Low-temperature thermal expansion coefficient testing device

Abstract

The utility model discloses a low-temperature thermal expansion coefficient testing device which comprises a base, a testing part and a connecting part, the base comprises a supporting frame arranged at the top of the base, a sliding frame is vertically arranged in the supporting frame in a sliding mode, a lifting frame is arranged at the top of the sliding frame, and the testing part is arranged on the side face of the lifting frame. The testing part comprises a displacement sensor arranged at the top of the lifting frame, the connecting part is arranged at the bottom of the lifting frame and comprises a connecting frame arranged at the bottom of the lifting frame, a rotating plate is rotationally arranged on the side face of the connecting frame, and a vacuum cover is vertically arranged at the bottom of the connecting frame in a sliding mode. According to the utility model, by arranging the testing part and the connecting part, when a thermal expansion coefficient test is carried out on a sample placed in the sample bracket, the vacuum cover is aligned with the connecting frame and is inserted from bottom to top in a sliding manner, and the rotating plate is rotated, so that the rotating plate is connected with the top of the clamping ring in a clamping manner; therefore, the vacuum cover can be quickly mounted at the bottom of the connecting frame.

Description

Technical Field

[0001] This utility model relates to the field of low-temperature thermal expansion coefficient testing technology, specifically to a low-temperature thermal expansion coefficient testing device. Background Technology

[0002] The demand for cryogenic materials in industry and scientific research is increasing, and the requirements for their performance data are becoming more comprehensive. Materials operating in cryogenic environments typically exhibit different physical properties compared to their room-temperature properties. Among these, the coefficient of thermal expansion (CTE) is a crucial performance indicator for materials or workpieces in engineering. Testing the CTE of materials at low temperatures is of great significance for the design of cryogenic equipment and devices, and is also essential for the safe use of cryogenic components. The phenomenon of an object's volume or length changing with temperature is called thermal expansion, and the degree of expansion is expressed by the CTE. Existing cryogenic CTE testing devices typically employ the push-rod method to test the CTE of solid samples. The sample within the testing device changes length with temperature, and the device records this change, thus obtaining the material's CTE in the cryogenic environment.

[0003] Existing low-temperature thermal expansion coefficient testing devices, when testing the thermal expansion coefficient of samples at low temperatures, also need to measure the thermal expansion coefficient of samples in a low-temperature vacuum environment in order to obtain more comprehensive data. This is usually done by covering the test head inside the low-temperature thermal expansion coefficient testing device with a vacuum cover. However, the existing connection method between the vacuum cover and the low-temperature thermal expansion coefficient testing device is usually to nest a retaining ring at the connection point. This method reduces the efficiency of vacuum cover installation and disassembly. Utility Model Content

[0004] The purpose of this invention is to provide a low-temperature thermal expansion coefficient testing device to solve the problem mentioned in the background art that existing low-temperature thermal expansion coefficient testing devices, when testing the thermal expansion coefficient of a sample in a low-temperature state, also need to measure the thermal expansion coefficient of the sample in a low-temperature vacuum environment in order to obtain more comprehensive data. Usually, a vacuum cover is placed on the outside of the test head inside the low-temperature thermal expansion coefficient testing device. However, the existing connection method between the vacuum cover and the low-temperature thermal expansion coefficient testing device is usually to nest a retaining ring at the connection, which reduces the efficiency of vacuum cover installation and disassembly.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a low-temperature thermal expansion coefficient testing device, comprising a base, a testing section, and a connecting section:

[0006] The base includes a support frame at the top, with a slide slidably mounted vertically inside the support frame. A lifting frame is mounted on top of the slide, and the slide slides along the support frame to drive the lifting frame to move up and down reciprocally. A test chamber is located at the top of the base to provide the temperature environment required for testing. The test section is located on the side of the lifting frame and includes a displacement sensor at the top of the lifting frame for measuring the expansion and contraction length of the sample. A sample holder is located at the bottom of the displacement sensor, and a placement slot for placing the sample is opened on the bottom side of the sample holder. A connecting part is located at the bottom of the lifting frame and includes a connecting bracket at the bottom of the lifting frame. A rotating plate is rotatably mounted on the side of the connecting bracket, and a vacuum hood is vertically slidably mounted at the bottom of the connecting bracket. The vacuum hood surrounds the sample holder, and the bottom of the rotating plate engages with the top of the vacuum hood. The rotating plate rotates to fix the position of the vacuum hood.

