Apparatus and method for measuring amount of displacement of thermal expansion of metal member

Abstract

An apparatus for measuring the amount of displacement of thermal expansion of a metal member. The apparatus comprises: a displacement calculation module (6); a first displacement sensor (2), which comprises a first iron core (22) and a first coil (21) sleeved outside the first iron core (22), wherein the first iron core (22) is suitable for being connected to an object (7) to be measured; a first signal processor (4), one end of which is electrically connected to the first coil (21); a second displacement sensor (3), which has the same model and specifications as the first displacement sensor (2), wherein the second displacement sensor (3) comprises a second iron core (32) and a second coil (31) sleeved outside the second iron core (32), and the second displacement sensor (3) is suitable for being spaced apart from said object (7); a second signal processor (5), one end of which is electrically connected to the second coil (31). The displacement calculation module (6) receives a first amount of displacement measured by the first signal processor (4) and a second amount of displacement measured by the second signal processor (5), and calculates the difference between the first amount of displacement and the second amount of displacement, so as to obtain the amount of displacement of thermal expansion of said object (7). An error caused by thermal deformation of a first displacement sensor (2) itself can be corrected, thereby improving the measurement precision. Further disclosed is a method for measuring the amount of displacement of thermal expansion of a metal member.

Description

A device and method for measuring the displacement of thermal expansion of metal parts

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 28, 2023, with application number 202311091936.5 and invention name “A device and method for measuring the displacement of thermal expansion of metal parts”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of thermal expansion displacement measurement, and in particular to a device and method for measuring the displacement of thermal expansion of a metal part. Background Art

[0003] The temperature difference between the containers or pipelines in power plants during cold and normal hot operation ranges from several hundred degrees Celsius. Large containers and pipelines in particular will not only deform and displace due to the temperature rise during operation, but also further deform and displace due to the pressure of the internal medium.

[0004] To ensure the reliability of power plant vessels and piping, it's necessary to determine whether the direction and magnitude of thermal expansion are within design parameters, allowing for a complete assessment of the equipment's safety status. Consequently, the accuracy of thermal expansion measurements significantly impacts the safe operation of the equipment.

[0005] Two Chinese patent documents, CN202310205501.2 and CN202310205498.4, respectively disclose a device for measuring the displacement of equipment using a displacement sensor. However, for containers or pipelines in a power plant operating in a normal hot state, the displacement sensor itself undergoes significant thermal deformation due to the high temperature at which it is exposed. Measuring the displacement of the power plant container or pipeline due to thermal expansion using a significantly deformed displacement sensor will result in a superposition of the thermal deformation of the displacement sensor itself and the thermal expansion of the object being measured, thus reducing the accuracy of the measurement.

[0006] In view of the above-mentioned deficiencies, it is necessary to design a device and method for measuring the displacement of thermal expansion of metal parts.

[0007] Summary of the Invention

[0008] Therefore, the technical problem to be solved by this application is that measuring the displacement of thermal expansion of containers or pipelines in power plants by using displacement sensors after large thermal deformation will reduce the accuracy of the measurement results, and thus a device and method for measuring the displacement of thermal expansion of metal parts are provided.

[0009] To solve the above technical problems, the technical solutions of this application are as follows:

[0010] A device for measuring the displacement of thermal expansion of a metal part, the device comprising:

[0011] Displacement calculation module;

[0012] The first displacement sensor includes a first iron core and a first coil sleeved outside the first iron core, wherein the first iron core is suitable for connecting with the object to be measured;

[0013] a first signal processor, one end of which is electrically connected to the first coil, and the other end of which is electrically connected to the displacement calculation module;

[0014] a second displacement sensor having the same model and specifications as the first displacement sensor, the second displacement sensor comprising a second iron core and a second coil sleeved outside the second iron core, the second displacement sensor being adapted to be spaced apart from the object to be measured;

[0015] The second signal processor has one end electrically connected to the second coil and the other end electrically connected to the displacement calculation module; wherein,

[0016] The displacement calculation module receives a first displacement measured by the first signal processor and a second displacement measured by the second signal processor, and calculates a difference between the first displacement and the second displacement, where the difference is a displacement corresponding to thermal expansion of the object to be measured.

