysts (such as platinum, rhodium, palladium, etc.). The exhaust gas passes through these small holes to achieve catalytic conversion. The three-way catalytic converter is usually installed in the automobile exhaust system. As an off-board purification device, it can convert harmful gases such as CO (carbon monoxide), HC (hydrocarbons) and NO x (nitrogen oxides) in the automobile exhaust gas into harmless carbon dioxide, water and nitrogen through oxidation and reduction. When the high-temperature exhaust gas passes through the purification device, the purifying agent in the three-way catalytic converter will enhance the activity of CO, HC and NO x among the three gases, and promote them to carry out a certain oxidation-reduction chemical reaction. Among them, CO is oxidized into colorless and non-toxic carbon dioxide gas at high temperature; HC compounds are oxidized into water (H2O) and carbon dioxide at high temperature; NO x is reduced into nitrogen and oxygen. The three harmful gases become harmless gases, purifying the automobile exhaust gas. However, the working temperature of the three-way catalytic converter is generally 400~800℃. Therefore, although this technical solution has excellent effects, its application is limited.

[0023] Generally, the pouring temperature directly affects the change of the component content in the exhaust gas. When pouring molten iron at 1350℃, the exhaust gas temperature is about 800℃, and the exhaust gas is mainly a mixed gas of pyrolysis and degradation. When casting steel, the pouring temperature reaches 1600℃, so the carbon precipitation situation is relatively serious, and HC is more in the exhaust gas components.

[0024] The present invention constructs an embedded exhaust gas treatment system through the recycling of the heat in the casting process and the self-maintaining mechanism of the working temperature of the three-way catalytic converter. By adopting the extended surface heat transfer theory, a multi-stage heat bridge structure is formed through heat transfer auxiliary components (primary / secondary), significantly increasing the heat transfer area. The heat transfer rate calculation formula in the present invention is as follows:

[0025] In the formula: Q is the heat transfer rate (w); k is the thermal conductivity of cast iron (W / (m*K)); A is the total surface area of the heat transfer auxiliary component (m 2 ), ΔT is the temperature difference between the molding sand and the exhaust gas treatment chamber (°C, K); L is the length of the heat transfer path (m).

[0026] In the technical principle of the present invention, the thermal conductivity of cast iron is taken as 50 W / (m*K), and the total surface area of the heat transfer auxiliary component, the sum of the primary and secondary structures can reach 0.5 - 1.2 m 2 , and the length of the heat transfer path is controlled within 0.3 - 0.5 m.

[0027] To improve the working efficiency of the three-way catalysis, the present invention reduces heat loss through heat insulation materials such as rock wool (thermal conductivity of 0.03 - 0.05 W / (m*K)), so that the chamber temperature is stabilized between 650 - 750 °C. According to the finite element analysis, under the condition of pouring molten iron at 1350 °C, the temperature curve of the exhaust gas treatment chamber shows that it reaches 600 °C within 30 minutes after pouring, and stabilizes at 720 ± 20 °C after 2 hours and can be maintained for 2 - 4 hours.

[0028] In the embodiment shown in the present invention, the three-way catalytic converter selects the three-way catalytic converter with the model CCIC-800HT produced by Corning, and the structure of its catalytic carrier is cordierite honeycomb ceramic. The technical parameters of this carrier include 400 mesh / square inch and a wall thickness of 0.1 mm.

[0029] In the embodiment shown in the present invention, the negative pressure system adopts a Venturi effect vacuum generator, and the working vacuum degree is from -50 kPa (cavity side) to -20 kPa (gas collecting hood side), and the flow matching degree is 0.5 - 0.8 m 3 / min of the air extraction rate per cubic meter of cavity solvent gas.

[0030] Regarding the stress analysis and verification of the heat transfer auxiliary component, at a temperature difference of 1000 °C, the maximum stress of the sand box cast iron structure is 185 MPa < the allowable stress (the allowable stress of HT250 cast iron is 250 MPa). The flange sealing performance verification uses ANSYS to simulate the flange connection, and at 700 °C, the sealing pressure of the gasket (graphite wound gasket) remains > 2 MPa.

