An apparatus for CO2 blowing hardening of sodium silicate sand in a foundry

Abstract

The present invention provides a device for CO2 blowing hardening of sodium silicate sand in a foundry, comprising: a recovery bottom plate, hermetically connected to the bottom end of the sand box; a blowing cover plate, hermetically connected to the top end of the sand box; a sealing frame, hermetically sleeved on the outer top of the sand box; an air cavity and a plurality of air holes. The air cavities are respectively arranged in the recovery bottom plate and the blowing cover plate, and the plurality of air holes are respectively opened in the sealing areas between the recovery bottom plate and the sand box and between the blowing cover plate and the sand box, and the air holes are communicated with the air cavities; the air cavities are communicated with the port of the CO2 gas cylinder, the port of the recovered CO2 gas storage cylinder and the air inlet and outlet of the compressor through connecting pipes and an air path control valve group, and the air path control valve group and the compressor are both signal-connected to the PLC device; by controlling the compressor, the opening and closing of the valve group, the pressure regulator, the on-line CO2 concentration tester and the PLC device through the PLC, the addition amount of sodium silicate is saved, the CO2 gas is recovered and reused, the carbon emission and the consumption of CO2 are reduced, the strength of the sand mold is ensured, and it is convenient for knocking out the sand and regenerating the used sand.

Description

Technical Field

[0001] The present invention relates to the technical field of casting equipment, and particularly relates to a device for CO2 blowing hardening of sodium silicate sand in a foundry. Background Art

[0002] At present, in casting production, the CO2 sodium silicate sand process is a molding and core-making method widely used in steel casting in China. This method can be used for single-piece and small-batch production, and can also be applied to the production of relatively large-batch castings.

[0003] The CO2 blowing hardening process of sodium silicate sand has been used since the 1950s. The sodium silicate CO2 hardening process has been widely used because of its sulfur-free, nitrogen-free, gas-free, odorless and low-cost characteristics. With the national goal of green development to reduce carbon emissions, this process lacks the recovery of CO2 used in casting and the purification of tail gas in the sand mold. Since there is CO2 tail gas in the sand mold, the strength of the sand mold is reduced, forcing an excessive addition of sodium silicate. The large addition of sodium silicate will in turn lead to difficult shakeout and difficult regeneration and recycling of used sand, increasing the casting cost of enterprises.

[0004] In view of this, the inventor of the present application has invented a device for CO2 blowing hardening of sodium silicate sand in a foundry. Summary of the Invention

[0005] Aiming at the deficiencies of the existing applied technologies, the present invention provides a device for CO2 blowing hardening of sodium silicate sand in a foundry.

[0006] The present invention solves the above technical problems through the following technical means: A device for CO2 blowing hardening of sodium silicate sand in a foundry, comprising:

[0007] A recovery bottom plate, hermetically connected to the bottom end of the sand box;

[0008] A blowing cover plate, hermetically connected to the top end of the sand box;

[0009] A sealing frame, hermetically sleeved on the outer top of the sand box;

[0010] An air cavity and a plurality of air holes. The air cavity is respectively arranged in the recovery bottom plate and the blowing cover plate. The plurality of air holes are respectively opened in the sealing areas between the recovery bottom plate and the sand box and between the blowing cover plate and the sand box, and the air holes are communicated with the air cavity; the air cavity is communicated with the port of the CO2 gas cylinder, the port of the recovered CO2 gas storage cylinder and the intake port of the compressor through connecting pipes and an air path control valve group. The outlet of the compressor is connected to the air path control valve group, and the air path control valve group and the compressor are both connected to the PLC device in a signal connection.

[0011] Further, a CO2 online detector is communicated with the air cavity in the recovery bottom plate. The CO2 online detector is connected to the PLC device in a signal connection, and the CO2 online detector is installed on the air path control valve group.

[0012] Further, the gas path control valve group includes a solenoid valve and a pressure regulating valve.

[0013] Further, the CO2 gas cylinder port, the compressor outlet, and the recovered CO2 gas cylinder port are communicated with the gas cavity located in the blowing cover plate, the compressor inlet is communicated with the gas cavity located in the recovery bottom plate, and the compressor outlet is communicated with the recovered CO2 gas cylinder port.

