Welding experiment system for simulating Antarctic inland environment and welding atmosphere control method thereof

Abstract

The invention discloses a welding experiment system for simulating the Antarctic inland environment and a welding atmosphere control method of the welding experiment system. The welding experiment system is provided with an experiment module, a fresh air system used for managing gas components in the module and controlling humidity, a low-temperature control system used for establishing and maintaining a low-temperature environment in the module through a low-temperature medium, a discharging system used for safely discharging the low-temperature medium, and a low-pressure control system used for establishing and maintaining a low-pressure environment in the module. And a monitoring system. The monitoring system carries out feedforward prediction and rolling optimization based on an MPC algorithm, a mathematical model of the experiment module and real-time environment parameters in the module, so that the temperature, the air pressure and the gas components in the module are kept constant. According to the invention, a welding experiment in a low-temperature and low-pressure environment in the South Pole inland can be simulated, the technical problem that multiple environmental parameters in a closed cabin are difficult to keep constant in a dynamic welding process is solved, and a high-reliability platform is provided for polar region welding process research.

Description

Technical Field

[0001] This invention relates to welding experimental systems, specifically to a welding experimental system simulating the Antarctic inland environment and a method for controlling the welding atmosphere thereon. Background Technology

[0002] Ambient temperature and air pressure have a significant impact on welding equipment, welding processes, and weld formation. Currently, welding experiments are generally conducted on-site, such as welding experiments in high-altitude environments. However, some specific environments, such as the Antarctic interior, do not meet the conditions for on-site testing. Therefore, it is necessary to design a welding experimental system that simulates the Antarctic interior environment. To simulate the low temperature and low air pressure characteristics of the Antarctic interior, this welding experimental system must be equipped with a sealed chamber. However, during the welding process, a large amount of heat, fumes, and shielding gases are continuously introduced into the sealed chamber, severely disturbing the temperature field, air pressure, and gas composition within the chamber. This leads to unstable environmental parameters, making it impossible to conduct welding experiments under constant conditions and seriously affecting the reliability of experimental data. Summary of the Invention

[0003] Purpose of the invention: The first purpose of this invention is to provide a welding experimental system that can simulate the low temperature and low pressure environment of the Antarctic interior; the second purpose of this invention is to provide a welding atmosphere control method for the welding experimental system, solving the technical problem of how to maintain constant temperature, air pressure and gas composition (oxygen content, dust) during dynamic welding.

[0004] Technical solution: The present invention provides a welding experiment system simulating the Antarctic inland environment, comprising an experimental chamber, a fresh air system, a cryogenic control system, a venting system, a low-pressure control system, and a monitoring system;

[0005] The experimental chamber includes a detachably connected chamber body and a top cover. The chamber body comprises an inner chamber and an insulated outer chamber. The inner chamber is equipped with a welding device and a dust removal and circulation device. Around the welding device are multiple sensor modules for collecting environmental parameters inside the chamber. The sensor modules include an oxygen content sensor, a temperature sensor, a pressure sensor, and a dust sensor. The dust removal and circulation device is used to automatically adjust based on the real-time concentration data detected by the dust sensor to maintain the stability of the gas composition inside the chamber.

[0006] The cryogenic control system is used to establish and maintain a cryogenic environment inside the cabin, including a cryogenic medium input pipeline, which is distributed in a ring around the outer wall of the inner cabin; one end of the cryogenic medium input pipeline is connected to a cryogenic medium tank, and a second pressure regulating valve is provided on the cryogenic medium input pipeline;

[0007] The venting system is used to safely vent cryogenic media, including an air-cooled evaporator, which is connected to the other end of the cryogenic media inlet pipeline via a cryogenic media outlet pipeline;

[0008] The low-pressure control system is used to establish and maintain a low-pressure environment inside the cabin, including a vacuum pump connected to the inner cabin via an air extraction line, which is equipped with a third pressure regulating valve and a vacuum valve.

[0009] The fresh air system is used for managing the gas composition and humidity control inside the chamber. It includes a fresh air exchanger, a water filtration system, and a first pressure regulating valve connected in sequence along the gas flow direction. The first pressure regulating valve is connected to the inner chamber through a gas input pipeline. The water filtration system is used to cool and dehumidify the air. An oxygen generator for supplementing pure oxygen to the experimental chamber is connected in parallel on the gas input pipeline.

[0010] The monitoring system predicts the trajectory of temperature, pressure, and gas composition changes within the chamber over a finite time domain based on sensor readings, the experimental chamber's mathematical model, and the MPC algorithm. It adjusts the flow rate of the cryogenic medium by controlling the second pressure regulating valve to precisely compensate for welding heat input; it regulates the intake rate by controlling the first pressure regulating valve and the timing of pure oxygen replenishment from the oxygen generator; and it matches the exhaust rate to the intake rate by controlling the third pressure regulating valve and the vacuum pump, thereby maintaining constant temperature, pressure, and gas composition within the chamber. The mathematical model is a dynamic coupling model of temperature, pressure, and gas composition within the experimental chamber.