[0017] Optionally, the movement direction of the first iron core relative to the first coil is adapted to be parallel to the expansion direction of the point on the object to be measured that contacts the first iron core.

[0018] Optionally, the second displacement sensor and the first displacement sensor are arranged parallel to each other or perpendicular to each other.

[0019] Optionally, the distance between the end of the second iron core exposed from the second coil and the object to be measured does not exceed the maximum measuring range of the measuring device.

[0020] Optionally, the measuring device comprises a measuring state, in which the positions of the first coil, the second core and the second coil remain unchanged.

[0021] The technical solution of this application has the following advantages:

[0022] 1. The device for measuring the displacement of a metal part due to thermal expansion provided by the present application comprises: a displacement calculation module; a first displacement sensor comprising a first iron core and a first coil sleeved outside the first iron core, the first iron core being suitable for connecting to an object to be measured; a first signal processor, one end of which is electrically connected to the first coil and the other end of which is electrically connected to the displacement calculation module; a second displacement sensor having the same model and specifications as the first displacement sensor, the second displacement sensor comprising a second iron core and a second coil sleeved outside the second iron core, the second displacement sensor being suitable for setting a distance from the object to be measured; a second signal processor, one end of which is electrically connected to the second coil and the other end of which is electrically connected to the displacement calculation module; wherein the displacement calculation module receives the first displacement measured by the first signal processor and the second displacement measured by the second signal processor. The second displacement is obtained, and the difference between the first displacement and the second displacement is calculated. The difference is the displacement due to thermal expansion of the object to be measured. Since the first displacement sensor and the second displacement sensor have the same model and specifications, and the second displacement sensor is suitable for being set at a distance from the object to be measured, the first displacement sensor and the second displacement sensor are placed in the same environment. With the help of the second displacement sensor that is not in contact with the object to be measured, the displacement of the first displacement sensor itself due to thermal expansion caused by the temperature of the object to be measured can be indirectly measured. By comparing the difference between the first displacement and the second displacement by the displacement calculation module, a correction can be formed for the displacement of the thermal expansion of the object to be measured measured by the first displacement sensor, thereby improving the measurement accuracy of the thermal expansion displacement of the object to be measured obtained.

[0023] 2. In the device for measuring the displacement of thermal expansion of a metal part provided in the present application, the first displacement sensor and the second displacement sensor are parallel to each other. In this way, the movement direction of the second iron core relative to the second coil will also be parallel to the expansion direction of the object to be measured, thereby better reflecting the displacement of the first displacement sensor caused by the thermal expansion of the object to be measured due to the temperature of the object to be measured, so that the corrected measurement result is more accurate.

[0024] 3. In the device for measuring the displacement of a metal part caused by thermal expansion provided in the present application, the distance between the end of the second iron core through which the second coil is exposed and the object to be measured does not exceed the maximum measuring range of the measuring device. In this way, the second iron core can be brought as close as possible to the object to be measured, thereby enabling the second displacement sensor to better reflect the displacement of the first displacement sensor caused by the thermal expansion of the object to be measured due to the temperature, thereby further improving the accuracy of the measurement results.

[0025] A method for measuring the displacement of thermal expansion of a metal part comprises the following steps:

[0026] Installing the measuring device: connecting the first iron core to the object to be measured, electrically connecting one end of the first signal processor to the displacement calculation module and the other end to the first coil, and fixing the first coil; placing the second displacement sensor in the same environment as the first displacement sensor, setting a distance between the second displacement sensor and the object to be measured, the second displacement sensor having the same model and specifications as the first displacement sensor, electrically connecting one end of the second signal processor to the displacement calculation module and the other end to the second coil, and fixing the second iron core and the second coil;

[0027] Measuring the displacement due to thermal expansion: When the object to be measured expands due to heat, the first signal processor measures a first displacement based on the movement of the first iron core relative to the first coil, and the second signal processor measures a second displacement based on the movement of the second iron core relative to the second coil. The displacement calculation module compares the difference between the first displacement and the second displacement, where the difference is the displacement due to thermal expansion of the object to be measured.

