A supergravity test sand model automatic sand pouring device and automatic sand pouring method

Abstract

The application discloses an automatic sand pouring device and method for supergravity test sand soil model, and relates to the technical field of geotechnical engineering model preparation. The device comprises a three-axis mechanical arm, a sand pouring mechanism, a sand box, an electric control system and a real-time monitoring system. A program of a preset sand pouring track is written in the electric control system, the three-axis mechanical arm is controlled to drive the sand pouring mechanism to walk along the preset sand pouring track and pour sand layer by layer above the sand box, and the real-time monitoring system provides real-time data feedback, so that the electric control system automatically adjusts the sand pouring track according to the actual situation, realizes the layer-by-layer programmed automatic pouring of sand soil in the sand soil model preparation process, and further improves the sand pouring uniformity. The application solves the problem that the subsequent model saturation effect is directly affected by the manual sand pouring method due to insufficient experience of the operator and uneven sand pouring, reduces the influence of the sand soil model quality on a series of problems such as mechanical response, and is suitable for geotechnical engineering model preparation.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering model preparation technology, specifically to an automatic sand pouring device and method for a supergravity test sand model. Background Technology

[0002] Automatic sand-pouring devices primarily serve heavy-duty aircraft and model preparation machines. The preparation of models for four major experimental chambers—slope and high dam, geotechnical and earthquake engineering, deep-sea engineering, and deep-earth engineering and environment—all require automatic sand-pouring devices. Sample preparation is a fundamental and crucial step in the experimental process. Sand sample preparation is mainly controlled by relative density. Common sand sample preparation methods include vibration, compaction, tamping, and sand rain methods. Sand pouring is a key step in preparing sand models for ultragravity experiments, and the sand rain method is commonly used. The basic principle of the sand rain method is to convert the gravitational potential energy of sand particles into kinetic energy. Utilizing the impact and collision between sand particles, the particles are rearranged to achieve a certain density. The method typically involves placing air-dried sand into a container with a sand outlet under ground gravity. A lifting device is used to raise the container, and the distance between the sand outlet and the model box is adjusted, allowing the sand particles to fall freely into the model box while simultaneously moving the outlet at a certain speed, creating a relatively uniform sand layer within the model box. The relative density of a sand model is related to factors such as the drop height of the sand pouring nozzle, the moving speed of the nozzle, its shape, and its size. Currently, the commonly used manual sand pouring method is greatly affected by the operator's experience. Uneven sand pouring will directly affect the subsequent saturation effect of the model, and thus affect the mechanical response of the model. An automatic sand pouring device can solve this problem well. Summary of the Invention

[0003] The automatic sand pouring device achieves fully automatic three-dimensional motion through a programmable logic controller (PLC controller), reducing errors caused by manual operation and obtaining sand model samples with good uniformity and repeatability. Moreover, by changing the sand pouring control factors, it can successfully prepare sand models with a relative density between 0.2 and 0.9, including loose sand samples. At the same time, it is convenient to apply to large-scale model experiments, especially centrifuge model experiments.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: An automatic sand pouring device for a supergravity test sand model includes a three-axis robotic arm, a sand pouring mechanism, a sand box, an electrical control system, and a real-time monitoring system, which realizes the programmed automatic pouring of sand layer by layer and real-time data feedback during the sand model preparation process.