[0011] Furthermore, the monitoring system includes a data acquisition module, a core controller, and a communication module. The data acquisition module is used to receive and process the detection values ​​of multiple sensor modules. The core controller deploys the mathematical model of the experimental chamber and the MPC algorithm, and combines the sensor detection values ​​to generate a set of coordinated control commands. The communication module outputs the control commands to the corresponding actuators.

[0012] Furthermore, the processing includes signal filtering, A / D conversion, physical quantity conversion, and data packaging, ultimately yielding accurate values ​​for cabin temperature, air pressure, oxygen content, and dust concentration.

[0013] Furthermore, the monitoring system also includes a human-machine interface to provide system status display, parameter settings, alarm information, and manual intervention access.

[0014] Furthermore, the water filtration system includes a compressor, a condenser, an expansion valve, and an evaporator connected in sequence. The compressor is connected to a fresh air exchanger, and the evaporator is connected to a first pressure regulating valve.

[0015] Furthermore, observation windows are installed on the cabin.

[0016] Furthermore, the welding device includes a motor, a welding torch, and a motion platform with a three-axis traveling mechanism. The motion platform is used to carry the workpiece and perform welding operations. The three-axis traveling mechanism is connected to the motor via a coupling. An electrical wire / fiber optic interface is provided on the top cover plate for connecting the welding torch inside the cabin to the welding machine outside the cabin.

[0017] The welding atmosphere control method of the welding experimental system of the present invention includes:

[0018] S1: System Modeling: Establish a mathematical model of the dynamic coupling of temperature, pressure, and gas composition in the experimental chamber;

[0019] S2: Data Acquisition: Real-time acquisition of measurement data from multiple sensor modules, including oxygen content, temperature, air pressure, and dust concentration;

[0020] S3: Prediction and Optimization: Within each control cycle, with the control objective of maintaining the setpoints of temperature, pressure, and gas composition, and with the operational limits of each actuator as constraints, the mathematical model is used to predict the trajectory of changes in cabin temperature, pressure, and gas composition within a finite time domain in the future, and a constrained multi-objective optimization problem is solved online to obtain a set of optimal control commands;

[0021] S4: Command execution: The control command is sent to the corresponding actuators of the cryogenic control system, the low-pressure control system and the fresh air system. By adjusting the flow rate of the cryogenic medium, the intake and exhaust rates and the start and stop of the oxygen generator, the thermal disturbance, mass disturbance and air pressure disturbance introduced by the welding process are counteracted in a coordinated manner to maintain the stability of the cabin environment parameters.

[0022] S5: Repeat steps S2 to S4 to achieve closed-loop rolling optimization.

[0023] Further, in step S1, the mathematical model is constructed based on the conservation of energy, the conservation of mass, and the ideal gas law, including:

[0024] A thermodynamic model, based on the law of conservation of energy, establishes a differential equation reflecting the temperature change inside the cabin:

[0025]

[0026] Where C is the equivalent heat capacity of the gas inside the cabin, T is the temperature inside the cabin, and Q is the temperature inside the cabin. weld The welding heat input power is given by hA, which is the product of the heat transfer coefficient h of the low-temperature medium input pipeline and the area A. T coolant The temperature of the low-temperature medium. and T air_in These are the fresh air intake mass flow rate and temperature, respectively. and These represent the mass flow rate and temperature of the supplemental oxygen, respectively. p and These are the specific heat capacities at constant pressure for air and oxygen, respectively.

[0027] The pressure dynamic model, based on the law of conservation of mass and the ideal gas law, establishes a differential equation reflecting the pressure changes inside the chamber:

[0028]

[0029] Where V is the net volume of the chamber, P is the absolute pressure inside the chamber, and R is the gas constant. This refers to the exhaust flow rate of the vacuum pump.

[0030] A gas composition model, based on the conservation of oxygen mass, establishes a differential equation reflecting the change in oxygen concentration inside the chamber:

[0031]

[0032] in, Let be the oxygen mass concentration, and D be the equivalent diffusion coefficient characterizing the gas mixing and diffusion effect within the cabin. This refers to the oxygen concentration in the fresh air.

[0033] Further, in step S3, the constraints include:

[0034] Operational constraints for each actuator: the opening degree of the first pressure regulating valve, the second pressure regulating valve, and the third pressure regulating valve is within their minimum and maximum opening degree range; the power of the vacuum pump is within its allowable operating range; and the start and stop of the oxygen generator conforms to the logic specifications.

[0035] Actuator change rate constraint: The change in the opening degree of each pressure regulating valve and the change in the power of the vacuum pump within adjacent control cycles shall not exceed the limit value;

[0036] System status safety constraints: Pressure and temperature fluctuations inside the chamber shall not exceed the safe operating range;

[0037] The objective function J of the optimization problem is:

[0038]

[0039] Where, N P To predict the time domain length, T(k), P(k), and Let T be the system state predicted by the model at the k-th future time. set P set and C set For the corresponding set value, ρ P and ρ C These are the weighting coefficients.

