Downward-mounted dynamic material low-temperature mechanical testing device and testing method thereof

Abstract

The present invention discloses a low-temperature mechanical testing device for materials with a power source and a testing method thereof. The low-temperature mechanical testing device for materials with a power source includes a crossbeam, a bracket, an actuator, a sensor, a bellows, a liquid nitrogen dewar, a base, a support rod, a connecting rod, a heater, an upper locking device and a lower locking device. The bellows and the sealing connection between the bellows and the support rod are used to achieve effective sealing of the low-temperature liquid nitrogen dewar and barrier-free application of load. The pressure sensor and the actuator are heated by the heater to prevent the pressure sensor and the actuator from freezing due to long-term low-temperature testing, effectively ensuring the test accuracy and safety of the equipment. The upper and lower locking devices are used to clamp the test sample, which can prevent loosening problems during fatigue testing and ensure the long-term operation stability of the equipment. The working stability is good, which is conducive to carrying out large-tonnage low-temperature fatigue performance testing of materials, and the operation is simple and the test results are highly accurate.

Description

Technical Field

[0001] The invention relates to the technical field of low-temperature mechanical testing of materials, and in particular to a bottom-mounted powered low-temperature mechanical testing device for materials and a testing method thereof. Background Art

[0002] Cryogenic materials are mainly used in aerospace, applied superconductors, gas industry and some major scientific projects, which are related to national economy and people's livelihood, social progress and national security. Accurate and comprehensive data on the cryogenic mechanical properties of materials is an important basis for related engineering design and scientific research. Testing the cryogenic properties of materials is the most direct and reliable means to obtain the cryogenic mechanical properties of materials.

[0003] A Chinese invention with publication number “CN106996894A” and name “A material low-temperature mechanical properties testing device” discloses a material low-temperature mechanical properties testing device, including a universal material testing machine, a refrigerator, a gas storage tank, a sample chamber, a vacuum pump, a vacuum insulation barrel and a heat-proof radiation barrel arranged in the vacuum insulation barrel. The universal material testing machine includes a base and a support frame arranged on the base. The vacuum insulation barrel is arranged on the base. The support frame is provided with a mechanical support for rigidly connecting to the sample to be tested. The mechanical support is located in the closed sample chamber, and the mechanical support can move up and down; one end of the sample chamber is located in the heat-proof radiation barrel, the cold head of the refrigerator extends into the sealed heat-proof radiation barrel and is connected to the outer wall of the sample chamber, the gas storage tank is connected to the sample chamber through an air inlet pipe, one end of the vacuum pump is connected to the gas storage tank, and the other end is connected to the sample chamber.

[0004] Although it can reduce the temperature in the specimen chamber to meet the temperature requirements. However, its actuator and pressure sensor are located on the top beam, and the working stability is relatively poor. However, for large-tonnage fatigue testing machines, in order to meet the test load requirements and improve working stability, the actuator can only be designed below the fatigue testing machine, which also increases the design difficulty of the low-temperature testing device. Therefore, how to solve the sealing performance of the material cryogenic mechanical testing device of the bottom-mounted powered fatigue testing machine to prevent the leakage of cryogenic liquids such as liquid nitrogen, and how to protect the actuator from low-temperature freezing are key technical issues in the design of the bottom-mounted powered material cryogenic mechanical testing device. Summary of the invention

[0005] In view of the above-mentioned deficiencies, the object of the present invention is to provide a bottom-mounted powered material low-temperature mechanical testing device with an ingenious and reasonable structural design that can ensure the long-term stable operation of the equipment.

[0006] Another object of the present invention is to provide a testing method for a bottom-mounted dynamic material low-temperature mechanical testing device.

[0007] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0008] A down-type dynamic material cryogenic mechanical testing device, comprising a crossbeam, a bracket, an actuator, a sensor, a bellows, a liquid nitrogen dewar, a base, a support rod, a connecting rod, a heater, an upper material locking device and a lower material locking device. The actuator is arranged on the base, and the liquid nitrogen dewar is arranged above the actuator through the bracket. A through hole is provided at the bottom of the liquid nitrogen dewar, the lower end of the bellows is sealed and connected to the edge of the through hole, and the upper end extends into the liquid nitrogen dewar, the lower end of the support rod is connected to the actuator, and the upper end axially passes through the bellows and extends into the liquid nitrogen dewar, the support rod is provided with a sealing portion corresponding to the upper end opening position of the bellows that can close the upper end opening of the bellows, the lower material locking device is arranged at the upper end of the support rod, the sensor is arranged on the crossbeam, the upper end of the connecting rod is connected to the sensor, and the lower end is provided with the upper material locking device, and the heater is arranged on the connecting rod.