[0028] Optionally, before measuring the displacement caused by thermal expansion, a sensor zeroing step is also included: under normal temperature conditions, the first displacement sensor and the second displacement sensor need to be left standing for at least 0.4 hours before zeroing the first displacement sensor and the second displacement sensor.

[0029] Optionally, after the sensor is zeroed and before the displacement due to thermal expansion is measured, the method further includes heating and pressurizing steps: making the object to be measured have a target temperature and withstand a target pressure.

[0030] Optionally, it is necessary to wait for no less than 0.4 hours after reaching the target temperature and the target pressure before taking measurements again.

[0031] Optionally, it is used to measure the displacement due to thermal expansion of containers or pipelines in power plants.

[0032] 1. The method for measuring the displacement of a metal part due to thermal expansion provided by the present application comprises the following steps: installing a measuring device: connecting a first iron core to an object to be measured, electrically connecting one end of a first signal processor to a displacement calculation module and the other end to a first coil, and fixing the first coil; placing a second displacement sensor in the same environment as the first displacement sensor, setting a distance between the second displacement sensor and the object to be measured, the second displacement sensor having the same model and specifications as the first displacement sensor, electrically connecting one end of a second signal processor to a displacement calculation module and the other end to a second coil, and fixing the second iron core and the second coil; measuring the displacement of thermal expansion: the object to be measured is thermally expanded, and the first signal processor is connected to the displacement calculation module and the other end to the second coil, and fixing the second iron core and the second coil. A first displacement is measured based on the movement of the first iron core relative to the first coil, and a second signal processor measures a second displacement based on the movement of the second iron core relative to the second coil. A displacement calculation module compares the difference between the first and second displacements, where the difference represents the displacement of the object under test due to thermal expansion. In this way, the displacement of the first displacement sensor itself due to the temperature of the object under test can be indirectly measured with the help of a second displacement sensor that is not connected to the object under test. By comparing the difference between the first and second displacements by the displacement calculation module, a correction can be made to the displacement of the object under test due to thermal expansion measured by the first displacement sensor, thereby improving the accuracy of the measurement of the displacement of the object under test due to thermal expansion.

[0033] 2. The method for measuring the displacement of thermal expansion of metal parts provided in this application also includes a sensor zeroing step before measuring the displacement of thermal expansion: under normal temperature conditions, the first displacement sensor and the second position sensor need to be left to stand for at least 0.4 hours, and then the first displacement sensor and the second displacement sensor are zeroed. In this way, the first displacement sensor and the second displacement sensor can be subjected to the same environmental influence as the object to be measured during zeroing, further improving the accuracy of the measurement results.

[0034] 3. The method for measuring the displacement of thermal expansion of metal parts provided in this application requires waiting for no less than 0.4 hours after reaching the target temperature and target pressure before measuring. This allows the object to undergo sufficient thermal expansion and more sufficient external heat radiation from the object to be measured, so that the temperature of the environment in which the second displacement sensor is located is close to the temperature of the object to be measured. This allows the second displacement sensor to better reflect the displacement of the first displacement sensor caused by the thermal expansion of the object to be measured, further improving the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] FIG1 is a first structural schematic diagram of a device for measuring the displacement of thermal expansion of a metal part according to the present application;

[0037] FIG2 is a second structural schematic diagram of the device for measuring the displacement of thermal expansion of a metal part according to the present application;

[0038] FIG3 is a flow chart of a method for measuring the displacement of a metal part due to thermal expansion according to the present application.

[0039] Explanation of the accompanying drawings: 1. Fixed structure; 2. First displacement sensor; 21. First coil; 22. First iron core; 3. Second displacement sensor; 31. Second coil; 32. Second iron core; 4. First signal processor; 5. Second signal processor; 6. Displacement calculation module; 7. Object to be measured. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0041] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0043] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0044] As shown in Figures 1 to 3, this embodiment provides a device for measuring the displacement of thermal expansion of a metal part. The device includes a first displacement sensor 2, a second displacement sensor 3, a first signal processor 4, a second signal processor 5 and a displacement calculation module 6.