[0040] The principle of achieving heat-mass-pressure balance based on the MPC algorithm in this invention is as follows:

[0041] (1) Thermal balance: The huge heat generated by the welding arc will rapidly raise the local temperature. The MPC algorithm not only based on the current temperature feedback, but also on the future temperature rise trend predicted by the model, and in advance instructs to increase the liquid nitrogen flow rate. The heat is absorbed quickly and evenly through the pipes surrounding the outer wall of the inner chamber, maintaining a low temperature environment throughout. The heat is finally discharged through the venting system.

[0042] (2) Gas composition balance: The welding fumes are detected by the fume sensor and trigger the dust removal circulation device to start; at the same time, the protective gas and metal vapor will dilute the oxygen in the chamber. According to the prediction, the MPC algorithm will instruct the oxygen generator to start before the concentration drops to the threshold to supplement pure oxygen, while the water filtration system ensures that the supplemented gas is dry and water-free.

[0043] (3) Pressure balance: During welding, low-temperature cooling and gas injection / extraction will cause pressure changes. The MPC controller compares the reading of the pressure sensor with the set value and simultaneously considers the coupled effects of temperature and flow rate changes on pressure. It also coordinates and optimizes the opening combination of the first pressure regulating valve (controlling the intake volume) and the third pressure regulating valve (controlling the exhaust volume) to maintain the stability of the low-pressure environment in the chamber and avoid pressure fluctuations caused by controlling the intake or exhaust alone.

[0044] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0045] (1) This invention enables welding experiments in polar environments, providing support for the study of polar welding behavior, process windows, and equipment reliability, and filling a research gap in this field. At the same time, this invention can also be used to simulate welding experiments under various working conditions with different temperatures, low pressures, and gas compositions.

[0046] (2) This invention regards welding as a dynamic process that continuously introduces heat and mass disturbances. It uses the MPC algorithm to achieve coordinated control of multiple systems (fresh air, low temperature, low pressure), actively compensates for disturbances, realizes the "dynamic environmental balance" regulation of the welding process, and ensures the stability of environmental parameters.

[0047] (3) The fresh air system integrates three major functions: active dehumidification (water filtration system), on-demand oxygen generation and air pressure coordination. The water filtration system can effectively remove moisture from the air, fundamentally preventing the problems of frost and condensation in the low-temperature chamber; the oxygen generator can accurately replenish the oxygen consumed by welding; and the linkage between its air intake rate and the low-pressure control system solves the problem of air pressure runaway caused by continuous exhaust and replenishment, ensuring the stability of the low-pressure environment.

[0048] This invention provides a highly reliable platform for research on polar welding processes. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of a welding experiment system simulating the Antarctic inland environment provided in an embodiment of the present invention;

[0050] Figure 2 yes Figure 1 AA view;

[0051] Figure 3This is a schematic diagram of the structure of the cryogenic medium input pipeline surrounding the outer wall of the inner compartment in an embodiment of the present invention;

[0052] Figure 4 This is a control architecture diagram of the MPC (Multivariable Model Control Prediction) algorithm in an embodiment of the present invention;

[0053] Figure 5 This is a flowchart illustrating the usage method of the welding experiment system provided in this embodiment of the invention. Detailed Implementation

[0054] The invention will now be further described with reference to the accompanying drawings.

[0055] Appendix Figures 1 to 5 The accompanying figure labels are as follows:

[0056] 1. Experimental chamber; 1-1. Chamber body; 1-2. Top cover; 1-3. Welding machine; 1-4. Wire / fiber optic interface; 1-5. Left observation window; 1-6. Motor; 1-7. Coupling; 1-8. Front observation window; 1-9. Welding torch; 1-10. Motion platform; 1-11. Three-axis walking mechanism; 1-12. Dust removal and circulation device; 1-13. Right observation window; 1-14. Sensor module; 1-14-1. Oxygen content sensor; 1-14-2. Temperature sensor; 1-14-3. Air pressure sensor; 1-14-4. Fume sensor;

[0057] 2. Fresh air system; 2-1. Fresh air exchanger; 2-2. Water filtration system; 2-2-1. Compressor; 2-2-2. Condenser; 2-2-3. Expansion valve; 2-2-4. Evaporator; 2-3. First pressure regulating valve; 2-4. Gas input pipeline; 2-5. First shut-off valve; 2-6. Oxygen generator;

[0058] 3. Cryogenic control system; 3-1. Cryogenic medium tank; 3-2. Second pressure regulating valve; 3-3. Second shut-off valve; 3-4. First thermometer; 3-5. Cryogenic medium input pipeline;

[0059] 4. Venting system; 4-1. Low-temperature medium output pipeline; 4-2. Third shut-off valve; 4-3. Second thermometer; 4-4. Air-cooled evaporator;

[0060] 5. Low-pressure control system; 5-1. Air extraction pipeline; 5-2. Third pressure regulating valve; 5-3. Pressure gauge; 5-4. Vacuum valve; 5-5. Vacuum pump;

[0061] 6. Monitoring system; 6-1. Data acquisition module; 6-2. Core controller; 6-3. Communication module; 6-4. Human-machine interface.

