Production process for lost foam casting

Abstract

The invention relates to a production process for lost foam casting, which belongs to the technical field of casting and comprises the following steps: sequentially adding bottom sand, filling and adding sand and adding surface sand on a molding conveying line through a sand adding system; the sand adding system comprises a bottom sand adding unit, a sand filling and adding unit and a surface sand adding unit; the sand outlet speed of the bottom sand adding unit is larger than the reference value of the sand outlet speed of the sand filling and adding unit, and the reference value of the sand outlet speed of the sand filling and adding unit is larger than the sand outlet speed of the surface sand adding unit. Distributing the molded sand box to at least two pouring conveying belts connected in parallel; synchronously pouring the plurality of sand boxes on a parallel pouring conveying line; and after pouring, the molding sand is recycled and recycled. Through the three-stage speed gradient arrangement of the bottom sand adding unit, the sand filling and adding unit and the surface sand adding unit, production line rhythm optimization is achieved on the premise that the integrity of the model is guaranteed, the unbalance problem of insufficient box supply of a molding section after pouring is accelerated is solved, and then the overall production efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of casting, and in particular to a production process for lost foam casting. Background Technology

[0002] Lost foam casting, a modern precision casting process, involves embedding a foam model in a dry sand cavity and pouring molten metal under negative pressure to replace the vaporized model, thus forming the casting. While this technology can achieve near-net-shape forming of complex components, production line efficiency bottlenecks have long existed.

[0003] To overcome the capacity limitations of traditional single-line casting, existing solutions, such as multi-line casting layouts, use parallel casting stations to allow the same casting equipment to process multiple sand boxes simultaneously, significantly shortening the casting process time. However, this one-sided improvement in the casting process has exposed a serious lag in the molding process. Due to the extremely low strength of foam models, especially thin-walled structures, they are highly susceptible to collapse under the impact of high-speed sand flow during molding and sand filling, forcing manufacturers to reduce the sand filling speed to preserve the model. This "shape preservation and deceleration" operation makes molding time a bottleneck in the overall line's cycle time: when parallel casting lines process sand boxes at high speed, the molding section, due to cautious sand filling, cannot supply enough boxes, resulting in idle casting stations waiting. Even worse, forcibly accelerating molding to coordinate capacity leads to a chain of defects such as model crushing and loose cavities. The crux of the problem is that current technology only focuses on optimizing casting efficiency at a single point, failing to understand the essential contradiction between "model protection" and "sand filling speed" in the molding process, and failing to solve the speed control dilemma inherent in the sand filling process itself. Summary of the Invention

[0004] In order to overcome the imbalance between molding efficiency and pouring efficiency in lost foam casting and thus improve the overall production efficiency of the production line, this application provides a lost foam casting production process.

[0005] This application provides a lost foam casting production process, which adopts the following technical solution:

[0006] A lost foam casting production process includes the following steps:

[0007] S1. On the molding conveyor line, the bottom sand, filling sand, and surface sand are added sequentially through the sand adding system.

[0008] The sand adding system includes a bottom sand adding unit, a fill sand adding unit, and a surface sand adding unit;

[0009] The sand discharge rate of the bottom sand adding unit is greater than the reference value of the sand discharge rate of the filling sand adding unit, and the reference value of the sand discharge rate of the filling sand adding unit is greater than the sand discharge rate of the surface sand adding unit.

[0010] S2. Divert the shaped sand box to at least two parallel pouring conveyor belts;

[0011] S3. Simultaneous pouring of multiple sand boxes on parallel pouring and conveying lines;

[0012] S4. The molding sand is recovered and recycled after casting.

[0013] By adopting the above technical solution, and through the three-level speed gradient setting of the bottom sand adding unit, the filling sand adding unit, and the surface sand adding unit, the production line cycle is optimized while ensuring the integrity of the model. This allows the high-speed sand laying at the bottom sand station and the ultra-low-speed sand covering at the surface sand station to complement each other and enhance the efficiency, thus solving the problem of overall line imbalance in traditional lost foam production lines due to insufficient supply of molded boxes after the casting speed is increased.

