A testing device, testing method and processing technology for liquid nitrogen environment

Abstract

This application discloses a testing device, testing method, and processing technology for use in a liquid nitrogen environment, relating to the field of cryogenic testing technology. The device includes a liquid nitrogen tank for providing a liquid nitrogen environment; a testing turntable disposed within the liquid nitrogen tank for placing the test piece; a driving mechanism including a driving motor for driving the testing turntable to rotate; and a cryogenic protection device including a protective shell and a sealing connecting sleeve disposed within the protective shell, forming an isolation cavity between the protective shell and the sealing connecting sleeve. The sealing connecting sleeve is used to install the driving end of the driving motor, thus protecting the driving end of the driving motor. In a liquid nitrogen testing environment, the protective shell, the pressure barrier formed by the isolation cavity, and the sealing connecting sleeve provide multiple layers of protection for the driving motor, reducing the possibility of liquid nitrogen leakage and water vapor infiltration into the driving motor.

Description

Technical Field

[0001] This application relates to the field of cryogenic testing technology, and in particular to a testing device, testing method and processing technology for use in a liquid nitrogen environment. Background Technology

[0002] Precision positioning and rotating platforms in liquid nitrogen environments are core equipment in the field of cryogenic testing. They need to achieve high-precision rotational positioning at an extreme low temperature of -196°C to provide stable support for the cryogenic performance testing of specimens and the measurement of equipment structural dimensions. However, existing technologies have many intractable drawbacks in practical applications. For example, in existing liquid nitrogen environment testing devices, the motors are not effective at blocking the conduction of cryogenic temperatures, which can easily lead to the failure of electronic components.

[0003] Therefore, there is a need to provide a testing device, testing method, and processing technology for use in a liquid nitrogen environment, which can ensure the normal and stable operation of the motor in a liquid nitrogen environment. Summary of the Invention

[0004] The main purpose of this application is to provide a testing device, testing method and processing technology for use in liquid nitrogen environment, which aims to solve the technical problem that motors are difficult to effectively block low temperature conduction in existing liquid nitrogen environment tests, which easily leads to the failure of electronic components.

[0005] To achieve the above objectives; In a first aspect, this application discloses a testing device for use in a liquid nitrogen environment, characterized in that it comprises: Liquid nitrogen tank, the liquid nitrogen tank being used to provide a liquid nitrogen environment; A test turntable, which is set inside a liquid nitrogen bath, is used to place the test piece; A drive mechanism, the drive mechanism including a drive motor, the drive motor being used to drive the test turntable to rotate; A low-temperature protection device includes a protective housing and a sealing connecting sleeve disposed within the protective housing. An isolation cavity is formed between the protective housing and the sealing connecting sleeve. The sealing connecting sleeve is used to install the drive end of a drive motor to enclose and protect the drive end of the drive motor.

[0006] Optionally, it also includes a temperature adaptive adjustment mechanism disposed within the protective housing. The temperature adaptive adjustment mechanism includes multiple temperature sensors and a heating device. The multiple temperature sensors are respectively disposed within the isolation cavity, on the drive motor housing, and on the drive motor windings. The heating device is disposed on the protective housing and is electrically connected to the temperature sensors on the drive motor housing to adjust the temperature of the drive motor.

[0007] Optionally, the protective housing is further provided with an air inlet pipe and an exhaust pipe. The air inlet pipe is used to connect with an external inert gas supply device to inject inert gas into the isolation chamber, and the exhaust pipe is used to discharge the inert gas in the isolation chamber.

[0008] Optionally, the inner wall of the protective shell is provided with a heat insulation layer, and the outer wall of the protective shell is provided with a thermal insulation layer.

[0009] Optionally, it also includes a transmission mechanism, which includes a mounting frame and a transmission shaft mounted on the mounting frame. The transmission shaft is used to drive the test turntable to rotate. The drive mechanism also includes a support frame and a drive shaft that is driven by the drive end of a drive motor. The drive motor and the drive shaft are mounted on the support frame, and the transmission shaft and the drive shaft are provided with meshing bevel gears.

[0010] Optionally, the test turntable includes a bearing turntable and a support platform disposed on the bearing turntable. The support platform is used to place the test piece. The transmission mechanism also includes a transmission worm gear disposed on the mounting bracket. The transmission worm gear is connected to a transmission shaft and is in transmission cooperation with the bearing turntable to drive the bearing turntable to rotate.

[0011] Secondly, this application also discloses a testing method for use in a liquid nitrogen environment, based on the aforementioned testing apparatus for use in a liquid nitrogen environment, comprising the following steps: Fix the test piece on the support platform, connect the testing device to the external control system, and inject liquid nitrogen into the liquid nitrogen tank to the preset level; The external control system is activated, and pre-cooling is performed according to the preset cooling rate. The temperature adaptive adjustment mechanism keeps the drive motor temperature between -50℃ and 10℃. The temperature of the turntable surface to be tested reaches -196℃ and remains stable within the preset time, ready to start the test. The rotation angle and speed of the test turntable are controlled by an external control system. After the test is completed, the temperature is increased at the preset heating rate. After the temperature of the test turntable returns to room temperature, the power is turned off, the test piece is removed, and the residual liquid nitrogen and surface impurities in the liquid nitrogen tank are cleaned.

[0012] Thirdly, this application also discloses a processing technology for a testing device in a liquid nitrogen environment, which includes the following steps: The target parts are forged and rough machined sequentially to near the finished size, and then carburized and quenched or tempered according to the purpose of the target parts. The target parts include bearing turntable, bearing table, transmission shaft, drive shaft, transmission worm gear and bevel gear. The target part is subjected to three cycles of deep cryogenic treatment according to the preset process parameters. After each deep cryogenic cycle, the key dimensions of the target part are sampled and inspected to ensure that the deformation meets the design requirements. The transmission worm and transmission shaft are precision ground with diamond grinding wheels to control coaxiality and surface roughness; the bevel gears are precision ground to control meshing clearance; and the threaded pairs are sprayed with a composite coating to improve low-temperature lubrication performance. After pre-cooling the outer ring of the turntable bearing to -80℃, cold assembly is performed. After assembly, a 2-hour running-in test is conducted at a speed of 1° / s to ensure that the bearing friction torque meets the standard. The low-temperature protection housing of the drive motor is installed, and the sealing status of the isolation chamber and the connection between the temperature sensor and the adjustment system are checked to ensure proper assembly. Inert gas is then injected into the isolation chamber. Under normal temperature conditions, the positioning accuracy and repeatability of the bearing turntable are calibrated. Then, liquid nitrogen is injected into the liquid nitrogen bath and pre-cooled at a preset cooling rate. Once the turntable surface temperature reaches -196℃ and remains stable within a preset time, the transmission smoothness, self-locking performance, and the operating status of the drive motor protection structure are tested.