[0007] By adopting the above technical solution, when testing the coefficient of thermal expansion of a sample placed inside a sample holder, the vacuum shroud can be slid into the connecting frame from bottom to top by aligning it with the connecting frame, and the rotating plate can engage with the top of the retaining ring by rotating the rotating plate, thereby enabling the vacuum shroud to be quickly installed at the bottom of the connecting frame.

[0008] Preferably, the base further includes a groove formed inside the support frame, and the slide is embedded in the groove and vertically slidably connected to the support frame. By adopting the above technical solution, the slide can slide up and down along the groove. That is, the groove provides a clear sliding direction for the slide, ensuring that the slide can only slide vertically up and down along the groove inside the support frame. This guiding effect prevents the slide from shifting or wobbling during movement, thereby ensuring the stability of the entire device.

[0009] For example, when testing the low-temperature thermal expansion coefficient of a sample, the carriage needs to move precisely up and down to adjust the position of the sample in the test chamber. Without the guidance of the slide groove, the carriage may move irregularly, which will affect the accuracy of the test results.

[0010] Preferably, the base also includes a lead screw rotatably disposed inside the slide and a threaded groove formed inside the support frame. The lead screw is embedded in the threaded groove and threadedly connected to the support frame. A motor is installed at the top of the lifting frame, and the output end of the motor is connected to the top end of the lead screw. By adopting the above technical solution, the motor can drive the lead screw to rotate inside the slide, causing the rotating lead screw to move the slide up and down. Specifically, this design can accurately position the threaded connection between the lead screw and the threaded groove of the support frame. When the motor drives the lead screw to rotate, the lead screw will precisely drive the slide up and down according to the thread pitch, so as to facilitate precise control of the slide displacement.

[0011] Preferably, the testing unit also includes a push rod slidably embedded inside the sample holder. The top of the push rod is connected to a displacement sensor, and the bottom of the push rod abuts against the sample. By adopting the above technical solution, the deformation of the sample after being affected by low temperature can be collected by the displacement sensor. Specifically, the bottom of the push rod abuts against the sample, so that any deformation of the sample can be directly reflected in the displacement of the push rod. Since the top of the push rod is connected to the displacement sensor, the direct physical connection ensures a high degree of consistency between the sample deformation and the data collected by the displacement sensor, thereby achieving accurate measurement. In this way, even if the sample undergoes extremely small deformation in a low-temperature environment, it can be accurately transmitted to the displacement sensor for data collection through the push rod.

[0012] Preferably, the testing unit also includes a sliding sleeve that is slidably nested on the outside of the sample holder. The bottom of the sample holder has a ring of protruding bumps that abut against the bottom of the sliding sleeve. The periphery of the sliding sleeve has a hollowed-out structure. By adopting the above technical solution, the sliding sleeve can move up and down along the sample holder, protecting the sample inside the sample holder and preventing it from falling out due to deformation-induced shaking. This effectively prevents the sample from falling out. The sliding sleeve, nested on the outside of the sample holder, allows the sample to move up and down along the sample holder when it deforms and shakes due to thermal expansion or contraction in a low-temperature environment, thus constraining and limiting the sample. The protruding bumps at the bottom of the sample holder abut against the bottom of the sliding sleeve further enhance this constraint effect, ensuring that the sample remains inside the sample holder and does not fall out due to shaking, thereby protecting the integrity of the sample and avoiding the impact of sample damage on the test results. The hollowed-out structure of the sliding sleeve protects the sample without interfering with the displacement sensor's measurement. The displacement sensor mainly focuses on the change of the sample's length in the axial direction. The hollow design of the sliding sleeve ensures that it does not obstruct or affect the relative positional relationship between the displacement sensor and the sample, thus guaranteeing the accuracy of the measurement results.