[0005] The three-axis robotic arm and the sand box are both fixed to the ground. The sand pouring mechanism is fixed to the lower end of the three-axis robotic arm. The three-axis robotic arm drives the sand pouring mechanism to perform layer-by-layer sand pouring operations above the sand box according to the preset sand pouring path. The sand pouring mechanism includes a sand storage tank, a rotary feeding valve, and an adapter nozzle connected sequentially from top to bottom. The sand storage tank is loaded with sand to be poured. The rotary feeding valve has multiple sets of blades inside, which divide the valve cavity into multiple sand storage chambers. During the pouring process, the blades rotate at a constant speed, ensuring that the amount of sand stored in each sand storage chamber is consistent, thereby guaranteeing a consistent pouring speed. The opening of the adapter nozzle can be adjusted to control the sand flow rate and drop point. The electrical control system adopts a bus motion servo control system, which designs the sand pouring path and the traveling speed of the sand pouring mechanism, and completes motion control through a PLC controller program; The real-time monitoring system acquires the real-time weight of the remaining sand in the sand storage tank and the real-time height displacement of the sand in the sand box, and transmits the data to the electrical control system. The electrical control system calculates the relative density of the single-layer sand pouring based on the real-time weight of the remaining sand in the sand storage tank and the real-time height displacement of the sand in the sand box, and automatically adjusts the sand pouring path, sand drop height, sand pouring mechanism travel speed and the opening of the matching nozzle according to the relative density of the single-layer sand pouring, so as to obtain a sand model that meets the target relative density.

[0006] Preferably, the three-axis robotic arm includes two X-axis travel rails, two support columns, a Y-axis, a Z-axis, an X-axis drive system, and a Y-axis and Z-axis drive system. The two X-axis travel rails are fixedly installed on the ground, and the two support columns form sliding pairs with the two X-axis travel rails respectively. A Y-axis is fixed above the support columns, and the center of the Y-axis is connected to the Z-axis. A sand-casting mechanism is fixed at the lower end of the Z-axis. A Y-axis and Z-axis drive mechanism is provided at the connection between the Y-axis and the Z-axis. An X-axis drive mechanism is provided at the bottom of the support columns. The X-axis drive mechanism and the Y-axis drive system are composed of a servo motor and a planetary reducer with a large reduction ratio. The Z-axis drive mechanism is composed of a servo motor and a worm gear reducer with a large reduction ratio.

[0007] Preferably, the sand-pouring mechanism is fixed to the lower end of the Z-axis of the three-axis robotic arm.

[0008] Preferably, the sand storage tank is equipped with multiple pneumatic vibrators that act on the sand storage tank to break the arched structure that appears during the feeding process and maintain the flow of sand.

[0009] Preferably, the method for calculating the relative density of the single-layer sand pouring is as follows: the mass of the single-layer sand pouring is calculated based on the change in the weight of the remaining sand in the sand storage bucket during layer-by-layer pouring. The volume of a single sand layer is obtained by combining the sand density. The depth of a single sand layer is calculated based on the displacement of the sand material in the sand box during layer-by-layer pouring. The average porosity of a single-layer sand-cast layer was calculated from this. : ; in, Specific gravity of sand refers to the ratio of the mass of sand to the mass of an equal volume of pure water at 4°C, and is dimensionless. This is the density of water, expressed in kg / m³. 3 ; The dry density of each layer of sand, in kg / m³ 3 ; This represents the total mass of the poured sand material, expressed in kg. This refers to the total volume of the poured sand, expressed in cubic meters (m³). 3 ; This is the effective length of the sand box, in meters. This represents the effective width of the sandbox, in meters. Then, based on the average porosity The relative density D is obtained r : ; in, Maximum void ratio refers to the void ratio of sand in its loosest state; Minimum void ratio refers to the void ratio of sand in its most compact arrangement.