[0013] Optionally, the step of performing three cycles of deep cryogenic treatment on the target part according to preset process parameters includes the following steps: The target part was immersed in liquid nitrogen at -196℃ for 4 hours and then allowed to recover naturally at an ambient temperature of 20±5℃. Then the target part was immersed in liquid nitrogen at -196℃ for 6 hours, and then gradually warmed up in three stages: -100℃, -50℃ and 0℃, with each stage held for 4 hours. The target part is then immersed in liquid nitrogen at -196°C for 8 hours, kept at a constant temperature of 120°C for 8 hours, and then subjected to low-temperature tempering at 200°C for 2 hours.

[0014] Optionally, calibrating the positioning accuracy and repeatability of the bearing turntable includes the following steps: The positioning accuracy and repeatability were tested using a laser interferometer at 10° intervals from 0° to 360°, and the baseline data were recorded. The test turntable was cooled to -196℃ and remained stable for a preset time. The room temperature calibration procedure was then repeated. Multiple stages of hot and cold cycling were completed, with the number of cycles gradually increasing in each stage. After each stage, the temperature was kept at -196℃ for 2 hours and then placed at room temperature for 2 hours before accuracy retesting was performed. The test of transmission smoothness, self-locking performance, and the operating status of the drive motor protection structure includes the following steps: At -196℃, the bearing turntable was continuously operated at a speed of 1° / s and under load for 8 hours to monitor the status of the drive motor, sealing performance and transmission. At both room temperature and -196℃, multiple loads of different weights were applied to the test turntable to test positioning accuracy, self-locking performance, and vibration. Liquid nitrogen was injected into the liquid nitrogen tank to the preset level, and the sealing performance of the protective shell was continuously monitored for 4 hours. The target part was subjected to low-temperature hardness test, low-temperature impact test, and dimensional stability test in sequence.

[0015] The beneficial effects achieved by this application are as follows: Under liquid nitrogen testing environment, the pressure barrier formed by the protective shell and isolation cavity and the sealed connection sleeve provide multiple protections for the drive motor, reducing the possibility of liquid nitrogen leakage and water vapor infiltration into the drive motor, enhancing the reliability of the drive motor operation, effectively solving the problem of drive motor failure in liquid nitrogen environment, and having the advantages of effectively isolating low temperature conduction, protecting the stable operation of drive motor in liquid nitrogen environment, and improving the reliability and service life of equipment. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1 This is a schematic diagram of the structure of a testing device for use in a liquid nitrogen environment, as described in an embodiment of this application. Figure 1 ; Figure 2 This is a schematic diagram of the structure of a testing device for use in a liquid nitrogen environment, as described in an embodiment of this application. Figure 2 ; Figure 3 This is a schematic diagram of the structure of a cryogenic protection device in a testing apparatus for use in a liquid nitrogen environment, as described in an embodiment of this application. Figure 4 This is a flowchart of a cyclic cryogenic treatment process in the manufacturing process of a testing device used in a liquid nitrogen environment, as described in the embodiments of the application.

[0018] Figure label: 1-Bearing turntable, 2-Bearing platform, 3-Drive shaft, 4-Drive worm gear, 5-Support frame, 6-Drive motor, 7-Drive shaft, 8-Bevel gear, 9-Protective housing, 10-Sealing connection sleeve, 11-Liquid nitrogen tank, 12-Inlet pipe, 13-Exhaust pipe, 14-Insulation layer, 15-Heat insulation layer, 16-Conduit, 17-Mounting bracket, 18-Heating element.

[0019] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0024] Example See attached document Figure 1-4This embodiment provides a testing device for a liquid nitrogen environment, including a liquid nitrogen tank 11, a test turntable, a drive mechanism, and a cryogenic protection device. The liquid nitrogen tank 11 provides a liquid nitrogen environment; the test turntable is disposed in the liquid nitrogen tank 11 and is used to place the test piece; the drive mechanism includes a drive motor 6, which drives the test turntable to rotate; the cryogenic protection device includes a protective shell 9 and a sealing connecting sleeve 10 disposed in the protective shell 9, forming an isolation cavity between the protective shell 9 and the sealing connecting sleeve 10, and the sealing connecting sleeve 10 is used to install the drive end of the drive motor 6 to wrap and protect the drive end of the drive motor 6.

[0025] In this embodiment, the drive motor 6 is a 1.5kW cryogenic servo motor with a rated speed of 3000rpm and a transmission ratio of 1:100. Multiple fixing holes for fixing the test piece are provided on the test turntable. Liquid nitrogen is injected into the liquid nitrogen tank 11 to the preset liquid level. In this embodiment, the liquid nitrogen injection volume is 20L. At the same time, a heat insulation layer 15 is provided in the liquid nitrogen tank 11. The thickness of the heat insulation layer 15 is more than 50mm. The protective shell 9 is made of 304 stainless steel, and the sealing connection sleeve 10 is made of low-temperature resistant silicone rubber. At the connection between the drive motor 6 and the protective shell 9, sealing materials and a clamping flange are used to ensure uniform pressure on the sealing surface, reduce liquid nitrogen leakage and external water vapor infiltration, and protect the internal electronic components of the drive motor 6.

[0026] The main function of the liquid nitrogen tank 11 is to provide and maintain a stable liquid nitrogen environment. The liquid nitrogen tank 11 can be a container with good thermal insulation performance, such as a Dewar flask-type container with a double-wall structure and filled with vacuum or thermal insulation material, to reduce heat transfer and thus effectively reduce the evaporation rate of liquid nitrogen. In another implementation, the liquid nitrogen tank 11 can be a single-layer metal container, which achieves the thermal insulation effect by wrapping the outside with thermal insulation material.

[0027] The following example will provide a more detailed explanation of the above technical solution: The test piece is placed securely on the test turntable of the test device. Then, liquid nitrogen is injected into the liquid nitrogen tank 11 until the preset liquid level is reached. At this time, an extremely low temperature environment of -196°C is formed inside the liquid nitrogen tank 11.

[0028] During the test, the drive motor 6 of the drive mechanism needs to run continuously to drive the test turntable to rotate. Since the drive motor 6 is sensitive to low temperature environment, direct exposure to liquid nitrogen environment will cause its performance to degrade or even be damaged. The low temperature protection device of this embodiment plays a key role here. The drive end of the drive motor 6 is installed in the sealing connecting sleeve 10, and the sealing connecting sleeve 10 is wrapped by the protective shell 9. An isolation cavity is formed between the protective shell 9 and the sealing connecting sleeve 10. This isolation cavity effectively isolates the drive end of the drive motor 6 from the extremely low temperature environment in the liquid nitrogen tank 11.

[0029] When the drive motor 6 starts, the rotational power it generates is transmitted to the test turntable through the drive end. After receiving the power, the test turntable begins to rotate precisely, thereby driving the test piece on the test turntable to rotate in the liquid nitrogen environment. Throughout the process, the low temperature protection device ensures that the drive end of the drive motor 6 operates in a relatively stable temperature environment, avoiding performance degradation or failure caused by extremely low temperature.

