Freeze-thaw cycle testing machine for sand erosion

Abstract

The invention belongs to the technical field of material performance testing equipment, and particularly relates to a sand wind erosion freezing and thawing cycle testing machine which comprises a support, a test box is arranged at the top of the support, and the test box is of a closed box body structure; a sample fixing device is arranged at the inner bottom of the test box, and is adaptive to samples with different sizes by adjusting the position of a fixing sheet and the tightness of a screw; a sand erosion mechanism is arranged in the test box, controllable airflow is generated through an aerostatic press, and gas-solid two-phase flow carrying sand grains is formed in a sand conveying pipeline; sand flow with set wind speed and sand flow is sprayed to a test sample by means of a spray head, so that a real sand erosion environment is simulated; a freezing and thawing circulating mechanism is arranged in the sample fixing device. According to the device and the method, wide-temperature-range freeze-thaw cycle and adjustable-nozzle angle / distance, sand discharge and wind speed wind-sand erosion synchronous simulation can be realized, the authenticity and reliability of test data are further improved, the test process is simplified, and the test efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of material performance testing equipment, specifically relating to a wind and sand erosion freeze-thaw cycle testing machine. Background Technology

[0002] In cold, arid, and windy regions, such as the desert areas of Northwest my country, building structures, road surfaces, and slope soil and rock are subjected to the dual effects of freeze-thaw cycles and wind erosion over a long period of time. Freeze-thaw cycles cause the freezing expansion and thawing contraction of pore water inside the material, damaging the material's microstructure; wind erosion, on the other hand, impacts and abrades the material surface, accelerating damage and aging.

[0003] Currently, most existing testing equipment suffers from two key shortcomings: first, its temperature control range is narrow, failing to cover the extreme temperature range of -30°C to 60°C, and the temperature cycling speed and cycle cannot be flexibly customized, making it unable to simulate freeze-thaw conditions under extreme climates; second, its ability to adjust wind and sand erosion parameters is weak, with fixed nozzle angles and distances, and uncontrollable sand output and wind speed, failing to recreate erosion environments under different wind and sand intensities, and lacking the ability to simultaneously simulate both environments. To obtain material performance data under the combined effects of these two factors, separate testing equipment is required, and sample transfer is susceptible to external interference, resulting in low accuracy and efficiency of experimental data, failing to meet the needs of scientific research and engineering fields for rapid performance evaluation of materials under complex and harsh environments. Therefore, developing a testing machine with adjustable freeze-thaw cycles over a wide temperature range, controllable multi-parameter wind and sand erosion, and the ability to simultaneously simulate both environments has become an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a wind and sand erosion freeze-thaw cycle test machine that can realize the synchronous simulation of wind and sand erosion with a wide temperature range freeze-thaw cycle and adjustable nozzle angle / distance, sand output, and wind speed, thereby further improving the authenticity and reliability of test data, simplifying the test process, and improving test efficiency.

[0005] The specific technical solution adopted by this invention is as follows: A wind and sand erosion freeze-thaw cycle test machine includes a support frame, and a test chamber is provided on the top of the support frame. The test chamber is a sealed box structure. The bottom of the test chamber is equipped with a sample fixing device, which can be adjusted to accommodate samples of different sizes by adjusting the position of the fixing plate and the tightness of the screws; The test chamber is equipped with a wind and sand erosion mechanism. A controllable airflow is generated by an air compressor to form a gas-solid two-phase flow carrying sand particles in the wind and sand conveying pipeline. The wind and sand flow with a set wind speed and sand particle flow rate is sprayed onto the test sample by a nozzle to simulate the real wind and sand erosion environment. The sample fixing device is equipped with a freeze-thaw cycle mechanism. Through the alternating operation of the low-temperature cooling chamber and the high-temperature heating chamber, combined with the three-dimensional heat transfer of the circulation pipe, the temperature inside the test chamber can achieve temperature cycle changes within a wide temperature range to simulate freeze-thaw conditions under extreme climates.

[0006] The test chamber has a double insulation layer on the inside, with an aluminum foil reflective film sandwiched between the double insulation layers.

[0007] The sample fixing device includes a fixing base located at the bottom of the test chamber, and the top of the fixing base is provided with multiple fixing plates by screws.

[0008] The wind and sand erosion mechanism includes a conical discharge hopper located at the top of the test chamber. The discharge end of the conical discharge hopper extending into the test chamber is equipped with an adjustment mechanism. An air compressor is located at the top of the test chamber, and the output end of the air compressor is connected to a Venturi tube via a pipe.

[0009] The test chamber is equipped with a robotic arm on its inner side, and the output end of the robotic arm is equipped with a nozzle. The nozzle is connected to the discharge end of the venturi tube through a pipe.