[0014] Further, the sealing frame includes oppositely arranged side plates and oppositely arranged end plates. The oppositely arranged end plates are located between the oppositely arranged side plates. The oppositely arranged side plates and end plates form a sealing frame with an open upper end, and the blowing cover plate is arranged at the top opening of the sealing frame.

[0015] Further, sealing gaskets are provided in the contact areas between the sealing frame and the sand box, between the recovery bottom plate and the sand box, and between the blowing cover plate and the sealing frame.

[0016] Further, a counterweight is provided on the top of the blowing cover plate.

[0017] Further, positioning blocks are fixed on both sides of the top surfaces of the side plates and both sides of the top surfaces of the end plates. Positioning grooves adapted to the positioning blocks are formed on the surface of the blowing cover plate. After the blowing cover plate is connected to the sealing frame, the positioning blocks are located in the positioning grooves.

[0018] Further, pneumatic tensioning components are provided at both ends between the oppositely arranged side plates. The pneumatic tensioning components close the oppositely arranged side plates and end plates to squeeze and seal the upper end wall of the sand box.

[0019] Further, the pneumatic tensioning component includes a cylinder. The telescopic ends at both ends of the cylinder are rotatably connected with sliding seats. The sliding seats are fixedly connected with the side plates. One side of the sliding seat close to the end plate is an inclined surface. A sliding block with the same inclined surface as its inclined surface is arranged on the inclined surface of the sliding seat. The sliding block is fixedly connected with the end plate. A limiting block is fixed on the contact surface between the sliding block and the sliding seat. A limiting groove adapted to the limiting block is formed on the contact surface between the sliding seat and the sliding block. The limiting groove limits the limiting block to slide inside it. When the two sliding seats move towards each other, the inclined surfaces of the sliding seats squeeze the sliding blocks, and the sliding blocks squeeze the oppositely arranged end plates to move towards each other to seal the closing of the sand box.

[0020] Advantages of the present invention:

[0021] 1. The CO2 air-blowing hardening device for water glass sand of the present invention controls the compressor, the switch of the valve group, the pressure regulator, the online CO2 concentration tester and the PLC equipment through PLC, implements monitoring and process intelligent management of the compressor, cylinder, CO2 cylinder and recovered CO2 storage cylinder used in the device and the utilization of four process gases, thereby avoiding excessive CO2 charging, saving the amount of water glass added, recovering and reusing CO2 gas, reducing carbon emissions and CO2 consumption, ensuring the strength of the sand mold, facilitating sand falling and regeneration of old sand, and reducing the casting cost of the enterprise.

[0022] 2. The CO2 blowing and hardening device for water glass sand of the present invention sets a sealing frame on the periphery of the sand box. When blowing, the pneumatic tensioning assembly closes the relatively arranged side plates and end plates to squeeze and seal the sand box wall, thereby improving its connection sealing performance, avoiding the leakage of CO2 gas during the blowing process, further reducing the consumption of CO2, and ensuring that the CO2 concentration value of the sand box meets the standard, thereby ensuring the strength of the sand mold.

[0023] 3. The blowing hood of the CO2 blowing hardening device for water glass sand of the present invention is manually fastened to the sand box by a crane, relying on its own weight and pneumatic sealing, without the need for heavy physical labor, with a large and free range of movement, which is suitable for the characteristics of water glass sand with multiple floor shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of the device for CO2 air blowing hardening of water glass sand of the present invention;

[0025] Figure 2 This is a bottom view of the structure of the air blowing cover plate of the present invention;

[0026] Figure 3 This is a schematic diagram of the sealing frame structure from above according to the present invention;

[0027] Figure 4 This is a schematic side view of the sealing frame of the present invention;

[0028] Figure 5 The schematic diagram of the connection structure between the slider and the slide seat of the present invention Figure 1 ;

[0029] Figure 6 The schematic diagram of the connection structure between the slider and the slide seat of the present invention Figure 2 .