[0030] Therefore, it is possible to perform precise rotational testing of materials in a liquid nitrogen environment. At the same time, the low temperature protection device effectively solves the reliability problem of the drive motor 6 operating in an extremely low temperature environment. The liquid nitrogen tank 11 provides a stable low temperature environment, the test turntable carries and rotates the test piece, the transmission mechanism transmits power, the drive mechanism provides the power source, and the low temperature protection device ensures the normal operation of the drive mechanism under extreme conditions. All components work together to complete the low temperature testing task.

[0031] Therefore, the testing device provided in this embodiment demonstrates a significant technical contribution in solving the problems of the prior art. In the prior art, the protection structure of the drive motor 6 is usually relatively simple, using only a simple seal or a single-layer heat insulation layer 14. This makes the drive motor 6 susceptible to low temperature in the liquid nitrogen environment, which in turn causes problems such as electronic component failure, liquid nitrogen leakage or external water vapor infiltration, seriously affecting the reliable operation of the drive unit.

[0032] In contrast, the testing apparatus of this embodiment effectively solves the above-mentioned problems by setting up a low-temperature protection device. The low-temperature protection device includes a protective shell 9 and a sealing connecting sleeve 10, which form an isolation cavity. This double-layer structure and isolation cavity design can more effectively isolate the drive end of the drive motor 6 from the extremely low temperature liquid nitrogen environment. In the above test, even if the internal temperature of the liquid nitrogen tank 11 is as low as -196°C, the drive end of the drive motor 6 can still be effectively protected by the isolation cavity, avoiding direct exposure to extreme low temperature. This structure not only enhances the barrier to low temperature conduction, but also improves the overall sealing performance, thereby significantly reducing the risk of liquid nitrogen leakage and external water vapor infiltration.

[0033] Therefore, the cryogenic protection device in this embodiment provides a more stable and reliable operating environment for the drive motor 6, ensuring the long-term stable operation of the drive motor 6 in the liquid nitrogen environment, and significantly improving the overall reliability and service life of the testing device.

[0034] As an optional implementation, a temperature adaptive adjustment mechanism is also included within the protective housing 9. This mechanism includes multiple temperature sensors and a heating device. Multiple temperature sensors are respectively located within the isolation cavity, on the drive motor 6 housing, and on the drive motor 6 windings. The heating device is located on the protective housing 9. The protective housing 9 also has a conduit 16 for leading out the data lines of the temperature sensors and the heating device. The heating device is electrically connected to the temperature sensors on the drive motor 6 housing to adjust the temperature within the protective housing 9. In this embodiment, the heating device is a heating element 18, a 500W, 220V annular heating element installed on the inner wall of the protective housing 9. By monitoring the temperature at three points—the isolation cavity, the drive motor 6 housing, and the drive motor 6 windings—using the temperature sensors, the operating environment temperature of the drive motor 6 can be widely monitored. The monitored temperature data is transmitted to an externally connected control system. When the temperature on the drive motor 6 housing is lower than... When the temperature reaches 40°C, the heating element 18 is activated. The control system transmits data to the heating element 18, which then heats the motor to raise the temperature. This controls the operating environment temperature of the drive motor 6 between -50°C and 10°C. In this embodiment, the optimal temperature range for the outer casing of the drive motor 6 is between -35°C and 5°C, which controls the operating environment temperature of the drive motor 6 and reduces the possibility of low-temperature failure.

[0035] In this embodiment, the heating device is a component used to generate heat to raise the local or overall temperature. The device can be in the form of an electric heating film or heating plate 18, which is directly attached to the surface to be heated, and has the characteristics of uniform heating and fast response; or it can be a resistance heating wire, which provides a concentrated heat source by winding or arranging it in a specific area; or it can be a positive temperature coefficient heater, which has self-limiting temperature characteristics and can effectively prevent overheating.

[0036] Temperature sensors are installed inside the isolation chamber, on the housing of the drive motor 6, and on the windings of the drive motor 6. These sensors are designed to comprehensively monitor the temperature of the drive motor 6 and its surrounding environment. The sensor inside the isolation chamber monitors the overall ambient temperature of the isolation chamber, reflecting the insulation effect of the low-temperature protection device. The temperature sensors can be resistance temperature detectors, such as Pt100 or Pt1000. The sensor on the housing of the drive motor 6 monitors the surface temperature of the motor body, a crucial indicator of the motor's operating status. The sensor on the windings of the drive motor 6 directly monitors the temperature of the motor's core heat-generating components, which is essential for preventing the motor from becoming too cold or too hot. A heating device is installed on the protective housing 9, allowing it to radiate heat into the isolation chamber, thereby indirectly and evenly heating the drive motor 6 and avoiding the risk of localized overheating that could result from direct contact.

[0037] The heating device is electrically connected to the temperature sensor on the housing of the drive motor 6, which means that the operating status of the heating device is controlled by the temperature signal measured by the temperature sensor on the housing of the drive motor 6. This connection method ensures that the heating system can respond according to the actual thermal state of the drive motor 6 and achieve precise temperature regulation. The purpose of regulating the temperature of the drive motor 6 is to maintain the operating temperature of the drive motor 6 within its optimal range allowed by its design, thereby ensuring that the motor can still operate stably and efficiently in extreme low temperature environments and avoid performance degradation or component damage caused by low temperature.

[0038] The temperature adaptive adjustment mechanism can be controlled by a microcontroller as the core control unit. Multiple temperature sensors monitor the temperature of the drive motor 6 and its surrounding environment in real time at multiple points. Specifically, temperature sensors located inside the isolation chamber monitor the overall temperature of the isolation chamber, temperature sensors on the drive motor 6 housing monitor the surface temperature of the motor body, and temperature sensors on the drive motor 6 windings monitor the temperature of the most critical internal components. These sensors transmit their respective temperature signals to the control unit. When the control unit receives a temperature reading from the temperature sensor on the drive motor 6 housing that is lower than a preset lower limit, it activates the heating device located on the protective housing 9. The heating device begins to work, releasing heat into the isolation chamber to raise its temperature, thereby heating the drive motor 6. As the temperature of the drive motor 6 rises, when the temperature reading from the temperature sensor on the drive motor 6 housing reaches a preset upper limit, the control unit stops the heating device. Through this closed-loop feedback control mechanism, the temperature adaptive adjustment mechanism can dynamically respond to the low temperature effect of the liquid nitrogen environment and accurately maintain the temperature of the drive motor 6 within a suitable working range. This effectively avoids problems such as performance degradation, component embrittlement, or lubrication failure caused by overcooling of the motor, thereby ensuring the stable operation of the transmission mechanism and the test turntable and improving the reliability and test accuracy of the entire test device under extreme low temperature conditions.

[0039] As an optional implementation, the protective housing 9 is also provided with an air inlet pipe 12 and an exhaust pipe 13. The air inlet pipe 12 is used to connect with an external inert gas supply device to inject inert gas into the isolation chamber, and the exhaust pipe 13 is used to discharge the inert gas in the isolation chamber. In this embodiment, inert nitrogen is used as the inert gas. In other embodiments, inert gases such as argon and helium can also be used. The purity of nitrogen is ≥99.99%, and the pressure in the isolation chamber is maintained at 0.12~0.15MPa.