[0014] Optionally, in step S1, the bottom sand adding unit is used to lay the base sand layer, the filling sand adding unit is used to fill the main body of the model, and the top sand adding unit is used to cover the top sealing layer of the model.

[0015] Optionally, in step S1, the sand discharge rate of the sand-filling unit is adjusted in stages according to the height coordinates of the vulnerable area obtained from finite element analysis, specifically including:

[0016] S1a, Pre-generated set of vulnerable point height coordinates: Calculate the location where the stress exceeds the threshold under sand flow impact using the ANSYS / ABAQUS simulation model, and output its height coordinate values;

[0017] S1b, Real-time height monitoring: Online detection of filling height during sand filling process;

[0018] S1c, Precise Triggering Speed ​​Reduction: When the deviation between the real-time height and the pre-stored height coordinates is ≤±1mm, the sand output speed is reduced to the set safety value in a stepwise manner.

[0019] By adopting the above technical solution, the height coordinates of vulnerable areas are predicted based on finite element analysis, and step-by-step deceleration is triggered by real-time height monitoring. This upgrades the speed control of the sand filling unit from experience-driven to data-driven, simultaneously resolving the contradiction between the protection of the internal thin-walled structure and the filling efficiency.

[0020] Optionally, the method may further include the following after step S1c:

[0021] S1d, Speed ​​Recovery Mechanism: After the fragile area is filled, the sand discharge speed of the sand filling and sand adding unit linearly recovers to the baseline value within 3 seconds.

[0022] By adopting the above technical solution, the speed recovery mechanism is added so that the sand filling unit linearly recovers the baseline value within 3 seconds after filling the fragile area, filling the control blind spot after the speed reduction protection, and avoiding secondary damage to the stability of the sand layer or the production line cycle caused by sudden speed changes.

[0023] Optionally, the sand filling and sand adding unit includes a silo, a regulating hopper located at the bottom outlet of the silo, and an online filling height detector located on the side wall of the regulating hopper;

[0024] The online filling height detector is used to obtain the height coordinates of the top surface of the sand layer in the sand box in real time. The online filling height detector is connected to a control module. The regulating hopper is equipped with a speed regulating actuator, which is connected to the control module.

[0025] By adopting the above technical solution, an online filling height detector is installed on the side wall of the regulating hopper, forming a closed loop with the speed regulating actuator and control module inside the regulating hopper. This provides a hardware basis for the speed reduction triggering of the sand filling and sand adding unit, and eliminates the signal delay error caused by indirect detection.

[0026] Optionally, the speed regulating actuator includes a moving hole plate and a fixed hole plate, with the moving hole plate fitted above the fixed hole plate. The fixed hole plate is fixed inside the regulating hopper, and its surface is provided with an array of fixed holes. The moving hole plate is provided with moving holes that are exactly the same in shape, size and array arrangement as the fixed holes.

[0027] The moving orifice plate is driven to move laterally by a driver, causing the moving orifice and the fixed orifice to be relatively misaligned. By changing the overlapping area of ​​the moving orifice and the fixed orifice, the effective flow area of ​​the sand flow can be controlled.

[0028] By adopting the above technical solution, the moving orifice plate is located above the fixed orifice plate and directly contacts the bottom layer of sand. When the moving orifice plate moves laterally, its top surface generates shear force on the sand, breaking the adhesion between sand particles and simultaneously eliminating the arching phenomenon on the surface of the orifice plate. The lateral misalignment mechanism makes the flow area change monotonically with the displacement, and the optimized design of the through hole shape ensures the linearity of control, ensuring the control accuracy and response speed of the sand filling and sand adding unit under frequent speed change conditions.

[0029] Optionally, the first side wall of the control bucket is provided with an elongated groove, and the second side wall is located on the opposite side of the first side wall. The moving orifice plate can extend out of the control bucket through the elongated groove during displacement. The moving orifice plate has a notch area on the side near the driver, and a sealing baffle connected to the second side wall of the control bucket is covered above the notch area.

[0030] When the moving orifice plate is moved to the fully closed state, one side of it extends out of the control bucket, and the notch area on the other side is completely exposed to the inner cavity of the control bucket. At this time, the sealing baffle keeps the notch area covered.