[0062] Example 1

[0063] like Figure 1 and Figure 2 As shown, Example 1 provides a welding experiment system simulating the Antarctic inland environment, including an experimental chamber 1, a fresh air system 2, a cryogenic control system 3, a venting system 4, a low-pressure control system 5, and a monitoring system 6.

[0064] Experimental chamber 1 is used to simulate the polar environment and includes a detachably connected chamber 1-1 and a top cover 1-2. The chamber 1-1 includes an inner chamber and an insulated outer chamber.

[0065] The inner chamber houses a welding device and a dust removal and circulation device 1-12. The welding device includes a motor 1-6, a welding torch 1-9, a motion platform 1-10, and a three-axis travel mechanism 1-11. The motion platform 1-10 is used to carry the workpiece and perform welding operations. The three-axis travel mechanism 1-11 is connected to the motor 1-6 via a coupling 1-7, thus enabling the motor 1-6 to drive the motion platform 1-10 to move via the three-axis travel mechanism 1-11. Within the inner chamber, four sensor modules 1-14 are circumferentially distributed around the three-axis travel mechanism 1-11. These sensor modules include an oxygen content sensor 1-14-1, a temperature sensor 1-14-2, an air pressure sensor 1-14-3, and a fume sensor 1-14-4. The dust removal and circulation device 1-12 includes a fume hood, a fan, and a filter unit, used to promptly capture and purify the fume particles generated during the welding process. The operation status of the dust removal and circulation device 1-12 is automatically adjusted by the monitoring system 6 based on the real-time concentration data detected by the dust sensor 1-14-4, in order to maintain the stability of the gas composition inside the chamber.

[0066] The cabin 1-1 is equipped with a left observation window 1-5, a front observation window 1-8, and a right observation window 1-13. The top cover plate 1-2 is equipped with a wire / fiber optic interface 1-4 for connecting the welding torch 1-9 inside the cabin 1-1 and the welding machine 1-3 outside the cabin 1-1.

[0067] The fresh air system 2 is used for managing the gas composition and humidity control inside the chamber. It includes a fresh air exchanger 2-1, a water filtration system 2-2, and a first pressure regulating valve 2-3 connected sequentially along the gas flow direction. The first pressure regulating valve 2-3 is connected to the inner chamber via a gas input pipe 2-4. The water filtration system 2-2 is used for cooling and dehumidifying the air. It includes a compressor 2-2-1, a condenser 2-2-2, an expansion valve 2-2-3, and an evaporator 2-2-4 connected sequentially. The compressor 2-2-1 is connected to the fresh air exchanger 2-1, and the evaporator 2-2-4 is connected to the first pressure regulating valve 2-3. An oxygen generator 2-6 is connected in parallel to the gas input pipe 2-4 to supplement pure oxygen to the experimental chamber 1. A first shut-off valve 2-5 is installed on the outlet pipe of the oxygen generator 2-6.

[0068] The cryogenic control system 3 is used to establish and maintain the cryogenic environment inside the chamber. It includes a cryogenic medium inlet pipe 3-5, on which a cryogenic medium tank 3-1, a second pressure regulating valve 3-2, a second shut-off valve 3-3, and a first thermometer 3-4 are sequentially arranged along the fluid flow direction. The cryogenic medium inlet pipe 3-5 is distributed in a surrounding manner on the outer wall of the inner chamber to achieve uniform heat exchange. Figure 3 As shown in the figure. In this embodiment, liquid nitrogen is used as the cryogenic medium.

[0069] The venting system 4 is used to safely vent cryogenic media, including a cryogenic media output pipeline 4-1 connected to the other end of the cryogenic media input pipeline 3-5. A third shut-off valve 4-2, a second thermometer 4-3, and an air-cooled evaporator 4-4 are sequentially arranged on the cryogenic media output pipeline 4-1 along the fluid flow direction.

[0070] The low-pressure control system 5 is used to establish and maintain a low-pressure environment inside the cabin. It includes an air extraction pipeline 5-1 connected to the inner cabin. Along the air flow direction, the air extraction pipeline 5-1 is equipped with a third pressure regulating valve 5-2, a pressure gauge 5-3, a vacuum valve 5-4, and a vacuum pump 5-5.