[0030] In the figure: 1. CO2 gas cylinder; 2. Recycled CO2 storage gas cylinder; 3. Compressor; 4. Mobile vehicle; 5. PLC device; 6. Gas circuit control valve group; 7. Blowing cover plate; 71. Air hole; 72. Gas cavity; 73. Positioning groove; 8. Counterweight; 9. Sealing frame; 91. Side plate; 92. End plate; 10. Sand box; 11. Sand mold; 12. Recycling bottom plate; 13. Sealing gasket; 14. CO2 on-line detector; 15. Pneumatic tensioning component; 16. Positioning block; 151. Cylinder; 152. Slide base; 153. Slide block; 1521. Limiting groove; 1531. Limiting block. Detailed implementation mode

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a middle element at the same time.

[0033] Embodiment

[0034] Please refer to Figure 1 As shown, the device for CO2 blowing hardening of sodium silicate sand in a foundry in this embodiment includes a CO2 gas cylinder 1, a recycled CO2 storage gas cylinder 2, a compressor 3, a blowing cover plate 7, a recycling bottom plate 12 and a sealing frame 9. The sealing frame 9 is hermetically sleeved on the outer top of the sand box 10. A sand mold 11 is arranged in the sand box 10. The blowing cover plate 7 is hermetically connected to the top of the sand box 10. The recycling bottom plate 12 is hermetically connected to the bottom end of the sand box (10). The blowing cover plate 7 is installed, connected and disassembled with the sand box 10 through a hoisting tool. Gas cavities 72 are opened in both the blowing cover plate 7 and the recycling bottom plate 12. A number of air holes 71 are opened in the sealed areas between the recycling bottom plate 12 and the sand box 10 and between the blowing cover plate 7 and the sand box 10. To ensure the uniform diffusion of the charged gas, a number of air holes 71 are opened on the surface of the gas cavity 72 in the sealed area, and the air holes 71 communicate with the gas cavity 72. As Figure 2 、 3 shown, the gas cavity 72 has good sealing performance and rigidity.

[0035] The air cavity 72 is communicated with the port of the CO2 gas cylinder 1, the port of the recovered CO2 storage gas cylinder 2, and the air outlet of the compressor 3 through connecting pipes. An air path control valve group 6 is connected to the connecting pipes. The air outlet of the compressor 3 is connected to the air path control valve group 6. Both the air path control valve group 6 and the compressor 3 are signal-connected to the PLC device 5. The PLC device 5 is used to control the opening and closing state of the air path control valve group 6 and the starting and stopping state of the compressor 3. The air path control valve group 6 includes a solenoid valve and a pressure regulating valve. To facilitate the movement of the blowing cover plate 7, the above-mentioned connecting pipes are all flexible hoses.

[0036] Please refer to Figure 3 、 4 As shown, the sealing frame 9 includes oppositely arranged side plates 91 and oppositely arranged end plates 92. The oppositely arranged end plates 92 are located between the oppositely arranged side plates 91. The two pairs of oppositely arranged side plates 91 and end plates 92 form a rectangular sealing frame 9 with an upper opening. The blowing cover plate 7 is arranged at the top opening of the sealing frame 9.

[0037] To facilitate the sealed connection between the sand box 10, the sealing frame 9, the blowing cover plate 7, and the recovery bottom plate 12, sealing gaskets 13 are provided in the contact areas between the sealing frame 9 and the sand box 10 (i.e., the contact areas between the side plates 91 and the sand box 10, and the contact areas between the end plates 92 and the sand box 10), the contact area between the recovery bottom plate 12 and the sand box 10, and the contact area between the blowing cover plate 7 and the sealing frame 9.

[0038] To increase the weight of the blowing cover plate 7 itself, a counterweight 8 is provided on the top of the blowing cover plate 7. The counterweight 8 increases the weight of the blowing cover plate 7 and enhances the downward pressure of the blowing cover plate 7.

[0039] To further improve the sealing performance of the sealing frame 9 against the wall of the sand box 10, pneumatic tensioning components 15 are provided at both the upper and lower ends between the oppositely arranged side plates 91. The pneumatic tensioning components 15 close the oppositely arranged side plates 91 and end plates 92, squeeze and seal the wall of the sand box 10, and improve its connection sealing performance.