[0031] When the moving orifice plate is displaced to the fully open state, one side of it is embedded in the elongated groove or extends out of the regulating hopper, while the other side of the moving orifice plate forms an abutment limit with the second side wall of the regulating hopper.

[0032] By adopting the above technical solution, the structure in which the regulating bucket can extend from the right side of the moving orifice plate breaks through the limitation of the hopper on the stroke, increases the effective displacement, meets the displacement speed regulation requirements, and achieves full-stroke leakage prevention through the static sealing design of the notch area and the sealing baffle.

[0033] Optionally, the top surface of the moving perforated plate is provided with an arch-breaking plate.

[0034] By adopting the above technical solution, the arch-breaking plate on the top surface of the moving orifice plate simultaneously breaks up the sand arch during the displacement process, forming a functional integration with the speed regulating actuator. This eliminates sand bridging while regulating speed, reducing manual intervention for clearing blockages.

[0035] In summary, this application includes at least one of the following beneficial technical effects:

[0036] 1. By setting a three-level speed gradient through the bottom sand adding unit, the filling sand adding unit, and the top sand adding unit, the high-speed laying of the basic sand layer at the beginning of casting improves efficiency, the medium speed balances efficiency and safety during the model filling stage, and finally the top of the model is precisely covered at an ultra-low speed. This optimizes the production line cycle time while ensuring model integrity, allowing the high-speed sand laying at the bottom sand station and the ultra-low speed sand covering at the top sand station to complement each other and increase efficiency. This solves the problem of overall line imbalance in traditional lost foam production lines due to insufficient box supply in the molding section after pouring speed increases, thereby improving the overall production efficiency of the production line.

[0037] 2. This application uses finite element simulation to predict the height coordinates of mechanically vulnerable points in the model. During sand filling in the sand box, real-time height monitoring and millimeter-level matching with preset coordinates trigger a stepped deceleration, causing the high-speed sand flow to switch to a preset safe value before contacting the vulnerable area. This mechanism upgrades traditional experience-driven control to data-driven control. Especially for obscured internal thin-walled structures, the simulation model can analyze stress concentration areas that are undetectable by humans, further reducing the possibility of damage to vulnerable areas during sand filling. Furthermore, it simultaneously avoids efficiency losses caused by overall deceleration.

[0038] 3. By performing linear speed recovery after the vulnerable area is filled, the risk of sudden speed changes after stepped deceleration is eliminated. The linear increase process allows the sand kinetic energy to recover smoothly, avoiding secondary impacts on the loose sand layer that has just covered the vulnerable area due to sudden acceleration, while precisely matching the conveyor line's cycle time requirements. This speed recovery mechanism fills the control blind spot after deceleration protection, forming a complete closed loop of "early warning-deceleration-recovery," ensuring that the total filling time of each sand box is stable and controllable. Attached Figure Description

[0039] Figure 1 This is an overall flow chart of a lost foam casting production process according to an embodiment of this application.

[0040] Figure 2This is a flowchart illustrating the graded speed adjustment of the sand discharge rate of the sand filling and sand adding unit in the embodiments of this application.

[0041] Figure 3 This is a structural schematic diagram illustrating the sand-adding system and the pouring conveyor line in the embodiments of this application.

[0042] Figure 4 This is a schematic diagram illustrating the overall structure of the sand filling and sand adding unit in the embodiments of this application.

[0043] Figure 5 This is a cross-sectional view illustrating the internal structure of the sand filling and sand adding unit in the embodiments of this application.

[0044] Figure 6 This is a control principle diagram illustrating the control module in the embodiments of this application.

[0045] Figure 7 yes Figure 5 A magnified view of a portion of point A in the middle.

[0046] Explanation of reference numerals in the attached drawings: 1. Sand feeding system; 11. Bottom sand feeding unit; 12. Filling sand feeding unit; 121. Hopper; 122. Control hopper; 1221. Long trough; 1222. Sealing baffle; 123. Online filling height detector; 124. Control module; 13. Top sand feeding unit; 2. Pouring conveyor line; 3. Speed ​​regulating actuator; 31. Moving orifice plate; 311. Moving orifice; 312. Arch breaking plate; 32. Fixed orifice plate; 321. Fixed orifice; 33. Driver; 331. Connecting lug. Detailed Implementation

[0047] The following combination Figures 1-7 This application will be described in further detail below.

