A production process for lost foam casting

Abstract

The application relates to a production process of an expendable pattern casting, and belongs to the technical field of casting. The production process comprises the following steps: sequentially performing bottom sand adding, filling sand adding and surface sand adding on a molding conveying line through a sand adding system; the sand adding system comprises a bottom sand adding unit, a filling sand adding unit and a surface sand adding unit; the sand adding speed of the bottom sand adding unit is greater than the reference value of the sand adding speed of the filling sand adding unit, and the reference value of the sand adding speed of the filling sand adding unit is greater than the sand adding speed of the surface sand adding unit; the sand boxes with completed molding are shunted to at least two parallel pouring conveying belts; the multiple sand boxes are synchronously poured on the parallel pouring conveying line; and the sand is recycled after pouring. The three-stage speed gradient setting of the bottom sand adding unit, the filling sand adding unit and the surface sand adding unit realizes the optimization of the production line rhythm under the premise of guaranteeing the model integrity, solves the imbalance problem of insufficient box supply in the molding section after the pouring speed is increased, and further improves the overall production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of casting, in particular to a production process of lost foam casting. BACKGROUND

[0002] As a modern precision casting process, lost foam casting is formed by burying a foam model into a dry sand mold cavity, and then pouring molten metal under negative pressure to replace the gasified model. Although this technology can achieve near-net-shape forming of complex components, the bottleneck of production line efficiency has existed for a long time.

[0003] To break through the capacity limit of traditional single-line pouring, the existing scheme such as multi-pouring conveying line layout, through parallel pouring stations, makes the same pouring equipment process multiple sand boxes at the same time, which significantly shortens the pouring process time. However, this kind of improvement of one-sidedly strengthening the pouring link exposes the serious lag of the molding process. Because the strength of the foam model is very low, especially the thin-walled structure is easily collapsed by the high-speed sand flow during sand filling, forcing the production side to reduce the sand filling speed to protect the model. This "shape protection and speed reduction" operation makes the molding time become the short board of the whole line rhythm: when the parallel pouring line processes sand boxes at high speed, the molding section cannot keep up with the supply of sand boxes due to cautious sand filling, resulting in idle pouring stations. Even worse, to coordinate the capacity, the molding is forced to speed up, which causes the model to be crushed and the mold cavity to be loose, etc. The crux of the problem is that the current technology only focuses on single-point optimization of pouring efficiency, without understanding the essential contradiction between "model protection" and "sand filling speed" in the molding process, and without breaking through the speed regulation dilemma of the sand filling process itself. SUMMARY

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

[0005] The production process of lost foam casting provided by the present application adopts the following technical scheme:

[0006] A production process of lost foam casting, comprising the following steps:

[0007] S1, sequentially performing bottom sand adding, sand filling adding and surface sand adding on the molding conveying line through a sand adding system;

[0008] The sand adding system comprises a bottom sand adding unit, a sand filling adding unit and a surface sand adding unit;

[0009] The sand adding speed of the bottom sand adding unit is greater than the reference value of the sand adding speed of the sand filling adding unit, and the reference value of the sand adding speed of the sand filling adding unit is greater than the sand adding speed of the surface sand adding unit;

[0010] S2, the sand boxes with completed molding are divided into at least two parallel pouring conveying belts;

[0011] S3, synchronously implementing pouring on the parallel pouring conveying lines for the plurality of sand boxes;

[0012] S4, recycling the sand after pouring.

[0013] By adopting the technical scheme, the three-stage speed gradient of the bottom sand adding unit, the sand filling adding unit and the surface sand adding unit is set, the line beat optimization is realized under the premise of ensuring the model integrity, the high-speed sand laying of the bottom sand station and the ultra-low-speed sand covering of the surface sand station are complementary and efficient, and the imbalance problem of the whole line caused by the insufficient sand boxes in the molding section after the pouring speed is increased in the traditional lost foam production line is solved.

[0014] Optionally, in the step S1, the bottom sand adding unit is used for laying a basic sand layer, the sand filling adding unit is used for filling a model main body, and the surface sand adding unit is used for covering a model top sealing layer.

[0015] Optionally, in the step S1, the sand filling adding unit is classified and speed-regulated according to the height coordinates of the fragile area obtained through finite element analysis, and specifically includes the following steps.