[0045] The first displacement sensor 2 includes a first iron core 22 and a first coil 21 sleeved outside the first iron core 22. The first iron core 22 is connected to the object to be measured 7 (the so-called connection can be that the first iron core 22 is only in contact with the object to be measured 7, or it can be connected to the object to be measured 7) so that the displacement of the thermal expansion of the object to be measured 7 can be measured by the first displacement sensor 2. For the convenience of subsequent description, the point where the first iron core 22 and the object to be measured 7 are connected is called the contact point. In this embodiment, the object to be measured 7 is a container or pipeline in a power plant, and the containers or pipelines in the power plant are usually faced with a high temperature and high pressure environment. Of course, the object to be measured 7 can also be other objects, which are not specifically limited here. In order to obtain better measurement results, optionally, the moving direction of the first iron core 22 relative to the first coil 21 is parallel to the expansion direction of the contact point on the object to be measured 7. When the surface of the object to be measured 7 at which the first iron core 22 contacts the surface is a plane, the length extension direction of the first iron core 22 is perpendicular to this plane. When the surface of the object to be measured 7 at which the first iron core 22 contacts the surface is a curved surface, the length extension direction of the first iron core 22 is perpendicular to the tangent plane on the object to be measured 7 passing through this contact point.

[0046] One end of the first signal processor 4 is electrically connected to the first coil 21 , and the other end is electrically connected to the displacement calculation module 6 .

[0047] The second displacement sensor 3 has the same specifications as the first displacement sensor 2. The second displacement sensor 3 includes a second core 32 and a second coil 31 disposed outside the second core 32. The second displacement sensor 3 is spaced apart from the object 7 to be measured, but does not contact the object 7. The spacing between the second core 32 and the object 7 does not exceed the maximum measuring range of the measuring device. This allows the second core 32 to be as close as possible to the object 7, allowing the second displacement sensor 3 to better reflect the displacement of the first displacement sensor 2 caused by thermal expansion due to the temperature of the object 7, further improving the accuracy of the measurement results.

[0048] One end of the second signal processor 5 is electrically connected to the second coil 31 , and the other end of the second signal processor 5 is electrically connected to the displacement calculation module 6 .

[0049] The displacement calculation module 6 receives the first displacement measured by the first signal processor 4 and the second displacement measured by the second signal processor 5, and calculates the difference between the first and second displacements to obtain the final displacement due to thermal expansion of the object 7. Specifically, the first signal processor 4 measures the first displacement based on the movement of the first iron core 22 relative to the first coil 21, and the second signal processor 5 measures the second displacement based on the movement of the second iron core 32 relative to the second coil 31. This is conventional technology and will not be further described here.

[0050] As shown in FIG1 , the first displacement sensor 2 and the second displacement sensor 3 are arranged parallel to each other. This allows the movement direction of the second core 32 relative to the second coil 31 to be parallel to the expansion direction of the contact point on the object 7. This allows the second displacement sensor 3 to better reflect the displacement of the first displacement sensor 2 caused by the temperature of the object 7. This allows the displacement calculation module 6 to calculate the difference between the first and second displacements, resulting in a more accurate final displacement of the object 7 after thermal expansion. Of course, as shown in FIG2 , the first displacement sensor 2 and the second displacement sensor 3 can also be arranged perpendicular to each other. Regardless of the configuration, the distance between the end of the second core 32 exposed from the second coil 31 and the object 7 does not exceed the maximum range of the measuring device. This allows the second core 32 to be as close to the object 7 as possible, allowing the second displacement sensor 3 to better reflect the displacement of the first displacement sensor 2 caused by the temperature of the object 7, further improving the accuracy of the measurement results.

[0051] The following describes a method for measuring the displacement of thermal expansion of a metal part using the device for measuring the displacement of thermal expansion of a metal part provided by this embodiment.