[0013] Preferably, the connecting part further includes a connecting tube disposed at the bottom of the connecting frame, which is vertically slidably connected to the vacuum shroud. By adopting the above technical solution, the vacuum shroud can be aligned with the connecting frame and slid upwards, allowing the connecting frame to be inserted into the vacuum shroud.

[0014] The vacuum hood can be quickly and accurately installed by sliding it into the connecting bracket from bottom to top. This vertical sliding connection method makes the installation process simple and intuitive, requiring no complicated operating skills from the operator, allowing for easy installation of the vacuum hood and improving installation efficiency. This design also allows for a certain degree of dimensional deviation in the vertical sliding connection of the vacuum hood, enabling the connecting tube to be compatible with vacuum hoods of different sizes and specifications. As long as the inner diameter of the vacuum hood is slightly larger than the outer diameter of the connecting tube, it can be installed smoothly, improving the versatility of the device.

[0015] Preferably, the connecting part also has a rubber ring embedded around the connecting tube, which abuts against the inner wall of the vacuum chamber. By adopting the above technical solution, the friction between the rubber ring and the vacuum chamber can be improved.

[0016] Preferably, the connecting part also has rotating grooves on both sides of the connecting frame, and the rotating shafts on both sides of the rotating plate are embedded in the rotating grooves and rotatably connected to the connecting frame. By adopting the above technical solution, the rotating plate can rotate along the rotating groove to change its angle. This design changes the traditional complex installation method, improves installation efficiency, and reduces installation time. When it is necessary to disassemble the vacuum cover, simply rotate the rotating plate in the opposite direction to release the engagement connection with the retaining ring at the top of the vacuum cover, and then the vacuum cover can be easily slid down from the bottom of the connecting frame. The operation is simple and direct, facilitating quick disassembly.

[0017] Preferably, the connecting part also has a spring disposed on the side of the rotating plate near the connecting frame. The side of the connecting frame has a groove, and the spring is embedded in the groove. The spring is located between the connecting frame and the rotating plate. By adopting the above technical solution, the rotating plate can be rotated by the elastic force provided by the spring, and the spring can only extend and contract laterally due to the limitation of the groove, and cannot undergo longitudinal displacement.

[0018] The automatic reset function compresses or stretches the spring after the rotating plate rotates around the rotating groove. When no external force is applied, the spring force will push the rotating plate to automatically reset to the initial position or a specific set angle. This method is very convenient in operations that require frequent installation and removal of the vacuum cover, and can reduce the workload of operators manually adjusting the angle of the rotating plate.

[0019] Using this solution, the spring force ensures that the rotating plate and the retaining ring at the top of the vacuum chamber remain tightly engaged, preventing changes in the angle of the rotating plate due to slight vibrations or other external forces during testing. This ensures that the vacuum chamber is securely fixed and maintains the stability of the testing environment.

[0020] Preferably, the connecting part also has a retaining ring disposed on the top of the vacuum hood and an air extraction hole disposed on the side of the vacuum hood, and a retaining head disposed on the bottom of the rotating plate, which is engaged with the retaining ring.

[0021] By adopting the above technical solution, the vacuum shroud can be quickly fixed to the bottom of the connecting frame through the interlocking of the retaining ring and the retaining head.