[0010] The regulating mechanism includes a throttling pipe that communicates with the bottom of the conical discharge hopper. The bottom of the throttling pipe is connected to the negative pressure port of the Venturi tube through a pipe. A drive shaft is rotatably installed inside the throttling pipe, and a baffle is fixed to the outer wall of the drive shaft. The drive shaft extends to one end outside the throttle tube and is fixed with a second gear. A servo motor is provided on the outer wall of the throttle tube. The output shaft of the servo motor is fixed with a first gear that meshes with the second gear. The diameter of the first gear is smaller than the diameter of the second gear.

[0011] The freeze-thaw circulation mechanism includes an installation space disposed within a fixed base, a partition fixed to the inner side of the installation space, and multiple U-shaped circulation tubes arranged equidistantly above the partition. One end of each of the plurality of U-shaped circulation tubes extends below the partition and is connected to a first collecting mechanism; the other ends of the plurality of U-shaped circulation tubes extend below the partition and are connected to a second collecting tube. A storage box is fixed to one side of the bottom of the partition, and a return pipe connected to the second manifold is connected to one side of the storage box. A circulation pump is provided at the bottom of the partition on one side of the storage box, and the circulation pump is connected to the storage box through a medium pipe.

[0012] The bottom of the partition and on one side of the circulating pump are provided with a low-temperature refrigeration box and a high-temperature heating box. The inlets of the low-temperature refrigeration box and the high-temperature heating box are connected to the outlet of the circulating pump through a medium pipe. The low-temperature refrigeration box and the high-temperature heating box are both equipped with electromagnetic valves on the medium pipes connecting them to the circulating pump. The discharge ports of the low-temperature refrigeration box and the high-temperature heating box are connected to the first collecting mechanism through the medium pipes.

[0013] The test chamber has a mesh screen at its inner bottom and below the fixed base. The bottom of the test chamber has a sand collection hopper, and the bottom of the sand collection hopper is connected to a sand collection box. A removable sand collection box is provided on one side of the sand collection box.

[0014] The first gathering mechanism includes a gathering block, and the gathering block has three mixing chambers arranged in a stepped manner and connected to each other. The diameters of the mixing chambers from largest to smallest are the first mixing chamber, the second mixing chamber, and the third mixing chamber. A damped water wheel is installed on one side of the first mixing chamber. One end of the buffer water wheel is located in the second mixing chamber and is provided with a mixing spiral blade. The diameter and pitch of the mixing spiral blade decrease step by step in the direction away from the buffer water wheel. The inside of the collecting block is provided with a branch channel that communicates with the third mixing chamber. The branch channel is connected to one end of the U-shaped circulation pipe. A diversion block with a triangular cross-section is provided in the middle of the connection between the branch channel and the third mixing chamber. The diversion block and the branch channel are fixed with a 120° chamfer. The inside of the collecting block is provided with two confluence channels that connect to the first mixing chamber, and the first mixing chamber of the confluence channels is inclined. The other ends of the two confluence channels are connected to the low-temperature refrigeration box and the high-temperature heating box respectively through medium pipes.

[0015] The technical effects achieved by this invention are as follows: This invention enables real-time collaborative operation of a wind and sand erosion system and a freeze-thaw cycle system through a PLC controller, accurately reproducing the coupling effect of two extreme climates in the natural environment. It overcomes the limitations of traditional equipment that can simulate alone, and the test data can better reflect the actual service status of materials, significantly improving its reference value.

[0016] This invention achieves automatic and precise adjustment of sand output, jet wind speed, and nozzle angle / distance by using a closed-loop coordination of wind and sand erosion parameters through a servo motor, flow sensor, wind speed sensor, and air compressor. The freeze-thaw cycle relies on a PID+fuzzy control algorithm and multi-point temperature sensors to achieve custom control of temperature cycle speed and freeze-thaw cycle over a wide temperature range, meeting the refined testing needs of different materials.

[0017] This invention uses a sample fixing device to securely fix test samples of different sizes by adjusting the position of the fixing plate and the tightness of the screws, without the need to replace the special clamps; the double-layer vacuum tempered glass of the chamber door is filled with inert gas, which completely solves the problem of fogging and frost on the observation window; together with the capacitive screen control that can switch between Chinese and English, it makes monitoring the test process and setting parameters more convenient.

[0018] This invention significantly reduces energy loss in low-temperature environments through a combination design of a double-layer insulation layer and an aluminum foil reflective film on the inner side of the test chamber; the sand recovery mechanism facilitates sand recovery through a strainer, a 15° inclined sand collection hopper, and a pluggable sand collection box, avoiding resource waste and reducing test costs.

[0019] This invention utilizes a ceramic wear-resistant coating on the inner wall of the sand conveying pipeline to resist sand erosion and wear, while the outer centrifugal glass wool insulation layer prevents condensation from affecting the conveying process. The test chamber is made of 5mm thick 304 stainless steel, which is resistant to low temperatures and corrosion. Combined with the efficient heat transfer design of the U-shaped circulation pipe, it not only improves the testing efficiency but also extends the overall service life of the equipment.