[0010] The present invention also provides an automatic sand pouring method based on the aforementioned automatic sand pouring device for a high-gravity test sand model, comprising the following steps: S1. Determine the opening of the appropriate nozzle and the travel speed of the sand pouring mechanism based on the target relative density, and design the sand pouring path in combination with the sand particle size, and write the corresponding control program into the electrical control system. S2. The electrical control system controls the three-axis robotic arm to drive the sand pouring mechanism to move along the designed sand pouring path to the material replenishment station to load sand. After loading is completed, the electrical control system controls the sand pouring mechanism to move to the sand pouring station and reach the preset sand drop height. S3. The blades of the rotary discharge valve begin to rotate, causing the sand to be poured in the sand storage tank to be uniformly transported to the matching nozzle and flow out from the nozzle opening into the sand box. At the same time, the electrical control system controls the three-axis robotic arm to drive the sand pouring mechanism to pour layer by layer according to the designed sand pouring path. During the pouring process, the real-time monitoring system obtains the real-time remaining sand mass in the sand storage tank and the real-time sand height displacement in the sand box, and transmits the data to the electrical control system. The electrical control system calculates the relative density of a single sand pouring layer based on this data, and automatically adjusts the sand pouring path, sand drop height, sand pouring mechanism travel speed and matching nozzle opening according to the relative density to obtain a sand model that meets the target relative density. S4. When the remaining sand in the sand storage tank reaches the preset threshold, the electrical control system records the location of the sand pouring mechanism at this time, and controls the three-axis robotic arm to drive the sand pouring mechanism to the replenishment station to replenish sand through the fixed-point replenishment tank or the screw feeder. After the replenishment is completed, it returns to the recorded position and continues to pour sand layer by layer according to the predetermined design trajectory until the pouring is completed.

[0011] Compared with the prior art, the present invention has the following advantages: (1) The automatic sand pouring device provided by the present invention realizes fully automatic three-dimensional motion through a programmable logic controller (PLC controller), which reduces manual operation, reduces the labor intensity of operators, and reduces the impact of manual operation on the uniformity of sand pouring. (2) By changing the sand pouring trajectory, sand drop height, sand pouring mechanism travel speed and nozzle opening through program control, sand samples with different loose states can be successfully prepared, and sand model samples with relative density between 0.2 and 0.9 can be prepared. (3) The real-time monitoring system detects the flatness of the sand pouring surface in real time, calculates and adjusts the relative density of the sand pouring layer in real time, and ensures that the relative density error of each sand pouring layer is ≤5%, thereby obtaining a sand model sample with good uniformity. (4) Due to the high operating accuracy of the three-axis robotic arm, it can obtain sand model samples with good repeatability. Attached Figure Description

[0012] Figure 1 : Front view of the overall structure of the invention; Figure 2 Side view of the overall structure of the present invention; Figure 3 : Axonometric view of the overall structure of the invention; Figure 4 Schematic diagram of a three-axis robotic arm; Figure 5 Axonometric view of a three-axis robotic arm; Figure 6 Schematic diagram of the sand pouring mechanism; Figure 7 Axonometric drawing of the sand-pouring mechanism; Figure 8 Schematic diagram of nozzle opening adjustment structure.

[0013] The components include: 1. Three-axis robotic arm; 2. Sand pouring mechanism; 3. Screw feeder; 4. Electrical control system; 5. Dust collector; 6. Sand box; 7. X-axis travel guide rail; 8. Support column; 9. Y-axis; 10. Z-axis; 11. X-axis drive mechanism; 12. Y-axis and Z-axis drive mechanism; 13. Sand storage tank; 14. Sand storage tank connecting pipe; 15. Adaptive nozzle; 16. Rotary discharge valve; 17. Pneumatic vibrator; 18. Weighing sensor; 19. Radar level gauge; 20. Nozzle housing; 21. Opening adjustment seat; 22. Opening adjustment plate. Detailed Implementation

[0014] The present invention will be further described below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0015] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0016] Figure 1 , Figure 2 and Figure 3 The invention demonstrates an automatic sand pouring device for a supergravity test sand model. The device uses a programmable logic controller to achieve fully automatic and precise three-dimensional motion of the sand pouring mechanism. It is also equipped with a real-time monitoring system, and the various parts work together to achieve programmed automatic pouring of sand layer by layer and real-time data feedback.

[0017] The automatic sand pouring device includes a three-axis robotic arm 1, a sand pouring mechanism 2, a sand box 6, an electrical control system 4, a dust removal system, and a real-time monitoring system.