[0022] Compared with the prior art, the beneficial effects of this utility model are: by providing a testing part and a connecting part, when testing the coefficient of thermal expansion of a sample placed inside the sample holder, the vacuum shroud can be slid into the connecting frame from bottom to top by aligning it with the connecting frame, and the rotating plate can be engaged with the top of the retaining ring by rotating the rotating plate, thereby enabling the vacuum shroud to be quickly installed at the bottom of the connecting frame. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of this application;

[0024] Figure 2 This is a schematic diagram of the overall testing section's rising structure in this application;

[0025] Figure 3 This is a schematic diagram of the overall cross-sectional structure of this application;

[0026] Figure 4 This is a schematic diagram of the testing department structure in this application;

[0027] Figure 5 This is a schematic diagram of the cross-sectional structure of the connection between the testing section and the connecting section in this application;

[0028] Figure 6 This is a schematic diagram of the cross-sectional structure of the connection part in this application;

[0029] Figure 7 This is a schematic diagram of the vacuum chamber structure of this application;

[0030] Figure 8 This is a schematic diagram of the connection structure between the connecting frame and the rotating plate in this application.

[0031] In the diagram: 1. Base; 101. Support frame; 102. Threaded groove; 103. Slide groove; 104. Slide carriage; 105. Lead screw; 106. Motor; 107. Lifting frame; 108. Test chamber; 2. Test section; 201. Displacement sensor; 202. Sample holder; 203. Push rod; 204. Slide sleeve; 3. Connecting section; 301. Connecting frame; 302. Connecting pipe; 303. Rotating groove; 304. Rotating plate; 305. Clamp; 306. Spring; 307. Rubber ring; 308. Vacuum hood; 309. Snap ring; 310. Evacuation port. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] Example 1

[0034] Please see Figure 1 , Figure 2 and Figure 3 This embodiment provides a technical solution: a low-temperature thermal expansion coefficient testing device, including a base 1, a testing part 2, and a connecting part 3.

[0035] The base 1 includes a support frame 101 mounted on top of the base 1. A slide 104 is vertically slidably mounted inside the support frame 101. A lifting frame 107 is mounted on top of the slide 104. The slide 104 slides along the support frame 101 to drive the lifting frame 107 to move up and down reciprocally. A test chamber 108 is provided on top of the base 1 to provide the temperature environment required for testing. This is prior art and will not be described in detail later. The test unit 2 is located on the side of the lifting frame 107. A displacement sensor 201 is mounted on top of the lifting frame 107. The displacement sensor 201 is used to measure the expansion and contraction length of the sample. A sample holder 202 is provided at the bottom of the displacement sensor 201. A placement groove for placing the sample is opened on the bottom side of the sample holder 202. A push rod 203 is slidably arranged inside the sample holder 202. The top of the push rod 203 is connected to the displacement sensor 201, and the bottom of the push rod 203 abuts against the sample. This allows the displacement sensor 201 to collect data on the deformation of the sample after being affected by low temperature. This is existing technology and will not be described in detail below.

[0036] The displacement sensor 201 operates on the principle of a linear variable differential transformer (LVDT). An LVDT is a sensor commonly used to measure displacement. Based on the principle of electromagnetic induction, it consists of a main coil and two slave coils. When the main coil is energized, the central movable iron core moves up and down from its center position. The two slave coils detect the change in the center position of the main coil and generate a voltage output that is proportional to the displacement of the iron core. The displacement value generated after the push rod 203 changes displacement is received by the displacement sensor 201. The connecting part 3 is set at the bottom of the lifting frame 107. A connecting frame 301 is set at the bottom of the lifting frame 107. A rotating plate 304 is rotatably set on the side of the connecting frame 301. A vacuum cover 308 is vertically slidably set at the bottom of the connecting frame 301. The vacuum cover 308 wraps around the outside of the sample holder 202. The bottom of the rotating plate 304 is engaged with the top of the vacuum cover 308. The rotating plate 304 rotates to fix the position of the vacuum cover 308. When testing the coefficient of thermal expansion of the sample placed inside the sample holder 202, the vacuum cover 308 can be aligned with the connecting frame 301 and slid in from bottom to top. By rotating the rotating plate 304, the rotating plate 304 is engaged with the top of the retaining ring 309, so that the vacuum cover 308 can be quickly installed at the bottom of the connecting frame 301.