[0016] S1a, pre-generating a height coordinate set of fragile points: calculating the positions where the stress exceeds a threshold under the impact of sand flow through an ANSYS / ABAQUS simulation model, and outputting height coordinate values thereof;

[0017] S1b, real-time height monitoring: online detecting a filling height during sand filling;

[0018] S1c, accurately triggering speed reduction: when the real-time height deviates from the pre-stored height coordinate by ≤±1 mm, the sand output speed is stepwise reduced to a set safety value.

[0019] By adopting the technical scheme, the height coordinates of the fragile area are pre-judged based on finite element analysis, the stepwise speed reduction is triggered through real-time height monitoring, the speed control of the sand filling adding unit is upgraded from experience driving to data driving, and the contradiction between the protection of the internal thin-walled structure and the filling efficiency is simultaneously solved.

[0020] Optionally, after the step S1c, the following step is further included.

[0021] S1d, speed recovery mechanism: after the fragile area is filled, the sand output speed of the sand filling adding unit is linearly recovered to a reference value within 3 seconds.

[0022] By adopting the technical scheme, the speed recovery mechanism is added, the sand filling adding unit is linearly recovered to the reference value within 3 seconds after the fragile area is filled, the control blind area after the speed reduction protection is filled, and the secondary damage of the speed mutation to the sand layer stability or the line beat is avoided.

[0023] Optionally, the sand filling and adding unit comprises a hopper, a control bucket arranged at the bottom outlet of the hopper, and a filling height on-line detector arranged on the side wall of the control bucket.

[0024] The filling height on-line detector is used to obtain the height coordinate of the sand layer top surface in the sand box in real time, the filling height on-line detector is signal connected with a control module, and a speed regulating execution mechanism is arranged in the control bucket and signal connected with the control module.

[0025] By arranging the filling height on-line detector on the side wall of the control bucket, a closed loop is formed with the speed regulating execution mechanism in the control bucket and the control module, which provides a hardware basis for triggering the speed reduction of the sand outlet speed of the sand filling and adding unit, and eliminates the signal delay error caused by indirect detection.

[0026] Optionally, the speed regulating execution mechanism comprises a movable aperture plate and a fixed aperture plate, the movable aperture plate is arranged above the fixed aperture plate, the fixed aperture plate is fixed in the control bucket, and an array of fixed apertures is arranged on the surface of the fixed aperture plate; the movable aperture plate is provided with movable apertures which are identical in shape, size and array arrangement mode to the fixed apertures.

[0027] The movable aperture plate is driven to move horizontally by a driver, so that the movable apertures are relatively dislocated from the fixed apertures, and the overlapping area of the movable apertures and the fixed apertures is changed to realize the regulation of the effective flow area of the sand flow.

[0028] By adopting the above technical scheme, the movable aperture plate is located above the fixed aperture plate and directly contacts the bottom layer of the sand material, when the movable aperture plate moves horizontally, the top surface of the movable aperture plate generates a shearing force on the sand material, breaks the bonding force between the sand particles, and simultaneously eliminates the arching phenomenon on the surface of the aperture plate; the horizontal dislocation mechanism makes the flow area monotonously change with the displacement amount, and the control linearity is guaranteed by the optimized design of the shape of the through hole, so as to guarantee the control accuracy and response speed of the sand filling and adding unit under the condition of frequent speed change.

[0029] Optionally, a long slot is arranged on the first side wall of the control bucket, the second side wall is located on the opposite side of the first side wall, the movable aperture plate can extend out of the control bucket through the long slot during displacement, a notch area is arranged on the side of the movable aperture plate close to the driver, and a sealing baffle connected with the second side wall of the control bucket is arranged above the notch area.

[0030] When the movable aperture plate is displaced to a fully closed state, one side of the movable aperture plate extends out of the control bucket, and the other side of the movable aperture plate is completely exposed to the inner cavity of the control bucket, at this time, the sealing baffle shields the notch area.

[0031] When the movable aperture plate is displaced to a fully open state, one side of the movable aperture plate is embedded in the long slot or extends out of the control bucket, and the other side of the movable aperture plate abuts against the second side wall of the control bucket to form a limiting position.

[0032] By adopting the technical scheme, the structure of the control bucket extending out of the right side of the movable hole plate breaks through the limitation of the stroke of the bin body, increases the effective displacement, meets the displacement speed regulation requirement, and realizes full-stroke leakage prevention through the static sealing design of the gap area and the sealing baffle.