[0040] Before the device is put into use in a liquid nitrogen environment, external inert gas is injected into the isolation chamber through the inlet pipe 12, while the original air and water vapor in the isolation chamber are discharged through the exhaust pipe 13. This process can be repeated to ensure that the air and water vapor in the isolation chamber are fully replaced, forming a dry, oxygen-free, and non-condensing inert gas environment. After the isolation chamber is filled with inert gas, its internal environment is stable. As an insulating medium, the inert gas can effectively prevent the cold energy of the external liquid nitrogen environment from being transferred to the drive motor 6, while avoiding the impact of air condensation and frost on the insulation performance. When the drive motor 6 is working, even if it generates a small amount of heat, the temperature adaptive adjustment mechanism can accurately sense it through the temperature sensor and make precise adjustments by the heating device. The inert gas environment ensures the normal operation of the sensor and the heating device without being affected by ice and frost. Therefore, through the introduction and discharge of inert gas, the microenvironment in the isolation chamber is optimized, providing a reliable guarantee for the long-term stable operation of the drive motor 6 at extremely low temperatures.

[0041] The specific implementation method is as follows: The inlet pipe 12 is connected to an external inert gas supply source, such as a high-pressure nitrogen cylinder. The injection volume and flow rate of nitrogen are precisely controlled by a pressure reducing valve and a flow meter. The exhaust pipe 13 can be connected to an exhaust port, which can be connected to the environment or an exhaust gas collection system. A one-way valve can be installed to prevent backflow of external air. During the pre-cooling stage or before the equipment is started, the operator can open the valve on the inlet pipe 12 to allow nitrogen to slowly flow into the isolation chamber. At the same time, the valve on the exhaust pipe 13 is opened to allow the air in the chamber to be gradually pushed out by nitrogen. When the preset purging time or gas replacement volume is reached, the valve on the exhaust pipe 13 can be closed, and the inert gas in the isolation chamber is kept in a slightly positive pressure state to further reduce the possibility of external air infiltration.

[0042] As an optional implementation, the inner wall of the protective housing 9 is provided with a heat insulation layer 14, and the outer wall of the protective housing 9 is provided with a heat insulation layer 15. The thickness of the heat insulation layer 14 is more than 30 mm, and the thickness of the heat insulation layer 15 is more than 50 mm. The function of the heat insulation layer 14 is to reduce the heat exchange between the interior of the protective housing 9 and the isolation cavity, thereby reducing heat loss or the transfer of external heat into the isolation cavity. The heat insulation layer 14 can be implemented in various ways. For example, a vacuum interlayer can be formed between the inner wall of the protective housing 9 and the sealing connecting sleeve 10, utilizing the low thermal conductivity of the vacuum for heat insulation; or, multilayer reflective heat insulation materials, such as... Multi-layer aluminum-coated film achieves thermal insulation by reflecting radiant heat; alternatively, it can be filled with materials with low thermal conductivity, such as aerogel, polyurethane foam, or fiberglass; the insulation layer 15 is used to reduce heat exchange with the external environment, further reducing heat exchange between the protective shell 9 and the external liquid nitrogen environment, thereby maintaining the stability of the internal temperature of the protective shell 9. The insulation layer 15 can be made of materials with good thermal insulation properties, such as polyurethane foam, glass wool, or rock wool. These materials contain a large amount of air, which can effectively reduce heat conduction; or a vacuum insulation panel can be used, which provides excellent thermal insulation through a vacuum-sealed core material.

[0043] A heat insulation layer 14 is installed on the inner wall of the protective shell 9, effectively reducing heat exchange between the isolation cavity and the main body of the protective shell 9. This allows the temperature adaptive regulation mechanism to maintain the temperature of the drive end of the drive motor 6 more efficiently and accurately. Simultaneously, a heat insulation layer 15 is installed on the outer wall of the protective shell 9, further isolating the protective shell 9 from the external liquid nitrogen environment, significantly reducing the impact of the extremely low external temperature environment on the internal temperature of the protective shell 9. This dual internal and external heat insulation design creates a highly insulated microenvironment, greatly reducing the heat load, enabling the drive motor 6 to operate stably in the liquid nitrogen environment, and reducing the energy consumption required for temperature regulation.

[0044] As an optional implementation, a transmission mechanism is also included. The transmission mechanism includes a mounting frame 17 and a transmission shaft 3 mounted on the mounting frame 17. The transmission shaft 3 is used to drive the test turntable to rotate. The drive mechanism also includes a support frame 5 and a drive shaft 7 that is driven by the drive end of the drive motor 6. The drive motor 6 and the drive shaft 7 are mounted on the support frame 5. The transmission shaft 3 and the drive shaft 7 are provided with meshing bevel gears 8. In other embodiments, the transmission engagement between the drive shaft 7 and the transmission shaft 34 can also adopt a worm gear structure. The support frame 5 is fixed to the wall of the liquid nitrogen tank 11 and extends out of the liquid nitrogen tank 11 at its top. The drive motor 6 is mounted at the top of the support frame 5, so that the drive motor 6 can be kept away from the liquid nitrogen in the liquid nitrogen tank 11, optimizing the working environment of the drive motor 6 and reducing the possibility of liquid nitrogen intruding into the drive motor 6.

[0045] As an optional implementation, the test turntable includes a bearing turntable 1 and a support platform 2 disposed on the bearing turntable 1. The support platform 2 is used to place the test piece. The transmission mechanism also includes a transmission worm gear 4 disposed on the mounting frame 17. The transmission worm gear 4 is connected to the transmission shaft 3 and is in transmission cooperation with the bearing turntable 1 to drive the shaft 7 to rotate the turntable 1.

[0046] By mounting the drive motor 6 on the support frame 5 on the wall of the liquid nitrogen tank 11, and protecting its drive end with a cryogenic protection device, the drive end of the drive motor 6 is connected to the drive shaft 7. The bevel gear 8 on the drive shaft 7 meshes with the bevel gear 8 on the transmission shaft 3, thereby transmitting the rotational power of the drive motor 6 to the transmission shaft 3 and changing the transmission direction. The transmission shaft 3 further transmits the power to the transmission worm gear 4 mounted on the mounting bracket 17. The transmission worm gear 4 is in transmission engagement with the bearing turntable 1, driving the bearing turntable 1 to rotate. This transmission chain design allows the drive motor 6 to rotate relatively... Operating in a mild environment, the transmission direction can be flexibly changed through the bevel gear 8, making the layout of the drive mechanism and transmission mechanism more compact and reasonable. The cooperation between the transmission worm 4 and the bearing turntable 1 not only provides a large reduction ratio and torque increase effect, but more importantly, it utilizes the self-locking characteristics of the worm gear transmission to ensure the high-precision positioning and stability of the bearing turntable 1 in the stopped state, effectively avoiding positioning deviations caused by vibration or external interference in the liquid nitrogen environment. The entire transmission system optimizes the structural layout while ensuring high precision and stability, adapting to the special requirements of the liquid nitrogen environment.