[0031] It should be noted that among the technical features shown in the present invention, the heat insulation material (rock wool / refractory brick) is precisely deployed in the exhaust gas treatment chamber. Its core function is to maintain the operating temperature of the three-way catalytic converter, rather than blocking the heat conduction path from the molding sand to the heat transfer auxiliary. The heat insulation material reduces the heat dissipation of the chamber to the environment, while the metal heat conduction path of the heat transfer auxiliary is independent and efficient. The two complement each other rather than conflict.

[0032] The following will further describe the specific implementation manners of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0033] Embodiment Please refer to Figures 1 to 2 、 Figure 7 A foundry sand box with an exhaust gas collection and treatment function, including a sand box body 1 and a cavity 2 opened inside the sand box body 1 for containing molding sand. An exhaust gas treatment chamber 3 is further provided on the outer periphery of the cavity 2. The air inlet 5 of the exhaust gas treatment chamber 3 is connected to the inside of the cavity 2 through a molding sand screen 6. A cover body 28 is provided on the top of the sand box body 1. A three-way catalytic converter 4 is provided in the exhaust gas treatment chamber 3. The air inlet end 7 of the three-way catalytic converter 4 is connected to the air inlet 5 of the exhaust gas treatment chamber 3, and the exhaust end of the three-way catalytic converter is connected to an exhaust pipe 8. The exhaust pipe 8 passes through the exhaust gas treatment chamber 33 and is connected to a negative pressure device. Optionally, the cover body 28 is also connected to the exhaust gas treatment chamber 3. The temperature at the cover body can reach 500-700 degrees Celsius in the initial stage of pouring. Therefore, an exhaust gas treatment chamber can be added at the cover body, but its treatment efficiency is lower than that of the exhaust gas treatment chamber 3 opened in the sand box body. The sealed structure of the cover body is more beneficial to prevent exhaust gas leakage. The exhaust gas treatment chambers at the sand box body can be symmetrically arranged along the center in multiple numbers, so as to avoid uneven heating and cooling of the castings caused by the air extraction of the negative pressure devices at various places.

[0034] Please refer to Figure 2, the exhaust gas treatment chamber 3 is further provided with a heat transfer auxiliary member 9, and the heat transfer auxiliary member 9 extends a secondary heat transfer auxiliary member 10 inside the cavity. The heat transfer auxiliary member 9 is made of a heat-conducting material, and the heat transfer auxiliary member 9 is buried in the molding sand in the cavity 2 and passes through the outer wall of the exhaust gas treatment chamber 3 and is connected to the inside of the exhaust gas treatment chamber 3. Through the heat transfer auxiliary member 9, the heat of the molten metal-molding sand can be conducted more efficiently, and this heat is introduced into the exhaust gas treatment chamber 3 to heat the three-way catalytic converter 4, so that the three-way catalytic converter 4 reaches the optimal working temperature, thereby achieving better technical effects. Optionally, the exhaust gas treatment chamber 3 is encapsulated with a heat-insulating layer made of a heat-insulating material. The heat-insulating layer is made of a heat-insulating material, and the heat-insulating material can be rock wool, refractory bricks, etc. The exhaust gas treatment chamber 3 is also provided with a side air inlet 13 along the radial direction of the three-way catalytic converter 4 through a one-way valve 12. The side air inlet 13 is a counterbore structure 14 and extends outward to form a flared air collecting cover 15. The side air inlet 13 is used to absorb the exhaust gas and secondary nitrogen oxide gas generated by the high heat of casting in the air, and to realize the mixing of air and exhaust gas.

[0035] Optionally, the exhaust gas treatment chamber 3 provided in the sand box body 1 is partially embedded in the sand box body 1. Optionally, the exhaust gas treatment chamber 3 provided in the sand box body 1 is arranged close to the outer wall of the sand box body, and the exhaust gas collection and treatment work of the sand box body closed by the air collecting cover 15 is carried out.

[0036] Optionally, the cover body is also connected to a positive pressure device, so that the collection and treatment of exhaust gas are more rapid.