[0018] like Figure 4 and Figure 5 As shown, the three-axis robotic arm 1 is preferably a gantry-type three-axis robotic arm. Two X-axis travel rails 7 of the three-axis robotic arm 1 are fixedly installed on the ground, and two supporting columns 8 form sliding pairs with the two X-axis travel rails 7 respectively. A Y-axis 9 is fixed above the supporting columns 8, and the center of the Y-axis 9 is connected to the Z-axis 10. A sand-casting mechanism 2 is fixed at the lower end of the Z-axis 10. A Y-axis and Z-axis drive mechanism 12 is provided at the connection between the Y-axis 9 and the Z-axis 10. An X-axis drive mechanism 11 is provided at the bottom of the supporting columns 8. The X-axis drive mechanism 11 and the Y-axis drive mechanism are composed of a servo motor and a planetary reducer with a large reduction ratio. The Z-axis drive mechanism is composed of a servo motor and a worm gear reducer with a large reduction ratio. The Z-axis drive mechanism drives the Z-axis 10 to move up and down along the Z-axis 10 direction, the Y-axis drive mechanism drives the Z-axis 10 to slide along the Y-axis 9, and the X-axis drive mechanism 11 drives the supporting columns 8 to drag the Y-axis 9 to slide along the X-axis travel rails 7. The X-axis drive mechanism 11 and the Y-axis and Z-axis drive mechanisms 12 work together to drive the sand pouring mechanism 2 to move along the trajectory set in the program.

[0019] In this embodiment, mechanical limit switches and mechanical forced limiters are provided at the upper and lower ends of the Z-axis 10 to ensure operational safety. If the equipment malfunctions due to special reasons, the self-locking function of the worm gear reducer itself can prevent it from falling.

[0020] The sand pouring mechanism 2, from top to bottom, includes a sand storage tank 13, a rotary discharge valve 16, a sand storage tank connecting pipe 14, and an adapter nozzle 15. The sand storage tank 13 is bucket-shaped with a volume ≥500L. It is fixed to the lower end of the Z-axis 10 and used to load the sand to be poured. Sand is replenished via a fixed-point replenishment tank or a screw conveyor 3. The rotary discharge valve 16 is connected below the sand storage tank 13. The rotary discharge valve 16 has 8 sets of blades that evenly distribute the cavity into 8 sand storage chambers. During the pouring process, the blades rotate at a uniform speed, ensuring that the amount of sand stored in each sand storage chamber is consistent, thus guaranteeing a consistent pouring speed and providing power for the sand conveying process, preventing the sand from arching and clumping. A flat adapter nozzle 15 is connected below the rotary discharge valve 16 via the sand storage tank connecting pipe 14. This nozzle is used to pour sand into the sand box 6 placed on the ground. The opening of the adapter nozzle 15 is adjustable. Figure 8 As shown, an opening adjustment seat 21 and an opening adjustment plate 22 are provided at the nozzle opening of the nozzle box 20 of the adapter nozzle 15. The opening adjustment seat 21 has a groove inside, and the opening adjustment plate 22 slides in the groove of the opening adjustment seat 21 to change the opening of the adapter nozzle. The opening adjustment range of the adapter nozzle 15 is 0-20mm. The appropriate opening is selected according to the test and calibration results.

[0021] The testing and calibration process is as follows: Prepare a small calibration box, the width of which is smaller than the width of the adapter nozzle 15. In this embodiment, the size of the calibration box is selected as 300mm×300mm×100mm; Select different openings of the adapter nozzle 15 (1mm, 2mm, 3mm, 4mm, 5mm, 10mm, 20mm) and X-axis moving speeds of the three-axis robotic arm 1 (1mm / s, 2mm / s, 3mm / s, 4mm / s, 5mm / s, 10mm / s, 20mm / s, 30mm / s) in pairs, and perform sand pouring at different drop distances (100mm-1100mm, pouring once at 100mm intervals to obtain a point). Each time, the calibration box is filled. Calculate the relative density based on the weight and volume of the poured sand, and plot the relative density-drop distance curve for each combination.