[0047] In response, this application further proposes a testing method for use in a liquid nitrogen environment, comprising the following steps: S1. Preparation stage: Fix the test piece on the support platform 2, connect the test device to the external control system, and at the same time check the sealing status between the drive motor 6 and the protective shell 9, the connection status of the temperature sensor, and inject liquid nitrogen into the liquid nitrogen tank 11 to the preset liquid level. During preparation, the test piece is fixed on the support platform 2 to ensure its stable position during testing and to prevent it from falling off or shifting due to vibration or rotation. The fixing method can be bolt fixing, clamp clamping, vacuum adsorption, etc. Connecting the testing device to the external control system is to realize remote control, data acquisition and automated operation of the testing device. The connection can be wired or wireless. Liquid nitrogen is injected into the liquid nitrogen tank 11 to the preset liquid level. The purpose is to provide the required extremely low temperature environment for testing. Liquid nitrogen injection can be achieved through an automatic liquid nitrogen injection system or by manual injection.

[0048] S2, Pre-cooling stage: Start the external control system and pre-cool according to the preset cooling rate of 5℃ / min. The temperature adaptive adjustment mechanism keeps the temperature of the drive motor 6 at -50℃ to -10℃. The temperature of the test turntable reaches -196℃ and remains stable within a preset time. In this embodiment, the temperature of the test turntable needs to be kept at -196℃ for 10 minutes to prepare for the start of the test. Pre-cooling at a preset cooling rate gradually lowers the test environment temperature, effectively preventing thermal shock damage to the equipment and test pieces caused by sudden temperature drops. The external control system can control the cooling rate by precisely adjusting the liquid nitrogen injection volume or controlling the exhaust rate of the liquid nitrogen tank 11 according to a preset program. A temperature adaptive adjustment mechanism maintains the drive motor 6 temperature between -50℃ and 10℃, protecting it for normal operation in extremely low temperatures and preventing performance degradation or damage due to excessively low temperatures. This mechanism receives real-time temperature data from temperature sensors and precisely controls the power output of the heating device to maintain the drive motor 6 temperature within the target range. Once the test turntable surface temperature reaches -196℃ and remains stable for a preset time, the test is ready to begin. This ensures the test environment reaches and stabilizes at the extremely low temperature of liquid nitrogen, meeting the stringent testing requirements. This is typically achieved by real-time temperature monitoring using temperature sensors located near the test turntable surface. When the temperature reaches -196℃ and remains stable for a period of time with fluctuations within ±1℃, the environment is considered stable, and the test can begin.

[0049] S3. Testing Phase: The rotation angle and speed of the test turntable are controlled by the external control system to start the test. At the same time, relevant data of the test piece are collected through the entire test system during the test, and the equipment operation status is monitored in real time by the external control system. The rotation angle and speed of the test turntable are controlled by an external control system. The purpose is to achieve precise motion control of the test piece, thereby simulating actual working conditions or executing specific test trajectories. The external control system sends instructions to the drive mechanism, and the drive motor 6 drives the transmission mechanism according to these instructions, thereby precisely controlling the rotation angle and speed of the bearing turntable 1.

[0050] S4. End stage: After the test is completed, the temperature is increased at the preset heating rate of 5℃ / min. After the temperature of the test turntable returns to room temperature, the power of the equipment is turned off, the test piece is taken out, the residual liquid nitrogen in the liquid nitrogen tank 11 and the impurities on the surface of the equipment are cleaned, the status of each component of the equipment is checked and maintenance records are made. After the test, the temperature is increased at a preset rate to gradually raise the ambient temperature and avoid thermal shock to the equipment and test pieces caused by sudden temperature increases. The external control system controls the heating rate by stopping the liquid nitrogen supply and using auxiliary heating or natural rewarming. Once the test turntable surface temperature has returned to room temperature, the equipment power is turned off, the test piece is removed, residual liquid nitrogen in the liquid nitrogen tank 11 and impurities on the equipment surface are cleaned, and the condition of each component is checked and maintenance records are made. This is to complete the post-test equipment recovery and maintenance work to ensure that the equipment can operate normally the next time it is used.

[0051] The aforementioned testing methods enable the systematic and standardized operation of testing equipment in liquid nitrogen environments, effectively solving the problems of complex equipment operation, difficult temperature control, and susceptibility to damage to key components when testing in extremely low-temperature environments. In particular, the precise maintenance of the drive motor 6 temperature through temperature reduction rate control during the pre-cooling stage and the temperature adaptive adjustment mechanism significantly reduces the potential thermal shock and cryogenic damage to the equipment during the transition from room temperature to -196℃ liquid nitrogen, ensuring the stability and reliability of the drive motor 6 under extreme conditions. Furthermore, clearly defined testing and termination stages ensure the accuracy and repeatability of the testing process, extend the equipment's lifespan, and improve testing efficiency and safety.

[0052] This application also proposes a processing technology for a testing device in a liquid nitrogen environment, including the following steps: Pre-treatment of target parts: The transmission worm 4, transmission shaft 3 and drive shaft 7 are all made of 9Cr18 steel. The turntable bearing is made of 9Cr18 steel inner and outer rings and ceramic rolling elements. The bevel gear 8 is made of 20CrMnTi steel. The target parts are forged and rough machined to near the finished size. Then, depending on the use of the target parts, they are carburized and quenched or tempered. The carburizing and quenching temperature is 920℃ and the time is 4 hours. The tempering process is quenching at 860℃ plus tempering at 580℃. The target parts include the bearing turntable 1, the bearing platform 2, the transmission shaft 3, the drive shaft 7, the transmission worm 4 and the bevel gear 8. The pretreatment steps for target parts aim to improve the internal structure of the material and enhance its mechanical properties, such as strength, hardness, and toughness, through plastic deformation and heat treatment, laying the foundation for subsequent precision machining and stable operation in low-temperature environments. Forging can refine the grains and eliminate casting defects; rough machining provides dimensional allowances for subsequent finish machining; carburizing and quenching or tempering treatments impart high hardness, high wear resistance, or good comprehensive mechanical properties to the target part, depending on its specific functional requirements. For example, forging can employ free forging or die forging processes, rough machining can use turning, milling, etc., while carburizing and quenching can involve gas carburizing or solid carburizing followed by quenching, and tempering treatments typically include quenching and high-temperature tempering.

[0053] Composite cryogenic treatment: Perform three cycles of cryogenic treatment on the target part according to the preset process parameters. After each cryogenic cycle, conduct random checks on the key dimensions of the target part to ensure that the deformation meets the design requirements. The three-cycle cryogenic treatment process is as follows: First cycle: Immerse the target part in liquid nitrogen at -196℃ for 4 hours, then allow it to recover naturally at an ambient temperature of 20±5℃; Second cycle: Then immerse the target part in liquid nitrogen at -196℃ for 6 hours, and then gradually warm it up in three stages: -100℃, -50℃, and 0℃, with each stage held for 4 hours. The third cycle: The target part is then immersed in liquid nitrogen at -196°C for 8 hours, kept at 120°C for 8 hours, and then subjected to low-temperature tempering at 200°C for 2 hours.