[0037] For the replacement and maintenance of the three-way catalytic converter 4 to be more convenient, please refer to Figure 2 、 Figure 6 , the technical solution provided by the present invention further includes: a tubular connector 16 is arranged in the exhaust gas treatment chamber 3, and the intake end 7 of the three-way catalytic converter 4 is detachably connected to the tubular connector 16 in the exhaust gas treatment chamber 3 through a flange 17. The tubular connector 16 is connected to the air inlet 5 through a flange 17. The three-way catalytic converter is connected to the exhaust pipe 8 through a flange 17. The heat transfer auxiliary member 9 is fixedly arranged on one side of the tubular connector 16. The tubular connector 16 passes through the heat transfer member moving port 18 of the exhaust gas treatment chamber 3. The side where the heat transfer member moving port 18 is located is a sandwich wall structure 19. Inside the sandwich wall structure 19, a molding sand screen 6 is floatingly arranged along the inside of the sandwich wall, and the molding sand screen 6 is fixed to the heat transfer auxiliary member 9. In the actual operation process, the tubular connector 16 connected by the flange structure can rotate a certain angle during installation, so as to adjust the position of the heat transfer auxiliary member 9 inside the molding sand and avoid interference with the position of the casting.

[0038] Please refer to Figures 3 to 5, the sand box body 1 is provided with an installation opening 27, and the waste gas treatment chamber 3 is detachably fixed to the installation opening 27 through a buckle 22. This facilitates the addition of this embodiment to an existing or already manufactured blocked sand box. An inspection door 21 is arranged on the outer side of the waste gas treatment chamber 3 through a sliding groove 20. An insulating layer 10 is arranged in the inspection door 21. The waste gas treatment chamber 3 is connected to the sand box body 1 through a buckle 22. A steering auxiliary part 23 is arranged between the inspection door 21 and the sliding groove 20. The steering auxiliary part 23 includes two ball heads 24 respectively connected to the inside of the sliding groove 20 and the inspection door 21. The two ball heads 24 are fixedly connected through an L-shaped part 25. A limiting block 26 is arranged at one end of the sliding groove 20. After the ball head 24 in the sliding groove 20 is limited by the limiting block 26, the ball head 24 in the sliding groove can rotate to make the inspection door 21 fit with the waste gas treatment chamber 3. The above settings can prevent the inspection door from sliding along the inside of the sand box body 1, resulting in an overly complex sand box structure that is inconvenient to process, and is beneficial to the modular setting of the present invention. The L-shaped part 25 and the inspection door structure of the sliding groove can completely fit into the waste gas treatment chamber 3 in terms of the thickness of the inspection door compared with the hinged door setting, and the sealing and heat preservation effects are better. Each part can adopt a modular setting and be replaced and maintained through a flange.

[0039] During the casting process, the cavity 2 inside the sand box body 1 is used to hold the molding sand. The height of the molding sand should meet the requirement of not being higher than the top surface of the waste gas treatment chamber 3. Preferably, the height of the molding sand reaches 2 / 3 of the height of the waste gas treatment chamber 3 set in the sand box body. When waste gas is generated during the casting operation, the casting sand box is closed with a cover 28, so that the waste gas must pass through the waste gas treatment chamber 3 and its connected negative pressure device before being discharged. These waste gases first pass through the molding sand screen 6, which allows the waste gas to pass through while preventing the molding sand from entering the waste gas treatment system. The waste gas then enters the waste gas treatment chamber 3. Inside the waste gas treatment chamber 3, the waste gas is guided to the intake end 7 of the three-way catalytic converter 4. The exhaust gas after being treated by the three-way catalytic converter 4 has its exhaust end connected to the exhaust pipe 8. The exhaust pipe 8 is responsible for guiding the treated waste gas out of the waste gas treatment chamber 3 and transporting it to the negative pressure device. The negative pressure device generates negative pressure to ensure that the waste gas can be smoothly evacuated from the sand box body 1, thereby maintaining the effective operation of the entire waste gas collection and treatment system. It should be noted that the optional setting of the cover 28 for closing the sand box body 1 can assist the waste gas treatment work inside the waste gas treatment chamber. The waste gas treatment can be realized by utilizing the large amount of heat of the molten iron 12 to 24 hours before casting and the large amount of evaporation of the waste gas upward. After 24 hours, the cover is closed with a flange head, so that the sand box body is in a closed environment, and only the waste gas treatment chamber 3 on the outer periphery of the installation opening of the sand box body completes the waste gas treatment work.