[0009] As an improvement of the present invention, the sealing part is a knife-edge flange, the lower flange of the knife-edge flange is connected to the upper end of the bellows and welded and sealed, the upper flange of the knife-edge flange is sleeved on the support rod and welded and sealed, the lower flange is connected to the upper flange and is sealed by bolts, and a sealing gasket is provided between the lower flange and the upper flange.

[0010] As an improvement of the present invention, the sealing gasket is a copper gasket, which can be squeezed and deformed to fully fill the gap between the lower flange and the upper flange to improve the sealing effect.

[0011] As an improvement of the present invention, the cavity wall of the liquid nitrogen Dewar has an interlayer space, and the vacuum degree of the interlayer space is 1×10 -4 The liquid nitrogen dewar is provided with a vacuum flange port connected to the interlayer space, and the interlayer space is evacuated to 1×10 -4 Pa can reduce heat leakage, keep the liquid nitrogen Dewar warm, and reduce the volatilization rate of cryogenic liquid.

[0012] As an improvement of the present invention, a liquid nitrogen discharge port is provided at the bottom of the liquid nitrogen dewar, which can realize the rapid installation of samples and the rapid discharge of liquid nitrogen during the test process, bringing convenience to the test.

[0013] As an improvement of the present invention, the heater is preferably located at an end of the connecting rod close to the sensor.

[0014] As an improvement of the present invention, the lower end of the support rod is connected to the actuator via a lower adapter, and a heater is provided on the lower adapter. The heater is used to heat and protect the pressure sensor and the actuator to prevent the pressure sensor and the actuator from freezing, thereby effectively ensuring the test accuracy and the safety of the equipment.

[0015] As an improvement of the present invention, the lower locking device includes a locking flange and a fixing flange. The fixing flange is sleeved on the support rod and locked by radial screws. The locking flange is fixed to the fixing flange by axial bolts. A lower threaded hole for connecting to a test sample is provided at the center of the locking flange.

[0016] As an improvement of the present invention, the locking device includes an upper adapter seat and a locking clamp, the lower end face of the connecting rod is provided with an installation cavity, the upper part of the upper adapter seat is assembled in the installation cavity, the locking clamp is locked on the upper adapter seat and pressed on the lower end face of the connecting rod, and the lower end face of the upper adapter seat is provided with an upper threaded hole for connecting to a test sample.

[0017] A method for testing low-temperature mechanical properties of a material using a bottom-mounted power system, comprising the following steps:

[0018] S1: Screw the lower end of the test sample into the lower threaded hole of the locking flange, screw the upper end of the test sample into the upper threaded hole of the upper adapter, and then lock it with the locking clamp. Fixing with the locking clamp can prevent loosening during fatigue testing;

[0019] S2: Adjust the height of the crossbeam so that the locking flange moves downward and approaches the fixed flange, and then lock the height of the crossbeam;

[0020] S3: Rotate the fixing flange and the locking flange to align and fit them together, then screw the fixing flange into the support rod with radial screws, and then tighten the fixing flange and the locking flange with bolts; evacuate the interlayer space through the vacuum flange port;

[0021] S4: Turn on the heater control device to heat the heater to the set protection temperature; use the heater to heat the pressure sensor and the actuator to prevent the pressure sensor and the actuator 3 from freezing due to long-term low-temperature testing;

[0022] S5: Add liquid nitrogen into the liquid nitrogen dewar through the liquid nitrogen connecting pipe to ensure that the liquid nitrogen level completely covers the test sample, and use a liquid level gauge to regularly add liquid nitrogen to ensure the stability of the test; use a bellows and a knife-edge flange to seal the connection between it and the support rod to achieve effective sealing of the low-temperature liquid nitrogen dewar and barrier-free load application;

[0023] S6: After the test sample is completely cooled, the actuator is turned on for loading. During the loading process, the sensor collects data and feeds it back to the data acquisition system in real time;

[0024] S7: After the test is completed, the data acquired by the data acquisition system is saved and processed;

[0025] S8: Open the liquid nitrogen discharge port of the liquid nitrogen dewar, and put the remaining liquid nitrogen into the commercial liquid nitrogen dewar for storage and reuse;

[0026] S9: Remove the locking bolts to separate the locking flange from the fixed flange, raise the crossbeam to the required height and lock it, then remove the test sample. The entire test process is completed. The operation is simple and the test results are highly accurate, which brings convenience to the low-temperature mechanical testing of materials.