[0048] Example:

[0049] This application discloses a production process for lost foam casting. (Refer to...) Figure 1 and Figure 2 A lost foam casting production process includes the following steps:

[0050] S1. On the molding conveyor line, the sand adding system 1 sequentially adds bottom sand, fill sand, and surface sand.

[0051] S2. Divert the completed sand box to at least two parallel pouring lines 2;

[0052] S3. Simultaneously pouring sand into multiple sand boxes on the parallel pouring and conveying line 2;

[0053] S4. The molding sand is recovered and recycled after casting.

[0054] In step S1, the sand adding system 1 includes a bottom sand adding unit 11, a filling sand adding unit 12, and a top sand adding unit 13; wherein, the bottom sand adding unit 11 is used to lay the base sand layer, the filling sand adding unit 12 is used to fill the main body of the model, and the top sand adding unit 13 is used to cover the top sealing layer of the model. The sand discharge rate of the bottom sand adding unit 11 is greater than the reference value of the sand discharge rate of the filling sand adding unit 12, and the reference value of the sand discharge rate of the filling sand adding unit 12 is greater than the sand discharge rate of the top sand adding unit 13.

[0055] In this application, the bottom sand adding unit 11 establishes a highly stable foundation support layer to prevent model placement displacement; the filling sand adding unit 12 adaptively fills the model's main contour, ensuring no dead corners in complex cavities; and the surface sand adding unit 13 forms a dense sealing layer at ultra-low speed, thereby eliminating the risk of vacuum leakage. Through the three-level speed gradient setting of the bottom sand adding unit 11, the filling sand adding unit 12, and the surface sand adding unit 13, high-speed laying of the foundation sand layer improves efficiency in the initial casting stage, medium speed balances efficiency and safety in the model filling stage, and finally, ultra-low speed precisely covers the top of the model. This optimizes the production line cycle time while ensuring model integrity, allowing the high-speed sand laying at the bottom sand station and the ultra-low-speed sand covering at the surface sand station to complement each other, solving the problem of overall line imbalance in traditional lost foam production lines due to insufficient box supply in the molding section after casting speed increases, thereby improving the overall production efficiency of the production line.

[0056] Reference Figures 1-3 In step S1, the sand discharge rate of the sand filling and sand adding unit 12 is adjusted in stages according to the height coordinates of the vulnerable area obtained from finite element analysis, specifically including:

[0057] S1a, Pre-generated set of vulnerable point height coordinates: Calculate the location where the stress exceeds the threshold under sand flow impact using the ANSYS / ABAQUS simulation model, and output its height coordinate values;

[0058] S1b, Real-time height monitoring: Online detection of filling height during sand filling process;

[0059] S1c, Precise Triggering Speed ​​Reduction: When the deviation between the real-time height and the pre-stored height coordinates is ≤±1mm, the sand output speed is reduced to the set safety value in a stepwise manner;

[0060] S1d, Speed ​​Recovery Mechanism: After the fragile area is filled, the sand discharge speed of the sand filling and sand adding unit 12 linearly recovers to the baseline value within 3 seconds.

[0061] Before lost foam casting production, the height coordinates of mechanically vulnerable points in the model are predicted based on finite element simulation. Real-time height monitoring and millimeter-level matching with preset coordinates trigger a stepped speed reduction, ensuring the high-speed sand flow switches to a safe speed before contacting the vulnerable area. This mechanism upgrades traditional experience-driven control to data-driven control, especially for obscured thin-walled structures (such as the engine water jacket cavity). The simulation model can analyze stress concentration areas that are undetectable by humans, achieving a leap from macroscopic damage prevention to microscopic stress relief. After the vulnerable area is filled, linear speed recovery is performed, eliminating the risk of sudden speed changes after stepped speed reduction. The linear increase process allows the sand flow energy to recover smoothly, avoiding secondary impacts on the loose sand layer that has just covered the vulnerable area due to sudden acceleration, while precisely matching the conveyor line's cycle time requirements. This speed recovery mechanism fills the control blind spot after speed reduction protection, forming a complete closed loop of "early warning-speed reduction-recovery," avoiding efficiency losses caused by speed reduction throughout the sand filling process, and ensuring that the total filling time of each sand box is stable and controllable.