[0022] In this embodiment, considering that due to the friction, adhesion or electrostatic effect between particles, the sand to be poured can easily form a stable arch structure above the outlet of the sand storage tank 13, blocking the channel and preventing the sand to be poured from continuing to flow out, multiple pneumatic vibrators 17 are provided in the sand storage tank 13. The pneumatic vibrators 17 act on the sand storage tank 13 to destroy the arch structure and restore the flow of the sand to be poured.

[0023] In this embodiment, the adapter nozzle 15 can be replaced with different width sizes.

[0024] To achieve fully automatic three-dimensional motion of the sand pouring mechanism 2, this invention introduces an electrical control system and a real-time monitoring system. The electrical control system employs a bus-based motion servo control system. Based on the sand pouring calibration results, sand particle size, and the opening of the matching nozzle 15, it designs the sand pouring path and the traveling speed of the sand pouring mechanism 2, and completes motion control through a PLC controller program. Preferably, specified parameters such as the size of the sand box 6 and the target compaction degree of the sand model can be input, and the electrical control system automatically plans the path accordingly.

[0025] The real-time monitoring system includes multiple weighing sensors 18 arranged on the upper part of the sand storage tank 13 and multiple radar level gauges 19 installed at the lower end of the rotary discharge valve 16, such as... Figure 6 and Figure 7 The weighing sensor 18 monitors the remaining sand mass in the sand storage tank 13 in real time and transmits the mass data to the electrical control system to determine whether to replenish the material at the replenishment station. The radar level gauge 19 is suitable for non-contact continuous measurement in powder and liquid scenarios. It has the advantages of strong anti-interference ability, high measurement accuracy, high reliability, and is not affected by harsh environments such as light, rain, snow, dust, and water mist. In this invention, it is used to monitor the height displacement of the sand in the sand box 6 in real time.

[0026] The electrical control system 4 calculates the mass of a single sand layer based on the change in the mass of the remaining sand. The volume of a single sand layer is obtained by combining the sand density. ; Calculate the depth of a single sand layer based on the height displacement of the sand material. The average porosity of a single-layer sand-cast layer was calculated from this. : ; in, Specific gravity of sand refers to the ratio of the mass of sand to the mass of an equal volume of pure water at 4°C, and is dimensionless. This is the density of water, expressed in kg / m³. 3 ; The dry density of each layer of sand, in kg / m³ 3 ; This represents the total mass of the poured sand material, expressed in kg. This refers to the total volume of the poured sand, expressed in cubic meters (m³). 3 ; This is the effective length of the sand box, in meters. This represents the effective width of the sandbox, in meters. Then, based on the average porosity The relative density D is obtained r : ; in, Maximum void ratio refers to the void ratio of sand in its loosest state; Minimum void ratio refers to the void ratio of sand in its most compact arrangement.

[0027] In this embodiment, the relative density of the prepared sand model is between 0.2 and 0.9, and the relative density error of each sand layer is ≤5%.

[0028] The electronic control system 4 automatically adjusts the sand pouring path, sand drop height, sand pouring mechanism 2 travel speed and the opening of the matching nozzle 15 according to the calculated relative density of the single-layer sand pouring layer, so as to obtain a sand model that meets the target relative density.

[0029] In this embodiment, the maximum sand pouring range of the automatic sand pouring device is ≥3m×2m, and the positioning accuracy is ≤±3mm.