[0033] Optionally, the top surface of the movable hole plate is provided with an arch breaking piece.

[0034] By adopting the technical scheme, the arch breaking piece on the top surface of the movable hole plate synchronously breaks the arching of the sand during the displacement process, forms a functional integration with the speed regulation execution mechanism, eliminates the sand bridging while regulating the speed, and reduces the manual unblocking intervention.

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

[0036] 1. By setting three-stage speed gradient of the bottom sand adding unit, the sand filling adding unit and the surface sand adding unit, the high-speed laying of the base sand layer in the initial casting stage improves the efficiency, the medium-speed balancing in the model filling stage balances the efficiency and safety, and the final ultra-low-speed precise covering of the model top. On the premise of ensuring the integrity of the model, the line beat optimization is realized, the high-speed sand laying of the bottom sand station and the ultra-low-speed sand laying of the surface sand station are complementary, the imbalance problem of the whole line caused by insufficient box supply in the molding section after the pouring speed is increased in the traditional lost foam production line is solved, and the overall production efficiency of the production line is improved;

[0037] 2. Based on the finite element simulation prediction of the model mechanical fragile point height coordinate, when the sand box is filled with sand by the sand filling adding unit, the millimeter-level matching trigger step speed reduction of the real-time height monitoring and the preset coordinate is triggered, so that the high-speed sand flow is switched to the preset safety value before contacting the fragile area. This mechanism upgrades the traditional experience-driven control to data-driven control, especially for the internal thin-walled structure that is blocked, the simulation model can analyze the stress concentration area that cannot be detected by manual detection, further reducing the possibility of damage to the fragile area of the model during the sand filling process. In addition, the efficiency loss caused by global speed reduction is avoided.

[0038] 3. By performing linear recovery of the speed after the fragile area is filled, the risk of sudden change of speed after step speed reduction is eliminated. The linear incremental process makes the sand flow rise smoothly, avoids the secondary impact on the loose sand layer that has just covered the fragile area caused by sudden speed increase, and accurately matches the demand of the conveying line beat. This speed recovery mechanism fills the control blind area after speed reduction protection, forms a complete closed loop of "early warning - speed reduction - recovery", and ensures that the total sand filling time of each sand box is stable and controllable. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a whole flow chart of a production process of the lost foam casting of the embodiment of the present application.

[0040] Figure 2is a flow chart for classifying and regulating the sand discharging speed of the sand filling and adding unit in the embodiment of the application.

[0041] Figure 3 is a structural schematic diagram of the sand adding system and the pouring conveying line in the embodiment of the application.

[0042] Figure 4 is a structural schematic diagram of the sand filling and adding unit in the embodiment of the application.

[0043] Figure 5 is a sectional view of the internal structure of the sand filling and adding unit in the embodiment of the application.

[0044] Figure 6 is a control principle diagram of the control module in the embodiment of the application.

[0045] Figure 7 is Figure 5 is a local enlarged schematic view of A in FIG.

[0046] Legend: 1, sand adding system; 11, bottom sand adding unit; 12, sand filling and adding unit; 121, silo; 122, regulating hopper; 1221, long slot; 1222, sealing baffle; 123, filling height on-line detector; 124, control module; 13, surface sand adding unit; 2, pouring conveying line; 3, speed regulating execution mechanism; 31, movable aperture plate; 311, movable aperture; 312, arch breaking piece; 32, fixed aperture plate; 321, fixed aperture; 33, driver; 331, connecting lug. DETAILED DESCRIPTION

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

[0048] Embodiment:

[0049] The embodiment of the application discloses a production process of lost foam casting. Referring to Figure 1 and Figure 2 The production process of lost foam casting comprises the following steps:

[0050] S1, sequentially performing bottom sand adding, sand filling and adding and surface sand adding on the molding conveying line by the sand adding system 1;

[0051] S2, distributing the sand boxes with completed molding to at least two parallel pouring conveying lines 2;

[0052] S3, synchronously implementing pouring on the parallel pouring conveying lines 2;

[0053] S4, recycling the molding sand after pouring and recycling.