[0062] Reference Figures 4-6 The sand filling and adding unit 12 includes a hopper 121, a regulating hopper 122 fixed to the bottom outlet of the hopper 121, and an online filling height detector 123 installed on the side wall of the regulating hopper 122. The online filling height detector 123 is used to obtain the height coordinates of the top surface of the sand layer in the sand box in real time. The online filling height detector 123 is connected to a control module 124. The regulating hopper 122 is equipped with a speed regulating actuator 3, which is also connected to the control module 124. In this way, by integrating the online filling height detector 123 on the side wall of the regulating hopper 122, the detection path avoids sand flow interference, ensuring the authenticity of the height data. It also directly collects the height coordinates of the top surface of the sand layer and transmits them to the control module 124, forming a real-time linkage with the speed regulating actuator 3, ensuring the stable implementation of step S1c and eliminating signal delay errors caused by indirect detection.

[0063] Reference Figure 6 and Figure 7The speed regulating actuator 3 includes a moving orifice plate 31 and a fixed orifice plate 32. The fixed orifice plate 32 is fixed to the inner wall of the outlet end of the regulating hopper 122, and its surface is provided with an array of fixed orifices 321. The moving orifice plate 31 is fitted above the fixed orifice plate 32, and the moving orifice plate 31 is slidably connected to the inner wall of the regulating hopper 122. The moving orifice plate 31 is provided with moving orifices 311 that are exactly the same in shape, size and array arrangement as the fixed orifices 321. An actuator 33 is installed on the outer wall of the regulating hopper 122. The actuator 33 and the output end of the control module actuator 33 are fixed with connecting ears 331. The connecting ears 331 extend into the regulating hopper 122 and are fixed to one side of the moving orifice plate 31. The actuator 33 is signal connected to the control module 124. The moving orifice plate 31 is driven to move laterally by the actuator 33, so that the moving orifice 311 and the fixed orifice 321 are relatively misaligned. By changing the overlapping area of ​​the moving orifice 311 and the fixed orifice 321, the effective flow area of ​​the sand flow is regulated.

[0064] In this application, the moving orifice plate 31 is located above the fixed orifice plate 32 and directly contacts the bottom layer of sand. When the moving orifice plate 31 moves laterally to adjust the effective flow area of ​​the sand flow, its top surface generates a shear force on the sand, breaking the adhesion between sand particles. This simultaneously eliminates the arching phenomenon on the surface of the orifice plate while regulating the sand discharge speed of the sand filling and adding unit 12. The lateral misalignment mechanism makes the flow area change monotonically with the displacement, and the optimized design of the through-hole shape ensures the linearity of control, guaranteeing the control accuracy and response speed of the sand filling and adding unit 12 under frequent speed change conditions. In this embodiment, the moving orifice 311 and the fixed orifice 321 are rectangular holes. This ensures that the effective flow area of ​​the sand flow and the displacement of the moving orifice plate 31 maintain a strict linear relationship, avoiding nonlinear compensation calculations, thereby simplifying the control algorithm and improving the response speed.

[0065] Reference Figure 5 and Figure 7 Multiple anti-bridging plates 312 are fixed on the top surface of the moving orifice plate 31. To reduce motion resistance, the length direction of the anti-bridging plates 312 is the same as the displacement direction of the moving orifice plate 31. When adjusting the sand discharge speed of the sand filling and adding unit 12, the anti-bridging plates 312 on the top surface of the moving orifice plate 31 cut into the bottom of the sand layer with the displacement, simultaneously breaking up the sand arch and guiding the sand particles near the anti-bridging plates 312 to flow towards the orifice 311. This forms a functional integration with the speed regulating actuator 3, eliminating sand bridging while regulating speed and reducing manual intervention for clearing blockages.