[0020] This invention can meet the environmental adaptability testing of materials in multiple fields such as geotechnical engineering, building materials, road engineering, and rail transit. It covers a variety of test scenarios, including the individual and coupled effects of freeze-thaw cycles and wind and sand erosion. It has strong versatility and broad application prospects. Attached Figure Description

[0021] Figure 1 This is a front view structural diagram of the present invention; Figure 2 This is a side view of the structure of the present invention; Figure 3 This is a schematic diagram of the internal structure of the test chamber of the present invention; Figure 4 This is a schematic diagram of the adjustment mechanism structure of the present invention; Figure 5 This is a schematic diagram of the Venturi tube structure of the present invention; Figure 6 This is a schematic diagram of the cross-sectional structure of the test chamber material of the present invention; Figure 7 This is a bottom view schematic diagram of the freeze-thaw cycle mechanism of the present invention; Figure 8 This is a top view schematic diagram of the freeze-thaw cycle mechanism of the present invention.

[0022] Figure 9 This is a cross-sectional structural diagram of the first collection mechanism of the present invention; Figure 10 This is a schematic diagram of the nozzle structure of the present invention.

[0023] The attached diagram lists the components represented by each number as follows: 1. Support frame; 2. Test chamber; 3. Double-layer insulation layer; 4. Aluminum foil reflective film; 5. Robotic arm; 6. Nozzle; 61. Pipe body; 62. Diverter block; 63. Guide channel; 64. Dividing hole; 65. Airbag ring; 66. Air pump; 7. Conical discharge hopper; 8. Adjustment mechanism; 81. Throttling tube; 82. Baffle; 83. Servo motor; 84. First gear; 85. Second gear; 86. Limiting block; 87. Limiting groove; 9. Pneumatic compressor; 10. Venturi tube; 11. Fixing base; 12. Strainer; 13. Fixing plate; 14. 15. Partition plate; 16. U-shaped circulation pipe; 17. Storage tank; 18. Circulation pump; 19. Low temperature refrigeration box; 20. High temperature heating box; 20. First collection mechanism; 201. Collection block; 202. First mixing chamber; 203. Buffer water wheel; 204. Mixing spiral blade; 205. Second mixing chamber; 206. Third mixing chamber; 207. Diverter block; 208. Branch channel; 209. Convergence channel; 21. Second collection pipe; 22. Return pipe; 23. Sand collection hopper; 24. Sand collection box; 25. Sand collection container; 27. Display screen controller. Detailed Implementation

[0024] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0025] like Figure 1 Figure 2 , Figure 3 and Figure 6 As shown, a wind and sand erosion freeze-thaw cycle test chamber includes a support 1, with a test chamber 2 on top of the support 1. The test chamber 2 is a sealed chamber structure. The inner side of the test chamber 2 is provided with a double-layer insulation layer 3, and an aluminum foil reflective film 4 is sandwiched between the double-layer insulation layer 3, which has excellent overall insulation performance and effectively reduces energy consumption. The test chamber 2 is made of 304 stainless steel with a thickness of 5mm, which has good low temperature resistance and corrosion resistance. A door is hinged on one side of the test chamber 2, and the door is inlaid with double-layer vacuum tempered glass. Inert gas is filled between the double-layer vacuum tempered glass to effectively prevent fogging and frost on the observation window, making it easy for operators to clearly observe the changes in the surface state of the sample.

[0026] The test chamber 2 has a display screen controller 27 located on one side of the chamber door. The display screen controller 27 uses a PLC controller and integrates a 4.5-inch capacitive screen. The PLC controller enables real-time coordinated operation of the freeze-thaw cycle system and the wind and sand erosion system. The capacitive screen supports Chinese / English interface switching and can set freeze-thaw cycle parameters (freezing temperature, thawing temperature, temperature cycle rate, freeze-thaw cycle, total test time, number of cycles) and wind and sand erosion parameters (nozzle angle, nozzle distance, sand output, jetting wind speed, erosion time).

[0027] like Figure 2 As shown, the bottom of the test chamber 2 is equipped with a sample fixing device, which can be adapted to different sizes of samples by adjusting the position of the fixing piece 13 and the tightness of the screw; the sample fixing device includes a fixing base 11 set in the bottom of the test chamber 2, and multiple fixing pieces 13 are provided on the top of the fixing base 11 by screws.