[0052] Install the measuring device: connect the first iron core 22 to the object to be measured 7, electrically connect one end of the first signal processor 4 to the first coil 21, and electrically connect the other end to the displacement calculation module 6, and fix the first coil 21. In this embodiment, the first coil 21 is fixed to the first position on the fixed structure 1; place the second displacement sensor 3 and the first displacement sensor 2 in the same environment, set the second displacement sensor 3 and the object to be measured 7 at a distance, and the second displacement sensor 3 has the same specifications and models as the first displacement sensor 2, electrically connect one end of the second signal processor 5 to the second coil 31, and electrically connect the other end to the displacement calculation module 6, and fix the second iron core 32 and the second coil 31. In this embodiment, as shown in Figure 1, The second coil 31 is fixed to a second position on the fixed structure 1, and the second iron core 32 is fixed to a third position on the fixed structure 1. From the perspective of FIG1 , the line connecting the third position and the second position is perpendicular to the line connecting the first position and the second position, so that the second displacement sensor 3 is arranged parallel to the first displacement sensor 2. Of course, as shown in FIG2 , the connection positions of the first coil 21, the second coil 31, the second iron core 32 and the fixed structure 1 can also be located on the same vertical line, so that the first displacement sensor 2 and the second displacement sensor 3 are arranged perpendicular to each other. Regardless of the arrangement, the fixed structure 1 needs to be made of a material with a small expansion coefficient to reduce the impact of thermal deformation of the fixed structure 1 on measurement accuracy. The fixed structure 1 can be a concrete wall or other temporary structure.

[0053] Sensor zeroing: Under normal temperature conditions, the first displacement sensor 2 and the second displacement sensor 3 need to be left to stand for at least 0.4 hours (optionally at least 0.5 hours) before zeroing them. This allows the first displacement sensor 2 and the second displacement sensor 3 to be subjected to the same environmental influences as the object 7 during zeroing, further improving the accuracy of the measurement results.

[0054] Temperature and pressure increase: making the object to be measured 7 reach the target temperature and withstand the target pressure;

[0055] Measuring the displacement due to thermal expansion: Wait for at least 0.4 hours (optionally at least 0.5 hours) before starting the measurement. This ensures that the object 7 to be measured undergoes sufficient thermal expansion. On the other hand, the object 7 to be measured can radiate heat to the outside more fully, so that the ambient temperature of the second displacement sensor 3 is approximately equal to the temperature of the object 7 to be measured. This enables the second displacement sensor 3 to better reflect the displacement of the first displacement sensor 2 caused by the thermal expansion of the object 7 under the influence of the temperature of the object 7 to be measured, thereby further improving the accuracy of the measurement results. Specifically, the first signal processor 4 measures the first displacement based on the movement of the first iron core 22 relative to the first coil 21, and the second signal processor 5 measures the second displacement based on the movement of the second iron core 32 relative to the second coil 31. The displacement calculation module 6 compares the difference between the first displacement and the second displacement, and the difference is the displacement due to the thermal expansion of the object 7 to be measured.

[0056] In this embodiment, since the first displacement sensor 2 and the second displacement sensor 3 have the same model and specifications, and the second displacement sensor 3 is spaced apart from the object to be measured 7, the first displacement sensor 2 and the second displacement sensor 3 are placed in the same environment. The second displacement sensor 3, which is not in contact with the object to be measured 7, can be used to indirectly measure the displacement of the first displacement sensor 2 itself due to the thermal expansion of the object to be measured 7 caused by the temperature. The displacement calculation module 6 compares the difference between the first displacement and the second displacement to obtain the final displacement of the thermal expansion of the object to be measured 7, thereby forming a correction for the displacement of the thermal expansion measured by the first displacement sensor 2, thereby making the final displacement of the thermal expansion of the object to be measured 7 more accurate.