[0066] Reference Figure 5 and Figure 7The first sidewall of the regulating hopper 122 is provided with an elongated groove 1221, and the second sidewall is located on the opposite side of the first sidewall. During displacement, the moving orifice plate 31 can extend out of the regulating hopper 122 through the elongated groove 1221. The side of the moving orifice plate 31 near the driver 33 is provided with a notch area, and a sealing baffle 1222 connected to the second sidewall of the regulating hopper 122 covers the notch area. When the moving orifice plate 31 is moved to the fully closed state, one side of the moving orifice plate 31 extends out of the regulating hopper 122, and the notch area on the other side is completely exposed to the inner cavity of the regulating hopper 122. At this time, the sealing baffle 1222 keeps the notch area covered. When the moving orifice plate 31 is moved to the fully open state, one side of the moving orifice plate 31 is embedded in the elongated groove 1221 or extends out of the regulating hopper 122, while the other side of the moving orifice plate 31 forms an abutment limit with the inner wall of the second sidewall of the regulating hopper 122. Thus, the structure of the regulating bucket 122 extending from the right side of the moving orifice plate 31 overcomes the limitation of the silo body on the stroke, increases the effective displacement, and meets the displacement speed regulation requirements. The notch area provides a basis for the movement of the moving orifice plate 31, and the area above the notch area is always covered by the sealing baffle 1222, maintaining a closed and leak-proof seal throughout the entire stroke of the moving orifice plate 31. In the fully closed state, the side of the moving orifice plate 31 away from the notch area extends a long groove 1221, maximizing the misalignment between the orifice positions of the moving orifice plate 31 and the fixed orifice plate 32, completely cutting off the sand flow. In the fully open state, the side of the moving orifice plate 31 near the notch area abuts against the inner wall of the second side wall of the regulating bucket 122, forming a mechanical hard limit to avoid over-rush damage.

[0067] The implementation principle of the lost foam casting production process in this application embodiment is as follows: Through a three-level speed gradient setting of the bottom sand adding unit 11, the filling sand adding unit 12, and the top sand adding unit 13, high-speed laying of the base sand layer improves efficiency at the initial casting stage; medium speed balances efficiency and safety during the model filling stage; and finally, ultra-low speed precision covers the top of the model. This optimizes the production line cycle time while ensuring model integrity, allowing the high-speed sand laying at the bottom sand station and the ultra-low-speed sand covering at the top sand station to complement and enhance each other. This solves the problem of overall line imbalance in traditional lost foam casting production lines due to insufficient box supply in the molding section after casting speed increases, thereby improving the overall production efficiency of the production line.

[0068] This application, based on finite element simulation to predict the height coordinates of mechanically vulnerable points in the model, triggers a stepped deceleration during sand filling in the sand box by real-time height monitoring and millimeter-level matching with preset coordinates. This ensures that the high-speed sand flow switches to a preset safe value before contacting the vulnerable area. This mechanism upgrades traditional experience-driven control to data-driven control. Especially for obscured internal thin-walled structures, the simulation model can analyze stress concentration areas that are not detectable manually, further reducing the possibility of damage to vulnerable areas of the model during sand filling. In addition, it simultaneously avoids efficiency loss caused by deceleration across the entire area.

[0069] After the vulnerable area is filled, a linear speed recovery is performed to eliminate the risk of sudden speed changes after a stepped deceleration. The linear increase process allows the sand kinetic energy to recover smoothly, avoiding secondary impacts on the loose sand layer that has just covered the vulnerable area due to sudden acceleration, while precisely matching the conveyor line's cycle time requirements. This speed recovery mechanism fills the control blind spot after the deceleration protection, forming a complete closed loop of "early warning-deceleration-recovery," ensuring that the total filling time of each sand box is stable and controllable.