[0028] like Figures 2-6 As shown, the test chamber 2 is equipped with a wind and sand erosion mechanism. A controllable airflow is generated by the air compressor 9 to form a gas-solid two-phase flow carrying sand particles in the wind and sand conveying pipeline. The wind and sand flow with a set wind speed and sand particle flow rate is sprayed onto the test sample by the nozzle 6 to simulate the real wind and sand erosion environment. The wind and sand erosion mechanism includes a conical discharge hopper 7 set at the top of the test chamber 2. The discharge end of the conical discharge hopper 7 extending into the test chamber 2 is equipped with an adjustment mechanism 8. An air compressor 9 is set at the top of the test chamber 2. The output end of the air compressor 9 is connected to a venturi tube 10 through a pipe. The inner side of the test chamber 2 is equipped with a robotic arm 5, and the output end of the robotic arm 5 is equipped with a nozzle 6. The nozzle 6 is connected to the discharge end of the venturi tube 10 through a pipe. A wind speed sensor is installed at the nozzle 6 to monitor the spray wind speed in real time. like Figure 10 As shown, the nozzle 6 includes a tube body 61, and a flow divider block 62 is threadedly connected to the nozzle of the tube body 61. A flow guide groove 63 is provided on the top of the flow divider block 62. The top diameter of the flow guide groove 63 is larger than the top and bottom diameters. Multiple equal-dividing holes 64 are arrayed on the bottom of the flow divider block 62. The diameter of the equal-dividing holes 64 is 3-4mm. A flow guide groove 63 communicating with the equal-dividing holes 64 is provided on the top of the flow divider block 62. The diameter of the flow guide groove 63 increases vertically away from the equal-dividing holes 64. The top sides of the multiple flow guide grooves 63 are connected to each other. An airbag ring 65 is provided on the inner side of the evenly distributed hole 64, and an air pump 66 is provided on the outer side of the tube body 61, and the air pump 66 is connected to the airbag ring 65.

[0029] Based on the above structure, the test requirements of "uniform coverage, precise control, and dynamic adaptation" of wind and sand flow are achieved; the pipe body 61 and the diverter block 62 adopt a threaded connection design, which is convenient for disassembly and assembly, and facilitates the maintenance, replacement and cleaning of the diverter block 62 and its internal structure in the later stage.

[0030] The guide grooves 63 at the top of the diversion block 62 have a structure that "gradually increases in size in the vertical direction away from the equalization holes 64," and multiple guide grooves 63 are interconnected on one side of their tops. This allows for efficient convergence and guidance of the wind and sand flow. Combined with the equalization holes 64 distributed in an array at the bottom, the wind and sand flow can be evenly distributed to each equalization hole 64, achieving uniform coverage of the wind and sand flow. The equalization holes 64 are set at 3-4mm. The reasonable diameter, combined with the gradient diameter design of the guide channel 63, further ensures the uniformity of the wind and sand flow output, while laying a structural foundation for precise flow control. The airbag ring 65 inside the equalization hole 61 is connected to the air pump 66 outside the pipe body 61. By adjusting the expansion and contraction of the airbag ring 65 through the air pump 66, the actual flow diameter of the equalization hole 64 can be dynamically changed, realizing precise control of the wind and sand flow output and meeting the requirements of precise and controllable testing. The cooperation between the airbag ring 65 and the air pump 66 forms a dynamic adjustment mechanism, which can adjust the flow state of the equalization hole 64 in real time according to the needs of different wind and sand flow intensities and coverage areas during the test, realizing dynamic adaptation to test conditions and improving the flexibility and applicability of the test.

[0031] The regulating mechanism 8 includes a throttling pipe 81 connected to the bottom of the conical discharge hopper 7. The bottom of the throttling pipe 81 is connected to the negative pressure port of the venturi tube 10 through a pipe. A drive shaft is rotatably installed inside the throttling pipe 81, and a baffle 82 is fixed on the outer wall of the drive shaft. A flow sensor is provided at the bottom of the throttling pipe 81 for real-time monitoring of sand flow. A second gear 85 is fixed at one end of the drive shaft extending to the outside of the throttle tube 81. A servo motor 83 is provided on the outer wall of the throttle tube 81. A first gear 84 meshing with the second gear 85 is fixed on the output shaft of the servo motor 83. The diameter of the first gear 84 is smaller than the diameter of the second gear 85. A limit groove 87 is provided on one side of the second gear 85. A limit block 86 that is slidably connected to the limit groove 87 is fixed on one side of the throttle tube 81 to limit the rotation of the baffle 82. The inner wall of the pipe is coated with a wear-resistant coating, and the outer layer of the pipe is wrapped with a heat insulation layer. The wear-resistant coating on the inner wall of the pipe is a ceramic coating with a thickness of 2-3mm, and the outer heat insulation layer is a centrifugal glass wool insulation layer with a thickness of 50mm, to prevent condensation inside the pipe from affecting the transport of sand in low-temperature environments.