[0040] The heat transfer auxiliary member 9 is made of a heat-conducting material, preferably a metal alloy such as cast iron. The heat transfer auxiliary member 9 extends a secondary heat transfer auxiliary member 10 inside the cavity 2. This structure increases the heat transfer area, enabling the heat of the molten metal-sand to be more efficiently conducted into the exhaust gas treatment chamber 3. The heat transfer auxiliary member 9 is not only buried in the sand but also passes through the outer wall of the exhaust gas treatment chamber 3 and is connected to its interior, thus ensuring that heat can be smoothly transferred to the three-way catalytic converter 4 to reach its optimal operating temperature. In this way, the catalytic efficiency of the three-way catalytic converter 4 is improved, and the harmful substances in the exhaust gas can be more thoroughly converted. To maintain the temperature stability in the exhaust gas treatment chamber 3 and prevent heat dissipation, an insulating layer made of insulating materials (such as rock wool, refractory bricks, etc.) is optionally encapsulated in the exhaust gas treatment chamber 3. This design helps to keep the operating temperature of the three-way catalytic converter 4 within a stable range, thereby improving its efficiency in treating exhaust gas.

[0041] In addition, the exhaust gas treatment chamber 3 is also provided with a side air inlet 13 along the radial direction of the three-way catalytic converter 4 through a one-way valve 12. The side air inlet 13 adopts a counterbore structure 14 and extends outward to form a flared air collecting hood 15. This structure is conducive to collecting and sucking in the nitrogen oxide gas generated during the casting process due to high heat. After these gases enter the exhaust gas treatment chamber 3 through the side air inlet 13, they will also be treated by the three-way catalytic converter 4, thereby further reducing the environmental pollution caused by the casting process.

[0042] A tubular connector 16 is provided inside the exhaust gas treatment chamber 3. This connector acts as a bridge to connect various key components. The intake end 7 of the three-way catalytic converter 4 is detachably connected to the tubular connector 16 through a flange 17. Such a design facilitates installation, disassembly, and maintenance. The other end of the tubular connector 16 is also connected to the air inlet 5 through a flange 17, thus ensuring the smooth inflow of exhaust gas. The tubular connector 16 is also fixedly provided with a heat transfer auxiliary member 9. The tubular connector 16 passes through the heat transfer member moving port 18 of the exhaust gas treatment chamber 3. The design of this moving port allows the flange of the tubular connector 16 to rotate at a certain angle during installation, so as to adjust the position of the heat transfer auxiliary member 9 inside the sand, avoid interference with the position of the casting, and ensure the smooth progress of exhaust gas treatment. On one side of the exhaust gas treatment chamber 3, a sandwich wall structure 19 is provided, and a sand screen 6 is floatingly arranged inside the sandwich wall structure. The sand screen 6 is fixed to the heat transfer auxiliary member 9. Such a design not only enhances the stability of the screen but also is conducive to the uniform heat transfer of the exhaust gas. Multiple installation ports can be provided and reused.

[0043] The volume of a conventional three-way catalytic converter is approximately 30 cm * 20 cm * 20 cm, while the exhaust gas treatment chamber is slightly larger than the three-way catalytic converter, and its volume can be 50 cm * 30 cm * 30 cm, which is relatively large. It should be noted that the exhaust gas treatment chamber is preferably for large and medium-sized castings. The installation position of the exhaust gas treatment chamber is preferably at the thicker surface of the casting. To facilitate the repeated use of the sand box and avoid interference with the position of the casting, it is preferred to open installation ports at one corner or two diagonal corners of the sand box. When dealing with small sand boxes, a structure can be adopted where the exhaust gas treatment chamber is installed at the top of the cover as shown in Figure 7 . However, as mentioned above, due to the influence of lower temperature on its efficacy, when the air inlet is 10 cm away from the molding sand, the efficacy at this place is about 70% of that of the side suction type.

[0044] Specifically, the technical effects achieved by the above solutions are as follows: A gas detection device is used to detect the concentrations of various gases at the site of a sand box using phenolic resin coated sand for cast iron at 1350 °C in this embodiment. The control group is the casting site of a conventional sand box for the same casting. The pouring sites of both the embodiment and the control group comply with the "Emission Standard of Air Pollutants for the Foundry Industry" GB-31573-2015.