[0040] Please refer to Figure 3 、 4As shown, the pneumatic tensioning assembly 15 includes a cylinder 151. The telescopic ends at both ends of the cylinder 151 are rotatably connected to sliding seats 152. The sliding seats 152 are fixedly connected to the side plates 91. One side of the sliding seat 152 close to the end plate 92 is an inclined surface. A slider 153 with the same inclined surface as its inclined surface is arranged on the inclined surface of the sliding seat 152. The slider 153 is fixedly connected to the end plate 92. The fixing of the sliding seat 152 to the side plate 91 and the fixing of the slider 153 to the end plate 92 are both fixed by bolts, which are not shown in the figure. A limiting block 1531 is fixed on the contact surface between the slider 153 and the sliding seat 152. A limiting groove 1521 adapted to the limiting block 1531 is formed on the contact surface between the sliding seat 152 and the slider 153. The limiting groove 1521 limits the limiting block 1531 to slide inside it. Specifically, the limiting block 1531 is a T-shaped block, and the limiting groove 1521 is a T-shaped groove adapted to the T-shaped block. The T-shaped block and the T-shaped groove cooperate with each other. As Figure 5 , 6 shown, the side plate 91 and the end plate 92 can be connected as a whole. When the two sliding seats 152 move towards each other, the slider 153 is squeezed through its inclined surface, and the opposite end plates 92 are squeezed by the slider 153 to move towards each other, and at the same time, the sand box 10 is closed, and the wall of the sand box 10 is squeezed and sealed.

[0041] To facilitate the docking of the blowing cover plate 7 and the sealing frame 9, positioning blocks 16 are fixed on both sides of the top surface of the side plate 91 and both sides of the top surface of the end plate 92. Positioning grooves 73 adapted to the positioning blocks 16 are formed on the surface of the blowing cover plate 7. When installing the blowing cover plate 7 on the top surface of the sealing frame 9, just align the positioning grooves 73 with the positioning blocks 16.

[0042] The above-mentioned cylinder 151 is signal-connected to the PLC device 5, and the PLC device 5 controls the telescopic state of the cylinder 151.

[0043] To facilitate the recovery of CO2 in the sand box 10 after the first type of blowing, the port of the CO2 recovery gas cylinder 2 is communicated with the air outlet of the compressor 3, and the air inlet of the compressor 3 is communicated with the air cavity 72 located in the recovery bottom plate 12.

[0044] To facilitate the movement of the CO2 gas cylinder 1, the CO2 recovery gas cylinder 2, and the compressor 3, the CO2 gas cylinder 1, the CO2 recovery gas cylinder 2, and the compressor 3 are arranged in the mobile vehicle 4, as Figure 1 shown.

[0045] To facilitate the monitoring of the CO2 concentration in the sand box 10, a CO2 on-line detector 14 is provided. The CO2 on-line detector 14 is communicated with the air cavity 72 in the recovery bottom plate 12. Specifically, the CO2 on-line detector 14 is installed on the gas path control valve group 6. The CO2 on-line detector 14 is signal-connected to the PLC device 5. The CO2 on-line detector 14 transmits the obtained CO2 concentration data to the PLC device 5 to monitor the blowing CO2 concentration. During recovery, the CO2 can also be recovered to the greatest extent according to the change value of the CO2 concentration value.

[0046] In this embodiment, the first type of blowing and purification process is as follows:

[0047] Preparation: Push the mobile cart 4 near the molding area, i.e., near the blowing box. Place the recovery bottom plate 12 on a flat area, connect all the gas pipeline, i.e., the connecting pipeline and the power line. Place the sand box 10 on the recovery bottom plate 12. The molded sand mold 11 is inside the sand box 10. Use a lifting tool to buckle the blowing cover plate 7 on the top opening of the sealing frame 9. The sealing frame 9 is sealed with the wall of the sand box 10 by the closing of the cylinder 151. Due to the gravity of the counterweight 8, the blowing cover plate 7 and the recovery bottom plate 12 are sealed with the top and bottom openings of the sand box 10.

[0048] Start of process execution:

[0049] Pre-set the parameters in the process, the CO2 concentration, i.e., the set values I, II, III, IV of the CO2 online detector 14. Control the solenoid valves and pressure regulating valves of each path of the gas path control valve group 6 through the PLC device 5 to ensure that the device supplies gas according to the process.