[0032] According to the above structure, the servo motor 83 drives the first gear 84 to rotate, the first gear 84 drives the second gear 85 to rotate, the second gear 85 drives the transmission shaft to rotate, and the transmission shaft drives the baffle 82 to rotate, thereby controlling the opening and closing degree of the baffle 82. Combined with the feedback data from the flow sensor, the sand output is precisely controlled. The air compressor 9 is configured to change the wind speed by adjusting the output air pressure. The pressure adjustment range corresponds to the continuous adjustment of the wind speed, providing stable and controllable power for sand and dust transportation. The robotic arm 5 is configured to improve the flexibility of nozzle adjustment. Both the robotic arm 5 and the flow sensor are electrically connected to the display screen controller 27 to realize automatic and precise control of nozzle angle, distance and spray wind speed. When in use, start the air compressor 9 to generate air pressure. When the gas flows through the venturi tube 10, it sucks the sand from the conical discharge hopper 7 into the venturi tube 10 through the negative pressure port, and then enters the nozzle 6 through the pipe, and is sprayed onto the workpiece through the nozzle 6.

[0033] like Figures 7-8 As shown, the sample fixing device is equipped with a freeze-thaw cycle mechanism. Through the alternating operation of the low-temperature cooling chamber 18 and the high-temperature heating chamber 19, combined with the three-dimensional heat transfer of the U-shaped circulation pipe 15, the temperature inside the test chamber can achieve temperature cycle changes within a wide temperature range to simulate freeze-thaw conditions under extreme climates. The freeze-thaw circulation mechanism includes an installation space set in the fixed base 11, a partition 14 fixed on the inner side of the installation space, and multiple U-shaped circulation pipes 15 arranged equidistantly above the partition 14; the arrangement of multiple U-shaped circulation pipes 15 reduces the medium flow distance and improves the efficiency and effect of heating or freeze-thawing the workpiece. One end of a plurality of U-shaped circulation tubes 15 extends to the bottom of a partition 14 and is connected to a first collecting mechanism 20; the other ends of the plurality of U-shaped circulation tubes 15 extend to the bottom of a partition 14 and are connected to a second collecting tube 21. A storage tank 16 is fixed to one side of the bottom of the partition 14. A return pipe 22 connected to the second manifold 21 is connected to one side of the storage tank 16. A circulation pump 17 is provided at the bottom of the partition 14 on one side of the storage tank 16, and the circulation pump 17 is connected to the storage tank 16 through a medium pipe. At the bottom of the partition 14 and on one side of the circulating pump 17, there is a low-temperature refrigeration box 18 and a high-temperature heating box 19. The inlets of the low-temperature refrigeration box 18 and the high-temperature heating box 19 are connected to the outlet of the circulating pump 17 through a medium pipe. Electromagnetic valves are provided on the medium pipes connecting the low-temperature refrigeration box 18 and the high-temperature heating box 19 to the circulating pump 17. The discharge ports of the low-temperature refrigeration box 18 and the high-temperature heating box 19 are connected to the first collection mechanism 20 through the medium pipes. One-way valves are provided on the medium pipes connecting the low-temperature refrigeration box 18 and the high-temperature heating box 19 to the first collection mechanism 20. According to the above structure, the low-temperature refrigeration box 18 adopts multi-stage compression refrigeration technology, with a minimum refrigeration temperature of -35℃, and the high-temperature heating box 19 adopts stainless steel heating tubes, with a maximum heating temperature of 70℃. When heating the workpiece on the fixed seat 11, the solenoid valve connecting the low-temperature refrigeration box 18 and the circulating pump 17 is closed, and the solenoid valve connecting the high-temperature heating box 19 and the circulating pump 17 is opened, starting the circulating pump 17. The circulating pump 17 transports the medium in the storage box 16 into the high-temperature heating box 19. After being heated by the high-temperature heating box 19, the medium enters the first collection mechanism 20, and then enters multiple U-shaped circulation pipes 15. The U-shaped circulation pipe 15 heats the workpiece on the fixed seat 11; when cooling the workpiece, the solenoid valve connecting the high-temperature heating box 19 and the circulation pump 17 is closed, and the solenoid valve connecting the low-temperature cooling box 18 and the circulation pump 17 is opened, and the circulation pump 17 is started. The circulation pump 17 transports the medium in the storage box 16 into the high-temperature heating box 19. After being heated by the high-temperature heating box 19, the medium enters the first collection mechanism 20, and then enters multiple U-shaped circulation pipes 15 through the first collection mechanism 20. The U-shaped circulation pipes 15 cool the workpiece on the fixed seat 11. The high-temperature medium and the low-temperature medium coming out of the high-temperature heating box 19 and the low-temperature cooling box 18 pass through.