[0030] A large amount of dust is generated during the sand pouring process, so a dust removal system is installed. This dust removal system is also controlled by the electrical control system 4, and includes a folding dust cover and a dust collector 5, such as... Figure 1 and Figure 3 As shown. The dust curtain of the folding dust cover is located on both sides of the crossbeam of the Y-axis 9 of the three-axis robotic arm 1, and can be expanded or retracted along the X-axis. When expanded, it covers the entire sand pouring path and the area of ​​the sand box 6. There are rotating shafts at the top of both ends of the folding dust cover, and dustproof cloths are installed on the rotating shafts. The dustproof cloths are raised and lowered by the rotating shafts. During operation, the dustproof cloths descend to the ground to block the spread of dust and work with the dust collector 5 to treat the dust. After the operation is completed, the dustproof cloths rise to the top.

[0031] The working principle of the automatic sand-pouring device for the ultragravity test sand model described in this invention is explained below: During the sand pouring operation, the three-axis robotic arm 1, under the control of the electronic control system 4, drives the sand pouring mechanism 2 to move layer by layer above the sand box 6 according to the pre-designed pouring trajectory. During the pouring process, the weighing sensor 18 monitors the remaining sand mass in the sand storage tank 13 in real time, and the radar level gauge 19 monitors the flatness of the sand pouring surface in the sand box 6 in real time. When the sand mass in the sand storage tank 13 reaches the set threshold, the electronic control system 4 records the position of the sand pouring mechanism 2 at this time, and controls the three-axis robotic arm 1 to drive the sand pouring mechanism 2 to the replenishment station to replenish sand by the screw feeder 3. After the sand replenishment is completed, it returns to the recorded position and continues to pour sand layer by layer according to the pre-designed trajectory until the pouring is completed.

[0032] The present invention also provides an automatic sand pouring method based on the aforementioned automatic sand pouring device for a high-gravity test sand model, comprising the following steps: S1. The electrical control system 4 controls the dust curtain of the folding dust cover to unfold along the X-axis to cover the entire preset sand pouring path and sand box 6. At the same time, it controls the dust cloth to descend to the ground through the rotating shaft and starts the dust collector 5 to handle the dust. S2. Determine the opening of the matching nozzle 15 and the travel speed of the sand pouring mechanism 2 according to the target relative density, and design the sand pouring path in combination with the sand particle size, and write the corresponding control program in the PLC controller. S3, PLC controller controls three-axis robotic arm 1 to drive sand pouring mechanism 2 to the replenishment station according to the designed sand pouring path. Sand is loaded through fixed-point replenishment bucket or screw feeder 3. After loading, sand pouring mechanism 2 moves to the sand pouring station and reaches the preset sand drop height. S4. The blades of the rotary discharge valve 16 begin to rotate, causing the sand to be poured in the sand storage tank 13 to be uniformly transported to the matching nozzle 15 and flow out from the nozzle of the matching nozzle 15 into the sand box 6. At the same time, the PLC controller controls the three-axis robotic arm 1 to drive the sand pouring mechanism 2 to pour layer by layer according to the designed sand pouring path. During the pouring process, the weighing sensor 18 and the radar level gauge 19 monitor the mass of the remaining sand in the sand storage tank 13 and the height displacement of the sand in the sand box 6, respectively, and transmit the data to the electrical control system 4. The electrical control system 4 calculates the relative density of the single-layer sand pouring and automatically adjusts the sand pouring path, the sand drop height, the travel speed of the sand pouring mechanism 2 and the opening of the matching nozzle 15 according to the relative density to obtain a sand model that meets the target relative density. S5. When the remaining sand in the sand storage bucket 13 reaches the preset threshold, the electrical control system 4 records the position of the sand pouring mechanism 2 at this time, and controls the three-axis robotic arm 1 to drive the sand pouring mechanism 2 to the replenishment station to replenish sand through the fixed-point replenishment bucket or the screw feeder 3. After the sand replenishment is completed, it returns to the recorded position and continues to pour sand layer by layer according to the predetermined design trajectory until the pouring is completed. S6, the electrical control system 4 controls the dust curtain of the folding dust cover to retract along the X-axis direction, and at the same time controls the dust cloth to rise to the top through the rotating shaft, and shuts off the dust collector 5.