[0027] The beneficial effects of the present invention are as follows: the structure design of the down-type dynamic material cryogenic mechanical testing device provided by the present invention is reasonable, and the bellows and the sealing connection between the bellows and the support rod are adopted to realize the effective sealing of the cryogenic liquid nitrogen dewar and the barrier-free application of load, so as to reduce the leakage of cryogenic liquid and save the test cost. The pressure sensor and the actuator are heated by a heater to prevent the freezing of the pressure sensor and the actuator caused by long-term low-temperature testing, and the test accuracy and safety of the equipment are effectively guaranteed. The upper and lower locking devices are adopted to clamp the test samples, which can prevent the loosening problem during the fatigue test process, ensure the long-term operation stability of the equipment, and have good working stability, which is conducive to carrying out large-tonnage low-temperature fatigue performance testing of materials. In addition, the overall structure is easy to realize, easy to operate, and the test results are highly accurate, which brings convenience to the material cryogenic mechanical testing work, effectively improves the test work efficiency, and is conducive to promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0029] Figure 2 It is a schematic diagram of the partial decomposition structure of the present invention. DETAILED DESCRIPTION

[0030] Example: See Figure 1 and Figure 2 The present invention provides a bottom-mounted dynamic material low-temperature mechanical testing device, which includes a crossbeam 1, a bracket 2, an actuator 3, a liquid nitrogen dewar 4, an upper material locking device 5, a lower material locking device 6, a sensor 7, a support rod 8, a bellows 9, a base 10, a connecting rod 11 and a heater 12.

[0031] The actuator 3 is disposed on the base 10 , two support rods 13 are symmetrically and vertically disposed on the base 10 , and the crossbeam 1 is fixedly disposed on the two support rods 13 .

[0032] The top of the bracket 2 is located above the base 10, and the bottom of the liquid nitrogen dewar 4 is fixed to the top of the bracket 2, so as to be arranged above the actuator 3. The bottom of the liquid nitrogen dewar 4 is provided with a through hole 41, and the lower end of the bellows 9 is sealed and connected to the edge of the through hole 41, and the upper end extends into the liquid nitrogen dewar 4. Preferably, in order to keep the liquid nitrogen dewar 4 warm and reduce the waste of cryogenic liquid, the cavity wall of the liquid nitrogen dewar 4 has an interlayer space 42, and the vacuum degree of the interlayer space 42 is 1×10 -4 The liquid nitrogen dewar 4 is provided with a vacuum flange 43 connected to the interlayer space 42. The interlayer space 42 is evacuated to 1×10 -4 Pa, can achieve the effect of reducing heat leakage, keeping the liquid nitrogen Dewar 4 warm, and reducing the volatilization rate of the cryogenic liquid. A liquid nitrogen discharge port 44 is provided at the bottom of the liquid nitrogen Dewar 4, which can realize the rapid installation of the test sample 17 and the rapid discharge of liquid nitrogen during the test, bringing convenience to the test.

[0033] The lower end of the support rod 8 is connected to the actuator 3. Specifically, the lower end of the support rod 8 is connected to the actuator 3 via a lower adapter 15.

[0034] Specifically, a screw portion is provided at the lower end of the support rod 8, and an assembly screw hole matched with the screw portion is provided on the lower adapter seat 15. The screw portion is screwed into the assembly screw hole, and a locking clamp 16 is sleeved on the screw portion. The locking clamp 16 presses against the upper surface of the lower adapter seat 15 to achieve the purpose of locking. In order to ensure the stable conduct of long-term tests, a heater 12 is provided on the lower adapter seat 15. The heater 12 is used to heat and protect the actuator 3 to prevent the actuator 3 from freezing, effectively ensuring the normal operation and safety of the equipment.