[0034] like Figure 9 As shown, the first gathering mechanism 20 includes a gathering block 201. The gathering block 201 has three mixing chambers arranged in a stepped manner and connected to each other. The diameters of the mixing chambers from largest to smallest are the first mixing chamber 202, the second mixing chamber 205 and the third mixing chamber 206. A damped water wheel 203 is installed on one side of the first mixing chamber 202. One end of the buffer water wheel 203 is located in the second mixing chamber 205 and is provided with a mixing spiral blade 204. The diameter and pitch of the mixing spiral blade 204 decrease step by step in the direction away from the buffer water wheel 203. The inside of the collecting block 201 is provided with a branch channel 208 that communicates with the third mixing chamber 206. The branch channel 208 is connected to one end of the U-shaped circulation pipe 15. The middle part of the connection between the branch channel 208 and the third mixing chamber 206 is provided with a diverting block 207 with a triangular cross section. The diverting block 207 and the branch channel 208 are fixed with a 120° chamfer. The inside of the collecting block 201 is provided with two confluence channels 209 that are connected to the first mixing chamber 202. The confluence channels 209 are inclined at the connection points with the first mixing chamber 202. The other ends of the two confluence channels 209 are connected to the low-temperature refrigeration box 18 and the high-temperature heating box 19 respectively through medium pipes.

[0035] Based on the above structure, the buffer impeller 203 buffers the impact force of the medium entering the mixing chamber, avoiding heat transfer fluctuations caused by sudden pressure changes. Together with the mixing spiral blades, it assists in the initial stirring of the medium, laying the foundation for subsequent uniform mixing. The mixing spiral blades 204, with their progressively decreasing diameter and pitch, adapt to the stepped mixing chamber space, enhancing the medium's shearing and mixing effects, ensuring uniform medium temperature and pressure, guiding smooth medium flow, reducing flow resistance, and improving circulation efficiency. The flow divider 207, with its triangular cross-section, achieves uniform medium distribution to each branch channel, avoiding excessive or insufficient flow in a single pipe. The 120° chamfer design reduces medium flow resistance, lowers energy loss, and ensures smooth flow distribution. The three stepped interconnected mixing chambers progressively optimize the medium flow pattern, providing reasonable space for mixing and buffering. The precise connection between the branch channels and the U-shaped circulation pipe ensures uniform medium distribution to each pipe, avoiding flow deviation. The medium from the cryogenic refrigeration box 18 or the high-temperature heating box 19 is transported to the inside of the collecting block 201 through the corresponding manifold 209. The connection between the manifold 209 and the first mixing chamber 202 is inclined, which can guide the medium to flow smoothly into the first mixing chamber 202 and avoid medium stagnation or poor flow. After the medium enters the first mixing chamber 202, it impacts the damped rotating buffer water wheel 203. The buffer water wheel 203 dampens the impact kinetic energy of the medium by rotating and preventing heat transfer fluctuations caused by sudden changes in medium pressure. At the same time, the rotation of the buffer water wheel 203 will drive the mixing spiral blade 204 extending into the second mixing chamber 205 to rotate synchronously. The diameter and pitch of the mixing spiral blade 204 decrease stepwise in the direction away from the buffer water wheel 203, which is suitable for the stepped spatial layout of the first mixing chamber 202, the second mixing chamber 205, and the third mixing chamber 206. During the rotation, the mixing spiral blade 204 forms a... The shearing and stirring action promotes thorough mixing of the medium, ensuring uniform temperature and pressure within the medium. Simultaneously, it guides the medium to flow smoothly into the third mixing chamber 206, reducing flow resistance losses. After further stabilization in the third mixing chamber 206, the medium flows to the branch channel 208 connected to the U-shaped circulation pipe 15. A triangular-section diverter block 207 at the midpoint of the connection between the branch channel 208 and the third mixing chamber 206 evenly distributes the medium to each branch channel 208, preventing excessive or insufficient flow in any single branch channel. Furthermore, the diverter block 207 has a 120° chamfer at its fixing point with the branch channel 208, reducing flow resistance, minimizing energy loss, and ensuring smooth diversion. Finally, the evenly diverted medium is precisely delivered to the corresponding U-shaped circulation pipe 15 through each branch channel 208, providing a uniformly temperature- and pressure-controlled medium for the three-dimensional heat transfer of the U-shaped circulation pipe 15, ensuring the uniformity and stability of workpiece heating or cooling. like Figure 2As shown, a mesh 12 is provided at the bottom of the test chamber 2 and below the fixed base 11. A sand collection hopper 23 is provided at the bottom of the test chamber 2. The side of the sand collection hopper 23 is tilted at an angle of 15° to facilitate the collection of sand particles. The bottom of the sand collection hopper 23 is connected to a sand collection box 24. A removable sand collection box 25 is provided on one side of the sand collection box 24.

[0036] The above structure facilitates the filtration and collection of sand, making it easy to reuse it later.

[0037] The testing machine also includes a temperature control mechanism, which consists of multi-point temperature sensors and a high-precision temperature controller. The multi-point temperature sensors are installed at the four corners inside the test chamber 2, on the top surface of the fixed base 11, and at the outlets of the U-shaped circulation pipe 15. They monitor the ambient temperature inside the test chamber 2, the sample surface temperature, and the temperature of the heat transfer medium in real time. The high-precision temperature controller uses a PID+fuzzy control algorithm and is electrically connected to the low-temperature refrigeration component and the high-temperature heating component. It can automatically adjust the refrigeration / heating power according to the set parameters, realize the custom control of the temperature cycle speed, and flexibly set any freeze-thaw cycle and total test time.