[0071] The monitoring system 6 is the central hub of the dynamic environmental balance control mechanism, including a data acquisition module 6-1, a core controller 6-2, a communication module 6-3, and a human-machine interface 6-4. The data acquisition module 6-1 is used to receive and process detection signals from four sets of sensor modules 1-14 in real time. The processing includes signal filtering, A / D conversion, physical quantity conversion (such as converting voltage values ​​to temperature and pressure values), and data packaging, ultimately obtaining accurate values ​​of cabin temperature, air pressure, oxygen content, and dust concentration.

[0072] The core controller 6-2 employs a high-performance industrial computer or a programmable automation controller (PAC). The core controller 6-2 deploys the mathematical model and MPC algorithm for experimental chamber 1. The mathematical model is a dynamic coupling model of temperature, pressure, and gas composition in experimental chamber 1. Based on sensor readings, the mathematical model, and the MPC algorithm, the core controller 6-2 performs optimization calculations and outputs coordinated control commands.

[0073] The communication module 6-3 uses the fieldbus protocol to exchange data at high speed and reliably with the subsystem controllers of the fresh air system 2, the low temperature control system 3 and the low pressure control system 5, thereby enabling the output of control commands to the actuators of the fresh air system 2, the low temperature control system 3 and the low pressure control system 5.

[0074] The human-machine interface 6-4 is used to provide system status display, parameter settings, alarm information and manual intervention access; the manual intervention includes: forcibly starting or stopping a subsystem under special circumstances (such as emergency stop of the vacuum pump), temporarily modifying environmental parameter settings (such as fine-tuning the target temperature) or switching the system control mode (such as switching from automatic mode to manual mode).

[0075] The coordinated control instructions output by the core controller 6-2 achieve the following functions:

[0076] The flow rate of liquid nitrogen is adjusted by controlling the second pressure regulating valve 3-2 to precisely compensate for the welding heat input; the intake rate is adjusted by controlling the first pressure regulating valve 2-3, and the timing of pure oxygen replenishment from the oxygen generator 2-6 is controlled; the exhaust rate is matched with the intake rate by controlling the third pressure regulating valve 5-2 and the vacuum pump 5-5 (i.e., the intake and exhaust rates are linked for control), thereby maintaining constant temperature, pressure, and gas composition within the chamber. It should be noted that these control commands are not calculated independently, but rather the global optimal solution obtained simultaneously by the MPC algorithm during optimization, thus ensuring rapid, coordinated, and precise compensation for multiple disturbances in heat, mass, and pressure generated during the welding process, achieving dynamic balance of environmental parameters.

[0077] Example 2

[0078] Combination Figure 4 Example 2 provides a method for controlling the welding atmosphere of the welding experimental system described in Example 1, comprising the following steps:

[0079] S1: System Modeling: Establish a dynamic coupling mathematical model of temperature, pressure, and gas composition in Experiment Chamber 1. This mathematical model is based on energy conservation, mass conservation, and the ideal gas law. The specific construction process includes the following steps:

[0080] Model structure design: The experimental chamber 1 is regarded as a dynamic system with multiple inputs and multiple outputs. Its inputs include welding heat input power, cryogenic medium flow rate, fresh air system intake flow rate, oxygen generator output flow rate and vacuum pump exhaust flow rate. Its outputs are the average temperature, absolute pressure and oxygen concentration inside the chamber.

[0081] The mathematical model mainly consists of the following system of differential-algebraic equations:

[0082] ① Thermodynamic model: Based on the law of conservation of energy, establish a differential equation reflecting the temperature change inside the cabin:

[0083]

[0084] Where C is the equivalent heat capacity of the gas inside the cabin, T is the temperature inside the cabin, and Q is the temperature inside the cabin. weld The welding heat input power is given by hA, which is the product of the heat transfer coefficient h of the low-temperature medium input pipeline and the area A. Tcoolant The temperature of the low-temperature medium. and T air_in These are the fresh air intake mass flow rate and temperature, respectively. and These represent the mass flow rate and temperature of the supplemental oxygen, respectively. p and These are the specific heat capacities at constant pressure for air and oxygen, respectively.

[0085] ② Dynamic pressure model: Based on the law of conservation of mass and the ideal gas law, a differential equation reflecting the pressure change inside the chamber is established:

[0086]

[0087] Where V is the net volume of the chamber, P is the absolute pressure inside the chamber, and R is the gas constant. The vacuum pump exhaust flow rate is given. This equation simultaneously considers the coupled effects of net mass flow and temperature changes (thermal expansion and contraction) on pressure.

[0088] ③ Gas composition model: Based on the conservation of oxygen mass, a differential equation reflecting the change in oxygen concentration inside the chamber is established:

[0089]

[0090] in, Let be the oxygen mass concentration, and D be the equivalent diffusion coefficient characterizing the gas mixing and diffusion effect within the cabin. This refers to the oxygen concentration in the fresh air.