[0054] Traditional cryogenic rotating platforms rely solely on single cryogenic treatment for their core components, resulting in insufficient residual stress release (typically less than or equal to 70%). Repeated thermal cycles easily lead to dimensional drift and excessive deformation, causing a rapid decline in positioning accuracy and failing to meet the demands of long-term precision measurement. Cyclic cryogenic treatment aims to optimize the material's microstructure and improve its mechanical properties and dimensional stability at low temperatures by cooling the material to extremely low temperatures followed by controlled heating and tempering. Its function is to promote the transformation of retained austenite to martensite, precipitate ultrafine carbides, and effectively release internal stress, thereby enhancing the material's hardness, wear resistance, toughness, and fatigue resistance. Liquid nitrogen can be used as the cooling medium, or other cryogenic media such as helium or mixed refrigerants can be employed.

[0055] The purpose of immersing the target part in liquid nitrogen at -196℃ for 4 hours in the first cycle is to allow the target part to cool sufficiently at the extremely low temperature of liquid nitrogen, promoting the transformation of residual austenite in the material into martensite as much as possible, and creating conditions for subsequent carbide precipitation. The duration of immersion for 4 hours is designed to ensure that the internal temperature of the target part reaches -196℃ uniformly and to provide sufficient transformation time. Natural rewarming at an ambient temperature of 20±5℃ means allowing the target part to slowly return to room temperature without forced heating or cooling. This slow heating process helps to reduce thermal stress caused by excessive temperature gradients, thereby avoiding cracking or deformation of the target part. The ambient temperature is controlled at 20±5℃ to ensure the stability and repeatability of the rewarming process.

[0056] In the second cycle, the material is immersed in liquid nitrogen at -196℃ for 6 hours. Compared to the first cycle, the longer immersion time aims to further promote the transformation of retained austenite and allow for more complete precipitation of ultrafine carbides, thereby further optimizing the microstructure and properties of the material. The stepped temperature recovery, with three stages of -100℃, -50℃, and 0℃, and a holding time of 4 hours in each stage, is a more refined temperature control method. Holding at each temperature stage can homogenize the internal temperature of the target part and allow for stress release and microstructure adjustment at different temperatures. For example, the higher temperature stage can promote the tempering of martensite and further improve the toughness of the material. Holding at each stage for 4 hours aims to ensure that these processes are fully carried out.

[0057] In the third cycle, the material is immersed in liquid nitrogen at -196℃ for 8 hours, which is the longest cryogenic immersion time. This is designed to maximize the transformation of residual austenite and the precipitation of carbides, bringing the material to its optimal state. Then, it is held at a constant temperature of 120℃ for 8 hours. This step is a low-temperature tempering after cryogenic treatment, which aims to stabilize the martensitic structure, further release internal stress, and may promote the precipitation of certain carbides, thereby improving the toughness and dimensional stability of the material, while avoiding a significant decrease in hardness. Holding at a constant temperature for 8 hours ensures sufficient tempering effect. Then, a low-temperature tempering is performed at 200℃ for 2 hours. This step is a tempering treatment at a higher temperature, which aims to further optimize the comprehensive mechanical properties of the material, such as improving toughness, reducing brittleness, and further stabilizing the dimensions of the material.

[0058] By performing a refined three-cycle cryogenic treatment, combined with multi-stage controlled warming and tempering processes, the microstructure of the material can be significantly optimized, maximizing the transformation of residual austenite into martensite and promoting the uniform precipitation of ultrafine carbides. This not only effectively releases residual stress inside the target part and significantly improves the dimensional stability of the material at extremely low temperatures, but also significantly enhances the hardness, wear resistance, impact toughness, and fatigue resistance of the target part. Therefore, this processing technology can ensure that the testing device operates stably and with high precision in a liquid nitrogen environment at -196℃ for a long time, effectively avoiding testing errors and equipment failures caused by unstable material properties, thereby extending the service life of the equipment and ensuring the reliability of the test results.

[0059] Precision machining and surface treatment: The transmission worm gear 4, transmission shaft 3 and drive shaft 7 are subjected to composite deep cryogenic treatment and then precision grinding with diamond grinding wheels to control coaxiality ≤0.002mm and surface roughness Ra≤0.4μm; the bevel gear 8 is carburized and quenched, then subjected to deep cryogenic pretreatment at -80℃ for 2 hours, and then precision grinding is performed to control the meshing clearance 0.005~0.01mm; the thread pair is preset with a clearance compensation of 0.01~0.03mm through finite element simulation, and after precision machining on a thread grinding machine, a composite coating of molybdenum disulfide and polytetrafluoroethylene is sprayed, and then a composite deep cryogenic process is performed to control the thread helix angle ≤3°.

[0060] Assembly: After pre-cooling the outer ring of the turntable bearing to -80℃, perform cold assembly. After assembly, run-in test at a speed of 1° / s for 2 hours to ensure that the bearing friction torque meets the standard. Install the low temperature protection housing 9 of the drive motor 6, check the sealing status of the isolation chamber and the connection between the temperature sensor and the adjustment system to ensure proper assembly, and inject inert gas into the isolation chamber.

[0061] Pre-cooling the outer ring of the turntable bearing to -80℃ before cold assembly utilizes the principle of thermal expansion and contraction of materials to achieve a tight fit between the bearing and mating parts, reducing assembly stress and ensuring stable bearing operation at low temperatures. The post-assembly running-in test, running at a specific speed for a period of time, verifies whether the bearing's frictional torque meets the standard and eliminates potential problems during the initial break-in period. After installing the cryogenic protection housing 9 of the drive motor 6, the sealing condition of the isolation chamber is checked, and inert gas is injected into it. This effectively prevents external moisture from entering the isolation chamber and condensing into ice at low temperatures, while also reducing heat transfer and protecting the drive motor 6 for normal operation in a liquid nitrogen environment.

[0062] Debugging: Under normal temperature conditions, the positioning accuracy and repeatability of the bearing turntable 1 are calibrated using a laser interferometer; then liquid nitrogen is injected into the liquid nitrogen tank 11 and pre-cooled at a preset cooling rate of 5℃ / min. After the turntable surface temperature reaches -196℃ and stabilizes for 10 minutes, the transmission smoothness, self-locking performance and the operating status of the protection structure of the drive motor 6 are tested.

[0063] The debugging process includes the following specific steps: Room temperature calibration: The positioning accuracy and repeatability are tested at 10° intervals from 0° to 360° using a laser interferometer. The positioning accuracy and repeatability are tested three times for each angle, and the average value is taken as the reference data. Room temperature calibration refers to the precise measurement and recording of key motion parameters of the testing device when the equipment is at room temperature. By performing multi-point tests at 10° intervals throughout the entire rotation range from 0° to 360°, the positioning accuracy and repeatability of the bearing turntable 1 can be comprehensively evaluated.