[0038] The working principle of this invention is as follows: Sample fixing: Place the sample to be tested on the fixing base 11, and fix the sample firmly by adjusting the position of the fixing piece 13 and the tightness of the screws to meet the sample size requirements; Parameter settings: The freeze-thaw cycle parameters (freezing temperature, thawing temperature, temperature cycle speed, freeze-thaw cycle, total test time, number of cycles) and wind and sand erosion parameters (nozzle angle 6, nozzle distance 6, sand output, jetting wind speed, erosion time) can be set via the capacitive screen of the display controller 27 (Chinese / English interface can be switched). The wind and sand erosion system is activated: the air compressor 9 is started to generate an airflow at the set pressure. When the airflow flows through the venturi tube 10, the sand particles in the conical discharge hopper 7 are sucked into the venturi tube 10 through the negative pressure port, forming a gas-solid two-phase flow. The servo motor 83 is started according to the instructions of the display screen controller 27, which drives the first gear 84 to rotate. The first gear 84 drives the meshing second gear 85 to rotate, which in turn drives the transmission shaft and baffle 82 to rotate, adjusting the opening and closing degree of the baffle 82. The flow sensor monitors the sand flow rate in real time and feeds it back to the display screen controller 27 to achieve precise control of the sand output. At the same time, the robotic arm 5 adjusts the angle and distance of the nozzle 6 according to the set parameters. The wind speed sensor monitors the spray wind speed in real time and feeds it back. The air compressor 9 dynamically adjusts the output air pressure to ensure that the spray wind speed is stable at the set value. The sand particles are sprayed onto the sample surface through the nozzle 6 to simulate the wind and sand erosion environment. The freeze-thaw cycle system is activated: Multi-point temperature sensors in the temperature control mechanism monitor various temperature data in real time and feed them back to the high-precision temperature controller. When heating is required, the high-precision temperature controller closes the solenoid valve connecting the low-temperature cooling chamber 18 to the circulation pump 17 and opens the solenoid valve connecting the high-temperature heating chamber 19 to the circulation pump 17. The circulation pump 17 starts, transporting the heat-conducting medium in the storage chamber 16 to the high-temperature heating chamber 19. The heated medium is distributed to each U-shaped circulation pipe 15 via the first collecting mechanism 20, heating the sample through the U-shaped circulation pipes 15. After heat exchange, the medium flows back to the storage chamber 16 via the second collecting pipe 21 and the return pipe 22, completing the heating cycle. When cooling is required, the solenoid valve corresponding to the high-temperature heating chamber 19 is closed, and the solenoid valve corresponding to the low-temperature cooling chamber 18 is opened. The circulation pump 17 transports the heat-conducting medium to the low-temperature cooling chamber 18 for cooling. The cooled medium cools the sample through the U-shaped circulation pipes 15, and after heat exchange, flows back to the storage chamber 16, completing the cooling cycle. By alternately switching between heating and cooling cycles, freeze-thaw cycle simulation is achieved. Test monitoring and sand recovery: During the test, the operator observed the changes in the surface state of the sample through the double-layered vacuum tempered glass of the box door; the falling sand particles were filtered by the strainer 12 and fell into the sand collection hopper 23, and were collected into the sand collection box 24 along the 15° inclined side, and finally collected into the sand collection box 25 for subsequent reuse. End of test: After the set total test time or number of cycles is reached, the equipment will automatically stop running. The operator should turn off the power and remove the sample for subsequent analysis.

[0039] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A wind and sand erosion freeze-thaw cycle test machine, comprising a support frame (1), characterized in that: The top of the support (1) is equipped with a test chamber (2), which is a sealed box structure; The bottom of the test chamber (2) is equipped with a sample fixing device, which can be adjusted to accommodate samples of different sizes by adjusting the position of the fixing piece (13) and the tightness of the screws; The test chamber (2) is equipped with a wind and sand erosion mechanism. A controllable airflow is generated by a pneumatic compressor (9) to form a gas-solid two-phase flow carrying sand particles in the wind and sand transport pipeline. The wind and sand flow with set wind speed and sand particle flow rate is sprayed onto the test sample by a nozzle (6) to simulate the real wind and sand erosion environment. The sample fixing device is equipped with a freeze-thaw cycle mechanism. Through the alternating operation of the low-temperature refrigeration chamber (18) and the high-temperature heating chamber (19), combined with the three-dimensional heat transfer of the circulation pipe (15), the temperature inside the test chamber can achieve temperature cycle change within a wide temperature range, which is used to simulate freeze-thaw conditions under extreme climate.

2. The wind and sand erosion freeze-thaw cycle test machine according to claim 1, characterized in that: The test chamber (2) has a double-layer insulation layer (3) on its inner side, and an aluminum foil reflective film (4) is sandwiched between the double-layer insulation layer (3).