[0035] The upper end of the support rod 8 axially passes through the bellows 9 and extends into the liquid nitrogen dewar 4. The support rod 8 is provided with a sealing portion 14 that can close the upper end opening of the bellows 9 at the upper end opening position corresponding to the bellows 9. The sealing portion 14 is preferably a knife-edge flange. The lower flange 141 of the knife-edge flange is connected to the upper end of the bellows 9 and welded and sealed. The upper flange 142 of the knife-edge flange is sleeved on the support rod 8 and welded and sealed. The lower flange 141 is connected to the upper flange 142 and is sealed by bolts, and a sealing gasket 143 is provided between the lower flange 141 and the upper flange 142. The sealing gasket 143 is preferably a copper gasket, which can be squeezed and deformed to fully fill the gap between the lower flange 141 and the upper flange 142 to improve the sealing effect.

[0036] The lower locking device 6 is arranged at the upper end of the support rod 8. Specifically, the lower locking device 6 includes a locking flange 61 and a fixing flange 62. The fixing flange 62 is sleeved on the support rod 8 and locked by radial screws. The locking flange 61 is fixed to the fixing flange 62 by axial bolts. The center position of the locking flange 61 is provided with a lower threaded hole for connecting with the test sample 17.

[0037] The sensor 7 is arranged on the cross beam 1, the upper end of the connecting rod 11 is connected to the sensor 7, and the lower end is provided with the locking device 5. Specifically, the locking device 5 includes an upper adapter seat 51 and a locking clamp 52. The lower end surface of the connecting rod 11 is provided with a mounting cavity, and the upper part of the upper adapter seat 51 is assembled in the mounting cavity. The locking clamp 52 is locked on the upper adapter seat 51 and pressed on the lower end surface of the connecting rod 11. The lower end surface of the upper adapter seat 51 is provided with an upper threaded hole for connecting with the test sample 17.

[0038] The heater 12 is arranged on the connecting rod 11. The heater 12 is preferably located at one end of the connecting rod 11 close to the sensor 7, so as to achieve a better heating effect. The heater 12 is used to heat and protect the pressure sensor 7 to prevent the pressure sensor 7 from freezing, thereby effectively ensuring the test accuracy and stable and reliable operation of the equipment.

[0039] When working, the testing method of the bottom-mounted dynamic material low-temperature mechanical testing device of the present invention is as follows:

[0040] S1: Screw the lower end of the test sample 17 into the lower threaded hole of the locking flange 61, screw the upper end of the test sample 17 into the upper threaded hole of the upper adapter 51, and then lock it with the locking clamp 52. Fixing with the locking clamp 52 can prevent loosening during fatigue testing;

[0041] S2: Adjust the height of the crossbeam 1 so that the locking flange 61 moves downward and approaches the fixing flange 62, and then lock the height of the crossbeam 1;

[0042] S3: Rotate the fixing flange 62 to align with the locking flange 61 and fit them together, then screw the fixing flange 62 into the support rod 8 with radial screws, and then tighten the fixing flange 62 and the locking flange 61 with bolts; evacuate the interlayer space 42 to 1×10 -4 Pa;

[0043] S4: Turn on the heater control device to heat the heater 12 to the set protection temperature; use the heater 12 to heat the pressure sensor 7 and the actuator 3 to prevent the pressure sensor 7 and the actuator 3 from freezing due to long-term low-temperature testing;

[0044] S5: Add liquid nitrogen into the liquid nitrogen Dewar 4 through the liquid nitrogen connecting pipe to ensure that the liquid nitrogen level completely covers the test sample 17, and use a liquid level gauge to regularly add liquid nitrogen to ensure the stable progress of the test; use a bellows 9 and a knife-edge flange to seal the bellows 9 and the support rod 8 to achieve effective sealing of the low-temperature liquid nitrogen Dewar 4 and barrier-free load application;

[0045] S6: After the test sample 17 is completely cooled, the actuator 3 is turned on for loading. During the loading process, the sensor 7 collects data and feeds it back to the data acquisition system in real time;

[0046] S7: After the test is completed, the data acquired by the data acquisition system is saved and processed;

[0047] S8: Open the liquid nitrogen outlet 44 of the liquid nitrogen Dewar 4, and put the remaining liquid nitrogen into the commercial liquid nitrogen Dewar 4 for storage and reuse;

[0048] S9: Remove the locking bolts to separate the locking flange 61 from the fixing flange 62, raise the crossbeam 1 to the required height and lock it, then remove the test sample 17. The entire test process is completed. The operation is simple and the test results are highly accurate, which brings convenience to the low-temperature mechanical testing of materials.

[0049] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention. As described in the above embodiments of the present invention, other test devices and test methods obtained by using the same or similar structures are all within the protection scope of the present invention.