[0054] In step S1, the sand adding system 1 comprises a bottom sand adding unit 11, a filling sand adding unit 12 and a surface sand adding unit 13; wherein the bottom sand adding unit 11 is used for laying a base sand layer, the filling sand adding unit 12 is used for filling a model main body, and the surface sand adding unit 13 is used for covering a model top sealing layer. The sand discharging speed of the bottom sand adding unit 11 is greater than a reference value of the sand discharging speed of the filling sand adding unit 12, and the reference value of the sand discharging speed of the filling sand adding unit 12 is greater than the sand discharging speed of the surface sand adding unit 13.

[0055] In the present application, the bottom sand adding unit 11 establishes a high-stability base support layer to avoid model displacement; the filling sand adding unit 12 adaptively fills the model main body contour to ensure no dead angle in a complex cavity; and the surface sand adding unit 13 forms a dense sealing layer at an ultralow speed to eliminate the risk of vacuum leakage. Through the three-stage speed gradient setting of the bottom sand adding unit 11, the filling sand adding unit 12 and the surface sand adding unit 13, the base sand layer is laid at a high speed in the initial casting stage to improve efficiency, the model is filled at a medium speed in the model filling stage to balance efficiency and safety, and the model top is finally covered precisely at an ultralow speed. On the premise of ensuring the integrity of the model, the production line beat optimization is realized, the high-speed sand laying of the bottom sand station and the ultralow-speed sand covering of the surface sand station are complementary and efficient, the whole-line imbalance problem of the traditional lost foam production line due to insufficient box supply in the molding section after pouring speed-up is solved, and the overall production efficiency of the production line is improved.

[0056] Referring to Figures 1-3 In step S1, the sand discharging speed of the filling sand adding unit 12 is classified and regulated according to the height coordinates of the fragile area obtained by finite element analysis, specifically including:

[0057] S1a, pre-generate fragile point height coordinate set: calculate the position where the stress exceeds the threshold under sand flow impact through ANSYS / ABAQUS simulation model, and output the height coordinate value;

[0058] S1b, real-time height monitoring: online detection of filling height during sand filling;

[0059] S1c, accurate triggering of speed reduction: when the real-time height deviates from the pre-stored height coordinate by ≤±1mm, the sand discharging speed is stepped down to a set safety value;

[0060] S1d, speed recovery mechanism: after the fragile area is filled, the sand discharging speed of the filling sand adding unit 12 is linearly restored to the reference value within 3 seconds.

[0061] Before the production of the lost foam casting, the height coordinate of the mechanical fragile point of the prediction model is determined based on the finite element simulation. The millimeter-level matching of the real-time height monitoring and the preset coordinate triggers the stepwise speed reduction, so that the high-speed sand flow is switched to a safe speed before contacting the fragile area. This mechanism upgrades the traditional experience-driven control to data-driven control. Especially for the internal thin-walled structure that is blocked (such as the internal cavity of the engine water jacket), the simulation model can analyze the stress concentration area that cannot be detected by artificial exploration, realizing the leap from macro damage prevention to micro stress dissipation. After the filling of the fragile area is completed, the speed is linearly restored to eliminate the risk of sudden change of speed after stepwise speed reduction. The linear incremental process makes the sand flow kinetic energy rise smoothly, avoids the secondary impact of sudden speed-up on the loose sand layer that has just covered the fragile area, and accurately matches the demand of the conveying line rhythm. This speed recovery mechanism fills the control blind area after speed reduction protection, forms a complete closed loop of "early warning-reduction-recovery", avoids the efficiency loss caused by global speed reduction during the sand filling process, and ensures the stable and controllable total sand filling time of each sand box.

[0062] With reference to Figures 4-6 , the sand filling and adding unit 12 comprises a bunker 121, a control hopper 122 fixed at the bottom outlet of the bunker 121, and a filling height on-line detector 123 installed on the side wall of the control hopper 122. The filling height on-line detector 123 is used to obtain the height coordinate of the sand layer top surface in the sand box in real time. The filling height on-line detector 123 is signal connected with a control module 124. The control hopper 122 is provided with a speed regulation execution mechanism 3, and the speed regulation execution mechanism 3 is signal connected with the control module 124. In this way, the filling height on-line detector 123 is integrated on the side wall of the control hopper 122, so that the detection path avoids the interference of the sand flow, guarantees the authenticity of the height data, and directly collects the height coordinate of the sand layer top surface and transmits it to the control module 124, to form real-time linkage with the speed regulation execution mechanism 3, guarantee the stable implementation of step S1c, and eliminate the signal delay error caused by indirect detection.