[0037] When measuring the coefficient of thermal expansion of a sample in a low-temperature vacuum environment, the vacuum shroud 308 is aligned with the connecting frame 301 and slid in from bottom to top. Then, by rotating the rotating plate 304, it engages with the top of the retaining ring 309 on the vacuum shroud 308, allowing the vacuum shroud 308 to be quickly installed onto the bottom of the connecting frame 301. This design overcomes the low installation efficiency of traditional nested retaining ring methods, significantly saving installation time. When the vacuum shroud 308 needs to be removed after testing, simply rotate the rotating plate 304 in the opposite direction to disengage from the retaining ring 309, and then slide the vacuum shroud 308 down from the bottom of the connecting frame 301. The operation is simple and direct, improving the maintenance and preparation efficiency for the next use of the entire device.

[0038] The sample holder 202 in the testing section 2 has a placement slot on its bottom side, which can stably place the sample. The displacement sensor 201 is installed on the top of the lifting frame 107 and connected to the sample holder 202 at the bottom. It can accurately measure the change in length of the sample due to thermal expansion or contraction in a low-temperature environment.

[0039] Example 2

[0040] Please see Figure 3 , Figure 4 and Figure 5 This embodiment provides a technical solution: a low-temperature thermal expansion coefficient testing device, including a base 1 and a testing section 2.

[0041] A slide groove 103 is provided inside the support frame 101. The slide 104 is embedded in the slide groove 103 and vertically slidably connected to the support frame 101, allowing the slide 104 to slide up and down along the slide groove 103. A lead screw 105 is rotatably installed inside the slide 104. A threaded groove 102 is provided inside the support frame 101. The lead screw 105 is embedded in the threaded groove 102 and threadedly connected to the support frame 101. A motor 106 is installed on the top of the lifting frame 107. The output end of the motor 106 is connected to the top end of the lead screw 105, allowing the motor 106 to drive the lifting frame 107. 6 drives the lead screw 105 to rotate inside the slide 104, causing the rotating lead screw 105 to move the slide 104 up and down. A sliding sleeve 204 is slidably nested on the outside of the sample holder 202. A ring of protruding protrusions is provided at the bottom of the sample holder 202, and the protrusions abut against the bottom of the sliding sleeve 204. The periphery of the sliding sleeve 204 has a hollow structure, which allows the sliding sleeve 204 to move up and down along the sample holder 202, protecting the sample located inside the sample holder 202 and preventing it from falling out of the sample holder 202 due to shaking caused by deformation.

[0042] The sliding sleeve 204 is slidably nested on the outside of the sample holder 202, and the bottom of the sample holder 202 has a protrusion that abuts against the bottom of the sliding sleeve 204. The periphery of the sliding sleeve 204 has a hollow structure. This design not only protects the sample from falling out of the sample holder 202 due to shaking when it deforms under the influence of low temperature, but also does not hinder the displacement sensor 201 from measuring the length of the sample's expansion and contraction, thereby improving the accuracy of the test data.

[0043] When the motor 106 drives the lead screw 105 to rotate, the slide 104 can move up and down along the support frame 101, thereby driving the lifting frame 107 to move up and down reciprocally. This structural design allows the entire device to easily adjust the position of the sample in the test chamber 108 to adapt to different testing requirements.

[0044] The connecting tube 302 at the bottom of the connecting frame 301 is vertically slidably connected to the vacuum cover 308, and a rubber ring 307 is embedded around the connecting tube 302 to abut against the inner wall of the vacuum cover 308, increasing friction and ensuring the stability of the vacuum cover 308 sliding on the connecting frame 301. The rotating grooves 303 on both sides of the connecting frame 301 cooperate with the rotating shaft of the rotating plate 304, allowing the rotating plate 304 to rotate smoothly and change angles. At the same time, the spring 306 on the side of the rotating plate 304 near the connecting frame 301 is embedded in the groove on the side of the connecting frame 301. While providing elastic force to push the rotating plate 304 to rotate, it is limited by the groove and can only extend and retract laterally, ensuring the stability of the structure and thus better realizing the fixing function of the vacuum cover 308.