[0050] Before blowing, start the compressor 3 to apply negative pressure to the sand mold 11. The intake port of the compressor 3 and the recovery bottom plate 12 are connected through a solenoid valve. The solenoid valve connected to the outlet of the compressor 3 is opened to communicate with the external atmosphere. The compressor 3 inhales the air in the sand mold 11 and directly discharges it into the atmosphere to reduce the residual air in the sand mold 11 and ensure that the CO2 blown into the sand mold 11 quickly contacts and hardens with the sodium silicate in the sand mold 11.

[0051] When the set negative pressure time arrives, enter the blowing timing. The CO2 gas cylinder 1 is opened through the gas path control valve group 6, and after the pressure is adjusted by the corresponding pressure regulating valve, pure CO2 gas is supplied into the blowing cover plate 7 and blown into the sand mold 11. At this time, the compressor 3 is working and maintains negative pressure on the sand mold 11 until the CO2 online detector 14 installed on the recovery bottom plate 12 detects the CO2 concentration and reaches the set value I, then the gas supply of the CO2 gas cylinder 1 is closed and the compressor 3 is closed, and enter the set hardening time timing to avoid overblowing of CO2.

[0052] After the hardening time ends, the compressor 3 starts, and the negative pressure in the sand mold 11 is established again. The PLC device 5 controls the gas path control valve group 6 to open the solenoid valve at the outlet of the compressor 3 to the recovered CO2 storage cylinder 2, so that the outlet of the compressor 3 is connected to the port of the recovered CO2 storage cylinder 2. The compressor 3 inhales the CO2 tail gas in the sand mold 11, pressurizes it and stores it in the recovered CO2 storage cylinder 2. Until the CO2 online detector 14 detects that the concentration of CO2 reaches the set value II, the valve at the outlet of the compressor 3 to the recovered CO2 storage cylinder 2 is closed, the valve of the blowing cover plate 7 at the outlet of the compressor 3 is connected, and the inlet of the compressor 3 is connected to the atmosphere. Pure compressed air is blown into the sand mold 11 to discharge the remaining CO2 tail gas in the sand mold 11. Until the CO2 online detector 14 detects that the concentration of CO2 reaches the set value III, the purification time ends, and the blowing and purification of the first mold end.

[0053] When the blowing and purification of the first mold end, the CO2 used for blowing the first mold is recovered and reused, effectively reducing the consumption and emission of CO2, reducing environmental pollution, reducing casting costs, and controlling the gas path control valve group 6 and the compressor 3 by the PLC device 5 according to the detected CO2 concentration reaching the set value, realizing the automation of the CO2 blowing hardening process operation.

[0054] The blowing and purification process after the second mold is as follows:

[0055] The preliminary preparation is the same as that of the first mold. The PLC device 5 controls the gas path control valve group 6. Before blowing, the compressor 3 is started to apply negative pressure to the sand mold 11. The compressor 3 inhales the air in the sand mold 11 and the air chamber 72 and directly discharges it into the atmosphere.

[0056] After reaching the set negative pressure time, enter the blowing timing;

[0057] The solenoid valve connected to the port of the recovered CO2 storage cylinder 2 is opened, and the pressure is adjusted through the pressure regulating valve to supply the recovered CO2 gas into the blowing cover plate 7 and blow it into the sand mold 11. At this time, the compressor 3 is working and maintains the negative pressure on the sand mold 11 until the CO2 online detector 14 installed on the outlet pipeline of the recovery bottom plate 12 detects that the concentration of CO2 reaches the set value IV, the solenoid valve connected to the port of the recovered CO2 storage cylinder 2 is closed, and the solenoid valve connected to the port of the CO2 cylinder 1 is opened until the CO2 online detector 14 detects that the concentration of CO2 reaches the set value I, and the compressor 3 is turned off and starts to enter the hardening and standing time.

[0058] Enter the set hardening time timing;

[0059] After the hardening time ends, the compressor 3 starts, negative pressure is established in the sand mold 11, the solenoid valve from the air outlet of the compressor 3 to the recovered CO2 gas storage cylinder 2 is opened, the CO2 in the sand mold 11 is inhaled, and it is pressurized and stored in the recovered CO2 gas storage cylinder 2. Then, when the CO2 online detector 14 detects that the CO2 concentration reaches the set value II, the solenoid valve from the air outlet of the compressor 3 to the recovered CO2 gas storage cylinder 2 is closed, the valve connecting the outlet of the compressor 3 to the blowing cover plate 7 is connected and the inlet of the compressor 3 is connected to the atmosphere, and pure compressed air is blown into the sand mold 11 to discharge the residual CO2 tail gas in the sand mold 11. Until the CO2 online detector 14 detects that the CO2 concentration reaches the set value III, the purification process ends, the blowing and purification of the second type end, and thereafter the sand mold 11 is all executed according to the second type process.