[0091] Parameter Identification and Model Validation: Dynamic response data of experimental chamber 1 under different inputs were collected through experimental methods such as step response testing and sinusoidal frequency sweep testing. Key unknown parameters in the mathematical model (such as equivalent heat capacity C, heat transfer coefficient h, and equivalent diffusion coefficient D) were determined using system identification algorithms (such as the least squares method). The simulation results of the identified model were compared with the measured data to verify the prediction accuracy of the model, and finally, it was embedded into the core controller 6-2 of the monitoring system 6.

[0092] S2: Data Acquisition: Real-time acquisition of measurement data from multiple sensor modules 1-14 located in key positions within the cabin, including temperature, air pressure, oxygen content, and dust concentration;

[0093] S3: Prediction and Optimization: Within each control cycle, with the setpoints of temperature, pressure and gas composition as the control objective and the physical operating limits of each actuator as the constraint, the trajectory of changes in cabin temperature, pressure and gas composition within a finite time domain is predicted based on the mathematical model, and a constrained multi-objective optimization problem is solved online to obtain a set of optimal control commands.

[0094] The constraints include:

[0095] Operational constraints for each actuator: the opening degree of the first pressure regulating valve 2-3, the second pressure regulating valve 3-2, and the third pressure regulating valve 5-2 are within their minimum and maximum opening degree ranges; the power of the vacuum pump 5-5 is within its allowable operating range; and the start and stop of the oxygen generator 2-6 conform to the logic specifications.

[0096] Actuator change rate constraint: To ensure equipment safety and control system stability, the change in the opening degree of each pressure regulating valve and the change in the power of the vacuum pump shall not exceed the limit value within adjacent control cycles;

[0097] System status safety constraints: Pressure and temperature fluctuations inside the chamber shall not exceed the safe operating range;

[0098] The objective function of the optimization problem is to minimize the weighted sum of squared deviations between the predicted system state values ​​and the set values ​​in the future time domain. The objective function J of the optimization problem is:

[0099]

[0100] Where, N P To predict the time domain length, T(k), P(k), and Let T be the system state predicted by the model at the k-th future time. set P set and C set For the corresponding set value, ρ P and ρ C The weighting coefficient is used to adjust the relative importance of different control objectives in the optimization. Its value is pre-tuned according to the control accuracy requirements during system initialization.

[0101] S4: Command Execution: The control commands are sent to the corresponding actuators of the cryogenic control system 3, the low-pressure control system 5, and the fresh air system 2. By adjusting the flow rate of the cryogenic medium, the intake and exhaust rates, and the start and stop of the oxygen generator, the thermal disturbances (such as electric arc heating), mass disturbances (such as oxygen consumption and smoke generation) and air pressure disturbances (such as air pressure fluctuations caused by temperature changes and intake and exhaust imbalances) introduced by the welding process are counteracted, thereby maintaining the stability of the cabin environmental parameters.

[0102] S5: Repeat steps S2 to S4 to achieve closed-loop rolling optimization.

[0103] Combination Figure 5 The present invention also provides a method for using the welding experimental system described in Embodiment 1, comprising the following steps:

[0104] (1) Preparatory work and environmental pre-establishment

[0105] (1.1) Workpiece clamping and sealing: Open the experimental chamber door and clamp the workpiece to be welded or repaired on the motion platform 1-10. Secure the welding torch 1-9 properly, and lead its cable out through the wire / fiber interface 1-4 on the top cover plate 1-2 and connect it to the external welding machine 1-3. Ensure the sealing of all interfaces to prevent external humid air from entering.

[0106] (1.2) Gas drying and replacement: After closing the cabin door, start the fresh air system 2. Outside air is drawn in through the fresh air exchanger 2-1, and after being deeply dehumidified by the water filtration system 2-2, it is sent into the cabin to replace the original air and ensure that the initial environment inside the cabin is dry.

[0107] (1.3) Establishing a Low-Temperature Environment: Set the target pre-cooling temperature through the human-machine interface 6-4. Start the low-temperature control system 3 and the venting system 4. The low-temperature medium flows through the low-temperature medium input pipeline 3-5 surrounding the inner chamber at the set flow rate to uniformly cool the experimental chamber. The monitoring system 6 automatically controls the cooling process until the temperature inside the chamber reaches the set value.

[0108] (1.4) Low-pressure environment establishment: After the cabin temperature stabilizes, start the low-pressure control system 5. Set the target air pressure value through the human-machine interface 6-4, and start the vacuum pump 5-5 to accurately reduce the air pressure in the cabin and maintain it at the target value.

[0109] (2) Welding and dynamic balance maintenance

[0110] (2.1) Start welding: Start the welding program by welding machine 1-3, and the welding device will start to work according to the preset trajectory.

[0111] (2.2) Automatic Environmental Control: During the welding process, the monitoring system 6 continuously collects data from various sensors and automatically controls the coordinated operation of each subsystem: the cryogenic control system 3 adjusts the flow rate of the cryogenic medium to offset the welding heat input; the fresh air system 2 adjusts the air intake and controls the oxygen generators 2-6 to maintain the gas composition; the low-pressure control system 5 adjusts the exhaust to stabilize the chamber pressure; and the dust removal and circulation devices 1-12 automatically start and stop to purify the fumes. This process requires no manual intervention, and the system automatically maintains all environmental parameters stable.