[0033] To ensure operational safety, this invention is equipped with safety auxiliary facilities, including photoelectric limiters, mechanical limiters, anti-collision sensors, anti-fall auxiliary facilities, and anti-tipping auxiliary facilities. In addition, a safety-measured work area is set up, which will trigger a shutdown or corresponding protective measures if personnel are detected entering the work area.

[0034] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An automatic sand-pouring device for a sand model used in a high-gravity test, characterized in that, Includes a three-axis robotic arm, a sand pouring mechanism, a sand box, an electrical control system, and a real-time monitoring system; The three-axis robotic arm and the sand box are both fixed to the ground. The sand pouring mechanism is fixed to the lower end of the three-axis robotic arm. The three-axis robotic arm drives the sand pouring mechanism to perform layer-by-layer sand pouring operations above the sand box according to the preset sand pouring path. The sand pouring mechanism includes a sand storage tank, a rotary feeding valve, and an adapter nozzle connected sequentially from top to bottom. The sand storage tank is loaded with sand to be poured. The rotary feeding valve has multiple sets of blades inside, which divide the valve cavity into multiple sand storage chambers. During the pouring process, the blades rotate at a constant speed, ensuring that the amount of sand stored in each sand storage chamber is consistent, thereby guaranteeing a consistent pouring speed. The opening of the adapter nozzle can be adjusted to control the sand flow rate and drop point. The electrical control system adopts a bus motion servo control system, which designs the sand pouring path and the traveling speed of the sand pouring mechanism, and completes motion control through a PLC controller program; The real-time monitoring system acquires the real-time weight of the remaining sand in the sand storage tank and the real-time height displacement of the sand in the sand box, and transmits the data to the electrical control system. The electrical control system calculates the relative density of the single-layer sand pouring based on the real-time weight of the remaining sand in the sand storage tank and the real-time height displacement of the sand in the sand box, and automatically adjusts the sand pouring path, sand drop height, sand pouring mechanism travel speed and the opening of the matching nozzle according to the relative density of the single-layer sand pouring, so as to obtain a sand model that meets the target relative density.

2. The apparatus according to claim 1, characterized in that, The three-axis robotic arm includes two X-axis travel rails, two support columns, a Y-axis, a Z-axis, an X-axis drive system, and a Y-axis and Z-axis drive system. The two X-axis travel rails are fixedly installed on the ground. The two support columns form sliding pairs with the two X-axis travel rails respectively. A Y-axis is fixed on the top of the support columns, and the center of the Y-axis is connected to the Z-axis. A sand-casting mechanism is fixed at the lower end of the Z-axis. A Y-axis and Z-axis drive mechanism is provided at the connection between the Y-axis and the Z-axis. An X-axis drive mechanism is provided at the bottom of the support columns. The X-axis drive mechanism and the Y-axis drive system are composed of a servo motor and a planetary reducer with a large reduction ratio. The Z-axis drive mechanism is composed of a servo motor and a worm gear reducer with a large reduction ratio.

3. The apparatus according to claim 2, characterized in that, The sand pouring mechanism is fixed at the lower end of the Z-axis of the three-axis robotic arm.

4. The apparatus according to claim 1, characterized in that, The sand storage tank is bucket-shaped and has a volume of ≥500L.

5. The apparatus according to claim 1, characterized in that, The sand storage tank is equipped with multiple pneumatic vibrators, which act on the sand storage tank to break the arched structure that appears during the material feeding process and maintain the flow of sand.

6. The apparatus according to claim 1, characterized in that, The adapter nozzle includes a nozzle housing, an opening adjustment seat, and an opening adjustment plate. The opening adjustment seat is located at the nozzle opening at the lower end of the nozzle housing. The opening adjustment seat has a groove inside. The opening adjustment plate slides in the groove of the opening adjustment seat to change the opening of the adapter nozzle. The opening adjustment range of the adapter nozzle is 0-20mm.