3. The wind and sand erosion freeze-thaw cycle test machine according to claim 1, characterized in that: The sample fixing device includes a fixing seat (11) located at the bottom of the test chamber (2), and the top of the fixing seat (11) is provided with multiple fixing pieces (13) by screws.

4. The wind and sand erosion freeze-thaw cycle test machine according to claim 1, characterized in that: The wind and sand erosion mechanism includes a conical discharge hopper (7) set on the top of the test chamber (2), and the discharge end of the conical discharge hopper (7) extending into the test chamber (2) is provided with an adjustment mechanism (8). The top of the test chamber (2) is provided with a pneumatic compressor (9), and the output end of the pneumatic compressor (9) is connected to a venturi tube (10) through a pipe.

5. The wind and sand erosion freeze-thaw cycle test machine according to claim 1, characterized in that: The test chamber (2) is equipped with a robotic arm (5) on its inner side. The output end of the robotic arm (5) is equipped with a nozzle (6). The nozzle (6) is connected to the discharge end of the venturi tube (10) through a pipe.

6. The wind and sand erosion freeze-thaw cycle testing machine according to claim 4, characterized in that: The regulating mechanism (8) includes a throttling pipe (81) connected to the bottom of the conical discharge hopper (7). The bottom of the throttling pipe (81) is connected to the negative pressure port of the venturi tube (10) through a pipe. A drive shaft is rotatably installed inside the throttling pipe (81), and a baffle (82) is fixed on the outer wall of the drive shaft. The drive shaft extends to one end of the throttle tube (81) and is fixed with a second gear (85). The outer wall of the throttle tube (81) is provided with a servo motor (83). The output shaft of the servo motor (83) is fixed with a first gear (84) that meshes with the second gear (85). The diameter of the first gear (84) is smaller than the diameter of the second gear (85).

7. The wind and sand erosion freeze-thaw cycle testing machine according to claim 1, characterized in that: The freeze-thaw circulation mechanism includes an installation space set in a fixed base (11), a partition (14) is fixed on the inner side of the installation space, and a plurality of U-shaped circulation tubes (15) are arranged equidistantly above the partition (14). One end of each of the plurality of U-shaped circulation tubes (15) extends below the partition (14) and is connected to a first collecting mechanism (20), and the other ends of the plurality of U-shaped circulation tubes (15) extend below the partition (14) and are connected to a second collecting tube (21).

8. The wind and sand erosion freeze-thaw cycle test machine according to claim 7, characterized in that: A storage box (16) is fixed on one side of the bottom of the partition (14). A return pipe (22) connected to the second manifold (21) is connected to one side of the storage box (16). A circulation pump (17) is provided at the bottom of the partition (14) on one side of the storage box (16), and the circulation pump (17) is connected to the storage box (16) through a medium pipe.

9. The wind and sand erosion freeze-thaw cycle test machine according to claim 7, characterized in that: The bottom of the partition (14) and the side of the circulating pump (17) are provided with a low-temperature refrigeration box (18) and a high-temperature heating box (19). The inlets of the low-temperature refrigeration box (18) and the high-temperature heating box (19) are connected to the outlet of the circulating pump (17) through a medium pipe. Electromagnetic valves are provided on the medium pipes connecting the low-temperature refrigeration box (18) and the high-temperature heating box (19) to the circulating pump (17). The discharge ports of the low-temperature refrigeration box (18) and the high-temperature heating box (19) are connected to the first collecting mechanism (20) through the medium pipes.

10. The wind and sand erosion freeze-thaw cycle testing machine according to claim 1, characterized in that: The first gathering mechanism (20) includes a gathering block (201), which has three mixing chambers arranged in a stepped manner and connected to each other. The mixing chambers are arranged in descending order of diameter as the first mixing chamber (202), the second mixing chamber (205), and the third mixing chamber (206). A damped water wheel (203) is installed on one side of the first mixing chamber (202). One end of the buffer water wheel (203) is located in the second mixing chamber (205) and is provided with a mixing spiral blade (204). The diameter and pitch of the mixing spiral blade (204) decrease step by step in the direction away from the buffer water wheel (203). The inside of the collecting block (201) is provided with a branch channel (208) that communicates with the third mixing chamber (206). The branch channel (208) is connected to one end of the U-shaped circulation pipe (15). The middle part of the connection between the branch channel (208) and the third mixing chamber (206) is provided with a diversion block (207) with a triangular cross section. The diversion block (207) and the branch channel (208) are fixed with a 120° chamfer. The inside of the collecting block (201) is provided with two confluence channels (209) that are connected to the first mixing chamber (202), and the first mixing chamber (202) of the confluence channel (209) is inclined. The other ends of the two confluence channels (209) are connected to the low temperature refrigeration box (18) and the high temperature heating box (19) respectively through medium pipes.

Images