[0063] With reference to 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 side wall of the regulating hopper 122 is provided with a long slot 1221, and the second side wall is located on the opposite side of the first side wall. The movable aperture plate 31 can extend out of the regulating hopper 122 through the long slot 1221 during displacement. The side of the movable aperture plate 31 close to the driver 33 is provided with a notch area, and the notch area is covered by a sealing baffle 1222 connected to the second side wall of the regulating hopper 122. When the movable aperture plate 31 is displaced to the fully closed state, one side of the movable aperture 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 shielding the notch area. When the movable aperture plate 31 is displaced to the fully open state, one side of the movable aperture plate 31 is embedded in the long slot 1221 or extends out of the regulating hopper 122, and the other side of the movable aperture plate 31 abuts against the inner wall of the second side wall of the regulating hopper 122 to form a limiting position. In this way, the structure that the right side of the movable aperture plate 31 can extend out of the regulating hopper 122 breaks through the limitation of the stroke of the bin body, increases the effective displacement, meets the displacement speed regulation requirement, and provides a clearance for the movement of the movable aperture plate 31. On the other hand, the area above the notch area is always covered by the sealing baffle 1222, and the closed leak-proof state is maintained in the full stroke of the movable aperture plate 31. When the movable aperture plate 31 is in the fully closed state, the side far away from the notch area of the movable aperture plate 31 extends out of the long slot 1221, so that the movable aperture plate 31 and the hole position of the fixed aperture plate 32 are maximally dislocated, and the sand flow is completely cut off. When the movable aperture plate 31 is in the fully open state, the side close to the notch area of the movable aperture plate 31 abuts against the inner wall of the second side wall of the regulating hopper 122 to form a mechanical hard limit, thereby avoiding overshoot damage.

[0067] The implementation principle of the production process of the lost foam casting provided in the embodiment of the application is as follows: through the three-stage speed gradient setting of the bottom sand adding unit 11, the sand filling adding unit 12 and the surface sand adding unit 13, the high-speed laying of the base sand layer is adopted in the initial stage of casting to improve the efficiency, the medium-speed laying is adopted in the model filling stage to balance the efficiency and safety, and the ultra-low-speed precise covering of the top of the model is finally adopted. The line beat optimization is realized on the premise of guaranteeing the integrity of the model, the high-speed sand laying of the bottom sand station and the ultra-low-speed sand laying of the surface sand station are complementary, the problem of imbalance of the whole line caused by the insufficient supply of the molding section after the pouring speed is increased in the traditional lost foam production line is solved, and the overall production efficiency of the production line is improved.

[0068] Based on the finite element simulation, the height coordinate of the mechanical fragile point of the model is predicted, when the sand box is filled with sand by the sand filling adding unit 12, the millimeter-level matching trigger stepwise speed reduction of the real-time height monitoring and the preset coordinate is triggered, so that the high-speed sand flow is switched to the preset safety value before contacting the fragile area. The mechanism upgrades the traditional experience-driven control to data-driven control, especially for the internal thin-walled structure that is blocked, the simulation model can analyze the stress concentration area that cannot be detected by artificial, and the possibility of damage of the fragile area of the model in the sand filling process is further reduced. In addition, the efficiency loss caused by the global speed reduction is avoided.

[0069] After the fragile zone filling is completed, the speed linear recovery is performed to eliminate the risk of sudden speed change after the stepwise speed reduction. The linear increasing process makes the sand flow gently rise, avoids the secondary impact on the loose sand layer just covered by the fragile zone due to the sudden speed increase, and accurately matches the demand of the conveying line beat. This speed recovery mechanism fills the control blind area after the speed reduction protection, forms a complete closed loop of "early warning - speed reduction - recovery", and ensures that the total filling time of each sand box is stable and controllable.

[0070] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope 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. Recycle and reuse molding sand after casting; 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. 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.

2. The production process of lost foam casting according to claim 1, 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.

3. The production process of lost foam casting according to claim 1, 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).

4. The production process of lost foam casting according to claim 3, 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.

5. The production process of lost foam casting according to claim 4, 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).

6. The production process of lost foam casting according to claim 5, characterized in that: The top surface of the moving perforated plate (31) is provided with an arch-breaking piece (312).

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