[0064] Low temperature stability verification: The test turntable was cooled to -196℃ and remained stable for a preset time. The room temperature calibration steps were repeated, and the difference in accuracy data between low temperature and room temperature was compared. Low-temperature stability verification aims to evaluate the performance of the test device at liquid nitrogen operating temperatures. The test turntable is cooled to -196°C and maintained at this temperature for a period of time to ensure that the entire system reaches thermal equilibrium. Under these stable low-temperature conditions, the measurement steps of room-temperature calibration are repeated, i.e., the positioning accuracy and repeatability are tested using a laser interferometer, which can directly reflect the accuracy changes of the device at actual operating temperatures.

[0065] Thermal cycling verification: Multiple stages of thermal cycling were completed, with the number of cycles gradually increasing in each stage. In this embodiment, the number of cycles in each stage was 50, 100, 200, 300, 400, and 500. Of course, the number of cycles in each stage can also be determined according to the actual test conditions. After each stage, the device was kept at -196℃ for 2 hours and then placed at room temperature for 2 hours. The accuracy was then retested, and the accuracy decay was recorded to analyze the long-term stability. After completing 500 thermal cycles, the actual positioning accuracy of the device was ±0.008°, the repeatability was ±0.004°, the bearings showed no obvious wear, and the accuracy decay was not significant. The transmission and support components were not optimized for low-temperature environments. At low temperatures, materials become brittle, meshing clearances change significantly, threaded pairs are prone to jamming, bearings wear severely, and the equipment's service life is short, typically ≤50 thermal cycles. Thermal cycling verification simulates the temperature fluctuations the device might experience in actual use, evaluating its durability and stability under repeated temperature changes. This verification simulates fatigue effects during long-term service by designing multiple stages of thermal cycling and gradually increasing the number of cycles in each stage. After each cycle stage, the device is held at -196°C for 2 hours, followed by 2 hours at room temperature to ensure the materials fully experience temperature stress. Afterwards, accuracy is retested to detect the cumulative impact of thermal cycling on the device's positioning accuracy and repeatability. This helps identify potential problems caused by material thermal expansion and contraction, stress release, or changes in component fit.

[0066] The testing of transmission smoothness, self-locking performance, and the operating status of the drive motor protection structure includes the following steps: Continuous operation test: At -196℃, the bearing turntable 1 runs continuously for 8 hours at a speed of 1° / s and under load of 50kg, while monitoring the status, sealing performance and transmission of the drive motor 6. The continuous operation test aims to evaluate the reliability and stability of the test device under long-term operation in extreme low temperature environments. In a liquid nitrogen environment at -196℃, the bearing turntable 1 rotates at a speed of 1° / s and is subjected to a preset load for 8 hours. The test can expose the failure modes that may occur in the device during long-term low-temperature dynamic operation, such as overheating of the drive motor 6, seal failure, transmission jamming, or accelerated wear.

[0067] Load limit test: Under two environments, at room temperature and -196℃, multiple loads of different weights are applied to the test turntable, with the weight of the load gradually increasing. Loads of 20kg, 50kg, 80kg and 100kg can be applied respectively to test the positioning accuracy, self-locking performance and vibration, where the vibration must be less than or equal to 0.1g. Load limit testing is used to evaluate the performance of the testing device under different load conditions, including two extreme temperature environments: room temperature and -196°C. By applying multiple loads of different weights on the test turntable, the weight change of the test piece in actual testing can be simulated. In this process, the positioning accuracy of the testing device, the self-locking performance of the transmission mechanism, and the vibration of the entire system are required. This helps to determine the maximum load capacity of the device and its stability under heavy load, ensuring that it can provide accurate test results under various load conditions.

[0068] Sealing performance test: Liquid nitrogen is injected into the liquid nitrogen tank 11 to the preset level and monitored for 4 hours. The amount of liquid nitrogen leakage from the protective shell 9 and the water vapor content inside the equipment are recorded to ensure that the leakage is ≤0.5L / h and the water vapor content is ≤5% RH. In this embodiment, the liquid nitrogen leakage is 0.3L / h and the water vapor content inside the equipment is 3% RH. To verify the sealing integrity of the cryogenic protection device in a liquid nitrogen environment, liquid nitrogen is injected into the liquid nitrogen tank 11 to the preset level and continuously monitored for 4 hours. This can check for signs of liquid nitrogen leakage or external moisture intrusion into the isolation chamber. This is crucial for protecting non-cryogenic components such as the drive motor 6 from direct contact with liquid nitrogen and the effects of low temperature, ensuring their long-term reliable operation.

[0069] Performance testing of target parts: Low-temperature hardness test, low-temperature impact test, and dimensional stability test are performed sequentially on the testing device.

[0070] The physical properties of key materials and components constituting the testing apparatus are evaluated under cryogenic conditions. This includes cryogenic hardness testing, cryogenic impact testing, and dimensional stability testing, which verifies whether the selected materials and processing techniques meet the performance requirements under liquid nitrogen conditions, ensuring the structural integrity and functional reliability of the apparatus.

[0071] The specific test steps for the performance testing of the target part are as follows: Low-temperature hardness test: The Vickers hardness test is conducted at -196℃ to ensure that the hardness of the target part meets the standard. In this embodiment, the hardness needs to reach HRC58~62. Low-temperature impact test: The Charpy impact tester is used at -196℃ to ensure that the impact energy of the target part meets the standard. In this embodiment, the impact energy needs to be ≥20J / cm². Dimensional stability test: After the target part is kept at 196℃ for 24 hours, the dimensions of the target part are measured to ensure that the deformation of the target part meets the standard. The dimensions are compared with those at room temperature before the heat preservation to ensure that the deformation is ≤0.001mm.

[0072] By conducting low-temperature hardness testing at -196°C, the resistance to plastic deformation of the target part at liquid nitrogen operating temperatures can be quantified, ensuring that its surface does not fail prematurely under load. Simultaneously, low-temperature impact testing at -196°C can assess the target part's resistance to brittle fracture at extremely low temperatures, which is crucial for preventing sudden failure under impact or vibration conditions. Furthermore, by conducting dimensional stability testing on the target part after holding it at -196°C for 24 hours, the deformation of the target part after long-term low-temperature exposure can be precisely monitored, thereby verifying its stability in a liquid nitrogen environment. The system ensures precise geometric accuracy and assembly fit to avoid dimensional drift caused by thermal shrinkage or phase transformation. Performance testing of the material itself at extremely low temperatures complements the previous debugging steps for the overall function and structural integrity of the device, forming a more comprehensive and rigorous quality control system. This approach not only verifies the macroscopic operating status of the device but also deeply safeguards the long-term reliability and stability of the target components in a liquid nitrogen environment from a material perspective. This effectively solves the problem of material low-temperature performance defects that cannot be fully exposed through functional testing alone, ensuring the high precision and long lifespan of the testing device under extreme conditions.