[0070] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A production process for lost foam casting, characterized in that, Includes the following steps: S1. On the molding conveyor line, the bottom sand, filling sand and surface sand are added sequentially through the sand adding system (1); The sand adding system (1) includes a bottom sand adding unit (11), a filling sand adding unit (12), and a surface sand adding unit (13); The sand discharge rate of the bottom sand adding unit (11) is greater than the reference value of the sand discharge rate of the filling sand adding unit (12), and the reference value of the sand discharge rate of the filling sand adding unit (12) is greater than the sand discharge rate of the surface sand adding unit (13). S2. Divert the completed sand box to at least two parallel pouring lines (2); S3. Simultaneous pouring of multiple sand boxes on a parallel pouring and conveying line (2); S4. The molding sand is recovered and recycled after casting.

2. The production process of lost foam casting according to claim 1, characterized in that: In step S1, the bottom sand adding unit (11) is used to lay the base sand layer, the sand filling unit (12) is used to fill the main body of the model, and the top sand adding unit (13) is used to cover the top sealing layer of the model.

3. The production process of lost foam casting according to claim 2, characterized in that: In step S1, the sand discharge rate of the sand filling and sand adding unit (12) is adjusted in stages according to the height coordinates of the vulnerable area obtained from finite element analysis, specifically including: S1a, Pre-generated set of vulnerable point height coordinates: Calculate the location where the stress exceeds the threshold under sand flow impact using the ANSYS / ABAQUS simulation model, and output its height coordinate values; S1b, Real-time height monitoring: Online detection of filling height during sand filling process; S1c, Precise Triggering Speed ​​Reduction: When the deviation between the real-time height and the preset height coordinates is ≤±1mm, the sand output speed is reduced to the preset safety value in a stepwise manner.

4. The production process of lost foam casting according to claim 3, characterized in that, The process after step S1c also includes: S1d, speed recovery mechanism: After the fragile area is filled, the sand discharge speed of the sand filling and sand adding unit (12) is linearly restored to the reference value within 3 seconds.

5. The production process of lost foam casting according to claim 3, characterized in that: The sand filling and sand adding unit (12) includes a hopper (121), a regulating hopper (122) located at the bottom outlet of the hopper (121), and an online filling height detector (123) located on the side wall of the regulating hopper (122); The online filling height detector (123) is used to obtain the height coordinates of the top surface of the sand layer in the sand box in real time. The online filling height detector (123) is connected to the control module (124). The regulating bucket (122) is equipped with a speed regulating actuator (3). The speed regulating actuator (3) is connected to the control module (124).

6. The production process of lost foam casting according to claim 5, characterized in that: The speed regulating actuator (3) includes a moving hole plate (31) and a fixed hole plate (32), and the moving hole plate (31) is attached to the top of the fixed hole plate (32). The fixed hole plate (32) is fixed in the regulating bucket (122), and its surface is provided with an array of fixed holes (321). The moving hole plate (31) is provided with moving holes (311) that are exactly the same as the fixed holes (321) in shape, size and array arrangement. The moving plate (31) is driven to move laterally by the driver (33), so that the moving hole (311) and the fixed hole (321) are relatively misaligned. By changing the overlapping area of ​​the moving hole (311) and the fixed hole (321), the effective flow area of ​​sand flow can be controlled.

7. The production process of lost foam casting according to claim 6, characterized in that: The first side wall of the regulating bucket (122) is provided with an elongated groove (1221), and the second side wall is located on the opposite side of the first side wall. During the displacement process, the moving orifice plate (31) can extend out of the regulating bucket (122) through the elongated groove (1221). The moving orifice plate (31) has a notch area on the side near the driver (33), and the notch area is covered with a sealing baffle (1222) connected to the second side wall of the regulating bucket (122). When the moving orifice plate (31) is moved to the fully closed state, one side of it extends out of the regulating bucket (122), and the notch area on the other side is completely exposed to the inner cavity of the regulating bucket (122). At this time, the sealing baffle (1222) keeps the notch area covered. When the moving orifice plate (31) is moved to the fully open state, one side of it is embedded in the elongated groove (1221) or extends out of the regulating bucket (122), while the other side of the moving orifice plate (31) forms an abutment limit with the second side wall of the regulating bucket (122).

8. The production process of lost foam casting according to claim 6, characterized in that: The top surface of the moving perforated plate (31) is provided with an arch-breaking piece (312).

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