[0045] In this embodiment, two (-80 kPa) are arranged diagonally and one exhaust gas treatment chamber (-100 kPa) is arranged on the cover. The measurement is carried out 24 hours after pouring. The height of the molding sand is at 2 / 3 of the exhaust gas treatment chamber, and the heat transfer auxiliary is buried in the molding sand.

[0046]

[0047] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A casting sand box with an exhaust gas collection and treatment function, comprising a sand box body (1) and a cavity (2) opened inside the sand box body (1) for containing molding sand, characterized in that: An exhaust gas treatment chamber (3) is also provided on the outer periphery of the cavity (2). The exhaust gas treatment chamber (3) is provided with an air inlet (5). A three-way catalytic converter (4) is arranged in the exhaust gas treatment chamber (3). The air inlet end of the three-way catalytic converter (4) communicates with the air inlet (5) of the exhaust gas treatment chamber (3), and the exhaust end of the three-way catalytic converter (4) communicates with an exhaust pipe (8). The exhaust pipe (8) is connected to a negative pressure device.

2. The casting sand box with the function of waste gas collection and treatment according to claim 1, characterized in that: The exhaust gas treatment chamber (3) is also provided with a heat transfer auxiliary member (9). The heat transfer auxiliary member (9) is made of a heat-conducting material. The heat transfer auxiliary member (9) is buried in the molding sand in the cavity and passes through the outer wall of the exhaust gas treatment chamber (3) to be connected to the inside of the exhaust gas treatment chamber (3).

3. The casting sand box with waste gas collection and treatment function according to claim 2, characterized in that: The heat transfer auxiliary member (9) is also provided with a secondary heat transfer auxiliary member (10).

4. The foundry sand box with waste gas collection and treatment function according to any one of claims 1 to 3, characterized in that: The exhaust gas treatment chamber (3) is encapsulated with a heat-insulating material.

5. The foundry sand box with waste gas collection and treatment function according to claim 1, characterized in that: The exhaust gas treatment chamber (3) is also provided with a side air inlet (13) along the radial direction of the three-way catalytic converter (4) through a one-way valve (12). The side air inlet (13) has a counterbore structure (14) and extends outwards to form a gas collecting hood (15).

6. The casting sand box with waste gas collection and treatment function according to claim 1, characterized in that: A tubular connector (16) is arranged in the exhaust gas treatment chamber (3). The air inlet end (7) of the three-way catalytic converter (4) is detachably connected to the tubular connector (16) in the exhaust gas treatment chamber (3) through a flange (17).

7. The foundry sand box with waste gas collection and treatment function according to claim 6, characterized in that: The tubular connector (16) is connected to the air inlet (5) through a flange. The three-way catalytic converter (3) is connected to the exhaust pipe (8) through a flange (17). The heat transfer auxiliary member (9) is fixedly arranged on one side of the tubular connector (16). The tubular connector (16) passes through a heat transfer member moving port (18) of the exhaust gas treatment chamber (3). The heat transfer member moving port (18) has a sandwich wall structure (19). A molding sand screen (6) is floatingly arranged inside the sandwich wall structure (19). The molding sand screen (6) is fixed to the heat transfer auxiliary member.

8. The foundry sand box with waste gas collection and treatment function according to claim 1, characterized in that: The sand box body (1) is also detachably provided with a cover body (28). The cover body (28) covers the sand box body (1) to form a sealed chamber.

9. The foundry sand box with waste gas collection and treatment function according to claim 1, characterized in that: An inspection door (21) is slidably arranged on the outer side of the exhaust gas treatment chamber (3) through a chute (20). An insulating layer (11) is arranged in the inspection door (21). A steering auxiliary member (23) is arranged between the inspection door (21) and the chute (20). The steering auxiliary member (23) includes two ball heads (24) respectively connected to the inside of the chute (20) and the inspection door (21). The two ball heads (24) are fixedly connected through an L-shaped member (25). A limit block is arranged at one end of the chute (20).

10. The casting sand box with waste gas collection and treatment function according to claim 1, characterized in that: The sand box body (1) is provided with an installation opening (27). The exhaust gas treatment chamber (3) is detachably fixed in the installation opening (27).

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