[0060] As described above, the set values (I, II, III, IV) for measuring the CO2 detection concentration are input as 5 after being verified according to the on-site conditions, and can be adjusted and reset in real time to ensure the purity of the recovered CO2. When vacuumizing the negative pressure of the sand mold 11 and purifying the tail gas, excessive CO2 emissions are avoided, and at the same time, the CO2 blowing time is prevented from being too long to affect the production rhythm, and big data for the future is formed and recorded in the memory.

[0061] Furthermore, the working process of the sodium silicate sand CO2 blowing hardening device is described. The processes of blowing, purifying and recovering include the following steps:

[0062] After the pneumatic seal sealing frame 9 is sealed, the blowing, purifying and recovering processes start. The PLC device 5 controls the timing as follows:

[0063] Time sequence (seconds) Control purpose Control target Actuator Type I start 0 Compressor on Compressor motor on PLC 0^10 Sand mold evacuated Compressor inlet valve open, outlet valve open to atmosphere Valve group 10^X Provide pure CO2 gas to the blowing hood CO2 valve open, CO2 enters the blowing hood Valve group X Online detected concentration set value I Set value I: Represents that the sand mold is filled with CO2 gas Valve group X^X + 30 Hardening wait for 30 seconds CO2 valve closed ×+30^Y Purify the sand mold Compressor outlet connected to the blowing hood Valve group Y^Z Recover CO2 gas into the storage tank Compressor outlet valve connected to the CO2 recovery storage tank Z Valve group Online detected concentration set value II Set value II: The CO2 gas content in the sand mold is too low PLC Z^Q Stop CO2 recovery Q Compressor outlet valve connected to the atmosphere Online detected concentration set value III Set value III: The sand mold contains extremely low CO2 PLC Type I process ends 0 System stops 0^10 Type II starts Compressor on Compressor motor on 10^H PLC Sand mold evacuated Compressor inlet valve open, outlet valve open to atmosphere Valve group H^H + M Hardening with recovered CO2 gas Recovered CO2 gas cylinder valve open, recovered CO2 enters the blowing Valve group H + M Online detected concentration set value IV Set value IV: The recovered CO2 is full PLC H + M^N Hardening with pure CO2 gas Recovered CO2 gas cylinder closed, pure CO2 gas cylinder valve open N Valve group Online detected concentration set value I Set value I: Represents that the sand mold is filled with CO2 gas N+30 PLC Hardening wait for 30 seconds CO2 valve closed Valve group N + 30^P Purify the sand mold Compressor outlet connected to the blowing hood Valve group P^S Recover CO2 gas into the storage tank Compressor outlet valve connected to the CO2 recovery storage tank S Valve group Online detected concentration set value II Set value II: The CO2 gas content in the sand mold is too low PLC S^R Stop CO2 recovery Compressor outlet valve connected to the atmosphere R Valve group Online detected concentration set value III Set value III: The sand mold contains extremely low CO2 PLC Type II process ends System stops, Repeat the Type II process after Type II

[0064] The sodium silicate sand CO2 blowing hardening device of the present invention is controlled by a PLC. By controlling the compressor, the opening and closing of the valve group 6, the pressure regulator, the online CO2 concentration tester 14 and the PLC device 5, the use of the compressor 3, the cylinder 151, the CO2 gas cylinder 1, the recovered CO2 gas storage cylinder 2 and the four process gases in the device is monitored and the process is intelligently managed, avoiding excessive CO2 charging and overblowing, that is, saving the amount of sodium silicate added, reducing the consumption and emission of CO2, solving the collapsibility, ensuring the strength of the sand mold 11, facilitating the regeneration of used sand, and reducing the casting cost of the enterprise.