[0112] (3) Welding operation completed and system safe shutdown

[0113] (3.1) Stable recovery of environmental parameters: After welding is completed, turn off welding machines 1-3. Start the environmental recovery program through monitoring system 6, and each subsystem slowly restores the temperature and pressure inside the chamber to normal according to the preset safety program. (e.g., first slowly rise to normal pressure, and then slowly rise back to room temperature) to avoid damage to the workpiece or system equipment due to sudden changes in temperature and pressure.

[0114] (3.2) System Shutdown and Workpiece Removal: After the chamber environment returns to a safe state, shut down the low-pressure control system 5, the cryogenic control system 3, and the fresh air system 2 in sequence. Open the chamber door and remove the welded or repaired workpiece. System Power Off: After confirming that all equipment has stopped operating, disconnect the main power supply to the system.

Claims

1. A welding experimental system simulating the Antarctic inland environment, characterized in that, It includes an experimental chamber (1), a fresh air system (2), a cryogenic control system (3), a venting system (4), a low-pressure control system (5), and a monitoring system (6); The experimental chamber (1) includes a detachably connected chamber body (1-1) and a top cover plate (1-2). The chamber body (1-1) includes an inner chamber and an insulated outer chamber. The inner chamber is equipped with a welding device and a dust removal and circulation device (1-12). Multiple sensor modules for collecting environmental parameters inside the chamber are arranged around the welding device. The sensor modules include an oxygen content sensor, a temperature sensor, a pressure sensor, and a dust sensor. The dust removal and circulation device (1-12) is used to automatically adjust according to the real-time concentration data detected by the dust sensor to maintain the stability of the gas composition inside the chamber. The cryogenic control system (3) is used to establish and maintain the cryogenic environment inside the cabin, including a cryogenic medium input pipeline (3-5), which is distributed around the outer wall of the inner cabin; one end of the cryogenic medium input pipeline (3-5) is connected to the cryogenic medium tank (3-1), and a second pressure regulating valve (3-2) is provided on the cryogenic medium input pipeline (3-5); The venting system (4) is used to safely vent cryogenic media, including an air-cooled evaporator (4-4), which is connected to the other end of the cryogenic media inlet pipeline (3-5) through a cryogenic media outlet pipeline (4-1); The low-pressure control system (5) is used to establish and maintain a low-pressure environment inside the cabin, including a vacuum pump (5-5), which is connected to the inner cabin through an air extraction line (5-1). The air extraction line (5-1) is equipped with a third pressure regulating valve (5-2) and a vacuum valve (5-4). The fresh air system (2) is used for managing the gas composition and humidity control inside the chamber. It includes a fresh air exchanger (2-1), a water filtration system (2-2), and a first pressure regulating valve (2-3) connected in sequence along the gas flow direction. The first pressure regulating valve (2-3) is connected to the inner chamber through a gas input pipeline (2-4). The water filtration system (2-2) is used to cool and dehumidify the air. An oxygen generator (2-6) for supplementing pure oxygen to the experimental chamber (1) is connected in parallel on the gas input pipeline (2-4). The monitoring system (6) predicts the trajectory of temperature, pressure and gas composition changes in the chamber within a limited time domain based on sensor detection values, the mathematical model of the experimental chamber (1) and the MPC algorithm. It adjusts the flow rate of the cryogenic medium by controlling the second pressure regulating valve (3-2) to accurately compensate for welding heat input. It adjusts the intake rate by controlling the first pressure regulating valve (2-3) and controls the timing of pure oxygen replenishment by the oxygen generator (2-6). It adjusts the exhaust rate to match the intake rate by controlling the third pressure regulating valve (5-2) and the vacuum pump (5-5), thereby maintaining constant temperature, pressure and gas composition in the chamber. The mathematical model is a dynamic coupling mathematical model of temperature, pressure and gas composition in the experimental chamber (1).

2. The welding experimental system simulating the Antarctic inland environment according to claim 1, characterized in that, The monitoring system (6) includes a data acquisition module (6-1), a core controller (6-2), and a communication module (6-3). The data acquisition module (6-1) is used to receive and process the detection values ​​of multiple sensor modules. The core controller (6-2) deploys the mathematical model of the experimental chamber (1) and the MPC algorithm, and generates a set of collaborative control commands in combination with the sensor detection values. The communication module (6-3) outputs the control commands to the corresponding actuators.

3. The welding experimental system simulating the Antarctic inland environment according to claim 2, characterized in that, The processing includes signal filtering, A / D conversion, physical quantity conversion, and data packaging, ultimately yielding accurate values ​​for cabin temperature, air pressure, oxygen content, and dust concentration.