7. The apparatus according to claim 1, characterized in that, The real-time monitoring system includes multiple weighing sensors arranged on the upper part of the sand storage tank and multiple radar level gauges installed at the lower end of the rotary discharge valve. The weighing sensors monitor the weight of the remaining sand in the sand storage tank in real time, and the radar level gauges monitor the height displacement of the sand in the sand box in real time.

8. The apparatus according to claim 2, characterized in that, It also includes a dust removal system, which consists of a foldable dust cover and a dust collector. The dust curtain of the foldable dust cover is placed on both sides of the three-axis robotic arm and can be unfolded or retracted along the X-axis of the three-axis robotic arm. When unfolded, it covers the entire sand pouring path and the sand box area. There are rotating shafts at the top of both ends of the foldable dust cover, and dustproof cloths are installed on the rotating shafts. The dustproof cloths are raised and lowered through the rotating shafts. During operation, the dustproof cloths are lowered to the ground to block the spread of dust, while the dust collectors handle the dust. After the operation is completed, the dustproof cloths are raised to the top.

9. The apparatus according to claim 1, characterized in that, The specific method for calculating the relative density of the single-layer sand pouring is as follows: calculate the mass of the single-layer sand pouring based on the change in weight of the remaining sand in the sand storage bucket during layer-by-layer pouring. The volume of a single sand layer is obtained by combining the sand density. The depth of a single sand layer is calculated based on the displacement of the sand material in the sand box during layer-by-layer pouring. The average porosity of a single-layer sand-cast layer was calculated from this. : ； in, Specific gravity of sand refers to the ratio of the mass of sand to the mass of an equal volume of pure water at 4°C, and is dimensionless. This is the density of water, expressed in kg / m³. 3 ; The dry density of each layer of sand, in kg / m³ 3 ; This represents the total mass of the poured sand material, expressed in kg. This refers to the total volume of the poured sand, expressed in cubic meters (m³). 3 ; This is the effective length of the sand box, in meters. This represents the effective width of the sandbox, in meters. Then, based on the average porosity The relative density D is obtained r : ； in, Maximum void ratio refers to the void ratio of sand in its loosest state; Minimum void ratio refers to the void ratio of sand in its most compact arrangement.

10. An automatic sand-pouring method based on the automatic sand-pouring device for a high-gravity test sand model according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Determine the opening of the appropriate nozzle and the travel speed of the sand pouring mechanism based on the target relative density, and design the sand pouring path in combination with the sand particle size, and write the corresponding control program into the electrical control system. S2. The electrical control system controls the three-axis robotic arm to drive the sand pouring mechanism to move along the designed sand pouring path to the material replenishment station to load sand. After loading is completed, the electrical control system controls the sand pouring mechanism to move to the sand pouring station and reach the preset sand drop height. S3. The blades of the rotary discharge valve begin to rotate, causing the sand to be poured in the sand storage tank to be uniformly transported to the matching nozzle and flow out from the nozzle opening into the sand box. At the same time, the electrical control system controls the three-axis robotic arm to drive the sand pouring mechanism to pour layer by layer according to the designed sand pouring path. During the pouring process, the real-time monitoring system obtains the real-time remaining sand mass in the sand storage tank and the real-time sand height displacement in the sand box, and transmits the data to the electrical control system. The electrical control system calculates the relative density of a single sand pouring layer based on this data, and automatically adjusts the sand pouring path, sand drop height, sand pouring mechanism travel speed and matching nozzle opening according to the relative density to obtain a sand model that meets the target relative density. S4. When the remaining sand in the sand storage tank reaches the preset threshold, the electrical control system records the location of the sand pouring mechanism at this time, and controls the three-axis robotic arm to drive the sand pouring mechanism to the replenishment station to replenish sand through the fixed-point replenishment tank or the screw feeder. After the replenishment is completed, it returns to the recorded position and continues to pour sand layer by layer according to the predetermined design trajectory until the pouring is completed.

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