[0057] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A device for measuring the displacement of thermal expansion of a metal part, characterized in that: The measuring device comprises: Displacement calculation module (6); A first displacement sensor (2) comprises a first iron core (22) and a first coil (21) sleeved outside the first iron core (22), wherein the first iron core (22) is suitable for connecting to an object to be measured (7); A first signal processor (4), one end of which is electrically connected to the first coil (21), and the other end of which is electrically connected to the displacement calculation module (6); a second displacement sensor (3) having the same model and specifications as the first displacement sensor (2), the second displacement sensor (3) comprising a second iron core (32) and a second coil (31) sleeved outside the second iron core (32), the second displacement sensor (3) being suitable for being arranged at a distance from the object to be measured (7); A second signal processor (5) has one end electrically connected to the second coil (31) and the other end electrically connected to the displacement calculation module (6); wherein: The displacement calculation module (6) receives the first displacement measured by the first signal processor (4) and the second displacement measured by the second signal processor (5), and calculates the difference between the first displacement and the second displacement, wherein the difference is the displacement due to thermal expansion of the object to be measured (7).

2. The device for measuring the displacement of thermal expansion of a metal part according to claim 1, characterized in that: The moving direction of the first iron core (22) relative to the first coil (21) is adapted to be parallel to the expansion direction of the point on the object to be measured (7) that is in contact with the first iron core (22).

3. The device for measuring the displacement of thermal expansion of a metal part according to claim 1, characterized in that: The second displacement sensor (3) and the first displacement sensor (2) are arranged parallel to each other or perpendicular to each other.

4. The device for measuring the displacement of thermal expansion of a metal part according to any one of claims 1 to 3, characterized in that: The distance between the end of the second iron core (32) exposed from the second coil (31) and the object to be measured (7) does not exceed the maximum measuring range of the measuring device.

5. The device for measuring the displacement of thermal expansion of a metal part according to any one of claims 1 to 3, characterized in that: The first coil (21), the second iron core (32) and the second coil (31) are suitable for being fixed on a fixed structure (1).

6. A method for measuring the displacement of thermal expansion of a metal part, characterized in that: The measuring method comprises the following steps: Installing the measuring device: connecting the first iron core (22) of the first displacement sensor (2) to the object to be measured (7), electrically connecting one end of the first signal processor (4) to the displacement calculation module (6), and electrically connecting the other end to the first coil (21) of the first displacement sensor (2), and fixing the first coil (21); placing the second displacement sensor (3) and the first displacement sensor (2) in the same environment, setting the second displacement sensor (3) and the object to be measured (7) at a distance, the second displacement sensor (3) and the first displacement sensor (2) having the same model and specification, electrically connecting one end of the second signal processor (5) to the displacement calculation module (6), and electrically connecting the other end to the second coil (31) of the second displacement sensor (3), and fixing the second iron core (32) and the second coil (31) of the second displacement sensor (3); Measuring the displacement due to thermal expansion: the object to be measured (7) expands due to heat, the first signal processor (4) measures a first displacement according to the movement of the first iron core (22) relative to the first coil (21), the second signal processor (5) measures a second displacement according to the movement of the second iron core (32) relative to the second coil (31), and the displacement calculation module (6) compares the difference between the first displacement and the second displacement, the difference being the displacement due to thermal expansion of the object to be measured (7).

7. The method for measuring the displacement of thermal expansion of a metal part according to claim 6, characterized in that: Before measuring the displacement amount of thermal expansion, a sensor zeroing step is also included: under normal temperature conditions, the first displacement sensor (2) and the second displacement sensor (3) need to be left to stand for no less than 0.4 hours, and then the first displacement sensor (2) and the second displacement sensor (3) are zeroed.

8. The method for measuring the displacement of thermal expansion of a metal part according to claim 7, characterized in that: After the sensor is zeroed and before the displacement due to thermal expansion is measured, the method further includes the steps of increasing temperature and pressure: making the object to be measured (7) have a target temperature and withstand a target pressure.

9. The method for measuring the displacement of thermal expansion of a metal part according to claim 8, characterized in that: After reaching the target temperature and the target pressure, it is necessary to wait for no less than 0.4 hours before measuring again.

10. The method for measuring the displacement of thermal expansion of a metal part according to any one of claims 6 to 9, characterized in that: Used to measure the displacement of thermal expansion of containers or pipelines in power plants.

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