[0065] The above four process gases include: pure CO2 gas, compressed air, negative pressure gas and collected CO2. The pure CO2 comes from the CO2 gas cylinder 1 or a large gas tank, the compressed air and the negative pressure gas come from the compressor 3, and the recovered CO2 gas comes from the recovered CO2 gas storage cylinder 2.

[0066] The difficulty in regenerating the above sand mold 11 is related to the large amount of sodium silicate added. The reasons for increasing the amount of sodium silicate are the low strength and slow hardening of the sand mold. Taking the sodium silicate CO2 hardening process as an example, the low strength of the sand mold is not caused by the low amount of sodium silicate added, but by other reasons. In the sodium silicate sand blowing CO2 method, due to the lack of good time control, the blowing time is long, that is, too much CO2 is blown into the sodium silicate, resulting in the decrease rather than the increase of the sand mold strength. The present invention monitors the CO2 concentration in the sand mold to control the CO2 blowing time, and timely blows compressed air to displace the residual CO2 gas in the sand core mold, which can effectively prevent the overblowing of sodium silicate sand. Moreover, the present invention solves the problems of CO2 overblowing and CO2 emission, realizes low addition amount of sodium silicate binder, high strength, renewable reuse of used sand, and can partially replace resin sand, which is beneficial to environmental protection and cost reduction, and has wide application value in the casting industry.

[0067] The device for hardening sodium silicate sand by blowing CO2 has a huge potential market. There are thousands of foundries using the sodium silicate sand process in our country. Among the 5.5 - 6 million tons of steel castings produced annually, about 30% still use the method of hardening sodium silicate sand by blowing CO2. Every year, more than 500,000 tons of ordinary sodium silicate are consumed in the method of hardening sodium silicate sand by blowing CO2. Because of the improper blowing process, this process consumes a large amount of sodium silicate, causes difficulties in shakeout and regeneration of used sand, and about 8 million tons of waste sand are discharged every year, wasting silica sand resources, polluting the environment, and increasing the cost of new sand input.

[0068] The problems existing in CO2 sodium silicate sand are clear, that is, the improper blowing process causes a high addition amount of sodium silicate, poor collapsibility, and difficulty in regenerating used sand. The fundamental reason is that the correct blowing method and prevention of overblowing have not been mastered. This system will create an intelligent means for foundries hardening sodium silicate sand with CO2, standardize and intelligentize the blowing process, that is, save the addition amount of sodium silicate, reduce the consumption and emission of CO2. Importantly, it solves the two major problems of collapsibility and regeneration, which is of great significance.

[0069] According to the latest theory, overblowing in the CO2 hardening method of sodium silicate sand is the root cause of the poor performance of sodium silicate sand, and the sodium silicate addition amount is as high as 5% to 8%. The high sodium silicate addition amount is the fundamental reason for the poor collapsibility of sodium silicate sand. For every 1% reduction in the sodium silicate addition amount, the sand removal working hours for castings can be saved by about 50%. The sand removal working hours for castings with a sodium silicate addition amount of 4% is 25% of that with an addition amount of 6%. Through this system, it is strived to control the sodium silicate addition amount within 5%, a reduction of 3% compared to the existing addition amount. Calculated based on 30% of 5.5 million tons of castings per year for sodium silicate sand, with a sand-to-iron ratio of 5:1, the sand consumption is 8.25 million tons. Saving 3% of sodium silicate is 247,500 tons; saving and reducing CO2 is calculated at 400 L of CO2 gas per cubic meter of sand mold / approximately 785 grams, which is 4,170 tons; reducing the discharged waste sand and saving new sand, based on an annual discharge of 5 million tons of waste sand with a regeneration and reuse rate of 90%, is 4.5 million tons. This will bring about an economic benefit of approximately 1.5 billion yuan and an environmental protection contribution to the entire casting industry. According to the market demand of 2,000 sets and a selling price of 100,000 yuan per set, the total market amount is approximately 200 million yuan.