[0045] Example 3

[0046] Please see Figure 6 , Figure 7 and Figure 8 This embodiment provides a technical solution: a low-temperature thermal expansion coefficient testing device, including a connecting part 3, a connecting frame 301, and a vacuum chamber 308.

[0047] A connecting pipe 302 is provided at the bottom of the connecting frame 301. The connecting pipe 302 is vertically slidably connected to the vacuum cover 308, allowing the vacuum cover 308 to slide upwards from bottom to top, so that the connecting frame 301 is inserted into the vacuum cover 308. A rubber ring 307 is nested around the connecting pipe 302, and the rubber ring 307 abuts against the inner wall of the vacuum cover 308, which can improve the friction between the rubber ring 307 and the vacuum cover 308. Rotating grooves 303 are provided on both sides of the connecting frame 301. The rotating shafts on both sides of the rotating plate 304 are embedded in the rotating grooves 303 and rotatably connected to the connecting frame 301, allowing the rotating plate 304 to rotate along the rotating grooves 303 and change its angle. A spring 306 is provided on the side of the rotating plate 304 near the connecting frame 301. The side of the frame 301 has a groove, and the spring 306 is embedded in the groove. The spring 306 is located between the connecting frame 301 and the rotating plate 304. The spring 306 can push the rotating plate 304 to rotate by the elastic force provided by the spring 306. The spring 306 is limited by the groove and can only extend and retract laterally, and cannot move longitudinally. A retaining ring 309 is provided on the top of the vacuum cover 308. An air extraction hole 310 is provided on the side of the vacuum cover 308. A retaining head 305 is provided on the bottom of the rotating plate 304. The retaining head 305 and the retaining ring 309 are connected by a snap-fit ​​connection. The vacuum cover 308 can be quickly fixed below the connecting frame 301 by the snap-fit ​​between the retaining ring 309 and the retaining head 305. The air extraction hole 310 needs to be connected to an external air pump to extract the gas inside the vacuum cover 308.

[0048] The evacuation port 310 is used to connect an external air pump to extract gas from inside the vacuum chamber 308 to create a low-temperature vacuum environment. The sliding connection between the connecting pipe 302 and the vacuum chamber 308, and the abutment of the rubber ring 307, ensure convenient installation and disassembly while helping to maintain the vacuum state inside the vacuum chamber 308 and ensure a good seal. The rotating plate 304 cooperates with the rotating groove 303 of the connecting bracket 301 and the rotating shaft to achieve stable rotation. The limiting spring 306 ensures its lateral extension and contraction, making the engagement of the clamp 305 and the clamp ring 309 secure, preventing displacement or shaking of the vacuum chamber 308 during testing, and ensuring accurate test results.

[0049] In use, first, power on the device. Then, place the sample to be tested into the placement slot on the bottom side of the sample holder 202. Next, slide the sliding sleeve 204 to cover the sample, protecting it from falling out of the sample holder 202 due to deformation. Then, slide the vacuum cover 308 upwards, aligning it with the connecting bracket 301, so that the connecting bracket 301 is inserted into the vacuum cover 308. At the same time, the upward-moving vacuum cover 308 will contact the clamp 305 and push the clamp 305 away. Then, the spring 306 will push the rotating plate 304 to rotate. 306 is limited by the groove and can only extend and retract laterally, but cannot move longitudinally. This allows the clamping head 305 to hold the clamping ring 309 in place. Through the mutual engagement of the clamping ring 309 and the clamping head 305, the vacuum shroud 308 is quickly fixed below the connecting frame 301. Then, the evacuation port 310 needs to be connected to an external air pump to extract the gas inside the vacuum shroud 308. Next, the motor 106 drives the lead screw 105 to rotate inside the slide 104, causing the rotating lead screw 105 to move the slide 104 up and down, allowing the bottom of the vacuum shroud 308 to extend into the test chamber 108, thus completing the test of the expansion coefficient change of the sample in a low-temperature vacuum state.