4. The welding experimental system simulating the Antarctic inland environment according to claim 2, characterized in that, The monitoring system (6) also includes a human-machine interface (6-4) for providing system status display, parameter settings, alarm information and manual intervention access.

5. The welding experimental system simulating the Antarctic inland environment according to claim 1, characterized in that, The water filtration system (2-2) includes a compressor (2-2-1), a condenser (2-2-2), an expansion valve (2-2-3), and an evaporator (2-2-4) connected in sequence. The compressor (2-2-1) is connected to the fresh air exchanger (2-1), and the evaporator (2-2-4) is connected to the first pressure regulating valve (2-3).

6. The welding experimental system for simulating the Antarctic inland environment according to claim 1, characterized in that, An observation window is provided on the hull (1-1).

7. The welding experimental system for simulating the Antarctic inland environment according to claim 1, characterized in that, The welding device includes a motor (1-6), a welding torch (1-9), and a motion platform (1-10) with a three-axis walking mechanism (1-11). The motion platform (1-10) is used to carry the workpiece and perform welding operations. The three-axis walking mechanism (1-11) is connected to the motor (1-6) through a coupling (1-7). The top cover plate (1-2) is provided with an electrical wire / fiber optic interface (1-4) for connecting the welding torch (1-9) inside the cabin (1-1) and the welding machine (1-3) outside the cabin (1-1).

8. A method for controlling the welding atmosphere of a welding experimental system according to any one of claims 1 to 7, characterized in that, include: S1: System modeling: Establish a mathematical model of the dynamic coupling of temperature, pressure and gas composition in the experimental chamber (1); S2: Data Acquisition: Real-time acquisition of measurement data from multiple sensor modules, including oxygen content, temperature, air pressure, and dust concentration; S3: Prediction and Optimization: Within each control cycle, with the control objective of maintaining the setpoints of temperature, pressure, and gas composition, and with the operational limits of each actuator as constraints, the mathematical model is used to predict the trajectory of changes in cabin temperature, pressure, and gas composition within a finite time domain in the future, and a constrained multi-objective optimization problem is solved online to obtain a set of optimal control commands; S4: Command execution: The control command is sent to the corresponding actuators of the cryogenic control system (3), the low-pressure control system (5) and the fresh air system (2). By adjusting the flow rate of the cryogenic medium, the intake and exhaust rates and the start and stop of the oxygen generator, the thermal disturbance, mass disturbance and air pressure disturbance introduced by the welding process are counteracted in a coordinated manner to maintain the stability of the cabin environment parameters. S5: Repeat steps S2 to S4 to achieve closed-loop rolling optimization.

9. The welding atmosphere control method for the welding experimental system according to claim 8, characterized in that, In step S1, the mathematical model is constructed based on the conservation of energy, the conservation of mass, and the ideal gas law, including: A thermodynamic model, based on the law of conservation of energy, establishes a differential equation reflecting the temperature change inside the cabin: Where C is the equivalent heat capacity of the gas inside the cabin, T is the temperature inside the cabin, and Q is the temperature inside the cabin. weld The welding heat input power is given by hA, which is the product of the heat transfer coefficient h of the low-temperature medium input pipeline and the area A. T coolant The temperature of the low-temperature medium. and T air_in These are the fresh air intake mass flow rate and temperature, respectively. and These represent the mass flow rate and temperature of the supplemental oxygen, respectively. p and These are the specific heat capacities at constant pressure for air and oxygen, respectively. The pressure dynamic model, based on the law of conservation of mass and the ideal gas law, establishes a differential equation reflecting the pressure changes inside the chamber: Where V is the net volume of the chamber, P is the absolute pressure inside the chamber, and R is the gas constant. This refers to the exhaust flow rate of the vacuum pump. A gas composition model, based on the mass conservation of oxygen components, establishes a differential equation reflecting the change in oxygen concentration inside the chamber: in, Let be the oxygen mass concentration, and D be the equivalent diffusion coefficient characterizing the gas mixing and diffusion effect within the cabin. This refers to the oxygen concentration in the fresh air.

10. The welding atmosphere control method for the welding experimental system according to claim 8, characterized in that, In step S3, the constraints include: Operational constraints for each actuator: the opening degree of the first pressure regulating valve (2-3), the second pressure regulating valve (3-2), and the third pressure regulating valve (5-2) is within their minimum and maximum opening degree range; the power of the vacuum pump (5-5) is within its allowable operating range; and the start and stop of the oxygen generator (2-6) conforms to the logic specifications. Actuator change rate constraint: The change in the opening degree of each pressure regulating valve and the change in the power of the vacuum pump within adjacent control cycles shall not exceed the limit value; System status safety constraints: Pressure and temperature fluctuations inside the chamber shall not exceed the safe operating range; The objective function J of the optimization problem is: in, NP To predict the time domain length, T(k), P(k), and Let T be the system state predicted by the model at the k-th future time. set P set and C set For the corresponding set value, ρ P and ρ C These are the weighting coefficients.

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