Claims

1. A down-type dynamic material low temperature mechanical testing device, comprising a crossbeam, an actuator and a sensor, characterized in that: It also includes a bracket, a bellows, a liquid nitrogen dewar, a base, a support rod, a connecting rod, a heater, an upper locking device and a lower locking device. The actuator is arranged on the base, and the liquid nitrogen dewar is arranged above the actuator through the bracket. A through hole is arranged at the bottom of the liquid nitrogen dewar. The lower end of the bellows is sealed and connected to the edge of the through hole, and the upper end extends into the liquid nitrogen dewar. The lower end of the support rod is connected to the actuator, and the upper end axially passes through the bellows and extends into the liquid nitrogen dewar. The support rod is provided with a sealing portion capable of closing the upper end opening of the bellows at a position corresponding to the upper end opening of the bellows. The lower locking device is arranged at the upper end of the support rod, and the sensor is arranged on the crossbeam. The upper end of the connecting rod is connected to the sensor, and the lower end is provided with the upper locking device. The heater is arranged on the connecting rod; The lower end of the support rod is connected to the actuator through a lower adapter; a heater is provided on the lower adapter; The lower locking device comprises a locking flange and a fixing flange, the fixing flange is sleeved on the support rod and locked by radial screws, the locking flange is fixed to the fixing flange by axial bolts, and a lower threaded hole for connecting with the test sample is provided at the center of the locking flange; The upper locking device comprises an upper transfer seat and a locking clamp, the lower end surface of the connecting rod is provided with a mounting cavity, the upper part of the upper transfer seat is assembled in the mounting cavity, the locking clamp is locked on the upper transfer seat and pressed on the lower end surface of the connecting rod, and the lower end surface of the upper transfer seat is provided with an upper threaded hole for connecting with the test sample; The sealing part is a knife-edge flange, the lower flange of which is connected to the upper end of the bellows and welded and sealed, the upper flange of which is sleeved on the support rod and welded and sealed, the lower flange is connected to the upper flange and is sealed by bolts, and a sealing gasket is provided between the lower flange and the upper flange.

2. The bottom-mounted dynamic material low-temperature mechanical testing device according to claim 1 is characterized in that: The sealing gasket is a copper gasket.

3. The bottom-mounted dynamic material low-temperature mechanical testing device according to claim 1 is characterized in that: The cavity wall of the liquid nitrogen Dewar has an interlayer space, and the vacuum degree of the interlayer space is 1×10 -4 Pa.

4. The bottom-mounted dynamic material low-temperature mechanical testing device according to claim 3 is characterized in that: The liquid nitrogen dewar is provided with a vacuum flange port which is connected with the interlayer space, and the bottom of the liquid nitrogen dewar is provided with a liquid nitrogen discharge port.

5. A testing method for the bottom-mounted dynamic material low-temperature mechanical testing device according to any one of claims 1 to 4, characterized in that: It includes the following steps: S1: Screw the lower end of the test sample into the lower threaded hole of the locking flange, screw the upper end of the test sample into the upper threaded hole of the upper adapter, and then lock it with the locking clamp. Fixing with the locking clamp can prevent loosening during fatigue testing; S2: Adjust the height of the crossbeam so that the locking flange moves downward and approaches the fixed flange, and then lock the height of the crossbeam; S3: Rotate the fixing flange and the locking flange to align and fit them together, then screw the fixing flange into the support rod with radial screws, and then tighten the fixing flange and the locking flange with bolts; evacuate the interlayer space through the vacuum flange port; S4: Turn on the heater control device to heat the heater to the set protection temperature; heat the pressure sensor and the actuator through the heater; S5: Add liquid nitrogen into the liquid nitrogen dewar through the liquid nitrogen connecting pipe to ensure that the liquid nitrogen level completely covers the test sample, and use a liquid level gauge to add liquid nitrogen regularly to ensure the stable progress of the test; S6: After the test sample is completely cooled, the actuator is turned on for loading. During the loading process, the sensor collects data and feeds it back to the data acquisition system in real time; S7: After the test is completed, the data acquired by the data acquisition system is saved and processed; S8: Open the liquid nitrogen discharge port of the liquid nitrogen dewar, and put the remaining liquid nitrogen into the commercial liquid nitrogen dewar for storage and reuse; S9: Remove the locking bolts to separate the locking flange from the fixed flange, raise the beam to the required height and lock it, and then remove the test sample.

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