[0073] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A testing device for use in a liquid nitrogen environment, characterized in that, include: Liquid nitrogen tank, the liquid nitrogen tank being used to provide a liquid nitrogen environment; A test turntable, which is set inside a liquid nitrogen bath, is used to place the test piece; A drive mechanism, the drive mechanism including a drive motor, the drive motor being used to drive the test turntable to rotate; A low-temperature protection device includes a protective housing and a sealing connecting sleeve disposed within the protective housing. An isolation cavity is formed between the protective housing and the sealing connecting sleeve. The sealing connecting sleeve is used to install the drive end of a drive motor to enclose and protect the drive end of the drive motor.

2. The testing device for use in a liquid nitrogen environment as described in claim 1, characterized in that, It also includes a temperature adaptive adjustment mechanism disposed within the protective housing. The temperature adaptive adjustment mechanism includes multiple temperature sensors and a heating device. The multiple temperature sensors are respectively disposed within the isolation cavity, on the drive motor housing, and on the drive motor windings. The heating device is disposed on the protective housing and is electrically connected to the temperature sensors on the drive motor housing to adjust the temperature of the drive motor.

3. The testing device for use in a liquid nitrogen environment as described in claim 2, characterized in that, The protective housing is also provided with an air inlet pipe and an exhaust pipe. The air inlet pipe is used to connect with an external inert gas supply device to inject inert gas into the isolation chamber, and the exhaust pipe is used to discharge the inert gas in the isolation chamber.

4. The testing device for use in a liquid nitrogen environment as described in claim 3, characterized in that, The inner wall of the protective shell is provided with a heat insulation layer, and the outer wall of the protective shell is provided with a heat insulation layer.

5. The testing device for use in a liquid nitrogen environment as described in claim 1, characterized in that, It also includes a transmission mechanism, which includes a mounting frame and a transmission shaft mounted on the mounting frame. The transmission shaft is used to drive the test turntable to rotate. The drive mechanism also includes a support frame and a drive shaft that is driven by the drive end of the drive motor. The drive motor and the drive shaft are mounted on the support frame. The transmission shaft and the drive shaft are provided with meshing bevel gears.

6. The testing device for use in a liquid nitrogen environment as described in claim 5, characterized in that, The test turntable includes a bearing turntable and a support platform disposed on the bearing turntable. The support platform is used to place the test piece. The transmission mechanism also includes a transmission worm gear disposed on the mounting frame. The transmission worm gear is connected to the transmission shaft and is in transmission cooperation with the bearing turntable to drive the bearing turntable to rotate.

7. A testing method for use in a liquid nitrogen environment, characterized in that, A testing apparatus for use in a liquid nitrogen environment according to any one of claims 1-6 includes the following steps: Fix the test piece on the support platform, connect the testing device to the external control system, and inject liquid nitrogen into the liquid nitrogen tank to the preset level; The external control system is activated, and pre-cooling is performed according to the preset cooling rate. The temperature adaptive adjustment mechanism keeps the drive motor temperature between -50℃ and 10℃. The temperature of the turntable surface to be tested reaches -196℃ and remains stable within the preset time, ready to start the test. The rotation angle and speed of the test turntable are controlled by an external control system. After the test is completed, the temperature is increased at the preset heating rate. After the temperature of the test turntable returns to room temperature, the power is turned off, the test piece is removed, and the residual liquid nitrogen and surface impurities in the liquid nitrogen tank are cleaned.

8. A processing technology for a testing device in a liquid nitrogen environment, characterized in that, The method for processing a testing device for a liquid nitrogen environment as described in any one of claims 1-6 includes the following steps: The target parts are forged and rough machined sequentially to near the finished size, and then carburized and quenched or tempered according to the purpose of the target parts. The target parts include bearing turntable, bearing table, transmission shaft, drive shaft, transmission worm gear and bevel gear. The target part is subjected to three cycles of deep cryogenic treatment according to the preset process parameters. After each deep cryogenic cycle, the key dimensions of the target part are sampled and inspected to ensure that the deformation meets the design requirements. The transmission worm and transmission shaft are precision ground with diamond grinding wheels to control coaxiality and surface roughness; the bevel gears are precision ground to control meshing clearance; and the threaded pairs are sprayed with a composite coating to improve low-temperature lubrication performance. After pre-cooling the outer ring of the turntable bearing to -80℃, cold assembly is performed. After assembly, a 2-hour running-in test is conducted at a speed of 1° / s to ensure that the bearing friction torque meets the standard. The low-temperature protection housing of the drive motor is installed, and the sealing status of the isolation chamber and the connection between the temperature sensor and the adjustment system are checked to ensure proper assembly. Inert gas is then injected into the isolation chamber. Under normal temperature conditions, the positioning accuracy and repeatability of the bearing turntable are calibrated. Then, liquid nitrogen is injected into the liquid nitrogen bath and pre-cooled at a preset cooling rate. Once the turntable surface temperature reaches -196℃ and remains stable within a preset time, the transmission smoothness, self-locking performance, and the operating status of the drive motor protection structure are tested.

9. The processing technology for a testing device in a liquid nitrogen environment as described in claim 8, characterized in that, The process of performing three cycles of deep cryogenic treatment on the target part according to preset process parameters includes the following steps: The target part was immersed in liquid nitrogen at -196℃ for 4 hours and then allowed to recover naturally at an ambient temperature of 20±5℃. Then the target part was immersed in liquid nitrogen at -196℃ for 6 hours, and then gradually warmed up in three stages: -100℃, -50℃ and 0℃, with each stage held for 4 hours. The target part is then immersed in liquid nitrogen at -196°C for 8 hours, kept at a constant temperature of 120°C for 8 hours, and then subjected to low-temperature tempering at 200°C for 2 hours.

10. The processing technology for a testing device in a liquid nitrogen environment as described in claim 8, characterized in that, The calibration of the bearing turntable positioning accuracy and repeatability includes the following steps: The positioning accuracy and repeatability were tested using a laser interferometer at 10° intervals from 0° to 360°, and the baseline data were recorded. The test turntable was cooled to -196℃ and remained stable for a preset time. The room temperature calibration procedure was then repeated. Multiple stages of hot and cold cycling were completed, with the number of cycles gradually increasing in each stage. After each stage, the temperature was kept at -196℃ for 2 hours and then placed at room temperature for 2 hours before accuracy retesting was performed. The test of transmission smoothness, self-locking performance, and the operating status of the drive motor protection structure includes the following steps: At -196℃, the bearing turntable was continuously operated at a speed of 1° / s and under load for 8 hours to monitor the status of the drive motor, sealing performance and transmission. At both room temperature and -196℃, multiple loads of different weights were applied to the test turntable to test positioning accuracy, self-locking performance, and vibration. Liquid nitrogen was injected into the liquid nitrogen tank to the preset level, and the sealing performance of the protective shell was continuously monitored for 4 hours. The target part was subjected to low-temperature hardness test, low-temperature impact test, and dimensional stability test in sequence.

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