[0050] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-temperature thermal expansion coefficient testing device, characterized in that, include: The base includes a support frame disposed on the top of the base, a slide is vertically slidably disposed inside the support frame, a lifting frame is disposed on the top of the slide, the slide slides along the support frame to drive the lifting frame to move up and down reciprocally, and a test chamber is disposed on the top of the base to provide the temperature environment required for testing. The testing unit is located on the side of the lifting frame. The testing unit includes a displacement sensor located on the top of the lifting frame. The displacement sensor is used to measure the extension and retraction length of the sample. A sample holder is located at the bottom of the displacement sensor. A placement slot for placing the sample is opened on the bottom side of the sample holder. The connecting part is located at the bottom of the lifting frame. The connecting part includes a connecting frame located at the bottom of the lifting frame. A rotating plate is rotatably provided on the side of the connecting frame. A vacuum cover is vertically slidably provided at the bottom of the connecting frame. The vacuum cover covers the outside of the sample holder. The bottom of the rotating plate is engaged with the top of the vacuum cover. The rotating plate rotates to fix the position of the vacuum cover.

2. The low-temperature thermal expansion coefficient testing device according to claim 1, characterized in that: The base also includes a slide groove inside the support frame, and the slide is embedded in the slide groove and vertically slidably connected to the support frame.

3. The low-temperature thermal expansion coefficient testing device according to claim 1, characterized in that: The base also includes a lead screw rotatably disposed inside the slide and a threaded groove opened inside the support frame. The lead screw is embedded in the threaded groove and threadedly connected to the support frame. A motor is provided on the top of the lifting frame, and the output end of the motor is connected to the top of the lead screw.

4. The low-temperature thermal expansion coefficient testing device according to claim 1, characterized in that: The testing unit also has a push rod that is slidably embedded inside the sample holder. The top of the push rod is connected to a displacement sensor, and the bottom of the push rod abuts against the sample.

5. The low-temperature thermal expansion coefficient testing device according to claim 4, characterized in that: The testing unit also has a sliding sleeve that is slidably nested on the outside of the sample holder. The bottom of the sample holder is provided with a ring of protruding bumps that abut against the bottom of the sliding sleeve. The periphery of the sliding sleeve has a hollow structure.

6. The low-temperature thermal expansion coefficient testing device according to claim 1, characterized in that: The connecting part also has a connecting pipe located at the bottom of the connecting frame, which is vertically slidingly connected to the vacuum hood.

7. The low-temperature thermal expansion coefficient testing device according to claim 6, characterized in that: The connector also has a rubber ring embedded around the connecting tube, which abuts against the inner wall of the vacuum chamber.

8. The low-temperature thermal expansion coefficient testing device according to claim 1, characterized in that: The connecting part also has rotating grooves on both sides of the connecting frame, and the rotating shafts on both sides of the rotating plate are embedded in the rotating grooves and rotatably connected to the connecting frame.

9. The low-temperature thermal expansion coefficient testing device according to claim 1, characterized in that: The connecting part also has a spring disposed on the side of the rotating plate near the connecting frame. The side of the connecting frame has a groove, and the spring is embedded in the groove. The spring is located between the connecting frame and the rotating plate.

10. The low-temperature thermal expansion coefficient testing device according to any one of claims 1 to 9, characterized in that: The connecting part also has a retaining ring on the top of the vacuum hood and an air extraction hole on the side of the vacuum hood. The bottom of the rotating plate is provided with a retaining head, which is engaged with the retaining ring.

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