[0070] It should be noted that in this article, if there are relationship terms such as first and second, etc., they are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitations, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for CO2 blowing hardening of sodium silicate sand in a foundry, characterized in that, Including: A recycling bottom plate (12), which is hermetically connected to the bottom end of the sand box (10); A blowing cover plate (7), which is hermetically connected to the top end of the sand box (10); A sealing frame (9), which is hermetically sleeved on the outer top of the sand box (10); An air cavity (72) and a plurality of air holes (71). The air cavity (72) is respectively arranged in the recycling bottom plate (12) and the blowing cover plate (7). The plurality of air holes (71) are respectively opened in the sealed area between the recycling bottom plate (12) and the sand box (10) and in the sealed area between the blowing cover plate (7) and the sand box (10), and the air holes (71) are communicated with the air cavity (72). The air cavity (72) is communicated with the port of the CO2 gas cylinder (1), the port of the recycled CO2 gas storage cylinder (2), and the air inlet of the compressor (3) through connecting pipes and an air path control valve group (6). The air outlet of the compressor (3) is connected to the air path control valve group (6). The air path control valve group (6) and the compressor (3) are both signal-connected to the PLC device (5); The sealing frame (9) includes oppositely arranged side plates (91) and oppositely arranged end plates (92). The oppositely arranged end plates (92) are located between the oppositely arranged side plates (91). The oppositely arranged side plates (91) and end plates (92) form a sealing frame (9) with an open upper end. The blowing cover plate (7) is arranged at the top opening of the sealing frame (9); Sealing gaskets (13) are arranged in the contact area between the sealing frame (9) and the sand box (10), the contact area between the recycling bottom plate (12) and the sand box (10), and the contact area between the blowing cover plate (7) and the sealing frame (9); Pneumatic tensioning components (15) are arranged at both ends between the oppositely arranged side plates (91). The pneumatic tensioning components (15) close the oppositely arranged side plates (91) and end plates (92) to squeeze and seal the upper end wall of the sand box (10); The pneumatic tensioning component (15) includes a cylinder (151). The telescopic ends at both ends of the cylinder (151) are rotatably connected with sliding seats (152). The sliding seats (152) are fixedly connected with the side plates (91). One side of the sliding seat (152) close to the end plate (92) is an inclined surface. A sliding block (153) with the same inclined surface as the inclined surface of the sliding seat (152) is arranged on the inclined surface of the sliding seat (152). The sliding block (153) is fixedly connected with the end plate (92). A limiting block (1531) is fixed on the contact surface between the sliding block (153) and the sliding seat (152). A limiting groove (1521) adapted to the limiting block (1531) is opened on the contact surface between the sliding seat (152) and the sliding block (153). The limiting groove (1521) limits the limiting block (1531) to slide inside it. When the two sliding seats (152) move towards each other, the sliding block (153) is squeezed by their inclined surfaces, and the sliding block (153) squeezes the oppositely arranged end plates (92) to move towards each other to close the sand box (10).

2. The device for CO2 blowing hardening of sodium silicate sand in a foundry according to claim 1, characterized in that: A CO2 online detector (14) is communicated with the air cavity (72) in the recycling bottom plate (12). The CO2 online detector is signal-connected to the PLC device (5). The CO2 online detector (14) is installed on the air path control valve group (6).

3. The device for CO2 blowing hardening of sodium silicate sand in a foundry according to claim 2, characterized in that: The gas path control valve group (6) includes a solenoid valve and a pressure regulating valve.

4. A device for CO2 blowing hardening of sodium silicate sand in a foundry according to claim 3, characterized in that: The port of the CO2 gas cylinder (1), the outlet of the compressor (3), and the port of the recycled CO2 gas cylinder (2) are communicated with the air cavity (72) located in the blowing cover plate (7). The inlet of the compressor (3) is communicated with the air cavity (72) located in the recycling bottom plate (12). The outlet of the compressor (3) is communicated with the port of the recycled CO2 gas cylinder.

5. A device for CO2 blowing hardening of sodium silicate sand in a foundry according to claim 4, characterized in that: A counterweight (8) is arranged on the top of the blowing cover plate (7).

6. The device for CO2 blowing hardening of sodium silicate sand in a foundry according to claim 5, characterized in that: Positioning blocks (16) are fixed on both sides of the top surface of the side plate (91) and both sides of the top surface of the end plate (92). Positioning grooves (73) adapted to the positioning blocks (16) are formed on the surface of the blowing cover plate (7). After the blowing cover plate (7) is connected to the sealing frame (9), the positioning blocks (16) are located in the positioning grooves (73).

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